Correlation of CYP1A1 induction, as measured by the P450 RGS biomarker assay, with high molecular weight PAHs in mussels deployed at various sites inSan Diego Bay in 1993 and 1995

In 1993 collections of marine mussels (Mytilus galloprovincialis) were depl oyed 1 m from the water surface at six sites in San Diego Bay for 88 days. A similar mussel deployment was conducted in 1995, except the animals were deployed 1 m off the bottom and only for 32 days. After recovery from the s ites, tissue was extracted with dichloromethane and the solvent extracts an alyzed for chemical contaminant content and the ability to produce CYP1A1 i nduction in a transgenic cell line (TV101L cells). The cells used in the as say (P450 RGS) are stably transfected with a plasmid containing firefly luc iferase linked to human CYP1A1 promoter sequences. Induction (fold increase compared to control) was determined by luminometry 16 h after application of small volumes (2-10 mu l) of solvent extracts to cultured cells. Small m ussels deployed in the Naval Station (NAV) in 1993 exhibited very high bioa ccumulation of polycyclic aromatic hydrocarbons (PAHs; 52 mu g/g) and polyc hlorinated biphenyls (PCBs), in addition to very strong induction of CYP1A1 measured by reporter gene system (RGS) responses. Large mussels deployed a t the NAV station in 1993 and intermediate-sized animals placed at three st ations within the NAV station in 1995 accumulated 13-29 mu g PAH/g and exhi bited relatively high RGS responses. Correlation of RGS responses for all m ussel samples to the measured PAH concentrations was 0.85 (r(2)). When the concentrations of seven specific PAHs found in the samples are converted to benzo[a]pyrene equivalents, from previously derived toxic equivalency fact ors (TEFs) for this test system, and compared to measured RGS responses, th e correlations are approximately 0.9. The results of these studies indicate that the RGS biomarker can be used as a screening tool for detection of CY P1A1-inducing compounds in tissues, and an estimate of potential human heal th or ecological risk from ingestion of contaminated organisms. Positive RG S responses can be followed by detailed chemical analyses of PAHs and copla nar PCBs using the same extract. (C) 1999 Elsevier Science Ltd. All rights reserved.