This new research shows that farmers who used agricultural insecticides experienced increased neurological symptoms, even when they were no longer using products. Data from 18,782 North Carolina and Iowa farmers linked use of insecticides, including organophosphates and organochlorines, to reports of reoccurring headaches, fatigue, insomnia, dizziness, nausea, hand tremors, numbness and other neurological symptoms. Some of insecticides addressed by study are still on market, but some, including DDT, have been banned or restricted.

These findings will be available online in April, and published in June issue of Environmental Health Perspectives. The research is part of ongoing Agricultural Health Study funded by National Institute of Environmental Health Sciences and National Cancer Institute, two of National Institutes of Health, and Environmental Protection Agency.

"This research is really important because it evaluated health effects of agricultural chemicals as they were commonly used by farmers. It's different from previous studies that focused on pesticide poisoning or high dose exposures, for example when large amounts of a chemical were accidentally spilled on skin," said Freya Kamel, Ph.D., a researcher for National Institute of Environmental Health Sciences (NIEHS).

Researchers found that nearly 3,000 participants had a high lifetime exposure to insecticides--that is, they used insecticides more than 500 days in their lifetime. Nearly 800 of these farmers reported more than 10 neurological symptoms compared to those using insecticides fewer than 50 days. The researchers found no significant association between neurological symptoms and other chemicals, including herbicides or fungicides, and only a weak association between fumigant exposure and neurological symptoms.