Persistent Organic Pollutants (POPs) are organic compounds of mainly
anthropogenic origin posing a huge threat to human health and the ecosystem. Though
the production and intended use of major POPs are banned by Stockholm Convention,
still some POPs are being used in most developing countries around the globe.
Although, environmental levels of some POPs, such as Polychlorinated biphenyls
(PCBs) have declined, newly added POPs in the list of conventions, such as
Polybrominated Diphenyl Ethers (PBDEs), Perfluorooctanesulfonate (PFOS) have
emerged as new challenges. Exposure to POPs has been associated with a wide
spectrum of health effects, including developmental, carcinogenic immunologic,
reproductive, and neurotoxic effects. It is of major concern that the neurotoxic effects
of some POPs have been observed in humans at low environmental concentrations.
This chapter focuses on various POPs like PCBs, PBDEs, and PFOS as a representative
chemical class of POPs and discusses the possible modes (s) of action for the
neurotoxic effects with an emphasis on comparing dose-response and structure-activity
relationships (SAR) with other structurally related chemicals. There are sufficient
epidemiological and experimental studies carried out in different parts around the globe
showing that PBDEs and PFOS exposure is associated with motor and cognitive
deficits in humans and animal models. Several potential mechanisms were presumed
for PBDEs and PFOs induced neurotoxic effects and alteration in neurotransmitter
systems. Among them, the intracellular signaling processes and hormonal imbalance
impacting the activity of thyroid hormone were reported as predominant. All these
potential mechanisms are discussed in detail in the chapter. In addition to this, SAR
will be highlighted for examining the toxicity of other relevant and structurally similar
POPs to assess if they have a common mode(s) of action. Potency factors for several
other POPs will also be described focusing on their effects on intracellular signaling
processes and enzymatic activity and cell signaling pathways. This chapter is a
comprehensive review, describes the alteration of enzymatic pathways and their
associated toxicity at the biochemical level in different models for environmentally
relevant POPs.
Keywords: Neurotoxicity, Persistent Organic Pollutants, Polychlorinated Biphenyls
(PCBs), Polybrominated Diphenyl Ethers (PBDEs), Perfluorooctane Sulfonate(PFOS),
Structure-Activity Relationships (SAR), Thyroid hormones.
