Methylated hexachlorocyclohexane in blue mussels ( Mytilus edulis) from the Mersey and Dee Estuaries

Abstract

Blue mussels ( Mytilus edulis) from the Mersey and Dee Estuaries have been found to contain high concentrations of α-MHCH (methyl hexachlorocyclohexane) and γ-MHCH (methyl lindane), and a series of other methylated isomers of MHCH. Mean values for ΣMHCH in mussels declined serially from Rock Ferry (81.4 ± 19.3 μg kg −1), the innermost site in the Mersey Estuary, to Egremont (49.0 ± 8.6 μg kg −1) and New Brighton (11.1 ± 3.8 μg kg −1); but the value for Crosby (67.0 ± 10.2 μg kg −1) on the Liverpool shoreline was surprisingly high. Concentrations of α-HCH and γ-HCH in M. edulis were consistently low, at <3.0 μg kg −1. Comparisons between MHCH data for M. edulis and muscle tissue of both dab ( Limanda limanda) and plaice ( Pleuronectes platessa) give some evidence of food chain biomagnification of MHCH compounds, with adult plaice caught within the Mersey Estuary, where they feed on shellfish, showing very high levels of γ-MHCH (18 ± 9 μg kg −1) and MHCH (169 ± 76 μg kg −1). Methylated analogues of HCH in biota are of potential regulatory interest and of substantial importance to the environmental management of the Mersey and Dee Estuaries.