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Government issues new exposure level recommendations for nanomaterials


Carbon nanotubes and carbon nanofibers have led to various lung ailments in rodents during test studies. Researchers concerned about similar effects on humans have issued new recommendations to protect workers.

The National Institute for Occupational Safety and Health says the recommendations provide practical guidance to incorporate prudent management of the materials into everyday workplace practice. The recommendations come as the demand for nanomaterials is expected to grow during the next decade, especially for use in medical devices, structural materials, consumer goods, and energy-saving products.
CNTs and CNFs are "man-made elongated particles made of sheets of pure carbon that are about a thousand times smaller than a human hair," according to NIOSH. They are just two of the types of nanomaterials created through nanotechnology, described as the manipulation of matter on a microscopic scale.
Tests on rodents exposed to low-mass doses of CNTs and CNFs showed adverse lung effects, including pulmonary inflammation and rapidly developing persistent fibrosis. NIOSH says it cannot determine how many workers are potentially exposed but says they are used in products such as plastics and ceramics, paints and coatings, textiles, and electronics.
NIOSH recommends employers in companies that manufacture or use them:
* Reduce worker exposures to airborne concentrations of those materials to no more than 1 microgram per cubic meter of air as a recommended exposure limit -- the lowest airborne concentration that can be accurately measured.
* Apply strategic approaches for controlling occupational exposures, especially engineering controls that enclose processes where CNTs and CNFs could be released into the air "such as transfer of the dry, fine powders from one container to another.
* Educate and train workers on safe handling and on the proper use of engineering and administrative controls and safe work practices.
* Establish health surveillance and medical screening programs to help identify early signs of respiratory disease.
"As nanotechnology continues to expand into every industrial sector, workers will be at an increased risk of exposure to new nanomaterials," NIOSH said. "NIOSH's recommendations are expected to assist industry in establishing good risk management practices for controlling occupational exposures to free, unbound CNTs and CNFs during their manufacture and industrial use."

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