Associations Between Heavy Metal Exposure from Milk and Steroid Hormones in Mothers

Environmental exposure to heavy metals is ubiquitous. However, its relationship with steroid hormone levels is not well understood, particularly in pregnant women. This study investigated the association between prenatal heavy metal exposure and steroid hormone levels in an e-waste disposal area in China. We analyzed the Cd, Cr, Mn, Pb, Cu, and As concentrations in 102 human milk samples collected 4 weeks after delivery. Multiple regression analysis was used to assess the associations and interactions between heavy metals and steroidal hormones. We found positive associations between Mn and estrone and estriol (estrone: β = 0.713, 95%CI = 0.046, 1.381 and estriol: β = 1.290, 95%CI = 0.494, 2.085) and between Cd and progesterone (β = 0.280; 95%CI = 0.053, 0.506). We observed negative associations between Cr and estrone and estriol (estrone: β = - 0.757, 95%CI = - 1.473, - 0.041 and estriol: β = - 1.354, 95%CI = - 2.209, - 0.499). At last, we found that Pb was negatively associated with estrone (estrone: β = - 0.537, 95%CI = - 1.053, - 0.020). Our results suggest that exposure to heavy metals may affect steroid hormone levels in mothers living in an e-waste recycling area in China.