Study Suggests Low-Dose Arsenic Compromises Immune Response to Influenza A

First author Courtney D. Kozul and colleagues reported that mice exposed to 100 parts per billion (ppb) of arsenic in drinking water had altered immune responses, higher viral titers and more severe symptoms in response to influenza A infection compared with infected mice that were not exposed to arsenic.

“In this study, we show that chronic low-dose arsenic exposure can profoundly alter the response to influenza A (H1N1) infection [in mice],” wrote Kozul and colleagues. “Understanding the role of arsenic in response to such viral challenges [in humans] will be important in the overall assessment of the public health risk.”

Flu is a major cause of morbidity and mortality worldwide. An estimated 5-15% of the global population will contract influenza annually, resulting in over 3-5 million hospitalizations and 250,000-500,000 deaths.

Worldwide, millions of people drink water containing arsenic at levels above the U.S. EPA’s guideline of 10 ppb. In certain areas in the U.S. West, Midwest, Southwest and Northeast, people drinking contaminated well water may be exposed to arsenic levels ranging from 50 to 90 ppb or even higher. In some Asian countries, levels may exceed 3,000 ppb.

Alterations in response to repeated lung infection such as those observed by Kozul and colleagues may also contribute to other chronic illnesses, such as bronchiectasis, which is elevated by arsenic exposure in epidemiologic studies. Chronic exposure to arsenic has been associated with many diseases, including lung, liver, skin, kidney and bladder cancer; cardiovascular disease; diabetes; and reproductive and developmental defects.

“With the current concern about the H1N1/influenza A virus and the potential effect of H1N1 spreading in areas where arsenic exposure is common, this study is both extremely timely and highly relevant,” said EHP editor-in-chief Hugh A. Tilson, PhD. “It is expected that the effects of arsenic exposure on the immune response to viral infection are complex, and therefore it is likely that several mechanisms are contributing to the adverse outcomes observed in the arsenic-exposed mice.”

Other authors of this paper included Kenneth H. Ely, Richard I. Enelow and Joshua W. Hamilton. This work was funded by the Superfund Basic Research Program of the National Institute of Environmental Health Sciences (NIEHS)/National Institutes of Health.

The article is available free of charge at http://www.ehponline.org/docs/2009/0900911/abstract.html

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