United States
Environmental Protection
.Agency
Region V
EPA-905/9-79-007
November, 1979
Understanding
Toxic
Substances
NIMMlSAHSEi
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What are toxic substances?
Toxic substances are chemical
substances that may present an
unreasonable risk of injury to health or to
the environment. Many chemicals are part of
our daily lives, and a small percentage
of these are toxic. Toxic substances that
might be used around the home include
paint thinner, garden pesticides, drain-
cleaning chemicals, and some medicines.
Although such substances may be
beneficial when used correctly, they may
well be toxic if someone misuses them or
is exposed to excessive doses. Other toxic
substances are less familiar to the public
but are essential ingredients in the
manufacture of familiar products. Many
manufacturing industries produce toxic
waste products that must be disposed of in
an environmentally safe way. Although
most of us do not see the toxic wastes
produced in the manufacture of batteries,
paint, synthetic fabrics, and electrical
transformers, we contribute to the
production of these wastes whenever we
buy or use these products.
Why are toxic substances a problem?
Toxic substances are not always a
problem. Most people do not experience
problems with toxic products kept in the
home if they use and store these products
carefully. Problems with toxicants in the
home generally result from careless use or
storage of such products or from a lack of
information about their potential dangers.
Similarly, most problems with toxic
substances in the environment result from
careless or uninformed use and disposal
practices.
Chemicals are sometimes not
recognized as toxic until after they have
been used for many years and released
into the environment in significant
quantities. Polychlorinated biphenyls
(PCBs) are one example of such a chemical
group. PCBs were discovered in the late
1800s but were not used industrially in
this country until 1929. Fromi1929 to
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1971, PCBs were widely used in industry
because of their properties of chemical and
thermal stability, fire resistance, and non-
conductivity. They were also widely used
to change the characteristics of plastics,
adhesives, paints, and to make carbonless
carbon paper. Today PCBs are used
primarily as coolant insulation fluids in
electrical transformers and capacitors.
The toxicity of these substances was
first recognized as a problem by scientists
in Sweden in 1966. Further attention was
focused on this problem in March, 1968
after 1,000 people in Japan were
accidentally poisoned by eating cooking oil
contaminated with PCBs. Victims were
afflicted with skin lesions, blindness,
hearing loss, jaundice, and abdominal pain.
A few birth abnormalities were also linked
to this poisoning episode. Manufacture,
transportation, and use of PCBs were
drastically reduced and restricted by
manufacturers in 1971.
CAUTION
CONTAINS
PCBs
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Coou Guord Notional fteiponie Center
800 424-6602
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Federally required
label for
certain PCB items.
PCB manufacture, processing,
distribution, and use in an open system
were prohibited in the U.S., in 1979,
except by special permit from EPA. But
recent environmental tests have detected
PCBs all around the globe— in the fatty
tissues of Arctic polar bears, in Great
Britain's rainfall, in ocean and freshwater
fish, and in the milk of nursing mothers.
Especiallly high PCB concentrations have
been detected in the Great Lakes region, in
North Atlantic States, and in southeastern
coastal States. PCBs are found in soil, air,
water, and in many living organisms.
Because PCB molecules do not break down
easily into other, less toxic molecules, they
are expected to remain a significant
contaminant in the environment for the
undetermined future. Although great
care is now being taken to prevent the
introduction of PCBs into the natural
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ecosystem, they continue to enter the
environment when wastes are improperly
incinerated or disposed of. PCBs in the
atmosphere are carried around the world
and reenter land or water in a random pattern.
Another instance of accidental
introduction of a toxic substance occurred
when PBB, a toxic fire-retardant chemical,
was inadvertently mixed with cattle feed in
Michigan. Before the mistake was realized,
PBB had been introduced into dozens of
farms and had found its way into the soil,
water, livestock, and crops. Thousands of
farm animals were destroyed and
numerous farms went bankrupt as a result.
Farm families experienced unusual
physical symptoms— fatigue, muscle
aches, rashes, and irritability. Although
this accident was a one-time occurrence,
PBB levels are still significant at many of
the farms involved, and trace amounts are
detectable in many individuals who
consumed the products of these farms.
How are people exposed to toxic substances?
People can be exposed to toxic
substances through the presence of these
substances in food, air, water, soil, or in
man-made objects. Toxic substances
frequently are released into the environ-
ment by the discharge of liquid wastes into
waterways, the disposal of wastes in
landfills or dumps not properly designed
for the containment of toxicants, or the
transport of gases and dust through the
air. Many toxic materials tend to
accumulate in living things and are passed
on through the food chain, so that the top
predators— flesh-eating fish, birds, and
mammals— receive a concentrated dose of
such materials. If the substance is one
that accumulates in the body, as many do,
an organism may take in smaH amounts of
the substance over long periods of time
and accumulate a large enough dose to
cause health problems.
Some of these toxic contaminants that
have occurred in foods include lead,
mercury, pesticides, PCBs, and toxic
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substances produced by the growth of
certain bacteria in foods (for example,
ptomaine or botulism). Fish accumulate
chemicals from plant and animal life they
eat. Fruits or vegetables may contain
residues of pesticides that were applied to
the crop. Improper handling of perishable
foods may cause bacterial growth, which
produces toxic by-products. The
commercial food industry and the U.S.
Food & Drug Administration have
established a regulatory network to help
prevent contaminated foodstuffs from
reaching the commercial market.
Some people are exposed to toxic
substances in their workplace. Such
occupational exposures are monitored and
regulated by the U.S. Occupational Safety
and Health Administration. Exposure to
toxic substances in the workplace may be
connected with industrial jobs that involve
the use or manufacture of chemicals or the
mining of such materials as asbestos or
uranium.
Rhesus monkeys are
used by University of
Wisconsin researchers
to study PCB's effects.
Infant far left is a
control; other infant's
mother was fed just 1
ppm PCB in her diet
while pregnant and
while nursing this baby.
The mother showed no
ill effects; this infant
died at 4 1/2 months.
What can toxic substances do?
Toxic substances can cause a great
variety of problems to plants, animals, and
humans. These effects can be classified
as either short-term (rashes, headache,
nausea) or long-term (cancer, birth defects,
permanent damage to an organ, or death).
Short-term effects result from the acute
exposure of the individual to one or more
toxicants; these appear quickly and are
usually reversible. When the exposure to
the toxicant(s) is stopped, the effects
generally disappear in a reasonably short
time and full health is recovered. Many of
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the long-term effects that can result from
exposure to toxic substances are
permanent. They may involve genetic
mutations (permanent changes in hereditary
characteristics), irreversible damage to
certain organs such as the eyes or the
liver, or cancer. Long-term effects may not
show up until many years after the
exposure, or they may appear in the
offspring of the individuals exposed. The
list of known toxic substances is large, and
much remains to be learned about the long-
term effects of exposure to toxic
substances.
Any harmful effect of a chemical
substance is related to its relative toxicity,
which is the amount of the substance
needed to produce a toxic effect compared
to other toxic substances. The smaller the
lethal dose of a chemical, the higher its
relative toxicity. Other factors — amount
and duration of exposure, the sensitivity of
the individual to that chemical — can
affect the type and degree of an
individual's reaction to exposure. For
instance, the substances contained in
cigarette smoke are known to cause lung
cancer in humans, but not all people who
smoke will contract lung cancer. This
seems puzzling at first, but it illustrates
that the toxic activity of a substance is not
predictable and is instead subject to
interaction with many other factors, some
of which are not yet well understood.
The fact that we do not know
everything about what toxic substances
can do is a source of anxiety and unease
in the general public. It may seem that
every time one picks up a newspaper
something else has been found that
causes cancer. In fact, while many
unknown health hazards are connected
with living in a technological society, the
chances of living a long and healthy life,
free from severe toxic effects, are great. It
is important to cautiously evaluate and
control toxic substances by a rational, step-
by-step approach. Exaggerated accounts of
dangers that imply everything causes
cancer or is harmful do little more than stir
up people's fears.
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What can be done to protect us
from toxic substances?
Some important things that are being done
by EPA in cooperation with State and local
governments, international commissions
and responsive industries are:
• comprehensive testing of new chemical
substances before they are introduced
into commerce.
• evaluation of known toxic substances
and their interactive effects.
• development of less-hazardous
substitutes for substances that are
unacceptable. These substitutes may be
biodegradable (quick to break down),
less toxic, or not subject to accumulation
in living organisms.
• innovations in the use of such toxic sub-
stances as pesticides, such as reducing
the quantity of the substance recom-
mended to do the job. Integrated Pest
Management Programs, for example,
develop ways to use smaller amounts of
pesticides at specific points in the life
cycle of the pest in order to produce
similar results to the applications of
large amounts of pesticide without re-
lation to the organism's life cycle.
• development of industrial waste exchanges
with special emphasis on the re-use of
toxic waste as a raw ingredient in the
manufacture of a new product.
• establishment of safe, carefully monitored
disposal sites for toxic materials.
* expansion of research on the long-term
effects of toxic substances on human
health.
• increased public education and infor-
mation-dissemination programs on
toxic substances.
Toxic substances are a part of our
world. They have been produced in the
past, and many will be produced in the
future. If toxic substances must be used
and disposed of, as it appears they must, it
is important that they be handled safely,
both for our own and for future
generations' sakes.
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FEDERAL LAWS THAT REGULATE
TOXIC SUBSTANCES INCLUDE:
Toxic Substances Control Act, 1976.
Authorizes the U.S. Environmental Protection
Agency (EPA) to inventory industry data on
production, use, and health effects of chemicals
and to regulate the manufacture, distribution,
use, and disposal of chemical substances.
Clean Water Act 1972; amended 1977.
Requires EPA to set toxic pollutant effluent
standards and to grant discharge permits.
Clean Air Act, 1970; amended 1977.
Empowers EPA to regulate hazardous air
pollutants and to set emissions standards.
Resource Conservation and Recovery Act,
1976.
Gives EPA the authority to regulate the
treatment, storage, transport, and disposal of
hazardous wastes.
Occupational Safety and Health Act, 1970.
Enables the Occupational Safety and Health
Administration to regulate exposure to
hazardous substances in the workplace.
Federal Food, Drug, and Cosmetics Act
(plus amendments), 1938...1976.
Provides the Food and Drug Administration with
the authority to set tolerances for contaminants
in commercial foods, drugs, and cosmetics, and
to ban unsafe products.
Federal Insecticide, Fungicide, and
Rodenticide Act and the Federal
Environmental Pesticide Control Act, 1972.
Authorizes EPA to register all pesticides and
uses, issue permits to applicators, and cancel or
suspend specific pesticides or uses if they are
deemed unduly hazardous.
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Is it costly to control toxic substances?
It is indeed expensive for government
and industry to perform tests, develop
premanufacturing notifications, and
compile an inventory of chemicals.
Increased costs to the manufacturer who
must control toxic substances may be
passed on to the consumer in higher
prices. People may not understand— or be
happy— when a popular product that may
also be toxic disappears from the
marketplace or increases in price. It also
costs more in the short-term to dispose of
toxic substances in an environmentally
sound manner. Confined disposal areas or
high-temperature incinerators are some of
the approved methods of disposal, and they
are expensive.
But the costs that are harder to
determine are those of not regulating toxic
substances and instead suffering the long-
term consequences, both in health and in
damage to the environment. One example
of a short-term economy that led to
enormous financial burdens to society and
industry was the disposal of hazardous
chemicals in the Love Canal area by a
major chemical company in the 1940s.
Although care was taken to prevent the
escape of the toxic materials stored there,
the safeguards did not go far enough. The
containment system was breeched, and 30
years later toxic chemicals were found to
have escaped and contaminated local soil
and water. People have been evacuated
from their homes because of the effects of
toxic pollutants, and large areas of
developed land are now unusable. The
costs in human health problems and birth
defects that may be linked to this one
situation are high, and they are impossible
to define in hard figures. The human
tragedy is real. In short, the costs of
preventive measures seem small compared
to the damage.
Other instances of toxic substance
pollution that involve human injury include
the 1977 contamination of dozens of city
water systems in and around Philadelphia
by carbon tetrachloride accidentally mixed
with process chlorine; mercury poisoning
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in Rockford, Illinois in 1974, which
occurred when mercury from an open
dump leached into a farm well and
affected humans and livestock; and the
pollution of rivers and water systems near
Little Sandy River, Kentucky in 1977, when
railroad cars carrying acrylonitrile derailed
and ruptured, spilling their contents and
contaminating the Ohio River.
It is important to learn from such
experiences. More stringent requirements
for the disposal of toxic wastes— properly
engineered and constructed disposal areas,
high-temperature incineration or more
stringent regulation of transportation and
distribution of toxic substances— could
have prevented many of these problems. If
we spend a moderate amount of money to
prevent such disasters, we will not be
faced with the incalculable costs of toxic
pollution in the future.
Private citizens and environmental
organizations have been very important in
the past in identifying toxic substance
problem areas and prompting regulatory
action. You can become involved in the
protection of the environment from toxic
pollutants. Your ideas are important — the
problems involved are complex and require
difficult decisions. It is important that
citizens become part of the decision-
making process.
So GET INVOLVED!
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Become informed. Keeo uo-to-date on
DATE DUE
uiTutwil .1. /wc.i but1 ..... uiin> 01 in your
workplace. As a concerned individual, you
have an important role in the control of
toxic substances. These are important
things you can do:
participate in public meetings and
forums.
avoid the unnecessary use of dyes and
other toxic substances in paper products.
promote public education about toxic
substances, help to schedule educational
events, and encourage schools to in-
clude environmental problems and
solutions as part of their courses of study.
work for legislation that ensures better
control of toxic substances.
reduce household use of toxic products,
such as pesticides. Ask yourself: Do I
really need to use this potentially toxic
product? Use such products cautiously
and dispose of them properly.
get answers to your questions. If you
think that an incident of toxic pollution
may be occurring, ask questions — of
your local or State pollution control
agency or U.S. EPA. Find out the facts, see
what's being done, and follow through.
For more information from EPA, call (31 2)
353-2072.
US EPA. Regjon V. Graphic Arts. 1979
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