Ability of polycyclic aromatic hydrocarbons to induce 7-ethoxyresorufin-o-deethylase activity in a trout liver cell line

Along with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 24 unsubstituted pol ycyclic aromatic hydrocarbons (PAHs) were evaluated for their ability to in duce 7-ethoxyresorufin-o-deethylase (EROD) activity in the rainbow trout li ver cell, line RTL-W1. When the duration and cell density of exposure were increased, the EC50 for EROD induction was relatively constant for TCDD, bu t increased for PAHs. Regardless of exposure conditions, EROD activity was not induced by 9 PAHs: naphthalene, phenanthrene, anthracene, pyrene, peryl ene, acenaphthylene, acenaphthene, fluorene, and fluoranthene. Two PAHs, be nzo[g,h,i]perylene and coronene, induced EROD activity inconsistently. The remaining 13 PAHs consistently induced EROD activity. The EC(50)s for induc tion exhibited approximately a 110-fold range. The order of potency, from m ost to least potent, was benzo[k]fluoranthene, dibenzo[a,i]pyrene, dibenzo [a,h]anthracene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, benzo [b]fluoranth ene, pentacene, benzo[b]anthracene, benzo[b] fluorene, chrysene, benzo[a]an thracene, benzo[e]pyrene, and triphenylene. When the induction potency was expressed relative to TCDD, the toxic equivalency factors (TEFs) ranged fro m 0.001 to 0.000 01. When expressed relative to benzo[a]pyrene, the TEFs ra nged from 3.44 to 0.03. (C) 1999 Academic Press.