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Urine samples were collected at 3, 6, 9, 12, 24, 48, and 72 h after the start of
spraying for each subject of group 1; at 12, 24, 36, 48, 60, 72, 96, and 120 h for
people in group 2; and at 24, 48, 72, 96, and 120 h for group 3.
Air, gauze, and urine samples were analyzed for deltamethrin and fenvalerate
by gas chromatography (Varian 3700) with a 63 Ni electron-capture detector.
The detection limit was 2 ng/mL hexane for air and gauze samples and
0.2 gIL in a 10-mL urine sample for both urinary deltamethrin and fenvalerate
(Han et al. 1988; Wu et al. 1992). The analysis of deltamethnn metabolite,
dibromovinyl-dimethyl-cyclopropane carboxylic acid (Br2A) in urine was
determined by high-performance liquid chromatography (HPLC; Beckmann
344) (Yao et al. 1992).
To determine the toxic effects of pyrethroids, all participants completed a
questionnaire and were interviewed. A physical examination was also conducted
after pyrethroid exposure. Blood cholinesterase levels were measured
in subgroups lb. 2b, and 2d, before and after spraying.
Nerve excitability in workers spraying deltamethrin
Twenty-four adult male cotton growers from Langfang County, aged 17-57
years, sprayed 2.5% deltamethrin emulsifiable concentrate (EC) diluted
1:1 000 in water for 5 h/day for 3 days in the cotton fields. To assess exposure,
urine samples were collected from 19 of the subjects at 0, 24,48,72, and 120 h
after the beginning of spraying. Deltamethrin was determined by gas chromatography
and its metabolite, Br2A, by HPLC. Median-nerve excitability was
detected with a mobile electrornyograph (Medelec MS 92a), with pairs of
stimuli using a percutaneous technique described by Gilliatt and Willison
(1963) in each member of the exposed group before and after the 3-day
spraying period and 2 days after cessation of exposure. Twenty-nine unexposed
people in Langfang County, aged 17-62 years, were also measured for
median-nerve excitability at 2- and 3-day intervals. The difference in nerve
threshold between two examinations was kept at less than 1.5 mA for each
subject in both groups.
Results
The 573 cases of acute pyrethroid poisoning were classified by specific substance
and by cause (Table 2). The clinical manifestations due to acute
deltamethrin and fenvalerate poisoning, whether occupational or accidental,
were similar. Abnormal facial sensations were obvious first symptoms in
occupationally exposed subjects, whereas accidentally intoxicated patients
displayed more epigastric disorders due to ingestion of pyrethroids.
Symptoms in mild cases included dizziness, headache, nausea, anorexia,
fatigue, listlessness, and muscular fasciculation. Frequent attacks of
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