PCB and organochlorine pesticide burden in eels in the lower Thames river (UK)

Thirty-five European eels (Anguilla anguilla), caught in 2007 in the river Thames upstream and downstream of both London and the tidal limit, were analysed for PCBs and organochlorine pesticides. Most chemicals were detectable in every fish, although they have been banned or severely restricted for many years. In general, the tidal eels were more contaminated than upstream ones, which was related to their higher lipid contents. The ICES7 indicator PCB concentrations ranged overall from 4.2 to 124 µg/kg fresh weight with averages of 33 and 56 µg/kg for the upstream and tidal eels; 3.5-104 µg/kg, average 26 and 48 µg/kg of that were ICES6 PCBs. Total DDT was on average 16 µg/kg (1.7-38 µg/kg) upstream and 18 µg/kg (8.6-35 µg/kg) downstream with about half of that provided by pp’DDE. Lindane (gamma-HCH) was found at up to 2.8 µg/kg (averages 0.58 and 1.1 µg/kg upstream and downstream) and hexachlorobenzene (HCB) was on average 1.9 and 2.5 µg/kg in the two groups with a maximum of 6.4 µg/kg in each. Therefore all individuals passed the European Environmental Quality Standard (EQS) of 10 µg/Kg for HCB. PCB contamination was fairly typical for recent UK eel data, whilst DDE and lindane concentrations were lower than most previous UK eel studies, perhaps reflecting a downward trend. Although not as highly contaminated as some eels from previous UK and European studies, the presence of so many of these chemicals, with their known health effects may represent a stress for the fish or higher predators, such as birds.