PESTICIDE APPLICATION AND INCREASED DIOXIN BODY BURDEN MALE AND FEMALE AGRICULTURAL-WORKERS IN CHINA

Large amounts of the powerful pesticide sodium pentachlorophenol (Na-P CP) salt have been sprayed over vast areas in central China to control schistosomiasis, a parasitic disease of epidemic proportions. Approxi mately 6000 tons of Na-PCP are produced in China annually. Dioxins, a class of toxic, persistent compounds, art found as impurities in comme rcial Na-PCP products. These contaminants are released into the enviro nment and significantly contribute to human exposure to dioxins in Chi na. This study was carried out to determine dioxin levels in environme ntal and human tissue samples from one schistosomiasis area to evaluat e the health risks associated with exposure to Na-PCP. Na-PCP pesticid e was applied in 1972, 1973, and again in 1978. A total of approximate ly 454 tons and 902 tons of 5-ppm Na-PCP in water were sprayed over la rge land and lake problem schistosomiasis areas, respectively. The gro ups studied were (1) sprayers or handlers of Na-PCP, (2) persons livin g in the sprayed areas, and (3) persons living in unsprayed areas 300 km north of the sprayed lake located in a city in the Jiangxi province . Individual whole-blood and breast-milk samples were collected and la ter pooled for dioxin analysis. Also, a sample of commercial Na-PCP wa s collected. In addition, sediment samples from the lake where Na-PCP was sprayed were collected from four different sites and one control s ample was collected from a non-schistosomiasis area. All of the sample s were analyzed by high-resolution gas chromatography/mass spectrometr y. A sample of Na-PCP used in schistosomiasis regions was analyzed and levels of 2,3,7,8-substituted dibenzodioxin (PCDD) and dibenzofuran ( PCDF) congeners were measured. in addition, the international dioxin t oxic equivalent (I-TEQ) value of this sample was calculated. Total I-T EQ of 162 parts per billion (ppb) was found in the Chinese Na-PCP prod uct. A pooled breast-milk sample from mothers, female agricultural wor kers who were born in the schistosomiasis areas where large amounts of Na-PCP were sprayed, had an I-TEQ of 5.4 parts per trillion (ppt), li pid, which was about double that of mothers from control regions, wome n born in areas not sprayed with Na-PCP (2.6 ppt, lipid). The dioxin I -TEQ values in human blood ranged from 9.0 (subjects 15 to 19 years of age) to 16.3 ppt, lipid (subjects 35 to 70 years of age) in the whole -blood samples from Na-PCP exposed persons, whereas the general popula tion's whole-blood I-TEQs were 4.8 and 6.4 ppt, lipid respectively. Th e PCDD/F congener distribution patterns in four sediment samples from schistosomiasis areas were similar to that of Na-PCP. By comparison of specific ''fingerprint'' congeners (higher chlorinated dioxins and th e closely related dibenzofurans) in Na-PCP, human tissues, and sedimen t samples, we conclude that the chemical pesticide Na-PCP is a source of environmental and human dioxin exposure in the Chinese schistosomia sis area studied. Although human PCDD/F tissue levels in China are low compared with those in more industrialized countries, the elevated I- TEQ levels in exposed persons are cause for concern.