12
Environmental and Health
an unreasonable risk. When EPA determines that an unreasonable risk
exists, it issues a "rebuttable presumption against registration" (RPAR),
and provides the opportunity for the registrant to provide evidence before
a final decision is made. Examples
of canceled registrations include
DDT, aldrin/dieldrin, 2,4,5-T/silvex, kepone, mirex, and ethylene
dibromide.
The Toxic Substances Control Act was designed to close all the
loopholes in the environmental protection and chemical manufacture and
use laws. It gives EPA broad authority to regulate chemical substances
without regard to specific use (e.g., food, drug cosmetic) or area of
application (e.g., food crops) if they present a hazard to health or the
environment. The law controls the chemical at its source before it is
distributed into the environment and public. Excluded from coverage
under TSCA are food, food additives, drugs, or cosmetics regulated
under the FFDCA; pesticides regulated under FIFRA; and nuclear
materials regulated by the Atomic Energy Act.
Other federal laws control the release of pollutants into the
environment or workplace. However, it is very difficult to monitor and
set emission standards on substances that only enter the environment in
very small quantities. A need
was seen to control some substances
before they are dispersed into the environment. Chlorofluorocarbons,
(CFC) used as a propellant in spray cans illustrate this need. When
released, CFCs are so stable that they do not react with anything until
they diffuse upward to the stratosphere. There they are decomposed by
ultraviolet radiation and enter into a chain reaction to destroy ozone
molecules. Ozone depletion enables more solar ultraviolet light to reach
the earth, thereby increasing the incidence of skin cancer as well as
influencing climatic changes. Since chlorofluorocarbons are not
classified as air pollutants and pose no hazard in the workplace, there
was for many years no means of regulating their use. The need to
control toxic substances at the point of manufacture was therefore
identified by congress in the passage of TSCA.
TSCA also specifically bans the manufacture of polychlorinated
biphenyls (PCB). In addition, chemical manufacturers and importers
must provide EPA with a Premanufacture Notice (PMN) which provides
available health and environmental effects data at least 90 days prior to
the manufacture and sale of any chemical. EPA can approve the
chemical, request further testing, condition the manufacture and sale of
the chemical, or prohibit its manufacture. The law is often thought of
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