MONITORING OF MUTAGENICITY IN AQUATIC BIOTA AS A TECHNIQUE FOR THE ENVIRONMENTAL ASSESSMENT

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Mussels were harvested at 5 selected sites along the coast of Seto Inland Sea and their edible parts were extracted with acetone-acetonitrile. The extract was then subjected to blue rayon (BR) treatment and the sample thus prepared was analyzed for mutagenicity with Salmonella typhimurium YG1024 and for benzo(a)pyrene (BaP) with HPLC-Fl. Eight out of 49 mussel groups contained BaP more than 1.0 ng/g and 17 out of 29 group showed positive results, the number of revertants exceeded 3 times more than that of solvent control. A positive correlation was observed between the level of BaP and the mutagenicity in individual groups. Blue rayon was hunged for 24 hr in the sea water at the same sites where mussels were collected. The eluate with methanoammonia was condensed and also assayed mutagenicity and BaP content. The eluate from 1g equivalent BR contained 0.05 to 19.5 ng of BaP and 17 out of 29 samples showed positive results. Again a positive correlation was observed between the amount of BaP and the mutagenicity. In order to identify the attributable components to the mutagenicity, we fractionated sample extract from mussel and the eluate from BR through C18 column with HPLC and assayed mutagenicity in each fraction. In case of mussel, elevated mutagenicity was observed in the polar fraction than that contained BaP. Further Yamato-shijimi, Corbicula japonica, was experimentally exposed to BaP at 0.058-0.224 ng/ml in an aquarium. After 12 and 24 hr, an elevated mutagenicity was again observed in the polar fraction, however the bivalve accumulated merely 11-38 times higher level of BaP than that in the aquarium. The above results suggest that a monitoring of mutagenicity in biota samples will provide a potential approach to carcinogenic substances in the aquatic environment.