Wednesday, August 11, 2010

Why are Nanoparticles a Health Concern?

Little is known about the health effects of nanoparticles on workers. Because of their very small size, nanoparticles (and ultrafine particles) may present unique safety and health concerns which are not present in larger-sized particles. Upon inhalation, they are deposited in the lungs to a greater extent than larger respirable particles. In experimental studies, these small-sized particles were shown to pass through skin, enter the bloodstream from the lungs, cross cell membranes, and even travel through nerves directly into the brain. Some studies have also shown that, for a given mass dose, the toxicity increases as the particle size decreases due to increased surface area.

At this point, very little is known about the potential safety hazards of nanomaterials beyond those associated with traditional materials. Combustible nanoscale materials could present a higher risk of fire and explosion than a similar quantity of coarser material. Depending on their composition and structure, some nanomaterials may initiate catalytic reactions and increase their fire and explosion potential in a way that would not be anticipated from their chemical composition

If appropriate, respiratory protection can supplement other control measures to further reduce worker exposure. At this point, the National Institute for Occupational Safety and Health (NIOSH) believes that NIOSH-certified respirators should provide the expected levels of protection if properly selected and fit tested.

Nanoparticles can be controlled using methods similar to those typically used with fine particles: engineering controls, good work practices, proper housekeeping, and respiratory protection. Enclosing the process can isolate the particles. Properly designed local exhaust ventilation (LEV) will capture the particles at the source, keeping them out of the general work environment and the worker’s breathing zone.

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