ELSEVIER Mutation Research 335 (1995) 275-283 Environmental Mutagenesis Genotoxicity of nicotine and cotinine in the bacterial luminescence test Sun Hee Yim, Shane S. Que Hee * Department of Environmental Health Sciences and UCLA Center for Occupational and Em'ironmental Health, UCLA School of Public Health, 10833 La Conte Avenue, Los Angeles, CA 90095, USA Received 20 April 1995; revised 12 June 1995; accepted 15 June 1995 Abstract Cotinine was positive in the absence of $9 in the bacterial luminescence genotoxicity test at 1.25 mg/ml (9-15 h incubation) and at 2.50 mg/ml (18-30 incubation hours) signifying potential mutagenicity and teratogenicity. In the presence of $9, cotinine was positive at 1.25 mg/ml after 9 incubation hours. In contrast, nicotine was not at any concentration or incubation time. Nicotine/cotinine mixtures were still positive at physiological concentrations, with potentiation relative to cotinine alone with and without $9. Standard additions of nicotine to other positive controls such as 2-aminoanthracene (2AA) (a mutagen causing point mutations on activation), phenol (a DNA intercalator), and N-methyl- N'-nitrosoguanidine (MNNG) (a direct-acting point mutagen) revealed a complex nicotine effect. Nicotine antagonized MNNG without $9, and potentiated MNNG with $9, 2AA with and without $9, and phenol without $9. Cotinine was not a very potent agent relative to the positive controls. Since cotinine has been considered an inactive biological monitoring marker of nicotine absorption in humans, the present results indicate that the many health effect correlations based on cotinine in urine, serum, saliva, and blood may involve more cause and effect than thought hitherto. 1. Introduction The reverse mutation assay involving Salmonella typhimurium indicates point (base pair substitution and/or frameshift) mutations only (Ames et al., 1973, 1975; McCann et al., 1975). The major utility of the test is as an acute screening assay for carcino- gens. Unfortunately, carcinogenic metals and organ- ics that intercalate DNA do not act through point mutations, and require other screening assays. There- * Corresponding author. fore a battery screening approach is necessary. The latter is also essential to account for differences between eukaryotes, prokaryotes, and higher mam- mals. Nevertheless there is need for a more general bacterial screening test than the Salmonella assay. A reverse-mutation assay based on attaining the biolu- minescent state, the Mutatox test, involves dark mu- tants of Vibrio fischeri strain NRRL-B-11177 (Wagner et al., 1989; Elmore and Fitzgerald, 1990; Kwan et al., 1990; Ho and Quinn, 1993; Johnson, 1993). This assay detects DNA intercalating agents, inhibitors of DNA synthesis, DNA cross-linking agents, and agents producing large DNA deletions 0165-1161/95/$09.50 © 1995 Elsevier Science B.V. All rights reserved SSDI 0165- 1161 (95)00031-3