Nanomaterial Safety

Nanomaterial SafetyCreated By: Dean MarinchekSupervised By: Dr. Larry Miller

NanotechnologyNanotechnology is the engineering and manipulation of materials at the molecular levelThe dimension of nanomaterials are between 1 and 100 nanometers1nm is 1 billionth of a meterA human hair is 50,000 nanometers in diameterNanotechnologyParticles created at the nanoscale have different chemical and physical properties than larger particles of the same materialCarbon NanotubesCarbon Nanotubes (CNTs) in particular have unique electrical, mechanical, and thermal properties with a large potential in electronics, aerospace, and many other industries. CNTs exist in two forms, single-wall (SWCNTs) and multi-wall (MWCNTs)

Potential Health HazardsDue to the relatively new nature of nanotechnology, research is still being conducted on the health hazardsTwo facts must be known to determine if workers are at riskThe type and concentration of nanoparticles in the workplaceThe specific properties of the nanoparticles that could potentially affect the bodyPotential Health HazardsWorkplace tasks that increase the risk of exposureHandling powders of nanomaterialsMaintenance on equipment and processes used to produce or fabricate nanomaterials and the cleaning-up of spills and waste material containing nanomaterialsCleaning of dust collection systems used to capture nanoparticlesMachining, sanding, drilling, grinding, cutting, or other mechanical disruptions of materials containing nanoparticles

Research on Health RisksIn lab animals, some nanoparticles reach blood, brain, and other organs when inhaledThis causes adverse effects such as inflammation and fibrosis in the lungs and other organsRecent studies have shown that size, surface area, surface chemistry, solubility, and possibly shape all play a role in determining the potential to cause harmResearch on Health RisksStudies in workers exposed to aerosols of some manufactured or incidental microscopic and nanoscale particles have reported adverse lung effects including lung function decrements and obstructive and fibrotic lung disease CNT Specific ResearchCNTs may contain metal catalysts as byproducts of their production, which could contribute to their toxicity

Regardless of the process by which CNTs were synthesized and the types and amounts of metals they contained, CNTs were capable of producing inflammation, epithelioid granulomas (microscopic nodules), fibrosis, and biochemical/toxicological changes in the lungs

CNT Specific ResearchSWCNTs have been shown to produce adverse effects at mass doses at which ultrafine carbon black did not produce adverse effects. Both are carbon based but SWCNTs have a unique structureSWCNTs were shown to be more toxic than quartz, which is considered a serious occupational health hazard if it is chronically inhaledCNT Specific ResearchMWCNTs have been shown to produce lung lesions similar to those observed in studies with SWCNTsThese results indicate that, if CNT particulates reach the lung in sufficient quantity, they will produce a toxic response CNT Specific ResearchThese studies do not answer the important health risk question of whether airborne CNT particles can reach the lungs, because in all cases the CNTs were placed inside the lungs of animals, not inhaled

CNT Specific ResearchThe lungs arent the only organ affected by CNTsStudying the effects on mouse hearts, scientists found damage to the DNA, an increase of plaque in the aortic area, and an increase of atherosclerotic lesions in the brachiocephalic arteries

CNT Specific ResearchThe risk of nanotubes is often compared to that of asbestosExposure to asbestos is not the same exposure that could occur with CNTs. According to Lance Criscuolo, president of Zyvex Performance Materials, an Ohio-based company that uses CNTs, CNTs, once mixed into a polymer matrix, are bound up and no longer releasable into air or water. CNT Specific ResearchThis means the workers in most concern are the ones actually creating the CNTs and putting them into plasticsThe EPA is most concerned with the fibrous, dry powder and less concerned with CNTs that are integrated into polymer materials, said David Burton, General Manager, Applied Sciences Inc.

CNT Specific ResearchCriscuolo said Zyvex has done air monitoring studies throughout the entire process. These studies were performed by a certified company. They were not able to detect any significant amount of CNTs in the airstream. This testing was also included in the composite cutting and sanding area. This provides some solid evidence that once CNTs are encapsulated within a resin system, that they are not able to become free from that system. How Can Workers Be ExposedInhalationThis is the most common and most dangerous type of exposureIt has been determined that the factors that have a role in pulmonary toxicity include, but are not limited to:particle number and size distributiondose of particle to target tissuesurface treatment on particlesHow Can Workers Be Exposedthe degree to which engineered nanoparticles aggregate/agglomeratesurface charge on particlesparticle shape and/or electrostatic attraction potentialmethod of particle synthesis i.e., whether formed by gas phase or liquid phase synthesis and post-synthetic modifications, which likely influence aggregation behavior.How Can Workers Be ExposedIngestionNanoparticles may enter the gastrointestinal tract as they are cleared from the upper respiratory tract and they appear to pass through relatively quicklyIt is known that some nanoparticles, specifically nanotubes and nanofibers, can undergo surface oxidation and length shortening in presence of strong acid conditions, so it is possible that the acidic gastric environment will not only be unable to destroy the nanoparticles, but it may functionalize and shorten the particles to a point that their toxicological effect on the surrounding environment might change drasticallyHow Can Workers Be ExposedDermalSome studies show that nanoparticles may penetrate the skin due to their small size. This possibility is being investigated

Can Nanoparticles Be Measured?Traditional industrial hygiene sampling methods can be used to measure airborne nanoparticlesScientists are developing more sensitive and specific sampling techniquesCan Nanoparticles Be Measured?Workers need the development of sensors that simultaneously detect airborne nanoparticles and determine their potential to generate reactive oxygen species- possibly providing early indications of harm

Airborne Exposure LimitsThese materials are used in the production of the CNTsControlling ExposureEmployers should use engineering controls to reduce workers exposure to nanoparticlesSource enclosureIsolating the generation source from the worker Local exhaust ventilation systemsExhaust ventilation systems that use HEPA filters are effective in removing nanoparticles(See next slide)

Controlling ExposurePrevent food and beverages in workplaces where nanomaterials are handledIts a good idea to systematically evaluate exposure to ensure that control measures are working properly and that workers are being provided the appropriate personal protective equipment

Controlling ExposureExisting U.S. regulations do not specifically address nanomaterialsThe EPA apparently intends to designate CNT releases into US waters as a significant new use, which would likely trigger a major amount of additional compliance record-keeping for companiesFor a specific examples of a protocol for handling of nanotubes see:PROTOCOLS FOR HANDLING NANOTUBE COMPOSITES.docC-nano Material Safety Data Sheet.pdf

Government RegulationsEPA is issuing significant new use rules (SNURs) under section 5(a)(2) of the Toxic Substances Control Act (TSCA) for two chemical substances which were the subject of Premanufacture Notices (PMNs). The two chemical substances are identified generically as multi-walled carbon nanotubes (MWCNT) (PMN P08177) and single-walled carbon nanotubes (SWCNT) (PMN P08328). This action requires persons who intend to manufacture, import, or process either of these two chemical substances for a use that is designated as a significant new use by this final rule to notify EPA at least 90 days before commencing that activity. EPA believes that this action is necessary because these chemical substances may be hazardous to human health and the environment.Government RegulationsExclusions include:After they have been completely reacted (cured);Incorporated or embedded into a polymer matrix that itself has been reacted (cured); or,Embedded in a permanent solid polymer form that is not intended to undergo further processing except for mechanical processing.Safety EquipmentPersonal Environmental Monitors can detect the amount of nanomaterials in the air that a worker is exposed toThis is crucial in the production of nanomaterialsExamples of PEMs

Safety EquipmentInhalation and ingestion protection can be provided by respiratorsMust be(NIOSH)-approved air-purifying, tight-fitting full-face respirator equipped with N100 filters)Ingestion protection can be aided by frequent washing of the hands and maintaining a clean work environmentDermal penetration can be prevented by the use of nitrile gloves and full-coverage lab coatsCleanup and DisposalAccidental spills of nanotubes are inevitable during their production, and the massive use of nanotubes-based materials could lead to increased environmental pollutionResearch is being conducted to help aid in this situationScientists have found that CNTs deteriorate when exposed to the natural enzyme horseradish peroxidase, also called HRPOnce fully developed the method could be administered as easily as chemical cleanups in todays labsCleanup and DisposalThe use of HEPA filtered vacuums and/or wet wiping techniques should be use often to keep the workplace cleanWorkers must wash hands frequentlySetting up conforming hazardous waste management practices is a good ideaConclusionAll in all, nanotechnology is a fun and exciting new scienceWith all new technology comes risksIt is recommended to take a prudent approach to manufacturing and to minimize exposure until more information available