Prenatal exposure to the pesticides chlorpyrifos and 2,4-Dichlorophenoxyacetic acid is associated with circulating levels of reproductive hormones in healthy infant girls

Background: Pesticides are widespread in the environment and suspected endocrine disruptors that may interfere with sex hormones. Following the chlorpyrifos ban in 2020, use of alternative pesticides has increased; 2,4-Dichlorophenoxyacetic acid (2,4-D) remains widely used. This study examined the association between maternal pesticide exposure and pituitary, gonadal, and adrenal hormones in offspring during infancy. Methods: We recruited pregnant women from 2010 to 2012 in the Odense Child Cohort, including 489 mother-child pairs. Maternal urinary concentrations of the generic pyrethroid metabolite 3-phenoxybenzoic acid (3-PBA), the chlorpyrifos metabolite 3,5,6-trichloro-2-pyridinol (TCPY), and the herbicide 2,4-D were measured at gestational week 28. Serum concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone (T), estrone (E1), estradiol (E2), 17-hydroxyprogesterone (17-OHP), Androstenedione (Adione), and Dehydroepiandrosterone sulfate (DHEAS) were assessed in infancy. Associations between prenatal pesticide exposure and offspring reproductive hormones (expressed as age- and sex-specific standard deviation (SD) scores) were assessed using multivariate linear regression. Results: In girls, higher maternal urinary TCPY and 2,4-D concentrations were associated with lower LH (-0.07 SD, 95 % CI: − 0.13; − 0.01 and − 0.06 SD, 95 % CI: − 0.11; − 0.02, per 1 µg/L increase, respectively); there were trends towards associations between 3-PBA, TCPY, 2,4-D and lower LH, FSH, E1 and E2, respectively. No associations were seen in boys. Conclusion: In this low-exposed cohort, prenatal exposure to chlorpyrifos and 2,4-D may affect the reproductive hormones in girls, but not boys, during minipuberty, which may have long-term implications. This is of public health concern given the fact that > 90 % of participants were exposed.