Environmental and Molecular Mutagenesis 50:404^412 (2009) Research Article Mutagenicity of an Aged Gasworks Soil During Bioslurry Treatment Christine L. Lemieux,1* Krista D. Lynes,1,2 Paul A. White,1 Staffan Lundstedt,3 Lars berg, 3 and Iain B. Lambert2 1Mechanistic Studies Division, Chemicals Management Directorate, Health Canada, Ottawa, Ontario, Canada 2Department of Biology, Carleton University, Ottawa, Ontario, Canada 3Department of Chemistry, Umea˚ University, Umea˚, Sweden This study investigated changes in the mutagenic activity of organic fractions from soil contaminated with polycyclic aromatic hydrocarbons (PAHs) dur- ing pilot-scale bioslurry remediation. Slurry sam- ples were previously analyzed for changes in PAH and polycyclic aromatic compound content, and this study examined the correspondence between the chemical and toxicological metrics. Nonpolar neutral and semipolar aromatic frac- tions of samples obtained on days 0, 3, 7, 24, and 29 of treatment were assayed for mutagenic- ity using the Salmonella mutation assay. Most samples elicited a signiﬁcant positive response on Salmonella strains TA98, YG1041, and YG1042 with and without S9 metabolic activation; how- ever, TA100 failed to detect mutagenicity in any sample. Changes in the mutagenic activity of the fractions across treatment time and metabolic acti- vation conditions suggests a pattern of formation and transformation of mutagenic compounds that may include a wide range of PAH derivatives such as aromatic amines, oxygenated PAHs, and S-heterocyclic compounds. The prior chemical analyses documented the formation of oxygenated PAHs during the treatment (e.g., 4-oxapyrene-5- one), and the mutagenicity analyses showed high corresponding activity in the semipolar fraction with and without metabolic activation. However, it could not be veriﬁed that these speciﬁc com- pounds were the underlying cause of the observed changes in mutagenic activity. The results high- light the need for concurrent chemical and toxico- logical proﬁling of contaminated sites undergoing remediation to ensure elimination of priority con- taminants as well as a reduction in toxicological hazard. Moreover, the results imply that remedia- tion efﬁcacy and utility be evaluated using both chemical and toxicological metrics. Environ. Mol. Mutagen. 50:404–412, 2009. VC 2009 Wiley-Liss, Inc.y Key words: bioremediation; polycyclic aromatic hydrocarbons; contaminated soil; mutagenicity INTRODUCTION The improper disposal of chemical wastes at industrial sites, such as manufactured gas plants (or gasworks), cok- ing operations, and wood preservation facilities, has resulted in the release of polycyclic aromatic hydrocar- bons (PAHs) and other polycyclic aromatic compounds (PACs). The discharged material often takes the form of coal tar or coal-tar creosote, highly complex materials containing hundreds of PAHs and PACs, including a vari- ety of mutagenic carcinogens [WHO, 2004]. Prior to the 1970s, few regulations existed to guide the safe disposal of this type of industrial waste. It was often dumped on or near the site, leaving a legacy of contamination at many sites that have since been abandoned. Soils conta- minated with complex PAH mixtures are increasingly recognized as constituting a health and environmental hazard, and their hazardous nature can impede the rede- VC 2009 Government of Canada. yExclusive worldwide publication rights in the article have been transferred to Wiley-Liss, Inc. velopment of valuable land for residential, commercial, and/or recreational use. PAHs and related PACs comprise a class of recalcitrant organic pollutants that are known to be toxic, mutagenic, Grant sponsors: Federal Contaminated Sites Action Plan, Canadian Reg- ulatory Strategy for Biotechnology, Natural Sciences and Engineering Research Council of Canada, Northern Sweden Soil Remediation Center (MCN). *Correspondence to: Christine L. Lemieux, Mechanistic Studies Divi- sion, Chemicals Management Directorate, Health Canada, 50 Colombine Dr., Tunney’s Pasture 0803A, Ottawa, ON, Canada K1A 0K9. E-mail: christine_lemieux@hc-sc.gc.ca Received 12 September 2008; provisionally accepted 9 December 2008; and in ﬁnal form 9 December 2008 DOI 10.1002/em.20473 Published online 9 March 2009 in Wiley InterScience (www.interscience. wiley.com).