Persistent organic pollutants properties

Sum Chi Lee received her B.A.Sc. and M.A.Sc. in Chemical Engineering from the University of Toronto. She has conducted environmental research at various government organizations and the University of Toronto. Her research activities have included establishing the physical-chemical properties of organochlorines and understanding the sources, trends, and behavior of persistent organic pollutants in the atmosphere of the Canadian Arctic. 

Persistent organic pollutants (POPs) are organochlorine compounds widely used as pesticides and/or industrial chemicals. These chemicals share four common properties highly toxic, persistent, capable of long-range transport and bio-accumulation in the fatty tissues of living... 

Table 17.1. Properties of some persistent organic pollutants...

Sabljic, A., QSAR models for estimating properties of persistent organic pollutants required in evaluation of their fate and risk, Chemosphere, 43, 363-375, 2001. 

In the following sections, the physico-chemical properties and the bioconcentration of selected super-hydrophobic persistent organic pollutants (POPs) such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD),octachlorodibenzo-p-dio-xin (OCDD), Mirex, and Toxaphene in fish and other animals will be discussed. 

Many persistent organic pollutants (POPs) and other environmental contaminants have been associated with immunotoxic effects, but, in most instances, it remains difficult to assign the effects to pure compounds. For example, immunotoxic effects of PCBs in free-ranging harbor seals have been associated with increasing blubber concentrations of PCBsJ34 yet the waters inhabited by these animals are also contaminated with other POPs, including chlorinated pesticides and chlorinated polynuclear aromatic hydrocarbons. Indeed, the PCBs themselves are mixtures of different moieties with varying immunotoxic properties. 

Chemicals that persist (are slow to degrade), bioaccumulate in animals (collect in animal tissue, or organs), and are toxic to humans or animals are especially problematic because their concentrations in the environment increase overtime, increasing the opportunities for exerting their toxic effects. Chemicals with these properties of persistence (P), bioaccumulation potential (B), and toxicity (T) are known as PBTs.The Stockholm Convention on Persistent Organic Pollutants (POPs)— which is designed to phase-out very persistent, very bioaccumulative, and toxic chemicals— reflects the widespread recognition of the risks posed by PBTs (POPs are synonymous with PBTs). 

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