Persistent Organic Pollutants in Human Breast Milk and Associations with Maternal Thyroid Hormone Homeostasis

Epidemiological studies have indicated the thyroid-disrupting effects of persistent organic pollutants (POPs). However, the associations of low-exposure POPs with thyroid hormones (THs) remain unclear. Here we aim to assess the associations of low exposure of POPs, including polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), and polybrominated dibenzo-p-dioxins and furans (PBDD/Fs), with THs (total L-thyroxine (TT4), total 3,3’,5-triiodo-L-thyronine (TT3), and total 3,3’,5’-triiodo-L-thyronine (TrT3)) measured in human breast milk. Ninety-nine breast milk samples were collected from the LUPE cohort (2015–2016, Bavaria, Germany). Fourteen PBDEs, 17 PCBs, and 5 PCDD/Fs had quantification rates of > 80%. Nonmonotonic associations were observed. In adjusted single-pollutant models: (1) TT4 was inversely associated with BDE-99, -154, and -196; (2) TT3 was inversely associated with BDE-47, -99, -100, -197, -203, -207, and OCDD; (3) T...