Polychlorinated Biphenyls (PCBs)

Polychlorinated biphenyls (PCBs) are a class of odorless, liquid, synthetic organic chemicals containing chlorine, hydrogen, and carbon that persist in the environment following use. PCBs have many applications, including dielectric fluid in electrical capacitors and transformers, hydraulic [Page 2226]fluids and lubricants, flame retardants, plasticizers, and carbonless copy paper. PCBs have been manufactured and used worldwide since their introduction in 1927, with Monsanto controlling the U.S. market since 1935 and accounting for half the global production.

PCBs have been widely used for more than 75 years, with about 1.65 million tons of cumulative production worldwide. These chemicals have several advantages: fire resistance, low electrical conductivity, high resistance to thermal breakdown, and high chemical stability. Unfortunately, due to their persistence, bioaccumulation, and biomagnification, they can cause several adverse health effects as they collect in fatty tissues in humans and other exposed animals in both terrestrial and aquatic systems. These include liver and immune system disorders, irritation of the skin and eyes, reproductive and developmental effects, and probably several types of cancer.

The United States banned the manufacturing, processing, distribution, and use of PCBs with the passage of the Toxic Substance Control Act in 1976. Internationally, PCBs are one of nine chemicals slated for elimination by the 2001 Stockholm Convention on Persistent Organic Pollutants, which took effect in May 2004 and will be fully implemented by 2025. Despite these efforts, large volumes of PCBs still exist in the environment. Disposal options include incineration, ultrasound, irradiation, chemical and thermal treatment, and special landfills for PCB-contaminated sediments and articles.

PCBs have been implicated in several major incidents of environmental contamination. Probably the first major case was in 1968 in Kyushu, Japan, where nearly 1,800 residents fell ill after eating Kanemi rice bran oil (yusho) contaminated with PCBs. Subsequently, more than 50 people died. A similar incident occurred in Taiwan in 1979. In several areas of the United States, thousands of chickens and hogs had to be slaughtered because they ate PCB-tainted feed. General Electric (GE), a large user of PCBs, dumped 1.3 million pounds of the chemicals into the Hudson River, New York, from 1947 until 1977. An early case of environmental justice involved the creation, in 1982, of a landfill for PCB-contaminated soil in rural Warren County, North Carolina, a predominantly poor African American community. Following years of PCB dumping by paper mills into the Fox River and Green Bay, Wisconsin, a natural resource damage assessment was conducted, leading to a settlement in 2004 of $60 million in compensation and restoration costs. Additional PCB dumping, causing concern over fish and shellfish contamination, has been widespread in the Great Lakes region. High levels of PCBs have even shown up in native peoples and wildlife in Northern Canada and Alaska due to long-distance transport. Most recently, nine pig farms in Ireland had used PCB-contaminated feed, resulting in the withdrawal and disposal of pork-containing products purchased in Ireland between September and December 2008.