Chapter 36 - Brominated Flame Retardants
Citation:
Kodavanti, Prasada Rao, T. Stoker, S. Fenton, AND M. Curras-Collazo. Chapter 36 - Brominated Flame Retardants. Chapter 36, Ramesh C. Gupta (ed.), REPRODUCTIVE AND DEVELOPMENTAL TOXICOLOGY (3rd edition). Academic Press Incorporated, Orlando, FL, , 691-726, (2022). https://doi.org/10.1016/B978-0-323-89773-0.00036-9
Impact/Purpose:
This book chapter is a very informative treatise on Brominated Flame Retardants with focus on polybrominated diphenyl ethers and new phosphate flame retardants. This chapter covers not only environmental levels and routes of human exposure to these toxicants, but also the human health effects focusing on reproductive and developmental effects. Additionally, the mechanisms (both biochemical and molecular) that underlie the observed toxicities of these chemicals were given due consideration. Some of the key biochemical endpoints such as enzymes, metabolites and cellular macromolecule (protein, lipids and nucleic acids) changes serve as biomarkers of effect upon exposure to the above-mentioned toxicants. This book chapter provides valuable insights to employing these biomarkers for toxicity studies. This information will be of use when dose-response studies are carried out for risk assessment purposes. The revised narrative in this chapter is supported by recent literature to make the knowledge base current.
Description:
This chapter covers both developmental and reproductive effects of brominated flame retardants (BFRs) with emphasis on polybrominated diphenyl ethers (PBDEs). BFRs belong to a large group of organohalogen chemicals. They are highly persistent, bioaccumulative, and cause adverse effects in humans and wildlife. Although some BFRs are banned or voluntarily withdrawn from usage by the manufacturer, emerging and existing BFRs continue to be used in industrialized countries. Because of the widespread use and large quantities of these chemicals in consumer products and household items, indoor contamination is proposed to be a significant source of human exposure. Other exposure routes are oral—both via breast milk, fat-containing foods, hand-to-mouth activity, etc. Recent epidemiological studies clearly indicated that BFRs affect human health. The human health effects include cryptorchidism, alterations in thyroid hormone homeostasis, reproductive effects, and reduced development of children at school age that include psychomotor development index and IQ performance. Studies have also indicated that the infant daily exposure dose of PBDEs due to inhalation, accidental oral ingestion, and dermal absorption of house dust was significantly higher than that of the adults. Many rodent studies have confirmed that developmental exposure to these compounds should be limited to protect human health. Studies in rodents indicated that several BFRs are developmental neurotoxicants affecting the nervous system growth and function. Several studies have also confirmed that the BFRs are indeed endocrine disruptors, with the potential to disrupt male and female reproductive development and adult reproductive function by having antiandrogenic actions (males) and by altering steroidogenic activities. This has been demonstrated in several in vivo studies using rodent models and by in vivo systems to determine effects on receptor binding (AR and PXR) and on steroidogenesis. These potential modes of action may be relevant to humans. This is incredibly important to consider as there have been several reports of adverse health consequences associated with increased PBDE exposure in humans in the last few years. Further research is needed to determine the long-term adverse consequences of exposures to the BFRs described herein as well as a number of emerging replacement chemicals coming onto the market, as these compounds are known to bioaccumulate and can be transplacentally and lactationally transferred.
