Citation:

Kodavanti, Prasada Rao, M. Valdez, J. Yang, M. Curras-Collazo, AND B. Loganathan. Chapter 37 - Polychlorinated biphenyls, polybrominated biphenyls, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans. Chapter 37, Ramesh C. Gupta (ed.), REPRODUCTIVE AND DEVELOPMENTAL TOXICOLOGY (3rd edition). Academic Press Incorporated, Orlando, FL, , 727-758, (2022). https://doi.org/10.1016/B978-0-323-89773-0.00037-0

Impact/Purpose:

This book chapter is a very informative treatise on PCBs, PBBs, PCDDs and PCDFs. Not only it emphasizes the 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:

Polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) belong to a group of compounds that are structurally related and are environmentally and biologically persistent. These chemicals have a tendency to bioaccumulate and biomagnify in the food chain. Residues of these chemicals have been detected in remote areas of the world and in a variety of animal species, including humans. Exposure to these chemicals has been linked to a broad spectrum of effects. Fetal and early developmental exposures are particularly sensitive and can have more profound and irreversible outcomes when compared to adult exposure. Latent effects of early exposures include, but are not limited to, depressed circulating thyroid hormone levels and abnormal thyroid cytology; developmental effects of the heart, palate and kidney; delayed cognitive development; altered sensory and motor abilities; and reproductive impairment and compromised neuronal function. Although AhR activation has been attributed to several dioxin-like coplanar compounds, some PCBs that are noncoplanar in nature seem to exert their toxic effects through different mechanisms including calcium signaling, oxidative stress, thyroid hormone perturbations, and neurotransmitter imbalance. While certain congeners and isomers can pose a very serious threat to the health of animals and humans, environmental exposure situations are generally such that risks of health effects are generally low. The most significant problem by these compounds involved in accidental poisoning via food supply or consumption of contaminated food from contaminated areas. Additionally, there are areas of the environment that are heavily contaminated by these chemicals because of past industrial activities. Animals and humans residing in or near contaminated locations certainly are at risk of serious health effects. Efforts must continue to reduce exposure to protect wildlife and humans. The best way to accomplish is to modernize technological processes to prevent the release of these chemicals into the environment.

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