NIOSH Proposes Exposure Limits
for Carbon Nanotubes
BY Gwyneth K. Shaw | DEC 7,
2010 11:20 AM
(NHI Nanoblog) The National Institute for
Occupational Safety and Health has put out draft recommendations for
protecting workers from carbon nanotubes and nanofibers, including the
first exposure limit level for the tiny materials.
division of the federal Centers for Disease Control, has been a leader
in conducting and analyzing research about a variety of nanomaterials,
with an eye on creating a framework for workplace safety. Carbon
nanotubes=97super-small cylinders of carbon that are prized for their
strength and ability to both insulate and conduct electricity=97have
been on the agency=92s radar screen for some time.
CNTs are a
hot item in the nanotechnology field, and are becoming increasingly
common, in things like electronics, lithium-ion batteries, and solar
They=92ve also raised a number of safety concerns,
mostly because they=92re small enough to be inhaled=97but often, not big
enough to be seen.
Research has shown that once in the lungs, nanotubes
can lodge there. In mice, the tubes are known to cause fibrosis. And the
substance can reach the same space in the lungs where mesothelioma, a
serious lung disease that=92s mostly associated with asbestos exposure,
But only two studies offered useful information
about what carbon nanotubes do to people, said said Paul Schulte,
director of the Education and Information Division at NIOSH.
proposing a limit of seven micrograms of nanotubes or nanofibers per
cubic meter of air over the course of an eight-hour shift, and
encourages employers to work to keep exposure below even that level.
Seven micrograms is basically the smallest amount that=92s detectable
using the agency=92s sampling mechanism, Schulte said.
the agency wants manufacturers to take a number of precautions, ranging
from educating workers who might be exposed to the materials to using a
host of controls to prevent the substances from reaching employees in
the first place. These include using proper ventilation in rooms where
the tubes are produced as well as adding personal protection, such as
respirators, protective suits and gloves, for workers when the
environmental controls are not enough to get the exposure level below
the proposed limit.
Workers also should change their clothes and wash
any exposed areas before heading home, according to the
Every company that makes these substances might not
have the equipment needed to protect their workers to this extent,
Schulte said, but the recommendation is definitely =93doable=94 for the