Synthetic organic chemicals:
A short history, Part 2
While many chemicals are derived from petroleum, another
major branch of modern materials science revolves around
another raw material. Around 1900, Herbert Dow, the
founder of Dow Chemical, split common salt to make
commercially valuable sodium hydroxide. In the process an
unwanted byproduct was released, a highly toxic green gas
called chlorine. Mr. Dow, a chemistry teacher, soon began
experimenting with this gas and combining it with other
elements, thus creating “chlorine chemistry.” This new
chemistry gave rise to solvents, pesticides and many other
useful but toxic chlorinated compounds. A prime
characteristic of chlorinated chemicals is the strength of
the bond created between chlorine and other atoms.
While this bond makes chlorine a valuable element for
chemists building new substances, it is also one of the keys
to understanding why chlorine is so dangerous. Once bonded
with another atom, the molecular toughness of chlorinated
compounds means they last a long time in the environment
and are very difficult to break down.
Today, there are about 15,000 chlorinated chemicals in
commercial use. Only very few have ever been completely
banned, but these few are some of the most notorious
substances ever invented. For example, the chlorinated
hydrocarbons polychlorinated biphenyls (PCBs) were once
used in electrical transformers in place of petroleum oils,
which often burned. But scientists in the late 1960s
discovered that the chemical was extremely persistent in the
environment and, worse, was accumulating in human beings
and responsible for very serious health effects that included
cancer and birth defects. Production of PCBs was halted soon
thereafter. In 1939, the now banned chlorinated hydrocarbon,
DDT, was introduced as an insecticide and miracle malaria
preventative. When Rachel Carson wrote Silent Spring, she
accurately predicted the environmental devastation that DDT
in particular, and the chlorinated hydrocarbons in general,
would bring. In the 1970s, chlorinated hydrocarbons would
be identified as suspected carcinogens and implicated in the
environmental devastation that turned now infamous
communities like Love Canal and Times Beach into
hazardous waste sites.
In more recent times, a growing body of evidence has emerged
to suggest that chlorinated compounds are responsible for an
ever expanding number of human ailments, including growing
numbers of different cancers, reproductive and developmental
disorders, and the disruption of the endocrine, or hormonal,
system in human beings. (For more information, read Our
Stolen Future, listed in Further Suggested Reading.)
More chemicals than
we know what to do with
Approximately 85,000 chemicals are in use today. According
to the Breast Cancer Fund, complete toxicological screening
data is available for only 7% of these chemicals, and more
than 90% have never been tested for their effects on human
health. In 1995, the National Toxicology Program concluded
that based on the tests they had conducted, something like
5% to 10% of all chemicals in production could be expected
to be carcinogenic in humans. That translates into 4,250 to
8,500 different chemicals, almost all of which have yet to be
regulated yet alone even identified by the government.
One of the best ways that citizens can protect themselves and
their communities from dangerous chemicals is by studying
the Toxic Release Inventory (TRI), the key to the Emergency
Planning and Community Right-to-Know Act (EPCRKA),
passed by Congress in 1986. Unfortunately, the TRI only
tracks 667 chemicals (including 30 chemical categories),
which make up less than 1% of all chemicals in production
and use. Still, many highly toxic compounds are reported in
the TRI, and looking at the annual TRI report (available at
http://www.epa.gov/tri/) is the best available way to find out
which are present in your community.
What makes an ingredient undesirable?
Now that we have some history under our belts, it’s time to
look at the ways in which the chemicals we’ve been discussing
affect the environment and human health. There are several
criteria that are used to evaluate ingredients in specific
products, and thus the environmental safety of the products
themselves. Any analysis of product ingredients should look
at their potential effects in these areas:
1) Air quality/atmospheric impact
The manufacture, use and disposal (especially through
incineration) of many common consumer products cause the
release of a variety of hazardous chemicals and compounds
into the air and atmosphere. These releases may include
direct introduction to the air via intentional use and indirect
introduction of toxic materials and harmful byproducts during
the manufacturing process. Evaluations of products and
ingredients should examine their potential contributions to:
• Global atmospheric ozone loss
• Acid rain
• Global warming
• Air pollution
2) Water impact
Use of specific products can directly and indirectly affect
ground water, aquifers and bodies of water, from streams and
ponds to oceans. This in turn affects all life, from insects and
fish to humans. Contamination can occur during consumer
use, manufacturing, or when a given product is emptied into
a public or private sewage system after use. Evaluations of
products and ingredients should examine their potential
contributions to:
• Water pollution
• Eutrophication
Eutrophication is a naturally occurring process by which lakes,
small streams and wetlands become dry, fertile land for forest
growth and animal habitat. Normally, this process takes
thousands of years and is part of a sustainable cycle.
Eutrophication occurs when excessive plant growth, including
the growth of algae, takes place in a given body of water.
When the plants and algae die, they settle to the bottom of
a lake, slowly filling it and becoming a food source that allows
other microorganisms to flourish. As these other
microorganisms thrive, they need oxygen to digest this food.
As they consume and remove oxygen from the waters, less is
left for the fish and other life forms living there, most of which
then die en masse. These fish kills can be caused by either
natural or man-made events. From the perspective of
household products, eutrophication is a concern when those
products contain ingredients, like phosphates, that promote
the rapid and unnatural plant growth that starts the
eutrophication process.
3) Land impact
Consumer products and specific ingredients can also
contribute to land-based environmental concerns. These
impacts can be caused by raw material and resource
extraction, and by manufacture, use and disposal of a given
product. Evaluations of products and ingredients should
examine their potential contributions to:
• Resource depletion
• Deforestation
• Loss of habitat and biodiversity
• Soil contamination
• Landfill space consumption
4) Human health
Common consumer chemicals and products can dramatically
impact human health at any stage in their life cycle, from
manufacture to use and disposal. Of particular concern is the
effect any ingredient or product has on the user and any effect
on the general population caused by accumulation in either
household or external environments. Evaluations of products
and ingredients should examine their potential to cause:
• Acute toxicity
• Chronic toxicity
Acute toxicity is any immediate health hazard caused by
contact with a product or chemical ingredient. Symptoms
of acute toxicity can range from simple internal or external
irritation to intestinal distress, convulsions and even death.
Chronic toxicity is any long-term, cumulative negative health
effect caused by repeated low-level exposure to either a
product or a specific chemical component found in either
the household or the general environment. The symptoms of
chronic toxicity appear over time and can include asthma,
allergies, cancer, endocrine, immune, and nervous system
damage; reproductive and developmental disorders; organ
damage; and the general condition commonly known as
multiple chemical sensitivity (MCS), also known as
environmental illness, a condition many scientists believe
is a severe body-wide allergic reaction to repeated contact
with toxic chemicals.
When considering how product ingredients impact the above
areas of environmental and health concerns, it’s necessary
to better understand an important factor that can have
a dramatic effect on their potential to cause damage:
biodegradability.
Biodegradability
Biodegradability in household chemical products is desirable
for two reasons. First, biodegradability means that the product
can be recycled by nature, or broken down into its smallest
parts via the action of microorganisms. For example, a piece of
paper, made from trees, will biodegrade into carbon dioxide
and water. The carbon dioxide and water can then be used by
other plants and trees. In a closed system, like a spaceship
or planet Earth, this type of recycling is necessary for the
system to be self-sustaining.
Biodegradability also means that the product will not be able
to stick around and accumulate in the environment.
When a chemical does not biodegrade, its concentrations
in the environment continue to increase as more and more
of the chemical gets added to existing amounts that are
themselves not biodegrading. Since toxic effects increase
with concentration, an otherwise relatively benign
chemical can quickly become a dangerous one if it does not
biodegrade and instead continues to “pile up” to unhealthy
levels in either the environment or the human body.
These growing concentrations of a chemical caused by a lack
of biodegradability are referred to as bioaccumulation. A good
example of the effects of bioaccumulation can be found in the
pesticide DDT. Like many chlorinated compounds, DDT does
not readily biodegrade and instead bioaccumulates. Though
small amounts of DDT were initially fairly well tolerated by
people and the environment, as more and more of this
chemical was used, more and more of it bioaccumulated in
the environment and in the fatty tissues of animals. In this
way, DDT began to travel up the food chain. Shrimp in
certain waters, for example, might have a little bit of DDT
in their tissues. When these shrimp are eaten by a small fish,
that fish adds the shrimps’ collective DDT stores to its own.
Over a lifetime of eating, that small fish can accumulate quite
a bit of DDT, little of which breaks down. When the little fish
and many others like it are eaten by a still larger fish, the
larger fish accumulates even greater amounts of DDT. When
that larger fish is caught and eaten by a person, all of the
DDT consumed by all of the various animals along the way
ends up in that person’s tissues. Human beings thus receive
the bioaccumulated DDT from the entire food chain because
we sit atop it.
One idea that is necessary to understand when talking
about biodegradation is the importance of the rate of
biodegradation. The speed at which a given material breaks
down makes a big difference in the bioaccumulation threat
it might represent. For example, a chemical that takes just
five days to decay is far less worrisome than a chemical that
takes five, 50 or 500 years to biodegrade. The
bioaccumulation of chlorinated chemicals in mammals,
including humans, is now suspected of disrupting sexual
development, reproduction, and may other essential
bodily functions through a process called endocrine
or hormone mimicking.
Many chlorinated chemicals, it turns out, have molecular
shapes that are almost identical to specific hormones. In the
hormone mimicking process, this similar shape allows these
chemicals to slip inside cells in place of legitimate hormones
and trigger cellular activity. Telling cells to perform certain
functions or behave in certain ways is a hormone’s main job,
and the body has thousands of kinds of these messengers. But
chemicals masquerading as hormones in the body often cause
cells to do the wrong things at the wrong times or in the
wrong amounts. The result is abnormal cellular behavior
and illness.
If these chlorinated chemicals and others like them were
biodegradable, they wouldn’t present such a threat. They’d
be constantly breaking down into harmless parts and would
therefore be relatively few and far between in the
environment. But, because they don’t break down, they
threaten to overwhelm the environment and the organisms
living there.
The natural balance of planet Earth
A final point to remember: we don’t live in isolation.
Everything we do affects the world around us. Breathing
consumes oxygen and releases carbon dioxide. We consume
food and release heat and waste. But having an impact isn’t
necessarily bad. On a simplified scale, our heat and wastes are
necessary for other organisms. Their heat and wastes, in turn,
combine with our own and are ultimately absorbed by plants,
which then become our food or industrial raw materials.
That’s the way it should be. The world we inhabit is a
beautifully balanced system of profound and complex
interactions among all its organisms. The impact each
organism has is necessary for this planetary system to work.
Unfortunately, humankind has developed lifestyles and
industrial processes that disrupt this self-sustaining balance.
Our objective now must be to minimize our disruptive
lifestyles and replace those industrial processes that threaten
the sustainability of nature’s cycles with processes that do not.
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