PCBs: A Pervasive Threat to the Environment and Mankind
Polychlorinated biphenyls, more commonly known as PCBs, have generated an extraordinary amount of research. This research, in large part, has dealt with the dangers associated with the use of PBCs. The research has demonstrated, quite persuasively, that PCBs present a pervasive and interconnected set of multifaceted dangers to ecological systems, food chains, and human beings. More troubling, given the tremendous resistance of PCBs to degradable processes it has proven very difficult to satisfactorily remove or otherwise moderate the effects of PCBs already present in the environment and the food chain.
Some scholars, frighteningly, have even posited that PCBs have affected intergenerational transmissions of genetic traits. In order to better understand the seriousness of the PCB problem this essay will define PCBs, explain where they are found in the environment, explained the serious threats to humans, and discuss why solutions have been rather difficult to find. As an initial matter, in order to understand the pervasive effects of PCBs, it is necessary to define the complex and varied types of PCBs; to be sure, PCBs refer to a group of compounds rather than an individual compound as such.
“The family of chemicals known as polychlorinated biphenyls (PCBs) were first synthesized just before the start of the twentieth century and came into wide industrial use starting in the 1930s. PCBs are a large family of chemicals, with 209 possible “congeners,” or chemical variants. The congeners vary slightly in molecular shape, how many chlorine atoms are attached to the molecule, and where the chlorine atoms are attached. The 209 PCB congeners differ in their toxicity to people and other animals, but the details of how and why are not fully understood” (Moore 79).
Although they possess some similar characteristics, PCBs are not pesticides. They are created synthetically and can assume different forms such as resins, liquids, and powders in certain applications. What has been particularly troublesome about PCBs is the resistant nature of these synthetically created compounds. These compounds, for example, have been found to be fantastically stable in several relevant respects; more specifically, PCBs are not flammable, reagents have had little affect on them, and “Destruction by burning requires a temperature of over 1300°C ” (Laws 321).
This stability and resistance, combined with threats to the environment and humans, has made PCBs a lingering public health and environmental concern despite their having being outlawed nearly four decades ago. Because of the stability and the highly resistant nature of PCBs it is hardly surprising that these synthetically created compounds were used widely and liberally before being outlawed. They were primarily, in the early years, used in industrial processes. “Prior to 1970, PCBs were used primarily in closed or semi-closed systems in electrical transformers, capacitors, heat transfer systems, and hydraulic fluids.
They were used to a minor extent in paints, adhesives, caulking compounds, plasticizers, inks, lubricants, car- copy paper, sealants, coatings, and dust control agents” (Laws 321). They were even used in surgical implants. Even a cursory examination of the uses to which PCBs were put demonstrates quite clearly that they were present everywhere; to be sure, sealants, coatings, inks, caulking compounds, and the like were present in homes, in schools, in factories big and small, and a threat to those environments and humans using or otherwise coming into contact with the PCBs.
The problem of environmental contamination was predicted and discovered early on; it was the pervasiveness of the contamination that both surprised and challenged those studying the effects of environmental contamination. The presence of PCBs in aquatic environments, whether oceans, riverbeds, or other waterways, is beyond dispute. But there is much more to the PCB problem than its presence in aquatic settings; the problem is that PCBs have operated as something quite akin to contagious contaminant. Fish and other aquatic organisms, for instance, have become contaminated by PCBs in their aquatic environments.
There have even been some studies that have argued that PCBs have entered our atmosphere through the process of evaporation. Fish, to take but one of many examples, are an important part of multiple food chains. The soil is contaminated and this is where food grows. PCBs are everywhere in many respects. We drink them, we eat them, we bathe in them, and we even breathe the. The precise danger posed to ecological systems, food chains, and humans remains the subject of much debate; however, the fact remains that PCBs have widely infected and contaminated virtually every part of our natural environment.
The threat to humans, from PCB contacts, varies; indeed, it has been stated that “With respect to human health, PCBs rank third in toxicity behind dioxins and furans when the most toxic isomer of each group is considered, but how dangerous PCBs in general are to human health is a bit unclear. ” (Laws 322). That lack of clarity noted, PCBs have nevertheless been linked to and associated with a number of human diseases. Some of the milder diseases have resulted in dermatological problems such as rashes and acne.
Other studies have suggested rather persuasively that damage to the human liver may result from PCB exposure that causes or otherwise induces changes in human blood and urine. Common symptoms mentioned in the literature include feelings of fatigue, coughing, nausea, dizziness, eye irritation, and open sores on the bottom. A more insidious type of threat to humans involves a mother’s breast-feeding, a child’s cognitive development, and whether sufficient PCB contact can enter the human food chain so as to damage a child’s cognitive capacity as well as trigger genetic alterations that will be passed on intergenerationally.
Ultimately, when considering the threat to humans from PCBs, researchers have been extraordinarily concerned with the degree of PCB contact or exposure that will trigger the onset of PCB poisoning symptoms or the aforementioned diseases. There has been some suggestion, for instance, that a mild exposure is not particularly dangerous or threatening. In the case of commercial fishing it has been noted that “for most persons the principal source of exposure is the consumption of contaminated fish; and until the mid-1970s, the concentrations of PCBs in the human diet were comparable to the levels that proved toxic to rhesus monkeys” (Laws 323).
It is significant that PCB concentrations are lower in oceans than in polluted waterways such as the Hudson River and the Great Lakes. The fact remains, despite some debate regarding contact or exposure thresholds, that PCBs are widespread and pose a threat to human health and welfare. A solution, or set of solutions, to the environmental contamination caused by PCBs remains somewhat elusive because of the extremely stable and highly resistant nature of the PCB compounds.
Generally speaking, academics and policymakers have sought to destroy or otherwise eliminate PCB contamination through (1) physical methods of destruction such as incineration, (2) microbial techniques designed to encourage PCB decomposition and (3) chemical approaches which have sought to eliminate or otherwise moderate the toxicity of contaminated sites. The physical methods have been inadequate given the resistance to heat and other physical stress points.
Similarly, the microbial approaches, particularly those seeking an effective means to decompose PCBs in soil or other places, is hindered by the non-biodegradeable nature of the PCB compounds. The most promising solution, in short, would appear to be a chemical approach that dealt with the minimization or elimination of toxicity levels. In the final analysis, though PCBs have been outlawed for many years, they remain a threat to the environment and to human beings. More troubling, their stable and highly resistant nature makes finding a viable clean-up solution a challenging endeavor.
For the moment, barring some technological breakthrough, chemical approaches to toxicity reduction appear to be the most promising. Works Cited “Polychlorinated Biphenyl. ” The Columbia Encyclopedia. 6th ed. 2007. Questia. 2 Apr. 2009 <http://www. questia. com/PM. qst? a=o&d=112880291>. Laws, Edward A. Aquatic Pollution: An Introductory Text. 3rd ed. New York: Wiley, 2000. Questia. 2 Apr. 2009 <http://www. questia. com/PM. qst? a=o&d=113404845>. Moore, Colleen F. Silent Scourge: Children, Pollution, and Why Scientists Disagree. New York: Oxford University Press, 2003. Questia. 2 Apr. 2009 <http://www. questia. com/PM. qst? a=o&d=103963654>.Sample Essay of PaperDon.com