Concentrations of diazinon, chlorpyrifos, and bendiocarb after application in offices

Airborne and surface concentrations of diazinon, chlorpyrifos (Dursban), and bendiocarb (Ficam) were measured at intervals up to 10 days after broadcast spray application onto the floors of seven offices. Results from this work can provide information to evaluate health hazards for workers and others entering treated buildings and can assist public agencies in setting guidelines or regulations. Diazinon and chlorpyrifos airborne concentrations peaked 4 hr after application at 163 and 27 micrograms/m3 of air sampled, respectively. The highest level of bendiocarb (2.7 micrograms/m3) was measured during treatment. Airborne concentrations measured for diazinon indicate that building occupants should not enter unventilated rooms for at least 2 days after spraying. Reentry into unventilated rooms 1 day after treatment with chlorpyrifos or bendiocarb would appear to be safe, however. Residues on aluminum plates and furniture were examined at intervals of up to 48 hr after spraying. In many cases, surface concentrations were higher at 24 or 48 hr than at 1 hr. Concentrations of residues removed from wood and painted metal furniture generally were higher than those on the aluminum plates. Peak residue concentrations were diazinon, 38 ng/cm2 of surface area sampled at 48 hr; chlorpyrifos, 5.9 ng/cm2 at 48 hr; and bendiocarb, 25 ng/cm2 at 1 and 24 hr. Workers who must enter buildings after insecticide application often are unaware of treatment plans and, therefore, are unable to take precautions to minimize their exposure. Inhalation and skin contact with insecticides can be reduced by providing office workers and building occupants with information on treatment times, health effects of insecticide overexposure, steps to take to reduce contact, and the perceived health risk. It is essential that treated areas be ventilated adequately before workers return to their offices.