ABSTRACT
Two important reports related to the high, dioxinlike toxicity of sulphur-analogues of polychlorinated dibenzofurans have been published in recent years (Nakai et al. 2004; Hosomi 2005). In prior works, Kopponen et al. (1994) analysed the influence of three organosulphur compounds: 2,3,7,8-TeCTA (tetrachlorothianthrene) – sulphur analogue of tetrachlorodibenzodioxin, 2,3,7,8-TeCDT (tetrachlorodibenzothiophene) and 3,3’,4,4’-TeCDPS (tetrachlorodiphenylthioether) – sulphur analogue of tetrachlorodiphenylether, on the induction of CYP1A1 gene expression, which was measured as an activity of aryl hydrocarbon hydroxylase (AHH) and ethoxyresorufin-O-deethylase (EROD) in liver cells of Hepa-1 mice. Significant differences between 2,3,7,8-TeCDT and analysed sulphur analogs in EROD and AHH activity were observed. They found EC (50) values as follows: 2,3,7,8-TeCTA - 700 [pM]; 2,3,7,8-TeCDT – 7500 [pM]. However, they did not observe the response for 3,3’,4,4’-TeCDPS. Calculated Response Equivalency Potencies (REP) for these compounds were respectively: 0.011; 0.001 and 0. Moreover, the value of the REP factor (0.00425) was estimated by Giesy for a synthetic mixture of PCDT congeners in the H-4IIE rat liver cells (Giesy et al. 1994).
