Pesticide Endosulfan Delays Male Sexual Maturation

RESEARCH TRIANGLE PARK, North Carolina, December 5, 2003 (ENS) - Exposure to the pesticide endosulfan damages developing male reproductive organs and hormones, according to the first human study to assess the effects of this chemical on male sexuality. Boys in India who were exposed to endosulfan showed delayed sexual maturity compared with similar children who were not exposed, the new research indicates.

Endosulfan also appears to interfere with sex hormone synthesis, according the study of males aged 10 to 19 years in a cashew plantation community in northern Kerala state.

The lead author on the study was Dr. Habibullah Saiyed of the National Institute of Occupational Health, which is associated with the Indian Council of Medical Research.

Researchers evaluated and compared 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.


Beetle devours cashew leaves, a reason for using endosulfan. (Photo by P. Cenini courtesy FAO)
For each group, the researchers performed physical examinations and recorded clinical history, sexual maturity rating, and blood levels of various hormones. The study group showed a higher prevalence of congenital abnormalities related to testicular descent than the control group, but it was not statistically significant due to the small sample size.

"Our study results suggest that endosulfan exposure may delay sexual maturity and interfere with hormone synthesis in male children," Dr. Saiyed and his coauthors 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," they write.

U.S. federal public health agencies are taking note of this research. The study is contained in the December issue of the peer reviewed journal "Environmental Health Perspectives" (EHP) published by the National Institute of Environmental Health Sciences, part of the U.S. Department of Health and Human Services.

Although endosulfan is no longer made in the United States, the chlorinated insecticide is currently registered to control insects and mites on 60 U.S. crops, including squash, pecans, and strawberries. An estimated 1.4 to 2.2 million pounds are used in the United States annually.

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," Burkhart said. "Although the sample size is somewhat limited, the results are quite compelling."

Classified as an organochlorine, in the same family of pesticide as DDT and dieldrin, endosulfan and its breakdown products are persistent in the environment with an estimated half-life of nine months to six years. It is one of the most commonly detected pesticides in U.S. water, found in 38 states.


The sexual maturation of young males is harmed by endosulfan exposure. (Photo credit unknown)
Exposure to endosulfan happens mostly from eating contaminated food, but may also occur from skin contact, breathing contaminated air, or drinking contaminated water, according to the federal agency that evaluates the human health effects of exposure to hazardous substances in the United States, the Agency for Toxic Substances and Disease Registry (ASTDR).

"We do not know if endosulfan can affect the ability of people to have children or if it causes birth defects," the ASTDR says. "Large amounts of endosulfan damaged the testes of animals, but it is not known if this damaged their ability to reproduce. Some birth defects have been seen in the offspring of animals ingesting endosulfan during pregnancy."

In addition to its effects on the sexual development of males, 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, according to the ASTDR, which warns that severe poisoning may be fatal. Scientists do not know whether or not endosulfan causes cancer.

Studies of the effects of endosulfan on animals suggest that long term exposure to the pesticide can also damage the kidneys, testes, and liver and may possibly affect the body's ability to fight infection. The ASTDR says it is not known if these effects also occur in humans.

Endosulfan enters the air, water, and soil during its manufacture and use. When sprayed on crops, the spray may travel long distances before it lands on crops, soil, or water.

Endosulfan on crops usually breaks down in a few weeks, according to the ASTDR, but the pesticide sticks to soil particles and may take years to completely break down.

Endosulfan does not dissolve easily in water. Endosulfan in surface water is attached to soil particles floating in water or attached to soil at the bottom. The pesticide can build up in the bodies of animals that live in endosulfan contaminated water.

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.

In India, endosulfan is widely used on many crops. Alarm over the health and environmental effects of the pesticide intensified in 2002 when a report on the pesticide appeared in “Down to Earth” a monthly journal from Centre for Science and Environment (CSE), New Delhi.

The report linked the spraying of endosulfan with the high incidence of deformities and diseases in the Kerala cashew plantation village of Padre in the Kasaragod District.


This girl, who lives near a cashew plantation in the Kasaragod District of Kerala, has developed a swelling under her arm. (Photo courtesy Centre for Alternative Agricultural Media)
The Plantation Corporation of Kerela had been spraying endosulfan since the mid-1970s on its cashew plantations. The CSE analysis showed high levels of residue of pesticide in the samples. As soon as the news appeared in the national media, the National Human Rights Commission asked the government agencies, including the Indian Council of Medical Research, to act.

Both the national and the Kerala state governments banned the aerial spraying of endosulfan, and as of December 2000 no more spraying occurred, but the pesticide still remains in soil and water.

But the agricultural and pesticide industries fought the rulings. The industry commissioned the Fredrick Institute of Plant Protection and Toxicology to conduct a study, which found that endosulfan was not harmful. Activists opposing use of the pesticide were threatened with legal action.

India is the largest manufacturer of endosulfan in the world. Three companies produce endosulfan in India - the largest is Excel Industries, the others are Hindustan Insecticide Limited and EID Parry.

Remediation of soil and water contaminated with endosulfan may soon be possible. Last February, scientists at the University of California, Riverside (UCR) announced that they have isolated microorganisms capable of degrading endosulfan.

Bioremediation of contaminated sites and water bodies by using these microbial strains will provide an environment free of endosulfan toxicity, the researchers indicate in their paper, published in the "Journal of Environmental Quality."

"We have been successful in isolating strains that can use endosulfan as a carbon and energy source," said William Frankenberger, director of the UCR Center for Technology Development and professor of soil science and soil microbiologist at the university.

The results of the study suggest that these microbial strains are a valuable source of enzymes that degrade endosulfan. They may be used for the detoxification of endosulfan in contaminated soils, wastedumps and water bodies, as well as agricultural dealership sites, waste water from recycling plants and unused or expired stockpiles of endosulfan.