Environmental Engineering Reference
In-Depth Information
proposed or existing chemical or technology, we should
take action to prevent or reduce the risk instead of wait-
ing for more conclusive (sound or consensus science)
evidence.
Under this approach, those proposing to introduce
a new chemical or technology would bear the burden
of establishing its safety—a guilty-until-proven-innocent
approach. This means two major changes in the way we
evaluate risks. First, new chemicals and technologies
would be assumed to be harmful until scientific stud-
ies can show otherwise. Second, existing chemicals and
technologies that appear to have a strong chance of
causing significant harm would be removed from the
market until their safety can be established.
Some movement is being made in this direction,
especially in the European Union. In 2000, negotiators
agreed to a global treaty that would ban or phase out
use of 12 of the most notorious persistent organic pollu-
tants (POPs), also called the dirty dozen. The list in-
cluded DDT and eight other persistent pesticides,
PCBs, and dioxins and furans. New chemicals would
be added to the list when the harm they could poten-
tially cause is seen as outweighing their usefulness.
This treaty went into effect in 2004.
Manufacturers and businesses contend that wide-
spread application of the precautionary principle
would make it too expensive and almost impossible to
introduce any new chemical or technology. They argue
that we can never have a risk-free society.
Conversely, proponents of increased reliance on
the precautionary principle say that it will encourage
innovation in developing less harmful alternative
chemicals and technologies, and in finding ways to
prevent as much pollution as possible instead of rely-
ing mostly on pollution control. We can never have a
risk-free society. But proponents believe we should
make greater use of the precautionary principle to re-
duce many of the risks we face.
ing options and making decisions about reducing or
eliminating risks ( risk management; Figure 14-2, right),
and informing decision makers and the public about
risks ( risk communication ).
Statistical probabilities based on past experience,
animal testing and other tests, and epidemiological
studies are used to estimate risks from older technolo-
gies and chemicals. To evaluate new technologies and
products, risk evaluators use more uncertain statistical
probabilities, based on models rather than actual expe-
rience and testing.
Figure 14-11 lists the results of a comparative risk
analysis, summarizing the greatest ecological and
health risks identified by a panel of scientists acting as
advisers to the EPA.
Comparative Risk Analysis
Most Serious Ecological
and Health Problems
High-Risk Health Problems
• Indoor air pollution
• Outdoor air pollution
• Worker exposure to industrial
or farm chemicals
• Pollutants in drinking water
• Pesticide residues on food
• Toxic chemicals in consumer products
High-Risk Ecological Problems
• Global climate change
• Stratospheric ozone depletion
• Wildlife habitat alteration and destruction
• Species extinction and loss of biodiversity
Medium-Risk Ecological Problems
• Acid deposition
• Pesticides
• Airborne toxic chemicals
• Toxic chemicals, nutrients, and
sediment in surface waters
x
H OW W OULD Y OU V OTE ? Should we rely more on the pre-
cautionary principle as a way to reduce the risks from chemi-
cals and technologies? Cast your vote online at http://biology
.brookscole.com/miller11.
Low-Risk Ecological Problems
• Oil spills
• Groundwater pollution
• Radioactive isotopes
• Acid runoff to surface waters
• Thermal pollution
14-5
RISK ANALYSIS
Science, Poverty, and Lifestyles:
Estimating Risks
Scientists have developed ways to evaluate and
compare risks, decide how much risk is acceptable,
and find affordable ways to reduce it.
Risk analysis involves identifying hazards and evaluat-
ing their associated risks ( risk assessment; Figure 14-2,
left), ranking risks ( comparative risk analysis ), determin-
Figure 14-11 Science: comparative risk analysis of the
most serious ecological and health problems according to
scientists acting as advisers to the EPA. Risks under each
category are not listed in rank order. Critical thinking: which
two risks in each of the two high-risk problems do you believe
are the most serious? (Data from Science Advisory Board,
Reducing Risks, Washington, D.C.: Environmental Protection
Agency, 1990)
Search WWH ::




Custom Search