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Impact of - IDL-BNC @ IDRC - International Development Research ...

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Investigations into acute pyrethroid<br />

poisoning in cotton growers<br />

in China<br />

Fengsheng He, Shuyang Chen, Zouwen Zhang, Jinxiu Sun, Peipei Yao,<br />

Yuqun Wu, Shaoguang Wang, Lihui Liu, and Hai Dang<br />

Institute <strong>of</strong> Occupational Medicine,<br />

Chinese Academy <strong>of</strong> Preventative Medicine,<br />

Beijing, People's Republic <strong>of</strong> China<br />

The use <strong>of</strong> pyrethroid insecticides for pest control in China has been<br />

increasing. Acute pyrethroid poisonings have occurred in cotton growers<br />

since 1982. In an epidemiological study <strong>of</strong> 3 113 cotton farmers <strong>of</strong> Gaochen<br />

County, the prevalence <strong>of</strong> acute pyrethroid poisoning was 0.31% in<br />

pyrethroid-exposed sprayers and 0.38% in those exposed to pyrethroidorganophosphate<br />

mixtures; blood cholinesterase levels were normal.<br />

Determination <strong>of</strong> exposure levels by measuring air concentrations and<br />

dermal exposure indicated that dermal exposure is the most important<br />

route <strong>of</strong> absorption. An increase in median-nerve excitability was found<br />

in cotton farmers spraying deltamethrin for 3 days, but there was no<br />

significant correlation with levels <strong>of</strong> urinary deltamethrin or its metabolite<br />

Br2A. Diagnostic criteria for acute pyrethroid poisoning are proposed.<br />

Recommendations are made for preventive measures and safer use <strong>of</strong><br />

pyrethroids by agricultural workers.<br />

Since 1982, the application <strong>of</strong> pyrethroids in cotton-growing areas <strong>of</strong> China<br />

has been increasing. Compared with commonly used broad-spectrum insecticides,<br />

such as organophosphates and carbamates, synthetic pyrethroids are<br />

more powerful on a weight-per-activity basis, yet they metabolize rapidly and<br />

leave virtually no residue in the biosphere. As a result, they are used extensively<br />

to control a wide variety <strong>of</strong> agricultural insect pests. In China, the most<br />

frequently used pyrethroids are deltamethrin, fenvalerate, and cypermethrin.<br />

Pyrethroids were originally classified as compounds unlikely to pose an acute<br />

hazard in normal use. However, evidence from experiments on animals<br />

indicates that deltamethrin and fenvalerate affect both the central and<br />

49

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