|BACKGROUND ON HUDSON RIVER CONTROVERSY
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).
The Science Behind PCBs
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).
What We Know for Sure
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.
photo by Elizabeth Adams
Above is a rendering of the process of
biomagnification through the food chain in Lake Ontario. The higher up
on the food chain, the more concentrated PCBs become. Figure from Our Stolen Future (Colborn et al, 27).