26 May 2008

Pesticides raising diabetes risk?

Using certain chlorinated pesticides puts a person at increased risk of developing type 2 diabetes, and the greater the exposure, the greater the risk.

Using certain chlorinated pesticides puts a person at increased risk of developing type 2 diabetes, and the greater the exposure, the greater the risk, researchers from the National Institutes of Health in the US report.

Although the link to type 2 diabetes have not been explored in South Africa, a case of organochlorine poisoning was recently reported at a school in Groblersdal in the Limpopo province.

A compound containing the organoclorine lindane was used to fumigate a building on the school property. The occupational therapist practicing in the venue was diagnosed with organochlorine poisoning, while students complained of symptoms.

In humans, lindane primarily affects the nervous system, liver and kidneys, and may be a carcinogen and/or endocrine disruptor.

The World Health Organization classifies lindane as "Moderately Hazardous," and its international trade is restricted and regulated under the Rotterdam Convention on Prior Informed Consent. It is presently banned in more than 50 countries, and is being considered for inclusion in the Stockholm Convention on persistent organic pollutants, which would ban its production and use worldwide.

Dr Johan Minnaar, who treated the patient, said that the pesticide was administered by a registered pest control company. "It is shocking how little knowledge people, and especially registered professionals, have on the dangers of pesticides and agricultural chemicals.

"In South Africa a campaign to create awareness of the dangers of agricultural chemicals is desperately needed," said Minnaar.

Researching link to diabetes
Researchers at the National Institutes of Health in the US studied more than 31 000 licensed pesticide applicators participating in the Agricultural Health Study. Licensed pesticide applicators use more potent formulations of the chemicals than are found in products sold for use in the home or garden, the researchers note.

Five years after enrolling in the study, 1 176 had developed type 2 diabetes. Among the 50 different pesticides the researchers looked at, half were chlorinated, and 7 of these were tied to an increased risk of type 2 diabetes. They are: aldrin, chlordane, heptachlor, dichlorvos, trichlorfon, alachlor, and cyanazine.

Risk was higher among study participants who had ever been exposed to any of these chemicals, and increased as cumulative days of lifetime exposure increased, the team reports in the American Journal of Epidemiology.

The strongest link between exposure to the seven chemicals and type 2 diabetes was seen among obese people, possibly, the researchers say, because people with more body fat may store more of the chemicals in their bodies.

Important clue for further research
"All of the seven are chlorinated compounds," study investigator Dr Freya Kamel of the National Institute of Environmental Health in Research Triangle Park, North Carolina noted in an interview. "We don't know yet what the implication of that is, but it can't be a coincidence. I think it's an important clue for future research."

The three organochlorine pesticides, aldrin, chlordane, and heptachlor, are no longer sold in the United States, she added, but because they accumulate in animal tissues they remain at detectable levels in individuals' bodies, as well as in some food products.

People should follow instructions when using any product containing pesticides, Kamel said. But the best way to avoid developing type 2 diabetes, she added, is to follow existing public health recommendations to maintain a healthy weight, exercise, and eat a balanced diet. – (Health24, Anne Harding/Reuters Health)

SOURCE: American Journal of Epidemiology, published online May 14, 2008.

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May 2008


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