HOSPITAL WASTE

MANAGEMENT

 

Presented ByDr.Sayqa AzizPG StudentDeptt.of Prosthodontics.

Introduction.Definition.Rules and lawsColor codingWHO ClassificationPurpose of management.Wastes in clinicsHandling and storage.On-site treatment.Treatment off-site.Contingency planningPublic relations.Summary and Conclusion.References.

CONTENTS

DefinitionAccording to Bio-Medical Waste (Management and Handling) Rules, 1998 of India,

Bio-medical waste - “means any waste, which is

generated during the diagnosis, treatment or

immunization of human beings or animals or in research

activities pertaining thereto or in the production or

testing of biologicals.”

This also includes 10 categories as mentioned in

schedule I, categories of Bio-Medical Waste in India

As per the law it has two schedules namely:

Schedule-1:Cateogaries of Bio-medical waste.

Schedule-2:Color coding and type of containers for the waste.

CATEGORIES OF BIO- MEDICAL WASTE IN INDIA AS PER SCHEDULE-1

1. Category No.1 Human Anatomical waste

2. Category No.2 Animal Waste

3. Category No.3 Microbiology and Biotechnology Waste

4. Category No.4 Waste sharps

5. Category No.5 Discarded medicines and Cytotoxic drugs

6. Category No.6 Solid waste Items contaminated with blood, and fluids

7. Category No.7 Solid waste i.e wastes generated from disposable items

such as tubings, catheters, intravenous sets etc

8. Category No.8 Liquid waste i.e waste generated from laboratory and

washing, cleaning, housekeeping and disinfecting activities)

9. Category No.9 Incineration ash

10. Category No.10 chemicals used in disinfection , as insecticides etc

Color coding and type of container for disposal of biomedical wastes-Schedule 2

Color coding

Type of Bag Waste Treatment option as per Schedule- 2

Yellow Plastic Bag Cat. 1, 2, 3, & 6

Incineration/deep burial

Red Disinfected container/ plastic bag.

Cat. 3, 6 & 7 Autoclaving/ microwaving/Chemical Treatment.

Blue/White translucent

Plastic bag/ punctureproof container

Cat. 4&7 Autoclaving/ microwaving /chemical treatment and destruction/ shredding.

Black Plastic bag Cat. 5,9 and Cat. 10 (solid)

Disposal in secured landfill

COLOR CODED BINS

In exercise of the powers conferred by section 6, 8 and 25 of the Environment (protection) act, 1986 the central government,om 2nd June notified the rules for the management and handling of bio-medical waste. These rules are called the Bio-Medical Waste (Management and Handling) (Second Amendment) Rules, 2000.

These rules apply to all persons who generate, collect, receive, store, transport, treat, dispose, or handle bio medical waste in any form.

The Bio-medical Waste (Management rules,2000.alnd Handling) (Second Amendment) R

W.H.O. CLASSIFICATION

•All waste from dental offices can be divided into two basic categories:  Regulated and Non-regulated.

• Regulated waste, according to OSHA definition, is liquid or semi liquid blood or other potentially infectious materials and items that would release blood or other potentially infectious materials if compressed.

•Regulated waste must be placed into appropriately designed containers, usually red biohazard bags or sharps boxes. 

•Ideally, segregation should occur as close as possible to the point of origin. 

•The person disposing of an item should know best which type of container to select. 

Other potentially infectious materials are body fluids that are visibly contaminated by blood.

Infectious/hazardous waste is also included under Regulated Waste because certain segregation, storage, and disposal procedures must be followed.

While this waste is in the dental office and a potential hazard to the employees, it is covered by OSHA regulations. Infectious waste is a small subset (estimated to be 3% in hospitals and 1-2% in dental offices) of the total waste to be discarded.  Infectious waste is the part of medical/dental waste   For e.g., contaminated sharps, teeth, pathological waste and blood soaked items. Also known as hazardous waste.

Non-Hazardous waste

Disposable paper towels, paper mixing pads, disposable covers of operating surfaces.

Should be discarded in separate covered containers made of durable material such as plastic or metal receptacles.

For ease in handling, the receptacles should be lined with plastic bags.

Where are these Bio-medical waste generated???

• Government hospitals• Nursing homes• Private hospitals• Physician's office/clinics• Dentist's office/clinics• Dispensaries• Primary health centers• Medical research and training

establishments

WHY WE NEED MANAGEMENT??

The primary purpose is :

• To reduce the likelihood of infection to staff and the general public contacting a disease or injury from biomedical waste.

• To reduce any injury from the sharps.• To reduce exposure to various radioactive or

chemical wastes. • To educate the public, and the concerned authorities

about the real and perceived health risk associated with the management of biomedical waste.

INJURY

AWARENESS

Wastes in DENTAL CLINICS:

Chemicals used like etchants and monomers, X-ray processing solutions&cleaning solutions.

Solid wastes like Plaster of paris,Dental stone,Die stone etc Impressions drenched in saliva and/or blood. Contaminated needles and scalpel blades. Diamond points,burs ,instruments,broken glassware. Base metal debris and mercury from amalgam restorations. Dental waxes. Cotton Liquid waste containing toxic substances flushed down a

drain or sink to sewers.. 

Gypsum products

Dental impressions

Dental waxes

Chemical wastes like MONOMER,ETCHANTS etc

Sharps

Others

REGULATIONREGULATIONSS

AFFECTING AFFECTING DENTALDENTAL

PRACTICEPRACTICE

Environmental Protection Agency (EPA)

Occupational Safety & Health Administration (OSHA)

Centers for Disease Control and Prevention (CDC).

 

Basic Principals of Bio-medical Waste Management

• Waste Minimisation • Waste treatment on-site • Waste transportation • Waste treatment off-site • Final Disposal To achieve this Cradle to Grave Aspect should be

followed

 

Cradle to Grave Aspect• Segregation (Separation)• Identification• Collection• Storage• Transport• Measurement• Treatment• Disposal• Training, Health and safety records of the workers

•The majority of soiled items are not regulated waste.  For

example, used gloves, masks, and gowns are not considered

regulated dental waste and thus can be added to the regular

trash. 

•The same is true for environmental barriers (e.g., plastic bags or

sheets and aluminum foil) used to cover equipment during

treatment.

HANDLING AND STORAGE

     Safe handling of regulated waste is essential.

Written procedures will help in this process.  Involved personnel must be informed of the possible health hazards present and trained in appropriate handling, storage, and disposal methods.

     Stored regulated waste must be placed into labeled or color-coded bags or containers. Usually such items are red and have biohazard symbols attached.

 

                      

        Bio-Hazard Symbol  

Cytotoxic Hazard Symbol

  The receptacles should be covered with properly fitted lid that can be opened with a foot pedal. Keeping the lid closed prevents air movement, as well as the spreading of contaminants.

Waste receptacles should be lined with sturdy plastic bags that can be removed without touching the interior of the liner. Double-bagging of liners may also be recommended to eliminate accidental exposure should one of the bags rip or tear.

Ideally, regulated waste should be stored as soon as possible with a minimum of transport.

Maintaining bag and container integrity is vital and overfilling must be avoided. 

Regulated waste must be stored in a properly ventilated, secured area that cannot be readily seen by patients. 

Generally, waste should not be stored for more than 30 days. 

Waste containers must be designed to prevent the development of offensive odors.

Waste is discarded in a leak - resistant package that is impervious to moisture.

The bag is sealed to prevent leakage during transportation to the final dumpsite.

If hazardous waste is shipped, store the containers in an exclusive refrigerator to maintain the integrity of the contents and to control odor until the pick-up date.

  Sink traps and evacuation lines should be thoroughly rinsed at least daily. 

Passage of an effective, environmentally compatible disinfectant or evacuation cleaner (low sudzing) through the system would help.  A final water rinse should follow.

Dental Unit Waterlines, Biofilm, and Water Quality

• General Recommendations 1.Use water that meets EPA regulatory standards for drinking water

(i.e., <500 CFU/mL of heterotrophic water bacteria) for routine dental treatment output water

2.Consult with the dental unit manufacturer for appropriate methods and equipment to maintain the recommended quality of dental water

3. Follow recommendations for monitoring water quality provided by the manufacturer of the unit or waterline treatment product

4. Discharge water and air for a minimum of 20--30 seconds after each patient, from any device connected to the dental water system that enters the patient's mouth (e.g., handpieces, ultrasonic scalers, and air/water syringes)

5. Consult with the dental unit manufacturer on the need for periodic maintenance.

OSHA HOUSEKEEPING REQUIREMENTSThe housekeeping section of the OSHA Bloodborne Pathogens Standard includes provisions for handling :

Contaminated sharps and instruments

Spills

Broken contaminated glassware

Regulated waste.

Sharps

The term sharps refers to any sharp or pointed object that can penetrate the skin or oral mucosa. In dentistry, the most common types of sharps are:

Needles

Scalpel blades and disposable scalpels

Exposed ends of dental arch wires

Broken glass

Burs and endodontic instruments

   

SHARPS

Wires Burs

Burs Endo.files

LOCAL ANAESTHESIA

BOTTLES

The OSHA Bloodborne Pathogens Standard contains specific guidelines concerning sharps containers: 

Sharps containers must be closeable, leak-proof, puncture-resistant items labeled with a biohazard symbol or color-coded red to identify it as a hazard.

They should be capable of maintaining their impermeability during storage, transport, treatment, and disposal.  This will help prevent occupational exposure to container contents. 

Sharps should be quickly placed into sharps containers after use.  They must be placed into acceptable containers as close as practically possible to their point of use.

Sharp items should be considered as potentially infectious materials and thus handled with extraordinary care to prevent accidental injuries.

Contaminated sharps are never touched with bare hands, but by wearing appropriate gloves or by using transfer forceps.

Sharp containers should be replaced routinely before they are over filled.

Discarding used needle.

Of special concern among contaminated sharps are used needles.  The CDC estimates that healthcare workers sustain nearly 600,000 percutaneous injuries annually involving contaminated sharps. In response to a continuing concern of exposure and the development of technological advances that increase employee protection, the US Congress passed the Needlestick Safety and Prevention Act in 2000. Enforcement of the new provisions in the standard began on July 17, 2001.

Proper handling of sharps is essential because personal protective barriers, such as gloves, will not prevent all needlestick accidents.  To minimize the potential for exposures, needles should not be recapped, bent, or broken by hand. 

Instead a “hands-free” or a “one-hand” technique must be used.

The hands free technique involves the use of a cap holder, which allows the slipping of the needle into it without touching it.

In a one-hand technique, the needle guard is placed on a tray, and the used needle is wiggled into the cover. Once the end of the needle is covered, it may be safely brought in to position.

Needle disposal unit.

The recapped needle is then discarded in the nearest sharps container.

Recommendations Procedures for Sterilization of Sharps Containers in Steam Autoclaves

1. 1.     Use only containers approved for the collection and storage of sharps and

which are autoclavable.

2. 2.     Biologically monitor the autoclave used on a regular basis (e.g., weekly).

3. 3.     Consider the following procedural recommendations:

4. a.      Fill containers no more than ¾ full

5. b.     Leave container vents open

6. c.     Place the containers in an upright position in the autoclave chamber

7. d.     Process containers for 60 minutes (e.g., two regular length cycles, unless a

single longer cycle can be used)

8. e.      Remove containers after processing and allow them to cool

9. f.       Carefully close container vents

10. g.     Label and dispose of containers according to local governmental regulations

Infectious material spills.

Spilled or dropped potentially infectious materials such as gauze saturated with blood, must be cleaned up immediately.

Utility gloves and protective barrier clothing are worn.

The area of spillage is wetted with a suitable disinfectant such as 1:10 sodium hypochlorite solution.

Use a large pad of paper towels so that the gloves do not contact the liquid. Discard the towels after use.

Apply the disinfectant again. Leave the area wet for 10 mins and then dry it with fresh paper towels.

Remove gloves carefully to avoid touching the contaminated outside, and wash hands immediately. Wash, dry and autoclave gloves after use if required.

Broken glass.

If contaminated broken glass or something sharp drops, do not pick it up with the hands. Instead use tongs, forceps, or a dustpan and brush.

Discard, clean and disinfect, or sterilize items used for this purpose.

Broken glass or dropped sharps are discarded in the sharps container.

After the sharp material has been removed, disinfect the area as after a spill.

Discarding local anesthetic cartridges.

If the glass anesthetic cartridge is broken, pick up the broken glass as previously described and discard the broken glass with the sharps.

If the glass anesthetic cartridge is not broken and not visibly contaminated with blood, discard it with other nonhazardous waste.

If the glass anesthetic cartridge is visibly contaminated with blood, discard it with regulated waste.

PATIENT’S IMPRESSIONS

Medical lab specimens, such as biopsy samples of suspected oral cancerous lesions, to be transported outside of the office for evaluation must be placed in leakproof bags and labeled appropriately.

Dental impressions must also be placed in leakproof bags and labeled appropriately.

Contaminated laundry

The dental personnel should either use disposable uniforms or make arrangements for laundering or professional cleaning of protective clothing.

Clothing dispatched to a commercial laundry should be packed in red laundry bags, clearly labeled with a biohazard symbol.

Contaminated laundry

The dental personnel should either use disposable uniforms or make arrangements for laundering or professional cleaning of protective clothing.

Clothing dispatched to a commercial laundry should be packed in red laundry bags, clearly labeled with a biohazard symbol.

Amalgam disposal.

Three aspects of amalgam waste may be considered.

Amalgam scrap.

Other waste contaminated with amalgam.

Amalgam in waste water.

 Amalgam scrap: Is stored under radiographic fixer solution in a covered container. Should be recovered and recycled whenever possible. It is considered as hazardous waste with chances of mercury leaching out of amalgam scrap. Hence they should be disposed off as required for that of a regulated waste and as per local regulations. It should not be disposed with waste that would be eventually incinerated since amalgam decomposes on heating.

Management of mercury spills.Never use a vacuum cleaner, broom or paintbrush or household cleaning products like ammonia or chlorine.

Never allow mercury to go down the drain.

In case the shoes are contaminated with the spilt mercury, the person is asked not to walk around or leave the spill area until the contaminants are removed.

Sprinkling of sulfur powder on mercury spills has shown to be ineffective and inadequate to control the problem, because of the slow reaction.

Mercury spills are cleaned up properly by using trap bottle, tapes, or fresh mixes of amalgam to pick up droplets, or use commercial clean up kits.

If the floor carpeting in the operatory gets contaminated with mercury, removal of the carpeting may be the only effective way to ensure decontamination. Chemical decontamination of the carpeting may be ineffective since mercury might seep through the carpet and remain inaccessible to the decontaminant.

Managing silver and lead waste.Silver in used radiographic fixer solutionsUse of an in-office silver recovery unit to remover silver from used fixer solutions and recycle the used cartridge.Send used fixer solution to a silver reclaiming facility.Send it to a medical radiology lab or a commercial photographic processing lab, on agreement.

Lead foil in intraoral radiograph film packets.Should be collected and recycled through a licensed facility.The same would apply to lead aprons and lead collars.

ON-SITE TREATMENT

•Many areas allow in-house treatment of regulated medical/dental waste.  An easy and effective procedure is sterilization by moist heat (autoclaving). 

• Dry heat ovens should not be used.  Of course, the performance of the sterilizer must be biologically monitored regularly.

•Where allowed, sharps containers can be sterilized in-house.  The open containers should be placed into the sterilizer in an upright position.

AUTOCLAVE

AUTOCLAVE

• It’s a low heat thermal process using steam to come in contact with the surfaces or the instruments.

• Temperature-121 C• Time-30-60 Minutes• Pressure-30psi• USE:Reusable instruments mostly

In-house treated regulated waste items can then be added to the non-regulated office waste.  These items should be labeled as “treated” or with other information as required by local laws.

Pathologic waste is considered to be potentially infectious and must be regulated. 

Teeth without amalgam restorations and other tissues can be placed directly into a biohazard bag or a sharps container.  Where allowed, the waste can then be sterilized. 

Teeth with amalgams could release mercury vapor during sterilization, thus, they should be neutralized through disinfection (ideally, immersion for 30 minutes in a fresh solution of a tuberculocidal disinfectant held within a sealed container). 

Treated teeth can then be rinsed with water and are ready for disposal.

Items heavily soiled (even saturated) with blood/saliva can

be placed into a sharps container.  However, it may be easier

to store them in small biohazard bags until treated.

  Used anesthetic carpules should also be placed into sharps

containers.

. 

Different methods of waste treatment{OFF-SITE}

• TREATMENT OFF-SITE

• Some areas may require regulated waste be

removed, neutralized, and disposed of by a

commercial waste hauling service,

regulated by the local government

Incinerators• Comes from a Greek word ..Meaning “BURN

TO ASHES”• No universal incinerator exists• It must be specifically selected, designed , and

built to meet the needs of the individual Hospital• Design depends upon type of waste , calorific

value ,quantities and volume of waste

TYPES OF INCINERATORS Three basic kinds of incineration technology

are of interest for treating health-care waste:

(a) Double-chamber Pyrolytic incinerators which may be especially designed to burn infectious health-care waste;

(b) Single-chamber furnaces with static grate,

which should be used only if pyrolytic

incinerators are not affordable

Rotary kiln: A Rotary kiln is a pyro processing device used to raisematerials to a high temperature in a continuous process.

Waste types to be incinerated are:1)Blood and Blood products2)Any waste which had a contact with

saliva/blood –cotton swabs3)Specimens like impressions.

Waste types not to be incinerated are : (a) pressurized gas containers; (b) large amount of reactive chemical

wastes; (c) silver salts and photographic or

radiographic wastes;

(d) Halogenated plastics such as PVC; (e) waste with high mercury or cadmium

content, such as broken thermometers, used batteries, and lead-lined wooden panels; and

(f) sealed ampules or ampules containing heavy metals .

Final disposal

Chemical decontamination can be carried out in a special decontamination tank with drainage facilities and also a chain and pulley block for loading/introducing operations of the large buckets in which the waste are placed for decontamination.

Disposal of incinerator ash

The ash generated by the incinerator can be disposed of in an Engineered Band fill which is chemically treated to prevent seepage of metal into the earth. The ash generated by incineration will contain mercury, arsenic, lead and cadmium all heavy metals harmful to the human body.

Chemicaldisinfection

• Chemical disinfection is defined as process by which most of the pathogenic organisms from any animal surface or material is killed

• Eg.Infectious wastes-infected sharps• - Contaminated instruments• -Contaminated Burs• -Patient’s impressions• However, solid wastes including

microbiological cultures, sharps etc. may also be disinfected chemically with certain limitations.

GDH(2.5%)

Formaldehyde(10%)

Glutaraldehyde(2.5%)

Chlorine dioxide(0.1-1%)

Sodium hypochlorite

LAND DISPOSAL

MUNICIPAL DISPOSAL SITES: If a municipality or any authority genuinely

lacks the means to treat waste disposal, the use of a land fill has to be regarded acceptable disposal route.

There are three types • Open dumps • Sanitary landfills• Deep Burial.

Open dumps• The waste is disposed off

somewhere in the open areas of non-civilised or minimally populated areas so that there is no or less conatct of the public.Health-care should not be deposited on or around open dumps.

• The risk of either people or animals coming into contact with infectious pathogens is obvious.

OPEN DUMPS

LANDFILLING

• It is used for disposal of biomedical waste after treatment in incinerator.

• The land is dug as per the waste quantity but then covered with 0.5 metres of a suitable cover material so that access is minimised.

• It should not be close to any water source.

LANDFILL

Sanitary landfills are designed to have at least advantages over open dumps :

• Geological isolation of from the environment,• Appropriate engineering preparation before the

site is ready to accept waste,• Staff present on control operations, and • Organized deposit and daily coverage of waste.

DISPOSAL OF GYPSUM

PRODUCTS

1) Gypsum recycling especially when it is released on large scale especially on industrial

level2)Landfill in a separate cell so that the

liberation of odorous and toxic hydrogen sulphise is minimised.

DEEP BURIAL

• A pit is dug about 2 metres deep,half –filled with waste,then covered with 10-50cm of soil.

• It gets decomposed within a duration of 4-6 months of time.

• It should be impermeable.• It should have no access to animals.• It should not be prone to flood or erosions.

HANDLING OF MONOMER(Methyl Methacrylate)

Health Hazards

• Highly inflammable• Irritant-Headache etc• Pungent Odour• Skin Allergies• Respiratory tract irritation

Handling and Storage

• To be kept away from fire sources• Store this product in a clean,dry and well ventilated

area• Keep this product away from heat and direct sunlight.• Must be stored far from oxiding agents,acids,bases or

polymer initiators.• Do not store for long periods.• Storage temperature must be lower than 15◦C

Personal protection

Personal protective clothing (PPC)1.Gloves a. Disposable vinyl gloves in all patient care areas b. Latex surgical gloves for operative procedures c. Heavy duty thick rubber gloves for waste handlers especially

the nitrile gloves. 2.Masks: Simple, reusable plastic masks to protect health care

workers from splashes 3.Aprons : Full sleeved, knee length cotton aprons must be worn at

all times.

GLOVES

MASKS

EYEWEAR

LAB COAT

Personal Protective Equipment

• Footwear: Gumboots for waste handlers, The trousers must remain outside the gum boots.

SHOE-WEAR

General• Hand washing facility : Soap and water should

be available at all times. • Drinking water: Safe drinking water must be

available for waste handlers working near boilers to prevent dehydration.

• Immunization : Tetanus, Hepatitis B. • Maintenance of health records.

HAND-WASHING

DRINKING WATER

CONTINGENCY PLANNING

It is best if offices prepare sets of written procedures concerning their regulated waste.  Such prepared programs should always list the person or persons responsible in the event of an emergency.

The success of any safety program is highly dependent on proper employee training and employer monitoring.  All office personnel must be well versed in the handling, storage, treatment, and disposal of regulated medical waste.

PUBLIC RELATIONS

A good portion of the population has an aversion to blood (liquid or dried) and medical/dental sharps, especially needles.  Such anxiety also can exist among those charged to collect, haul, and dispose of waste. 

It would be best if properly treated and labeled regulated waste containers were placed within some other type of container (e.g., cardboard boxes) that can more readily conceal the actual contents.  This is an example of “out-of-sight…out-of-mind.” 

SUMMARY

Proper handling, neutralization, and disposal of regulated dental waste are important elements of every dental office’s infection control program.  Correct procedures will help protect office employees and patients, contract workers, and the local community.  An effective program is based on planning, which includes a firm understanding of the regulations that apply in their location.   All office personnel must be knowledgeable as to the correct procedures and the appropriate equipment. .

Dental Color coding

iYellow Bin Red Bin Blue Bin Black BinSolid wastes contaminated with bloood/saliva e.g.cotton rolls,gauzes,gloves,masks,linen dressings,beddings etc

Solid wastes highly contaminated with blood/saliva.e.g.cotton rollsDisposable instruments,suction tips,any tubings.impressions.

SharpsUsed syringesDental wiresScalpel bladesEndodontic filesBursIV setsExtracted teethAnaesthtic carpules.Extracted teeth

Discarded medicines.Chemical wastesAcylic,etchants etcDiscarded ZnOE paste etcGypsum products

Conclusion

From a waste management point of view, the three

Rs – ‘Reduce, Reuse, Recycle’ – They offer a simplified view of the types

of action we must take. They are in order of priority and are often referred to as the

‘WASTE MINIMISATION HIERARCHY’

1.‘Reduce’ means to use less in the first place, for example being waste conscious as a consumer(considering what you buy and not wasting it).

Achieved by• Following good operating procedures• Material substitution• Improved inventory and centralized purchasing

2.‘Reuse’ means to use the same item more than once in its original form. For example, choosing reusable rather than disposable items, and finding alternative uses for items no longer needed for their original use.

Eg: OT Kits containing gowns ,mask, caps, shoe covers, bed sheet can be reused if made of cotton and this can be easily washed and autoclaved

3.‘Recycle’ means to reprocess used products into either the same product or a different one.

• In most cases, manufacturing from recycled materials requires less energy.

• Eg: Reclamation of solvents for reuse(Eg Xylene)• Recycling of Containers• Recyling of materials such as photographic film and

silver from processing chemicals.

Let the wastes of “ the sick ”

not contaminate the lives of “ the healthy “

REFERENCES.

Council on dental materials and devices, Council on dental therapeutics; Infection control in dental office; JADA 97;4:673-677,Oct1978.

Council on dental materials instruments and equipments, Council on dental therapeutics and practice;Infection control recommendations for the dental office and the dental laboratory ; JADA: 116;Feb1988.

Recommended clinical guidelines for infection control in dental education institutions: Journal of Dental Education;55:9;1991.

States act to regulate medical waste:JADA;122:Sep1991. P.L. Fan, Dorthe Arenholt-Bindslev;Environmental issues in

dentistry- mercury;International Dental Journal: 47;2:1997. Nairn H.F.Wilson,EdwardG.Bellinger;Dental practice and the

enviornment,International Dental Journal:48:3;161-166,1998.

Amalgam in dental office wastewater,JADA: 133;585-588;May2002.

ADA Council on scientific affairs Managing silver and lead waste in dental offices,,JADA,134:1095-1096;Aug2003.

KEVIN. R. MCMANUS,P.L.FAN:Purchasing , installing and operating amalgam separators- Practical issues;JADA;134,1054-1065:Aug2003.

ADA Council on scientific affairs Dental mercury hygiene recommendations , :JADA;134,1498-1499;Nov2003.

HAZEL. O. TORRES et al : Modern dental assisting 5th edition . Clifford.M. Sturdevant et al :The art and science of Operative dentistry 3rd edition . Ann Ehrlich et al ; Essentials of dental assisting :2nd edition.