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RESEARCH PRODUCT

Polychlorinated Dibenzothiophenes (PCDTs), Thianthrenes (PCTAs) and Their Alkylated Derivatives

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Polychlorinated dibenzothiophenes (PCDTs) and polychlorinated thianthrenes (PCTAs) are interesting compounds due to their structural similarity with polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs). PCDTs are sulfur analogues of PCDFs and PCTAs are sulfur analogues of PCDDs. PCDTs and PCTAs are probably formed by processes similar to the formation of PCDFs and PCDDs. PCDTs were first detected in the environment in 1986. Since then PCDTs have been analyzed in samples from combustion and metallurgy, sediments, pulp mill effluents, and in aquatic biota. Combustion and metallurgy seem to be the major sources of PCDTs in the environment. PCDTs and PCTAs are analyzed by different gas chromatographic/mass spectrometric (GC/MS) methods. Several model compounds of PCDTs and PCTAs have been prepared for environmental and toxicological purposes. However, due to lack of labeled or/and pure PCDT and PCTA standards, the environmental concentrations, until now, are generally calculated using labeled 2378-TeCDD as an internal standard. Then it is supposed that the MS response of PCDTs and PCDDs is equal. Toxicological studies have shown that the replacement of oxygen atoms by sulfur greatly decreases the AHH/EROD inducing potency of PCDTs and PCTAs compared to that of PCDFs and PCDDs. Anyhow, in vivo studies have shown that PCDTs and PCTAs possess some kind of dioxin type biological activity.