Survey design for quantifying perfluoroalkyl acid concentrations in fish, prawns and crabs to assess human health...

Per and polyfluoroalkyl substances (PFASs) are emerging contaminants that have potential implications for human health. Perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) are perfluoroalkyl acids (PFAAs) that commonly bioaccumulate in aquatic species exposed to PFAS contaminant sources. Sampling programs aimed at measuring PFAA concentrations in free ranging aquatic animals to assess human health risk are not yet supported by any quantitative analyses to refine sampling effort required to provide a reasonable estimate of summary statistics for a species in a particular area. Here, an extensive, multi-species PFOS and PFHxS data set measured in free-ranging fish and crustaceans is employed to examine the effect of sample size on summary statistics estimated from sample data which are commonly employed in dietary exposure assessments. A unifying, cross-species model suggested that sample sizes between 20 and 40 individuals per species per location should provide a reasonable estimate of mean PFOS concentrations in free-ranging fish or crustaceans, but slightly larger sample sizes (30-50 individuals) may be required if sample medians are to be used in dietary exposure assessments. PFHxS concentrations were highly variable, so larger sample sizes should also be considered if this contaminant is of interest. The results are discussed in light of the levels of sampling effort reported in recent manuscripts, and other important considerations for designing sampling programs.