|
Considering questions of environmental risk as we take action
against pests has become an increasingly important issue.
Environmental risk involves technical understandings of risk, public
perceptions, and public influence, as well as fundamental questions
about the principles and goals for pest management. Although some
questions of risk date back to the origins of the concept of pest
management, many modern issues are relatively recent developments.
This chapter will briefly address environmental risk in pest
management and will try to highlight key references that provide more
detailed information. One important point to make at the outset is
that much work on environmental risk in pest management is ongoing,
and many of the issues we will discuss retain considerable
controversy and are by no means fully developed.
A key question to be asked is if pest management even needs to
address issues of environmental risk. As Perkins (1982) has pointed
out in his seminal book, Insects, Experts, and the Insecticide
Crisis, the goal of many workers in pest management is to address the
needs of farmers. As we consider issues in environmental risk, we
must recognize that there can be conflicts between the needs of
agricultural producers and the concerns of society in general. Is it
part of the explicit goals of pest management to deal with these
greater societal concerns on issues like environmental risk? In other
words, is pest management only about dealing with pests and
maintaining profitability or are other, noneconomic considerations
important?
We, like many individuals working, thinking, and writing about
pest management, believe pest management must address environmental
risk. However, this is not a universally held viewpoint. In our view,
goals of pest management include economic sustainability through
minimizing the economic impact of pests, ecological sustainability
through employing management tactics to minimize selection pressure,
and environmental sustainability impact of management tactics on the
environment. It is this latter point, of course, that is the focus of
these comments, and it seems an important one to make about any
technology. While society may be willing to accept some environmental
deterioration in association with certain technologies (air pollution
associated with generating power and use of automobiles is an obvious
example), nevertheless, we would like to have technologies with
minimal impacts. Because pest management is a philosophy addressing
how we should employ technologies against pests, it follows that
minimizing environmental impacts of those methods should be one of
our goals.
We will consider this question in more detail, but you should be
aware of a number of important references. Pimentel and Lehmen (1993)
offer various perspectives on issues of pesticides and environmental
quality. Another good book on broader questions of risk and risk
perspective is a recent volume by Cothern (1995), which discusses
decision making relative to risk perception and ethical implications
of questions about risk. Also, the National Research Council (1989)
publication Improving Risk Communication is another valuable
reference on fundamental definitions of risk.
Our own work on environmental risk and IPM addresses areas
including national pesticide policies (Higley et al. 1992), pesticide
risk communication (Peterson and Higley 1993), and reducing risk
through IPM. Regarding pest management broadly, Pedigo and Higley
(1992) and Higley and Pedigo (1993) offer perspectives on improving
responsiveness to environmental questions through consideration of
the economic injury level. Another approach employing the economic
injury level is that of Higley and Wintersteen (1992) in which they
present an environmental EIL (which we will discuss in more
detail).
These references are only a fraction of the large literature that
is available on risk, but they do offer a starting place to begin
more detailed investigations. The remainder of this chapter will look
at two issues. First, we will consider what exactly risk is and
discuss the importance of perceptions on risk in defining risk.
Second, we will look at approaches for addressing risk in pest
management, and, specifically, we will consider some new proposals
(in which we've been involved), such as the environmental EIL.
Risk and Risk Perception
What is risk? Why do public perceptions of risk differ from expert
assessments of risk? Is it possible for risk to be an objective
measure, or will it always be subjective? In this section, we will
address these questions; for a more comprehensive discussion see
Peterson and Higley (1993).
Public perceptions of pesticide safety increasingly influence
pesticide legislation and regulation. Unfortunately, although public
concerns about pesticides do, and should, contribute to the formation
of pesticide legislation and policies, perceived risks may contribute
to irrational, even counterproductive, regulations (Higley et al.
1992). Misunderstandings about public perceptions of risk and failure
to address the key issues of risk perception, are important barriers
to consensus about the risks posed by pesticide use.
What is Risk?
Does the number of fatalities associated with a risk solely
represent the magnitude of the risk? Some experts would say yes.
However, risk assessments usually include broader definitions of
risk. For example, is swimming riskier than nuclear power? Yes, if we
consider fatalities alone. (Approximately 3,000 people die each year
from swimming-related accidents in the United States alone.) But,
swimming is not riskier than nuclear power if we consider other
factors.
Although definitions of risk vary, most recognize risk as:
R = P * C (1)
where R is risk, P represents the chance or probability of an
undesirable event, and C represents the adverse consequences of the
event (Lowrance 1980). You might say that risk is a measure of how
often something will happen and how bad it will be. Differences in
risk perception involve different perspectives on both probability
and consequence.
Public Perception
Risk perception research began in earnest soon after the accident
at the Three Mile Island Nuclear Power Plant in Harrisburg, PA.
Researchers were intrigued that expert estimates of risk from
technologies such as nuclear power did not mirror public estimates of
risk from the same technologies. Therefore, risk perception research
seeks to understand how people perceive risk presented by different
circumstances and activities.
The public continually ranks certain risks much higher than
experts. Why is this so? According to Slovic (1987), "Lay people can
assess annual fatalities [from a given factor] if they are
asked to (and produce estimates somewhat like the technical
estimates). However, their judgments of `risk' are related more to
other hazard characteristics (for example, catastrophic potential,
threat to future generations) and, as a result, tend to differ from
their own (and experts') estimates of annual fatalities."
Perceptions of Pesticide Risk
Public perceptions of risk from pesticides usually are greater
than the risks determined by experimentation. Experts determine risk
from pesticides based on empirical estimates of chronic and acute
human and animal toxicity and environmental fate. Although in most
cases human health risks associated with pesticide use are very low,
the public consistently ranks pesticide use as being very risky
(Slovic 1987). Indeed, the public perception of risk posed by most
synthetic chemicals is inordinately great (Hart and Turturro 1987,
Kraus et al. 1992). Too often, people who work with pesticides and
have a more complete understanding of the risks often dismiss public
concerns as irrational or misinformed. Consequently, many technical
people react defensively to public concerns. Even worse, some regard
public fears as so irrational that they do not attempt to explain
risks and the risk assessment process to lay people. This is
dangerous behavior, because the public needs to understand and be
involved in pesticide issues to improve the policy making process
(Higley et al. 1992).
Responses to public concerns by experts are often inadequate,
doing little to seriously address public risk perceptions. A
traditional approach has been to respond to public concerns by
comparing highly visible, well-understood risks to less visible, less
well-understood risks (National Research Council 1989). Some
responses have compared the risks from pesticide exposure to the
risks presented by everyday activities, such as driving an automobile
or riding a bicycle. Although most risk comparison statements by
pesticide experts are more accurate than public perception of the
risks, these responses do little to correct the public's
misconceptions about the unfamiliar risks of pesticide use (Slovic
1987, National Research Council 1989). Most experts fail to consider
the criteria the public actually use to evaluate risks.
Risk Criteria
Although the risks associated with driving an automobile are more
serious, the public perceives using pesticides as being much riskier.
Why is this so? Researchers recently have explored the mental
processes people use to assess risks from many types of modern
technologies and activities. This body of research demonstrates that
lay people use a different set of criteria than experts for
evaluating risk. Specific factors that influence public risk
perception include:
- Control - the ability of the individual or society to control
the risk.
- Catastrophic potential - the possibility of fatalities or ill
effects grouped in time and space as an epidemic.
- Dread - the fear of the possibility of serious delayed
effects, such as cancer. Dread is related to catastrophic
potential, but the impact does not necessarily need to be grouped
in time or space.
- Familiarity - the degree of familiarity lay people have with
risk.
- Equity - the equal distribution of risks and benefits
throughout society.
- Level of knowledge - the general understanding lay people have
with the process or activity posing the risk.
- Voluntariness of exposure.
- Effects on children and future generations - concerns about
possible delayed effects on humans and the environment posed by
the risk.
- Clarity of benefits - represents the awareness and
understanding of the benefits provided by the activity posing the
risk.
- Media attention.
- Trust in organizations or institutions.
The public uses these characteristics to judge the acceptability
of a risk, rather than using risk estimates based on experiments.
Such a view of risk is more encompassing and powerful than simple
estimates of mortality. In addressing risk, we should especially
consider catastrophic potential, control, level of knowledge, and
effects on children and future generations.
One reason the public may view pesticides in food as riskier to
their health than the natural carcinogens in common foods and
beverages is because consumers have no control over the pesticide
content of food. In contrast, people can choose which types of foods
they eat, and, therefore, they have a sense of control over this
activity. Similarly, people may accept the risks from driving an
automobile much more readily than the risks from pesticide exposure,
because they have control over the automobile.
The public also will not readily accept the risk associated with a
potential catastrophe (Slovic 1987). And yet, catastrophic potential
is seldom discussed by the experts. For example, public fear of
nuclear power is largely based on vivid images of millions of
radiation deaths, massive environmental devastation, and threats to
future generations should an accident occur (Slovic et al. 1982).
Consequently, the public's perception of risk from nuclear power is
far greater than the experts'. More to the point, the pesticide
disaster at Bhopal, India, although it was an industrial accident, is
a vivid example of the catastrophic potential of pesticides
(Shrivastava 1987).
The public views pesticides as having both catastrophic potential
and posing a dread risk (Slovic 1987). First, pesticides are feared
because of their possible harmful delayed effects such as cancer.
Second, the public is greatly concerned about environmental damage
caused by pesticide use. It was, after all, Rachel Carson's 1962
book, Silent Spring, documenting the ill effects from pesticide use
that sparked the environmental movement. Widespread knowledge of the
problems with biomagnification and contamination of groundwater by
pesticides and their metabolites, coupled with the reality that
pesticides are among the most extensively broadcast synthetic
chemicals in the environment, makes dread risk a very real concern to
the public.
Coverage of a risk by the mass media can reinforce existing public
risk perceptions (Wilson 1991). Media coverage often reveals the
dangerous activities that are so pervasive in today's technological
world. The mass media provide visual images of risks, enhance the
imaginability of a problem, and concentrate on the human aspects
(Hart and Turturro 1987, Valenti 1987). The media may also remind the
public that they have little or no control over these activities.
The public is unlikely to accept risks from an activity if experts
openly disagree over the magnitude and nature of the risk. Indeed,
the public knows that experts have advocated the use of pesticides
without full knowledge of their potential hazards, DDT being a prime
example. The public views pesticides as risky, in part, because of a
justified lack of confidence in expert opinion. Once the credibility
of experts and government institutions has been damaged, it is very
difficult to regain public confidence (National Research Council
1989). To complicate matters further, the public realizes that
experts can be found to support any position in a risk argument
because attitudes about risk are inherently subjective.
Public perception of risk also is influenced by individual and
group goals, values, and politics (National Research Council 1989).
Some groups may want to see all pesticides banned; other groups may
want less government regulation of pesticides. The goals and values
expressed by individuals in these diverse groups will influence their
risk perceptions. Similarly, members of society do not equally accept
the benefits from a technology (National Research Council 1989).
The understanding, or clarity, of benefits associated with
pesticide use also is considered by the public in conjunction with
pesticide risks. Where benefits relate directly to questions of risk,
for example, accepting one risk (such as pesticides) to avoid a
greater risk (such as tick- or mosquito-borne diseases), benefits may
have a direct bearing on risk perception. More commonly, discussions
of benefits focus on economic impacts or crop yields which the public
does not regard to be as important as health or environmental risks
(Slovic 1990). Assessing benefits is very much a matter of opinion
and because benefits do not directly apply across society,
discussions of pesticide benefits are unlikely to quell public
concerns about pesticide risks.
Conclusions
Much more risk-perception research is needed, especially as it
relates to pesticides. Slovic (1987) eloquently stated that, "Lay
people sometimes lack certain information about hazards. However,
their basic conceptualization of risk is much richer than that of the
experts and reflects legitimate concerns that are typically omitted
from expert risk assessments. Each side must respect the insights and
intelligence of the other." Unless these valid public attitudes
regarding pesticide risks are acknowledged and addressed by experts
and public agencies, conflict over these risks seems inevitable.
Addressing Risk in Pest Management
Tactics and Frequency of Use
Historically, two approaches have dominated the question of
environmental quality in pest management: frequency of use and choice
of management tactic. Regarding frequency of use, many efforts in
pest management are directed at reducing unnecessary management
action (typically, eliminating unneeded pesticide use). The
development of the economic injury level (EIL) and associated
economic thresholds (ET) is one clear reflection of this trend
(Pedigo et al. 1986). In most cases where the issue has been studied,
the use of pesticides is reduced with thresholds. These reductions
are a consequence of conservative attitudes toward protecting crops
with pesticides. Relative to other costs of production, pesticides
often provide relatively inexpensive insurance against catastrophic
losses from pests. However, although thresholds have been important
in reducing frequency of use, it is not an intrinsic feature of EILs
or ETs that necessarily lead to a reduction in use. For example, in
situations where a crop is not intensively managed, such as with
forages or other low-value crops, the use of thresholds can cause an
increase in pesticide use.
The second important way that pest management can address
environmental risk is through the choice of management tactic. If we
associate most risk with the use of pesticides, then the use of
alternative tactics such as host plant resistance, cultural
techniques, or biological control, provide more
environmentally-friendly alternatives. Sometimes we will use such
tactics in combination with pesticides, in which case the use of
alternative tactics may impact frequency of pesticide use. (As an
aside, it's interesting to note that it was exactly this issue of
using biological control in conjunction with pesticides that led to
the development of the EIL and ET by Stern et al.
[1959].)
Although alternative practices are usually regarded as less risky
than pesticides, risk is associated even with these tactics. For
example, an increased chance of soil erosion is associated with
certain rotational patterns or tillage practices. Similarly, very
high levels of an antibiotic factor in a crop can, of themselves,
prove to be of risk. (One example of this was the development of a
potato cultivar with strong insect resistance but such high levels of
alkaloid in the tubers that it was unsafe for human consumption.)
Even with biological control, there have been recent arguments about
assessing risk to native species from natural enemy introductions
(for perspectives, see Caruthers and Onsager [1993], Lockwood
[1993a,b]). One problem with the use of alternative tactics
is that most of these tactics have to be used in a preventive
fashion. One of the outstanding limitations in pest management,
particularly relative to finding alternative practices, is that we
have few alternatives to pesticides for therapeutic management
actions.
One development that does relate to the choice of management
tactic for improving environmental quality has been changes in
pesticide development over the past thirty years. Since the discovery
of the deleterious environmental impacts of DDT and other chlorinated
hydrocarbons, there has been a very strong effort to find compounds
that not only have good properties with regard to human safety, but
also good properties with regard to environmental safety.
Environmental safety includes such considerations as effect on
non-target species (birds, mammals, fish, etc.) and reduced potential
for long-term environmental contamination. In this arena, there have
been remarkable improvements in environmental safety. Development of
the pyrethroids and some of the new, so-called "biorational
compounds" clearly have resulted in chemicals that present much less
environmental risk. Ironically, in developing such compounds a
conflict arises between desirable properties in terms of affecting
pests (such as longevity) versus desirable properties from an
environmental standpoint (such as short life in the environment).
Nevertheless, the gradual transition in insecticide development
toward environmentally safer compounds is a major contribution to
risk reduction.
Environmental Risk and the EIL
Can pest management move beyond frequency of use or developing
safer tactics to more directly address environmental risk? Pedigo and
Higley (1992) have argued that by considering components of the EIL
from an environmental standpoint, it may be possible to identify
approaches that could be pursued in pest management to try to improve
environmental quality. In their original article and a subsequent
paper (Higley and Pedigo 1993), they discuss potential approaches.
Preferential taxation of pesticides based on environmental risk is
one approach they identified, although they note that this would
undoubtedly have the potential to reduce proof of producer
profitability and therefore runs in conflict to other goals of pest
management. Regarding plant response to pest attack, they note that
emphasis on improving the ability of plants to tolerate or compensate
for pest injury offers the potential for reducing the need for
intervention and for providing longer-term solutions to pest
management tactics. In reviewing injury per pest, they note that
although this has been proposed with respect to medical pests, there
seems to be little likelihood that it would be of use for agronomic
pests, given that changing the amount of pest attack requires changes
in an entire pest population. However, one example that may be useful
is with respect to weeds, where there are demonstrations that
extremely low concentrations of herbicides can be used to impair the
competitiveness of weed species sufficiently to reduce the need for
subsequent management action (Mortensen and Coble 1997). A final area
they identify has to do with the proportion of the pest population
affected by management action. A number of studies suggest that
current rates of pesticide use are well in excess of what is actually
needed for reliable management, so reduced pesticide rates may be a
simple approach that could considerably reduce pesticide loads,
provided that pesticides are properly applied.
The Environmental EIL
The Pedigo and Higley arguments regarding environmental quality
and the EIL are largely theoretical, in that they have tried to view
the EIL as a framework for identifying areas in pest management where
efforts might be directly focused on questions of environmental
quality. Another, more controversial, approach is to use the EIL
itself to address environmental risk directly. Higley and Wintersteen
(1992) first proposed this approach, which has a relatively simple
premise. Because the EIL relates insect damage to economic costs of
that damage, why not include in the economic costs the indirect
effect of the pest on environmental quality. In other words, in
addition to assigning a cost to crop losses as part of the EIL, why
not also assign an environmental cost, which is a reflection of the
environmental risk posed by the management tactic.
The central difficulty in such a proposal is establishing exactly
what environmental costs would be. As one solution, Higley and
Wintersteen proposed a scheme for developing estimates of the
environmental costs for different pesticides. Once they have these
cost estimates, it is relatively straightforward to reflect costs in
an EIL. The procedure Higley and Wintersteen proposed employs a
technique called contingent valuation, which has been used by
economists to try to put a dollar value on what are called
"non-market goods" (goods whose value is not directly estimable).
Contingent valuation uses opinion surveys to try to estimate costs.
For example, a typical use of a contingent valuation survey might be
to ask how much you would be willing to see your taxes increase to
clean up a polluted lake. Higley and Wintersteen used contingent
valuation to ask field crop producers in the Midwest how much they
would be willing to pay to avoid different levels of environmental
risk. From these cost estimates, they associated a value with
different levels of risk. They went on to define risk by looking at
chemical properties of pesticides and the effect of pesticides on a
variety of non-target species. Additionally, as part of their survey
procedure they also asked field crop producers to define the relative
importance of these different areas of environmental risk.
Spreadsheets
Accompanying this document are examples of data for calculating
environmental risks and formulas for calculating environmental EILs
themselves on computer spreadsheets.
- Spread sheet #1 (view as an HTML
file or as a Microsoft
Excel file): Environmental risk ratings for a variety of
insecticides, based on formulated product - Note that these
rankings differ from those reported in Higley and Wintersteen
(1992), because the Higley and Wintersteen values were for risk
based on active ingredient whereas those in the spreadsheet are
for formulated product.
|
To view spread sheets as Microsoft
Excel files you must have Excel installed as a helper
application in your browser. If you do no have Excel
installed on your computer you can download
a shareware Excel viewer from Microsoft.
Alternatively, save the files to a disk and view using
Excel.
|
Spread sheet #2 (view as an HTML
file or as a Microsoft Excel
file) How environmental EILs can be calculated, and illustration
of the range of values seen in these EILs.
To date, the use of environmental EILs has been theoretical,
although as estimates are refined they will be made available for
pesticide users.
The use of an environmental EIL could potentially reduce frequency
of pesticide use in that a less-safe insecticide would have a much
higher EIL, indicating that it would only be used when pest
populations are larger and therefore more damaging. However, another
important potential use of environmental EILs and/or environmental
cost data is in pesticide selection. Because it's difficult to
differentiate among pesticides based on issues of environmental risk,
an index like the environmental EIL provides one way to compare
pesticides based on something other than efficacy and cost. Improving
procedures to select pesticides based on questions of environmental
risk is an important issue, and there is at least one alternative
procedure to that proposed by Higley and Wintersteen. Kovach et al.
(1992) developed a procedure whereby they rank pesticides based on a
variety of criteria (including features beyond those in Higley and
Wintersteen), so that pesticide users can select pesticides based
upon an environmental risk index.
Some criticisms of both the Higley and Wintersteen (1992) and
Kovach et al. (1992) approaches have been made in the literature.
Higley and Wintersteen (1997) review these critiques in some detail.
Hutchins and Gehring (1993) argue against environmental EILs on
philosophical grounds, based on how environmental risks are assessed
and costs are assigned. Their arguments rest on the premise that
environmental risk is either already considered in the registration
process or is so subjective that it would seriously weaken the value
of objective decision-making tools. Hutchins and Gehring's discomfort
with the subjectivity of environmental risk determinations is common
among scientists and represents an important issue in broadening
perspectives on risks by experts. A good discussion of this
controversy regarding risk perception and subjectivity is provided in
Cothern (1995). Another criticism of the Kovach et al. and Higley and
Wintersteen approaches is that of Dushoff et al. (1994) who argue
that single index methods for evaluating risk are conceptually
flawed. In our opinion, this is really more a question of differences
of philosophy and opinion about how assessments of risk should be
made rather than a legitimate criticism of flawed techniques or other
absolute limitations. Higley and Wintersteen (1997) offer a more
detailed discussion of the Dushoff et al. arguments.
Conclusions
Much emphasis on environmental quality in pest management will
undoubtedly continue to focus on issues of alternative,
environmentally-safe tactics. In particular, developing
non-pesticidal alternatives and more environmentally benign
pesticides will no doubt continue to be emphasized. Nevertheless, we
see a broader need for mechanisms within pest management to address
issues of environmental safety. In this effort, a variety of
approaches are likely to have merit. In particular, looking at
aspects of pest management and identifying ways we might change
practices to improve environmental safety, as well as developing new
tools such as pesticide selection criteria and environmental EILs,
are among the most immediate approaches that can be used in this
enterprise. Given the many difficulties in implementing IPM programs,
many barriers to implementing new techniques (like the environmental
EIL or the Kovach et al. index) clearly exist. Nevertheless, because
our pest management programs must be responsive to the needs of the
general public as well as to individual growers, developing
procedures to improve environmental safety in pest management will
remain a priority for the foreseeable future.
Disclaimer: "The thoughts, beliefs, and proposals
presented do not necessarily represent the consensus opinion of
DowElanco or the Agricultural Products Industry."
References
Carruthers, R. I., and J. A. Onsager. 1993. Perspective on the use
of exotic natural enemies for biological control of pest grasshoppers
(Orthoptera: Acrididae). Environ. Entomol. 22:885-903.
Cothern, C. R., ed. 1995. Handbook for Environmental Risk Decision
Making: Values, Perceptions, and Ethics. Lewis Publishers, Boca
Raton, FL.
Dushoff, J., B. Caldwell, and C. L. Mohler. 1994. Evaluating the
environmental effect of pesticides: a critique of the environmental
impact quotient. Am. Entomol. 40:180-184.
Hart, R.W. & A. Turturro. 1987. Educating the public
concerning risks associated with toxic substances. In N.N. Ragsdale
and R.J. Kuhr [eds.], Pesticides: Minimizing the Risks.
American Chemical Society, Washington, D.C.
Higley, L. G., and W. K. Wintersteen. 1992. A novel approach to
environmental risk assessment of pesticides as a basis for
incorporating environmental costs into economic injury levels. Am.
Entomol. 38:34-39.
Higley, L.G., M.R. Zeiss, W.K. Wintersteen & L.P. Pedigo.
1992. National pesticide policy: a call for action. Am. Entomol.
38:34-39.
Higley, L. G., and L. P. Pedigo. 1993. Economic injury level
concepts and their use in sustaining environmental quality. Agric.
Ecosystems Environ. 46:233-243.
Higley, L. G., and W. K. Wintersteen. 1997. Thresholds and
environmental quality. in L. G. Higley and L. P. Pedigo, (eds.)
Economic Thresholds for Integrated Pest Management. Univ. of Nebraska
Press, Lincoln, NE. in press
Hutchins, S. H., and P. J. Gehring. 1993. Perspective on the
value, regulation, and objective utilization of pest control
technology. Am. Entomol. 39:12-15.
Kovach, J. C. Petzold, J. Degni, and J. Tette. 1992. A method to
measure the environmental impact of pesticides. New York's Food and
Life Sciences Bull., Cornell Univ., Ithaca, NY Number 139.
Kraus, N., T. Malmfors & P. Slovic. 1992. Intuitive
toxicology: expert and lay judgments of chemical risks. Risk
Analysis. 12:215-232.
Lockwood, J. A. 1993a. Benefits and costs of controlling rangeland
grasshoppers (Orthoptera: Acrididae) with exotic organisms: Search
for a null hypothesis and regulatory compromise. Environ. Entomol.
22:904-914.
Lockwood, J. A. 1993b. Environmental issues involved in biological
control of rangeland grasshoppers (Orthoptera: Acrididae) with exotic
agents. Environ. Entomol. 22:503-518.
Lowrance, W. 1980. The nature of risk. In R.C. Schwing and W.A.
Albers [eds.], Societal Risk Assessment: How Safe is Safe
Enough? Plenum Press, New York.
Mortensen, D. A., and H. D. Coble. 1997. Developing economic
thresholds for weed management. in L. G. Higley and L. P. Pedigo,
(eds.) Economic Thresholds for Integrated Pest Management. Univ. of
Nebraska Press, Lincoln, NE. in press
National Research Council, Committee on Risk Perception and
Communication. 1989. Improving risk communication. National Academy
Press, Washington, D.C. 332 pp.
Pedigo, L. P., and L. G. Higley. 1992. The economic injury level
concept and environmental quality: A new perspective. Am.
Entomologist. 38:12-21.
Pedigo, L. P., S. H. Hutchins, and L. G. Higley. 1986. Economic
injury levels in theory and practice. Annu. Rev. Entomol.
31:341-368.
Peterson, R. K. D., and L. G. Higley. 1993. Communicating
pesticide risks. Am. Entomol. 39:206-211.
Pimentel, D., and H. Lehman. 1993. The Pesticide Question:
Environment, Economics, and Ethics. Chapman and Hall, New York,
NY.
Shrivastava, P. 1987. Bhopal: Anatomy of a Crisis. Balinger
Publishing Company, Cambridge, MA. 184 pp.
Slovic, P., B. Fischhoff & S. Lichtenstein. 1982.
Psychological aspects of risk perception. In D. Sills, C.P. Wolf, and
V.B. Shalanski [eds.], Accident at Three Mile Island..
Westview Press, Boulder, CO.
Slovic, P. 1987. Perception of risk. Science. 236:280-285.
Slovic, P. 1990. The legitimacy of public perceptions of risk. J.
Pest. Ref. 10:13-15.
Stern, V. M., R. F. Smith, R. van den Bosch, and K. S Hagen. 1959.
The integrated control concept. Hilgardia 29:81-101.
Perkins, J. H. 1982. Insects, Experts, and the Insecticide Crisis.
Plenum Press, NY.
Valenti, J.M. 1987. Mass media's effect on public perceptions of
pesticide risk: understanding media and improving science sources. In
N.N. Ragsdale and R.J. Kuhr [eds.], Pesticides: Minimizing
the Risks. American Chemical Society, Washington, D.C.
Wilson, A.R. 1991. Environmental Risk: Identification and
Management. Lewis Publishers, Inc., Chelsea, MI. 413 pp.
Other Suggested Readings
Covello, V.T., P.M. Sandman & P. Slovic. 1988. Risk
Communication, Risk Statistics, and Risk Comparisons: A Manual for
Plant Managers. Chemical Manufacturers Association, Washington,
D.C.
Czerwinski, C. & M.B. Isman. 1986. Urban pest management:
decision-making and social conflict in the control of gypsy moth in
west-coast cities. Am. Entomol. 32(1):36-41.
Fisher, A. 1991. Risk communication challenges. Risk Analysis.
11:173-179.
Morgan, M.G., B. Fischhoff, A. Bostrom, L. Lave & C. Atman.
1992. Communicating risk to the public. Environ. Sci. Technol.
26:2048-2056.
Roth, E., M.G. Morgan, B. Fischhoff, L. Lave & A. Bostrom.
1990. What do we know about making risk comparisons? Risk Analysis.
10:375-387.
Rowan, K.E. 1991. Goals, obstacles, and strategies in risk
communication: a problem-solving approach to improving communication
about risks. J. Appl. Commun. Res. 300-329.
Rowan, K.E. 1994. Why rules for risk communication are not enough:
a problem-solving approach to risk communication. Risk Anal.
14:365-374.
Return to Radcliffe's IPM World Textbook
Home Page.
The University of Minnesota is an equal opportunity educator
and employer.
Last modified: Tuesday, 15 October, 1996
© Regents of the University of Minnesota, 1996
|
