[Great Lakes Echo] The St. Lawrence River flows from Lake Ontario along the U.S.-Canada border, eventually draining into the Gulf of Saint Lawrence in the Atlantic Ocean. The largest estuary in the world is the destination for persistent chemicals that runoff from cities along the river’s path, ending up in the bodies of whales. Although attempts have been made for years to protect this population, Canadian researchers recently discovered levels of polybrominated diphenyl ethers (PBDE) flame retardants in the blubber of local beluga whales have not decreased, despite an implemented ban 17 years ago.

St. Lawrence belugas have a high death rate for calves and reproductive-age females and are listed as endangered by the federal agency Fisheries and Oceans Canada. Elevated PBDE levels, which may disturb the mammal’s hormone system, have recently been detected in human umbilical blood and have been linked to an increased risk of thyroid cancer.

The study, published in the July 2017 issue of Environmental Research, is an attempt to understand why the beluga population is not recovering after years of protection. Evidence suggests attempts to regulate PBDE contamination are too recent to have a clear impact on the population and on the estuary as a whole. (Because St. Lawrence belugas are residents of the estuary, their contamination levels can indicate contamination of the body of water.) PBDEs have been detected in the ocean at depths of 7,000-10,000 meters below sea level and as far away from cities as the Arctic Ocean.

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