Chlorpyrifos in Fish and Seals from the Canadian Arctic

Abstract

Abstract Chlorpyrifos (CPY), a widely used organothiophosphate insecticide, has been proposed for listing on Annex A of the Stockholm Convention on Persistent Organic Pollutants. While CPY has been widely measured in Arctic air and seawater, information on bioaccumulation of CPY in aquatic food webs in the Arctic is very limited. This study presents results of additional monitoring data on CPY in fish and marine mammal samples from the Canadian Arctic/sub-Arctic based on ongoing studies under Canada’s Northern Contaminants Program. The majority of the CPY data was from samples collected from 2011 to 2021 and analysed using USEPA Method 1699, involving quantification by high resolution mass spectrometry. The available dataset showed low detection frequencies of CPY ranging from zero in arctic grayling (Thymallus arcticus) to 52% in arctic cod (Boreogadus saida). To enable statistical analysis the non-detects were substituted with ½ the detection limit (½ DL) based on the assumption that the non-detects were not zero and previous studies showing CPY was consistently detected in water and air in the Canadian Arctic. Largest geometric mean CPY concentrations were found in lake whitefish (Coregonus clupeaformis) muscle (0.56 ng/g wet wt) while burbot (Lota lota) liver had the highest maximum concentration (8.2 ng/g). Log10 CPY concentrations (with ½ DL substitution) were significantly correlated with % lipid and length in lake trout (Salvelinus namaycush) muscle and with % lipid in burbot liver. Geomean concentrations in ringed seal (Pusa hispida) blubber from 8 communities ranged from 0.005 to 0.605 ng/g and showed no geo-spatial trends. Overall, the results indicate widespread but very low level contamination of Arctic fish and seals by CPY.