The organic chemical contamination of eels in the lower Thames in 2007

Juergens, Monika ORCID:; Johnson, Andrew ORCID:; Chaemfa, Chakra; Jones, Kevin; Hughes, David. 2009 The organic chemical contamination of eels in the lower Thames in 2007. Environment Agency, 19pp. (Unpublished)

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The Environment Agency provided samples from 35 eels caught in autumn of 2007 in the River Thames between Sunbury and Molesey (upstream of the tidal limit) and in the Thames estuary around Woolwich. These were analysed for 14 organochlorine pesticides and by-products and 41 PCB congeners, including the seven frequently detected congeners commonly used as indicators for PCB contamination (ICES7). Most of the investigated chemicals were detectable in every one of the samples although they have all been banned or severely restricted many years ago. However, based on the measured chemicals, all the analysed eels would be considered safe to eat. For most of the chemicals determined, the levels in eels from the Sunbury to Molesey stretch were lower than from the estuary eels, but this can be largely explained by an overall higher fat content of the estuary individuals. Compared to bleak and roach caught in the Thames in the same year, eels had generally higher contamination for all chemicals with regards to fresh weight but, as with the site difference, the values were similar for all species once normalized to lipid content. The ICES7 indicator PCBs and the pesticide lindane (gamma-HCH) as well as the DDT degradation product DDE have been chosen for comparison with past data as these substances have been relatively frequently reported in the literature. ICES7 PCB contamination levels were fairly typical for recent UK eel data but lower than a few of the UK eel samples from the 1990s, whereas DDE and lindane contamination was lower than in the very few other UK eel studies that reported these chemicals. Compared to a recent European survey, the PCB contamination found in the eels is this study was approximately in the lower third of values. Although by no means as highly contaminated with persistent organic pollutants as some of the eels from previous UK and European studies, the presence of so many of these chemicals, with their known health effects in the 2007 Thames eels, may be a matter of concern for these fish, though perhaps not as significant as other issues, such as parasites.

Item Type: Publication - Report
Programmes: CEH Topics & Objectives 2009 - 2012 > Water
UKCEH and CEH Sections/Science Areas: Acreman
Funders/Sponsors: Environment Agency, Thames Region
NORA Subject Terms: Ecology and Environment
Date made live: 13 Dec 2011 11:55 +0 (UTC)

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