Use of limited protocols to evaluate the genotoxicity of hazardous wastes in mammalian cell assays: comparison to Salmonella

Cancer incidence among women in the Norwegian pulp and paper industry

BACKGROUND

The aim of the present study was to investigate cancer risk among women working in the Norwegian pulp and paper industry. The cohort included a total of 4,247 workers employed for at least one year between 1920 and 1993 (108,095 person-years), 85% of them as paper or administration workers.

METHODS

The follow-up period for cancer was from 1953-1993. No data of exposure measurements were available. The analyses were based on comparisons of standard incidence ratios. The expected numbers of cancer cases were calculated using the five-year age-specific incidence rates for the entire female population.

RESULTS

During the follow-up period, 380 new cases of cancer were observed vs. 322 expected (SIR = 1.2, 95% CI = 1.07-1.30). An excess risk of ovarian cancer was found (SIR = 1.5, 95% CI = 1.07-2.09). The SIR was highest among those younger than 55 years, and mostly among those working in paper departments. Short-term workers showed increased risk of lung and bladder cancer.

CONCLUSIONS

Based on results from the present study, the increased risk of ovarian cancer is difficult to interpret, since existing knowledge of its etiology is limited. However, these women might have been exposed to various work-related agents such as talc, microbes, and different types of paper dust.

In vitro embryotoxicity of petroleum creosote monitored via mouse preimplantation embryo culture

A mouse preimplantation embryo culture system was utilized to characterize the in vitro embryotoxicity of petroleum creosote (PC), a complex mixture of aliphatic and polycyclic aromatic hydrocarbons. ICR mouse embryos, collected on d 3.5 of gestation (blastocyst stage), were exposed for 1 h to varying concentrations of petroleum creosote in serum-supplemented culture medium. Parallel embryo cultures were exposed to PC in medium supplemented with rodent hepatic S9 microsomal fractions to monitor the role of bioactivation in PC-induced embryotoxicity. Embryos were subsequently cultured in control medium for 72 h and observed for viability as well as specific, time-dependent developmental end points--hatching and attachment to the culture dish at 48 h, and trophoblastic outgrowth with a distinct inner cell mass at 72 h. Embryonic viability varied in inverse proportion to PC concentration. Petroleum creosote caused embryolethal effects at concentrations of 33 micrograms/ml of culture medium and 54 micrograms/ml. Embryotoxicity was not observed at 22 micrograms/ml. Culture supplementation with rodent hepatic S9 fractions did not modify, either qualitatively or quantitatively, the embryotoxicity of PC in vitro. These findings implicate PC as a prenatal toxicant and support environmental and human health concerns regarding PC exposure from PC-containing chemical waste sites.

The genotoxicity of industrial wastes and effluents

A review of the literature published on the genotoxicity of industrial wastes and effluents using short-term genetic bioassays is presented in this document. The importance of this task arises from the ubiquity of genotoxic compounds in the environment and the need to identify the sources of contamination so that efforts aimed at control and minimization can be implemented. Of even greater significance is the immediate concern for the welfare of human health and the environment. Subheadings of this document include a description of the genetic bioassays that have been used to test industrial wastes, a compendium of methods commonly used to prepare crude waste samples for bioassay, and a review of the genetic toxicity of wastes and effluents. Wastes and effluents have been grouped according to industrial source. Major categories include chemical and allied products, pulp and paper manufacturing, defense and munitions, petroleum refining, primary metal industries, and miscellaneous industrial manufacturers. Within each industrial category, a synopsis of individual genetic toxicity studies is presented, followed by an interpretation of results on a comprehensive, industry-wide basis. In this evaluation, a discussion of the types and extent of genotoxic damage caused by a particular set of wastes is presented, and potential sources of genotoxic activity are identified. Concluding the document is a commentary, which discloses potential shortcomings in the way in which current legislation protects human heath and the environment from the release of genotoxic substances via industrial wastes and effluents. It also provides an assessment of the genotoxic burden that industrial wastes place on the environment.

Toxicological evaluation of complex industrial wastes: implications for exposure assessment

We evaluated a variety of short-term bioassays to construct a battery of tests that could be used for assessing the biological effects of potentially hazardous complex industrial wastes. Ten samples were studied for hepatotoxicity; these samples and an additional 5 were studied for mutagenicity. Although the data are limited to these samples, the results suggest that the Salmonella assay (strain TA98) or a prophage-induction assay (both in the presence of S9) in combination with determination of relative liver weight and levels of a set of serum enzymes in rats may provide a battery of tests suitable to characterize complex industrial wastes for mutagenic and hepatotoxic potential. The biological activities exhibited by the wastes were not readily predicted by the chemical profiles of the wastes, emphasizing the importance of characterizing potentially hazardous complex industrial wastes by both chemical and biological means. DNA from liver, lung and bladder of rats exposed to some of the wastes was analyzed by the 32P-postlabeling technique for the presence of DNA adducts. A waste that produced mutagenic urine produced a DNA adduct in bladder DNA. The implications of this approach for assessment of exposure to complex hazardous waste mixtures are discussed.

Mutagenicity in salmonella of hazardous wastes and urine from rats fed these wastes

15 hazardous industrial waste samples were evaluated for mutagenicity in the Salmonella plate-incorporation assay using strains TA98 and TA100 in the presence and absence of Aroclor 1254-induced rat liver S9. Dichloromethane/methanol extracts of the crude wastes were also evaluated. 7 of the crude wastes were mutagenic, but only 2 of the extracts of these 7 wastes were mutagenic; extracts of 2 additional wastes also were mutagenic. In addition, 10 of the crude wastes were administered by gavage to F-344 rats, and 24-h urine samples were collected. Of the 10 raw urines evaluated, 3 were mutagenic in strain TA98 in the presence of S9 and beta-glucuronidase. The 3 crude wastes that produced these 3 mutagenic urines were, themselves, mutagenic. Adequate volumes of 6 of the 10 raw urines were available for extraction/concentration. These 6 urines were incubated with beta-glucuronidase and eluted through Sep-Pak C18 columns; the methanol eluates of 3 of the urines were mutagenic, and these were the same 3 whose raw urines also were mutagenic. In general, the C18/methanol extraction procedure reduced the cytotoxicity and increased the mutagenic potency of the urines. To our knowledge, this is the first report of the mutagenicity of urine from rodents exposed to hazardous wastes. Based on the present results, the use of only strain TA98 in the presence of S9 might be adequate for general screening of hazardous wastes or waste extracts for genotoxicity. The urinary mutagenesis assay does not appear to be a useful adjunct to the Salmonella assay for screening hazardous wastes. The problems associated with chemically fractionating diverse types of hazardous wastes for bioassay are also discussed.