Quantitative risk assessment is now widely used throughout government
and industry to "prove" that a proposed chemical exposure will produce
only "acceptable" damage to humans. For example, a quantitative risk
assessment for a proposed incinerator will "prove" that "only" one
person out of a million exposed people will be killed each year by air
pollution from the incinerator. No scientists actually believe that
humans have sufficient knowledge to measure risks from toxic chemicals
accurately or precisely or completely. For example, the U.S.
Environmental Protection Agency's Science Advisory Board recently said
that risk analyses "always will be imperfect tools" and "No matter how
much the data and risk assessment techniques are improved... EPA's
judgments [based on risk assessment] will entail a large measure of
This inherent uncertainty in risk assessment means that clever people
can manipulate data, and can manipulate unspoken assumptions, to
achieve any quantitative result they choose. In fact, it is common for
risk assessors to select the goal that their risk assessment is
supposed to achieve (onein-a-million is a common goal), then to
manipulate the data and assumptions to come up with the "right" answer.
The result is usually expressed as a single number and such numbers
look very precise and scientific even though they may be based only on
estimates or guesses, or may even have been fabricated.
For the past six years, Mary O'Brien has edited the JOURNAL OF
PESTICIDE REFORM and has served as staff scientist of the Northwest
Coalition for Alternatives to Pesticides in Portland, Oregon. For six
years she has seen risk assessments used by scientists employed by
polluters to justify exposing people to toxic chemicals.
"Worker inhalation and absorption of workplace toxics is approved via
risk assessment," she says. "The spraying of pesticides on
schoolgrounds, roadsides, over urban areas and forests, and on the
nation's food supply is dubbed acceptable via risk assessment. The
degradation of our drinking water supplies, aquifers, and air is
approved via risk assessment."
Ms. O'Brien believes that risk assessment should be put on the back
burner and, in its place, we should substitute a formal search for
alternatives. Instead of asking "How much human health damage is
acceptable?" we should start asking "How quickly can we install or use
practices that will result in the least use of, and exposure to, toxic
The basic goal of a risk assessment is to evaluate the potential
consequences of a decision, recognizing that much necessary information
is not available and may never become available. Numerous wise
approaches are available to replace risk assessment, and they must
often be used in combination with each other:
1. Qualitative risk assessments. These methods involve looking at
worst-case environmental and social consequences of inadequate
information, missing information, non-scientific information
(complaints by workers about their experiences on the job, for
example), epidemiological information, and suspicions about cumulative
effects. A "chemical profile" that looks at all aspects of a chemical
(known and unknown) can be extremely revealing. (See RHWN #169.)
Instead of spending vast sums on risk assessment for particular
chemicals, perhaps a review of available information is sufficient to
say, "This chemical seems to cause problems among laboratory animals
and workers. We don't know very much about its mechanisms of toxicity,
we'll never know what it does to people in combination with the
hundreds of other chemicals they're exposed to, so we'll never be able
to produce a convincing risk assessment. Therefore instead of producing
a scientific sham risk assessment let's seek alternative ways of
getting the job done (whatever the job is), reducing or even
eliminating use of this potentially harmful chemical."
2. Labeling products and processes with all toxic chemicals used. If
all workplace processes are labeled (every pipe, every vat, every drum,
as is required by the New Jersey Worker and Community Right to Know
Law), and all consumer products are labeled with their toxic
ingredients, citizens can at least make informed choices about what
they want to expose themselves to. Prop 65 in California requires that
any person who knowingly and intentionally exposes another person to a
carcinogen, or to a chemical known to cause reproductive hazards, must
give clear and reasonable warning to the person exposed. Let the
consumer be informed.
3. Some chemicals can be phased out by regulating particular compounds
or particular processes. DDT has been banned for sale in the U.S.;
Sweden has given its pulp and paper mills a deadline for near-zero
discharge of chemical compounds containing chlorine; if the "Big Green"
initiative passes in California this November, use of carcinogenic
pesticides on California food will end within 5 years. Just say "no" to
4. Require honesty about ignorance in quantitative risk assessments.
Where quantitative risk assessments are used, they could be
supplemented by formal statements about their shortcomings. Such
statements could include standards that have been set elsewhere to
control this chemical; the kinds of scientific tests that have not been
done on a chemical (for example, studies of chronic nerve damage);
whether infants, old people, and chemically sensitive people were
considered in the assessment; whether degradation byproducts of the
chemical were considered in the assessment (for example, DDT breaks
down in the environment to a chemical called DDE, which is more toxic
than DDT); what is not known about chemicals in combination with each
other. People need to know that, with toxic chemicals, the unknowns are
much larger than the knowns.
5. Require an official search for alternatives to toxics. Often, a
formal search for alternatives to toxics will make a risk assessment
unnecessary. "Anyone who sees chlorine-free paper products (e.g.,
magazines, copy paper, toilet paper, tampons) available in Sweden and
Austria realizes the absurdity of estimating how many dioxin-laden fish
caught below a chlorine-using pulp mill constitute 'acceptable risk',"
says Mary O'Brien.
"The first step of admitting that it would be desirable to reduce use
of pesticides and other toxics is generally the hardest for most
agencies or industries," she says. But getting agencies and industries
to state such a preference is crucial. Once we reach agreement that
toxics use reduction is desirable, then the formal search for
alternatives can be initiated and we can stop relying on the narrow,
deceptive "science" of quantitative risk assessment.
 REDUCING RISK: SETTING PRIORITIES AND STRATEGIES FOR ENVIRONMENTAL
PROTECTION (Washington, DC: Science Advisory Board [A-101], U.S.
Environmental Protection Agency [401 M St., Nw, Washington, DC 20460],
September, 1990, pg. 16. This 26-page summary report is available upon
written request from the Science Advisory Board at the address given
(don't forget the A-101); and be sure to ask for the three separate
Appendices as well.
To understand the federal government's viewpoint toward risk
assessment, you might want to get the Council on Environmental
Quality's book RISK ANALYSIS: GUIDE TO PRINCIPLES AND METHODS FOR
ANALYZING HEALTH AND ENVIRONMENTAL RISKS. Available for $17.50, plus
$3.00 shipping, from National Technical Information Service (ntis):
phone (703) 487-4650. Ask for document Pb 89-137772.
[We have taken material from two articles by Mary O'brien writing in
the JOURNAL OF PESTICIDE REFORM (JPR), Vol. 8 No. 1, pgs. 7-13 and Vol.
10, No. 1, pgs. 2-6. We urge readers to subscribe to JPR: individuals,
$15/yr; institutions, $25/yr from: Northwest Coalition for Alternatives
to Pesticides, P.O. Box 1393, Eugene, Or 97440. Back issues are
available for $3 each, or $10 for a year's worth.]
Descriptor terms: risk assessment; journal of pesticide reform; mary
o'brien; workers; occupational safety and health; labeling;