Workers who apply certain pesticides to farm fields are twice as likely to contract melanoma, a deadly form of skin cancer, according to a new scientific study.

The findings add to evidence suggesting that frequent use of pesticides could raise the risk of melanoma. Rates of the disease have tripled in the United States in the last 30 years, with sun exposure identified as the major cause.

The researchers identified six pesticides that, with repeated exposure, doubled the risk of skin cancer among farmers and other workers who applied the chemicals to crops.

Four of the chemicals - maneb, mancozeb, methyl-parathion and carbaryl - are used in the United States on a variety of crops, including nuts, vegetables and fruits. Two others, benomyl and ethyl-parathion, were voluntarily cancelled by their manufacturers in 2008.

“Most previous melanoma literature has focused on host factors and sun exposure. Our research shows an association between several pesticides and melanoma, providing support for the hypothesis that agricultural chemicals may be another important source of melanoma risk,” according to the report by epidemiologists from University of Iowa, the National Institute of Environmental Health Sciences and National Cancer Institute.

The findings also may have implications for consumers who use pesticides in their homes or yards. Carbaryl, one of the pesticides linked to skin cancer, is the active ingredient in the insecticide Sevin, which is widely used by consumers to kill pests in gardens and lawns.

The study, published last month in the journal Environmental Health Perspectives, examined cancer rates in 56,285 pesticide applicators in Iowa and North Carolina as part of the federal government's Agricultural Health Study, a large, long-term study of pesticide applicators and their spouses.

The pesticide applicators were asked how often they were exposed to 50 pesticides. The researchers then compared their cancer rates, finding that those who were exposed to some of the chemicals had a higher risk of cutaneous melanoma then their peers who handled other chemicals.

A major weakness of the study is that there was no dosage data for the workers. Instead, the researchers approximated how much pesticide each person was exposed to by adding up the days they had been exposed and incorporating information they provided on how they applied the chemicals and what protective equipment they wore.

3 Comments

1. 1. bertwindon 03:47 PM 3/31/10

   "... may be another important source of melanoma .."
   I hope I am not alone when I say that I would much prefer "significant" to "important" here.

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2. 2. always thinking 04:26 PM 4/1/10

   I bet that the link has to do with inflammation - that the people exposed to the pesticides who developed melanoma showed greater skin reactivity to the pesticides or had other symptoms of inflammation related problems. I'd be interested in hearing whether or not levels of inflammation relative to pesticide exposure and development of melanoma were studied.

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3. 3. Jehnavi 12:57 AM 2/14/11

   Carbaryl, a pesticide linked to cancer identified in the study, was a pesticide active ingredient in popular home and garden Sevin, now annulled the United States for these applications.
   http://www.justcancer.org/skin-cancer.html

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