Comparison of dibenzodioxin levels in blood and milk in agricultural workers and others following pentachlorophenol exposure in China.

Substantial amounts of sodium pentachlorophenol (Na-PCP) salts have been sprayed in certain areas in central China since the 1960s for control of snail-borne schistosomiasis. A sample of Na-PCP used in the area of concern was analyzed and showed 2,3,7,8-substituted dibenzodioxin (PCDD) and dibenzofuran (PCDF) congeners as well as some non-2,3,7,8-substituted congeners. Dibenzodioxin analysis of two pooled blood samples from 100 persons living in sprayed areas and a pooled sample from 26 individuals who had direct contact with the Na-PCP showed elevations of PCDD/F congeners found in the Na-PCP. Total PCDD/Fs ranged from 631 to 1252 parts per trillion (ppt) lipid in the blood of those exposed to Na-PCP, while two general population age-matched pooled blood samples from 50 persons each had total PCDD/Fs of 147 and 178 ppt. Toxic equivalents calculated with International Toxic Equivalency Factors (I-TEqs) ranged from 9 to 16.3 ppt in the blood samples from exposed persons while the general population blood I-TEqs were 4.8 and 6.4 ppt. A pooled breast milk sample from 50 women living in the sprayed areas was compared with a pooled sample from 50 women living in unsprayed areas. Total PCDD/Fs was low in both exposed and general population samples (134 and 42 ppt lipid, respectively), however, the women living in sprayed areas had considerably higher PCDDs, 129 ppt versus 34 ppt. The mothers exposed to Na-PCP had a I-TEq of 5.4, which was about double that of the mothers from the general population, 2.6 ppt, lipid. Although human PCDD and PCDF tissue levels in China are low compared with those in more industrialized countries, the higher levels in exposed persons are cause for concern.