Multiroute exposure assessment and excretion of urinary metabolites of fenitrothion during manual operations on treated ornamental plants in greenhouses

The results of environmental and biological (five subjects) monitoring of e xposure to fenitrothion during manual operations on treated ornamental plan ts in greenhouses are reported. Urinary excretion [GM (GSD)] of alkylphosph ates [dimethylphosphate (DMP) + dimethylthiothosphate (DMTP)] (nmol/g creat ) was 244.8 (1.8), 174.0 (2.0), and 354.4 (1.6) respectively, on the first (Monday), third (Wednesday), and fifth (Friday) days of work. These levels were not significantly higher than those recorded in a control group (21 su bjects) in which urinary excretion [GM (GSD)] of DMP + DMTP was 102.8 (4.2) nmol/g creat. Air concentrations of fenitrothion (nmol/m(3)) ranged from 4 5.5 to 81.2 on Monday, 17.3 to 27.1 on Wednesday, and 9.7 to 19.1 on Friday . Dose estimates showed that the respiratory-absorbed doses of fenitrothion accounted, on the average (GM), for 94.7%, 93.1%, and 91.5% of the total a bsorbed dose on Monday, Wednesday, and Friday, respectively. Multiple regre ssion analysis showed a significant correlation (r(2) = 0.595) between urin ary excretion of DMP + DMTP, respiratory-absorbed dose, and skin-absorbed d ose, estimated on Monday and Wednesday. Total estimated absorbed doses did not exceed the acceptable daily intake for fenitrothion, Serum and erythroc yte cholinesterase activities were not significantly different before and a fter exposure.