| Abstract: | Hut and village-scale trials with solid and liquid-type dichlorvos dispensers were carried out in 1961 in the vicinity of Lagos, Nigeria, by the WHO Insecticide Testing Unit. Bioassay results indicated that with a single application satisfactory mortalities of caged mosquitos could be obtained for a period of 12-13 weeks in mud-walled huts, whether with galvanized corrugated-iron roofs or with thatched roofs. Chemical analysis of air samples showed that satisfactory concentrations of dichlorvos vapour were maintained throughout the huts for about 12 weeks, after which time sublethal concentrations were observed first near the floors of the dwellings. No depression in blood or plasma cholinesterase was noted in the exposed inhabitants |
