Reduced toxicological activity of cigarette smoke by the addition of ammonium magnesium phosphate to the paper of an electrically heated cigarette: smoke chemistry and in vitro cytotoxicity and genotoxicity.

The effects of the addition of ammonium magnesium phosphate (AMP) to the paper of an electrically heated cigarette (EHC) prototype on smoke composition and toxicity were quantified and the underlying mechanisms investigated. Smoke from EHC prototypes with and without AMP and from conventional cigarettes, i.e. the University of Kentucky Standard Reference Cigarette 1R4F and eight American-blend market cigarettes, was compared. Endpoints for comparison were smoke chemistry, where toxic constituents were measured, cytotoxic activity, as measured in murine fibroblasts embryo cells by the Neutral Red Uptake Assay, and genotoxic activity, as measured in bacteria by the Salmonella Reverse Mutation Assay and in murine lymphoma cells by the TK Assay. The addition of AMP to the EHC led to a reduction of toxic substances and toxicological activity of approximately 30% compared to the EHC without AMP. Compared to the conventional cigarettes, the EHC with AMP showed reductions of 75-90%. Smoke from the EHCs generated in nitrogen atmospheres supplemented with different concentrations of ammonia and oxygen was assayed for its in vitro cytotoxicity and genotoxicity. The results indicate that the ammonia released by AMP at the heating site of the EHC is responsible for the reductions in cytotoxicity and mutagenicity for the EHC with AMP compared with the EHC without AMP. Thus, while the EHC approach distinctly reduces toxic smoke constituents compared to conventional cigarettes, the use of AMP in the paper of an EHC leads to further distinct reductions. In the study presented here, in vitro assays were used as quantitative tools to investigate toxicity-related mechanisms.

Risk based tiered approach (RBTASM) for pollution prevention.

Effective management of human health and ecological hazards in the manufacturing and maintenance environment can be achieved by focusing on the risks associated with these operations. The NDCEE Industrial Health Risk Assessment (IHRA) Program is developing a comprehensive approach to risk analysis applied to existing processes and used to evaluate alternatives. The IHRA Risk-Based Tiered Approach (RBTASM) builds on the American Society for Testing and Materials (ASTM) Risk-Based Corrective Action (RBCA) effort to remediate underground storage tanks. Using readily available information, a semi-quantitative ranking of alternatives based on environmental, safety, and occupational health criteria was produced. A Rapid Screening Assessment of alternative corrosion protection products was performed on behalf of the Joint Group on Acquisition Pollution Prevention (JG-APP). Using the RBTASM in pollution prevention alternative selection required higher tiered analysis and more detailed assessment of human health risks under site-specific conditions. This example illustrates the RBTASM for a organic finishing line using three different products (one conventional spray and two alternative powder coats). The human health risk information developed using the RBTASM is considered along with product performance, regulatory, and cost information by risk managers downselecting alternatives for implementation or further analysis.

Estimation of chemical hazards in breast milk.

The presence in the workplace of women who desire to breast feed has complicated the interpretation of what constitutes a safe work environment. There is concern that levels of chemicals found safe for occupational exposure may result in unacceptably high levels of those same chemicals in breast milk. To date, there is no evidence of harm to breast-feeding infants whose mothers are not exposed above a permissible exposure limit (PEL). While we may take some comfort in this, "no evidence of harm" is not the same as "evidence of no harm." Unfortunately, the latter, being a negative, can never be proven. It is with this in mind that this paper is written. We present basic data for a systems approach to determining the hazard presented by a substance in breast milk.

Regulation of hepatic monooxygenases by phenobarbital, 3-methylcholanthrene, and polychlorinated biphenyls in rapid and slow acetylator mice.

A/J and C57BL/6J inbred mouse strains have been previously used as models of slow and fast acetylators, respectively, of human acetylator polymorphism. Studies were carried out to characterize possible differences in basal activities of hepatic monooxygenases and the response of these mouse strains to microsomal enzyme inducers. No significant difference in cytochrome P-450 content and associated enzyme activities of ethylmorphine N-demethylase and benzo(a)pyrene hydroxylase were observed between the two strains. The administration of the inducers, phenobarbital or the polychlorinated biphenyl mixture Aroclor 1254, resulted in significant increases in cytochrome P-450 and ethylmorphine N-demethylase activity and minimal changes in benzo(a)pyrene hydroxylase activity in both strains. Pretreatment with 3-methylcholanthrene resulted in little or no increase in N-demethylase activity in both strains. The polycyclic hydrocarbon caused a CO difference spectral shift to a lower wavelength only in the C57BL/6J mice. Further, it increased benzo(a)pyrene hydroxylase activity in both strains, but to a greater extent in the C57BL/6J strain. Electrophoretic studies using solubilized microsomal preparations confirmed the findings that the fast acetylators were highly responsive to the inducing properties of the polycyclic aromatic hydrocarbon, whereas the slow acetylators were relatively much less responsive to its inducing properties. The latter strain appeared to be more responsive to the inducing properties of the phenobarbital class of inducers, as reflected in the inducibility of cytochrome P-450 and the associated enzymic activities in the liver.

Comparative effects of ethanol administration on hepatic monooxygenases in rats and mice.

The inducing effects of chronic ethanol ingestion on hepatic monooxygenases in Sprague-Dawley and Long-Evans rats, and A/J and C57BL/6J mice, were studied. Cytochrome P-450 content was significantly increased in livers of all animals receiving the experimental ethanol-containing liquid diet. The CO-difference spectra of microsomes from ethanol-treated animals showed a shift in the absorbance maximum to 451-452 nm, compared to the absorbance maximum of 450 nm observed with microsomes from control animals. Ethylmorphine N-demethylase and benzo[a]pyrene hydroxylase activities in livers of ethanol-treated animals were minimally affected. The shift in the absorbance maxima to longer wavelengths in the CO-difference spectrum and the minimal effects on the metabolism of ethylmorphine and benzo[a]pyrene demonstrate that ethanol differs in its inducing properties, when compared to the properties of the two widely used hepatic microsomal enzyme inducers, phenobarbital and 3-methylcholanthrene. In contrast to the minimal effects observed on the metabolism of ethylmorphine and benzo[a]pyrene, several fold increases were observed in hepatic 7-ethoxycoumarin 0-deethylase and aniline hydroxylase activities in the treated animals. Polyacrylamide gel electrophoresis of hepatic microsomes from those animals receiving ethanol revealed protein band(s) in the cytochrome P-450 molecular weight region, the intensities of which were markedly increased relative to that from control animals. The heme-associated peroxidase activity was also increased in the same molecular weight region. The results of the present spectral, catalytic, and electrophoretic studies demonstrate that in mice, as in rats, chronic ethanol treatment causes the induction of specific cytochrome(s) P-450 with preferential activity toward aniline and 7-ethoxycoumarin.

Isopropanol enhancement of cytochrome P-450-dependent monooxygenase activities and its effects on carbon tetrachloride intoxication.

Acute or chronic treatment of rats with isopropanol caused a significant increase in hepatic cytochrome P-450 content and a two- to threefold increase in aniline hydroxylase and 7-ethoxycoumarin O-deethylase activities, but no significant change in ethylmorphine N-demethylase or benzo(a)pyrene hydroxylase activity. In rats treated with isopropanol and challenged with CCl4, liver toxicity of CCl4 was characteristically potentiated, as assessed by elevation of serum glutamic-pyruvic transaminase (SGPT) levels. Isopropanol pretreatment also potentiated CCl4-induced damage to the hepatic monooxygenase system. In addition to a decrease in cytochrome P-450, rats treated with isopropanol and challenged with CCl4 showed a nonspecific decrease not only in aniline hydroxylase and 7-ethoxycoumarin O-deethylase activities, but also in ethylmorphine N-demethylase, benzo(a)pyrene hydroxylase, and NADPH-cytochrome c reductase activities. These results were confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of solubilized microsomes. The electrophoretic results showed that isopropanol pretreatment markedly potentiated the CCl4-caused destruction of cytochrome P-450 hemeproteins. The data strongly suggest that isopropanol increases one or more forms of cytochrome P-450 which selectively enhance the metabolism of CCl4 to an active metabolite. This active metabolite then causes a nonselective damage to the microsomal mixed-function oxidase system.