Polychlorinated dibenzo-p-dioxins and dibenzofurans detected in bivalve samples from the NOAA National Status and Trends Program

•Most bivalves have low dioxin and furan concentrations.•The TEQ for >90% of the samples are at or below the level for human health concerns.•The highest TEQ are found near highly populated industrialized locations.•High TEQ values occurred where other contaminants are also present at high concentrations. Bivalve samples from 142 sites were analyzed to determine the concentration and toxicity equivalents (TEQ) of dioxins and furans (D/F) as part of the NOAA National Status and Trends Program. The total concentration of 17 D/F ranged from not detected to 203pg/g wet weight of tissue. Octachlorinated dibenzo-p-dioxin, OCDD, had a concentration range from not detected to 189pg/g and a mean concentration of 8.65pg/g. OCDD was the dominant D/F compound detected and accounted for, on average, over 70% of the total D/F concentration. The TEQ (compared to 2,3,7,8-TCDD) ranged from 0.12 to 7.32pg TEQ/g. The TEQ for 39% of the bivalves analyzed were below 0.238pg TEQ/g. TEQ above human consumption advisory concentration of 1.2pg TEQ/g were found in 9.3% of the samples analyzed. TEQ for D/F indicate very limited human health concerns from consumption of bivalves at most of the locations sampled.