Induction of cytochrome P4501A and endocrine disrupting effects of school incinerator residues.

The emission of the dioxin-like compounds from on-site waste incinerators of seven schools in Kyonggi Province of Korea was evaluated by determination of the cytochrome P4501A(CYP1A) catalytic activity and antiestrogenic activity using cell culture microbioassay. The residue samples were extracted in a Soxhlet apparatus using toluene for 20 hr. The concentrated crude extracts were fractionated with a basic alumina column. Dioxin-like compounds were then extracted. Induction of CYP1A activity in a rat (H4IIE) hepatoma cell line was used as indicator of biological effect of incinerator residues and measured as 7-ethoxyresorufin-O-deethylase (EROD) activities. The EROD activities of fraction II extracts (one of the two extracts) in the H4IIE cells were from 0.044 +/- 0.002 to 4.424 +/- 0.351 ng-TEQ g(-1) (TCDD Toxicity equivalent), showing relatively high inducing capacity. Antisetrogenicity of the extracts was measured as decrease in E2-induced cell proliferation. Most of the extracts showed antiestrogenic activity in MCF7-BUS cell. The TEQ levels of the incinerator residues and the antiestrogenic activities were in good correlation, strongly suggesting that the potent toxic emissions were indeed produced from the on-site school waste semi-incinerators and could cause the antiestrogenicity.