Wood-preserving Waste Research Articles

Genotoxicity Assessment of Wood-Preserving Waste–Contaminated Soil Undergoing Bioremediation

ABSTRACT Bioremediation represents one of the most cost-effective technologies for treatment of petroleum hydrocarbons in contaminated surface soils. A major concern for regulatory agencies when evaluating bioremediation is how to determine acceptable levels for residual organics in soil. Although guidelines have been developed for some organics in soil, limited information is available to define acceptable levels of the metabolites of biological degradation. The products of oxidative degradation are likely to be more water soluble and may also be more toxic. The purpose of the current study was to monitor changes in compound concentration and genotoxicity in soils undergoing bioremediation. The site selected for this study was a former wood-preserving site in the northwestern United States. Soil samples were collected over a 4-year period from two 6075-m2 land treatment units. Conditions for biodegradation were enhanced by the addition of water and nutrients, as well as by frequent tilling to add oxygen. Due to the location of the facility, the temperature was conducive to a more rapid rate of biodegradation for approximately 6 months per year. Soil samples were collected using a grid system and solvent extracted. Polycyclic aromatic hydrocarbons were quantified in soil extracts using gas chromatography–mass spectrometry (GC/MS), and genotoxicity measured using the Salmonella/microsome assay. After 2 years of treatment, concentrations of total and carcinogenic polycyclic aromatic hydrocarbons (PAHs) were reduced to approximately 10% the concentration in the untreated soil. However, the mean weighted activity of the untreated soil was 293 net revertants per g soil, whereas the extracts of soil collected after 2 years induced a mean weighted activity of 325 net revertants per g soil. Thus, although biodegradation clearly reduced the concentration of total and carcinogenic PAHs in the surface soils, the results from the genotoxicity bioassay indicate that there was a lag in the reduction of mutagenicity in treated soils.

A Comparison of Two Methods for Fractionating Complex Mixtures in Preparation for Toxicity Analysis

Chemical fractionation is a widely used tool for the chemical and toxicological characterization of complex mixtures. The objective of this research was to compare two frequently employed methods for fractionating a wood preserving waste (WPW) containing polycyclic aromatic hydrocarbons (PAHs) and pentachlorophenol (PCP). The first method involved fractionation of the WPW into acid, base, and neutral fractions using a liquid-liquid acid/base/neutral (A/B/N) technique. The second method utilized alumina column chromatography to produce two fractions, A1 and A2. Gas chromatography and mass spectrometry were used to quantify the chemical components in all fractions. The alumina method recovered 473,338 mg of total PAHs (tPAHs) per kilogram crude, while the A/B/N method yielded only 193,379 mg tPAHs/kg crude. In contrast, the A/B/N method recovered 13.7 mg PCP/kg crude while the alumina method yielded only 0.5 mg PCP/kg crude. Three bioassays were used to determine the toxicity of the crude extract and fractions. The neutral and A1 fractions contained the highest levels of tPAHs and benzo[a]pyrene (BaP) but failed to induce a positive response in the Salmonella/microsome assay with concentrations containing as much as 1800 and 2500 ng BaP/plate, respectively. In the Escherichia coli prophage induction assay, the acid fraction, which contained 472 mg PCP/kg fraction, induced a positive response, as did the base fraction, which did not contain detectable PCP. Significant reduction of gap junctional intercellular communication in hepatic cells occurred with the crude extract and acid, base, and neutral fractions. Overall, the results of these bioassays suggest that PCP genotoxicity was expressed in the acid fraction, whereas the cumulative genotoxicity of genotoxic PAHs appeared to be masked in the isolates from either fractionation method. The optimal fractionation method for a mixture of chlorophenols and PAHs may involve a refined hybrid method.

Comparative 32P‐postlabeling analysis of exogenous and endogenous DNA adducts in mouse skin exposed to a wood‐preserving waste extract, a complex mixture of polycyclic and polychlorinated chemicals

Wood preserving waste (WPW) sites contain numerous toxic compounds, including phenols, polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzodioxins, and dibenzofurans. Previous in vitro and in vivo 32P-postlabeling studies showed the induction of multiple carcinogen-DNA adducts by WPW extracts. We now have tested the hypothesis in a mouse skin bioassay that a WPW extract not only causes the formation of exogenous, xenobiotic-derived DNA adducts, but also alters the levels of endogenous DNA modifications. Skin DNA of female ICR mice treated topically with an organic WPW extract was found by 32P-postlabeling to contain significantly increased levels of bulky oxidative DNA lesions (type II I-compounds), in addition to exogenous PAH-derived adducts. The mechanism of this increase is postulated to proceed through electrophilic quinoid compounds, which presumably were formed from phenols by chemical reactions of waste material or biologically by oxidative metabolism. On the other hand, the levels of another class of endogenous DNA adducts (type I I-compounds) were reduced significantly in exposed skin DNA. This effect was explained by the presence of cytochrome P450 inducers in the extract. All three types of DNA alterations observed may play a significant role in carcinogenesis. Our results imply that in addition to exogenous carcinogen-DNA adducts, alterations of endogenous DNA modifications may need to be considered in evaluating carcinogenic risk from toxic chemical wastes and the effects of remediation measures. Environ. Mol. Mutagen. 29:372–378, 1997 © 1997 Wiley-Liss, Inc.

Comparative32P-postlabeling analysis of exogenous and endogenous DNA adducts in mouse skin exposed to a wood-preserving waste extract, a complex mixture of polycyclic and polychlorinated chemicals

Wood preserving waste (WPW) sites contain numerous toxic compounds, including phenols, polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzodioxins, and dibenzofurans. Previous in vitro and in vivo 32P-postlabeling studies showed the induction of multiple carcinogen-DNA adducts by WPW extracts. We now have tested the hypothesis in a mouse skin bioassay that a WPW extract not only causes the formation of exogenous, xenobiotic-derived DNA adducts, but also alters the levels of endogenous DNA modifications. Skin DNA of female ICR mice treated topically with an organic WPW extract was found by 32P-postlabeling to contain significantly increased levels of bulky oxidative DNA lesions (type II I-compounds), in addition to exogenous PAH-derived adducts. The mechanism of this increase is postulated to proceed through electrophilic quinoid compounds, which presumably were formed from phenols by chemical reactions of waste material or biologically by oxidative metabolism. On the other hand, the levels of another class of endogenous DNA adducts (type I I-compounds) were reduced significantly in exposed skin DNA. This effect was explained by the presence of cytochrome P450 inducers in the extract. All three types of DNA alterations observed may play a significant role in carcinogenesis. Our results imply that in addition to exogenous carcinogen-DNA adducts, alterations of endogenous DNA modifications may need to be considered in evaluating carcinogenic risk from toxic chemical wastes and the effects of remediation measures.

DNA damage induced in mouse tissues by organic wood preserving waste extracts as assayed by 32P-postlabeling.

Numerous wood preserving waste (WPW) sites in the United States pose genotoxic hazards. WPWs consist of complex mixtures containing toxic, including genotoxic, compounds which are derived from the preservatives coal tar creosote and pentachlorophenol (PCP) and other polychlorinated aromatics. The genotoxicity of WPW extracts, which has not been tested in mammals, cannot be evaluated on the basis of data for individual components because of possible compound interactions. Therefore, whole extracts need to be assayed. 32P-postlabeling represents a powerful tool to determine DNA adduct formation by complex genotoxic mixtures, such as cigarette smoke, diesel exhaust, and coke oven and foundry emissions in experimental animals and humans. In the present study, a mouse bioassay was used in combination with 32P-postlabeling to determine DNA adduct formation induced by hexane/acetone extracts of two samples from a WPW site. Female ICR mice were treated dermally with extract corresponding to 3 mg residue or vehicle control once per day for 2 days and killed 24 h later. Skin, lung, liver, kidney, and heart DNA preparations were assayed by nuclease P1-enhanced postlabeling. Adduct profiles were tissue-specific and displayed a multitude of non-polar DNA adducts with levels amounting to one adduct in 1.6 x 10(6) DNA nucleotides in skin (both extracts) and one adduct in 3.2 x 10(7) or 1.2 x 10(7) DNA nucleotides in liver (extract 1 or extract 2). Based on their chromatographic properties, these adducts appeared largely derived from polycyclic aromatic hydrocarbons (PAHs) present in the extracts. One of the major adducts was identified as the 32P-labeled derivative of the reaction product of 7 beta, 8 alpha-dihydroxy-9 alpha, 10 alpha-epoxy-7, 8,9,10-tetrahydrobenzo[a]pyrene (BPDE I) with N2 of deoxyguanosine. Total non-polar DNA adduct levels were highest in skin and lung, amounting to 17.4 and 24.0% of the skin values for extracts 1 and 2, respectively, in lung while the corresponding levels in liver were 5.0 and 12.6%. These results were in accord with the carcinogenic potencies of PAHs in these organs. Extract 2 induced higher adduct levels in internal organs, although its PAH concentrations were lower than those of extract 1, i.e. lung, liver, kidney, and heart had 1.4, 2.5, 1.9, and 1.7 times higher total adduct levels and 1.6, 3.3, 1.6, and 1.9 times higher benzo[a]pyrene adduct levels. With the exception of total adducts in lung, the differences between the two extracts were all significant, suggestive of compound interactions. The benzo[a]pyrene adduct levels in the five tissues correlated linearly with total adduct levels and thus represented a surrogate for the latter. Overall, the results suggest that DNA adducts in mouse tissues, as analyzed by 32P-postlabeling, are suitable biomarkers and dosimeters of the genotoxicity of WPW extracts.

Mutagenic Activity (Ames Test) of Wood-Preserving Waste Sludge Applied to Soil

In both laboratory (McGinnis et al. 1988; Aprill et al. 1990) and field soiltreatability studies (Brown et al. 1985a), the majority of hazardousconstituents present in creosote/pentachlorophenol (PCP) bottomsediment sludges have been rendered less toxic after undergoingdegradation or transformation.However, the present investigators,utilizing the Ames test to monitor potential detoxification of creosote/PCPsludge constituents during field land treatment studies, observed apersistent mutagenic residue remaining in surface soil a year or moreafter the sludge was applied (Donnelly et al. 1987; Barbee et al. 1992).Not surprisingly therefore, surface runoff from soils amended withcreosote/PCP bottom sediment sludge also displayed significant levels ofAmes test mutagenic activity even 360 days after sludge application(Davol et al. 1989). It was estimated that three or more years would berequired for the mutagenic activity of runoff water discharging from landtreated sludge to return to background levels. In addition, after one yearof treatment water soluble fractions and leachate extracted from acreosote sludge/soil mixture produced a toxic response in the Microtox

DNA damage induced by wood preserving waste extracts in vitro without metabolic activation, as assayed by 32P-postlabeling.

Aqueous wood preserving waste (WPW) extracts were tested for their ability to damage DNA in vitro without metabolic activation. Two extracts were prepared from a surface tar and a surface clay soil sample of a WPW site. As assayed by 32P-post-labelling incubation of DNA with these extracts gave rise to highly complex, extract-specific profiles of DNA adducts whose formation depended on the concentration of WPW material. Most of the adducts appeared to be derived from polycyclic aromatic hydrocarbons (PAHs). Three mg organic WPW residue gave rise to total adduct levels of 13.8 (extract 1) and 66.2 (extract 2) DNA modifications in 10(7) DNA nucleotides, corresponding to 13.9 and 26.9 modifications, respectively, per 10 mg of soil. Thus, extract 2 was more active, although the parent residue had a 1.4-times lower PAH content as determined by gas chromatography/mass spectrometry (GC/MS). DNA adduct formation presumably was a consequence of (i) free radical reactions, possibly involving semiquinones and oxygen free radicals, and (ii) reaction of direct-acting electrophiles, derived from metabolism of WPW toxicants by soil microorganisms. These reactions appeared to be more active in sample 2. The results suggest that ground water at WPW sites contains DNA-reactive compounds posing a cancer hazard to humans. The in vitro DNA adduct assay represents a novel tool to readily assess this type of hazard and the possible effects of remediation measures.

Bacterial mutagenicity of soil extracts from a bioremediation facility treating wood-preserving waste

Bioremediation is gaining acceptance as a viable alternative for remediating contaminated soils at Superfund sites. However, it has the potential for resulting in the production of intermediate breakdown products which may be more toxic and soluble than the parent compound. This study was designed to monitor the mutagenic activity of contaminated soils from an abandoned wood preserving facility undergoing bioremediation in an intensively managed land treatment unit (LTU). Sample collection included two waste samples, twelve soil samples from the LTU, one on- site control soil sample, and one off-site control sample. Samples were sequentially extracted with methylene chloride and methanol, and the residues from these extractions were dissolved in dimethyl sulfoxide for testing with the Salmonella/microsome assay (Ames test). Each extract was tested using strain TA98 with and without metabolic activation, and the results were used to measure the bacterial mutagenicity which is an indicator of the carcinogenic potential. Although chemical analysis had suggested that biodegradation had reduced the concentration of toxic organics to below method detection limits, the results of bioassay testing detected mutagenic chemicals still present in both lifts of soil in the LTU. The weighted activity (revertants per gram of soil) of the soil from the upper lift which had been in the LTU for only five weeks exceeded two times the background, whereas the weighted activities of soil samples from the lower lift which had been in the LTU for three months were within background values for this site. These data indicate that three months of remediation in an intensively managed LTU is sufficient to reduce the weighted activity of contaminated soil from this facility to near background levels.

Detecting Organic Contaminants in the Unsaturated Zone Using Soil and Soil-Pore Water Samples

ABSTRACT A lysimeter study was conducted to compare the effectiveness of soil core and soil-pore water samples in detecting the movement of organic constituents from land-treated industrial wastes. Lysimeters collected from the Bastrop (Udic Paleustalf), Padina (Grossarenic Paleustalf), and Weswood (Fluventic Ustochrept) soils were amended with a refinery separator sludge, a wood-preserving bottom sediment sludge, or a nonhalogenated solvent recovery sludge at rates of 50, 15, and 50 g kg−1, respectively. Soil-pore water samples from porous ceramic cups and soil cores were collected monthly at three depths in the lysimeters to monitor n-alkanes and polynuclear aromatic hydrocarbons from the petroleum waste, phenols and cresols from the wood-preserving waste, and aromatic solvents from the solvent recovery waste. The organic carbon normalized soil sorption coefficient (Koc) may be useful for determining when soil-pore water or soil core samples will be most effective in detecting organic chemicals in the u...

Mutagenic potential of runoff water from soils amended with three hazardous industrial wastes

The bacterial mutagenicity of runoff water from soils contaminated with hazardous industrial waste was monitored for a three-year period using Salmonella typhimurium strain TA98 with and without metabolic activation. The wastes included a wood-preserving waste, a combined American Petroleum Institute (API) separator/slop oil emulsion sludge and a storm-water runoff impoundment waste. The wastes were applied to a Weswood silt loam soil (Fluventic Ustochrept) and a Bastrop clay loam soil (Udic Paleustalf) at a rate of 3.1% (wt./wt.) for the wood-preserving waste and of 4.5% for the two refinery wastes. The results indicate that the runoff water from each of the waste-amended soils contained mutagenic constituents. The maximum specific activity was 783 net revertants per milligram residue, which was induced by the runoff water collected from the storm-water runoff impoundment-amended Weswood soil 360 d after application and assayed with metabolic activation. This sample also yielded the maximum weighted activity of 6,554 revertants per liter of runoff water. The mutagenic activities of the runoff water from all waste-amended soils displayed significant increases through 360 d after application and, in most cases, significant decreases in the samples collected approximately three years after application. The mutagenic activities of the runoff water from the Weswood soil were consistently greater than the activities of the runoff water from the Bastrop soil. These results indicate that three years or more may be required for the mutagenic activity of runoff water to return to background level, and that different soils will differ in their capacities to retain mutagenic chemicals during rainfall events.

Mutagenic activity of two soils amended with a wood-preserving waste

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMutagenic activity of two soils amended with a wood-preserving wasteKirby C. Donnelly, Phebe. Davol, K. W. Brown, M. Estirl, and J. C. ThomasCite this: Environ. Sci. Technol. 1987, 21, 1, 57–64Publication Date (Print):January 1, 1987Publication History Published online1 May 2002Published inissue 1 January 1987https://doi.org/10.1021/es00155a006RIGHTS & PERMISSIONSArticle Views54Altmetric-Citations20LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts