METHYLATED HEXACHLOROCYCLOHEXANE IN BLUE MUSSELS (MYTILUS-EDULIS) FROM THE MERSEY AND DEE ESTUARIES

Blue mussels (Mytilus edulis) from the Mersey and Dee Estuaries have b een found to contain high concentrations of alpha-MHCH (methyl hexachl orocyclohexane) and gamma-MHCH (Methyl lindane), and a series of other methylated isomers of MHCH. Mean values for Sigma MHCH in mussels dec lined serially from Rock Ferry (81.4 +/- 19.3 mu g kg(-1)), the innerm ost site in the Mersey Estuary, to Egremont (49.0 +/- 8.6 mu g kg(-1)) and New Brighton (11.1 +/- 3.8 mu g kg(-1)); but the value for Crosby (67.0 +/- 10.2 mu g kg(-1)) on the Liverpool shoreline was surprising ly high. Concentrations of alpha-HCH and gamma-HCH in M. edulis were c onsistently low, at < 3.0 mu g kg(-1). Comparisons between MHCH data f or M. edulis and muscle tissue of both dab (Limanda limanda) and plaic e (Pleuronectes platessa) give some evidence of food chain biomagnific ation of MHCH compounds, with adult plaice caught within the Mersey Es tuary, where they feed on shellfish, showing very high levels of gamma -MHCH (18.9 +/- 9 mu g kg(-1)) and MHCH (169 +/- 76 mu g kg(-1)). Meth ylated analogues of HCH in biota are of potential regulatory interest and of substantial importance to the environmental management of the M ersey and Dee Estuaries. (C) 1997 Elsevier Science Ltd.