07
Aug
Rheumatoid Arthritis Rates Elevated by Pesticide Exposure, Women Disproportionately Affected
(Beyond Pesticides, August 7, 2025) The novel study published in Arthritis & Rheumatology is the largest investigation of rheumatoid arthritis (RA) in women to date, finding evidence of heightened risks when exposed to insecticides through data collected from over 400 eligible women in the Agricultural Health Study (AHS). AHS participants include a cohort of thousands of licensed pesticide applicators and their spouses from Iowa and North Carolina, with this particular study as the first to consider the link between pesticide exposure and RA as it affects women’s health. Â
“Growing evidence suggests farming and agricultural pesticide use may be associated with rheumatoid arthritis (RA), but few studies have examined specific pesticides and RA among farm women, who may personally use pesticides or be indirectly exposed,†the study authors explain. The findings reveal that organochlorine insecticides that continue to persist in the environment, as well as organophosphate and synthetic pyrethroid pesticides used in public health or residential settings, correlate with RA diagnoses in women.Â
As shared in previous Daily News, for the most part organochlorine pesticides, including dichlorodiphenyltrichloroethane (DDT), are no longer used worldwide, but the legacy of their poisoning and contamination persists. These compounds are primarily made up of chlorine atoms, classified as persistent organic pollutants (POPs) due to their toxic longevity in the environment. Although many countries ban most organochlorine compounds, the chemicals remain in soils, water (solid and liquid), and the surrounding air at levels exceeding U.S. Environmental Protection Agency (EPA) standards. While EPA has ended pesticide registration for virtually all of the original POPs, the United States has not joined over 150 countries in ratifying a 2001 United Nations treaty known as the Stockholm Convention on Persistent Organic Pollutants, which requires the elimination of POPs’ production, use, and/or release.Â
Of the participants in the current study who report using pesticides, “[p]ersonal use of organochlorine insecticides was associated with incident RA, especially DDT and lindane,†the researchers say. Regarding organophosphate insecticides, a weaker association is seen apart from coumaphos and malathion. For carbamate insecticides, carbofuran use is associated with RA, as is the use of synthetic pyrethroid insecticides like permethrin and fungicides including captan and metalaxyl. Of the women who do not report personal use of pesticides, RA is associated with their spouses’ use of carbaryl, metribuzin, and maneb/mancozeb. Increased risks are also noted for indirect exposure to DDT, toxaphene, coumaphos, captan, metalaxyl, and malathion.Â
Rheumatoid arthritis, one of many types of arthritis, is classified as a systemic autoimmune disease that causes joint inflammation and pain. The disease involves both genetic and environmental risk factors, with many factors and triggers still unknown. According to the Arthritis Foundation, 1.5 million people in the U.S. have rheumatoid arthritis, with women three times more likely than men to develop the disease. A study by the Centers for Disease Control‘s (CDC) National Center for Health Statistics finds that the percentage of adults with arthritis increases in nonmetropolitan areas when compared to metropolitan areas, highlighting the potential role of agriculture and environmental contaminants.Â
Additional research (see here and here) suggests that, “RA may be associated with farming and pesticide use, but less is known about risks for women living on farms and the role of specific pesticides is not well understood.†With women already more likely to develop RA, exposure to environmental contaminants, such as pesticides, exacerbates the risks.Â
In the current study, the researchers review 410 cases of RA reported in women within the AHS cohort. The diagnoses were identified by self-reporting and then confirmed through validation, medication, and/or Medicare claims data. “We examined incident RA and personal pesticide use (including overall type, classes, and 32 specific pesticides), considering correlated pesticides and farming tasks, and explored associations with potential indirect exposures through applicator use among women who did not personally apply specific pesticides,†the authors state.Â
In assessing farming activities, the study also finds RA is associated with several other chemicals used in chemical-intensive agriculture, including but not limited to cleaning with solvents, grinding feed, applying fertilizers, and planting. “The AHS offers a unique opportunity to investigate RA risk in relation to specific pesticide types,†the researchers note. They continue, “With nearly 10 additional years of follow-up and more than 3-times as many cases than previous AHS reports on RA in spouses, this study of incident RA provides robust evidence that some insecticides may increase RA risk among women.â€Â Â
These results add to a growing body of science that suggests both direct and indirect exposure to pesticides can increase the risk of RA in women. (See here and here.) Studies show that pesticides can impact the development of RA through multiple pathways that are both direct (immunotoxic) or indirect (neuroendocrine, microbiome). As the authors state, “Pathogenesis [how the disease develops] of RA includes several pathways by which pesticide immune effects may play a role, including antigen citrullination and presentation, autoantibodies production, dysregulated innate and adaptive immune function, and local and systemic inflammation.â€Â
Previous research shows that DDT contributes to inflammation and decreases the body’s response to infection, as well as the immunosuppressive effects of malathion and lindane. The triazine herbicide metribuzin also has reported toxicity for endocrine and hepatic effects, in addition to impacts on neurological and immune pathways.Â
“Several pesticides associated with RA in this study have been associated with other diseases indicative of immune dysregulation among AHS spouses, including maneb/mancozeb and metalaxyl with hypo- or hyperthyroid diagnoses (mostly autoimmune, i.e., Grave’s or Hashimoto’s disease), and malathion, permethrin/pyrethroids, and metribuzin (asthma),†the researchers report. (See more information on immune system disorders and autoimmune diseases here and here.)Â
In finding a greater RA risk in females, this suggests a role of both endogenous (internal) and exogenous (external) hormonal exposures and pathways. Research shows that insecticides, including the organochlorines DDT and lindane and the organophosphates carbofuran and malathion, can impact hormone receptors and affect female reproductive function. Similar findings to the current study, from the Women’s Health Initiative Observational Study, also highlight the connection between insecticides and a heightened risk of RA, particularly among post-menopausal women who lived or worked on farms.Â
Previous Beyond Pesticides Daily News coverage, titled Exposure to Widely Used Bug Sprays Linked to Rheumatoid Arthritis, shows that exposure to widely used synthetic pyrethroids, present in many mosquito adulticides and household insecticides like RAID, is associated with a diagnosis of rheumatoid arthritis, according to research published in Environmental Science and Pollution Research. Â
The same pyrethroid metabolite was later found to be associated with increased osteoarthritis risk among U.S. adults, as shared in the Daily News Popular Pyrethroid Insecticides, Already Linked to Rheumatoid Arthritis, Associated with Osteoarthritis. In detecting levels of harmful compounds within the body, and connecting the high concentrations to diseases like arthritis, this study is one of many whose findings suggest the importance of an organic diet.Â
While certain diseases like arthritis have no cure, adopting an organic diet can eliminate exposure to toxic chemicals that increase disease risk. Studies show that switching to an organic diet can reduce pesticide levels in urine within just two weeks, and that organic agricultural practices and maintaining an organic diet reveal evidence of reduced concentrations of metabolites and lower body burden.Â
Beyond Pesticides urges farmers to embrace regenerative organic practices and for consumers to support this holistic, systems-based approach to land management by buying organic products (even on a budget!) or growing organic food. Learn more about the health benefits of organic agriculture here, and stay engaged by signing up to receive Action of the Week and Weekly News Updates delivered straight to your inbox here.Â
All unattributed positions and opinions in this piece are those of Beyond Pesticides. Â
Source:Â
Parks, C. et al. (2025) Associations of specific pesticides and incident rheumatoid arthritis among female spouses in the Agricultural Health Study, Arthritis & Rheumatology. Available at: https://acrjournals.onlinelibrary.wiley.com/doi/10.1002/art.43318.Â
