Research Reports

Nitropyrenes are a class of chemicals found in diesel engine exhaust that can form DNA adducts and are suspected animal carcinogens. Dr. Beland at the University of Arkansas for Medical Sciences examined the relationship between DNA adducts and cancer in laboratory animals treated with 1-nitropyrene, the major nitropyrene present in diesel engine exhaust. The investigator used state-of-the-art techniques to study DNA adducts formed from 1-nitropyrene under different conditions of exposure, with an emphasis on identifying unique adducts that had not been recognized before.

Nitrogen dioxide is an ubiquitous air pollutant resulting from the combustion of fossil fuels. When inhaled at high levels, it reacts with and damages lung cells, including those cells that fight infection. This damage can affect breathing and may increase the risk of respiratory infections. Dr. J.K. Davis and his colleagues at the University of Alabama, Birmingham examined whether exposure to lower levels of nitrogen dioxide (less than 5 ppm) compromises mouse lung defense.

Ozone is a highly reactive gas that is a pervasive air pollutant at ground level. It is a major component of urban smog, forming when emissions from mobile and industrial sources interact with sunlight. When inhaled, ozone can cause cough, shortness of breath, and transient changes in breathing patterns; however the health significance of these effects is unknown. Drs. Kenneth Donaldson and coworkers at the Institute of Occupational Medicine examined whether exposure to ozone activates white blood cells to release substances that can damage lung tissue.

Nitrogen dioxide is an ubiquitous air pollutant that can react with and damages lung cells when inhaled at high levels. Although outdoor and indoor levels of nitrogen dioxide are usually below the annual standard of 0.053 ppm, peaks can occur that reach up to 10 times this standard. Dr. Mark Utell and coworkers at the University of Rochester examined the human health impacts of higher (peak) levels of nitrogen dioxide that exceed the annual standard. The investigators exposed healthy, nonasthmatic, human volunteers to either nitrogen dioxide or filtered air for three hours.

This report describes a study by Drs. Yu and Yoon to mathematically predict the lung burden in rats and humans of diesel exhaust particles (DEP) from automobile emissions. Building on a previously constructed model describing DEP deposition, the present work focused on clearance and retention of DEPs deposited in the lung. The transport rates of each component of DEPs were derived using experimental data and mathematical approximations. The complete model was first developed for rats and then extrapolated to humans of different age groups.

This report describes a study by Dr. Last to investigate possible synergistic effects of multiple air pollutants on pulmonary measures in rats. Rats were exposed for 1-9 days to mixtures of O₃ or NO₂ and aerosols of sulfuric acid, ammonium sulfate, or sodium chloride, and to each pollutant individually. Responses were evaluated by various biochemical and morphometric analyses of lung tissue and lavage fluid. An additional preliminary experiment treated exposed rats in vivo with various free-radical scavengers to elucidate possible protective properties.

This report describes a study by Dr. Farber and colleagues to investigate the effect of carbon monoxide (CO) exposure on cardiac parameters in dogs. They tested dogs that developed ventricular fibrillation during a test of exercise and acute myocardial ischemia (i.e. that were susceptible) and dogs that survived the test without fatal arrhythmias (i.e that were resistant). Susceptible and resistant dogs were exposed to a concentration of CO sufficient to raise carboxyhemoglobin levels to 5 – 15%.

This report describes a study by Dr. Verrier and colleagues to explore the effects of acute carbon monoxide (CO) exposure on cardiac electrical stability through a number of biological models. Experiments involved cardiac electrical testing of conscious and anesthetized dogs with normal and ischemic hearts who were exposed to CO for 2 or 24 hours. The experimental plan explored both the direct effects of CO exposure on the myocardium and possible indirect effects through alterations in the ability of platelets to aggregate or changes in nervous system activity.

This report describes a study by Dr. Moon and colleagues to investigate the carcinogenic potential of 1-nitropyrene, a mutagenic constituent of diesel exhaust particles, using a hamster respiratory-carcinogenesis model. Male hamsters were exposed to 1 or 2 mg of 1-nitropyrene via intratracheal administration either once or twice a week for 92 weeks. In order to study activity as a cocarcinogen, 1 or 2 mg of 1-nitropyrene was administered in combination with 0.25 mg of the known environmental carcinogen benzo[α]pyrene once per week for 92 weeks.