Smokers who are exposed to arsenic may have a higher chance of getting lung cancer than other smokers, but the link isn't clear—and no one knows how arsenic and smoke might interact. Researchers at the University of Cincinnati are working with mice to figure out how arsenic and tobacco might cooperate.

What the researchers wanted to know: Does arsenic make it easier for benzo[a]pyrene, a chemical in cigarette smoke, to cause cancer?

What they did: Mice were given benzo[a]pyrene, arsenic, neither, or both. Arsenic was given in drinking water, and benzo[a]pyrene was put on their skin. After four consecutive days of benzo[a]pyrene treatment, the mice were killed and samples were taken from their skin, lungs, spleen, and bladder for DNA analysis.

What they found: The arsenic was at such low concentrations that the mice drinking arsenic-containing water did just fine—but even that small amount of arsenic was enough to make benzo[a]pyrene more likely to bind to DNA in the lungs. Benzo[a]pyrene causes cancer by binding to DNA and mutating it.

What it means to you: Even low levels of arsenic may make cigarette smoke more dangerous; the arsenic exposure in this study was estimated to be lower than levels permitted in the workplace.

Caveats: Mice are not humans.

Find out more: Toxicological profile of arsenic http://www.atsdr.cdc.gov/

About benzo[a]pyrene in the environment, from the EPA http://www.epa.gov/safewater/

Read the article: Evans, C.D. et al. "Effect of Arsenic on Benzo[a]pyrene DNA Adduct Levels in Mouse Skin and Lung. Carcinogenesis. April, 2004, Vol. 25, No. 4, pp. 493-497.