Pesticides and Hypospadias in Southern Brazil: An Ecological Study

Rio Grande do Sul ranks among the Brazilian states with the highest pesticide consumption and one of the highest prevalences of hypospadias, a congenital anomaly often associated with prenatal exposure to endocrine-disrupting chemicals. We assessed the relationship between prenatal pesticide exposure and hypospadias risk through an ecological study of 1 776 670 live births in the state from 2010 to 2022. Using a spatial Bayesian hierarchical model, we examined associations between hypospadias and municipal-level indicators: relative crop area, pesticide sales, and probability of pesticide detection in water samples. The prevalence was 4.69 cases per 10 000 live births, with 10 municipalities at high risk and 15 at low risk. Higher risk was associated with tobacco cultivation. Sales of metaflumizone and Melaleuca alternifolia were associated with increased risk, while detection probabilities of alachlor and DDT showed the largest estimated effects, although these estimates were accompanied by substantial uncertainty. While causal inference is not possible in this ecological design, findings generate hypotheses for future research on prenatal pesticide exposure. Considering other environmental risk factors may further clarify hypospadias etiology. Identifying modifiable determinants is key to guiding interventions and public policies to reduce this condition's burden, particularly in rural areas and agricultural populations.