You are here:
PCBs, PBBs and Brominated Flame Retardants
Kodavanti, P. AND B. Loganathan. PCBs, PBBs and Brominated Flame Retardants. 1Chapter 25, R. C. Gupta (ed.), Biomarkers in Toxicology. Elsevier B.V., Amsterdam, Netherlands, , 433-450, (2014).
This chapter introduces selected organohalogen chemicals such as polychlorinated biphenyls (PCB5), polychiorinated biphenyls (PBBs), and brominated flame retardants (BFRs) with emphasis on the background, physicochemical properties, environmental levels, health effects and possible modes of action. Since the focus of this chapter is on biomarkers, three well-known mechanisms are postulated as biomarkers of exposure and effect. Thyroid hormone disruption, perturbed calcium homeostasis and kinase signaling and induction of cytochrome-P450 enzymes are described in detail as biomarkers of exposure and effect of PCBs, PBBs and BFRs in exposed organisms. Although there have been other biochemical effects reported with these chemicals, only these three pathways were discussed in this chapter. Further research is needed in order to identify specific biomarkers of exposure and effect for these grdups of chemicals.
Polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), and brominated flame retardants (BFRs) belong to a group of chemicals known as organohalogens. Organohalogens are organic compounds that contain chlorine, bromine or fluorine atoms and the molecules are named as chlorinated, fluorinated, or brominated hydrocarbons, respectively. These compounds share common characteristics such as persistence in the environment, bioaccumulation in living organisms, long-range transport beyond the geographical regions of their use, and long-term health effects in humans. Even though some of these compounds (e.g. PCBs and PBB5) have been banned or have severely restricted use in developed countries for more than three decades, these compounds are still found in every component of the global ecosystem and poses a threat to human health (Kodavanti, 2005 Kodavanti et al., 2008). Following the ban on production and usage, levels of regulated organohalogens have declined in the environment (Loganathan and Lam, 2012). However, newly discovered organohalogens such as brominated flame retardants (BFR5) take their place and continue to be developed for commercial use. BFRs are widely used as flame retardants in a variety of commonly used consumer products and are considered to be emerging chemicals of concern with regard to human health and sustainability of the ecosystem (Guo etal., 2012). This chapter focuses on physicochemical properties, environmental contamination and human exposure, health effects, mode of action with particular emphasis on biomarkers of exposure and effects for two well-known and already regulated persistent chemical groups such as PCBs and PBBs as well as the emerging persistent chemical group such as BFRs (which are partially regulated).
Record Details:Record Type: DOCUMENT (BOOK CHAPTER)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LAB
TOXICOLOGY ASSESSMENT DIVISION