The international toxicity equivalency factor (I‐TEF) method for estimating risks associated with exposures to complex mixtures of dioxins and related compounds∗

Partitioning of dioxins (PCDDs/Fs) in ambient air at urban residential locations

“…The molecular structure of PCDDs comprises two benzene rings connected by two oxygen atom bridges, whereas that of PCDFs consists of two benzene rings joined by a carbon bond and an oxygen bridge. Although there are 210 PCDD/F congeners with similar structures, their toxicity varies greatly according to the degree and position of the chlorine substitution (Kutz et al 1990). …”

“…They may also undergo various degradation processes in the atmosphere (Kim et al 2001a, b). Among the total 210 PCDD/Fs, a total of seventeen 2,3,7,8 substituted congeners are known to be toxic to many laboratory animals (Kutz et al 1990) and toxic to human via exposure pathways such as inhalation, dermal contact, and ingestion (Jin et al 1995;de Wit 2002;Fiedler 2003). In most cases they occur as a result of manmade activities such as waste incineration, automotive emissions, chemical production processes, and from steel works.…”

A Simplified Determination Method of Dioxin Toxic Equivalent (TEQ) by Single GC/MS Measurement of Five Indicative Congeners

“…One of them is TEQ estimation using indicative congener(s), whose concentration has a high correlation with TEQ. Fiedler et al 8 reported an intriguing observation that the concentration of 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) was proportional to the TEQ, based on the international TEF, 9 of PCDDs/PCDFs in stack emission gas samples, and proposed a conversion factor from the concentration of 2,3,4,7,8-PeCDF to the TEQ. There were some parallel studies for combustion by-products.…”

Abundance and sources of ambient dioxins in Hong Kong: A review of dioxin measurements from 1997 to 2001

“…A group of 17 congeners with chlorine atoms at 2, 3, 7, and 8 positions are of particular concern due to their toxicity (Kutz et al, 1990). Dioxins in ambient air have many sources, such as incomplete combustion activities (e.g., incineration of municipal, clinical, household and chemical wastes, open burning, and landfill fires) and alkali chlorine chemical-related industries (Rappe, 1992;Lee et al, 1999;Lohmann et al, 1999;McKay, 2002).…”