Research Suggests Link between Autoimmune Disorders and Pesticides

The autoimmune diseases lupus and rheumatoid arthritis may be linked to using common household insecticides, say researchers from the National Institute of Environmental Health Sciences. Previous studies have found a connection between agricultural−grade pesticides and these two diseases – farmers appear to be at higher risk – but the current study is apparently the first to examine the connection in a smaller, residential setting.

Women who reported the highest level of contact with pesticides were at twice the risk for developing one of the two diseases compared those who contacted them the least.

Christine Parks and her team looked at data from almost 77,000 women between the ages of 50 and 79. The participants reported, among other things, the frequency with which they came into contact with various pesticides, which included ant, roach, mosquito, and termite killers, but excluded insect repellents.

Parks and her colleagues found that women who reported using or mixing pesticides tended to develop lupus or rheumatoid arthritis more frequently than those who did not. In fact, women who reported the highest level of contact with pesticides were at twice the risk for developing one of the two diseases compared those who contacted them the least.

However, the study has some shortcomings, and some questions remain unanswered. First, the research simply shows that there exists a correlation between pesticides and the diseases in question: it does not actually illustrate a cause−and−effect relationship. It’s possible that there is another, as−yet−unknown variable at play here – one which might increase certain women’s risk for autoimmune diseases, and help explain the insecticide−autoimmune connection observed in this study. Additionally, the exact type of chemicals the women used is unknown, and as Parks points out, insecticides have changed a lot over the years.

Parks says that more research will be needed to determine what mechanism might be behind the correlation observed here and in previous studies. In the meantime, she urges individuals to “read the labels and take precautions to minimize their personal exposure" to pesticides. "This is the case regardless of whether these results are implicating a chemical that's on the market now or was before."

The study was presented at the American College of Rheumatology’s annual meeting in Philadelphia on October 17, 2009.