Experts Urge More Caution in the Continued Use of DDT
May 04, 2009
A panel of international scientists is calling for stronger efforts to reduce exposure to DDT in areas where it is still used and in areas where significant contamination remains.
Based on recent studies that show a link between DDT and human health, the panel urges more understanding of the health effects of exposure to the pesticide as well as development of alternatives to using it to control malaria. Scientists from the Oakland-based Public Health Institute (PHI) and University of California at Berkeley (UCB) along with several researchers from African nations expressed their concerns about DDT, following a review of nearly 500 epidemiological studies published online today in the journal Environmental Health Perspectives.
To date, more than 160 countries have signed the Stockholm Convention on Persistent Organic Pollutants, an international treaty banning DDT and 11 other persistent organic pollutants, except when needed for malaria control. In cases where DDT must be used, the Stockholm Convention requires certain procedures and oversight management to minimize humans' exposure to the pesticide and its release into the environment. However, the authors noted DDT's use in controlling malaria is poorly monitored.
It is also not known whether people in countries where malaria control is needed, such as in Africa, have greater vulnerability to DDT effects because of high rates of HIV infections and other health challenges.
"DDT is an example of a problem that has implications for the health of people in this country as well as those living in other countries with fewer resources," said Barbara Cohn, a cancer researcher at PHI's Center for Research on Women's and Children's Health. "Understanding DDT effects will help us avoid future problems and improve the public health worldwide."
The consensus statement issued by the scientists emerged from a conference held near a DDT contaminated site in Central Michigan last spring. The conference was organized by the Pine River Superfund Citizen Task Force, the Center for Responsible Leadership and the Public Affairs Institute of Alma College.Alma College, where the conference took place, is located in St. Louis, Michigan, across the river from a chemical plant which leached massive levels of DDT and other contaminants into the Pine River during the mid-1900's. The U.S. Environmental Protection Agency (EPA) named the Velsicol Chemical Corporation a Superfund site in 1983. Efforts to clean up the surrounding area continue and DDT remains a problem, according to a recent EPA report.
"It's significant that the location of the conference was held at a U.S. Superfund Site, where the legacy of exposure to DDT is still an issue," said Cohn, who studies the impact of DDT exposure in early life on cancer and reproduction. While the researchers say they put their concern about DDT in the context of people dying of malaria--recognizing that DDT can save lives by repelling and killing disease-spreading insects--they based their consensus statement on evidence that suggests that people living in areas where DDT is used are exposed to very high levels of the pesticide.
According to the scientists, there have been few studies published on health effects in these populations."Clearly, more research is needed on the health of populations where indoor residual spraying is occurring, but in the meantime, DDT should really be the last resort against malaria rather than the first line of defense," said Brenda Eskenazi, a professor of public health at UCB and lead author of the review article.
Alternatives to using DDT to control malaria include the use of bed nets, draining sources of standing water or filling them up with soil, and the rapid diagnosis and treatment of malaria cases. In 2006 alone, 880,000 people died from malaria and 247 million others contracted the disease, according to the World Health Organization. Most of the deaths were of young children in Africa.
Environmental Health Perspectives is a peer-reviewed journal published by the National Institute of Environmental Health Sciences.