The H-4-II E enzyme induction bioassay was used for testing both pure reference substances and extracts of wildlife samples. Polychlorinated naphthalenes were found to be as active as enzyme inducers as certain coplanar polychlorinated biphenyls (PCBs). Also a mixture of polybrominated diphenyl ethers (Bromkal 70-5DE) was shown to induce enzyme activity. In extracts of herring, containing polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), bioassay and chemically derived TCDD-equivalents (TEQs) were nearly identical. When extracts containing other types of dioxin-like compounds as well were tested, the bioassay TEQs for most of them agreed well with chemical TEQs calculated for PCDDs, PCDFs and non-ortho PCBs. However, for ringed seal and whitefish, TEQs obtained from the bioassay were higher than those from the chemical analysis. Our results indicate that this bioassay is an excellent complement to chemical residue analysis and a useful tool in understanding the complex interactions of halogenated hydrocarbons. For risk assessment, such results should, however, be used most carefully as they are measured in vitro.

A dynamic flow-through exposure system was designed for mutagenicity studies of gaseous compounds in Salmonella. Salmonella typhimurium strain TA100 was the primary tester strain. The dose ranges were 0.5-20% of vinyl chloride, ethene, propene, and 1,3-butadiene, 1-200 ppm of ethylene oxide, 0.5-20 ppm of nitrogen dioxide, and 0.1-3.5 ppm of ozone. The gas flow rate was 250, 500, or 1,000 ml/min, and the exposure time was 6 or 7 hours. Of the tested gases, vinyl chloride, ethylene oxide, and nitrogen dioxide were mutagenic. Ethene, propene, and 1,3-butadiene were not mutagenic in this system. Ozone is bacteriotoxic, and no mutagenic effect could be demonstrated in the nontoxic dose range. The exposure system was considered suitable for studies on gaseous chemicals.

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Combined filter-, condensate-and XAD-extracts of flue gas samples from four different municipal solid waste (MSW) incineration plants were tested for mutagenic activity in the Ames Salmonella/microsome assay. The mutagenic activity in samples from two of the incinerators was relatively high, whereas the emission from the other two was in the same order of magnitude as from oilor coal-fired plants of equivalent size. Generally, the material collected did not require metabolic activation for mutagenic activity. The emission of mutagenic substances was statistically correlated to the emission of carbon monoxide and polyaromatic hydrocarbons (PAH). Thus, the amount of mutagenic material can be modulated by the combustion process. Fractionation studies showed that there is not only a quantitative but also a qualitative difference in mutagenic activity between samples representing different combustion conditions.

In order to investigate the possible formation of mutagenic compounds from alkenes emitted in ambient air, laboratory experiments were performed with Salmonella typhimurium strain TA100 in a small-scale flow-through exposure system. The reaction time for mixtures of alkenes with ozone or nitrogen dioxide was 40 minutes, and the exposure time for bacteria was 6 hours. Ozone gave rise to a small mutagenic effect in combination with 1,3-butadiene or vinyl chloride, with and without ultraviolet (UV) irradiation, but not in combination with ethene or propene. Nitrogen dioxide gave rise to a mutagenic effect in combination with propene, 1,3-butadiene, or vinyl chloride, but only after UV irradiation. The mutagenic activity was highest with butadiene and seemed to be dose-related to the concentration of nitrogen dioxide. Nitrogen dioxide with ethene did not produce a mutagenic effect. A mixture of ethene, propene, and butadiene, tested with ozone or nitrogen dioxide with UV irradiation, did not potentiate each other's mutagenic effect.