Life Sciences Research on Effect of PCBs in Water Systems

Introduction
Polychlorinated biphenyls (PCBs) are among the most toxic persistent organic pollutants (POPs). POPs degrade very slowly and have the tendency to accumulate in organisms and be magnified up the food web and thus persist for a long time in the environment and cause serious ecological damage. Its massive production and use for almost a century since its commercialization in 1929 has left about 1.7 billion tons or more, circulating in the environment, some of which are still in use. (ATSDR, 2000 and 2014)
PCBs are very much inert and chemically stable. PCBs became very attractive for industrial applications for their longetivity. It is resistant to hydrolysis, oxidation and temperature changes. Its non-flammability and dielectric properties also contributed to its widespread use. It had been incorporated in various products as a coolant, dielectric and insulating components in electrical equipment such as capacitors, transformers, motors, magnets, liquid-filled electrical cables and circuit breakers. It has also been added in inks, construction materials, paints, sealants, adhesives, textiles, plasticizers, hydraulic fluids, lubricating oils, and pesticides. Having been spread with the advent of power supply, and being found in all electrical appliances and modern architecture, PCBs have made its mark in modern living. (Füll, 2001; ATSDR, 2000 and 2014)
PCBs come in the form of mixtures of up to 209 congeners. Though most of PCB congeners are not that toxic, a number of PCBs are very similar in structure to the most toxic chemicals known – be polychlorinated dibenzo-p-dioxin (PCDDs) and polychlorinated dibenzofurans (PCDFs). PCB materials also often contain impurities of dioxins and furans. The process of manufacturing PCBs entails side production of these toxic chemicals during pyrolysis. When the material is heated at temperatures of ____, polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are produced. This could also happen during incineration for waste disposal and during fire incidents. (ATSDR, 2000 and 2014)
Mono-ortho-substituted and non-ortho PCBs have phenyl rings that can rotate and adopt a coplanar configuration similar to PCDDs and PCDFs. Despite their resistance to chemical reactions, being similar in shape and polarity to certain biological ligands makes it possible for them bind to certain bodily enzymes having the AL-receptor and disrupt molecular cell signaling. Being non-biodegradable, these are hence retained by the enzyme once bound, thus the enzyme becomes perpetually turned on or off depending on the function of the ligand. This leads to chronic dysfunctions and complications. (ATSDR, 2000 and 2014)
PCB manufacturing had been banned in the USA since 1979 because of its environmental and health toxicity. Monsanto, the originator and major producer of the most commercialized PCB, Aroclor, stopped its production in 1977. They were responsible for about 99% of PCB production of the United States and that accounts for about half of the world supply of PCBs. (ATSDR, 2000 and 2014)
At the peak of PCBs popularity, massive losses in wildlife, agriculture and food industry happened worldwide due to intake of PCBs from contaminated water...