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peripheral nervous systems; acute poisoning in mice and rats was manifested
as choreoathetosis and convulsion (Vijverberg and Bercken 1982). Earlier
studies suggested that industrial exposure to pyrethroids induced only local
effects on human skin. After exposure, abnormal facial sensations described
as burning, itching, or tightness and erythema or miliary red papules persist
(Le Quesne and Maxwell 1980; Kolmodin-Hedman et at. 1982; Tucker and
Flannigan 1983; He et al. 1988).
No clinical data about acute pyrethroid poisoning in occupationally exposed
subjects had been reported until several incidents of acute intoxication
occurred among farmers spraying deltamethrin and fenvalerate in China in
1982 (He et al. 1989). Having been told that these new insecticides were
"nontoxic," the cotton farmers handled them without any safety precautions.
More than 300 cases of acute pyrethroid poisoning occurred in 1982, when
pyrethroids were first introduced and extensively used in cotton-growing
areas of China, such as Hebei, Jiangsu, Hubei, Liaoning, Shandong, and Henan
provinces. It is now evident that the compounds do have an inherent neurotoxicity.
Although the use of pyrethroids as pesticides is increasing, little research has
been done on their acute and long-term effects on man. From 1987 to 1989,
investigations were carried out on the diagnosis of acute pyrethroid poisoning,
the prevalence of occupational pyrethroid intoxication in cotton growers,
and the assessment of risks to people spraying under defined conditions (by
measurement of exposure and median-nerve excitability). The aim of these
studies was to reduce the risks associated with the use of pyrethroids by cotton
farmers in China.
Methods
Diagnosis of acute pyrethroid poisoning
Between 1983 and 1988,573 cases of acute pyrethroid poisoning were reported
(He et al. 1989). We reviewed the case histories and medical records of these
patients and interviewed some of them.
Epidemiology
To assess the extent of the problem of pyrethroid poisoning in cotton growers,
an epidemiologic survey was conducted in Gaochen County, Hebei Province,
from June to August in 1987 and 1988. The procedures established by the
World Health Organization (WHO 1982) were followed. The criteria derived
from the diagnosis investigation, above, were used to classify patients. Eight
villages, containing 3 390 families (total population of 19 692) in Gaochen
County were identified as clusters for sampling. A total of 3 113 adults, who
were exposed to pyrethroids during spraying, were studied.
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