as drooling, excessive urination, or diarrhea (Berteau et al., 1989). For six pesticides (chlordane, heptachlor, aldrin, chlorpyrifos, diazinon, and gamma-BHC) analyzed in EPA's NOPES study, the mean air exposures were always or often higher than the estimated dietary exposure for the same compounds (EPA, 1990).

Fenske et al. (1990) measured chlorpyrifos (Dursban) concentrations following its application for flea treatment in a carpeted apartment. They found that the chlorpyrifos vapors measured in the infant breathing zone (25 cm above the carpet) were substantially higher than those measured in the sitting adult's breathing zone. Time-weighted averages for the 24-hour postapplication period in the infant breathing zone were 41.2 and 66.8 µg/m3 for ventilated and nonventilated rooms, respectively; this is substantially higher than the interim guideline of 10 µg/m3 proposed by the National Research Council's Committee on Toxicology for chlorpyrifos in indoor air following termiticide treatments (NRC, 1982). In addition, air concentrations increased from the time of application up to 5 to 7 hours later. The authors suggested that the treated carpet served as a source of volatilized chlorpyrifos and that although open windows provided mixing and dilution of air 1 m above the carpet, concentrations near the floor were affected much less (Fenske et al., 1990).

The short- and long-term health effects to exposure to commonly used home-use pesticide products are largely unknown. In assessing risk for infants in chlorpyrifos-treated homes, based on several conservative assumptions, Berteau et al. (1989) calculated an absorbed dose of 2.68 mg/kg. Fenske et al. (1990) found that the total estimated absorbed chlorpyrifos dose for infants exceeded the EPA's no-observed-effect level (NOEL) of 0.03 mg/kg/day in each case. The NOEL for chlorpyrifos is based on measurable changes in plasma acetylcholinesterase.

The indoor use of pesticides in public buildings such as schools and day-care centers leads to an additional source of exposure for children. In one episode, employees of a school for mentally handicapped children became ill within hours of entering a building that had been treated for roaches 3 days earlier and had not been ventilated. No students were admitted into the building until 14 days after the incident, when air levels of the pesticides used (dichlorvos and propoxur) had decreased to an acceptably safe level (White et al., 1987). An air analysis indicated that the levels of dichlorvos in the air were decreasing over time, but at a much slower rate than was expected from the data provided by the manufacturer.

Chlordane was the leading compound for controlling termites in homes for several years. Although it has since been canceled by the EPA for use as a termiticide, research demonstrates that chlordane air levels decline



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