Characterization of dioxin exposure in firefighters, residents, and chemical workers in the Irkutsk Region of Russian Siberia.

The goal of this study was to characterize body burdens of polychlorinated dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) in three groups of Siberians living in the Irkutsk Region of Russia. These groups included firefighters exposed to a mixture of toxic substances extinguishing a large fire at the Shelekhovo Cable Factory in 1992, chemical workers from the Khimprom chemical plant, and residents living in proximity to large chemical factories in Sayansk and Angarsk. Blood samples from all groups were obtained in the fall of 1998. Dioxin analyses of samples were performed in Germany, Canada, and in a Russian dioxin laboratory in Ufa, Bashkortostan Republic. The average levels of dioxin toxic equivalents (TEQs) are 23.6 parts per trillion (ppt) total TEQ (PCDD/F only) in the disabled firefighters, 25.0 in the non-disabled firefighters, 28.7 in residents, and 45.6 in the Khimprom workers blood. Two workers did have elevated total TEQs of 91.4 and 102.2 ppt. Dibenzofurans and coplanar PCBs substantially contribute to the total elevated TEQ seen here. The average TEQs suggest levels of dioxin exposure in this part of the former Soviet Union not dissimilar to levels measured in industrialized countries of Europe and Northern America.

Levels of dioxins and dibenzofurans in breast milk of women residing in two cities in the Irkutsk Region of Russian Siberia compared with American levels.

The presence of dioxins, dibenzofurans, and polychlorinated biphenyls (PCBs) in human tissue, food, and environmental samples from Russia has been monitored since 1988 as part of a research collaboration between a number of countries including Finland, the United States, Germany, the former Soviet Union, and Canada. Although elevated TCDD and PnCDD levels have previously been found in blood of male and female Russian chemical manufacturing workers and in their children, dioxin levels in the general population have usually been found to be lower than in Americans and Europeans. This study continues earlier work in the Irkutsk region of Russian Siberia, where we report levels of dioxin, dibenzofurans, and PCBs in human milk samples taken from general population women living in the industrialized cities of Angarsk and Usolye-Sibirskoye, near Lake Baikal. Total polychlorinated dibenzo-p-dioxin (PCDD) toxic equivalents (TEQs) compared in this paper for the industrialized regions of Siberia, Ukraine, and the US are similar, ranging from 6.1 to 7 parts per trillion (ppt). Recent 1998 milk samples from Angarsk and Usolye-Sibirskoye have total mean polychlorinated dibenzofuran (PCDF) TEQs of 10 and 21.7 ppt, respectively, with the other industrialized countries ranging from 2.3 to 6.7 ppt. Although dioxin-like PCBs were not measured for the city of Usolye-Sibirskoye (1998), total mean PCDD/F TEQ from Angarsk and Usolye-Sibirskoye (1998) were the two highest levels in this study, with 26.9 and 28.5 ppt, respectively, followed by 1993-1994 Ukraine samples with 24 ppt, 1989 Siberian samples with 13.6 ppt, and 1996 USA with 11.4 ppt total TEQ. In this study, higher levels of dioxins are noted in milk from Angarsk and Usolye-Sibirskoye than found in earlier Russian studies, with mean levels also exceeding 1996 and 1999 US breast milk dioxin levels.

Recent dioxin contamination from Agent Orange in residents of a southern Vietnam city.

Marked elevation of dioxin associated with the herbicide Agent Orange was recently found in 19 of 20 blood samples from persons living in Bien Hoa, a large city in southern Vietnam. This city is located near an air base that was used for Agent Orange spray missions between 1962 and 1970. A spill of Agent Orange occurred at this air base more than 30 years before blood samples were collected in 1999. Samples were collected, frozen, and sent to a World Health Organization--certified dioxin laboratory for congener-specific analysis as part of a Vietnam Red Cross project. Previous analyses of more than 2200 pooled blood samples collected in the 1990s identified Bien Hoa as one of several southern Vietnam areas with persons having elevated blood dioxin levels from exposure to Agent Orange. In sharp contrast to this study, our previous research showed decreasing tissue dioxin levels over time since 1970. Only the dioxin that contaminated Agent Orange, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), was elevated in the blood of 19 of 20 persons sampled from Bien Hoa. A comparison, pooled sample from 100 residents of Hanoi, where Agent Orange was not used, measured blood TCDD levels of 2 parts per trillion (ppt). TCDD levels of up to 271 ppt, a 135-fold increase, were found in Bien Hoa residents. TCDD contamination was also found in some nearby soil and sediment samples. Persons new to this region and children born after Agent Orange spraying ended also had elevated TCDD levels. This TCDD uptake was recent and occurred decades after spraying ended. We hypothesize that a major route of current and past exposures is from the movement of dioxin from soil into river sediment, then into fish, and from fish consumption into people.