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Vol. 14 Issue 2, Spring/Summer 2009
By Suzanne Snedeker, Ph.D., Associate Director for Translational Research, BCERF
In the Spring 2008 issue of The Ribbon, I shared with readers my experiences attending the Eugene Kenaga International DDT Conference, where I joined other scientists and local community advocates to discuss the health effects of DDT use. My presentation was on the evidence of DDT’s effects on the risk of cancer and diabetes. The conference took place at Alma College in Michigan near one of the largest Superfund sites for DDT contamination (Velsicol Chemical Corporation Plant) (see http://envirocancer.cornell.edu/Newsletter/articles/v13DDTLegacy.cfm).
Presenters at the conference were urged by Dr. Edward Lorenz, one of the organizers, to write a review of the health consequences of DDT exposure in humans and a consensus statement reflecting the presentations and discussions that took place in Alma. Participating students and advocates (organized as The Pine River Task Force) were concerned with the legacy of DDT’s effect in their own community, as well as the consequences of the reintroduction of DDT for malaria control in Africa and other areas affected by the disease, the need for continued research on health effects in exposed populations, and the importance of seeking alternatives to DDT.
Under the leadership of Dr. Brenda Eskenazi (who presented on neurological effects of DDT exposure in children) and her colleagues from the University of California at Berkeley, those who presented at the conference collaborated over many months to develop a manuscript for publication. I am pleased to have served as a co-author and happy to tell Ribbon readers that the paper was recently published this May in the scientific journal, Environmental Health Perspectives. This is a public access journal and the entire manuscript is available online at: http://www.ehponline.org/members/2009/11748/11748.pdf
The authors examined nearly 500 scientific studies to develop a comprehensive and cohesive analysis of research to date on the health consequences of DDT use. The review also identifies data gaps of what we still need to know about exposure and health effects in at-risk populations, especially children and pregnant women. I co-authored the sections on the cancer risk of DDT with Dr. Barbara Cohn, and wrote the section on emerging evidence that DDT may be linked to an increased incidence of diabetes.
The review presents the entire scope of the evidence on cancer risk, discussing studies showing both positive and negative associations. For instance, while early life exposure to DDT has been linked to a higher risk of breast cancer (in a study authored by Dr. Cohn), as well as to increased risk of cancer of the liver and pancreas, DDT exposure does not appear to increase the risk of cancer of the colon, lung, bladder, prostate, uterus, or stomach.
The review highlights many other areas of health concern, including effects on spontaneous abortion, development of the nervous system in children exposed to DDT, and consequences in adult life, including decreased quality of semen in men. The paper points out the need for more research, including studies to address whether DDT exposure affects the onset of puberty and different endpoints that characterize puberty, as well as the need to understand effects on the immune system, especially in areas that have high rates of HIV. There is still little information available on actual body burdens of DDT in malaria-endemic countries where DDT has been reintroduced (used in residual spraying of interior walls of dwellings). There is even less information on health effects of currently exposed populations, and a continuing need to monitor populations that have been exposed historically, either through direct use or environmental contamination (like the Pine River site).
Given the health consequences of DDT presented in our paper, there is not only the need to conduct more rigorous research on seeking alternatives to DDT for malaria control, but the alternatives must also be evaluated for potential adverse effects on the environment and people, especially in areas where malnutrition and HIV are endemic. For instance, there is a paucity of information on whether use of a DDT alternative, pyrethroid pesticides, has human health consequences in exposed populations. The authors recommend that malaria-plagued countries need to be assisted so they can evaluate and use other methods for reliable malaria control, and that the global community bears the responsibility to carefully monitor exposure to DDT and continue to evaluate health consequences.
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