An Ab initio study of the relationship between nitroarene mutagenicity and electron affinity.

Electron affinities, approximated by lowest unoccupied molecular orbital (LUMO) energies, were determined for an extensive group of nitrated polycyclic aromatic hydrocarbons by ab initio methods at the STO-3G level. Significant correlations were demonstrated between nitroarene LUMO energy and the corresponding mutagenic activity in Salmonella typhimurium strains TA98, TA100, TA1537, and TA1538. An analogous correlation using Hückel calculations was substantially poorer. A correlation between nitro group rotation and LUMO energy was related to pi-conjugation about the C--N bond. Analysis of aryl substituent effects on nitrenium ion stability implicated additional nitro substitution in certain systems to be destabilizing. The results suggest a means for predicting nitroarene mutagenic activity and for assessing the role of metabolic intermediates.

Toxicity of polybrominated biphenyls (PBBs) in Domestic and laboratory animals.

The composition, environmental fate, and effects of the polybrominated biphenyls (Firemaster BP-6 or FF-1) involved in the accidental contamination of cattle feed in Michigan in 1973 are reviewed. Toxic effects referred to in this report are limited to those occurring in domestic and laboratory animals and include general toxicity, neurobehavioral toxicity, immunotoxicity, reproductive toxicity, mutagenicity and carcinogenicity. The absorption, distribution, biotransformation and elimination of these polybrominated biphenyls are discussed along with the interactions with other chemicals and drugs.

Haloethylene-related compounds of industrial, environmental, and medical significance.

A broad-based literature survey was made for chemicals that contain either a haloethylene or a related substructure. Two hundred and sixty-two compounds, including synthetic intermediates, pesticides, solvents, drugs, food components, natural products, and metabolites, are grouped by their structures. Some are in current use or are bioavailable while little exposure is expected from others. As more biologic-response information is reported for small compounds of these types, it should become possible to select others for research on additional questions of structure-activity relationships. Some of the compounds are widespread while others are not. Some are used or found in large amounts while others may be trace contaminants, minor or more major by-products of synthesis or isolation. The pesticides and solvents, for example, are knowingly and often deliberately released to the environment, sometimes in very large quantities. Inadvertent release also occurs, sometimes referred to as fugitive emission. Food contaminants and drugs are directly accessible to humans. Sparsely distributed natural products could be accessible to humans, for example, via the food chain. Some of the compounds in food may be formed during preparation, storage or metabolically. Last, the haloethylene function has often been synthesized into compounds in order to achieve desired biologic activities. There are many types and degrees of relatedness of structure, depending upon atomic dimensions and stereochemical, polar, resonance, and other factors. Furthermore, for some chemical series, biologic responses are continuously variable while, in other cases, it is not uncommon that qualitatively different types of response occur with apparently very close homologs. Genetic, metabolic, and behavioral factors affecting response must also be considered. Thus, safety or hazard cannot yet be predicted conclusively by apparent relatedness of structure alone. Also, since the tables are noncomprehensive, some relevant compounds have likely been omitted. The haloalkanes, for example, are not here because of their large number, despite the knowledge that some are either metabolized or nonbiologically converted to haloalkenes.

Indices of potential lead hazard.

This review is concerned with the concentrations of lead in human whole blood, erythrocytes, plasma, serum, soft tissues, bone, and urine. The extent to which redistribution of some of the bound lead occurs is outlines. The effects of lead on enzyme activities and on the accumulation of metabolic intermediates in the blood and urine are described. A brief section deals with the range of signs and symptoms that can occur and differences seen between symptomatic children and adults.