Office of Pollution Prevention and Toxics
U.S. Environmental Protection Agency
401 M Street SW
Washington, DC 20460
January 30, 1997
This document has been subjected to internal review at the U.S. Environmental Protection Agency (US EPA); however, the contents of this document do not necessarily reflect the views and policies of the EPA, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. This document is intended only as an informative summary document of the PCB experience in the United States.
This paper was developed by the U.S. Environmental Protection Agency (EPA) and provides an assessment of the management of polychlorinated biphenyls (PCBs) in the U.S. PCBs are among a group of persistent organic pollutants currently being assessed by the United Nations Environment Program (UNEP). It is hoped that this paper will support the UNEP effort by providing information on the U.S. experience with these substances.
Although PCBs are no longer produced commercially and represent a small part of the waste stream in the U.S., they persist in the environment for many years and can be found in air, water, soil, and food. Actual or potential health effects that are associated with PCBs include cancer, reproductive and development toxicity, impaired immune function, effects on the central nervous system, and liver changes. Properties such as low flammability and good insulating potential made PCBs valuable to manufacturers, and they were used extensively in a number of applications. Examples include electrical equipment, hydraulic and heat transfer systems, plasticizers, surface coatings, carbonless copy papers, and pattern waxes for investment castings. In 1979, most manufacturing, processing, distribution in commerce, and use of PCBs was banned in the United States by the 1976 Toxic Substances Control Act (TSCA).
The U.S. regulatory program and related policies cover these aspects, as well as PCB storage, spill response and cleanup, and disposal. Other key components of the PCB management program in the U.S. include requirements for waste tracking, recordkeeping and reporting, and imports/exports. The applicable regulations may vary depending on the concentration of PCBs in the material (i.e., stricter standards for higher PCB concentrations). Releases to the environment, including air, water, soil, and food, appear to have decreased over the years, indicating that the U.S. approach to managing PCBs is working .
The U.S. regulations establish standards for disposal (including treatment) of PCBs, or allow technologies of equivalent effectiveness. That is, the regulations allow the use of alternative technologies if it can be proven that these other technologies can perform as well as incineration and do not cause harm to health or the environment. Incineration, chemical waste landfills, and high-efficiency boilers are specifically authorized for PCB disposal in the U.S. regulations. Other technologies also have been approved for PCB treatment or site cleanup, including thermal desorption, chemical dechlorination, solvent extraction, decontamination, and soil washing. Additional technologies are currently being tested, including solidification/stabilization, vitrification, and bioremediation. It should be noted that some of these technologies may produce wastes that require additional treatment.
Oftentimes, it is not known whether PCBs are present in specific equipment or other products without testing. In such cases, the United States requires the use of certain assumptions regarding PCB concentrations in products (e.g., if a transformer displays no label or other information indicating the type of dielectric fluid, then the transformer must be assumed to contain 500 ppm or greater PCBs). Such items would be subject to PCB regulatory requirements for items containing PCBs at a particular concentration (e.g., greater than 500 ppm PCBs).
There is currently adequate storage and disposal capacity for PCBs in the United States (except for radioactive PCB wastes), with most facilities operating below storage or disposal capacity. At the present time, U.S. PCB regulations allow imports of PCBs in concentrations of 50 ppm or greater for disposal at approved facilities, but with the exception of PCB items at concentrations below 50 ppm they do not allow exports. Proposed changes to the PCB regulations, however, would allow exports if specified conditions were met. International agreements also may apply to PCB waste shipments. For example, the U.S. has hazardous waste agreements with Canada and Mexico that apply to PCBs.
For other countries considering the development of a PCB management program, several key factors will probably affect the type of program chosen, including:
The United Nations Environment Program (UNEP) and other international organizations are in the process of assessing persistent organic pollutants (POPs) and providing information on appropriate management of POPs. Thus far a number of POPs, including polychlorinated biphenyls (PCBs), have been identified as priorities. This document, which provides information about the United States' experience in managing PCBs, may be used along with information on other countries' experiences in managing the risks associated with POPs, to facilitate the implementation of an international agreement to reduce releases of these pollutants into the environment and to provide guidance to countries seeking to develop their own PCB management programs.
This paper was developed by the U.S. Environmental Protection Agency (EPA) and provides an assessment of the management of PCBs in the U.S. After a brief introduction to PCBs, the paper outlines ways to identify products containing PCBs, the sources of PCBs in the U.S., the efforts that the U.S. has made to control PCB emissions and releases, and the technologies currently available and used to control or manage PCBs. The paper concludes with a discussion of the U.S. experience and its potential applicability to countries that want to initiate or enhance PCB control programs.
The term polychlorinated biphenyls, or PCBs, refers to a group of 209 chlorinated isomers (congeners) of biphenyls . In the United States, PCBs were produced commercially for approximately 60 years and found application in a variety of products: as coolants, insulating materials, and lubricants in electrical equipment (such as transformers and capacitors), and, to a lesser extent, in applications such as hydraulic fluids, plasticizers, surface coatings, adhesives, pesticides, carbonless copy, dyes, and waxes . These products were used throughout the U.S. and were also exported to many other developed and developing countries. The properties of PCBs that made them valuable for industrial applications included extreme stability, chemical inertness, resistance to heat, and high electrical resistivity or high dielectric constant .
PCBs are virtually insoluble in water but are soluble in organic or hydrocarbon solvents, oils, and fats. This characteristic, combined with their persistence, means that they do not degrade easily in the environment and may bioaccumulate up the food chain. As evidence of their toxicity began to be reported in the early 1970s, the manufacturer of PCBs began withdrawing them from the market. Under the 1976 Toxic Substances Control Act, the U.S. banned the manufacturing, processing, and distribution in commerce of PCBs. The Act also bans most uses and regulates disposal of PCBs. Subsequent actions have resulted in a comprehensive regulatory system that closely controls labeling, waste tracking, decontamination, disposal, and destruction of PCBs, PCB-containing equipment, and PCB-contaminated media.
Laboratory animal studies of PCBs indicate that PCBs are oncogenic (tumor-causing). Studies of cancer in humans in occupational settings and following community exposures suggest that some mixtures containing PCBs are probably carcinogenic (cancer-causing) .
Data show that some PCBs have the ability to alter reproductive processes in mammals, sometimes even in doses that do not cause other signs of toxicity. Postnatal effects have been demonstrated in immature animals, following exposure to PCBs prenatally and via breast milk . Completed studies and studies underway in human populations suggest similar potential [5,6,7,8,9,10, 11,12].
In some cases, chloracne (severe dermal lesions) may occur in humans exposed to PCBs in occupational settings. Severe cases of chloracne are painful and disfiguring, and may be persistent . Other non-cancer, short-term effects of PCBs in humans include body weight loss, impaired immune function, and effects on the central nervous system, causing headaches, dizziness, depression, nervousness, and fatigue. Chronic exposure may also result in changes to the liver and related enzyme activity .
Products of incomplete combustion of PCBs include polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs), both of which may be more toxic than PCBs themselves and have been associated with embryotoxicity, teratogenicity, reproductive effects, and oncogenicity .
PCB exposure routes include: dermal exposure through direct contact (e.g., with contaminated soil); ingestion of food, soil (by children), or water contaminated with PCBs; and inhalation of PCB-contaminated particles in ambient air. PCBs are primarily stored in adipose (fatty) tissue and have been found in serum and human milk .
Certain PCB congeners are among the most stable chemicals known, and they decompose very slowly once released into the environment. PCBs are easily taken up and stored in the fatty tissue of freshwater and marine organisms, including fish, which then may be eaten by people. PCBs are toxic to fish at very low exposure levels and can adversely affect their survival rate and reproductive success. Chronic exposure of animals to PCBs can lead to disrupted hormone balances, reproductive failure, or carcinomas .
PCBs accumulate in aqueous sediments, and therefore may be consumed in significant quantities by bottom feeding marine species and by insect larvae. Predatory birds such as osprey and pelicans, which consume large quantities of potentially affected species, may themselves become significantly affected. PCBs have anti-estrogen properties that can inhibit calcium deposition during egg shell development, leading to insufficiently strong shells and premature loss. Anti-androgen effects of PCBs may lead to adverse effects on male reproductive capabilities of bird and animal species .
Data show that PCBs affect the productivity of phytoplankton and the composition of phytoplankton communities. Phytoplankton are the primary food source, directly or indirectly, of all sea organisms. Phytoplankton are also a major source of oxygen in the atmosphere. The transfer of PCBs up the food chain from phytoplankton to invertebrates, fish, and mammals can result in human exposure through consumption of PCB-containing food sources .
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