136677-10-6

Basic information

• Product Name: PCDFS
• Synonyms: PCDFS;Dibenzofuran, chloro derivs.
• CAS NO: 136677-10-6
• Mol File: 136677-10-6.mol
• Article Data: 0

Chemical Properties

• Appearance: /
• CAS DataBase Reference: PCDFS(CAS DataBase Reference)
• NIST Chemistry Reference: PCDFS(136677-10-6)
• EPA Substance Registry System: PCDFS(136677-10-6)

Safety Data

• Hazardous Substances Data: 136677-10-6(Hazardous Substances Data)

Usage

Description

Polychlorinated dibenzofurans (PCDFs) are a group of 135 aromatic congeners with a basic structure that can have one to eight chlorine atoms substituted on the phenyl rings. The degree of toxicity of individual congeners is determined by the position of the chlorines on the rings, with the most toxic members being the planar, coplanar, or nearly planar compounds where at least three or four lateral positions are occupied by chlorines, such as the 2,3,7,8-tetrachlorodibenzofuran. Their chemical inertness tends to increase with chlorination.

Uses

PCDFs have no commercial use and are not deliberately produced by the industry. However, small amounts of a few congeners have been synthesized in the laboratory for research purposes. PCDFs are usually present in the environment and in tissues together with polychlorinated dibenzo-p-dioxins (PCDDs) and other chlorinated aromatic compounds. When their presence is determined in the environment, the results are often reported as toxic equivalencies (TEQs) based on toxic equivalency factors (TEFs). Toxicity values are assigned to the congeners of PCDD/Fs relative to the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The sum of all congener TEQs in a specimen (total TEQ) can be used to compare dioxin-like activity among specimens. Most of the research on structure-activity relationship has been done with TCDD, focusing on their binding and activation of the aryl hydrocarbon receptor (AHR), an initial but insufficient step in the development of TCDD-type toxicity.

Toxicity evaluation

PCDFs are lipid soluble and present in water in extremely low concentrations. They may contaminate surface water and groundwater in areas with point sources. They usually adhere to soil or sediment particles. Their presence has not been reported in municipal drinking water. PCDD/Fs were determined in samples of archived surface soils collected in the early 1880s, in contemporary surface soils, and in archived subsurface soils collected in 1870/1880 and stored in Rothamsted experimental station in Lancaster, UK PCDFs were detected in most samples. The homolog compositions of PCDFs in earlier soils were similar to patterns in more recent soils, suggesting that similar sources of atmospheric emissions of PCDFs are operating currently as in the past in Europe. The homolog pattern, in samples from Thailand and Australia were different.