Childhood and adolescent residential and farm pesticide exposures and inflammatory bowel disease incidence in a U.S. cohort of women

There are few known risk factors for inflammatory bowel disease (IBD), an autoimmune disease characterized by chronic intestinal inflammation. Use of specific pesticides has been associated with higher incidence of IBD among pesticide applicators and their spouses, but no study has examined pesticide exposure in early life, a period where the human immune system undergoes rapid changes. We evaluated pesticide use during childhood and adolescence and incidence of IBD among US women enrolled in the Sister Study. Incident IBD diagnoses between enrollment (2003–2009) and 2021 were identified and validated with medication use and colectomy/colostomy surgery. We estimated hazard ratios (HR) and 95 % confidence intervals (CI) for the relationship of childhood/adolescent residential and farm pesticide exposures with IBD incidence using Cox models, accounting for age, race and ethnicity, education, smoking, and birth year. We identified 277 incident IBD cases among 48,382 eligible participants. IBD hazard was elevated among those whose childhood residence was regularly treated with pesticides, especially among those who ever personally applied pesticides (HR = 1.39, 95%CI: 0.65, 2.99). We observed a positive association between IBD and exposure to broadcast pesticide sprays before DDT was banned (>6 times vs. never HR = 1.56, 95%CI: 1.06, 2.31). Among participants who lived on a farm during childhood/adolescence for ≥1 year (N = 9162), IBD hazards were higher among those who were in crop fields during pesticide application (HR = 2.06, 95%CI: 0.94, 4.51) and who ever personally applied pesticides on crops (HR = 1.85, 95%CI: 0.81, 4.18) or livestock (HR = 2.58, 95%CI: 1.14, 5.83). Early-life pesticide exposure may be a novel risk factor for IBD. Practices that reduce pesticide exposure during early life may help reduce the burden of this disease. [Display omitted] •The human immune system is susceptible to environmental exposures in early life.•We studied early-life pesticide use and inflammatory bowel disease (IBD) in women.•IBD was linked to residential pesticide use