ORGANOPHOSPHORUS FLAME RETARDANTS (OPFR): NEUROTOXICITY

Organophosphorus flame retardants (OPFRs) are used as additives in plasticizers, foams, hydraulic fluids, anti-foam agents, and coatings for electronic components/devices to inhibit flames. These chemicals were developed and used as flame retardants because of environmental and health concerns of previously used brominated and chlorinated flame retardants (FRs). OPCFRs are divided into five main groups: organophosphates, organophosphonates, organophosphinates, organoposphine oxide, and organophosphites. Most of OPFRs are organophosphate esters that are further classified into the following five groups: 1. Aliphatic, 2. Brominated aliphatic, 3. Chlorinated aliphatic, 4. Aromatic-aliphatic, and 5. Aromatic phosphates. These OPFRs have the following neurotoxic actions: 1. Cholinergic Neurotoxicity, 2. Organophosphate-Induced Delayed Neurotoxicity (OPIDN), and 3. Organophosphate-Induced Chronic Neurotoxicity (OPICN) in addition to being endocrine disruptors. OPFRs have very low cholinergic neurotoxicity and this effect does not pose significant health hazards to adults or children. On the other hand, some OPFRs have shown to cause OPIDN that is a delayed central-peripheral axonopathy, characterized by neuronal cell death of the lower brain regions, spinal cord and peripheral nervous systems, leading to long-term neuronal injury. OPICN is characterized by neuronal cell death in the cortex, hippocampus campus and cerebellum and spinal cord. Finally, OPCFRs act as endocrine disrupters, that affect many functions of the body such thyroid glands and reproductive functions, and may be involved in the development of diabetes and cancer. Residues of these OPCFRs are widespread in the environment, home and workplaces. These chemicals adversely affect human health, especially for vulnerable population such as the elderly, pregnant women, fetuses, and children. Because some OPFRs cause neuronal cell death in the brain and spinal cord that do not repair as well as act as endocrine disrupters they may lead to permanent functional deficits such obesity, memory impairment, decreased motor skill and even more serious diseases such as diabetes and cancer. Because recent reports have accredited FRs for significant decrease in building fires, it is important to balance the risk and benefits of FRs and to use only the safest available FRs including OPFRs.