Hexachlorobutadiene (HCBD) contamination in the Arctic environment: A review

Hexachlorobutadiene (HCBD) is a halogenated hydrocarbon that is primarily produced as an unintentional byproduct in the manufacture of chlorinated solvents. Similarities between HCBD and other persistent organic pollutants (POPs) led to its listing in 2015 for global regulation under the Stockholm Convention on POPs. HCBD's toxicity and propensity for long-range transport means there is special concern for its potential impacts on Arctic ecosystems. The present review comprehensively summarizes all available information of the occurrence of HCBD in the Arctic environment, including its atmospheric, terrestrial, freshwater and marine ecosystems and biota. Overall, reports of HCBD in Arctic environmental media are scarce. HCBD has been measured in Arctic air collected from monitoring stations in Finland and Canada, yet there is a dearth of data for other abiotic matrices (i.e. soils, sediments, glacier ice, freshwaters and seawater). Low HCBD concentrations have been measured in Arctic terrestrial and marine biota, which is consistent with laboratory studies that indicate that HCBD has the potential to bioaccumulate, but not to biomagnify. Available data for Arctic biota suggest that terrestrial birds and mammals and seabirds, have comparatively higher HCBD concentrations than fish and marine mammals, warranting additional research. Although spatial and temporal trends in HCBD concentrations in the Arctic are currently limited, future monitoring of HCBD in the Arctic will be important for assessing the impact of global regulations newly-imposed by the Stockholm Convention on POPs. Keywords: POPs, Air, Biota, Contaminants, Long-range transport, Review