A new study has found a possible association between home exposure to  insecticides and two  autoimmune disorders.  According to a report on WebMD.com, the study was conducted by researchers at the National Institute of Environmental Health Sciences in Research Triangle Park, N.C., and presented at the annual meeting of the American College of Rheumatology.

One of the study authors told WebMD.com that insecticides are used in about 3/4 of all homes, and that such products were used in 20 percent of all homes in the past month.  This type of exposure can be “quite persistent” because pesticides don’t break down in homes.

Although the study doesn’t prove cause and effect, the researches said that it illustrated a “need to start thinking about what chemicals or other factors related to insecticide use” could explain the findings.

The researchers found that women who used insecticides six or more times a year had nearly two-and-a-half times the risk of developing rheumatoid arthritis (RA) or lupus than those who did not use bug sprays.  The risk more than doubled among women who had used insecticides for more than 20 years, WebMD.com said.  The study also found that hiring a gardener or commercial company to apply insecticides also doubles risks if they were used long-term. However, a history of working or living on a farm did not appear to increase risk of RA or lupus in the study.

The study used data from the Women’s Health Initiative Observational Study of 76,861 postmenopausal, predominantly white women ages 50 to 79.  Out of that group, 178 had RA, 27 had lupus an eight had both.  The women were surveyed about farming  and insecticide use, WebMD said.