Maternal exposure to biosolids reshapes chemical burden and steroidogenic pathways to promote adipogenic differentiation in a sheep model

Biosolids, a by-product of wastewater treatment, are widely used as agricultural fertilizers and contain anthropogenically-derived chemical mixtures, often including obesogens such as perfluoroalkyl substances (PFAS), bisphenols, and phthalates. Given the potential for endocrine and metabolic disruption of biosolids' complex chemical mixtures, we hypothesized that maternal exposure to biosolids-treated pastures would alter circulating chemical and steroid profiles and that these changes could influence adipogenic differentiation in preadipocytes. To test this, we characterized 125 environmental chemicals across 16 classes using ID-LC-MS/MS and adrenal- and ovarian-derived steroids using LC-MS/MS in plasma from pregnant sheep (n = 6/group) collected at gestational day 30. Biosolids exposure increased total concentrations of several chemical classes, notably phthalates, parabens, bisphenols, and PFAS. Steroid profiling revealed lower plasma pregnenolone and higher 17-OH-pregnenolone, DHEA, 17-OH-progesterone, and 18-OH-corticosterone. Adipogenic effects were assessed by differentiating 3T3-L1 preadipocytes in the presence of plasma. Plasma from biosolids-exposed females significantly increased 3T3-L1 lipid droplet count and BODIPY staining intensity compared to control plasma. No differences were observed between plasma from pregnancies with male vs. female fetuses. Lastly, LASSO regression revealed positive associations between acetamiprid and perfluorobutane sulfonic acid concentrations and lipid accumulation. In conclusion, exposure to biosolids-treated pastures altered chemical and steroid profiles in plasma from pregnant females and increased adipogenic differentiation in vitro, suggesting that circulating factors associated with environmental chemical mixtures may influence adipose development. These findings highlight the need to evaluate the safety of biosolids use and their potential contribution to metabolic risk.