This is a modern tale about how everything is connected to everything
else in the environment. It begins in 1929 when the Monsanto
Corporation started selling PCBs (polychlorinated biphenyls). PCBs are
oily liquids that are very stable (they don't change their
characteristics) even when they get hot, and they don't conduct
electricity but they do conduct heat. Therefore, they make good
insulators in electrical transformers and capacitors. They have also
been used as hydraulic fluid, and in metal finishing. They are found in
electrical systems and other components of automobiles (which is one
reason junked cars and "car fluff" may be quite hazardous to your
health). For a time, carbonless carbon paper was made with PCBs.
Then scientists in the 1970s studying damage to wildlife from DDT
realized that there was something else causing the same problems as
DDT, and soon they identified PCBs as the culprit. It turns out that
PCBs interfere with birds' reproductive systems just the way DDT does--
they cause egg shells to become thin, so the eggs get crushed when the
mother sits on them, and they never hatch. Other evidence about hazards
from PCBs came to light and in 1976 Congress banned PCB production--the
only chemical Congress itself has ever banned.
Nevertheless, Monsanto had sold a lot of PCBs before Congress cut them
off at the knees; as a result, there are 1.2 million tons (2.4 billion
pounds) of PCBs loose somewhere in the world. Remember, they are very
stable compounds (that was the reason for their commercial success), so
they don't degrade or disappear easily.
Now a recent series of studies has begun to discuss the whereabouts of
all the world's PCBs. Sixty-five percent of them are still in use in
electrical equipment that will be getting old and ready for replacement
during the '90s, or are in landfills. Twenty percent have already
reached the oceans. Eleven percent are in terrestrial soils and
sediments; 4% have been incinerated or otherwise degraded.
Eighty-five percent of the world's PCBs are held within developed
countries, fifteen percent exist in developing countries.
PCBs have a broad range of unpleasant effects. They accumulate in fatty
tissues of living things (birds, fish, people, etc.) and they readily
pass through the walls of cells. Cells are the tiny bags of fluid of
which every living thing is built. For example, a typical human is
constructed of 50 trillion cells. Chemicals that can pass through the
walls of cells can cause all sorts of mischief, and PCBs are no
exception. PCBs can cause cancer and they can promote cancer (that is,
other chemicals when combined with PCBs develop the ability to cause
cancer). PCBs also cause birth defects in humans and animals. PCBs
damage the human immune system (and probably the immune systems of
other creatures as well). PCBs also cause hypertension (high blood
pressure) and they cause strokes in humans. Women who ate fish from the
Great lakes mildly polluted with PCBs (at or below legal limits) bore
children with small heads and who suffer from significant learning and
behavioral defects. (See RHWN #61.)
PCBs enter the ocean by two routes--by deposition from the atmosphere
(when it rains) and by drainage from rivers. Atmospheric deposition is
by far the largest source; 98% of the PCBs entering the ocean arrive as
air pollution, only 2% arrive via river water.
Because PCBs can become airborne when they are released into the
environment, they have spread everywhere on earth. Recent studies in
sparselypopulated areas of Canada (northern Saskatchewan, Ontario, and
New Brunswick) have revealed that rainfall now carries 17 parts per
trillion (ppt) of PCBs. As a matter of law, the Ontario government
allows only 1 ppt of PCBs to be discharged into the environment, but it
has been difficult to get a court injunction against rainfall.
Between 1969 and 1984 the levels of PCBs in arctic polar bears
quadrupled. At the current rate of increase, by the year 2005 (16 years
from now) the average polar bear will have 50 parts per million (ppm)
PCBs in their fatty tissue (adipose tissue) and then polar bears will
meet the EPA (U.S. Environmental Protection Agency) criteria for being
classified as a hazardous waste.
Some species of cetaceans (the whale family) already far exceed polar
bears in PCB concentrations. Killers whales from the deep ocean have
410 ppm PCBs in their blubber, and blue-white dolphins off the coast of
Europe have 833 ppm. Thus these creatures must definitely now be
classified as hazardous wastes by EPA criteria.
The upper layer of water in the oceans plays an important role in this
story. The upper 50 micrometers of water (called the microlayer)
concentrates pollutants from atmospheric deposition (rain), terrestrial
runoff (rivers) and sewage disposal. (The dot over the letter i in this
newsletter measures 400 micrometers in diameter, so 50 micrometers is
1/8 of the diameter of the dot over an i.) In the microlayer, the
uppermost surface of the ocean, pollutants are found at concentrations
10 to 100 times greater than the average concentration in ocean water.
Plankton are the tiny creatures that form the bottom-most level of all
ocean food chains. They carry out photosynthesis, using energy from
sunlight to convert carbon dioxide and water into plants, which are
then eaten by creatures that are eaten by other creatures, and so
forth. Plankton live in the microlayer because that's where there's
most sunlight for photosynthesis. Therefore they absorb the
concentrated pollutants. Then when they are eaten, they pass the
pollutants to the next creature, which passes them on to the next
creature and so on. Because PCBs are soluble in fat, they are retained
in the bodies of fish and mammals and at each step in the food chain,
the concentration of PCBs increases. Animals at the top of an oceanic
food chain (like whales) will have a concentration of PCBs in their
bodies 10 million times greater than the concentration in plankton at
the bottom of the chain. (This is called biomagnification or
bioconcentration, and it is the reason why dilution is no solution to
The next-to-last chapter in our unfolding story is that marine mammals
(seals, porpoises, whales, etc.) have a genetic predisposition to
reproductive failure caused by PCBs. This is simply bad luck. PCBs
happen to act like hormones in marine mammals, interfering with their
ability to reproduce.
Joseph Cummins, Associate Professor of Genetics at University of
Western Ontario, writing in the journal, THE ECOLOGIST, says that if
even as little as 15% more of the world's stock of PCBs gets into the
oceans, "the extinction of marine mammals would be inevitable." He
says, "The consequence of failing to control PCB releases to the oceans
will be the extinction of marine mammals and the chemical fouling of
the ocean fisheries, rendering them unsuitable for use by humans." Dr.
Cummins believes that the "developed" world can manage its PCB stocks
sensibly. (We note that he does not offer a basis for this belief.)
However, he is concerned that the developing world hasn't the financial
resources to control the PCBs now in use in its domain. He therefore
suggests that Monsanto should purchase back all its PCBs from wherever
they are located in the developing world, to avoid PCB-induced calamity
for all the world's oceans in the coming decades.
For its part, Monsanto makes no apology for its behavior. It continues
to operate very profitably, introducing new chemicals into use at every
opportunity. And that concludes our modern tale.
Get: Joseph Cummins, "Extinction: The PCB Threat to Marine Mammals,"
THE ECOLOGIST Vol. 18 (1988), pgs. 193-195. And while you're thinking
about it, why not send a note of thanks to our friends at Monsanto who
have done so much to make the modern world the kind of place it is
today: 800 North Lindbergh Boulevard, St. Louis, MO 63141-7843. Or
phone them at (314) 6941000.
Descriptor terms: oceans; pcbs; water pollution; air pollution;
wildlife; fish; marine mammals; biomagnification; extinction; species
loss; developing countries; monsanto; global environmental problems;