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New Study Links Ag Pesticide to Interference in Sexual Development
(Beyond Pesticides, December 8, 2003)
Male school children exposed to the highly toxic insecticide endosulfan showed delayed sexual maturity compared with similar children who were not exposed, according to a study published in the December 2003 issue of the peer-reviewed journal Environmental Health Perspectives (EHP). This study adds to the body of evidence that has raised health concerns for decades. According to the study, Effect of Endosulfan on Male Reproductive Development, endosulfan also appears to interfere with sex hormone synthesis, according to results of the study of males aged 10-19 years in a community of cashew plantations in northern Kerala, India. Although endosulfan is no longer made in the United States, the authors say an estimated 1.4-2.2 million pounds are used in the United States. The issue has been brewing in India, where the study data was collected, and has been reported as the endosulfan conspiracy. In August 2002, Beyond Pesticides reported that the high court of India reinstated a ban on endosulfan after reports showed contamination of villages sprayed with the chemical.

The U.S. Agency for Toxic Substances and Disease Registry (ATSDR) reports the following: Endosulfan affects the central nervous system and prevents it from working properly. Hyperactivity, nausea, dizziness, headache, or convulsions have been observed in adults exposed to high doses. Severe poisoning may result in death. Studies of the effects of endosulfan on animals suggest that long-term exposure to endosulfan can also damage the kidneys, testes, and liver and may possibly affect the body's ability to fight infection ATSDR says that the cancer data is inconclusive. Endosulfan is classified as an organochlorine, the family of pesticides such as DDT and chlordane.

When EPA "reregistered" or reevaluated endosulfan in November 2002, the agency wrote, "[T]here is evidence (effects observed in a submitted chronic oral toxicity study in rats) that endosulfan acts as an endocrine disruptor. However, further investigation is necessary to determine the relevance and impact of such findings on public health." At that time, the agency adopted some exposure mitigation measures but allowed extensive uses to continue.

Endosulfan is a broad spectrum contact insecticide and acaricide registered for use on a wide variety of vegetables, fruits, cereal grains, and cotton, as well as ornamental shrubs, trees, vines, and ornamentals for use in commercial agricultural settings. Total average annual use of endosulfan is estimated at approximately 1.38 million pounds of active ingredient (lbs. ai), according to EPA and registrant estimates. Crops with the highest average percent drop treated are: squash (40%), eggplant (41%), cantaloupe (31%), sweet potato (31%), broccoli (26%), pears (20%), and pumpkins (20%). Crops with the highest sales in 2001 include: cotton (14.2%), cantaloupe (13.2%), tomatoes (12.2%), and potatoes (8.15%).

Researchers evaluated 117 boys in a village where endosulfan has been aerially sprayed for more than 20 years and 90 comparable boys from a nearby village with no such exposure history. For each group, the researchers performed physical examinations and recorded clinical history, sexual maturity rating, and blood levels of various hormones. The study found a higher prevalence of congenital abnormalities related to testicular descent in the study group, but it was not statistically significant due to a small sample size.

"Our study results suggest that endosulfan exposure may delay sexual maturity and interfere with hormone synthesis in male children," the study authors write. "The practice of aerial spraying of endosulfan was discontinued in December 2000. Serum endosulfan residue levels were significantly higher in the study population than in the control group even 10 months after the last aerial spray."

Endosulfan has been banned in several countries, including Cambodia, Colombia, Germany, Sweden, Norway, Indonesia, and others. Its use is severely restricted in at least 20 other countries.
Commenting on the study, Dr. Jim Burkhart, science editor for EHP, says, "This is the first human study to ever measure the effects of endosulfan on the male reproductive system. Decades of spraying this pesticide, and only this pesticide, on the village provided a unique opportunity to analyze its impact. Although the sample size is somewhat limited, the results are quite compelling."

History
Endosulfan was first registered as a pesticide in the U.S. in 1954 to control agricultural insect and mite pests on a variety of field, fruit, and vegetable crops. A Registration Standard dated September 17, 1981, and a Guidance Document dated April 1982 were issued for endosulfan, which required additional generic and product-specific data for the manufacturing products of the technical registrants. Since the Guidance Document was issued, there have been seven data call-in notices generated: 10/23/85, 5/19/86, 5/27/86, 1/30/87, 6/19/87, 9/02/92, and 5/10/94 concerning the potential formation of chlorinated dibenzo-p-dioxins and dibenzofurans in technical endosulfan products. An additional DCI was issued in October 1994, which primarily concerned residue chemistry data deficiencies.

Further, in 1991, the technical registrants amended labels to incorporate a 300-foot spray drift buffer for aerial applications between treated areas and water bodies. This setback was adopted in order to address concerns about contamination of water and risks to aquatic organisms. In 2000, the technical registrants amended technical product labels to remove all residential use patterns. Currently, there are 94 endosulfan products registered.

Study Authors
The lead author on the study was Habibullah Saiyed of the National Institute of Occupational Health (Indian Council of Medical Research). Other authors were Aruna Dewan, Vijay Bhatnagar, Udyavar Shenoy, Rathika Shenoy, Hirehall Rajmohan, Kumud Patel, Rekha Kashyap, Pradip Kulkarni, Bagalur Rajan, and Bhadabhai Lakkad.

EHP is the journal of the National Institute of Environmental Health Sciences, part of the U.S. Department of Health and Human Services. More information is available online at http://www.ehponline.org/.
Editor's note: Full copies of both reports are available by fax or e-mail (PDF format) to media at no charge. Go to www.ehponline.org/press, call 919-541-2359, or e-mail adams6@niehs.nih.gov.