At the time when GE was expanding operation along the Hudson, electric companies used organic coolants in electrical capacitors, but these compounds were not efficient in dispersing heat, causing the capacitors to explode. Many assumed this problem was solved in the 1920s with the development of polychlorinated biphenyls (PCBs) (Claudio 2002). In the beginning, PCBs seemed to have many virtues and no obvious faults. They are nonflammable and extremely stable, and early toxicity tests did not reveal any hazardous effects; these early signs made them an excellent choice for coolants in electrical capacitors. (Colborn, et al 1997). PCBs were widely used in many commercial products for 36 years before questions were raised as to their possible toxicity. In the coming decades, as scientists studied the human health effects of the chemical compound, companies such as GE were discarding PCBs in garbage dumps, where they leaked into the environment. Waste from GE’s Hudson Falls and Fort Edwards plants leaked directly into the Hudson River, thanks to the permit from New York State, and settled into the silt that backed up behind the Niagara Mohawk hydroelectric dam at the south end of Fort Edward. By 1973, the dam was considered a hazard and was demolished, sending the backed up PCBs cascading down the river (Tucker 2002).

In 1975, the first large study showing evidence of PCBs as carcinogens was published by Renate Kimbrough in the Journal of the National Cancer Institute. Kimbrough showed that rats fed varying doses of PCBs developed liver cancer on a “dose-response curve,” meaning that the more PCBs they were fed, the more they developed the cancer. This evidence was enough to convince the EPA to hold the National Conference of Polychlorinated Biphenyls, which led to the recommendation that PCBs be considered a human carcinogen. In 1976 the United States banned the manufacture of PCBs, but did not address existing PCBs, allowing their continued use in closed applications such as transistors and small appliances. It is estimated that during the time of their manufacture, 3.4 billion pounds of PCBs were produced worldwide (excluding the USSR). PCBs were loose in the environment, and when scientists began looking for them, they found them nearly everywhere – in air and soil, in the sediment of rivers, lakes and estuaries, in the ocean and in animals (Colborn, et al 1997).

Since the EPA decision to ban the manufacture of PCBs, there has been a great deal of debate over the possible human health effects of PCBs. GE has funded various studies, including one by Dr. Irving Selikoff of Mt. Sinai Hospital in New York, for which the company gave him access to its records since 1940. In 1982, Dr. Selikoff published his results, stating that he found no excess of cancer deaths or other serious side effects among 300 GE workers exposed to PCBs throughout a 30-year period. Similar results were found in a study conducted by the National Institute of Occupational Health and Safety concerning an electrical equipment manufacturing company (Tucker 2002). More recently, GE commissioned a study by Renate Kimbrough, the scientist who originally found that PCBs were hazardous to rats in 1975. The company asked her to expand on Dr. Selikoff’s study by investigating all 7,025 people ever employed at the Fort Edward and Hudson Falls plants. In 1999, she published her study in the Journal of Occupational and Environmental Medicine, contending that the workers had no increase in mortality compared with regional mortality rates. This study, along with other industry-funded science, has been criticized as potentially biased. Specific contentions with the Kimbrough study are that only one third of the study’s subjects had worked in capacitor manufacturing for more than five years, and that exposure assessment was not conducted on the subjects (Claudio 2002).

However inconclusive or dubious the science surrounding the carcinogenic effects of PCBs, there are many other hazardous health effects attributed the chemical compound, which have scientists worried. PCBs have been identified as hormone disruptors, which is exceedingly worrisome when one considers how ever-present they are in the environment. According to Colborn et al, “[PCBs] have spread throughout the planet and into the body fat of almost every living creature” (2002, 89). The very properties that made PCBs excellent coolants for industrial use also make them persist in the environment, resisting the break-down process that many harmful chemical compounds experience. In addition to persisting in the environment, PCBs biomagnify as they work their way up the food chain. According to Colborn et al, concentrations of PCBs in animal tissue can be magnified up to 25 million times from the original concentration (2002, 27). This statement does not bode well for those on the top of the food chain – humans. So, according to recent science, PCBs are everywhere in the environment, are especially potent high up on the food chain, and have been shown to disrupt the endocrine system (Colborn et al 1997; Claudio 2002). 

Research by the EPA’s Superfund Basic Research Program (SRBP) on PCB toxicity suggests that concentrating on cancer may have caused earlier researchers to miss the bigger picture. Exposure to PCBs during gestation and early development, due to the compound’s endocrine disrupting characteristics, causes many problems in growth and development. PCBs can be passed on through the placenta or through breast milk, and while scientists do not know all the answers as to how this affects our children, there is a general consensus that humans carry high enough levels of such chemicals to endanger their young. According to Colborn et al, during breast feeding, infants are exposed to five times the allowable daily level of PCBs set by international health standards for a 150-pound adult (1997, 107). The amount of chemical compounds we are passing on to our offspring could leave them with serious health problem, and while there is still debate over the exact effects of PCBs, the possible threat they pose is enough to convince many that they are an environmental problem that should be dealt with swiftly.