Mutagenicity and tumor initiating activity of methylated benzo[b]fluoranthenes

New structural alerts for Ames mutagenicity discovered using emerging pattern mining techniques

The discovered patterns are used to develop new structural alerts for mutagenicity in the Derek Nexus expert system.

Toxicological evaluation of an electrically heated cigarette. Part 3: Genotoxicity and cytotoxicity of mainstream smoke

The in vitro toxicity of cigarette mainstream smoke from an electrically heated cigarette (EHC) with controlled combustion was compared with that of the standard University of Kentucky Reference Cigarette 1R4F. In the Salmonella reverse mutation assay, strains TA98, TA100, TA102, TA1535 and TA1537 were used in the absence and presence of a metabolic promutagen activation system (S9) to determine the mutagenic potential of the total particulate matter (TPM), which was collected on a glass-fiber filter. In the neutral red uptake assay, mouse embryo BALB/c 3T3 cells were used to determine the cytotoxic potential of TPM as well as of the water-solubles in the gas/vapor phase trapped in phosphate-buffered saline. The TPM from the electrically heated cigarette was up to 90% lower in mutagenicity than that of the 1R4F calculated on an equal TPM basis. This reduction in mutagenicity is consistent with the significantly lower concentration of nearly all constituents analyzed in EHC smoke. With regard to cytotoxicity when calculated on an equal TPM basis, TPM from the electrically heated cigarette was 40% less active relative to the 1R4F. When calculated on a per cigarette basis, the cytotoxicity of both the TPM fraction and the water-solubles in the gas/vapor phase of smoke from the EHC was ca. 80% lower relative to the 1R4F.

ATSDR evaluation of health effects of chemicals. IV. Polycyclic aromatic hydrocarbons (PAHs): understanding a complex problem

Polycyclic Aromatic Hydrocarbons (PAHs) are a group of chemicals that are formed during the incomplete burning of coal, oil, gas, wood, garbage, or other organic substances, such as tobacco and charbroiled meat. There are more than 100 PAHs. PAHs generally occur as complex mixtures (for example, as part of products such as soot), not as single compounds. PAHs are found throughout the environment in the air, water, and soil. As part of its mandate, the Agency for Toxic Substances and Disease Registry (ATSDR) prepares toxicological profiles on hazardous chemicals, including PAHs (ATSDR, 1995), found at facilities on the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) National Priorities List (NPL) and which pose the most significant potential threat to human health, as determined by ATSDR and the Environmental Protection Agency (EPA). These profiles include information on health effects of chemicals from different routes and durations of exposure, their potential for exposure, regulations and advisories, and the adequacy of the existing database. Assessing the health effects of PAHs is a major challenge because environmental exposures to these chemicals are usually to complex mixtures of PAHs with other chemicals. The biological consequences of human exposure to mixtures of PAHs depend on the toxicity, carcinogenic and noncarcinogenic, of the individual components of the mixture, the types of interactions among them, and confounding factors that are not thoroughly understood. Also identified are components of exposure and health effects research needed on PAHs that will allow estimation of realistic human health risks posed by exposures to PAHs. The exposure assessment component of research should focus on (1) development of reliable analytical methods for the determination of bioavailable PAHs following ingestion, (2) estimation of bioavailable PAHs from environmental media, particularly the determination of particle-bound PAHs, (3) data on ambient levels of PAHs metabolites in tissues/fluids of control populations, and (4) the need for a critical evaluation of current levels of PAHs found in environmental media including data from hazardous waste sites. The health effects component should focus on obtaining information on (1) the health effects of mixtures of PAHs particularly their noncarcinogenic effects in humans, and (2) their toxicokinetics. This report provides excerpts from the toxicological profile of PAHs (ATSDR, 1995) that contains more detailed information.