3.2. Pyrethroid concentrations in house dust
Of the five pyrethroids tested for, at least one pyrethroid, generally
permethrin, was detected in 89% of the dust samples. Detection
frequencies (%Ds) for the individual pyrethroids were variable among
the dust samples, and ranged from 20 to 67% (Table 2). Cis- and transpermethrin
had the highest %D at 67% with median concentrations
of 244 and 172 ng/g dust, respectively, and an average ± standard
deviation (SD) cis- totrans-permethrin ratio of 1.8 ± 1.1. Cypermethrin