Air Toxics

Drs. Pollack and Brouwer at the University of North Carolina determined the relationship between methanol exposure and its uptake into and elimination from the blood of nonpregnant and pregnant rodents. The investigators exposed rats and mice at several different stages of gestation to methanol intravenously or orally (doses ranged from 100 mg/kg of body weight to 2,500 mg/kg) or by inhalation (1,000 to 20,000 ppm for 8 hours). They measured blood, urine, and amniotic fluid concentrations of methanol and used the data to develop a model of methanol distribution in rodents.

A Special Report of the Institute's Oxygenates Evaluation Committee. Oxygenated fuel (usually referred to as oxyfuel) was formulated to reduce carbon monoxide emissions and contains at least 2.7% oxygen by adding methyl tert-butyl ether (MTBE) or ethanol. Reformulated gasoline was formulated to help reduce ground-level ozone concentrations and contains at least 2% oxygen, has a reduced content of benzene and other aromatic compounds, and produces limited emissions of total air toxics. The introduction of fuels containing oxygenates elicited concerns from workers and the general public in some areas, including reports of unpleasant odors, headaches, or other symptoms attributed to the fuels, and questions about their effects on the cost of gasoline, the performance of engines, and fuel economy. This Special Report summarizes an intensive review of (1) the existing science of the health effects of oxygenates, (2) the risk evaluations done by the EPA in 1993 and 1994, and (3) in a qualitative way, the health effects of exposure to the new additives as they relate to the health effects of other pollutants whose levels in emissions change when fuels containing oxygenates are used.

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.

Dr. Klein-Szanto and colleagues at the Fox Chase Cancer Center employed a novel exposure system to explore the capacity of formaldehyde to cause cancerous changes in human epithelial cells. Formaldehyde is classified as a toxic air pollutant and is emitted in exhaust of motor vehicles, but whether or not formaldehyde is injurious to human health is controversial. The investigators obtained autopsy samples from human infant airways and from adult nasal tissue.

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.