March 23, 2009 The Pump Handle 0Comment

We’ve written before about the way that use of nanomaterials in consumer products is outpacing research on the materials’ occupational and environmental health effects. So, it’s good to see that the National Institute for Occupational Safety and Health is contributing a piece to the puzzle, and getting the word out to the public about their research.

NIOSH scientists Vincent Castranova, Ann Hubbs, Dale Porter, and Robert Mercer conducted a study in which laboratory mice inhaled liquid containing multi-walled carbon nanotubes (MWCNTs). Attendees at last week’s Society for Toxicology meeting got to hear about the study results, and so the scientists figured that the general public ought to be able to learn about them, too.

In their post on the NIOSH Science Blog, the authors stress that their results haven’t been formally peer-reviewed, although they will be once articles on the study are submitted to journals. I’m glad they didn’t wait for the formal peer-review process to alert the public to their findings, which are worrisome but not surprising, given what we learned last year about carbon nanotubes having effects similar to those of asbestos fibers when injected into the abdominal cavities of mice.

Here’s what Castranova et al found:

The research showed inflammation in the lungs of the mice, and fibrosis in their lungs, which persisted following exposure. Such effects are similar to the interstitial pulmonary fibrosis reported previously by NIOSH researchers using single-walled carbon nanotubes.

Most significantly in terms of generating new knowledge, the study demonstrated the ability of MWCNTs to migrate from the lungs to the pleura (the tissue that surrounds the lungs). The preliminary findings are the first to demonstrate that carbon nanotubes aspirated by laboratory mice can actually migrate from the alveoli in the lungs (the tiny structures in the lung that are critical for gas exchange), through the lungs, to the pleura. The preliminary findings offer significant new evidence of MWCNTs appearing to behave like durable fibers in that they translocate to the pleura.

The authors then point out that these “preliminary findings are not definitive” in answering questions about whether nanotubes would migrate to the pleura in workers who inhale them, or whether migrating to the pleura would cause mesothelioma (the disease that’s still killing asbestos-exposed workers and members of communities like Libby, Montana). The authors also identify shortcomings in their study and describe additional research that’s needed. Then they give an understated warning:

In the interim, as we prepare them for peer-reviewed publication and look ahead to subsequent research needs, these new preliminary findings reinforce the need to adopt a system of prudent risk management practices, including a continued rigorous approach to controlling occupational exposures among workers during the production and use of MWCNTs.

Given that the nanotech genie is unlikely to go quietly back into its bottle, “prudent risk management practices” are probably the best we can hope for right now. The reference to a “continued rigorous approach to controlling occupational exposures” seems a little optimistic, given that a survey of workplace safety programs at nanomaterials firms and laboratories found them to be uneven and in need of additional guidance. (See Olga Naidenko’s post on workplace nano safety practices for more.)

Nanotubes may not turn out to be as deadly as asbestos, but we shouldn’t wait for more research to start reducing workers’ and consumers’ exposure to them. Quick action now could avert enormous expense and suffering in the future.

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