Non- and Mono-ortho Chlorinated Biphenyls

Abstract

Polychlorinated biphenyls (PCBs) are a complex mixture, identified in every component of the global ecosystem. If potential toxicity, environmental prevalence, and potential risk to humans and wildlife are considered, non-and mono-ortho substituted chlorinated biphenyls become extremely important. They resemble 2,3,7,8-tetrachloro dibenzo-p-dioxin (TCDD) in their biological action, causing hepato-, immuno-, reproductive, and dermal toxicities, and inducing mixed function oxidase (MFO) enzymes. This is the basis behind TCDD toxic equivalency (TEQs) as an approach towards risk assessment. Improvements in chromatographic techniques have yielded an array of analytical methods for these congeners that resulted in the determination of coplanar non-ortho and mono-ortho CBs in air, water, soil, and in organisms. Long range trans-hemispheric transportation of these substances in air and ocean currents have been demonstrated. Their contents in commercial PCBs have been studied and their formation during incineration is shown. Long term studies in river sediments demonstrate reductive dechlorination. PCB clearance from animals occurs both by non-metabolic and metabolic routes. Their flux in air, water, and sediments is estimated. OH reactions in the atmosphere is proposed as a principal source of loss along with permanent burial in marine and fresh water sediments.

PCNs, PCDD/Fs, and Non-orthoPCBs, in Water and Bottom Sediments from the Industrialized Norwegian Grenlandsfjords

“…The occurrence and fate of PCBs and PCDD/Fs have been analyzed in many environmental matrices including water, sediments, and biota , . However, although reported data on the distribution of PCNs in the environment is still limited, there are a number of studies that demonstrate their occurrence in sediments, air, and mammals − .…”

Long-Term Dynamics of Persistent Organic Pollutants in Water Bodies of the Aral Sea–Syrdarya Basin

“…According to Agapkina G.I. and Kannan N. [64,65], a wider structural diversity of PCB congeners is a sign that sources of different origins are involved in the pollution of the water body and the watercourse with these toxic compounds. These may include contamination by industrial PCB mixtures, atmospheric transport, and pyrogenic origin, for instance, as a consequence of reed burning, due to industrial and domestic waste incineration processes.…”