Indoor spraying with the pyrethroid insecticide lambda-cyhalothrin: effects on spraymen and inhabitants of sprayed houses

In March 1990 a study was carried out in the village of Kicheba, United Republic of Tanzania, in which the pyrethroid insecticide lambda-cyhalothrin was sprayed on all the internal surfaces of houses and other shelters at a coverage of about 25 mg of active ingredient per m2. Every day for 6 days, 12 spraymen and 3 squad-leaders were interviewed about symptoms of overexposure to the insecticide. Each sprayman used up to 62 g of lambda-cyhalothrin over 2.7-5.1 hours every day. All the spraymen complained at least once of symptoms that were related to exposure to lambda-cyhalothrin, the commonest being itching and burning of the face, and nose or throat irritation frequently accompanied by sneezing or coughing. Facial symptoms occurred on non-protected areas only. The symptoms were experienced at various times after the beginning of exposure and disappeared before the following morning. The number of subjects affected and the duration of their facial symptoms were proportional to the amount of compound sprayed. A sample of individuals was interviewed 1 day and 5-6 days after their houses had been sprayed. One woman, who entered her house 30 minutes after the end of spraying, complained of periorbicular itching, but this lasted only a few minutes. No other significant, insecticide-related adverse effect was reported by the inhabitants of the sprayed houses.