Polybrominated diphenyl ethers (PBDEs) are chemical flame retardants used in furniture foams, certain textiles and many plastics. In Vancouver, PBDE levels in human breast milk increased by about 15 fold from 1992 to 2002, bringing current levels to among the highest reported in the world. While the human health effects from ambient PBDE exposure are unknown, animal and laboratory studies indicate that PBDEs alter the levels and transport of thyroid hormones. This is of particular concern during pregnancy, when thyroid hormones play a critical role in fetal brain development. Because even small changes in maternal thyroid hormone levels in early pregnancy have been linked to neurological deficits in children, the thyroid disrupting potential of PBDEs is of interest for public health. Glenys Webster’s study is examining the relationships between PBDEs and thyroid hormones in 150 pregnant women in Vancouver. Using blood tests, her work will determine whether PDBEs are associated with altered thyroid hormone levels at different stages of pregnancy. A detailed questionnaire will also be used to identify the main sources of maternal exposure to PBDEs. Ultimately, Glenys’ research may lay the foundation for future investigations of PBDEs, other environmental toxins and neurological development in children in Vancouver.