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Ms No. 02858: Organohalogen Pollutants and Human Health
Kodavanti, P., B. Loganathan, K. Senthil Kumar, AND K. Sajwan. Ms No. 02858: Organohalogen Pollutants and Human Health. Chapter 0, Biomedical Sciences. ELSEVIER, AMSTERDAM, Holland, 1:1-7, (2014).
It is axiomatic that human activities change the quality of the environment on a global scale, which can adversely affect life on earth. A prototypical example of such environmental damage and harmful biological effects is that caused by persistent human-made chemicals, particularly organohalogen compounds. Organohalogens are organic compounds that contain chlorine, bromine, fluorine atoms (named chlorinated, brominated, and fluorinated compounds, respectively) ( Figure 1, Figure 2, Figure 3, •and Figure 4). Due to their extreme persistence in the environment, bioaccumulative nature, and long-term health effects in humans, some organohalogen compounds such as polychlorinated biphenyls (PCBs, an industrially versatile compound), insecticides such as DDTs, HCHs (BHC), chlordane (CHLs), and industrial byproducts such as chlorinatedlbrominated dioxins/dibenzofurans are well-known global environmental contaminants. Although the use of some of these synthetic chemicals have been banned or severely restricted in most developed countries more than four decades ago, these organohalogens are still found in almost all components of the global ecosystem and pose a threat to life on earth. Following the ban on their production and use, residue levels of those organohalogens have declined, but in some cases at a relatively slow rate. Nevertheless, new organohalogens continue to be discovered in the environment. Perfluorinated compounds (PFCs), polybrominated diphenyl ethers (PBDEs), triclosan, triclocarban, tetrabromobisphenol A (TBBPA) and hexabromocyclododecanes (HBCDs) are widely used in a variety of industrial and consumer products and are considered emerging persistent global environmental pollutants ( Figure 2, Figure 3 and Figure 4). The historical background of the organohalogens, their physicochemical properties, environmental contamination, human exposure, and effects on human health are described in this article with particular focus on chlorinated, brominated, and fluorinated compounds.
During the past century, a vast number of organic chemicals have been manufactured and used in industrial, agricultural, public health, consumer products and other applications. The organohalogens, including chlorinated, brominated and fluorinated compounds, are ubiquitous in the environmental landscape and biota; with human exposures occurring through multiple pathways such as direct skin contact, inhalation, drinking water, and food. Exposure to chlorinated compounds is known to cause reproductive, neurotoxic, immunotoxic, endocrine, behavioral, and carcinogenic effects in both wildlife and humans. Polybrominated diphenyl ethers (PBDEs), the perfluorinated chemicals (PFCs), triclosan, triclocarban, tetrabromobishphenol A (TBBPA) and hexabromocyclododecane (HBCD), are considered as emerging new environmental pollutants. Based on their current and probable future use and their persistent chemical properties, it can be predicted that human exposure to these compounds will continue to increase. The health effects of these emerging chemical pollutants are of concern for the twenty-first century and beyond.