Estimating polybrominated diphenyl ether (PBDE) exposure through seafood consumption in Switzerland using international food trade data

Seafood is a major source of human exposure to polybrominated diphenyl ethers (PBDEs). The intake of these globally distributed and bioaccumulative contaminants depends on both consumption patterns (which seafoods are consumed) and on their origins. Here, we investigate exposure to PBDEs through seafood consumption as a function of species, origins and consumption levels. We estimate the contribution of seafood consumption to PBDE exposures in the Swiss population using two approaches. The first approach estimates exposures by estimating the composition of the Swiss seafood diet using trade data and national statistics on total seafood consumption. This naive approach could be used for any country for which no individually reported consumption data are available for a population. The second approach uses dietary survey data provided by the Swiss Federal Statistical Office as part of the menuCH study for exposure estimates. To support region- and species-specific estimates of exposures for both approaches, we built a database of PBDE concentrations in seafood by analysis of published PBDE levels in fish from food markets or freshwater resources from various countries. We find estimated PBDE exposures ranging from 0.15 to 0.65 ng/kg bw/day for the trade data-based diet. These were close to the median exposures of 0.68 ng/kg bw/day for the Swiss population based on the menuCH survey, indicating that the composition and consumption rate derived from trade data are appropriate for calculating exposures in the average adult population. However, it could not account for PBDE exposures of more vulnerable (high seafood consuming) populations captured only by the survey data. All estimates were lower than the PBDE Chronic Oral Reference Doses (RfD's) suggested by the EPA, but could increase substantially to a value of 7 ng/kg bw/day if fish are sourced from the most contaminated origins, as in the case of Vietnamese shrimp/prawn, Norwegian salmon, and Swiss whitefish. Exposures as high as 8.50 ng/kg bw/day are estimated for the survey-based diet, which better captures the variability in consumption by individuals, including extreme high and low values. In general, the most frequently consumed species reported by Swiss consumers are consistent with those predicted using trade data.