HHE Report No. HETA 96-0264-2713, Hagerman Fossil Beds ......Hagerman (elev. 2960 ft), on the east...

HETA 96-0264-2713Hagerman Fossil Beds National Monument,

National Park Service, U.S. Department of the InteriorHagerman, Idaho

Timothy E. Jiggens, MSPH, IHITJohn J. Cardarelli, MS

Steven H. Ahrenholz, Ph.D., CIH

This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not be universally applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved. Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reports



This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not be universally applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved.


applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved. Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reports

http://www.cdc.gov/niosh/hhe/reports



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PREFACEThe Hazard Evaluations and Technical Assistance Branch of NIOSH conducts field investigations of possiblehealth hazards in the workplace. These investigations are conducted under the authority of Section 20(a)(6)of the Occupational Safety and Health Act of 1970, 29 U.S.C. 669(a)(6) which authorizes the Secretary ofHealth and Human Services, following a written request from any employer or authorized representative ofemployees, to determine whether any substance normally found in the place of employment has potentiallytoxic effects in such concentrations as used or found.

The Hazard Evaluations and Technical Assistance Branch also provides, upon request, technical andconsultative assistance to Federal, State, and local agencies; labor; industry; and other groups or individualsto control occupational health hazards and to prevent related trauma and disease. Mention of company namesor products does not constitute endorsement by the National Institute for Occupational Safety and Health.

ACKNOWLEDGMENTS AND AVAILABILITY OF REPORTThis report was prepared by Timothy E. Jiggens, MSPH, IHIT, of the Health Related Energy ResearchBranch, Division of Surveillance, Hazard Evaluations and Field Studies (DSHEFS). Field assistance wasprovided by Greg McDonald, Ph.D., National Park Service. Analytical support was provided by ArdithGrote, NIOSH, and by Jim L. Gale, Stephen R. Black, and Peter M Kligmann, Data Chem Laboratories.Desktop publishing was performed by Pat Lovell. Review and preparation for printing was performed byPenny Arthur.

Copies of this report have been sent to employee and management representatives at HAFO and the OSHARegional Office. This report is not copyrighted and may be freely reproduced. Single copies of this reportwill be available for a period of three years from the date of this report. To expedite your request, includea self-addressed mailing label along with your written request to:

NIOSH Publications Office4676 Columbia ParkwayCincinnati, Ohio 45226

800-356-4674

After this time, copies may be purchased from the National Technical Information Service (NTIS) at5825 Port Royal Road, Springfield, Virginia 22161. Information regarding the NTIS stock number may beobtained from the NIOSH Publications Office at the Cincinnati address.

For the purpose of informing affected employees, copies of this report shall beposted by the employer in a prominent place accessible to the employees for aperiod of 30 calendar days.

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Health Hazard Evaluation Report 96-0264-2713Hagerman Fossil Beds National Monument,

National Park Service, U.S. Department of the InteriorHagerman, IdahoSeptember 1998

Timothy E. Jiggens, MSPH, IHITJohn J. Cardarelli, MS

Steven H. Ahrenholz, Ph.D., CIH

SUMMARYHagerman Fossil Beds National Monument (HAFO) is a unit of the National Park Service. The primary activitiesat HAFO are the excavation, preparation, display, and storage of fossilized mammal skeletons from the PliocineEpoch. On August 29, 1996, HAFO sent a letter to the National Institute for Occupational Safety and Health(NIOSH) requesting technical assistance because “fossil materials that we work with on a reoccurring basis havepotential for radon gas and gamma radiation exposure.”1 NIOSH made two site visits in response to this request.

The first visit took place May 14-15, 1997, immediately prior to the start of the dig season. NIOSH investigatedactivities in the Administration Building and Visitor Center, where sampling was conducted for total airborneparticulate, external ionizing radiation exposure, and surface radiation contamination. Active and passive radonmonitors were installed in the two buildings, and employees were provided radiation monitoringthermoluminescent detectors (ring badges and whole body badges). Soil and fossil samples were taken from thedig site (known as the Horse Quarry) and analyzed for gamma emitting radioisotopes. The soil samples were alsoanalyzed for silica content.

The second visit occurred July 23-24, 1997, at the peak of the dig season. NIOSH investigated outdoor workactivities at the monument, particularly at the Horse Quarry. Employees were monitored for respirable airbornesilica, respirable airborne particulate, total airborne particulate, and heat stress. Performance of the local exhaustventilation in the fossil preparation laboratory was also assessed.

Sample results indicate that the soil at HAFO is not abnormally radioactive. With a specific activity of 700 ± 200picoCuries/gram (pCi/g), the fossils at HAFO are several hundred times more radioactive than the soil, but stillexhibit less than one percent of the radioactivity of some uranium bearing minerals. Exposures to externalradiation at HAFO were found to be low, and no radioactive contamination of indoor surfaces was found.

The fossils at HAFO are sources of radon gas. Radon concentrations of about 8 picoCuries/liter of air (pCi/L) werefound in the collections room, a poorly ventilated room where fossils are stored. Radon levels ranged from 128to 500 pCi/L inside the collections cabinets. Radon concentrations in other parts of the Administration Buildingand Visitor Center were less than 2.5 pCi/L. The Environmental Protection Agency (EPA) recommends thatcorrective measures be taken when radon levels inside residences exceed 4 pCi/L.20

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Some outdoor workers at HAFO may be overexposed to heat during typical summer afternoons. A formal heatstress management program is needed at HAFO due to the remote location, potential for heat overexposure, andpresence of individuals not acclimated to hot conditions.

The soil at HAFO contains 20-25% silica by mass, but exposures to respirable airborne silica were low. Only one(0.04 milligrams respirable silica per cubic meter of air [mg/m3]) of ten samples was high enough to quantify.Exposures to respirable airborne particulate (10 samples, all less than 0.22 mg/m3) and total airborne particulate(13 valid results, all less than 0.68 mg/m3) were also low.

The ventilation hoods in the fossil preparation lab serve to physically contain dust and projectiles generated duringfossil processing. However, the hoods generate insufficient flow to remove the dust and lack air cleaners to removedust from the exhausted air.

Results of this NIOSH Health Hazard Evaluation (HHE) demonstrate that potential health hazards existat HAFO. Employees who work near fossil storage cabinets are potentially exposed to radon gas in excessof the EPA recommendations for private residences, while field employees are potentially exposed to hotenvironments beyond what is recommended by NIOSH or the American Conference of GovernmentalIndustrial Hygienists (ACGIH). Recommendations for protecting employees from these hazards arepresented on pages 20-21 of this report.

Keywords: SIC Code 3281 (Cut Stone and Stone Products), museum, excavation, paleontology, fossil, naturalhistory specimen, uranium, radium, radon, ionizing radiation, heat stress, silica, PNOC, PNOR, particulates,National Park Service, National Monument

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TABLE OF CONTENTS

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

Acknowledgments and Availability of Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Site Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Geology & Paleontology Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Process Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Excavation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Storage and Exhibition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Other Site Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Ionizing Radiation Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Gamma Spectrometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Radon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Real-Time Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Passive Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Ionizing Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Environmental Conditions and Heat Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Bulk Samples - Crystalline Silica Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Respirable Airborne Crystalline Silica . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Respirable Airborne Dust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Total Airborne Dust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Local Exhaust Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Evaluation Criteria and Toxicology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Radon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Ionizing Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Heat Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Respirable Crystalline Silica . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Respirable and Total Airborne Dust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Local Exhaust Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Gamma Spectrometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Radon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Real-Time Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Passive Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

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Ionizing Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Heat Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Bulk Silica . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Respirable Crystalline Silica . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Respirable Airborne Dust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Total Airborne Dust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Local Exhaust Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Gamma Spectrometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Radon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Ionizing Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Heat Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Bulk Silica . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Respirable Crystalline Silica . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Respirable and Total Airborne Dust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Local Exhaust Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Gamma Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Radon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Ionizing Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Heat Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Respirable Crystalline Silica . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Respirable and Total Airborne Dust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Local Exhaust Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Radon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Ionizing Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Heat Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Local Exhaust Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Other

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Appendix Uranium Decay Series, 238U . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Abbreviations and Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

INTRODUCTIONOn September 5, 1996, the National Institute forOccupational Safety and Health (NIOSH) received aletter from the Hagerman Fossil Beds NationalMonument (HAFO), requesting technical assistancein the evaluation of gamma radiation and radon gasexposures to HAFO staff.1 HAFO is a unit of theNational Park Service (NPS) in the United StatesDepartment of the Interior, and is located nearHagerman, Idaho. Activities at HAFO include theexcavation, preparation, storage, and exhibition ofvertebrate fossils. The request stated that “. . .(HAFO) has recently determined that some of thefossil materials that we work with on a reoccurringbasis have potential for radon gas and gammaradiation exposure.”

Subsequent communications from HAFO revealedthat the general public, including children, couldview and handle fossils in the Visitor Center.Furthermore, during the summer dig season, HAFOstaff was comprised primarily of seasonalemployees, students, and volunteers, with relativelyfew permanent NPS employees.

In communicating with HAFO personnel prior to theinitial site visit, NIOSH investigators recognizedother potential occupational hazards such as heatstress and airborne silica. HAFO staff concurred,and the scope of the investigation was expanded.Two site visits (May 14-15 and July 23-24, 1997)were conducted, and an interim letter containingrecommended changes in practices and hazardabatements was sent after each visit.2,3 This finalreport contains the major points of those letters aswell as additional information.

BACKGROUND

Site DescriptionThe site is located in Gooding County, Idaho, aboutthirty miles northwest of Twin Falls. The two mainHAFO buildings are located in the town ofHagerman (elev. 2960 ft), on the east bank of theSnake River.4 Rented space in other local buildings

is used for storage of equipment, materials, and rawand prepared fossils.

The Visitor Center consists mainly of exhibitionspace, but also includes offices and a smallauditorium (Figure 1). The exhibition space andauditorium are open to the public and are oftenvisited by groups of students.

The Administration Building contains offices, afossil preparation laboratory, and collections (fossils)storage areas (Figure 2). Included in the preparationlaboratory are two small ventilation hoodsconstructed by site personnel. These hoods areenclosed on all six sides, with hinged tops forplacing/removing fossils and arm holes for access tothe work. The hoods are used to control dust duringfossil preparation and to control odors during therendering (boiling the flesh off) of contemporaryanimal skeletons. A household refrigerator/freezer isused to store animal carcasses prior to rendering (asis a large chest freezer in a rented building). A55 gallon drum of granular Butvar® (poly[vinylbutyral-co-vinyl alcohol-co-vinyl acetate]) is storedin the laboratory, as are small (< 1 gallon) quantitiesof isopropyl alcohol and acetone. Two collectionscabinets are also present in the preparationlaboratory. In the storage room (approximately 8' x12'), adjacent to the laboratory, are twelve morecollections cabinets. These airtight cabinets,approximately 34" x 34" x 30" (H x W x D), areused to protectively store fossils. The bulk of the monument consists of 4281 acres,stretching seven miles along the west bank of theSnake River.4 Elevations range from approximately2800 feet (river level) to 3500 feet. There is virtuallyno level ground within the site boundaries and theslopes are prone to landslides. Annual average rainfall is less than 10", the soil is dusty and sandy, andsagebrush is the predominant vegetation.Rattlesnakes and scorpions are indigenous to thearea. Remnants of the Oregon Trail cross thesouthern end of the monument. There are currentlyno hiking trails within the site. Most visitor andemployee activity is concentrated in a small areaknown as the “Horse Quarry,” located near FossilGulch at the north end of the monument.

Although the Horse Quarry is directly across theSnake River from Hagerman, the location of the

Health Hazard Evaluation Report No. 96-0264-2713

nearest bridge necessitates a fifteen mile drive. Aprivately-owned, half-mile long two-track roadterminates at a small parking lot on the canyon rim,where employees leave their vehicles. Nearby is asmall trailer, occupied at night to deter vandalism. Aportable restroom is also kept on the parking lot.Behind a locked gate is a narrow lane crossing asaddle to the Horse Quarry. Vehicles are sometimesused to carry equipment, but employees generallywalk from the parking lot to the site, approximately200 yards.

The Horse Quarry is a two level terrace cut into theside of a hill. The upper level, approximately 5 yardswide and 30 yards long, is the active dig area. Thelower level, which dips about six feet lower than thefloor of the dig area, is about 10 x 40 yards andincludes a large wooden lock box for secureequipment storage. Weather is typically sunnyduring the May to September dig season so atarpaulin is strung up to provide shade. The averagelate July high and low temperatures are 94° and56° F, respectively.5

Geology & PaleontologyReviewThe 600 foot bluffs rising above the Snake Riverexpose sediment layers ranging in age from 3.15 to3.7 million years.4 This time period is known as thePliocene Epoch of the Cenzoic Era (dinosaursbecame extinct during the Paleocene Epoch,65 million years ago). Some sediment layers containfossilized remains of prehistoric plants and animals.One particular layer, mined at the Horse Quarry,contains many types of fossils: plant and animal,terrestrial and marine, and amphibian and mammal.The site is famous for the large number of wellpreserved skeletons of the Hagerman Horse (Equussimplicidens). Due to the chemical composition ofbones, they tend to concentrate certain radioisotopesduring fossilization and become much moreradioactive than the surrounding soil. This has beendemonstrated previously in dinosaur skeletons,whale vertebrae fossils, and fossilized turtleshells.6,7,8

PROCESS DESCRIPTION

ExcavationThe main process at HAFO can be broken down intofour steps: excavation, preparation, storage, andexhibition of fossils. The first step in the process isexcavation. The soil and sediment layers(overburden) on top of the fossil-bearing layer mustbe removed. Much of the overburden at the HorseQuarry was removed with heavy equipment, but toprotect the fossils the remainder must be removedusing hand tools. Soft soil is shoveled into awheelbarrow and dumped at the edge of the dig site.Harder material is broken up with a Pulaski, a type ofpickax. This work is physically demanding and caremust be taken to avoid destroying fossils.Sometimes the salvage pile (previously removedoverburden) is sifted through a wire mesh to retrievesmall fossils or pieces of fossils. This sifter is aboutthree feet square and mounted three feet high like atable top upon four legs.

After the overburden has been removed and targetfossils are exposed, they are catalogued and theirlocation and orientation are determined using acomputerized laser transit (such as those used byland or road survey teams). Material covering thefossil is delicately removed by hand. When thematrix (rock and soil surrounding the fossil) is softand sandy it is removed with a small paintbrush orsimilar brush. Firmer matrix is cleared away with ahand trowel. Harder material may require a smallhammer and chisel, while dental picks and similartools are sometimes used for the most delicate work.This excavation phase is slow and tedious. Brokenbones are often glued together with a solution ofButvar® in isopropyl alcohol. (Isopropyl alcohol isused as the solvent because acetone evaporates tooquickly outdoors).

Bones and other fossil materials are usually notcompletely extricated at the dig site. Instead,material around and underneath the target is removeduntil a lump of fossil and matrix sits upon a pedestal.Plaster-soaked burlap strips are then wrapped around

Health Hazard Evaluation Report No. 96-0264-2713 Page 3

the target to protect and strengthen it. After theplaster has hardened the lump is detached from thepedestal and transported back to the preparationlaboratory.

PreparationThe second step in the process, preparation, takesplace in the preparation laboratory. Here the plastercast and the rest of the matrix are removed from thefossil. Small hammers and chisels, dental picks, andother hand tools are used to perform this work. Anair scribe (a pen-sized reciprocating chipper drivenby compressed air) is sometimes used as well. Atable, desk, and bench top are available as workareas, as are the two ventilated hoods. The air scribeis always used in one of the hoods. A solution ofButvar® in acetone is used to fix broken bones, andis painted on the surface of all bones to improvestrength and durability. (Acetone is used as thesolvent indoors because isopropyl alcohol evaporatestoo slowly.) Fossil preparation is often performedon a sheet of cardboard, so soil and rock removedfrom the fossils can be dumped into a container fordisposal. Alternatively the removed matrix is sweptup (dry) with whisk brooms and dustpans, cleanedup with damp cloths or sponges, or removed with avacuum cleaner.

Storage and ExhibitionThe third and fourth steps in the process are storageand exhibition. Many fossils are stored in thecollections cabinets in the collections room andpreparation laboratory of the AdministrationBuilding. Additional collections cabinets are kept inthe rented satellite building. The assembledskeletons and individual bones on permanent displayat the Visitor Center are either contemporary bonesor casts of fossils. The practice of not exhibiting theactual fossil bone is common to many museums.9The HAFO Visitor Center does keep somemiscellaneous fossil bones and bone fragmentsavailable for children to handle.

Other Site Activities

Three NPS Rangers are employed at HAFO tomaintain site security and to perform wildlifemanagement tasks such as tree planting andgroundwater sampling. Currently there are no hikingtrails on the monument, but one is underconstruction. Trail building tasks include hoeing andraking by hand, tilling with a self-propelled powertiller, and installing water bars (half buried logs) tocontrol erosion. The terrain is steep and rugged, andthe worksite is reached by driving about one milealong the edge of the monument (there is no road, a4 wheel drive vehicle is required), then walkingdown a steep incline to the end of the current trail.An alternative route is to take the park road along thebottom of the canyon and hike up to the worksite.

Ionizing Radiation ReviewSome atoms are naturally unstable and releaseenergy to eventually reach more stable, lower energyforms. Atoms that release energy in this way areknown as radioisotopes. The Appendix shows themany steps the most common radioisotope ofuranium (238U) takes to finally reach stable lead(206Pb). Each time a radioisotope undergoes aradioactive transition (also known as a disintegrationor decay) it releases one or more forms of radiation.The activity of a radioisotope can be measured inBequerels (1 Bq = 1 decay per second) or Curies(1 Ci = 3.7 x 1010 decays per second). A Curie is alarge amount of activity, so smaller units likepicoCuries (1012 pCi = 1 Ci) are sometimes moreconvenient to use.

Some important forms of ionizing radiation are thealpha and beta particles and gamma rays (photons)emitted from radioactive decay. These are calledionizing radiation because they can knock electronsout of atoms and molecules, creating electricallycharged particles called ions. This ionization processtransfers energy from the radiation particle or photonto the irradiated material. When people are exposedto ionizing radiation this energy transfer can causechemical and physical changes in human tissue.10

The various types of ionizing radiation differ widely


in their abilities to penetrate tissue, deposit energy,and cause damage.

Alpha particles are made up of two protons and twoneutrons, the same as the nucleus of a helium atom.They are much smaller than a single atom and carrya double positive charge. Alphas travel only a shortdistance (less than a millimeter [mm]) in livingtissue, and thus cannot penetrate the skin. Betaparticles (electrons) carry a single negative chargeand are thousands of times smaller than alphaparticles. They travel longer distances in living tissuethan alpha particles, but can be stopped by a thinsheet of metal (aluminum is typically used). Gammarays have no mass or electrical charge, so they cantravel extremely long distances in human tissue,sometimes completely through the body. Thismeans their energy is deposited over a longer pathand is less likely to cause damage to living tissue.10

Since alpha and beta particles are not verypenetrating, when outside the body they can onlydamage the skin and eyes. They become a concernprimarily when internal exposures occur. Internalradiation exposures occur from inhalation ofradioactive dust, from handling radioactive items(material rubbing off onto a person’s hands,especially into cut or abraded skin), and fromingestion of this material. Internal exposures toalpha or beta particles can damage internal organs.Alpha particles are more dangerous since theydeposit all their energy along a very short path.Since gamma rays are very penetrating, they are aconcern when external exposures occur. An externalexposure is irradiation of an object from a sourcelocated outside of the object.

External exposures are measured in unitsof Roentgen (R) or microRoentgen(1,000,000 :R = 1R). A Roentgen is a measure ofhow much ionization is produced in air by gamma orx-rays. When radiation is absorbed by a person, thequantity absorbed is referred to as the radiation dose.The units of radiation dose are the RoentgenEquivalent Man (REM) or Seivert (Sv). Onehundred REM is equal to one Sv. These units werederived to account for the various types of biological

damage caused by different kinds of ionizingradiations (alpha, beta, gamma, x-rays, neutrons, etc).By using REM and Sv, different kinds of radiationcan be combined into one number for administrativeand legal purposes such as monitoring of allowableradiation exposures. Sometimes smaller units likethe milliREM (1000 mREM = 1 REM) are moreconvenient to use.

METHODS

Gamma SpectrometrySix soil samples and a sample of fossils wereanalyzed to determine concentrations of uranium andgamma emitting uranium progeny (see Appendix).The concentrations of these elements affect themanner in which the fossils should be handled andhow the waste soil might be properly discarded. Thelocations were selected by the investigators torepresent a range of soils that could be used for bothgamma spectroscopy and silica content analyses:

1 - North end of Horse Quarry floor2 - South end of Horse Quarry floor3 - North end of Horse Quarry back wall (fossil-

bearing soil layer)4 - Salvage pile at Horse Quarry5 - Soil removed from fossils (soil originated at

Horse Quarry, sample was gathered atpreparation laboratory)

6 - Ditch near the Snake River Public Access-Hagerman side (East bank) of river.

Soil samples were collected by scoopingapproximately 500 cubic centimeters (cm3) ofsurface soil into a wide-mouth plastic bottle. Plants,stones, and other foreign objects were excluded. Thefossil sample was collected by a park ranger andconsisted of fossil pieces that had washed down thehill below the Horse Quarry.

Data Chem Laboratories Inc (Salt Lake City, Utah)used their standard operating procedures WR-DC-200 and WR-EP-325 to measure and identify gammaemitting isotopes by gamma spectrometry.11,12


Nominal 1 gram (g) samples were counted for240 minutes using Canberra high-purity germaniumgamma spectrometry detectors with a GENIEdata processing system. Canberra NID (nuclideidentification) software was used for data analysis.In the practice of gamma spectrometry the limit ofdetection (LOD) is generally expressed relative to areference isotope such as Cs-137. The LOD was0.1 pCi activity per gram of sample (pCi/g) for soilsamples, and 0.5 pCi/g for the fossilized bonesample.

Radon

Real-Time Measurements

Hourly measurements of radon gas concentration inthe collections room, preparation laboratory, and thereception area of the Administration Building wereobtained using the Pylon AB-5 Monitor (PylonElectronics, Ottawa, Ontario). The AB-5 monitor isa portable instrument which uses a 272 milliliter(mL) volume Lucas cell coated internally with zincsulfide.13 The unit counts the number of radondaughter decays during a specific period (one hour inthis instance), corrects for background effects, andcalculates an average radon concentration. The LODof this method is about 0.1 pCi activity per liter of air(pCi/L).

Passive Measurements

Long term average radon concentrations wereobtained using alpha-track detectors provided byLandauer, Inc. (Glenwood, Illinois) and AlphaSpectra, Inc (Grand Junction, Colorado). Thesepassive detectors contain a polymer film inside aperforated metal container. Radon diffuses into thecontainer and decays into electrically chargeddaughter products, which stick to the polymer film.When the radon daughters decay, they createmicroscopic tracks on the polymer. These trackswere counted and converted to an average radonconcentration. The LOD of this method is30 pCi/L/day (the equivalent of 30 days at 1 pCi/L,or 15 days at 2 pCi/L, etc). The detectors were

exposed for 70 days, which converts to a minimumdetectable concentration (MDC) of 0.43 pCi/L.

Ten locations in the Administration Building andfour in the Visitor Center were monitored betweenMay 14 and July 23, 1997. Detectors were attachedto the wall approximately five feet above the floor,except for the three placed inside fossil storagecabinets (see Figures 1 and 2).

Ionizing RadiationPotential sources of exposure to external and internalionizing radiation were evaluated with direct readingsurvey instruments. These included the Victoreen450P (Victoreen, Cleveland, Ohio) pressurized ion-chamber and the Ludlum 2350 data logger with theLudlum model 44-6 (pancake) and 43-65 (alphascintillation) probes (Measurements Inc.,Sweetwater, Texas). The Victoreen 450P was usedbecause of its relatively uniform response to variousgamma energies emitted by the daughter products inthe uranium decay chain (Appendix). Externalgamma-ray dose rate measurements were performedat the Horse Quarry and other locations, and a surveywas performed in the Administration Building (sevenmeasurements) and the Visitor Center (fivemeasurements). The Ludlum 2350 was used tomeasure radiation levels at the surface of the fossils.This instrument was also used to determine levels ofalpha emitting and beta/gamma emitting surfacecontamination on desks, tables, bench and countertops, and floors. A surface survey contaminationsurvey was performed in the AdministrationBuilding (nine measurements) and in the VisitorCenter (five measurements).

Lithium fluoride thermoluminescent dosimeters(TLDs) were used to monitor external exposures toionizing radiation. Workers who excavated,prepared, and/or handled fossils wore two types ofTLDs during their normal work schedules for up toten weeks (May 14 to July 23, 1997). Ring badgesworn on the finger were used to evaluate potentialexposure to the hands. Whole-body badges wornbetween the neck and waist were used to evaluatepotential whole-body exposures. Fifteen pairs of


TLDs were acquired from Landauer, Inc., alaboratory accredited by the National VoluntaryLaboratory Accredited Program (NVLAP). TheTLDs were also analyzed by Landauer, with a limitof detection for each dosimeter of about 10 mREM.

Environmental Conditionsand Heat StressIndoor and outdoor environmental conditions wereassessed with a Psychro-Dyne® psychrometer(Environmental Tectonics Corp., Southampton,Pennsylvania) which measured wet- and dry-bulbtemperature. The dry bulb temperature is simply thestandard measure of air temperature taken with athermometer or similar instrument, while the wetbulb temperature is taken with a wetted-wickthermometer which allows for evaporative cooling.These data were used with a psychrometric chart tocalculate the relative humidity (RH).

A Reuters-Stokes RSS 214 Wibget® heat stressmeter (I&ST Canada Inc, Cambridge, Ont.) was usedto measure the outdoor wet-bulb-globe temperature(WBGT). The WBGT is derived from the naturalwet bulb-, dry bulb-, and globe temperatures. Theglobe temperature, measured with a thermometerplaced in the center of a standard black-matte sphere,estimates radiant (infrared) heat load. The WBGT(external heat load), metabolic heat due to work(internal heat load), and an employee’s clothinginsulation value are used to estimate the amount ofheat stress (environmental heat load) an employee isunder. This estimate of heat stress is used to assessheat strain (physiological load) and determine whatprecautions are necessary to minimize the possibilityof heat disorder.14

Bulk Samples - CrystallineSilica ContentThe six soil samples described previously (GammaSpectroscopy section) were also analyzed forcrystalline silica content. These were analyzed forquartz and cristobalite by Data Chem Laboratories

Inc. NIOSH Method 7500 (Silica, Crystalline, by X-Ray Diffraction) was used with the followingmodifications: standards and samples were runconcurrently and an external calibration curve wasprepared from the integrated intensities rather thanusing the suggested normalization procedure.15

Samples were ground and screened to less than38 micrometers (:m) in size and quantitated with30 mm minusil standards. Polyvinyl chloride (PVC)filters, loaded with 2 milligrams (mg) portions ofbulk material, were dissolved prior to analysis usingtetrahydrofuran (sample preparation option c ofMethod 7500). The LODs were reported as 0.8%(by mass) for both quartz and cristobalite, whilelimits of quantitation (LOQ) were reported as 1.5%for both substances.

Respirable AirborneCrystalline Silica Seven outdoor workers were monitored a total of tentimes to assess possible exposures to respirablecrystalline silica. In compliance with NIOSHMethod 7500 (Silica, Crystalline, by X-RayDiffraction), personal sampling pumps (SKC model224-PCXR8) were used to pull 1.7 liters of air perminute (L/min) through 10 mm nylon cyclonesfollowed by tared 5 :m PVC filters.15 Filters wereobtained from the NIOSH Measurement ResearchSupport Branch Laboratory. Pumps were calibratedat the Hagerman Valley Inn (0.5 mile from HAFOAdministration Building) before and after use with aGilibrator® electronic bubble meter. Sampling wascarried out for full shifts (approximately eight hours).The pumps were enclosed in plastic bags tominimize the potential for radioactive contamination,as sampling was carried out before the source ofradioactivity was identified. For each of the10 samples, the worker’s right or left lapel wasarbitrarily chosen as the location for the samplinghead.

Analyses of the sample filters were performed byData Chem Laboratories Inc. using NIOSH Method7500 (Silica, Crystalline, by X-Ray Diffraction) withthe modifications noted in the previous section.15


The LOD’s were reported as 0.01 mg for quartz and0.02 mg for cristobalite. These correspond to aMDC of 0.01 milligrams per cubic meter (mg/m3) forairborne respirable quartz and an MDC of0.02 mg/m3 for airborne respirable cristobalite (foran ideal 8.0 hr, 1.7 L/min. sample). The LOQ wasreported to be 0.030 mg for both substances, whichwould correspond to a minimum quantifiableconcentration (MQC) of 0.037 mg/m3 for an 8.0 hr,1.7 L/min. sample.

Respirable Airborne DustThe filters used with the cyclones were weighed todetermine the mass of respirable dust prior toanalysis for respirable silica content. NIOSHMethod 0600 (Particulates Not Otherwise Regulated[PNOR], Respirable) was followed, except that themean of two weighings was used in place of a singleweighing of each filter.16 Filters were analyzed byData Chem Laboratories Inc. The LOD was reportedas 0.02 mg, which corresponds to a respirable dustconcentration of 0.02 mg/m3 for an 8 hr, 1.7 L/min.sample.

Total Airborne DustTwelve personal breathing zone (PBZ) and two areasamples were taken to assess exposures to totalairborne dust. A wide variety of job types, activities,and work locations was included among thoseworkers monitored. NIOSH Method 0500 (PNOR,Total) was followed, except that the mean of twoweighings was used in place of a single weighing ofeach filter.17 Sample collection equipment andprocedures were the same as above except that nocyclones were used, and the flow rate was 2.0 L/min.Filters were analyzed by Data Chem LaboratoriesInc. The reported LOD was 0.02 mg, whichcorresponds to a dust concentration of 0.02 mg/m3

for an ideal 8.0 hr, 2.0 L/min. sample.

Local Exhaust VentilationAir velocity measurements were made using aVelociCalc® Model 8360 (TSI Inc., St. Paul, MN)

Air Velocity Meter. This instrument is a constanttemperature thermal anemometer whichautomatically compensates for changes in air densitydue to variations in temperature or barometricpressure. All velocity measurements are given instandard feet per minute. TSI defines standardconditions as 70° Fahrenheit (F) and 14.7 pounds persquare inch, absolute.18

Measurements were made with the hood lids closedand no workers in place. The mean of several (6-20,depending on cross-section area) air velocitymeasurements was used. Volumetric flowrates werecalculated using the product of the velocity and theappropriate cross-section area. Hood application,configuration and materials of construction, andappropriateness of the system fan were alsoevaluated using the American Conference ofIndustrial Hygienists’ Industrial Ventilation: AManual of Recommended Practice, 20th edition.19

EVALUATION CRITERIAAND TOXICOLOGY

As a guide to the evaluation of the hazards posed byworkplace exposures, NIOSH field staff employenvironmental evaluation criteria for the assessmentof a number of chemical and physical agents. Thesecriteria are intended to suggest levels of exposure towhich most workers may be exposed up to 10 hoursper day, 40 hours per week for a working lifetimewithout experiencing adverse health effects. It is,however, important to note that not all workers willbe protected from adverse health effects even thoughtheir exposures are maintained below these levels. Asmall percentage may experience adverse healtheffects because of individual susceptibility, apre-existing medical condition, and/or ahypersensitivity (allergy). In addition, somehazardous substances may act in combination withother workplace exposures, the general environment,or with medications or personal habits of the workerto produce health effects even if the occupationalexposures are controlled at the level set by thecriterion. These combined effects are often not


considered in the evaluation criteria. Also, somesubstances are absorbed by direct contact with theskin and mucous membranes, and thus potentiallyincrease the overall exposure. Finally, evaluationcriteria may change over the years as newinformation on the toxic effects of an agent becomeavailable.

The primary sources of environmental evaluationcriteria for the workplace are: (1) NIOSHRecommended Exposure Limits (RELs),20 (2) theAmerican Conference of Governmental IndustrialHygienists' (ACGIH®) Threshold Limit Values(TLVs®),14 and (3) the U.S. Department of Labor,Occupational Safety and Health Administration(OSHA) Permissible Exposure Limits (PELs).21

NIOSH encourages employers to follow the OSHAlimits, the NIOSH RELs, the ACGIH TLVs, orwhichever are the more protective criterion. TheOSHA PELs reflect the feasibility of controllingexposures in various industries where the agents areused, whereas NIOSH RELs are based primarily onconcerns relating to the prevention of occupationaldisease. It should be noted when reviewing thisreport that employers are legally required to meetthose levels specified by an OSHA standard.

A time-weighted average (TWA) exposure refers tothe average airborne concentration of a substanceduring a normal 8- to 10-hour workday. Somesubstances have recommended short-term exposurelimits (STEL) or ceiling values which are intended tosupplement the TWA where there are recognizedtoxic effects from higher exposures over theshort-term.

RadonRadon is a colorless, odorless, tasteless, radioactivegas. The chemical symbol for radon is Rn, and it hasan atomic weight of 222 grams per mole. 222Rn isformed from the radioactive decay of radium(226Ra), which is part of the 238U decay chain (seeAppendix). 226Ra and 238U are present in most

soils and rocks, though the concentration of theseradionuclides varies widely. Since radon is a gas itcan leave the soil or rock where it formed and enterthe surrounding air. High airborne concentrations ofradon can build up when ventilation rates are low orwhen a large amount of 226Ra is present. As shownin the Appendix, radon decays with a half-life ofabout four days into a series of solid phase(particulate), short-lived radioisotopes commonlycalled radon daughters or progeny. These progenycan electrostatically adhere to suspended dustparticles and remain airborne for extended periods oftime. Two radon progeny (218Po and 214Po) emitalpha particles. If these radionuclides are inhaled thealpha radiation can damage the cells lining theairways, and the resulting cellular changes canultimately lead to lung cancer.22

Cancer is the major effect of concern from theradium and radon radionuclides.22,23 TheEnvironmental Protection Agency (EPA) hasclassified radium as a Group A human carcinogen,but has not classified radon for carcinogenicity.Inhalation is the primary route of radon exposure.Exposure to radon increases a person’s risk for lungcancer, and smokers exposed to radon are at greaterrisk for lung cancer (approximately 10 to 20 times)than are similarly exposed nonsmokers.22 Long termexposures to high levels of radon (on the order of100 pCi/L for 10 years) can also cause non cancerdiseases of the lungs, such as thickening of certainlung tissues.22 No information is available on theacute (short-term) effects of radon in humans.Exposure for one day to a radon concentration of2.2 x 108 pCi/L was lethal to mice.22

Background levels of radon in outdoor air range from0.003 to 2.6 pCi/L and are higher in areas withuranium and thorium deposits or graniteformations.20 Higher levels of radon are frequentlypresent in indoor locations such as homes, schools,or office buildings. Indoor radon levels are usuallyabout 1.5 pCi/L, although much higher levels(>200 pCi/L) have been measured in homes acrossthe country. The EPA recommends that correctivemeasures be taken when in-home radon levelsexceed 4 pCi/L. Outside of certain mining


industries, radon is generally not considered anoccupational hazard. Other than in these miningindustries, no occupational exposure limit(mandatory or recommended) has been establishedfor radon.

Ionizing RadiationThe current occupational exposure standard from theNuclear Regulatory Commission (NRC) is 5 REMper year above background for radiation workers.24

This limit is not applicable to the NPS for tworeasons: NPS workers are not regulated by the NRC,and the exposures are from naturally occurring (andthus unregulated) radiation sources. A moreappropriate NRC standard that can be applied toHAFO workers is the annual dose from ionizingradiation permitted to members of the public:0.1 REM or 100 mREM above background. Anotherlimit that may be applied is the InternationalCommission of Radiological Protection (ICRP)recommended limit for protecting against ionizingradiation in the teaching of science.25 The ICRPrecommends that student doses be limited to50 mREM per year above background.

Heat StressExcessive exposure to hot environments can lead to(in increasing order of severity) skin disorders, heatsyncope (fainting), heat cramps, heat exhaustion, andheat stroke.26,27 Persons at greatest risk are non-acclimatized workers, obese people, the elderly,people with cardiovascular or circulatory disorders,those taking medications that impair the body’scooling mechanisms, people performing physicallystrenuous work, people who use alcohol (or arerecovering from recent use), and individualsrecovering from illness.

Skin disorders such as heat rash and hives are causedby excessive sweating or retention of sweat.26,27 Inheat syncope, fainting results from blood flow beingdirected to the skin for cooling, resulting indecreased supply to the brain. This disorder oftenstrikes workers who must stand in place for extended

periods in hot environments. Heat cramps, causedby sodium depletion due to sweating, typically occurin the muscles employed in strenuous work.

Heat cramps and syncope often accompany heatexhaustion.26,27 The weakness, fatigue, confusion,nausea, and other symptoms of this disordergenerally prevent a return to work for at least24 hours. The dehydration, sodium loss, andelevated core body temperature (above 100.4° F) ofheat exhaustion are usually due to individualsperforming strenuous work in hot conditions, withinadequate water and electrolyte intake. Heatexhaustion may lead to heat stroke if the patient isnot quicky cooled and rehydrated.

While heat exhaustion victims continue to sweat astheir bodies struggle to stay cool, heat stroke victimscease to sweat as their bodies fail to maintain anappropriate core temperature.26,27 Heat stroke occurswhen hard work, hot environment, and dehydrationoverload the body’s capacity to cool itself. Thisthermal regulatory failure (heat stroke) is a life-threatening emergency requiring immediate anddecisive medical attention. Symptoms includeirritability, confusion, nausea, convulsions orunconsciousness, hot dry skin, and a core bodytemperature above 106° F. Death can result fromdamage to the brain, heart, liver, or kidneys.

ACGIH has developed TLV®s which represent“heat stress conditions under which it is believed thatnearly all heat acclimatized, adequately hydrated,unmedicated, healthy workers wearing light-weightsummer clothing may be repeatedly exposed withoutadverse health effects.”14 Further assumptionsinclude an 8 hour work day, 5 day work week, two15 minute breaks, and a 30 minute lunch break, withrest areas and work areas at the same temperatureand “at least some air movement.” By taking intoaccount a workers’ sources of heat (work, airtemperature, radiant heat [sunlight]) and the abilityof the body to cool itself (clothing insulation value,humidity, wind), a schedule of rest periods can berecommended. These work/rest regimens (Table 1)are designed to maintain workers’ core bodytemperatures below 100.4° F.


NIOSH has developed separate RELs for workerswho are not acclimated to hot environments (Figure3) and for workers who are acclimated to hotenvironments (Figure 4).27 When these work/restregiments are followed, nearly all workers should beable to tolerate the resulting total heat exposureswithout substantially increasing their risk of acuteadverse health effects. This statement assumes thatworkers are medically and physically fit for the levelof activity required for their job, and are wearing atmost long-sleeved work shirts and trousers.

Respirable Crystalline SilicaSilicon dioxide (SiO2), also known as silica, occursin both crystalline and amorphous forms.Amorphous (non-crystalline) silica is regarded asless hazardous and will not be discussed here.28,29 Ofthe three primary forms of crystalline silica (quartz,cristobalite, tridymite), quartz is the most common.Quartz is commonly found in igneous rocks such asgranite, as well as sedimentary rocks like sandstone.Quartz occurs in large amounts in sands and soils.Quartz has no odor and is colorless when pure.Inhalation of quartz dust has been recognized forcenturies as the cause of silicosis. Only the smallestdust particles, those less than 10 :m aerodynamicdiameter, can penetrate deep into the lungs to causesilicosis. Dust smaller than 10 :m is calledrespirable dust because of its ability to enter the deep(gas exchange region) of the lung.

Silicosis is an example of a class of dust inducedlung diseases called pneumoconioses. The threeclinically distinct forms of silicosis are termedchronic, accelerated, and acute.28,29 Chronic silicosisis distinguished by the formation of characteristiclumps of scar tissue in the lungs. Initially the victimmay have no symptoms of the disease, but the lumpsmay continue to grow and/or join together. Thus thedisease may progress for many years, even afterexposures to crystalline silica have ceased. Typicalsymptoms include cough, shortness of breath, andwheezing, and the disease is sometimes fatal. In pastdecades the development of associated tuberculosiskilled many victims. Acute silicosis is often fatalwithin a year, and accelerated silicosis within a few

years of exposure, but these are diseases that strikesandblasters and other highly exposed workers. Allforms of silicosis occur following exposures to muchhigher respirable crystalline silica concentrationsthan observed at HAFO. Silicosis is 100%preventable.

NIOSH believes that crystalline silica should betreated as a potential occupational carcinogen.15 TheIARC includes crystalline silica in group 2A(probably carcinogenic in humans).29 The NationalToxicology Program (NTP) classifies crystallinesilica as a Group 2 Carcinogen (reasonablyanticipated to be a carcinogen), but has not yetstudied the carcinogenicity of this substance. TheACGIH has declared that there is insufficientevidence to decide whether crystalline silica is acarcinogen, and OSHA does not regulate crystallinesilica as a carcinogen.

The NIOSH REL for quartz is 0.05 mg/m3

(respirable fraction), while the ACGIH TLV® forquartz is 0.1 mg/m3 (respirable fraction).28,29 TheOSHA PEL for respirable crystalline silica is basedon the formula:

PEL = (10 mg/m3) / (% SiO2 + 2).21

When the material is 100% silica, the PEL is0.098 mg/m3, nearly equivalent to the TLV®.

Respirable and TotalAirborne DustExcessive concentrations of dust in the air canreduce visibility; mechanically irritate the eyes, ears,nose, and throat; and increase susceptibility todisease or chemical toxins by contributing to injuryof skin and mucus membranes.30 OSHA haspromulgated a PEL of 15 mg/m3 for total PNOR and5 mg/m3 for respirable (smaller than 10 mm)PNOR.21 ACGIH recommends that exposures torespirable Particulates Not Otherwise Classified(PNOC) not exceed 3 mg/m3.14 The definitions ofPNOR and PNOC exclude materials containinggreater than 1% crystalline silica. Since the dusts at


HAFO are known to contain greater than 20%crystalline silica, these evaluation criteria are notdirectly applicable to the sample results of thissurvey. They are presented here to provideperspective to the total dust sampling results and toaid in assessing the overall dustiness of theworkplaces at HAFO.

Local Exhaust VentilationEvaluation criteria were obtained from the ACGIHIndustrial Ventilation: A Manual of RecommendedPractice, 20th edition.19 The hoods were evaluated ascustom made enclosing type hoods, utilized tocontrol low toxicity materials associated with workthat may be described as hand grinding operations.The specific print number used to assess theapplication was VS-412 (Figure 8).

ACGIH recommends a minimum face velocity of100 feet per minute (fpm), and a volumetric flow rateof 150 - 250 cubic feet per minute (cfm) per squarefoot of hood floor area.19 General designconsiderations from the Ventilation Manual, coupledwith the nature of the contaminants generated in thefossil laboratory, were also considered in evaluatingthe hoods’ performance.

RESULTS

Gamma SpectrometryThe gamma spectrometry results indicate that the soilat the Horse Quarry was no more radioactive than thesoil from the opposite (Hagerman) side of the SnakeRiver. All soil samples contained less than 1 pCi/g238U in equilibrium with its daughters. A reportedtypical range for igneous and sedimentary rocks is0.2 - 2 pCi/g.31 These analyses also indicated that asample of fossilized material (drawn from thepulverized remains of many separate fossil pieces)contained approximately 700 ± 200 pCi/g of gammaemitting radionuclides. Uranium containingminerals such as uraninite (86,000 - 229,000pCi/gm), euxenite (8400 - 19,500 pCi/g), and

carnotite (18,400 - 28,100 pCi/g) have been found tobe much more radioactive than this.32 It should benoted that individual fossils may widely vary in theirradionuclide concentrations, and this result was anaverage of several different fossils.

Radon

Real-Time Measurements

Figure 5 illustrates hourly radon measurementsrecorded between May 14 and July 11, 1997. Thehourly average radon concentrations and standarddeviations were 7.7 ± 3.4 pCi/L in the collectionsroom, 1.0 ± 0.3 pCi/L in the preparation laboratory,and 0.9 ± 0.3 pCi/L in the reception area.

Figure 6 illustrates the mean hourly average radonconcentration determined for each of the threemonitored areas. Radon concentrations in thepreparation and general administration areasaveraged around 1 pCi/L with minimal variation(<0.3 pCi/L). The collections room data weredivided into work-day and weekend averageconcentrations. The average work-day concentrationwas 7.4 ± 3.8 pCi/L and the average weekendconcentration was 8.2 ± 2.1 pCi/L.

Passive Measurements

Table 2 lists the results from the passive monitoringconducting between May 14 and July 23, 1997. Thethree detectors placed within fossil storage cabinetsmeasured the highest radon concentrations, rangingbetween 128 and 500 pCi/L. The collections room,preparation laboratory, and reception areas measuredaverage radon concentrations of about 8 pCi/L,1.5 pCi/L, and 1.8 pCi/L respectively. Othermonitors in the Administration Building and VisitorCenter measured radon concentrations from belowthe MDC (0.4 pCi/L) up to 2.5 pCi/L.

Ionizing RadiationMost area survey measurements using the Victoreen450P were at or near background radiation levels.


The background rate (about 20 :R/hr) wasdetermined outside the Administration Buildingaway from any known sources of radiation. Theonly indication of slightly above backgroundradiation levels (between 30 and 60 :R/hr) werefound in localized areas in the collections room nextto fossil storage cabinets and at the Horse Quarrynext to fossils being excavated. These rates quicklydropped off to background levels within a foot ortwo from the localized area.

The surface contamination survey found no evidenceof alpha emitting contamination nor any beta/gammacontamination on work surfaces in theAdministration Building or the Visitor Center (seeFigures 2 and 3 for locations). Measurements withthe Ludlum data logger and pancake probe showedthat fossils were more radioactive than soil, a findingconsistent with the gamma spectroscopy results.

Personnel exposures to ionizing radiation weremonitored with ring and whole-body TLDs. Somevolunteers who were monitored began work afterMay 14, 1997, or terminated work before July 23,1997. Not all volunteers worked full time. Thelength of time the TLDs were worn could not bedetermined since work-shift durations varied due toweather conditions, work load, and other factors, anddiaries of activities performed while wearing badgeswere not kept.

All ring dosimeters issued to the workers during thesurvey period (May 14 - July 14, 1997) were belowthe LOD of 10 mREM. Workers’ hands are closestto the source of radioactivity (fossils) for the longestperiod of time, so the hands are the part of the bodymost likely to receive an external dose of radiation.The whole body dosimeters are farther from thesource of radioactivity, so it is unlikely that anywhole-body dosimeter would measure a dose greaterthan the ring dosimeter. One whole body dosimeterdid have a slightly positive result, an inconsistencywhich cannot be explained. The instrument surveydata, coupled with the ring dosimetry results,indicates that external ionizing-radiation is not asignificant hazard at HAFO.

Heat StressWorkers typically wore boots, long pants, lightcolored (sometimes long-sleeved) shirts, and a hatwhen outdoors. The workers generally wore lightcolored cotton clothing, although the U.S. ParkService Ranger uniform is made from heavy materialand has dark pants. No clothing correction was madeto the WBGT, since most workers wore lightsummer clothing as customarily worn by workerswhen working under hot environmental conditions.14

The brushing and troweling of loose soil from fossilbones or using the laser transit can be consideredlight work, according to the ACGIH TLV®booklet.14 Removing hard matrix from a fossil witha hammer and chisel, or carrying equipment andfossils between the Horse Quarry and the parking lotwould constitute moderately intense work. Mosttrail building activities such as raking, hoeing, andusing the power tiller, are heavy work. SimilarHorse Quarry activities, such as moving soil with apickax, shovel, and wheelbarrow, are also heavywork.

Due to a battery problem the Wibget® wasoperational only on July 23, 1997. The highest drybulb temperature measured was 94° F, which is theaverage high temperature for this date.5 WBGTmeasurements were taken at the Horse Quarry fourtimes that day, and these results are plotted in Figure7. Table 1 and Figure 7 indicate that, according tothe ACGIH Heat Stress TLV®, on typical summerafternoons acclimated workers performing heavywork should be allowed to rest one half hour per halfhour worked. An alternative would be to performheavy work in the morning only.

At the Horse Quarry a tarpaulin was pitched like anopen tent, and this was used as a break area. TheWBGT under the tarp was 5° F cooler than the restof the Horse Quarry (74° F vs. 79° F) on theafternoon of July 23, 1997. The hiking trail wasbeing built in an area with no trees or other sourcesof shade, so breaks were taken under the sun. Thepreparation laboratory was located in an air


conditioned building where conditions wereoccasionally uncomfortable but not hazardous.There is no formal heat stress program in place atHAFO - acclimatization, work rates, rest periods, andwater intake are self-paced. No formal buddy-systemexists, but rangers (who have radios linked to thelocal fire and police departments) on security patrolare the only workers alone in the field. All fieldcrews (Horse Quarry, trail building, ranger fieldwork, ranger patrol) maintain radio contact with theadministration building and a cellular phone ispresent at the Horse Quarry if needed.

Bulk SilicaThe soils of the Horse Quarry contained 20-25%crystalline silica (Table 3), indicating that airbornedust likely contained silica. The decision to monitorHAFO personnel for respirable crystalline silica wasbased on these results.

Respirable Crystalline Silica The respirable crystalline silica monitoring resultsare presented in Table 4. A quantifiable amount ofcrystalline silica was detected on only one of tenfilters. Nothing unusual was noted about the tasks orwork habits of the individual with the quantifiablesilica result.

Respirable Airborne DustTable 4 shows that the respirable (smaller than10 mm) airborne dust results were an order ofmagnitude lower than the evaluation criteria for non-silica bearing dusts (5 mg/m3 PEL, 3 mg/m3

TLV®).14,21 It should be noted that the high silicacontent of the bulk samples are an indication that thePNOR and PNOC criteria are not applicable, sincethese criteria do not protect against silicosis. Thesecriteria are indicative of dust levels which wouldpresent housekeeping and mechanical irritationproblems. The highest result was from the cycloneworn next to an invalid total dust filter, so thevalidity of this result remains in doubt.

Total Airborne DustTable 5 displays the results of the total airborne dustmonitoring. All results were an order of magnitudelower than the evaluation criteria (15 mg/m3 PEL),except one invalid filter.21 This filter cassettecontained an excessive amount of loose material, andthe calculated dust concentration (188 mg/m3) wouldbe intolerable to work in. It should be noted that thehigh silica content of the bulk samples are anindication that the PNOR and PNOC criteria are notapplicable to this environment, since these criteria donot protect against health hazards such as silicosis.Instead, these criteria are for dusts which cause onlyhousekeeping and mechanical irritation problems.

Local Exhaust VentilationThe hood located along the east wall of thepreparation laboratory (referred to as the east hood)is an enclosed down draft bench top hood. Thispainted plywood hood has a two part hingedplexiglass top, with the second panel folding down atabout a 45° angle on the front of the hood. Thisopening facilitates the placement and removal offossils in the hood. A sliding front panel has twoarm hole cutouts and can be moved from side to sideto permit access to the entire hood interior. Thishood has six sides (fully enclosed) and the exhausttake-off is located in the back floor of the hood. Aside exhaust takeoff beneath the hood floor isconnected to the fan by a 5.5' section of 6" diameterflexible aluminum duct. The axial fan, installed inthe south exterior wall, is equipped with a metaldischarge cover with flexible wind flap. There is nofilter or other contaminant collection device.

The hood located along the south wall of thepreparation laboratory(referred to as the south hood)is also constructed of plexiglass and plywood. Thishood has two interchangeable plexiglass fronts, onewith two arm holes (for cleaning fossils) and asecond with only a 2" slot along the top (used whenrendering animal carcasses). This hood has only foursides, as the counter top and laboratory wall serve asthe floor and back of the hood. An axial wall fan is


installed in the wall directly at the back of thissecond hood. This fan also has a discharge coverand wind flap, but no filter or contaminant collectiondevice.

The hoods serve primarily to contain dust and smallprojectiles produced while cleaning fossils. Fossilsand fossil fragments may also be varnished or gluedtogether with Butvar® inside of the hoods, butcontrol of these vapors was a secondary use of thehoods. The basic design of the hoods and theincorporation of fundamental contaminant controlprinciples is sound, within the material, space, andresource limitations existing at the time ofconstruction. Face velocities at the access openings(arm holes) to the hoods exceeded an ACGIHrecommended minimum of 100 fpm with no one atthe hood.19 (See Table 6)

The south hood has no duct to allow leaks, so thehood exhaust rate and fan exhaust rate are equal.The latter was measured for convenience incalculating system volumetric flow rate. About 10%of the air exhausted by the east hood fan is due toleakage around the hood; the fan exhausts 149 cfm,while 134 cfm are pulled from the hood. Thevolume of air moving through the hoods per squarefoot of bench area is between 17 and 40 percent ofthe ACGIH minimum recommended flow volumefor portable hand grinding hoods.19 The hoodsadequately enclose the work process, butineffectively collect the primary contaminant,mineral dust. The axial fans in use are not designedfor this application. The low volumetric flow rateand absence of a dust collector prevent the actualcapture, transport, and removal of dust generatedwithin the system.

OtherSeveral HAFO employees were seen wearingearplugs, respirators, gloves, and other personalprotective equipment (PPE), sometimes incorrectly.In some instances PPE was not worn when needed(e.g. safety glasses at the Horse Quarry). There iscurrently no established PPE program, which isnecessary for effective PPE use.

A general site safety training module is currentlyincluded in the new employee orientation, butrecordkeeping of who was trained and what wascovered are inadequate. The Safety Officer has notreceived Collateral Duty Safety Officer trainingrequired by Executive Order 12196.33 This orderrequires all agencies of the Executive Branch tofurnish employees a workplace free of recognizedhazards that may cause death or serious physicalharm. Additional requirements of this ExecutiveOrder include: assurance that periodic inspections ofagency workplaces are performed by personnel withequipment and competence to recognize hazards; andprovision of safety and health training forsupervisory employees, employees responsible forconducting occupational safety and healthinspections, all members of occupational safety andhealth committees where these are established, andother employees.

DISCUSSION

Gamma SpectrometryThe significance of the gamma spectroscopy resultsis that the source of the radioactivity occurs in thefossils, not the soil. The fossil gamma spectroscopyresult can not be interpreted to be representative ofany particular fossil. The sample was not a randomcollection of fossils and only one analysis wasperformed.

RadonFigure 5 and Table 2 illustrate that the highest radonconcentrations occur in the collections room.Elevated radon levels were not found in othermonitored rooms. Factors influencing the high radonconcentrations in the collections room include: (1)the amount of radioactive material in the fossils, (2)the mass of fossils stored in the cabinets, (3) thelength of time the cabinets remain closed (permitting


radon build-up), (4) the frequency and duration thecabinets remain opened (allowing radon release), and(5) the lack of mechanical ventilation of the room.The monitoring data in Table 2 clearly demonstratethat radon concentrations inside the cabinets canbuild-up to levels exceeding 100 pCi/L.

Three observations were made concerning the dailypatterns of radon concentration seen in Figure 6.First, a diurnal pattern was seen as the averagehourly radon concentration increased in the earlymorning to mid-afternoon and then decreased intothe late evening. This pattern is often seen in radonmonitoring results, and is due to barometric pressure,temperature, and wind changing the rate of naturalventilation of the building. Second, the workdayhourly averages show a decrease after 8:00 a.m.which is not seen in the weekend results. Thischange is due to the opening of doors as employeesarrive in the morning, which apparently releasessome of the radon to the outdoors. Thirdly, thework-day average radon concentrations exceedweekend averages for several hours in the earlyafternoon. This is probably due to work activities inthe collections room during a typical work-day. Forexample, workers returning from the Horse Quarrymay open storage cabinets to move, store, or retrievefossils which releases radon into the collectionsroom. The afternoon phenomenon did not appear toaffect the reception area averages. However, thepreparation laboratory, which is the only access tothe collections room, did have concentrations slightlyabove the administration area during this period.

The real-time and passive monitoring data wereconsistent. In the collections room, the real-timemethod measured an average radon concentration of7.7 pCi/L, while the passive detectors measured 8.1and 8.2 pCi/L. In the preparation and reception areasthe real-time measured average radon concentrationswere 1.0 and 0.9 pCi/L, while the passive detectorsmeasured 1.6 and 1.8 pCi/L respectively.

These results may not reflect radon concentrationsduring other times of the year, since data werecollected only during a two month period betweenMay and July 1997, and work activities at HAFO

change with the seasons. This seasonal workloadvariation may substantially change the radonconcentrations inside the administration building,especially in the collections room. Many of theworkers at HAFO are visiting scientists, seasonalworkers, or volunteers who work part time or forshort duration. A more complete evaluation of thepotential radon hazard at HAFO would requiretracking when and where these transient people workas well as seasonal radon monitoring.

A comparison to the EPA recommendationsregarding radon exposures can be used to illustratethe degree of hazard present at HAFO, keeping inmind that the EPA recommendations concern radonconcentrations in the home. The EPA recommendsthat remedial actions be initiated when the averageradon concentration level exceeds 4.0 pCi/L.22 Sincethe collections room is the only location exceedingthis limit, it would be recommended for remedialaction. The source of radon in this room is fromradioactive fossils in the collections cabinets, soremedial efforts should focus here.

In the practice of industrial hygiene, health hazardsare abated with administrative controls, engineeringcontrols, and use of personal protective equipment.Several mineral museums have reduced radonexposures with administrative controls such asstoring uranium-bearing minerals in unoccupiedareas and restricting access to these areas. Whilethese policies may be applicable to HAFO, they relyon human behavior and only reduce the duration (notthe intensity) of exposure. Engineering controls arepreferred as the primary means of hazard controlsince they do not necessarily rely upon humanbehavior and can reduce the intensity of exposure.

One engineering control used in mineral museums tocontrol radon levels would be to move all fossilstorage cabinets to a dedicated room with dedicatedventilation exhausted to the outdoors.32-38 This couldbe accomplished by installing a fan in the exteriorwall of the collections room and an air supply gratein the door (to prevent air starvation of the fan).Lambert suggested 3-4 air changes per hour, whichwould be about 75-100 cfm for a collections room


estimated as 6' x 8' x 30'.34 The required ventilationrate will depend on the desired control level and theradon generation rate, which in turn will bedetermined by the mass of fossils stored, the amountof radium in the fossils, and the radon emanationfraction (proportion of radon that exits the fossil).The radon emanation fraction of processed fossilsmight be reduced by applying one or more coats ofButvar® to the surface of the fossils after all thematrix has been removed.

The most effective control would be to provideexhaust ventilation for individual storage cabinets,since this would control the radon at its source. Thiscould be accomplished with a single fan connected toeach cabinet via a manifold. A continuously runningsystem would be simpler, but a purge system(operated immediately before opening a cabinet)might be desirable due to fossil preservationconcerns. A purge-before-open system might alsorequire an interlock system to prevent the opening ofunpurged cabinets. Designing a manifold exhaustventilation system into a new building would likelybe easier and more cost effective than retro-fitting asystem to the current building.

Ionizing RadiationThis initial survey was performed to determinewhether external radiation exposures at HAFOpresent a significant health hazard. The surveyinstruments, ring badges, and whole body badgesindicated that external radiation exposures at HAFOwere low. No explanation could be found for thesingle positive whole body badge, since the sameworker’s ring badge (like all of the ring badges) didnot detect any radiation exposure to the hands, andthe hands are closer to the radiation sources (fossils)than the whole body badge worn on the chest.

Since the soil does not contain elevated levels ofradionuclides, inhalation and ingestion of soil dustare not routes of internal radiation exposure.Workers take great care to avoid damaging thefossils while cleaning them, so matrix removedduring this process contains little or no fossilmaterial. No special precautions to minimize

internal radiation exposure need be taken whenhandling the matrix removed from the fossils.

The fossilized bones contain radioactive elementsfrom the uranium decay series (Appendix). Internalradiation exposures could theoretically occur fromdirect handling of fossils (material rubbing off ontoa person’s hands), from ingestion of this material, orfrom inhalation of airborne fossil dust. Due to thecare taken when cleaning the fossils, very little fossilmaterial is removed and airborne fossil dust isnegligible. Furthermore, the hoods contain airbornedust when fossils are cleaned inside them. Also,current good laboratory practices (washing of handsafter handling fossils and prohibiting food and drinkin fossil handling areas) will interrupt the otherinternal exposure pathways. For these reasons, andsince no detectable surface contamination was found,internal radiation exposures are expected to be low.Any removable radioactivity of processed fossilswould be fixed by applying one or more coats ofButvar® to the fossil surface after the specimen hasbeen cleaned.

Heat StressJuly and August are usually the warmest time of yearin Hagerman, with daily high temperatures in the low90's.5 The number of workers, types of workers,production level, activities, and weather observedduring the July site visit were considered typical forthe time of year. The Horse Quarry and trail sitewere both staffed at normal levels, and no unusualoperations were being performed. Conclusionsdrawn from this visit will be applied to normalconditions during the entire hot season at HAFO,even though all measurements were taken over a twoday period. The workforce at HAFO includes individuals with aknown risk factors for heat disorders (i.e. lack of heatacclimatization). Volunteers, visiting scientists, andother short term workers may only stay for a week ortwo, which is about the time it takes to acclimatize tohot conditions. These people may come from coolerclimates, lead sedentary lives, or have other knownrisk factors for heat disorders. Such people typically


work full shifts from the start of their assignment,with no formal acclimatization schedule. It is unsafeto place them in a hot desert environment, milesaway from medical help, for eight hour shifts ofoutdoor work. The ACGIH heat stress TLV®recommendations are for acclimatized workers, sothey may not be sufficiently protective for all HAFOworkers.14

Figure 7 and Table 1 show that typical summerafternoons at the Horse Quarry are hot enough thatACGIH would recommend workers doing heavywork receive a half-hour of break time per hour. Forworkers not yet adapted to hot conditions,appropriate precaution would be to lower thethresholds for heavy work by 7° F, the thresholds formoderate work by 5° F, and the thresholds for lightwork by 3° F.27 Such precautions would requireextra break time for new workers performingintermediate work in the afternoon, and wouldrestrict new workers from performing heavy work inthe afternoon.

The WBGT was not measured at the trail buildingsite, but since the site is sheltered from any wind(below the canyon rim), this work site may be hotterthan the hilltop Horse Quarry. There are no trees orother sources of shade. Some trail workers worenuisance dust masks which, like any negativepressure respirator, add to heat stress by increasingbreathing resistance and breath recirculation. Mostof the trail building activities are heavy work, soexposures to heat at this worksite probably exceedwhat is recommended by ACGIH. If so, theseworkers have an elevated risk of suffering from oneof the heat disorders described in the EvaluationCriteria and Toxicology section of this report. Theremote location of this worksite would make amedical evacuation difficult and time consuming.

The hot climate, remote locations, and presence ofvulnerable workers at HAFO indicate that a formalheat stress program is necessary. Current practicesat HAFO, such as maintaining radio contact withfield teams, allowing work to be self-paced, anddressing appropriately for hot conditions, should bewritten into a comprehensive heat stress program.

Such a program can stand alone or exist as part of thecurrent health and safety program.

Bulk SilicaThe high crystalline silica content of the soils at theHorse Quarry demonstrates that there is potential forexposures to airborne silica. Components of soildiffer in hardness, density, particle size and otherproperties. Therefore these results do not indicatethat the airborne dust at the Horse Quarry containsthe same amount of crystalline silica as does the soil.

Respirable Crystalline SilicaAirborne dust at HAFO likely contains silica, sincewindblown dust is often visible and the parentmaterial of this dust (soil) is known to contain silica.The hand tools used by HAFO workers are a lowenergy mechanical process, and thus tend to generatelarge particles of dust. In contrast, it is exposure tothe respirable (smaller than 10 :m) crystalline silicaparticles that are a health hazard. Exposures torespirable crystalline silica at the Horse Quarry seemto be low, since only one of nine measurementsdetected a measurable amount of silica. Theseresults indicate that the concentration of respirablecrystalline silica, averaged over the entire workday,was less than the minimum detectable concentration(about 0.01 mg/m3)

Only one worker on the trail building crew wasmonitored for exposure to respirable crystallinesilica, so no conclusions can be drawn. Silicaexposures were not considered to be a concern at thefossil preparation laboratory. This conclusion wasbased upon the low total dust results from airsamples taken during the May 1997 visit, the absenceof windblown dust, and the use of the hoods tocontain airborne dust. No sampling was performedin the preparation laboratory for airborne respirablesilica.

Respirable and TotalAirborne Dust


The dust concentrations measured at the HorseQuarry are unlikely to cause eye, skin, and otherphysical irritation. Extreme conditions could lead todust-induced eye, throat, or other irritation. Indeed,occasionally the Horse Quarry is closed due to highwinds and windblown dust. Other potential sourcesof overexposure are the filling/dumping ofwheelbarrow loads and the sifting of soil. Most ofthe dust at the Horse Quarry seemed to be due to thewind, rather than due to the excavation.

Unlike the Horse Quarry, most of the dust at the trailbuilding site seemed to result from the activities ofthe workers. Using the power tiller was by far thedustiest activity at HAFO. In general industry, wateris often used to control dust, but this is not feasible inthis remote desert location. The dust masks worn bythe trail building crew are an appropriate means ofpreventing nose and throat irritation when worncorrectly by properly trained individuals. Safetyglasses stop projectiles from entering the eye, but donot protect the eyes from dust like goggles can.

The preparation laboratory was a cluttered, dustyplace during the first visit, with accumulated dustthat could become airborne and be inhaled.Conditions were much improved during the secondvisit, due to improved housekeeping and thereplacement of dry cleaning methods (sweeping)with wet ones (wiping with damp cloths or sponges).As long as fossil preparation work is performed inthe hoods and current good housekeeping practicesare maintained, dust exposures in the preparationlaboratory are not expected to be problematic.

Local Exhaust VentilationTwo custom hoods in the preparation laboratory areused to contain dust and particulate generated duringthe removal of matrix from fossil bones. The hoodshave inadequate capacity to actually remove dustsgenerated during the cleaning of fossils, and thus aresuitable only for materials having negligible toxicity.Although the matrix contains a large proportion ofsilica, these processes most likely generate onlysmall amounts of the respirable silica particulate

thought to be a health hazard. By containing dustand projectiles, the hoods make housekeeping easierand control a potential eye hazard. It would bedesirable that all fossil preparation take place insidethe hoods, but the small size and number of thehoods currently prevents this. Good practice wouldbe to use the hoods when applying Butvar® tofossils (other than small repairs), since this will atleast partially control acetone vapors.

The hoods incorporate good basic design features,and function adequately as presently used to containlow toxicity particulate, but they do not fullyconform to ACGIH recommended design criteria.The major shortcoming of the hoods is the use ofaxial fans. Axial fans are generally not suitable foruse in configurations requiring air to be pulledthrough the ventilation system (e.g., hoods and ductwork).19 These fans are used when the objective ishigh volume flow rates at low pressure. Theinadequacy of the fans is the primary cause of thelow volumetric air flow rates in the hoods.Upgrading the hoods to meet volumetric flow criteriarecommended by ACGIH would require significantmodification and expense. A filter or other aircleaner, new fan (or fans), and ductwork would berequired, and the south hood would need installationof a floor and rear wall.

Future facilities should include hoods of sufficientdesign, flexibility, and size to accommodate the arrayof matrix removal operations conducted in thepreparation laboratory. One approach would be tostart with the portable hand grinding hoodconfiguration (VS-412, see Fig. 8) in the ACGIHVentilation Manual.19 The grilles in the floor of sucha hood should be large enough that the fossil beingcleaned does not unduly constrict air flow into thehood. A minimum duct velocity of 3500 fpm withan air flow of between 150 to 250 cfm of air persquare foot of bench area is recommended. Equal airflow distribution and a clean out drawer for largeparticulate and fossil fragments would be required.Back and side shields would be desirable to helpcontain projectiles and aid in the collection of dust.


The addition of a top to the hood shown in Figure 8would make a booth similar to those currently in use.An minimum air flow of 100 cfm per square foot ofbench area or a face velocity of 100 feet per minuteis recommended for the booth configuration. Anenclosed booth would be most effective atcontrolling dust and projectiles, but would be leastflexible for cleaning large fossils.

The enclosed hoods currently in use cannotaccommodate large fossils, such as the three footdiameter aggregate of horse pelvis, smaller fossils,and matrix observed during the site visits. Aportable chipping and grinding table configuration(VS-413, see Fig, 9) might be useful for such bulkyspecimens. A minimum duct velocity of 3500 fpmwith air flow of 150 cfm per square foot of hood faceshould be maintained. Provisions for equal air flowdistribution and a clean out drawer for largeparticulate and fossil fragments are shown in Figure9. The addition of a transparent cover to containstray projectiles may add significantly to thecomplexity and pressure drop across the system. Theintroduction of mandatory eye protection may bemore appropriate.

OtherPPE is the least desirable method for reduction ofworker exposures. It should be considered onlywhen engineering controls are not feasible or areinsufficient. Current HAFO policy is to have gloves,nuisance dust masks, ear plugs, and other PPEavailable to employees. This practice implies that arecognized health hazard exists in the workplace, butdoes not describe which hazards the equipment is toprotect employees from.

Furthermore, NIOSH investigators witnessedimproper use of PPE (respirator use by beardedemployee, inadequate insertion of earplugs). Thisindicates that employees are not trained in the properwearing and use of PPE, and that the PPE is notreducing exposures to the fullest extent possible.Use of PPE as a means of employee protection alsocarries risks, such as ear infections (dirty earplugs),allergic dermatitis (latex gloves) and heat stroke

(respirators in hot environments). Elements of asuccessful PPE program are specified in 29CFR1910Subpart I (PPE).39

A properly trained safety officer would haveexpertise and/or education in topics such as personalprotective equipment, and would be accountablewhen decisions such as the current PPE policy wereinstituted. Such a person could ensure correction ofthe deficiencies noted in this report and couldprovide HAFO employees with a workplace freefrom recognized hazards as specified in ExecutiveOrder 12196.33 The current staff are to becommended for their efforts to address previousNIOSH recommendations, but the lack of a trainedcollateral duty safety officer on site has hamperedtheir response.

CONCLUSIONS

Gamma Spectroscopy Normal levels of radionuclides from the 238U decayseries were found in the Horse Quarry soil. Elevatedconcentrations of radioactive elements were found inthe Horse Quarry fossils.

RadonRadon exposure in the collections room representsthe greatest radiological hazard at HAFO. Theelevated radon concentrations in the collections roomoriginate from the radioactive fossils kept in thestorage cabinets.

Ionizing RadiationExternal ionizing radiation exposures are at or nearbackground levels and pose little risk to health.Current good laboratory practices limit internalexposures to negligible levels.

Heat Stress


Some workers may be overexposed to hot conditionsduring typical summer afternoons. All outdoorworkers at HAFO are exposed to hot conditionssevere enough to warrant inclusion in a formal heatstress management program.

Respirable Crystalline SilicaThe high (20% - 25%) silica content of the soilmeans that silica exposures potentially exist. Undercurrent conditions and practices, actual silicaexposures are limited to very low concentrations.

Respirable and TotalAirborne DustAirborne dust exposures are low under mostconditions. Concentrations of dust can be highenough to cause nuisance effects during windyconditions, when loading/unloading the wheelbarrowwith soil, when sifting soil at the Horse Quarry, andwhen using the power tiller at the trail building site.

Local Exhaust VentilationThe custom hoods are adequate to physically containdust and projectiles, thus contributing tohousekeeping and safety. The axial fans in useprovide inadequate flow rates to capture andtransport dust out of the hoods and there are no dustcollectors to clean the exhausted air.

OtherThe current informal PPE program leads to improperusage of PPE, which in itself may lead to illness orinjury. A properly trained Safety Officer is neededat HAFO.

RECOMMENDATIONS

Radon1. Minimize the amount of fossils stored, disposeof scientifically unnecessary specimens;2. Apply one or more coats of Butvar® to fossilsafter cleaning;3. Store fossils in unoccupied, mechanicallyventilated rooms;4. Open one cabinet at a time, only open cabinetswhen placing or retrieving fossils, and minimize timespent in these areas;5. Label cabinets and rooms containing radioactivefossils. Each sign should include “Caution,Radioactive Material”, the trefoil radiation symbol,and “Radon Area”;6. Begin a quarterly passive radon monitoringprogram, including the collections room, preparationlaboratory, office areas, and inside the cabinets.Other buildings storing fossils should be included insuch a program, with monitors in fossil storage areasand nearby work areas;7. Future facilities should be designed with adesignated fossil storage room, with a dedicatedventilation system to exhaust the room or theindividual collections cabinets.

Ionizing Radiation1. Apply one or more coats of Butvar® to fossilsafter cleaning;2. Continue to require good laboratory practicessuch as handwashing after handling fossils, andprohibition of food, drink, tobacco, and storage ofpersonal items in fossil handling areas.

Heat StressA formal heat stress control program should beinstituted to reduce the risk of heat disorders inworkers. At a minimum, such a program shouldcontain the following:25,39

1. Provisions for assessing heat stress and heatalerts;


2. Medical questionnaire to screen for conditionsthat increase heat strain;3. Training for all field workers covering: thecauses, symptoms, predisposing factors, preventionand first aid for heat disorders. Training should alsoinclude methods used by HAFO to control heatexposures;4. Record keeping - who was trained, when, whatwas covered, how proficiency was tested;5. Methods HAFO will use to control excessiveexposures to heat, which may include provision ofwater, acclimatization schedules, work/rest regimens,radio contact and buddy systems and, heat alerts.

Local Exhaust VentilationContinue to use the existing hoods during fossilpreparation, Butvar® application, and carcassrendering. Future facilities should be designed tomeet peak seasonal demands on work space, withsufficient number and sizes of hoods. Local exhaustventilation systems should include:

1. Hood designed to accommodate varying sizes offossils and workers;2. Roughing filter, screen, or trap below the worksurface to capture small fossil fragments;3. Dust collection device (filter or cyclone)upstream from fan;4. Duct system and air handling unit designed andselected to provide sufficient capture velocity,transport velocity, and air flow volume.

Sufficient heated or cooled (depending on season)replacement air should be provided to approximatethe total air flow rate removed from the laboratory byexhaust ventilation systems. Laboratory areas whichshare a building with other uses (e.g, office space)should be under negative pressure relative to the non-laboratory areas.

OtherA PPE program should be created in accordance with29CFR1910 Subpart I (Personal ProtectiveEquipment), including:39

1. Hazard assessment;2. Documented rationale for choosing the selectedPPE;3. Employee training covering what PPE to use;when it should be used; donning, doffing, adjusting,and wearing; care, maintenance, and disposal; andlimitations of the PPE.

The Safety Officer should receive Collateral DutySafety Officer training, and other occupational healthand safety training as needed, as specified inExecutive Order 12196.33

REFERENCES1 King N [1996]. Letter of August 29, 1996, from

N. King, Hagerman Fossil Beds NationalMonument, National Park Service, U.S.Department of the Interior, to J.J. Cardarelli,Division of Surveillance, Hazard Evaluations,and Field Studies, National Institute forOccupational Safety and Health, Centers forDisease Control, U.S. Department of Health andHuman Services.

2 Cardarelli JJ, Jiggens TE [1997]. Letter of May28, 1997, from J.J. Cardarelli and T.E. Jiggens,Division of Surveillance, Hazard Evaluations,and Field Studies, National Institute forOccupational Safety and Health, Centers forDisease Control, U.S. Department of Health andHuman Services, to N. King, Hagerman FossilBeds National Monument, National ParkService, U.S. Department of the Interior.

3 Ahrenholz SA, Jiggens TE [1997]. Letter ofAugust 14, 1997, from S.H. Ahrenholz and T.E.Jiggens, Division of Surveillance, HazardEvaluations, and Field Studies, National Institutefor Occupational Safety and Health, Centers forDisease Control, U.S. Department of Health andHuman Services, to N. King, Hagerman FossilBeds National Monument, National ParkService, U.S. Department of the Interior.


4 National Park Service [1995]. Hagerman FossilBeds Official Map and Guide. Washington, DC:U.S. Department of the Interior, National ParkService.

5 National Weather Service [1998].HAGERMAN 2 SW, IDAHO (103932) Periodof Record Monthly Climate Summary. NationalWeather Service, Western Regional ClimateC e n t e r . W o r l d W i d e W e b[h t tp : / /www.wrcc . s a ge . d r i . edu /cgi -bin/cliRECtM.pl?idhage].

6 Smith KG and Bradley DA [1954]. TheGeological Survey of Wyoming Report ofInvestigations No. 4: Radioactive Fossil Bonesin Teton County, Wyoming. Laramie, WY: TheGeological Survey of Wyoming

7 Khandelwal GS and Singh JJ [1978].Radioactivity of Whale Vertebra Fossils in theChesapeake Bay Area. Health Physics35(8):411-413

8 Madson ME [1983]. Radioactive Turtle Shells.Rocks and Minerals 58:245-246

9 Storrs GW [1996]. Conversation on November4, 1997, between G.W. Storrs, Museum ofNatural History and Science, CincinnatiMuseum Center, and T.E. Jiggens, Division ofSurveillance, Hazard Evaluations, and FieldStudies, National Institute for OccupationalSafety and Health, Centers for Disease Control,U.S. Department of Health and Human Services.

10 NCRP [1978]. NCRP Report 57:Instrumentation and Monitoring Methods forRadiation Protection. Bethesda, MD: NationalCouncil on Radiation Protection andMeasurements. pp 120-121

11 Data Chem Laboratories Inc. [1995]. StandardOperating Procedure WR-EP-325 Determinationof Gamma Emitting Isotopes Rev. 2. Salt LakeCity, UT: Data Chem Laboratories Inc.

12 Data Chem Laboratories Inc. [1992]. StandardOperating Procedure WR-DC-200 SamplePreparation Procedures Rev. 1. Salt Lake City,UT: Data Chem Laboratories Inc.

13 Pylon Electronics Inc. [1993]. Pylon® ModelAB-5 Portable Radon Monitor InstructionManual A900024 Rev.5. Ottawa, ON, Canada:Pylon Electronics Inc.

14 ACGIH [1997]. 1996-1997 Threshold LimitValues for Chemical Substances and PhysicalAgents and Biological Exposure Indices.Cincinnati, OH: American Conference ofGovernment Hygienists.

15 NIOSH [1994]. Silica, crystalline, by XRD:Method 7500 In: Eller PM, ed. NIOSH Manualof Analytical Methods. 4th rev. ed. Cincinnati,OH: U.S. Department of Health and HumanServices, Public Health Service, Centers forDisease Control and Prevention, NationalInstitute for Occupational Safety and Health,DHHS (NIOSH) Publication 94-113.

16 NIOSH [1994]. Particulates not otherwiseregulated, respirable: Method 0600 In: Eller PM,ed. NIOSH Manual of Analytical Methods. 4threv. ed. Cincinnati, OH: U.S. Department ofHealth and Human Services, Public HealthService, Centers for Disease Control andPrevention, National Institute for OccupationalSafety and Health, DHHS (NIOSH) Publication94-113.

17 NIOSH [1994]. Particulates not otherwiseregulated, total: Method 0500 In: Eller PM, ed.NIOSH Manual of Analytical Methods. 4th rev.ed. Cincinnati, OH: U.S. Department of Healthand Human Services, Public Health Service,Centers for Disease Control and Prevention,National Institute for Occupational Safety andHealth, DHHS (NIOSH) Publication 94-113.

18 TSI Incorporated [1992]. Model 8355/8357VelociCalc® and Model 8360 VelociCalc®


Plus air velocity meters operation and servicemanual. St. Paul, MN: TSI Incorporated.

19 ACGIH [1988]. Industrial ventilation: A manualof recommended practice 30th ed. Cincinnati,OH: American Conference of GovernmentalIndustrial Hygienists.

20 NIOSH [1992]. Recommendations foroccupational safety and health: compendium ofpolicy document and statements. Cincinnati,OH: U.S. Department of Health and HumanServices, Public Health Service, Centers forDisease Control, National Institute forOccupational Safety and Health, DHHS(NIOSH) Publication No. 92-100.

21 Code of Federal Regulations [1989].29CFR1910.1000 Air Contaminants.Washington, DC: U.S. Government PrintingOffice, Office of the Federal Register.

22 ATSDR [1990]. Toxicological Profile for RadonTP-90-23. Atlanta, GA: U.S. Department ofHealth and Human Services, Public HealthService, Agency for Toxic Substances andDisease Registry

23 DOE [1994]. Science, Society and America’sNuclear Waste: Ionizing Radiation. Unit 2 1sted. Washington, DC: U.S. Department ofEnergyPublication DOE/RW-0362 SR.

24 Code of Federal Regulations [1991].10CFR20.1201 Occupational Dose Limits.Washington, DC: U.S. Government PrintingOffice, Office of the Federal Register.

25 ICRP [1983]. International Council onRadiation Protection Publication 36: ProtectionAgainst Radiation in the Teaching of Science.New York: Pergamon Press

26 Cohen R [1990]. Injuries Due to PhysicalHazards. In: LaDou J, ed. OccupationalMedicine. East Norwalk, CT: Appleton & Lange

27 NIOSH [1986]. NIOSH Criteria for aRecommended Standard: OccupationalExposure to Hot Environments rev. Cincinnati,OH: U.S. Department of Health and HumanServices, Public Health Service, Centers forDisease Control, National Institute forOccupational Safety and Health, DHHS(NIOSH) Publication No. 86-113

28 NIOSH [1975]. NIOSH Criteria for aRecommended Standard: OccupationalExposure to Crystalline Silica. Cincinnati, OH:U.S. Department of Health, Education, andWelfare, Public Health Service, Center forDisease Control, National Institute forOccupational Safety and Health, DHEW(NIOSH) Publication No. 75-120

29 ACGIH [1992]. Silica, Crystalline - Quartz. In:Documentation of the Threshold Limit Valuesand Biological Exposure Indices. 6th ed. Vol. II.Cincinnati, OH: American Conference ofIndustrial Hygienists, pp. 1377 - 1382

30 ACGIH [1992]. Particulates Not OtherwiseClassified (PNOC). In: Documentation of theThreshold Limit Values and BiologicalExposure Indices. 6th ed. Vol. II. Cincinnati,OH: American Conference of IndustrialHygienists, pp. 1166 - 1167

31 NCRP [1993]. NCRP Report 118:RadiationProtection in the Mineral Extraction Industry.Bethesda, MD: National Council on RadiationProtection and Measurements. p. 14

32 Dixon DW [1983]. Radiation Hazards toCollectors of Geological Specimens ContainingRadioactivity. National Radiological ProtectionBoard Technical Report NRPB-R131

33 Code of Federal Regulations [1980].29CFR1960 Basic Program Elements forFederal Employee OSH Programs and RelatedMatters. Washington, D.C.: U.S. GovernmentPrinting Office, Office of the Federal Register.


34 Lambert MP [1994]. Ionising RadiationAssociated with the Mineral Collection of theNational Museum of Wales. Collections Forum10(2):65-80

35 Lambert MP [1991]. Hazardous GeologicalSpecimens and their Control. In: Child RE, ed.Conservation of Geological Collections.London, UK: Archetype Publications

36 Wilson ML [1993]. Radioactive Specimens inMuseum Collections. Carnegie Museum ofNatural History Internal Report. Pittsburgh, PA.

37 Faller EW and Price KW [1995]. RadonMeasurement in Mineral Collection StorageCases. Yale University Peabody MuseumInternal Report. New Haven, CT.

38 Mast, G [1995]. Colorado School of MinesProcedures for Management of RadioactiveMineral Specimens. Society of MineralMuseum Professionals Newsletter, Fall 1995.

39 Code of Federal Regulations [1994].29CFR1910 SubPart I Personal ProtectiveEquipment. Washington, DC: U.S. GovernmentPrinting Office, Office of the Federal Register.

40 Mutchler JE [1991]. Heat Stress: Its Effects,Measurement, and Control. In: Clayton GD andClayton FE, eds. Patty’s Industrial Hygiene andToxicology, 4th ed., Vol. 1, Part A. New York:John Wiley and Sons, Inc.


Appendix Uranium Decay Series, 238U (4n+2)†

Nuclide Half-Life

Major Radiation Energies (MeV) and Intensities‡

"""" $$$$ ((((

MeV % MeV % MeV %23892

U

9999

4.468 x 109 y 4.154.20

22.976.8

0.0496 0.07

23490

Th9999

24.1 d 0.0760.0950.0960.1886

2.76.218.672.5

0.06330.09240.09280.1128

3.82.72.70.24

234m91

Pa9999

1.17 m 2.28 98.6 0.7661.001

0.2070.59

99.87%23491

Pa9999

0.13%23491

Pa IT

9999

6.7 h 22 $sE Avg = 0.224Emax = 1.26

0.1320.5700.8830.9260.946

19.710.711.810.912.0

23492

U9999

244,500 y 4.724.77

27.472.3

0.0530.121

0.120.04

23090

Th9999

7.7 x 104 y 4.6214.688

23.476.2

0.06770.1420.144

0.370.070.045

22688

Ra9999

1600 ± 7 y 4.604.78

5.5594.4

0.186 3.28

22286

Rn9999

3.823 d 5.49 99.9 0.510 0.078

21884

Po9999

3.05 m 6.00 -100 0.33 0.02 0.837 0.0011

99.98%21482

Pb9999

0.02%9999

26.8 m 0.670.731.03

48.042.56.3

0.24190.2950.3520.786

7.519.237.11.1

21885

At9999

2 s 6.666.7

6.757

6.489.93.6

0.053 6.6

21483

Bi9999

19.9 m 5.455.51

0.0120.008

1.421.5051.543.27

8.317.617.917.7

0.6091.121.7652.204

46.115.015.95.0

Appendix (continued) Uranium Decay Series, 238U (4n+2)†

Nuclide Half-Life

Major Radiation Energies (MeV) and Intensities‡

"""" $$$$ ((((

MeV % MeV % MeV %

Page 26 Health Hazard Evaluation Report No. 96-0264-2713

99.979%

21484

Po9999

9999

9999

0.021%9999

164 µs 7.687 100 0.7997 0.010

21081

Tl9999

9999

9999

9999

9999

1.3 m 1.321.872.34

25.056.019.0

0.29180.79970.8601.1101.211.3101.4102.0102.090

79.199.06.96.917.021.04.96.94.9

21082

Pb9999

22.3 y 3.72 0.000002 0.0160.063

80.020.0

0.465 4.0

21083

Bi9999

5.01 d 4.654.69

0.000070.00005

1.161 -100

-100%21084

Po9999

0.00013%9999

138.378 d 5.305 100 0.802 0.0011

20681

Tl9999

4.20 m 1.571 100 0.803 0.0055

20682

Pb Stable

y = Year " = alpha decayd = Day $ = beta decayh = hour ( = gamma decaym = minute IT = Internal transitions = second MeV = million electron volts:s = microsecond (10-6 s)

† This expression describes the mass number of any member in this series, where n is an integer. For example: 206Pb(4n+2)...4(51) + 2 = 206.

‡ Intensities refer to percentage of disintegrations of the nuclide itself, not to original parent of series. Gamma %sin terms of observable emissions, not transitions.


ABBREVIATIONS AND TERMS

acclimatization(see heat acclimatization.)

ACGIHAmerican Conference of Governmental Industrial Hygienists

alpha particleForm of radiation composed of two protons and two neutrons. Stopped by a sheet of paper, won’t penetrateskin.

Becquerel(Bq) Unit of radioactivity equal to one nuclear transformation per second.

beta particleForm of radiation identical to an electron. Stopped by a thin sheet of aluminum.

carcinogenAgent that causes cancer.

CFMCubic feet per minute

CFRCode of Federal Regulations

Curie Special unit of radioactivity equal to 3.7 x 1010 disintegrations per second.dry bulb temperature

Air temperature as it is usually taken with a thermometer.EPA

Environmental Protection AgencyFPM

Feet per minutegamma ray

Form of radiation composed of massless photons. Stopped by thick sheets of lead or concrete.globe temperature

Temperature measured by a thermometer placed in the center of a blackened, hollow, thin copper globe. Ameasure of radiant (infrared) heat.

HAFOHagerman Fossil Beds National Monument

heat acclimatizationPhysiologic changes which reduce the heat strain (of the body) caused by heat stress (of the environment).Acclimatization occurs in response to a succession of days of exposure to environmental heat stress.

heat exhaustionHeat disorder characterized by weakness, fatigue, confusion, nausea, and continued sweating (pale, clammyskin).

heat strainNet physiological load due to heat stress, level of heat acclimatization, degree of hydration, underlying medicalconditions, and other factors.


heat stressNet heat load on the body due to metabolic (internal) heat, air temperature, wind speed, humidity, radiant heat(sunlight) and clothing.

heat strokeFailure of the body’s temperature regulation mechanism, resulting in a dangerous rise in body temperature(above 106 °F). Symptoms of this potentially fatal medical emergency include lack of sweating (hot, dry skin),nausea, dizziness, and unconsciousness.

IARCInternational Agency for Research on Cancer

ICRPInternational Commission on Radiological Protection

ionizing radiationRadiation with enough energy to remove electrons from (ionize) matter.

LODLimit of detection

LOQLimit of quantitation

MDCMinimum detectable concentration

::::mA micrometer is one millionth of a meter. There are about 3940 :m in an inch.

mREMA milliREM equals one one-thousandth of a REM.

Q MCMinimum quantifiable concentration

NCRPNational Council on Radiation Protection and Measurements

NIOSHNational Institute for Occupational Safety and Health, part of the Centers for Disease Control and Preventionin the U.S. Department of Health and Human Services

NPSNational Park Service

NRCNuclear Regulatory Commission

NTPNational Toxicology Program

NVLAPNational Voluntary Laboratory Accreditation Program

OSHAOccupational Safety and Health Administration, part of the U.S. Department of Labor

pCiA pico-curie is equal to one trillionth of a curie (1 X 10-12 Ci).

PELPermissible Exposure Limit (OSHA)

photonMassless form of radiant energy.


pneumoconiosisScarring of lungs caused by long term inhalation of dusts.

PNOCParticulates Not Otherwise Classified (ACGIH). Dust particles that do not scar the lungs, change thearchitecture of the air spaces in the lungs, nor cause any irreversible tissue reaction.

PNOR Particulates Not Otherwise Regulated (NIOSH, OSHA). Dust particles, both organic and inorganic, notgoverned by a specific OSHA regulation.

PPEPersonal protective equipment

PVCPolyvinyl chloride

radiationA way that energy is release from matter and travels through space.

radioisotopeRadioactive form of an element.

radonElement 86 (symbol Rn), a colorless, odorless, radioactive noble gas.

radon daughterAlso radon progeny. Short-lived radioisotopes formed by the radioactive decay of radon.

RELRecommended Exposure Limit (NIOSH)

REMRoentgen Equivalent Man is a unit of absorbed radiation dose that takes into account different weightingfactors for different types of radiation.

SvSeivert is a unit of absorbed radiation dose that takes into account different weighting factors for different typesof radiation. 1 Sv = 100 REM.

TLDThermoluminescent detector

TLV®Threshold Limit Value (ACGIH)

TWATime-weighted average

uranium daughterRadioactive elements formed by the radioactive decay of uranium. (See Appendix)

WBGTWet-Bulb Globe Temperature is a heat stress index that takes into account the dry bulb, wet bulb, and globetemperatures.

wet bulb temperatureThe lowest temperature to which ambient air can be cooled by (natural) evaporation of water. Measured witha thermometer placed in a wetted sock-like wick.


Table 1HETA 96-0264

Hagerman Fossil Beds National Monument

Heat Stress TLV®’s (°F WBGT)A

Work/Rest RegimenLight WorkB

(150-250 kcal/hr)Moderate WorkB

(250-450 kcal/hr)Heavy WorkB

(>450 kcal/hr)

Continuous Work < 86.0 < 80.0 < 77.0

15 min. rest each hr 86.0 - 87.0 80.0 - 82.5 77.0 - 79.0

30 min. rest each hr 87.0 - 89.0 82.5 - 85.0 79.0 - 82.5

45 min. rest each hr 89.0 - 89.5 85.0 - 88.0 82.5 - 86.0

A For each wet-bulb globe temperature (WBGT) the TLV® indicates a work/rest regimen “under which it isbelieved that nearly all heat acclimatized, adequately hydrated, unmedicated, healthy workers wearing light-weightsummer clothing may be repeatedly exposed without adverse health effects.” (Ref. 14)

B Brushing and troweling of loose soil from fossil bones is an example of light work. Using a hammer and chiselto remove hard matrix from a fossil bone would constitute medium work. An example of heavy work is removingoverburden with a pickaxe.


Table 2HETA 96-0264-2710


Passive Radon Monitoring Results

Monitor # Type LocationA Results (pCi/L)B

Administration Building

1 Landauer Collections Room, Inside Cabinet 1 380

2 Landauer Collections Room, Inside Cabinet 7 500

3 Landauer Collections Room, Desk 8.1

4 Landauer Collections Room, Back Wall 8.2

5 Alpha-Spectra Preparation Room, Inside Cabinet 128

6 Alpha-Spectra Prep. Rm. near Door to Collections Room 1.9

7 Landauer Preparation Room, near Door to Hallway 1.9

8 Landauer Reception Area 1.8

9 Landauer Library 0.4

10 Landauer Office 2.5

Visitor Center

11 Alpha-Spectra Office 2.5

12 Alpha-Spectra Audio/Video Room 1.6

13 Alpha-Spectra Auditorium < MDCC

14 Alpha-Spectra Exhibit Area < MDCC

A See Figures 1 and 2 for diagrams of monitoring locations.B Results presented as picoCuries of Radon activity / liter of air.C <MDC means result was less than the Minimum Detectable Concentration (0.4 pCi/L).


Table 3HETA 96-0264-2710


Silica Content of Soil Samples

Sample Site % Silica by Mass

Horse Quarry - North end of floor 25%

Horse Quarry - South end of floor 23%

Horse Quarry - North end of back wall (fossil-bearing layer) 21%

Horse Quarry - salvage pile 24%

Horse Quarry - matrix around fossil boneA 20%

Snake River Public Access Site - Hagerman side of river 16%

A Sample was gathered at the fossil preparation lab, but was originally excavated from the Horse Quarry.


Table 4HETA 96-0264-2710


Cyclone Results

Date Work Locations Work Activities

SamplePeriod

(minutes)

Respirable Concentration(mg/m3)

Particulate Silica

7/24/97 Horse Quarry digging with brush, trowel; surveying 519 0.08 < MDCA

7/24/97 Horse Quarry digging with brush, trowel; surveying; earthmoving (shovel &wheelbarrow)

525 0.03 < MDCA



414 0.06 < MDCA



525 0.09 0.04

7/23/97 Horse Quarry digging with brush, trowel, hammer & chisel; surveying 420 0.06 < MDCA

7/24/97 Field trailbuilding with shovel, rake, hoe 481 0.22 traceB

7/24/97 Horse Quarry digging with brush, trowel, hammer & chisel; surveying 510 0.02 < MDCA

7/24/97 Horse Quarry digging with hammer & chisel, pickax & shovel; earthmoving (shovel& wheelbarrow)

493 0.04 < MDCA

A < MDC means that sample was less than the Minimum Detectable Concentration (approximately 0.012 mg/m3).B Trace means that sample was greater than the MDC, but less than the minimum quantifiable concentration (0.037 mg/m3).


Table 5HETA 96-0264-2710


Total Airborne Particulate

Date Work Location(s) Work Activities

SamplePeriod

(Minutes)Conc.

(mg/m3) Remarks

5/14/97 Visitor Center handling modern bones & fossils; desk work 453 0.05

5/14/97 Visitor CenterAdmin. Bldg.Field

moving fossils; desk work; capturing crawfish 500 0.52

5/14/97 Field hiking, collecting water samples 500 0.26

5/14/97 Prep Lab cleaning fossils w/dental picks, toothbrushes 421 0.20 In East hood

5/15/97 Prep Lab cleaning fossils w/dental picks, toothbrushes 480 0.10 In East hood

5/15/97 Prep Lab cleaning fossils w/dental picks, toothbrushes 512 0.10 Area sample, above East hood

5/15/97 Prep Lab cleaning fossils w/dental picks, toothbrushes, hammer &chisel

469 0.68 Corner table, no hood

5/15/97 Prep Lab cleaning fossils w/dental picks, toothbrushes, hammer &chisel

512 0.24 Area sample, above corner table

7/23/97 Horse Quarry digging with brush, trowel, hammer & chisel; surveying 420 0.49

7/23/97 Horse Quarry digging with brush, trowel; surveying 420 0.35

7/23/97 Horse Quarry digging with brush, trowel; surveying 428 0.45

7/23/97 Horse Quarry digging with brush, trowel; surveying; earthmoving(shovel & wheelbarrow)

414 0.44

Total Airborne Particulate


7/24/97 Field trailbuilding with shovel, rake, hoe 480 187.90 Invalid sample (Loose material insidefilter cassette)

7/24/97 Horse Quarry digging with brush, trowel; surveying; earthmoving(shovel & wheelbarrow)

528 0.54


Table 6HETA 96-0264-2710


Local Exhaust System Ventilation MeasurementsA

Hood Front PanelConfiguration

Face Velocity (fpm)B

Left RightVolumetric Flow

Rate (cfm)CVolumetric Flow / Bench

Area (cfm/ft2)D

East Arm holes 183 196 134E 25

None 90F

South Arm holes 238 193 262G 44

Slot at top 220 355G 60

Rec.H 100 150-250

A Hood lid closed, no worker in place.B Linear velocity in feet per minute of air into hood face.C Volumetric flow rate in cubic feet per minute of air exhausted from hood.D Volumetric flow rate (in cubic feet per minute) per square foot of hood floor area.E Measured at hood discharge.F Not measured; hood is not used without front panel.G Measured at fan discharge; equivalent to hood discharge since system has no ductwork.H Recommended ranges according to Reference 19.

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For Information on OtherOccupational Safety and Health Concerns

Call NIOSH at:1–800–35–NIOSH (356–4676)

or visit the NIOSH Homepage at:http://www.cdc.gov/niosh/homepage.html

!!!!Delivering on the Nation’s promise:

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HHE Report No. HETA 96-0264-2713, Hagerman Fossil Beds ......Hagerman (elev. 2960 ft), on the east...

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Transcript of HHE Report No. HETA 96-0264-2713, Hagerman Fossil Beds ......Hagerman (elev. 2960 ft), on the east...