Analysis of breast milk to assess exposure to chlorinated contaminants in Kazakstan: High levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in agricultural villages of southern Kazakstan

To assess levels of chlorinated contaminants in breast milk, we measured or ganochlorine pesticides, polychlorinated biphenyls, polychlorinated dibenzo -p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) in breast mil k samples collected in 1994 according to the World Health Organization prot ocol From 92 donors that were representative of regional populations in sou thern Kazakstan. High levels (10-120 pg/g fat) of: 2,3,7,8-tetrachlorodiben zo-p-dioxin (TCDD), the most toxic of the PCDD/PCDF congeners, were found i n breast milk samples from an agricultural region. TCDD was the major contr ibutor (75%) to the international toxicity equivalents of these samples. Th e same distinctive PCDD/PCDF congener pattern was found in 15 breast milk s amples and 4 serum samples collected in 1996 in a follow-up study, and has now been confirmed by three analytical laboratories.