Toxicity ofdipterex: afield study

Thisstudy summarises historical surveillance datacollected from1977to1982andthe results ofafield study conducted thereafter (1983-4) ina dipterex packing workshop. Thefindings suggest that bothairborne dipterex anddermal contamination contribute totheinhibition ofblood cholinisterase (ChE)andthat casesofpoisoning inhotseasonscan beattributed mainly todermal absorption. Atalevel of05mg/m3, dipterex isshowntolead toa mildbutappreciable inhibition ofChEactivity. Theresults also indicate thatbloodChEmonitoring was sensitive bothforlong termandshort termexposed workers. Asa result, therecommendation thatthemaximumallow- able concentration forairborne exposuretodipterex berevised to05mg/m3, can beregarded at providing onlyforrelative safety. Dipterex (trichlorifon), oneofthecommonor- ganophosphorous insecticides, hasbeenwidely used forabout30years. Inthepastdecade field studies havebeendirected atexploring anychronic effects andverifying thepresent maximumallowable con- centration (MAC).1-4 Previous workperformed by this groupsuggested thatchronic toxic effects on worker's health exist belowthepresent MAC (1mg/m3), andtherefore alowering to05mg/m3 was recommended.4 Since sucharecommendation needs support fromstudies inwhichworkers experience different exposure concentrations, weconducted the present study inthedipterex packing workshop, Shanghai pesticide factory, inwhich average air con- centrations historically werearound theMAC.This plant offered asuitable site forfurther study ofthe recommended revision inthevalue fortheMAC as well asstudy ofthetoxicity ofdipterex atlowex- posure concentrations.