Risk/Benefit Balancing Under FIFRA
Risk/Benefit Balancing Under FIFRA
The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) governs EPA's
regulation of pesticides. FIFRA requires that all pesticides intended for use in
the United States be registered (licensed) by EPA to ensure that they do not
cause "unreasonable adverse effects on man or the environment". FIFRA defines
unreasonable adverse effects as "any unreasonable risk to man or the
environment, taking into account the economic, social, and environmental costs
and benefits of the use of any pesticide." Pesticides may pose some risk because
they are meant to kill or control insects, weeds, rodents, and other pests. But
even though pesticide use entails some risk, pesticides provide substantial
benefits to society. Hence, FIFRA, unlike other environmental statutes
administered by the Agency, requires EPA to balance these risks and benefits in
the pesticide decision making process.
In order to be able to balance risks and benefits, EPA conducts complex risk and
benefits assessments that employ the best scientific and economic analyses
currently available. FIFRA authorizes EPA to conduct such full and public
risk/benefit analysis of pesticides through its Special Review process or under
circumstances where data show that a pesticide may pose an imminent hazard to
human health or the environment. These reviews are initiated on the basis of
adverse human or ecological effects data which come to the Agency's attention
subsequent to the initial registration of the pesticide. A Special Review may
result in cancellation of some or all uses of the pesticide, the imposition of
risk reduction measures such as protective clothing, or continued registration
with no changes.
This fact sheet describes both risk/benefit analysis, and how it was applied to
a recent EPA decision on whether or not to permit the continued use of a problem
EPA's basic approach to evaluating pesticide risk is conservative and protective
of public health. These are four steps in the risk assessment process: hazard
identification, exposure assessment, dose/response assessment, and risk
The objective of hazard identification is to assess the nature of any adverse
health effect that may be caused by the pesticide based primarily on the results
of laboratory studies conducted with animals. For example, is the chemical an
eye irritant, does it cause acute poisoning, does it cause birth defects, does
it cause cancer?
Once the type of hazard has been identified, the exposure must be assessed. This
involves estimating the level, duration, frequency and route of exposure. For
example: Are people who often mix and apply large amounts of a pesticide
overexposed? Is there risk to people who consume foods and drink water
containing residues of the pesticide? Will use of the pesticide affect the
non-target organisms, including endangered animal and plant species?
Dose/Response Assessment and Risk Analysis
The dose/response assessment explores the relationship between the level of
exposure and the occurrence of an adverse effect. Since epidemiological studies
with reliable quantitative data on exposure are rarely available, the Agency
must rely on the results of experimental - animal studies to estimate
dose/response relationships. EPA extrapolates from animal studies to potential
effects on humans, and from exposures at high doses in those animal studies to
the substantially lower doses to which humans are typically exposed. Obviously,
this involves uncertainties; EPA is quite conservative in resolving them.
For almost all chemically-related toxic effects (such as birth defects,
reproductive, or non-oncogenic chronic effects), the highest dose level at which
the effect is not observed in the animal study (No Observable Effect Level or
NOEL) is determined and an uncertainty factor (typically 100 or more) is applied
to establish a human exposure level that will pose essentially no human risk.
For example, an animal study may show that at 1000 milligrams of the substance
in the daily diet of a 1 kilogram body weight test animal (1000 mg/kg/day), the
animal showed no adverse effects. By applying a 100-fold safety factor, daily
exposure of a human to 10 milligrams per kilogram of body weight would be
considered to be safe for a human. In conducting pesticide risk assessments, EPA
makes a practice of evaluating all potentially toxic effects, but generally
focuses its quantitative risk/benefit balancing process on the effect observed
at the lowest dosage level.
Where animal studies indicate that the pesticide chemical has induced cancer at
relatively high dose levels, EPA ordinarily presumes that there is no dose at
which some level of carcinogenic effect would not be observed. (This presumption
sometimes could perhaps be overcome by extremely complex and costly studies, but
usually overcoming the presumption is practically impossible.) Thus, EPA uses a
mathematical model that assumes some effect could be caused by any dose, even
one at a very low level. Such a model expresses the worst-case qualitative
carcinogenic "potency" of the pesticide, or the worst-case probability that a
given low dose will produce a response in the animal species.
As an index for regulatory decisions involving carcinogens, EPA's stated policy
is that lifetime incremental cancer risks from exposure to a pesticide in the
diet generally should not exceed one-in-one million or 0.000001 (1 x 10 to the
minus 6) -- meaning one-in-one million risk over and above the background cancer
risk of 1 in 4. This is the concept of "negligible" risk applied by EPA and the
Food and Drug Administration.
Finally, the risk is analyzed by integrating the above factors. This usually
involves extrapolating exposure in animals to humans. It is scientifically,
legally, and ethically impracticable in most cases to do experiments to show
whether humans would have different responses to chemical exposure than test
animals. Thus, EPA ordinarily assumes that human response is similar to that of
EPA seeks to express a risk qualitatively and, where appropriate,
quantitatively, and to give some perspective to the risk by summarizing the
strengths and weaknesses of the supporting data and assumptions. Through risk
analysis, the Agency is able to determine areas where additional data may be
needed or where regulatory action may be warranted.
In deciding whether to cancel a pesticide, EPA conducts benefits assessment. A
benefits assessment follows guidelines that take into account both biological
and economic factors. Biological factors involve information about target pests
on each site or crop. Economic factors involve the effects of various pest
control strategies on the various businesses which produce and distribute
commodities to the consumer. Economic impacts are dependent on the treated
commodity or registered use sights of the chemical in question. So that means
that EPA must do a benefits assessment for each registered use sight. One
Special Review chemical can therefore lead to dozens or even scores of benefits
assessments. Sometimes EPA must tailor its general approach to the particular
pesticide and market conditions encountered. A benefits analysis includes:
Benefits are specific to each use site -- for example, corn, soybeans, or
tomatoes, etc. The estimation of benefits derived from the use of a given
pesticide is a multi-step process. The first step in this process is the
identification of the pesticide's use (i.e., agricultural,
industrial/commercial, or home use), and the principal pest(s) that are
controlled through its application (e.g., insects, weeds, rodents).
Next, EPA takes a comprehensive look at the problem by developing a thorough
understanding of the pest populations, the effectiveness of chemical and
non-chemical alternatives, the geographic distribution of the pest problem,
potential crop yield impacts, and alternative use practices which might mitigate
the risk. In other words, the process Starts with gathering basic usage and
product performance data in order to determine how important the chemical really
is to the production of any crop from corn to mint.
These data are obtained through comprehensive literature searches, data bases
created and maintained by EPA, and extensive communications with pesticide
users. The latter involves requesting information from pesticide applicators,
other government agencies (the Departments of Agriculture and Interior),
scientists from state land grant universities, and organizations representing
various user groups. When little or no empirical data exist, the Agency relies
upon the experience and observations of pesticide applicators, scientists
directly involved in studying pesticide effectiveness, and, to some extent,
independent agricultural consultants. These data are by no means easy to obtain
and sometimes require literally scores of telephone calls, etc. But the Agency
is committed to obtaining the most comprehensive, accurate, and up-to-date
The next step of a benefits assessment is to express the biological impacts of
yield loss, reduced crop quality, and alternative pest control methods in
economic terms. The key question here is, will it cost more to produce the crop?
EPA normally evaluates several types of economic impacts. The first step is to
determine the relative cost of alternative pest control strategies. In some
cases, EPA finds that there are relatively minor economic impacts, because cost
effective substitutes (chemical and non-chemical) exist and are readily
available. However, in other cases equally effective alternatives do not exist.
In this scenario users may have to modify their current use practices, changes
which often result in higher costs of production for relevant agricultural and
non-agricultural goods and services.
An increase in production cost can be passed down to intermediate processors and
ultimately to consumers in the form of higher food prices or more costly control
of pests in the home. In determining economic impacts, EPA takes into account
such influences as agricultural subsidies, quotas, or allotments, supply and
demand factors, and international trade issues.
The Agency estimates both short- and long-term impacts at the user level. This
analysis accounts for the net impacts to producers/suppliers by examining
economic effects on users and nonusers of the pesticide under review. Based on
this information short- and long-term effects in down-stream markets (i.e.,
processors, distributors, consumers) can also be estimated. Potential
local/regional impacts are also identified as part of this analysis. These local
effects may result from movement of economic activity to foreign markets, or to
other areas of the country where pest infestation is not a problem (and
therefore pesticide availability is relatively unimportant).
AN ILLUSTRATION OF RISK/BENEFIT BALANCING -- DINOSEB
To illustrate this highly complex process, consider the case of the herbicide,
dinoseb. In October 1986, EPA issued a formal notice of intent to cancel and
deny all registrations for pesticide products containing dinoseb.
Simultaneously, EPA issued an emergency suspension order to immediately stop
dinoseb use during the time to complete the cancellation proceedings. These
regulatory actions were based on the risk/benefit balancing scenario described
In assessing the risks of exposure to dinoseb, the first step involved
identifying the hazard, based on the results of animal studies. The hazard
evaluation of dinoseb focused on animal test results indicating that it may
cause birth defects to females exposed to dinoseb during pregnancy, and may also
cause sterility or decreased fertility in males, acute toxic poisoning, and
other potential adverse effects on health and the environment.
EPA estimates potential human exposure based on either actual data or surrogate
data. Surrogate exposure data is simply data from studies of exposure to other
pesticide chemicals (surrogates) that are of similar formulation to, and are
applied in the same way as, the pesticide in question. Appropriate adjustments
in the calculations are made to reflect differences in the rate of active
ingredient applied per area, per hour, etc. In the case of dinoseb, three
exposure scenarios were identified:
- Possible dietary exposure to the public through consumption of food or drinking
water containing residues of dinoseb;
- Occupational exposure to workers who mix, load, and apply dinoseb; and
- LSecondary or coincidental exposure to bystanders, farmworkers, and others who
could be exposed to dinoseb through spray drift, contact with residues in
treated fields, or even contact with contaminated clothing or farm equipment
immediately after dinoseb application.
Dose/Response and Risk Analysis
In assessing the test animal dose/response for birth defects, EPA used an oral
feeding study with rabbits to provisionally set a NOEL at 3 milligrams per
kilogram of body weight per day (mg/kg/day) -- meaning that adverse effects in
test animal offspring were apparent in all oral exposure levels higher than 3
mg/kg/day, the lowest dose administered.
For dinoseb the main risk of concern was the 3 mg/kg/day NOEL for birth defects
in rabbits. EPA compared this NOEL from laboratory studies with expected human
exposure levels to obtain numerical margins of safety (MOS). (NOEL divided by
exposure equals margin of safety, or MOS).
Even when certain "worst case" assumptions regarding dietary exposure levels
were factored into these calculations, the MOS for the risk of birth defects
occurring from eating foods from crops treated with dinoseb was found to be
ample -- over 2700. Similarly, from consumption of drinking water, the MOS was
roughly 2430. However, for workers, in many instances the estimated exposure
levels were equal to or greater than the NOEL of 3 mg/kg/day -- leaving
essentially no margin of safety against the calculated risk of birth defects in
the offspring of pregnant workers handling the pesticide.
The benefits assessment of dinoseb was driven by the risk factors described
above. Based on data from the U.S. Department of Agriculture and other sources,
EPA conducted an assessment of the benefits of dinoseb by calculating the
short-and long-term economic impacts expected to occur if dinoseb were
unavailable for certain registered uses. Dinoseb use sites included
soybeaneveloping fetuses. There was also convincing evidence that exposure to
dinoseb under both exposure scenarios posed additional risks of adverse
reproductive effects in males and acute toxic poisoning. EPA considered a range
of measures to reduce the risk, which included additional protective clothing,
protective farm equipment, lower application rates, and product reformulations.
EPA determined that none of these measures could reduce the risks to reasonable
levels. Therefore, though the benefits of dinoseb were substantial in terms of
monetary value, EPA concluded that risks of exposure to dinoseb clearly
outweighed its benefits, not only in the long-term but also during the interval
of time required to conduct usual cancellation proceedings. Thus, in October
1986 the Agency opted for the most drastic remedial option available under FIFRA
-- emergency suspension, calling an immediate halt to the sale and use of a
pesticide while cancellation proceedings are conducted.
However, in reaching a decision to immediately suspend dinoseb, EPA did not
attempt to evaluate the economic benefits from use of dinoseb for each affected
crop in each geographic region. Rather, the Agency focused on national impacts
and on those crops involving the largest amount of use and percent of the crop
treated. A more extensive analysis would not have been consistent with the
Agency's concern about the imminent hazard to pregnant women exposed to dinoseb.
As a result, however, growers of certain minor crops grown in the Northwest sued
EPA, asserting that the suspension was invalid because EPA did not properly
conduct its benefits analysis and that there were modifications to use practices
less drastic than suspension that would have sufficiently reduced the risk. The
growers also complained that EPA could have delayed the suspension of use of
dinoseb on their crops, which would not have occurred until several months after
the suspension order was issued, while EPA completed the benefits assessments
for their uses. (The suspension of the major uses of dinoseb, such as peanuts
and potatoes, was never challenged.) A district judge agreed with the plaintiffs
and issued an order allowing the use of dinoseb on the minor crops if a series
of use precautions were observed.
An appeals court later ruled that the district judge had no authority to modify
the suspension order by imposing conditions of use, but by then the use had
already occurred. Meanwhile, EPA completed its assessment of the benefits of all
dinoseb uses in preparing for the cancellation hearing. However, all the
registrants of dinoseb eventually agreed to withdraw their registrations, making
both a cancellation proceeding and further court proceedings moot.
Some of the other cases interpreting the suspension provisions of FIFRA are not
consistent with the results in the Northwest dinoseb suspension case. However,
if FIFRA is not amended or clarified, the need to fully assess economic benefits
prior to emergency action could prevent EPA from taking timely action to protect
public health. Under President Bush's food safety plan announced in October
1989, EPA would have the flexibility to order a suspension when there is
substantial risk to human health without consideration of economic benefits.