Nationwide PCB congener pattern analysis in freshwater fish samples in France

Abstract

The 2006 european directive on polychlorodibenzodioxins and related compounds in foodstuffs prompted in France a nationwide monitoring study of freshwater fish contamination by these compounds. A database covering about 300 sites (2848 samples of 36 fish species) was obtained from this study. This database was used to explore congener pattern distributions, in order to identify typical sources and the impact of biotransformation on these sources. Fish ecological traits and fish size are the main factors explaining the overall PCB contamination in the two pre-identified categories of species (high or low propensity to accumulate hydrophobic compounds). Lipid content is also an influencing factor, but its relationship to other factors remains uncertain. Species show distinct congener patterns, related more to their physiology than to ecological traits. Spatial patterns were studied on selected sites having more than five individuals analysed – either chub (Squalius cephalus) or barbel (Barbus barbus), the most widespread species in the database –. We identified six patterns, which mainly differed in the respective proportions of congeners potentially biotransformed by fish. No connection to typical sources, e.g. technical mixtures, was identified. These patterns instead represent an ageing path of the initial mixtures; they could be used for setting remediation priorities.

Keywords

• PCB
• fish
• congener pattern
• statistics
• metabolism