Tag Archives: US Centers for Disease Control and Prevention

US National Institute of Occupational Health and Safety sets recommendations for workplace exposure to carbon nanofibers/nanotubes

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Earlier this week, the US National Institute of Occupational Health and Safety (NIOSH) set recommendations for workplace exposure to carbon nanotubes and carbon nanofibers. According to the Apr. 24, 2013 media advisory from the US Centers for Disease Control and Prevention (NIOSH’s parent agency), the recommendations have been issued in the new Current Intelligence Bulletin (CIB) no. 65. From CIB No. 65,

NIOSH is the leading federal agency conducting research and providing guidance on the occupational safety and health implications and applications of nanotechnology. As nanotechnology continues to expand into every industrial sector, workers will be at an increased risk of exposure to new nanomaterials. Today, nanomaterials are found in hundreds of products, ranging from cosmetics, to clothing, to industrial and biomedical applications. These nanoscale-based products are typically called “first generation” products of nanotechnology. Many of these nanoscale-based products are composed of engineered nanoparticles, such as metal oxides, nanotubes, nanowires, quantum dots, and carbon fullerenes (buckyballs), among others. Early scientific studies have indicated that some of these nanoscale particles may pose a greater health risk than the larger bulk form of these materials.

Results from recent animal studies indicate that carbon nanotubes (CNT) and carbon nanofibers (CNF) may pose a respiratory hazard. CNTs and CNFs are tiny, cylindrical, large aspect ratio, manufactured forms of carbon. There is no single type of carbon nanotube or nanofiber; one type can differ from another in shape, size, chemical composition (from residual metal catalysts or functionalization of the CNT and CNF) and other physical and chemical characteristics. Such variations in composition and size have added to the complexity of understanding their hazard potential. Occupational exposure to CNTs and CNFs can occur not only in the process of manufacturing them, but also at the point of incorporating these materials into other products and applications. A number of research studies with rodents have shown adverse lung effects at relatively low-mass doses of CNT and CNF, including pulmonary inflammation and rapidly developing, persistent fibrosis. Although it is not known whether similar adverse health effects occur in humans after exposure to CNT and CNF, the results from animal research studies indicate the need to minimize worker exposure.

This NIOSH CIB, (1) reviews the animal and other toxicological data relevant to assessing the potential non-malignant adverse respiratory effects of CNT and CNF, (2) provides a quantitative risk assessment based on animal dose-response data, (3) proposes a recommended exposure limit (REL) of 1 μg/m3 elemental carbon as a respirable mass 8-hour time-weighted average (TWA) concentration, [emphasis mine] and (4) describes strategies for controlling workplace exposures and implementing a medical surveillance program. The NIOSH REL is expected to reduce the risk for pulmonary inflammation and fibrosis. However, because of some residual risk at the REL and uncertainty concerning chronic health effects, including whether some types of CNTs may be carcinogenic, continued efforts should be made to reduce exposures as much as possible.

The recommended exposure, for those of us who can’t read the technical notation, translates to one microgram per cubic meter per eight-hour workday.  In other words, almost zero. Note that this is a recommendation and not a regulation. H/T Apr. 26, 2013 article by Elizabeth Wiese for USA Today

My Mar. 12, 2013 posting highlights some of the NIOSH research which preceded this recommendation.

Micro needle patches project gets Grand Challenges Explorations grant

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The project being funded with a Grand Challenges Explorations grant (from the Bill & Melinda Gates Foundation) reminds me a lot of the nanopatch that Mark Kendall and his team have been developing in Australia (a project last mentioned in my Aug. 3, 2011 posting). This new initiative comes from the Georgia Institute of Technology and is aimed at the eradication of polio. From the Nov. 7, 2011 news item on Nanowerk,

The Georgia Institute of Technology will receive funding through Grand Challenges Explorations, an initiative created by the Bill & Melinda Gates Foundation that enables researchers worldwide to test unorthodox ideas that address persistent health and development challenges. Mark Prausnitz, Regents’ professor in Georgia Tech’s School of Chemical and Biomolecular Engineering, will pursue an innovative global health research project focused on using microneedle patches for the low-cost administration of polio vaccine through the skin in collaboration with researchers Steve Oberste and Mark Pallansch of the US Centers for Disease Control and Prevention (CDC).

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The goal of the Georgia Tech/CDC project is to demonstrate the scientific and economic feasibility for using microneedle patches in vaccination programs aimed at eradicating the polio virus. Current vaccination programs use an oral polio vaccine that contains a modified live virus. This vaccine is inexpensive and can be administered in door-to-door immunization campaigns, but in rare cases the vaccine can cause polio. There is an alternative injected vaccine that uses killed virus, which carries no risk of polio transmission, but is considerably more expensive than the oral vaccine, requires refrigeration for storage and must be administered by trained personnel. To eradicate polio from the world, health officials will have to discontinue use of the oral vaccine with its live virus, replacing it with the more expensive and logistically-complicated injected vaccine.

Prausnitz and his CDC collaborators believe the use of microneedle patches could reduce the cost and simplify administration of the injected vaccine.

Iwonder if this team working at the microscale rather than the nanoscale, as Kendall’s team does, is finding some of the same benefits, from my August 3, 2011 posting,

Early stage testing in animals so far has shown a Nanopatch-delivered flu vaccine is effective with only 1/150th of the dose compared to a syringe and the adjuvants currently required to boost the immunogenicity of vaccines may not be needed. [emphases mine]

I find the notion that only 1/150th of a standard syringe dosage can be effective quite extraordinary. I wonder if this will hold true in human clinical trials.

If they get similar efficiencies at the microscale as they do at the nanoscale, the expense associated with vaccines using killed viruses should plummet dramatically. I do have one thought, do we have to eradicate the polio virus in a ‘search and destroy mission’? Couldn’t we learn to live with them peacefully while discouraging their noxious effects on our own biology?