Analysis of breast milk to assess exposure to chlorinated contaminants in Kazakhstan: Sources of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposuresin an agricultural region of southern Kazakhstan
K. Hooper et al., Analysis of breast milk to assess exposure to chlorinated contaminants in Kazakhstan: Sources of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposuresin an agricultural region of southern Kazakhstan, ENVIR H PER, 107(6), 1999, pp. 447-457
High levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; up to 208 pg/g fa
t) were measured in samples of breast milk collected in 1997 from 64 donors
[41 first-time mothers (primiparae)] living on state farms in southern Kaz
akhstan. TCDD was the major contributor (70%) to the toxic equivalents, mat
ching the congener patterns found in breast milk and serum samples collecte
d in 1994 and 1996 from donors in nearby villages. The highest TCDD levels
were found in state farms adjacent to a reservoir (zone A), which receives
agricultural runoff from cotton fields. TCDD levels in zone A were signific
antly higher than levels in a region more distant (zone B; > 10 miles) from
the reservoir (zone A: mean 53 pg/g, n = 17; zone B: mean 21 pg/g, n = 24;
p = 0.0017). Levels of TCDD in breast milk and animal-derived foodstuffs w
ere 10 times U.S. levels. Body burden and dietary data suggest that exposur
es to TCDD are chronic, environmental, and long term and may be related to
the use of chemicals in cotton agriculture. The data suggest that the most
likely source is the use of cotton defoliants contaminated with TCDD, and t
he most likely pathway for human exposure is via the consumption of contami
nated foodstuffs.