Validation of biomarkers of marine pollution exposure in sand flathead using Aroclor 1254

Abstract

The Australian marine fish, sand flathead ( Platycephalus bassensis), were exposed to the polychlorinated biphenyl (PCB) mixture Aroclor 1254 by intraperitoneal injections of 10, 100. 200 and 400 mg/kg in corn oil. Cytochrome P450 content, ethoxycoumarin O-deethylase (ECOD), ethoxyresorufin O-deethylase (EROD) and uridine diphospho-glucuronosyltransferase (UDP-GT) activities were measured to quantify liver detoxication enzyme response. The type and amount of metabolised PCBs in the bile were quantified by gas chromatography/mass spectrometry. EROD activity increased in a dose-dependent manner. At the 400 mg/kg dose, EROD activity was 2.64 ± 0.34 nmol/min per g liver (0.07 ± 0.01 nmol/min per mg protein), approximately 5 times control levels ( P < 0.05). UDP-GT activity at 400 mg/kg was 63.99 ± 8.69 U/g liver (1.53 ± 0.29 U/mg protein), an increase of 75% above control levels. Protein content of the liver increased 1.5-fold to 41.25 ± 2.52 mg/g liver and cytochrome P450 content increased 1.8-fold to 6.82 ± 0.91 nmol/g liver. No differences with treatment were seen in ECOD activity. Metabolised PCBs excreted in the bile were hydroxylated and conjugated with glucuronic acid or sulphate, and the increases in production of biliary metabolites paralleled the increases in total liver EROD activity. These results indicate that EROD and UDP-GT activities and biliary metabolites are sensitive biomarkers of exposure and that sand flathead represents an appropriate fish for use in further biomonitoring work.