Associations between brominated flame retardants in human milk and thyroid-stimulating hormone (TSH) in neonates

Brominated flame retardants (BFRs) have been in widespread use in a vast array of consumer products since the 1970s. The metabolites of some BFRs show a structural similarity to thyroid hormones and experimental animal studies have confirmed that they may interfere with thyroid hormone homeostasis. A major concern has been whether intrauterine exposure to BFRs may disturb thyroid homeostasis since the foetal brain is particularly susceptible to alterations in thyroid hormones. However, few reports on newborns have been published to date. This study evaluated the association between BFRs and neonatal TSH (TSH). Six polybrominated di-Ph ethers (PBDEs) were measured in milk samples from 239 women who were part of the “Norwegian Human Milk Study” (HUMIS), 2003-2006. Hexabromocyclododecane (HBCD) and BDE-209 were measured in a subset of the women (193 and 46 milk samples, respectively). The milk was sampled at a median of 33 days after delivery. TSH was measured in babies three days after delivery as part of the routine national screening program for early detection of congenital hypothyroidism. Additional information was obtained through the Medical Birth Registry and questionnaires to the mothers. The PBDE concentrations in human milk in Norway were comparable to concentrations reported from other European countries and Asia, but not the US and Canada where levels are approximately one order of higher magnitude. The authors observed no statistically significant associations between BDE-47, 99, 153, 154, 209 and HBCD in human milk and TSH in models adjusted for possible confounders and other environmental toxicants including polychlorinated biphenyls (PCBs). The authors concluded that no association was observed between TSH and exposure to HBCD and PBDEs within the exposure levels.

Authors: Eggesbo, Merete; Thomsen, Cathrine; Jorgensen, Jens V.; Becher, Georg; Oyvind Odland, Jon; Longnecker, Matthew P. ;Full Source: Environmental Research 2011, 111(6), 737-743 (Eng) ;