Though this study doesn't exactly prove cause and effect, Parks went on to say, "We need to start thinking about what chemicals or other factors related to insecticide use could explain these findings."
This piece from WebMD on the study says:
The researchers used data from the Women's Health Initiative Observational Study of 76,861 postmenopausal, predominantly white women ages 50 to 79. Of the total, 178 of them had rheumatoid arthritis and 27 had lupus. An additional eight women had both disorders. As part of the study, the women were asked a number of questions relating to farming and insecticide use.
"Importantly, the relationships we observed were not explained by other factors that we considered, including farm history, age, race, ethnicity, socioeconomic factors such as education and occupation, smoking and other risk factors for disease," Parks says.
According to Parks, Studies show that as many as three-fourths of U.S. households have reported using insecticides in the home or garden, and 20% of households have applied insecticides within the last month.
Darcy Majka, MD, assistant professor of medicine at Northwestern University Feinberg School of Medicine, analyzed the data from the study. "The findings are fairly compelling because they show the greater and longer the exposure, the greater the risk," Majka stated. She went on to ask, "Now we have to go back to the bench. Which products pose a risk? Is skin exposure [to blame], or inhaling?" She advises people to follow the directions on these products and to try take other measures to limit their exposure to chemicals.
For healthier lawn care solutions, read this article: Stop spraying chemicals on our lawns and use these sustainable solutions instead.