Dartmouth study finds that arsenic inhibits DNA repair

Dartmouth College Office of Public Affairs �?Press Release
Posted 05/26/06 �?Susan Knapp

Dartmouth researchers, working with scientists at the University of Arizona and at the Department of Natural Resources in Sonora, Mexico, have published a study on the impact of arsenic exposure on DNA damage. They have determined that arsenic in drinking water is associated with a decrease in the body's ability to repair its DNA.

Authors of the study, from left to right: Eugene Demidenko, Angeline Andrew, Joshua Hamilton, Margaret Karagas (Photo by Joseph Mehling '69)

"This work supports the idea that arsenic in drinking water can promote the carcinogenic effects of other chemicals," says Angeline Andrew, the lead author and a research assistant professor of community and family medicine at Dartmouth Medical School. "This is evidence that it's more important than ever to keep arsenic out of drinking water."

The study, which was published online on May 10, 2006, in the journal Environmental Health Perspectives, examined the drinking water and measured the arsenic levels in samples of urine and toenails of people who were enrolled in epidemiologic studies in New Hampshire, and in Sonora, Mexico. Andrew and her colleagues examined the data in conjunction with tissue samples from the study participants to determine the effect of arsenic on DNA repair. To further corroborate their findings, the researchers conducted laboratory studies to examine the effects of arsenic on DNA repair in cultured human cell models.

"The DNA repair machinery normally protects us from DNA-damaging agents, such as those found in cigarette smoke," says Andrew. "The concern is that exposure to drinking water arsenic may exacerbate the harmful effects of smoking or other exposures."

Andrew explains that in regions of the United States where the rock contains higher levels of arsenic, the greater the likelihood that drinking water sources contain some potential adverse levels of the toxin. While the levels of arsenic in municipal water systems are regularly monitored, there is no mandated testing of arsenic levels in private wells. This is of particular concern since the regions where arsenic levels are high are in rural regions, such as New Hampshire, Maine, Michigan and some regions of the Southwest and Rockies. Private wells are common in these areas as primary sources of drinking water. (More information on drinking water testing and remediation options can be found from the NH Department of Environmental Services or the US Environmental Protection Agency.)

Andrew's co-authors on this paper are: Jefferey Burgess, Maria Meza, Eugene Demidenko, Mary Waugh, Joshua Hamilton, and Margaret Karagas, all from Dartmouth Medical School, the Department of Environmental and Community Health at the University of Arizona, or the Department of Natural Resources at the Technological Institute of Sonora, Mexico.

The research was supported by funding from the National Institutes of Health, the National Institute of Environmental Health Sciences, the National Cancer Institute, the Dartmouth and Arizona Superfund Programs, and the American Society of Preventive Oncology.

 
 
From:   http://www.dartmouth.edu/~news/releases/2006/05/26.html

Reported by:   http://www.eurekalert.org

Arsenic discharged from landfills, says Dartmouth research
Dartmouth College Office of Public Affairs �?Press Release
Posted 12/02/05 �?Contact Susan Knapp (603) 646-3661

Benjamin Bostick (photo by Joseph Mehling '69)
A group of researchers at Dartmouth has studied the concentrations of toxic metals at the former Coakley Landfill in North Hampton, N.H. They've found that while the level of iron and some other contaminants decreased, the level of arsenic slightly increased. The researchers detail their calculations regarding the geochemical processes at this site over the last ten years in a paper published online on Nov. 23, 2005, by Environmental Science and Technology, a journal of the American Chemical Society.

This research could shed light on how arsenic pollutes ground water near landfills, especially in areas where the landfill's organic material mixes with naturally occurring iron oxides. This process also may explain the high level of arsenic in drinking water in Bangladesh and other areas of Southeast Asia.

"Unfortunately, arsenic appears to come from the interaction of microbes with iron oxides carrying arsenic in the underlying rocks," says Benjamin Bostick, a coauthor on the paper and an assistant professor of earth sciences at Dartmouth. "In the Coakley Landfill, it appears that these microbes increase arsenic concentrations by consuming organic wastes and creating a 'reducing condition' where the oxygen concentration is very low, which is conducive to arsenic release. We think that arsenic contamination caused by the natural degradation of other toxic organic material might be widespread."

The Coakley Landfill was listed in 1986 as an Environmental Protection Agency Superfund Site because of hazardous waste content. The area was capped in 1998, a procedure common in the rehabilitation of landfills. With data collected since 1994, the researchers were able to tie changes in arsenic levels over time to the degradation of benzene and other organic wastes.

Bostick's coauthors on this study include Jamie deLemos, Carl Renshaw, Stefan Stürup, and Xiahong Feng, all with Dartmouth's Department of Earth Sciences.

Funding for this research was provided by the U.S. National Institutes of Environmental Health Sciences Superfund Basic Research Program and the National Science Foundation.
 
 
From:   http://www.dartmouth.edu/~news/releases/2005/12/02.html