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 the insecticides addressed by the study are still on the market, but some, including DDT, have been banned or restricted. "This research is really important because it evaluated the health effects of agricultural chemicals as they were commonly used by farmers. It is 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 the skin," said Freya Kamel, Ph.D., a researcher for the 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 ten 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.
"Because the participants in this study are telling us they have never been previously diagnosed with pesticide poisoning or medically treated for any exposure to any pesticide, we are led to conclude that their symptoms are related to moderate lifetime exposure," said Dr. Kamel.
"Most studies of this issue have sample sizes ranging from 50 to 100 participants, making it hard to understand the detailed relationship between exposure and health effects. The large size of this study gives it great statistical power," said Dr. Kamel.
MEDICA.de; Source: National Institute of Environmental Health Sciences