FOR IMMEDIATE RELEASE
1 March 2007

CONTACT: Jim Tobin
919-653-2582

New Study Identifies Potential Cardiovascular Disease Risk from Carbon Nanomaterials

Environmental Health Perspectives report examines oxidative stress, atherosclerosis

[Research Triangle Park, NC] Respiratory exposure to single-wall carbon nanotubes (SWCNTs) could lead to adverse cardiovascular effects. Researchers at the National Institute for Occupational Safety and Health (NIOSH) in Morgantown, West Virginia, have released findings in the March 2007 issue of Environmental Health Perspectives suggesting that SWCNTs deposited in the lungs could promote cardiovascular damage.

The small size, large surface area, and high reactivity of carbon nanotubes and other engineered carbon nanomaterials offer many useful benefits in the fields of medicine and technology, but these very qualities may also contribute to nanomaterials' toxicity potential. Previous studies indicate that besides damaging the initial contact site, tiny particles can travel throughout the body, possibly causing adverse responses in other areas.

In the current study, the researchers analyzed the association between pulmonary deposition of SWCNTs and resulting systemic toxicity. They introduced SWCNTs into the lungs of transgenic mice to evaluate expression of a surrogate genetic biomarker of oxidative stress. Gene expression was achieved in the lung, aorta, and heart 7 days after exposure, declining to control levels by 28 days after exposure.

The researchers also saw an increase in mitochondrial DNA damage at 7, 28, and 60 days after exposure. Such damage is believed to be an initiating event to atherogenesis, the process by which arteries become clogged.

The team also explored the association between SWCNT exposure, oxidative stress, and atherosclerosis in ApoE-/- mice, a widely used model for human atherosclerosis. Half the mice were fed a regular chow diet, while the others received a high-fat chow diet for the first half of the test period. Although lipid levels in both sets of mice appeared unaffected by the treatment, the high-fat regimen appeared to contribute to greater plaque formation in the aorta and brachiocephalic arteries in mice exposed to SWCNTs.

These results suggest that SWCNTs could potentially influence cardiovascular diseases, although the mechanism of direct or indirect effects is still unclear. The researchers say further studies should evaluate the systemic effects of SWCNTs, particularly under conditions likely to occur in the workplace or environment, such as low-level chronic inhalation exposure.

The lead author of the study was Zheng Li. Other authors included Tracy Hulderman, Rebecca Salmen, Rebecca Chapman, Stephen S. Leonard, Shih-Houng Young, Anna Shvedova, Michael I. Luster, and Petia P. Simeonova. The article is available free of charge at http://www.ehponline.org/members/2006/9688/9688.html.

EHP is published by the National Institute of Environmental Health Sciences (NIEHS), part of the U.S. Department of Health and Human Services. EHP is an Open Access journal. More information is available online at http://www.ehponline.org/. Brogan & Partners Convergence Marketing handles marketing and public relations for EHP, and is responsible for the creation and distribution of this press release.

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