The results were reported during a recent meeting of the Society of Toxicology. The study was the first to show that MWCNT is a cancer promoter in a laboratory experiment.
In the study, mice were exposed by inhalation to MWCNT to determine whether the tiny particles have the potential to initiate or promote cancer. Initiate was defined as the ability of a substance to cause mutations in DNA that can lead to tumors while promote means the ability of a substance to cause cells that have already sustained such DNA mutations to then become tumors.
One group of mice was injected with a known cancer initiator while the others were given a saline solution as a control group. They were then exposed by inhalation either to air or a concentration of MWCNT. The study indicated MWCNT is a cancer promoter but not that MWCNT alone causes cancer in the mice.
"Inhalation exposure most closely resembles the exposure route of greatest concern in the workplace," according to a post on the NIOSH science blog. "This research is an important step in our understanding of the hazard associated with MWCNT."
Before determining whether MWCNT poses an occupational cancer risk, researchers need more information about actual exposure levels and the types and nature of the MWCNT being used in the workplace and how that compares to the material used in the study.
The mice in the study were exposed to one type of MWCNT through inhalation at a concentration of 5 milligrams per cubic meter of air for five hours per day for 15 days. The researchers say studies are under way to learn more about actual worker exposure and to develop guidance on how to contain and control processes to eliminate exposures.
"Until more is known, NIOSH's existing recommendations for prudent workplace practices offer our guidance on controlling exposures to MWCNT and other nanomaterials, based on our current scientific knowledge," the post says. "Containment, local exhaust ventilation, filtration, and use of personal protective equipment, including respirators, have proven effective in reducing exposure and are recommended as prudent practices."
Read more at the WorkersComp Forum homepage.
April 15, 2013
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