14 - Dioxins and Furans

Abstract

The term dioxins refer to chlorinated dibenzo-p-dioxins (CDDs) and furans to chlorinated dibenzofurans (CDFs). CDD or CDFs are not created intentionally, but are produced inadvertently by a number of human activities including chemical manufacturing and incomplete combustion, as well as by natural processes such as forest fires and volcanoes. In this chapter, the physical and chemical properties of CDD or CDFs and the toxicity equivalent (TEQ) methods are reviewed. This chapter describes the historical development of analytical methods and presents some of the pitfalls of using historical data in chemical fingerprinting. It provides an overview of the natural and anthropogenic sources of CDD or CDFs then outlines the general approaches used in forensic studies illustrated with three case studies. Identification of CDD or CDF sources in environmental and biological media is challenging because of low concentrations and associated analytical uncertainties; the potential need to compare data from different laboratories and different methodologies; the presence of multiple sources that are difficult to distinguish, particularly at low concentrations; and the confounding effects of chemical and biological transformations, particularly for airborne sources.