DNA adducts in northern pike (Esox lucius) exposed to benzo[a]pyrene, benzo[k]flouranthene and 7H-dibenzo[c,g]carbazole

Formation and persistence of DNA adducts in liver, intestine, gills and brain of juvenile northern pike (Esox lucius) were analysed by 32P-postlabelling, following repeated oral exposure to benzo[a]pyrene (BaP), benzo[k]fluoranthene and 7H-Dibenzo[c,g]carbazole, singly or in a mixture. A complex pattern of adducts was detected in all examined tissues from fish treated with the mixture. Total adduct levels were highest in intestine, followed by liver, gills and brain. A major BaP-adduct made up approximately 50% of the total amount of adducts in the brain. Corresponding values in liver, intestine and gills were 23, 31 and 34%, respectively. Total adduct level in the intestine had declined to 29.4% of the maximum value 78 days after the last exposure, while there was no significant decline in adduct levels in liver, gills or brain. The results suggest that intestine is more susceptible to adduct formation than liver after oral exposure, and that adduct levels in the intestine represent ongoing or relative recent exposure.