Publications

Human exposure to carbon monoxide can occur from automobile emissions, industrial processes, sidestream or mainstream cigarette smoke, and poorly ventilated appliances such as space heaters and gas stoves. Most researchers consider the major mechanism for the toxicity of carbon monoxide to be its ability to compete with oxygen for binding to hemoglobin, the protein that transports oxygen through the bloodstream and releases it to cells and tissues.

Ozone and nitrogen dioxide are highly reactive oxidant gases that are derived from the combustion of fossil fuels and the atmospheric transformation of these combustion products. A major unanswered question is whether or not exposure to oxidant air pollutants contributes to lung cancer. Dr. Witschi and colleagues at the University of California at Davis examined whether exposure to ozone or nitrogen dioxide enhances the development of tumors induced by the chemical carcinogen diethylnitrosamine (DEN), particularly neuroendocrine tumors, in the respiratory tract of hamsters.

Communication 2 provides information to decision makers on research that is potentially capable of narrowing uncertainties related to the health effects of specific air toxics. This report is based on the Mobile Air Toxics Workshop held in Monterey, CA, December 4–6 1992.

This publications contains two reports by Drs. Jonathan M. Samet, John D. Spengler, and colleagues, who conducted a prospective investigation of 1,205 healthy infants living in homes with gas or electric stoves in Albuquerque, NM. Nitrogen dioxide exposures were carefully estimated from repeated measurements in multiple locations in the subjects' homes throughout the entire 18-month observation period. Respiratory illnesses were monitored prospectively using a surveillance system based on daily parental diaries of respiratory signs and symptoms. Parental reports of illness episodes were validated in a subset of the population by comparison with clinical diagnoses and microbiological testing. Potential confounding factors that influence respiratory infections were reduced by selecting subjects whose parents did not smoke or intend to use day-care services outside the home.

This document contains two reports by Drs. McCool and Samet and their colleagues who were funded to develop and test methods for measuring ventilation in freely mobile subjects at home or at work. Drs. Dennis McCool and Domyung Paek at the Memorial Hospital in Rhode Island measured ventilation with a body surface displacement (BSD) model. Each subject wore wide elastic bands containing coated wire coils around the chest and abdomen and had special magnets affixed to the breastbone and navel, which yielded data about their breathing patterns, breath frequency, and ventilation. In the second study, Dr. Jonathan Samet and colleagues at Johns Hopkins University wanted to develop methods for estimating ventilation from heart rate for future epidemiologic studies. They used the Heartwatch, a portable, commercial device combining a small transmitter worn on the subject's chest with a wristwatch-style receiver that records heart rate.

Ozone and nitrogen dioxide are significant outdoor and indoor air pollutants that can cause lung damage. Both are termed oxidant gases because the oxygen atoms they contain react with a variety of lung components and produce injury. Dr. Bruce Freeman and colleagues at the University of Alabama, Birmingham examined oxidant injury to alveolar epithelial cells and tested whether supplementing the levels of antioxidants would modify the cells' resistance to damage.

Drs. Chaitman and coworkers at the St. Louis University School of Medicine examined whether there is a link between carbon monoxide exposure and arrhythmias in subjects with coronary artery disease. Carbon monoxide is a ubiquitous air pollutant. It is found in cigarette smoke and emissions from motor vehicles, industrial processes, and poorly ventilated combustion sources. The investigators studied 25 men and 5 women, aged 45 to 77 years, all of whom were nonsmokers with stable coronary artery disease and who had moderate levels of ventricular arrhythmias.

HEI Communications 1 contains abstracts for six feasibility studies that were funded under RFA 89-2: Health Effects of Chronic Ozone Inhalation: Collaborative National Toxicology Program–Health Effects Institute Studies: Pilot Studies.

Dr. George Leikauf and coworkers at the University of Cincinnati Medical Center examined the mechanism by which aldehyde inhalation can alter breathing patterns and damage cells lining the airways. Emissions from motor vehicles using gasoline and diesel fuels add to the outdoor levels of aldehydes, including formaldehyde and acrolein, which are known irritants of the respiratory tract. The investigators prposed to examine whether airway constriction due to exposure to aldehydes is caused by damage to airway cells, by the entry of white blood cells into the lungs, or both.

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.

The human health effects that result from breathing air pollutants depend on the amount of pollutant inhaled from the air (exposure dose) and the amount of inhaled material that stays in the respiratory tract (retained dose). Because the retained dose of a pollutant may damage the respiratory tract and cause disease, it is a key factor for determining appropriate government regulations for air pollutants. Drs.

In this pilot study, Dr. Mary Cook and colleagues at the Midwest Research Institute explored how exposure to methanol vapor might affect the human nervous system. Methanol could be used as an alternative fuel, but it may lead to increased levels of methanol and formaldehyde in the atmosphere. The investigators exposed 12 young male volunteers to either filtered air or methanol vapor and assessed their response using 20 commonly used tests of sensory, behavioral, and reasoning performance before, during, and after each exposure.