Levels of organochlorine compounds in freshwater fish from Catalonia, N.E. Spain

Levels of organochlorine compounds (PCBs, DDTs, HCHs and Heptachlor epoxide) were measured in fish species inhabiting the rivers of Catalonia, one of the most agriculturally and industrially developed areas of Spain. Although no time-trends in contamination levels can be determined because of the absence of data, a clear geographical distribution pattern is observed, with higher levels of contamination occurring in the lower reaches of the rivers. The Rivers Ebro and Ter show the highest levels of organochlorine compounds (mainly PCBs and DDTs). Furthermore, high levels of PCBs were found in an area of the Pre-Pyrenean mountains, which could be explained by aerial transport. The PCBs and ppʹDDE were found to be widely distributed and were present in all the samples analysed. The other compounds analysed occurred in more than 79% of samples. Mean values ranged from 0.001 mg/Kg for α-HCH to 0.181 mg/Kg for the PCBs, wet weight basis, and 0.11 mg/Kg for α-HCH to 17.84 mg/Kg for the PCBs, lipid weight basis. Most observed levels fall within those recommended for human consumption, although heptachlor epoxide may exceed permitted levels in some areas. However, the threat to wildlife may be considerable due to biomagnification and, particularly, to sensitive species situated high in the food web, such as the otter (Lutra lutra).