A fine kettle of fish: marine fish consumption, endocrine disrupting chemicals and thyroid hormones in rural Newfoundland.

Endocrine disrupting chemicals (EDCs), found in the environment, can cause hypothyroidism, infertility, and neurodevelopmental deficits. EDCs can be transported long distances on water currents and can bioaccumulate in marine food webs. Two water currents around Newfoundland are suspected of transporting EDCs to adjacent marine ecosystems. Newfoundlanders may be exposed to EDCs through consumption of local seafood contaminated with EDCs. This study investigated EDC exposure in rural Newfoundland population by 1) testing local seafood species for the presence of EDCs, 2) determining the extent of local seafood consumption by surveying residents of two rural communities (Burin and New-Wes-Valley), 3) measuring serum thyroid hormones and plasma EDC concentrations in individuals who participated in the seafood consumption survey, and 4) exploring associations between seafood consumption, EDCs and thyroid hormones in participants. Liver samples from cod (Gadus morhua) and turbot (Scophthalmus maximus) showed the presence of polybrominated diphenyl ethers (PBDEs), which were commonly used as flame retardants. There were higher levels of PBDEs in fish samples from the west coast compared to those from the northeast coast of Newfoundland. Residents from the study communities consumed local cod more than any other species, and seafood consumption was higher in males than in females; and higher in older (> 50 years) than in younger (<50 years) participants. Increasing frequency of local cod consumption was positively associated with increasing PCB (-105, -118, -138, -170, -180 and ΣPCBs) and p,p’-DDE concentrations in participants. Therefore local cod consumption may be a source of exposure to these EDCs for rural Newfoundlanders. All participants had at least 11 EDCs present in their plasma; polychlorinated biphenyl (PCB), polybrominated biphenyl (PBB) and dichlorodiphenyldichloroethylene (p,p’-DDE) concentrations were higher in older participants, reflecting exposure to EDCs that have since been discontinued; while PBDEs were higher in younger participants which aligns with their recent production and use. Participants from Burin had higher levels of PCBs and p,p’-DDE (legacy contaminants from Labrador current) while NWV participants had higher levels of PBB-153 and PBDEs (novel contaminants from St. Lawrence River). In conclusion, there is evidence that the rural Newfoundland population is exposed to EDCs through local seafood consumption.