title: Characterization of the H4IIE rat hepatoma cell bioassay for evaluation of environmental samples containing polynuclear aromatic hydrocarbons (PAHs).
abstract: The H4IIE rat hepatoma cell bioassay has been extensively used to assess the toxic equivalents (TEQs) of complex mixtures of halogenated aromatic hydrocarbons in environmental samples. However, there is often a discrepancy between bioassay induction results and toxic equivalents calculated from chemical analysis of samples; the former generally yield higher bioassay-TEQs. Polynuclear aromatic hydrocarbons (PAHs) are a class of chemicals which can significantly contribute to induction-TEQs. Benzo(a)pyrene (BAP), dibenz(a, h)anthracene (DBA), benz(a)anthracene (BA), benzo(k)fluoranthene (BkF), benzo(b)fluoranthene (BbF), chrysene (Chr), and indeno(1,2,3-c,d) pyrene (IdP) are carcinogenic PAHs found in environmental samples, including oysters collected from Galveston Bay. The induction potency of these PAHs relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was determined individually in rat hepatoma H4IIE cells seeded in 6-well plates, and the induction-derived equivalency factors (EFs) relative to TCDD were 0. 000354, 0.00203, 0.000025, 0.00478, 0.00253, 0.00020, 0.0011 for BAP, DBA, BA, BkF, BbF, Chr, and IdP, respectively. Dilutions of a reconstituted PAH mixture containing 23 PAHs (744 to 4466 ng/g total PAHs) with constant percentages of BAP (4.5%), DBA (3.5%), BA (2.4%), BkF (3.7%), BbF (3.5%), Chr (4.7%), and IdP (4.2%) yielded bioassay-derived induction-EQs that ranged from 0.52 to 1.44 ng/g. Oysters exposed in the laboratory to the same PAH mixture for 30 days differentially accumulated the PAHs with time. Bioassay-EQs for these oyster extracts ranged from 0.94 to 5.79 ng/g. These results were similar to the chemically calculated EQs which varied from 0.81 to 3.13 ng/g.
authors.affiliation: Veterinary Pharmacology and Physiology, Texas A&M University, College Station, Texas 77843-4466, USA.
authors.forename: K L
authors.initials: KL
authors.lastname: Willett
authors.forename: P R
authors.initials: PR
authors.lastname: Gardinali
authors.forename: J L
authors.initials: JL
authors.lastname: Sericano
authors.forename: T L
authors.initials: TL
authors.lastname: Wade
authors.forename: S H
authors.initials: SH
authors.lastname: Safe
mesh_terms: D000818:Animals; D001681:Biological Assay; D002273:Carcinogens / Q000737:chemistry / Q000633:toxicity*; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism; D004785:Environmental Pollutants / Q000633:toxicity*; D004790:Enzyme Induction; D008099:Liver / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D010125:Ostreidae / Q000187:drug effects / Q000378:metabolism; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry / Q000633:toxicity*; D051381:Rats
chemical_list: D002273:Carcinogens; D004785:Environmental Pollutants; D011084:Polycyclic Aromatic Hydrocarbons; D019363:Cytochrome P-450 CYP1A1