Sample Research Paper: Polychlorinated Biphenyls (PCB) Impact on Human & Animal Habitat
This 2,700-word example of our scientific research paper writing expertise contains APA style citations, a table, a PCBs diagram in image format, lists, and a multi-format annotated bibliography of PCB references (i.e., each entry includes informative, critical/evaluative, indicative, and summary data).
As a result of increased industrial emissions, many human habitats in the United States and abroad have been contaminated by various types of pollution over the years, including one particularly noxious substance, polychlorinated biphenyls. Polychlorinated biphenyls, more commonly known by their acronym PCBs, have been shown to cause damage to the liver and kidneys, and this chemical represents a profound threat to the health of humans, especially younger ones, who live in regions where it becomes concentrated in the ecosystem and may even end up in human breast milk. Despite a number of environmental initiatives designed to reduce these emissions and the impact of PCBs on humans, there has been a paucity of success in remediating this harmful chemical and policymakers continue to search for better approaches to mediating the impact of the industrial and municipal discharges into regions where humans can be adversely affected by PCBs. By any measure, polychlorinated biphenyls continue to pose a continuing threat to human health and environmental integrity today. To gain some further insights into the source of this chemical pollutant and what steps have been taken in an effort to address the problem, this research paper provides a review of the relevant peer-reviewed and scholarly literature concerning PCBs, followed by a summary of the research and important findings in the conclusion.
Research Paper Review and Discussion of PCBs
Much has been accomplished in recent years to clean up the environment in the United States. For example, the Clean Water Act (officially termed the "Federal Water Pollution Control Act") was enacted in 1972 with a broad mandate: "To restore and maintain the chemical, physical and biological integrity of the nation's waters"; however, the immediate goal of the Act was to stop municipalities and industries from dumping untreated or poorly treated wastes into public waters (Mcgivney & Speart, 1993, p. 29). Some of this poorly treated effluence contains polychlorinated biphenyls (PCB) which is described by the Environment Protection Agency (EPA) as "a very toxic chemical compound that poses danger to people and the environment" (quoted in de Vera, 2008 at p. 3).
This controlling legislation was enacted in large part to help address emissions of toxic substances such as PCBs which were becoming virtually ubiquitous by the 1970s due to the increasing industrial uses. In this regard, Schweitzer (1991) reports that, "In the early 1970s PCBs were showing up everywhere—in fish from the Great Lakes, in streams and estuaries, and in soil samples from around the country" (p. 10). According to Mcgivney and Speart, though, the Clean Water Act does not stipulate a standardized approach to testing for and treating areas that have been contaminated by PCBs, resulting in a wide range of remediation approaches being in place across the country. For instance, these authors note that, "The Clean Water Act requires states to designate uses for rivers--usually fishing and/or swimming--and then report to the EPA on whether or not those uses are met. The EPA offers guidelines, but the decision on which rivers to monitor and what testing methods to use is up to the states" (Mcgivney & Speart, 1993, p. 30).
Like a number of other toxic substances used in industrial applications, PCBs have their valuable uses, many of which brought them into contact with humans and animals over the years. In this regard, Moore notes that, "Because PCBs have some desirable electrical properties and are chemically stable and resistant to exploding when heated, they quickly came into wide use in electrical transformers, for lubrication, and in many other products. For a short time PCBs were even used in paints used as sealers inside farm silos" (p. 79).
Further, as with many other noxious substances found in industrial effluence, PCBs continue to have valuable applications in a wide range of settings. In this regard, de Vera reports, "PCB is thin, light-colored liquid to yellow or black waxy solid used as heat exchange fluids in electric transformers or capacitors, and as plasticizers in paints, plastics, and rubber products, and as additives in dyes, pigments, sealants, and carbonless copy paper" (p. 3). Likewise, Moore (2003) reports that, "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" (p. 79). According to a study by Fiedler (1999), some of the chemical and physical properties possessed by PCBs have made them particularly useful for a wide range of applications in the past (see Table 1 below for a description of these applications); some of the more important characteristics of PCBs that have contributed to their industrial uses include the following:
- Liquid at room temperature; density: 1.182-1.566 kg/L;
- Low water solubility; readily soluble in organic solvents;
- High flash point: 170-380°C;
- Low electric conductivity;
- Very high thermal conductivity;
- Extremely high thermal and chemical resistance (very high stability) (Fiedler, 1999, p. 62).
In spite of its manufacture being outlawed four decades ago, PCBs continue to raise their ugly head in ways that confound efforts to control these toxicants in the environment. For instance, according to May (2000), "Polychlorinated biphenyls (PCBs) are a family of about 200 industrial chemicals used as lubricants and coatings. Although PCBs were banned in the United States in the 1970s, these persistent compounds remain scattered throughout the environment. Like mercury, PCBs can contaminate fish, but PCBs also end up in many other foods, including beef, dairy products, pork, and human breast milk" (p. 37). Because humans are at the top of the food chain, these concentrations can be reasonably expected to continue to adversely impact humans in regions where accumulations of PCBs continue to occur, particularly in view of the exceptions to the controlling legislation that have been enacted and the fact that PCBs continue to be produced as an unintentional byproduct of other industrial processes.
Some of the more common and valuable applications of PCBs that have emerged over the years are described further in Table 1 below.
Table 1: Common Industrial Applications for PCBs
Source: PCBs - Polchlorinated bipenyls - facts, regulations, guidance, 2009; Moore, 2003; Fiedler, 1999.
In spite of a growing body of research devoted to better understanding the operation of PCBs when they enter the ecosystem – and subsequently animals and humans – these processes remain better described that understood. As Moore emphasizes, "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" (p. 79). Nevertheless, a growing body of research confirms the toxicity of these compounds on animals and humans and there are efforts underway across the country and around the world to help address these issues in a comprehensive fashion.
While the EPA has been successful in assisting a number of states and local communities in improving the quality of their waterways by eliminating such untreated discharges of PCBs and other toxic substances, many regions around the country have been so adversely affected by accumulated industrial and municipal discharges that these areas resist the usual cleanup processes available and these regions are going to require some innovative techniques if they are going to be resolved without further endangering people living in these areas. According to one authority, "Most of the dangerous pollutants that are discharged into rivers are usually sequestered in sediment in river bottoms. Contaminants such as mercury, zinc, chromium, cadmium, and lead may remain in the sediment for years, slowly leaking low doses of pollution into the water" (Good news, 2002, p. 7). In the final analysis, it may well be that one of the most important outcomes of the Clean Water Act's efforts to clean up the nation's waterways date has been to reduce or eliminate untreated discharges into these waterways which provide the opportunity for natural processes to remediate the contaminants, but some areas remain so highly concentrated they resist even these natural processes.
This has been the case with several waterways around the country, including a 40-mile stretch of the Hudson River from the river's mouth to New York's Tappan Zee Bridge where natural processes have facilitated the dispersion process in ways that resemble a washing machine. In this regard, the editors of The Futurist report, "A mixture of salt and fresh water, tidal forces, storms, rain, and spring runoff have created a dynamic 'rinse cycle' that repeatedly draws polluted sediment up from the river bottom, churns it, and then returns it to the bottom" (p. 7). These natural processes, though, do not necessarily remove these contaminants from the environment altogether, but rather diminish their immediate potential harmful effects or sends them packing to the ocean depths to the extent that they do not pose any further immediate threats to human occupants of these regions. In this regard, Moore (2003) reports, "PCBs are a highly contentious topic in the United States because of conflicts over how to clean up the Hudson River in New York, as well as other PCB hot spots around the country. Just as with mercury, two pollution disasters called attention to the effects of PCBs and related chemicals on children's development" (p. 78).
In response to these reports, a growing number of environmental groups across the country and around the world have called for a ban on these toxic substances because there are alternatives available for their current use in industrial settings (Rostow, 1978). This has been the case in the United States where the Toxic Substances Control Act (TSCA), enacted in 1976, now prohibits the manufacture of PCBs, mandates the phasing out of their current uses, and stipulates procedures to be used for their disposal (PCBs - Polchlorinated bipenyls - facts, regulations, guidance, 2009). According to these authors, "PCBs are the only chemical class specifically named in TSCA because Congress believed that the chemical and toxicological properties of PCBs posed a significant risk to public health and the environment" (PCBs - Polchlorinated bipenyls, p. 4).
Among the key provisions of the TCSA controlling legislation and various EPA policies are the following:
- Assumption of PCBs if not labeled, location and content of PCB labels;
- Visual inspection and recordkeeping for PCBs in use or stored for reuse;
- Other record-keeping requirements;
- Disposal restrictions on use and burning of used oil containing PCBs;
- Storage for disposal;
- Spill prevention;
- PCB spill cleanup policy;
- Food and feed restrictions;
- PCB transformer fire regulations;
- Substitute dielectric fluid;
- Storage container specifications;
- Notification and manifesting rule;
- EPA policy on physical separation of PCBs;
- Reclassification of transformers;
- PCB fluorescent light ballast disposal; and,
- PCBs uses in laboratories (PCBs - Polchlorinated bipenyls, p. 5).
There have been some amendments to the TSCA since its enactment that specifically relate to PCB and its disposal. For example, May reports that, "In 1998, the EPA amended the Toxic Substances Control Act to streamline procedures for disposing of PCB wastes. The change was intended to protect human health and the environment against unreasonable risks from PCBs by providing cost-effective and environmentally protective disposal options that will reduce exposure to PCBs by encouraging their removal from the environment" (p. 37). Furthermore, the 1998 amendment also provided for some specific continued uses of PCBs and other materials that had been contaminated with PCBs in those cases where exposures was thought to be controllable and in other cases where removal and disposal of the material represented a cost-prohibitive mandate or would otherwise be regarded as impractical (May, 2000). These fundamental changes to the law mean that PCBs continue to represent a very real threat to humans and animals that live in regions of the country where accumulations tend to occur, including in particular the nation's waterways. Furthermore, although these compounds are no longer manufactured and commercially used in the United States, they continue to be produced as a byproduct of existing manufacturing techniques (PCBs - Polchlorinated bipenyls). The environmental threat represented by these substances has also attracted the attention of the international community. For example, de Vera (2008) reports that the international community has also singled out PCBs for phasing out from their current industrial applications. As de Vera points out, "Environment advocates recently expressed their support for the elimination of polychlorinated biphenyl largely used in paints, plastics, and rubber products, which is the probable cause of human carcinogen" (p. 3).
Moreover, based on a number of recent longitudinal clinical studies that clearly point to the toxic nature of PCB (Moore, 2003), the international community reached a consensus on this substance in 2001 by agreeing to restrict and eventually eliminate PCBs under the Stockholm Convention on Persistent Organic Pollutants (POPs) (de Vera). According to Wigle (2003), the Stockholm Convention mandates that the United States, the European countries, and several other countries abide by the following stipulations:
- Regulate 16 persistent organochlorine compounds (a group to which PCBs belong);
- Ban production and limit uses of PCBs;
- Require the use of the best available technology to limit air emissions from major stationary sources of toxicants;
- Reduce total national air emissions below the levels for a benchmark year; and,
- Manage stockpiles of waste persistent organochlorine pollutants in an environmentally sound fashion (p. 155).
Notwithstanding these strict guidelines, exceptions continue to be made for certain uses of PCBs and the chemical continues to work its way into the ecosystem in ways that confound efforts to address the problem today.
PCB Research Paper Conclusion
When something such as toxic waste disposal is made a priority, it is by definition supposed to get better. However, the data obtained for this PCB research paper is absolutely consistent in demonstrating that the serious problems represented by heavy concentrations of PCBs in the nation's waterways, in general -- and the Hudson River, in particular -- have made remediation difficult and expensive. Unfortunately, some of the treatment approaches may prove even more harmful than simply leaving the PCB concentrations in place, which further complicates the problem. In addition, changes to the controlling legislation in recent years have allowed for the continued use of PCBs in certain circumstances and the compound continues to work its way into the ecosystem in insidious ways. Despite the glaring need for more research to identify better ways of remediating the affected parts of contaminated waterways across the country, the harsh reality of the situation today is that the industries that are primarily responsible for the problem in the first place continue to delay the remediation process by citing studies they have sponsored in an attempt to avoid responsibility for the cleanup that is so desperately required. Although this may seem to be just sound business practice, the enterprises involved in the emissions are also primary stakeholders in helping to ensure that a sustainable environment is maintained and that their clientele remain sufficiently healthy to use their products and services in the future. In this environment, incinerating the PCB-laden sediments appears to represent the best approach currently available because it would dispose of these toxic materials once and for all in spite of the higher costs associated with this remediation technique. Finally, because PCBs continue to be allowed for use in certain circumstances and are also released into the environment as a byproduct of other industrial processes, the best approach to reducing these emissions might be to identify a commercial use for them in ways that alter their chemical structure to eliminate their toxicity while retaining their fundamental usefulness to humans.
Research Paper References (Annotated Bibliography)
Author cites the historic sources of industrial pollution into the Hudson River and emphasizes that among the toxicants released into this waterway, PCBs are among the most dangerous for humans and animals alike. By the time the Toxic Substances Control Act was passed in 1977, companies such as General Electric had already released enormous quantities of PCBs into the Hudson and a significant percentage of these releases remain intact today. Author also reports that scientists remain divided concerning how best to remediate this substance and notes that some techniques may cause more harm than simply leaving the PCB concentrations alone. This was a particularly valuable study for the purposes of this investigation.
Author cites the toxicity of PCBs and reports on recent efforts by the international community to eliminate and/or reduce its use in the U.S., Europe and other countries. Author includes a description of the Stockholm Convention on Persistent Organic Pollutants (POPs) enacted in 2001 as a demonstration of the commitment of the international community to address this problem, but emphasizes the need for more stringent regulatory oversight in the future. This was a useful report for this study given its recent publication date and the overview provided concerning efforts abroad to address the problem.
This online resource provided a comprehensive overview of PCBs, their historic industrial applications, a description of key controlling legislation and the adverse health effects that have been found to be related to exposure to PCBs. This is an excellent resource that contributed to this study in several ways, including common industrial applications that continue to be used based on the compound's valuable inherent chemical properties.
Author presents a comprehensive overview of the chemical structure of PCBs, their common historical industrial applications in the United States and Germany, commercial brands, and recent trends in their use in the U.S. and abroad. Author also provides a useful description of PCB's molecular structure and include several graphs and tables to illustrate his points. This was also determined to be valuable addition to the instant study.
Notwithstanding the other bad news concerning the toxicity of PCBs and their lingering effects on health of humans and animals in regions where the compound accumulates, this report emphasizes that some progress has been made in remediating PCBs in general and in the Hudson River in particular. The study was deemed a valuable contribution to the findings of this study.
Authors provide a useful overview of recent clinical studies that have confirmed the health risk associated with exposure to PCBs, as well as various other toxicants that continue to find their way into the ecosystem. The segment on PCBs was sufficiently comprehensive to make this study a valuable contribution to the instant investigation.
Like the "Good News" report described above, authors also present some good news concerning remediation efforts of PCB concentration in the nation's waterways and other regions where accumulations of PCBs have adversely affected the health of humans and animals. Authors also provide a useful overview of the various laws that have been passed in recent years in an effort to reduce and/or eliminate the use of PCBs in the U.S., which was determined to be highly valuable for the purposes of this study.
Author reviews some of the recent studies and scientific evidence concerning how pollution adversely affects the quality of young people in particular and describes why the scientific community frequently disagrees concerning these findings. Author also provides a fact-filled description of the historic uses of PCBs and what steps have been taken to reverse this trend in recent years. Author's description of common industrial applications was determined to be especially useful for the purposes of this study.
The text was consulted only to determine a general time period in which viable alternatives to industrial applications for PCBs were first identified.
Published during a critical period in the nation's environmental debate, author provides a thorough discussion of how and why industrial pollutants have been used in the past and continue to be used. Author emphasizes that unless more drastic approaches to reducing the emission of pollutants into the ecosystem are taken today, future generations will inherit a legacy of environmental pollution that will undoubtedly be even more difficult to resolve than it is at present. Author's discussion of the historic uses of PCBs was deemed highly useful for the purposes of this study.
Author provides an analysis of how environmental factors and pollutants can contribute or detract from the healthful development of young people, and provides some useful information concerning controlling legislation affecting the use of PCBs. In sum, this is a valuable addition to any study of toxicants in the environment in general and PCBs in particular.