Abstract
In pest control operations, organophosphorus compounds (OP) have been sprayed as insecticides. Blood cholinesterase (ChE) activities and urinary alkylphosphate levels were measured for both OPsprayers (n=102) and non-sprayers (n=35) in pest control companies, and the relationship between the analytical results and spraying conditions was investigated.
Plasma ChE activities of the OP-sprayers and of the non-sprayers, as well as blood cell ChE activities of the OP-sprayers, were significantly lower than those of employees of chemical factories who served as controls (n=103). Urinary alkylphosphates were not detected in the controls at all but were detected in 83% of the sprayers and in 57% of the non-sprayer employees of pest control companies.
A significant negative correlation (r=-0.34, n=137, p<0.01) between the plasma ChE activities and urinary total alkylphosphate levels was observed in employees of pest control companies. In the case of the employees whose urinary total alkylphosphate levels were 0.1μmol/g creatinine or more, the plasma ChE activities were 25% decreased compared to the control group.
The OP-sprayers showed significantly higher urinary total alkylphosphate levels than the nonsprayers. The OP-sprayers were further divided into two groups. One was sprayers engaged in both cockroach- or fly-control and termite-control operations (sprayers I, n=54) and the other was sprayers engaged in only cockroach- or fly-control operations (sprayer II, n=48). The sprayers I group showed higher urinary diethylphosphate and diethylthiophosphate levels than the sprayers II group, and, inversely, the sprayers II group showed higher urinary dimethylphosphate and dimethylthiophosphate level than the sprayers I group. However, a difference was not observed between the total alkylphosphate levels of sprayer groups I and II.
The levels of urinary alkylphosphates of the OP-sprayers were decreased with the number of days after the last spraying; the workers who sprayed 4 days or more before showed the same urinary levels as the non-sprayers. The passage of time did not affected not only blood cells but also plasma ChE activities.
These results indicate that levels of urinary alkylphosphates reflect recent OP-spraying qualitatively and quantitatively and that urinary alkylphosphate levels are useful as an index of exposure to OP.
