Occupational
Childhood and adolescent residential and farm pesticide exposures and inflammatory bowel disease incidence in a U.S. cohort of women Dazhe Chen* Dazhe Chen Jennifer M.P. Woo Christine G. Parks Kaitlyn G. Lawrence Katie M. O’Brien Robert S. Sandler Dale P. Sandler
Evidence suggests that the human gut microbiome is an important contributor to the pathogenesis of autoimmunity and is affected by early life environmental exposures. Pesticide exposures have been associated with altered gut microbiome in animals and some autoimmune diseases in humans, but no study has examined early-life pesticide exposures in relation to inflammatory bowel disease (IBD). We used data from the Sister Study (2003-2021) to examine self-reported residential and farm pesticide exposures during childhood or adolescence in relation to incident IBD diagnosis after study enrollment. We estimated Hazard Ratios (HR) and 95%CIs using Cox models, with age as the time scale, adjusting for race and ethnicity, attained education, smoking, and birth year. We identified 1,151 self-reported incident IBD cases among 49,263 participants without IBD at enrollment. IBD hazards were elevated among those whose childhood residence was regularly treated with pesticides (HR: 1.26, CI: 1.09, 1.45), including those who ever personally applied the pesticides (HR: 1.47, CI: 1.04, 2.08), compared to those who were never exposed during childhood. We also observed a positive association between IBD and exposure to broadcast pesticide sprays before 1975 (i.e., time of DDT ban) (≥6 times vs. never HR: 1.42, CI: 1.17, 1.74). Among participants who lived on a farm during childhood for ≥1 year (N=9,370), IBD hazards were higher among those who were in crop fields during pesticide application (HR: 1.58, CI: 1.04, 2.40) and who ever personally applied pesticides on crops (HR: 1.79, CI: 1.19, 2.68) or livestock (HR: 1.63, CI: 1.05, 2.54) during childhood or adolescence compared to those without the specified exposure. Results were similar for ulcerative colitis alone (N=945) and when using a stricter definition for IBD that incorporated IBD surgery and medication. Findings provide preliminary evidence on early-life pesticide exposure as a novel risk factor for IBD.