Amer J of Potato Res (2002) 79:183-199
183
Developing a Pesticide Risk A s s e s s m e n t Tool to Monitor Progress in Reducing Reliance on High-Risk Pesticides Charles M. Benbrook 1, Deana L. Sexson 2., Jeffrey A. Wyman 3, Walter R. Stevenson 4, Sarah Lynch 5, John Wallendal 6, Steve Diercks 7, Randy Van Haren s, and Carlos A. Granadino 3 ~BenbrookConsulting Services, 5085 Upper Pack River Road, Sandpoint, ID 83864. 2NPMProgram, Department of Horticulture, 1575Linden Dr., University of Wisconsin-Madison,Madison, WI 53706. 3Department of Entomology, 1605Linden Dr., Universityof Wisconsin-Madison,Madison,W153706. 4Department of Plant Pathology, 1650Linden Dr., Universityof Wisconsin-Madison,Madison, W153706. 5WorldWildlifeFund, 125025~ St., NW, Washington,DC 20037. GWaliendalSupply,Inc., 2401 5~ Ave., Grand Marsh, W153936. ~ColomaFarms, 136 South St., Coloma, W154930. sPest Pros, Inc., Plainfield,WI 54966. *Correspondingauthor. Tel: 608-265-9798;Fax: 608-262-7743;Entail:
[email protected]
ABSTRACT
a g u d a y c r 6 n i c a de cada p l a g u i c i d a p a r a los mamiferos, aves, peces y o r g a n i s m o s acufiticos pequefios, y la com-
A methodology is p r e s e n t e d for the d e v e l o p m e n t of a pesticide risk a s s e s s m e n t tool t h a t was used to m o n i t o r p r o g r e s s i n r e d u c i n g use of high-risk p e s t i c i d e s i n Wisconsin p o t a t o production. M u l t i - a t t r i b u t e toxicity factors a r e c a l c u l a t e d t h a t r e f l e c t each p e s t i c i d e ' s a c u t e a n d chronic toxicity to mammals, birds, fish a n d small aquatic organisms, a n d compatibility with b i o i n t e n s i v e I n t e g r a t e d P e s t M a n a g e m e n t . These factors are t h e n m u l t i p l i e d by the pounds of active ingredient of a given pesticide applied to e s t i m a t e pesticide-specific toxicity units. Wisc o n s i n p o t a t o i n d u s t r y b a s e l i n e toxicity u n i t s by type of
patibflidad con u n b i o i n t e n s i v o Manejo I n t e g r a d o de Plagas. E s t o s factores son inego multiplicados p o r las libras del principio activo del plagnicida aplicado, con el fin de calcular las u n i d a d e s de toxicidad especificas del plagulcida. Se p r e s e n t a el p u n t o de comparaci6n p a r a 1995 de las u n i d a d e s de toxicidad de la i n d u s t r i a de papa de Wisc o n s i n por tipo del plaguicida y p a r a 11 plaguicidas selecc i o n a d o s p o r s e r de m~s a l t o r i e s g o . Se r e p o r t a n l a s reducciones del p u n t o de comparaciSn e n las unidades de toxicidad p a r a 1997 y 1999, como reducciones logradas e n u n e x p e r i m e n t o de campo de escala comercial e n el 2000.
pesticide a n d for 11 t a r g e t e d higher-risk p e s t i c i d e s are p r e s e n t e d for 1995. Reductions in toxicity u n i t s from this
INTRODUCTION
baseline are r e p o r t e d for 1997 and 1999, as are reductions achieved i n a commercial-scale field e x p e r i m e n t i n 2000.
Potatoes are produced in Wisconsin under irrigation on pre~ dominately sandy soils. The Central Sands, a major potato-grow-
RESUMEN
ing region, is characterized by shallow, vulnerable groundwater and high-quality surface waters that support a variety of fish and
Se p r e s e n t a u n a m e t o d o l o g i a p a r a el d e s a r r o l l o de u n a h e r r a m i e n t a de evaluaci6n de riesgos de los plagnicidas que fue u s a d a p a r a vigilar los progresos e n la reducci6n del uso de plaguicidas de alto riesgo e n la producci6n de papas de Wisconsin. Se calculan los a t r i b u t o s mdltiples de los f a c t o r e s de t o x i c i d a d , que r e f l e j a n la t o x i c i d a d
bird species, as well as an active tourist industry (Lynch et al. 2000). Potatoes are grown in rotation with a number of field crops and canning vegetables in intensive, high-yieldproduction systems. Pest pressure is often intense and poses major management challenges with significant regional economic and environmental consequences (Shields et al. 1984; Stevenson et al. 1994). For more than two decades, Wisconsin water-quality-mon-
Accepted for publication December 5, 2001. ADDITIONALKEYWORDS:Toxicity,biointensive IPM, integrated pest management, measurement systems, pesticide risk reduction, pesticide monitoring,pesticide risk assessment.
itoring results have highlighted the need for careful management of nitrogen inputs and soft-incorporated pesticides (FYxen and KeUing 1981; Kelling et al. 1981; Wyman et al. 1985). Groundwa-
184
AMERICAN JOURNAL O F POTATO RESEARCH
ter contamination with the insecticide aldicarb in the early 1980s
Vol. 79
of Agriculture's National Agricultural Statistics Service
threatened the industry's survival and triggered heightened reg-
(USDA/NASS) did not survey potato pesticide use in Wisconsin
ulatory activity (Wyman et al. 1985). It also convinced growers
in 1996. Hence, the "first year" goal applies to changes in pesti-
and industry leaders that more should be done to develop and
cide use from 1995 to 1997. The acute, chronic, and combined
support adoption of"softer" prevention-based IPM systems and
toxicity percentage reduction goals for 1997 were 25%, 15%, and
technologies (Sexson 2001; Stevenson et al. 1994).
20%, respectively. In 1999 third-year goals were 50~ 30~ and
Grower check-off funds have helped support a multidisci-
40% reductions, res~pectively, and the five-year (2001) goal called
plinary team of University of Wisconsin-Madison researchers
for 100% reductions. Recently set goals incorporated in the 2001
addressing potato IPM. The team works closely with growers
ecolabel program are based on incremental reductions in the
and pest management consultants on a range of applied on-farm
toxicity units per acre of fresh market potatoes.
pest management and cropping system research projects. In
In addition to monitoring industry-wide changes in pesti-
close cooperation with the UW potato IPM team, the Wisconsin
cide use and c o r r e s p o n d i n g toxicity units, the i m p a c t s of
Potato and Vegetable Growers Association (WPVGA) estab-
changes in pest management systems on average per acre pesti-
lished a collaborative project with the World Wildlife Fund
cide use and toxicity units have been studied. In response to
(WWF) in 1996. The WPVGA-WWF collaboration set goals for
grower-interest, the team is incorporating the costs of alterna-
reducing use of 11 pesticides and for progress along the IPM
tive pesticides and management systems into the analysis, pro-
continuum toward biointensive IPM (Benbrook et al. 1996). A
ducing estimates of the marginal economic costs of reducing
key goal was to develop methods to monitor and to document
toxicity units through adoption of lower-risk pesticides and IPM
grower adoption of biointensive IPM practices and to explore
system changes.
linkages between IPM adoption and reduced pesticide use. The collaboration formed a multi-stakeholder advisory
BACKGROUND
committee in 1996, and this group has met several times since. Criteria were established to identify "high-risk" pesticides used
Interest is growing worldwide in the potential for IPM to
in Wisconsin p o t a t o production that should be targeted for
reduce the direct and indirect health and environmental costs
reduced use based on acute and chronic mammalian toxicity,
associated with pesticide use. State, federal, and international
ecological risks, and compatibility with biointensive IPM sys-
agencies are funding or participating in programs designed to
tems. A high-risk pesticide active ingredient is one that is signif-
promote IPM adoption (Benbrook et al. 1996). Environmental
icantly more toxic or potentially damaging per unit of exposure
and c o n s u m e r groups are exploring ways to p r o m o t e and
than other registered active ingredients in one or more category
reward IPM adoption through marketplace initiatives (Con-
of risk. Government regulatory agencies and international orga-
sumers Union 2001; Hoppin 1996). The WWF/WPVGA/UW col-
nizations have classified pesticides according to a variety of rel-
laboration is developing standards for potato production and
ative risk measures (e.g., see the International Programme on
pest management in preparation for marketing eco-labeled fresh
Chemical Safety's 1997 LDs0-based acute mammalian toxicity
market potatoes in 2001 (Lynch et al. 2000).
classification systems [IPCS 1996], or the U.S. EPA's system for
Pest managers, researchers, and policy-makers need better
classifying pesticides as "restricted use" based on worker and
tools to monitor the consequences of changes in pest pressure,
environmental risks [Office of Pesticide Programs 2001]).
resistance, and the use of IPM strategies (Ehler and BottreU
Four pesticides used in Wisconsin potato production in
2000). Two traditional measures of pesticide use - - pounds of
1995 met the acute toxicity criterion: methanfidophos, azinphos-
active ingredient applied per acre and number of applications
methyl, carbofuran, and oxamyl. Seven pesticides triggered the
- - are inadequate for estimating the agronomic, environmental,
chronic mammalian toxicity criteria: the fungicides mancozeb,
and public health consequences of pesticide use (Barnard et al.
maneb, chlorothalonil, and triphenyltin hydroxide, the insecti-
1997). A review of several efforts to develop new measurement
cides permethrin and endosulfan, and the herbicide metribuzin.
tools appears in the Consumers Union book Pest Management
Incremental Wisconsin potato industry goals for reducing
at the Crossroads (Benbrook et al. 1996). Levitan (1997) pre-
the toxicity units associated with use of high-risk pesticides
pared a detailed comparative assessment of pesticide impact
were established for 1997, 1999, and 2001. Pesticide use in 1995
measurement systems under development both in the Untied
was used to establish the baseline because the U.S. Department
States and abroad.
2002
BENBROOK, et al.: PESTICIDE RISK ASSESSMENT
185
Improved measurement systems and tools are needed to
assess alternative ways for growers or regulators to achieve a
track trends in IPM system performance and address tradeoffs
given risk-reduction goal. The current reassessment of
as growers adopt more complex, prevention-based IPM systems
organophosphate (OP) insecticide uses and related dietary
reliant largely on reduced-risk pesticides. Many exogenous fac-
exposures, driven by the Food Quality Protection Act (FQPA), is
tors can alter pest pressure and/or pest management efficacy,
a contemporary example.
such as landscape diversity, pesticide resistance, emergence of new, more aggressive strains of pests, new pesticides changes in
MATERIALS AND METHODS
pesticide prices, novel IPM tactics, and resistant cultivars (Benbrook et al. 1996). Potato processors, buyers, and farm lenders also periodically impose contract or loan provisions affecting pest management systems.
Calculating Toxicity Factor Values The equation used in our measurement system to estimate an active ingredient's toxicity factor value contains four com-
Measurement systems need to be dynamic and should
ponent indices: acute mammalian toxicity (AM), chronic mam-
focus, in particular, on documenting impacts of IPM system
malian toxicity (CM), ecological impacts (ECO), and impacts on
changes on the use of higher-risk pesticides over time (Ehler and
beneficial organisms and IPM systems (BioIPM). The latter two
Bottrel12000). Such systems are a structured framework within
components are, in turn, made up of multiple subindices as
which to pose and answer questions about the human health,
explained later in this report.
environmental, ecological, and cost-related impacts of changes
Several issues typically arise in calculating pesticide toxic-
in pest management systems. The components of a pesticide
ity index values focusing on a single risk component, like acute
risk measurement system will vary as a function of cropping sys-
mammalian toxicity. Additional issues arise when combining dif-
tems, soil and climatic conditions, and the dominant risk and
ferent risk indices (e.g., acute and chronic mammalian toxicity
environmental concerns in the geographic region under study.
and avian toxicity) into a multi-attribute measure of relative pes-
There is no inherently "right way" to measure pesticide toxicity
ticide toxicity (Landy 1995).
and risks. Ideally all systems should take into account the vol-
The multi-attribute system used in Wisconsin is evolving. It
nme of pesticides applied, when and how pesticides are applied,
is structured such that larger values imply higher toxicity or risk.
pesticide environmentalfate, when and the extent to which non-
In the case of toxicological measures of dosage such as LD50s
target organisms are exposed, and the toxicity of active ingredi-
(lethal dosage at which 50~ of test animals are ldlled) or EC50s
ents. A variety of factors can influence exposure levels and
(environmental concentration at which 50~ of test organisms
frequency, and hence risk. Our measure, "toxicity tmits," reflects
are ldlled), inverse LD50or EC50values are calculated so that ris-
potential toxic impact per pound of active ingredient applied of
ing index values equate with rising toxicity. In doing so, many
a given pesticide; factors affecting exposures, such as whether a
problems can arise. For some pesticides, acute mammalian tox-
pesticide is applied as a soil-incorporated granular or sprayed
icity tests were carried out years ago, using mostly or exclusively
as a liquid formulation, will determine which organisms are
rats. Results are not directly comparable to current protocols or
adversely affected.
data from mouse tests. In other cases, acute toxicity data are
Several assumptions and subjective judgments are required
available just on formulated products or on active ingredients
in developing a multi-attribute pesticide-risk index. The basic
that differ somewhat from the chemicals in older pesticide for-
purpose of the index will help determine which toxicity, envi-
mulations.
ronmental fate, and risk factors should be taken into account,
Sometimes aquatic invertebrate or fish EC50 values are
to the extent possible, and which can be ignored without under-
reported for tests lasting 24 h and in other cases shorter or
mining the utility of the index in light of a particular application.
longer periods of exposure are used. Sometimes data cover 100~
Consistent logic and transparent decision-rules should govern
pure technical-grade active ingredient, while in others 95% or
the analyst or project team as various decisions are made. Tox-
70~ pure formulations. For some pesticides and test organisms
icity factor values, coupled with data on pesticide use, are par-
the Environmental Protection Agency (EPA) has limited or no
ticularly useful in monitoring changes over time and in
ecotoxicological data in its flies; for others, it has multiple stud-
highlighting possibly high-risk pesticide uses in contrast to those
ies on the same organism, often producing somewhat different
posing modest or no risks to nontarget organisms. Toxicity unit-
results and requiring either a way to choose between several
based measurement systems can also provide a framework to
studies or average results across equally valid studies.
186
AMERICAN JOURNAL OF POTATO RESEARCH
Scaling i s s u e s a r i s e in e s t a b l i s h i n g v a l u e s within an index and when combining results
Vol. 79
TABLE 1--Acute (AM) and chronic mammalian (CM) toxicity index components and values.
across several indices. Scaling is a n e c e s s a r y step to k e e p o n e c o m p o n e n t i n d e x - c h r o n i c m a m malian toxicity (CM), for example - - from dominating multi-attribute toxicity factor values. F o r example, if CM i n d e x values fall within a r a n g e of 10 a n d 1,000, with values for 20 pesticides faliing b e t w e e n 200 a n d 1,000, while all other c o m p o n e n t v a l u e s fall w i t h i n a r a n g e of 1 a n d 100, m u l t i attribute toxicity factors will b e heavily w e i g h t e d t o w a r d chronic m a m m a l i a n risk simply as a n artifact of differences in t h e r a n g e of toxicity values reported a c r o s s risk p a r a m e t e r s a n d pesticides. When t h e r e are large differences in the range a n d variability of values a c r o s s indices, analysts m u s t determine w h e t h e r it is appropriate to allow one or a few categories of risk to d o m i n a t e values while others play tittle or n o role in setting values. Such an o u t c o m e might b e appropriate in a case w h e r e there is evidence t h a t a single risk is b y far the most important, given t h e pesticides u s e d a n d exposure p a t t e r n s within a n agricultural system. In the case of Wisconsin potato production, the multi-stakeholder advisory committee recomm e n d e d t h a t t h e four c o m p o n e n t indices s h o u l d include values in roughly the same range, so t h a t any decisions to alter t h e w e i g h t s a s s i g n e d to a given c o m p o n e n t i n d e x could b e m a d e explicitly through the addition of a weighting factor in t h e multi-attribut~ toxicity-factor equation. Accordingly, c o m p o n e n t i n d e x v a l u e s a n d s u b i n d i c e s were scaled so that individual active ingredient valu e s fell w i t h i n r o u g h l y t h e s a m e r a n g e in e a c h i n d e x a n d s u b i n d e x ; in s o m e cases, s c a l i n g reduced index values, in other cases it raised them. Outlier values in a n i n d e x also require attention to assure that one or a few extremely high valu e s are a n a c c u r a t e a n d r e a l i s t i c r e f l e c t i o n of actual differences in toxicity from use of o n e or a few p e s t i c i d e s c o m p a r e d t o m o s t o t h e r s . A n y m a x i m u m v a l u e in a n i n d e x t h a t is m o r e t h a n t w i c e as l a r g e as t h e n e x t h i g h e s t v a l u e w a s r e v i e w e d as a p o t e n t i a l outlier. In s u c h c a s e s , available and relevant data were reviewed to determine ff the difference in values is c o n s i s t e n t
Chronic LD-50 values Scaled reference dose Chronic (mg/kg) inverse or cPAD Oncogenic toxicity LD-50+ (AM) (mg/kg/day) potency factor (CM) 2,4-D alachlor azinphos-methyl azoxystrobin basic copper sulfate carbofuran chlorothalonil chlorpropham clethodim copper ammonium copper hydroxide copper resinate copper sulfate cyfluthrin cymoxanil diazinon dimethoate dimethomorph diquat disulfoton endosulfan endothal EPTC esfenvalerate ethoprophos fludioxonil fonofos glufosinate ammonium glyphosate imidacloprid linuron malathion maleic hydrazide mancozeb maneb mefenoxam metalaxyl metam sodium methamidophos metiram metolachlor metribuzin oxamyl paraquat dichloride pendimethalin permethrin petroleum oils phorate phosmet piperonyl butoxide propamocarb hydrochloride pymetrozine pyrethrins
375 930 16 5,000 2,500 8 5,000 3,800 1,360 300 1,000 5,000 300 500 960 300 150 3,900 231 3 80 51 1,652 67 26 5,000 8 1,510 4,230 450 4,000 2,100 5,000 5,000 5,000 490 670 285 30 5,000 2,780 2,200 6 283 1,050 500 5,000 2 230 5,000 5,000 5,820 1,500
1.33 0.54 31.25
0.003 0.01 0.0015
100 30 66.67
0.1
0.18
0.56
0.2 62.5 0.1 0.13 O.37 1.67 0.5 0.1 1.67 1 0.52 1.67 3.33 0.13 2.16 192.31 6.25 9.8 0.3 7.46 19.23 0.1 62.5 0.33 0.12 1.11 0.13 0.24 0.1 0.1 0.1 1.02 0.75
0.33 0.005 0.02 0.05 0.01 0.33 0.33 0.33 0.33 0.008 0.013 0.0007 0.0005 0.1 O.O05 0.0001 0.006 0.02 0.0025 0.02 0.0001 0.03 0.002 0.02 2 0.019 0.008 0.024 0.25 0.003 0.005 0.08 0.074
0.3 60 8.85 2 10 0.3 0.3 0.3 0.3 12.5 7.69 142.86 200 1 2O 200 50 5 40 5 200 3.33 50 5 0.05 5.26 12.5 12.5 0.4 130 90 1.25 1.35 109 200 200 1 23.08 100 22.22 3 10.6 0.4 200 9.09 17.14 1 76.92 4.69
0.0077
0.0281
0.06 0.06
1.75
0.01
0.198
16.67 0.1 0.18 0.23 83.33 1.77 0.48 1 0.1 200 2.17 0.1 0.1 0.09 0.33
0.0001 0.0003 0.1 0.013 0.001 0.0045 0.1 0.05 0.25 0.0002 0.011 0.0175 0.1 0.0013 0.064
0.0184
BENBROOK, eta/.: PESTICIDE RISK ASSESSMENT
2002
TABLE1--Continued
187
LD50 from rat assays. LD50values are derived predominantly from the WHO Recommended ClasChronic LD-50values Scaled reference dose Chronic (mg/kg) inverse or cPAD Oncogenic toxicity* LD-50+ (AM) (mg/kg/day)potency factor (CM)
quintozene rimsulfuron sethoxydim spinosad sulfur sulfuric thiamethoxam thiophmlate-methyl trifloxystrobin trifluralin triphenyltin hydroxide
1,700 5,000 3,200 3,738 300 acid 1,563 5,000 5,050 5,000 156
0.29 0.1 0.16 0.13 1.67 1,000 0.32 0.1 0.1 0.1 3.21
0.003 0.818 0.09 0.0268 0.33 0.5 0.013 0.08 0.05 0.024 0
33.33
sification
of Pesticides
by H a z a r d
and
Guidelines to Classification 1996-1997 (International Programme on Chemical Safety 1996). LD50 values for recently registered active ingredi-
0.12
ents are derived from EPA tolerance documents
1.11 3.73 0.3
published in the Federal Register. In a few cases,
0.33
0.3 7.69 1.25 2
Handbook 2000 (Meister 2000), suppliers, or other sources.
0.0077 2.8
14.43
values, and AM index values for pesticides used
200
in Wisconsin potato production. A scaling factor
Notes: + "Scaled inverse LD50is (500/LD50)
LD50 values were derived from Farm Chemicals
Table 1 reports LD50 values, inverse LD50
of 500 was used in calculating acute mammalian (AM) values. For example, the LD50of the organophosphate insecticide azinphos-methyl is 16
with other differences observed in comparable toxicology stud-
mg/kg, so the scaled inverse acute mammalian toxicity index
ies carried out on closely associated organisms, or instead
value is 31.25 (500/16). The most acutely toxic pesticide used in
reflects how one particular study was carried out or how the
Wisconsin potato production is phorate, which has an LD50 of
results of certain studies were interpreted.
2 mg/kg and a scaled inverse LDs0 value of 250 (capped in
In adjusting outlier values, guidance was sought from the
Table 1 at the maximum allowed value, 200). The least acutely
project advisory committee and experts in the relevant disci-
toxic pesticides have LD50 values of 5,000 mg/kg or higher
plines. As shown in the Table 1, maximum values were set at 200
(5,000 mg/kg is typically the highest dose tested). When scaled,
in one case in the acute mammalian (AM) index (phorate), and
AM values are 0.1 for these active ingredients (e.g., chloro-
in six cases in the chronic mammalian index (CM). One scaled
thalonil, the EBDCs, and strobilurin fungicides). The table
fish subindex value was set at 200 (esfenvalerate, Table 2), and
shows that acute mammalian toxicity contributes little to the
overall 2001 Ecotox index values were truncated at 200 in two
total toxicity factor values for many widely used pesticides.
cases (esfenvalerate and cyfluthrin). The esfenvalerate BioIPM
AM values for 28 active ingredients are below 1. Only two
index was also set at 200 (Table 3).
organophosphate insecticides - phorate and disulfoton - have
Data gaps are pervasive when calculating pesticide toxic-
values over 100.
ity index values. For example, even basic mammalian toxicity
The chronic mammalian (CM) toxicity index measures
data are lacking for most biopesticides (active ingredients that
risks stemming from longer-term, low-level drinking water,
work through a nontoxic mode of action [e.g., an insect growth
occupational, and dietary exposures (Benbrook et al. 1996). It
regulator] and/or that are naturally derived biochemicals [e.g.,
encompasses the capacity of an active ingredient to cause
Bacillus thuringiensis (Berliner)]) and for copper-based fungi-
adverse health impacts such as cancer or impaired immune sys-
cides, since the EPA has exempted pesticides containing these
tem fimction and is driven largely by EPA population-adjusted
ingredients from testing and tolerance requirements (set forth
chronic Reference Doses, otherwise referred to as "cPADs"
in Code of Federal Regulations, section 180.1001). Fish toxicity
(chronic Population Adjusted Doses are chronic Reference
data for fungicides are limited and relatively few herbicides have
Doses modified by any FQPA-driven added safety factors)
been tested for impacts on beneficial arthropods. Default values
(Office of Pesticide Programs 2000).
have been established in such cases, as discussed in each of the following sections.
The index is a composite variable developed and first calculated to evaluate long-ten~a trends in the chronic toxicity of pesticides as part of the analysis reported in the Consumers
Component Indices The acute mammalian (AM) toxicity index is based on oral
Union book Pest Management at the Crossroads (Benbrook et a/. 1996). The CM index formula is
188
AMERICAN JOURNAL OF POTATO RESEARCH
Vol. 79
TABLE 2--Eco Toxicity factor values from 199 7 to 2001 and percentage change from 2000 to 2001. 2001 component indices (scaled) Active ingredient triphenyltin hydroxide azoxystrobin txifloxystrobin chlorothalonil quintozene (PCNB) dimethomorph basic copper sulfate maneb fludioxonil copper sulfate mefenoxam*** metalaxyl copper hydroxide mancozeb copper resinate copper ammonium cymoxanil metiram propamocarb hydroclfioride thiophanate-methyl sulfur ....... trffiumlin diquat EPTC pendimethalin endothal metribuzin linuron paraquat dichloride 2,4-D chlorpropham rimsulfuron metolachlor clethodim glufosinate ammonium glyphosate Alachlor setho x y ~ . . . . cyfluth~ esfenvalerate phomte carbofuran endosulfan diazinon permethrin oxamyl disulfoton azinphos-methyl fonofos phosmet methamidophos dimethoate ethoprophos pyrethrins pyn~etrozine thiamethoxam imidacloprid spinosad malathion piperonyl butoxide
Bacillus thuringieusis metam sodium maleic hydrazide sulfuric acid
AI type Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fmlgicide Fungicide Fungicide ~cide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Other Other Other
Daphnia (col. C)
.....
25.00 1.00 1.00 3.57 14.80 1.00 0.25 0.07 0.23 0.30 0.00 0.00 0.25 0.25 0.25 0.25 0.01 0.04 0.00 0.01 0.00 0.42 0.04 0.63 0.89 0.00 0.06 1.25 0.21 0.05 0.07 0.00 0.01 0.01 0.00 0.00 0.01 0.00 177.30 166.67 0.68 0.74 0.15 2.60 13.30 0.01 0.36 0.01 12.50 0.00 0.74 10.00 0.37 2.16 3.00 0.00 0.00 0.00 0.10 0.02 0.00 0.11 O.00 0.00
Fish (col. D) 52.60 5.60 5.60 22.70 0.33 10.00 1.47 7.08 5.03 0.90 0.02 0.02 0.92 1.57 0.12 0.12 0.12 0.01 0,00 0.08 0.01 171.50 0.01 0.08 4.98 0.04 0.02 0.30 0.11 0.32 0.31 0.00 0.25 0.06 0.02 0.01 0.25 ....... 0.01 156.86 200.00 86.46 1.30 115.08 0.71 28.16 0.03 0.00 16.69 5.81 0.00 0.00 0.03 0.11 8.86 4.00 0.50 0.00 0.45 0.10 0.04 ...... 0.08 2.47 0.02 0.01
Avian (col E) 40.61 1.29 1.29 1.55 1,17 1.44 6.37 0.87 1.44 6.40 3.37 3.37 1.37 0.42 1.43 1.40 1.28 1.20 0.93 0.62 ........... 0.01 1.22 16.84 11.85 5.00 10.27 7.14 4.61 3.39 2.26 1.55 1.87 1.24 1.29 1.29 1.29 0.91 .... 0.62 0.06 0.23 88.24 140.58 3.15 50.85 0.01 38.46 37.04 13.13 7.77 24.19 17.62 5.19 12.46 0.03 0.14 3.56 3.56 0.11 0.22 0.11 0.06 5.17 1.38 0,01
2001 index
1998EcoTox Percent change
[col C+D+E]
index
to 2001
118.20 7.89 7.8994 27.82 16.30 12.44 8.09 8.02 6.70 7.60 3.39 3.39 2.54 2,24 1.80 1.77 1.41 1.25 0.94 0.71 __0_._02 173.14 16.89 11.96 10.87 10.31 7,22 6.16 3.71 2.63 1.93 1.87 1.50 1.36 1.31 1.31 1.17 0:63 200.00 200.00 175.37 142.62 118.38 54.16 41.47 38.50 37.40 29.84 26.09 24.20 18.36 15.22 12.94 11.05 7.14 3.56 3.56 0.56 0.42 0.18 0=_14 7. 74 1.40 0.02
118.20 41.29
0.00 .0.81
27.82
0.00
12.44 8.09 8.02
0.00 0.00 0.00
2.50
2.04
3.39 2.54 2.24 1.80 1.77 1.41 1.25 0.94
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.50
0.02 .......
0.00
16.89
0.00
10.87 10.31 7.22 6.16 3.71 2.63
0.00 0.00 0.00 0.00 0.00 0.00
1.87 1.50
0.00 0.00
1.31 1.17 0.63 ......
0.00 0.00 0.00
200.00 180.56 144.90 118.38
0.00 -0.93 -0.02 0.00
41.47 38.50 36.35 29.84 28.80 24.20 18.36 15.22 12.95 11.05
0.50 0.00 0.03 0.00 -0.09 0.00 0.00 0.00 0.00 0.00
3.56
0.00
0.42 0.18 0.14 7. 74 1.40 0.02
0.00 0.00 0.00 0.00 0.00 0.00
2002
BENBROOK,
eta/.:
PESTICIDE RISK ASSESSMENT
189
TABLE 3--BioIPM factor values for 2001, changes since 1997, and percentage change from 2000 to 2001.
Active ingredient
AI type
mefenoxam metalaxyl sulfur mancozeb triphenyltin hydroxide maneb azoxystrobin trifloxystrobin metiram propamocarb hydrochloride chlorothalonil cymoxanil quintozene (PCNB) copper hydroxide copper resinate copper ammonium fludioxonil dimethomorph thiophanate-methyl basic copper sulfate copper su!fate rimsulfuron pendimethalin metribuzin paraquat dichloride sethoxydim linuron alachlor glyphosate glufosinate ammonium endothal diquat chlorpropham metolachlor tnfluralin 2,4-D EPTC clethodim esfenvalerate cyfluthrin permethrm disulfoton azinphos-methyI pyrethrins spmosad oxamyl imidacloprid thiamethoxam dimethoate carbofuran malathion diazinon phorate methamidophos endosulfan ethoprophos phosmet fonofos piperonyl butoxide pymetrozine bt metam soditm~ maleic hydrazide sulflndc acid
Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Other Other Other
2001 component indices
2001 BioIPM
Resistance (col. C)
Beneficials (col. D)
Bee toxicity (col, E)
[(C+D+E) x0,5]
1997 BioIPM
1998 BioIPM Index
2000 BioIPM
Percent 2000to 2001
100 100 6 10 18 10 40 40 10 30 10 14 15 5 5 5 15 14 20 5 5 100 100 60 6 45 6 6 6 6 6 6 10 9 6 6 6 6 192 168 168 54 48 108 50 45 72 72 36 45 40 48 24 48 68 45 45 23 9 30 8 6 6 6
50 50 80 60 70 60 10 10 60 30 50 30 30 40 40 40 20 20 20 10 10 51 17 51 65 15 51 41 41 41 40 40 30 17 20 17 15 15 67 100 103 67 70 150 15 139 40 40 71 71 100 70 100 77 61 67 33 56 40 10 5 60 40 20
0.1 0.1 0.0 0.6 0.1 0.8 0.1 0.1 0.6 1.0 0.1 0.4 0.1 1.0 1.0 1.0 0.0 0.1 0.1 1.0 1.0 0.1 0.2 0.6 0.2 1.0 0.6 0.6 0.1 0.1 1.0 0.6 0.6 0.1 0.1 0.1 0.6 0.1 166.7 100.0 90.9 166.7 166.7 76.9 100.0 32.3 87.5 87.5 83.3 62.5 37.0 45.5 37.0 11.6 1.4 2.4 16.4 3.0 0.6 5.0 0.6 0.3 0.6 1.0
75 75 43 35 44 35 25 25 35 31 30 22 23 23 23 23 18 17 20 8 8 86 69 56 36 31 29 24 24 24 24 23 20 13 13 12 11 11 200 184 181 144 143 142 83 108 1O0 100 95 89 89 82 81 68 63 57 47 41 25 23 7 33 23 14
113.0 113.0 45.2 41.5 38.4 44.1
113.0 113.0 45.2 43.5 43.2 42.9 34.8
113.0 113.0 45.2 43.5 43.2 42.9 34.8
-33.6% -33.6% 4.9% -18.7% 1.9~ -17.4% -28.0%
32.7 32.4 30.4 34.2
33.0 32.4 30.0 27.8
33.0 32.4 30.0 27.8
7.1% -5.9% 0.0% -20.0~
30.1 30.1 30.0
29.7 29.7 29.6
29.7 29.7 29.6
-22.6% -22.6% -22.3%
21.6
21.6
-21.2%
51.0
22.8 22.8 96.4 78.9 64.7 52.5 48.4 39.1 51.2 51.0
22.8 22.8 96.4 78.9 64.7 52.5 48.4 39.1 51.2 51.0
~4.9% -64.9% -11.3% -13.0O/5 -13.7% -32.2~ -37.0~ -26.2% -53.2% -53.5%
26.8 30.4
26.8 26.7
30.4
30.4
26.8 26.7 24.3 30.4
-12.3% -12.5% -16.2% -57.1%
41.2
41.2
-72.0~
126.7
182.1
141.2 79.0 109,4
156.8 138.9 130,0 126.0
94.0 163.6
106.5 200.0
182.1 159.2 156.8 133.9 130,0 126.0 112.0 106.5 99.8
9.8% 15.6% 15.4% 3,4% 9.6% 13,1% -26.3% 1.5 4).1%
81.3 112.0
60.8 28.0
92.3 111.4 82.8 O.0 96.4 74.6 66.3 77.6 49.9 64.4 27,9
58.5 26.5 18.8
58.5 26.7 18.8
92.3 111.4 82.8 81.6 96.4 74.6 66.3 77.6 49.9 64.4 27.9 26.0 7.5 58.5 26.7 18.8
3.3~ -19.9% 6.0% 0.5% -16.5% ~8.5% -5.2~ -26.5% -5.1% -37.1% -10.0% -13.5% 4.5% 43.4% -12.5% -28.2%
23.2 53.1 96.4 64.5 38.1 38.8 38.8
85.1 62.1 71.2 65.6
190
AMERICAN JOURNAL OF POTATO RESEARCH
CM for Pesticidex = [(0.1/cRfDx) x EDx] + [Q*x x 50 x CLASSx]
Vol. 79
ration's original 1995 list of five endocrine disruptors was derived from Colborn et al. (1993) and has twice been updated on the basis of new information. A review of the estrogenic
Where: cRfD = EPA chronic Reference Dose or chronic Population Adjusted Dose (or a default value or provisional estimate) ED = Endocrine d i s r u p t o r - - ff yes, value=3; if no information or no evidence from appropriate assays, value=l Q* = EPA oncogenic potency factor (slope of the doseresponse curve) CLASS = EPA Oncogenicity Classification. If Class A or B2, value=10; if C, value=5; if D, value=2.
potential of four synthetic pyrethroids supported inclusion of esfenvalerate and permethrin on the list (Go et al. 1999). Pesticide impacts on neural development can also be endocrine related and support the placement of several organophosphate and carbamate insecticides on the list (Bigbee et al. 1999; Repetto and Baliga 1996). Colborn et al. (1999) suppo~s the collaboration's current list of endocrine disruptors, as well as the possible need to add a few additional active ingredients to the list in future updates. In setting cRfDs/cPADs, the EPA assesses evidence of heightened toxicity to pregnant and/or young animals (Kimmel
Table I reports CM values by active ingredient, chronic Ref-
1995). The most common tests where such effects are seen
erence Doses (cRfD) or cPADs, and oncogenic potency factors
include two-generation reproduction studies and developmen-
for those active ingredients deemed carcinogenic by EPA.
tal neurotoxicity studies. In such cases, EPA often adds a three-
Chronic RfDs/cPADs are derived from Federal Register notices
to ten-fold added safety factor to account for endocrine-related
(pesticide Federal Register notices are accessible at http://www.
risks and other heightened risks faced by vulnerable populations
epa.gov/fedrgstr/EPA-PEST/indey~html) and are current through
(Office of Pesticide Programs 1999). The ten-fold provision in
July 2000. Oncogenic potency factors are from EPA's periodic
the 1996 Food Quality Protection Act (FQPA) codified EPA's
summary of data on pesticides shown to cause cancer (Burnam
existing practice of adding an additional ten-fold safety factor in
1999) or recent Federal Register documents reporting revised
stetting the RfDs of chemicals that are more toxic to young or
risk assessments.
pregnant animals or for chemicals with significant data gaps.
Pesticides known to be e n d o c ~ e disruptors are treated dif-
Prior to passage of the FQPA, EPA had imposed a three-fold
ferently in calculating CM values in that the cRfD/cPAD portion
added factor in 21 cases, a ten-fold added factor in 22, and
of the above CM formula includes an added three-fold safety fac-
greater than ten-fold in six cases involving widely used pesti-
tor for such pesticides. An EPA-sponsored symposium in 1995
cides (Office of Pesticide Programs 1995). In the majority of
adopted the following consensus definition of endocrine dis-
these cases, the added safety factors were imposed because of
ruptor:
poorly designed studies, a lack of a "No Observed Effect Level,"
An exogenous agent that interferes with the production, release, transport, metabolism, binding, action, or elimination of natural hormones in the body responsible for the maintenance of homeostasis and the regulation of developmental processes (Kavlock et al. 1996:716).
or a major data gap (see Groth et al. [2001] for details on preFQPA and FQPA safety factors [Table 2.2] and why safety factors have been imposed on organophosphate insecticides [Appendix 1]). When the FQPA is fully implemented, pesticide cRIDs/cPADs will presumably reflect heightened risk faced by pregnant or young animals, including endocrine effects. This process will
The WWF/WPVGA/UW collaboration relies on the WWF's
take at least another five to seven years, given the time needed
Wildlife and Contaminants Program (WWF-WCP) staff, and their
for EPA to develop new endocrine disruptor test protocols and
extepsive endocrine disruptor research database, to identify pes-
for industry to generate new data, followed by EPA evaluation of
ticides that are endocrine disruptors. A member of the WWF-
the new data. In the interim, the collaboration advisory commit-
WCP team, Dr. Francoise Brucker-Davis has published a
tee felt it appropriate to include a three-fold safety factor reflect-
thorough review on endocrine-related thyroid effects (Brucker-
ing potential endocrine effects. While this safety factor is less
Davis 1998). This review discussed evidence of thyroid effects
than the ten-fold factor called for by the FQPA, in many cases
covering nine of the 12 pesticides now identified by the collabo-
EPA has already added an additional safety factor for reasons
ration as known or suspect endocrine disruptors. The collabo-
that overlap to some degree with endocrine-related concerns.
2002
BENBROOK, eta/.: PESTICIDE RISK ASSESSMENT
191
The ecological (ECO) toxicity index is the sum of avian,
and fungicides, e.g., the Daphnia scaling factor for insecticides
aquatic and small invertebrate subindex values and is shown in
was 0.025 and for herbicides and fungicides, 0.25. Even with the
Table 2. Avian toxicity values were provided by Dr. Pierre
lower insecticide-scaling factor, five of 23 insecticides have
Mineau, Canadian Fish and Wildlife Service. While there are
Daphnia values greater than 10, while the highest herbicide
more than 10,000 bird species in the world, pesticides are gen-
value is just 1.25 and 18 of 21 fungicides have a value of one or
erally tested in just one to three species for acute toxicity
lower. The trout-scaling factor was 0.1 for insecticides and 1.0
(Mineau et al. 2001). With an international team, Mineau devel-
for other pesticides. The bluegill values were 0.25 and 2.5 for
oped an avian toxicity model, drawing on a database with more
insecticides and other pesticides, respectively. The esfenvaler-
than 2,300 acceptable LD50values for 872 pesticides (Mineau et
ate fish value was capped at 200 and the overall Ecotox index
al. 2001). These LD50 studies were used to estimate dosage lev-
(the sum of the Daphnia, fish and avian subindex values) was
els expected to protect 95% of the bird species within an ecosys-
capped at 200 in the case of cyfluthrin and esfenvalerate.
tem. The resulting values are a robust index of relative avian
Better data are needed on secondary and tertiary ecosys-
toxicity following acute exposures. Work is underway to expand
tem impacts of pesticides to estimate ecotoxicity values more
the model to encompass sub-acute and reproductive effects. As
accurately. Developing study protocols and supporting needed
in the case with other parameters, updated values will be incor-
research warrant more attention by regulators, federal research
porated in our estimates of avian toxicity when available.
agencies, and the pesticide industry. Priority research topics
Impacts of pesticides on small aquatic organisms are esti-
should include decreased abundance and diversity of inverte-
mated based on data on water fleas, Daphnia magna (Straus),
brates; impairment of long-term reproductive success; and
the most frequently listed crustacean species in the EPA-Eco-
reduction in the number of plants that serve as hosts for inver-
toxicology database (Montague 1999). Comparable studies were
tebrates or as critical elements in the food chain.
selected from the EPA database in terms of the most common
The biointensive Integrated Pest Management (BioIPM)
concentration of the material tested in a given species (typically
index encompasses impacts of pesticides on the ability of farm-
at least 90% concentration and usually 100% technical material),
ers to progress along the IPM continuum toward more biologi-
as well as the length of exposure (usually 48 h). Average values
caliy and prevention-based IPM systems such as those described
were calculated when more than one study was available.
by Lewis et al. (1997). The components of the BioIPM index
Data on pesticide impacts on several fish species are avail-
include resistance management, impacts on beneficial non-tar-
able from studies in EPA files, much of it from a comprehensive
get organisms, and bee toxicity. With the exception of bee toxi-
report by Mayer and Ellersieck (1986). Rainbow trout,
city, data needed to calculate the other two BioIPM subindices
Oncorhynchus mykiss (Walbaum) and bluegill, Lepomis macrochirus (Rafinesque), are the two most widely used test
are incomplete. A team of Wisconsin potato growers, pest man-
species and are common in Wisconsin surface waters. Compa-
develop preliminary estimates based on collective knowledge
rable studies were selected by active ingredient involving the
and experience. Values in Table 3 reflect pesticide use patterns,
most frequently tested concentration. When there were two or
soils, and cropping systems in central Wisconsin and are not
more studies, LC50values in trout and bluegill studies were aver-
necessarily appropriate for other potato-growing regions. The
aged.
team developed an estimate of each pesticide's likelihood of trig-
To produce Daphnia, trout, and bluegill subindices, LC50
agement experts, and university faculty was c o n v e n e d to
gering resistance in target pests (third column, Table 3). For
values were inverted, so that the higher the subindex value, the
insecticides, values were computed from estimates of the ability
more toxic the pesticide in a given assay. The resulting inverted
of insects to adapt to each insecticide's mode of action (value
values vary over as many as seven orders of magnitude, with val-
of 1, "less likely" to 3, "prone to develop resistance"), the active
ues for insecticides routinely much higher than for herbicides
ingredient's spectrum of activity (scale 1 to 10, few species
and fungicides. For example and as expected, the average insec-
impacted to many species), and foliar half-life values. The
ticide Daphnia subindex value is more than 50 times greater
pyrethroid, esfenvalerate had the highest score of 192. For fungi-
than the average fungicide value.
cides, values were computed taking into account leaf-haft lives
Different scaling factors were applied to narrow the wide
and an estimate of the ability of pathogens to adapt to each
range across subindex values shown in Table 2. A ten-fold lower
fungicide's mode of action. A scale of I to 5 was used, with 1
scaling factor was used for insecticides in contrast to herbicides
assigned to active ingredients with a "remote" chance of leading
192
AMERICAN JOURNAL OF POTATO RESEARCH
Vol. 79
to resistance and 5 assigned to those "likely" to lead to resistant
bee toxicity value for spinosad was set at 100, a mid-range value
phenotypes.
based on conflicting data on bee toxicity levels (Heneghan 1998;
Metalaxyl, mefenoxam, rimsulfuron, and
pendimethalin have the highest subindex value of 100; the use of
Montague 2001).
each active ingredient has led to documented cases of resistance
BioIPM index values are calculated by summing the values
(Brent 1995; Brent and Hollomon 1998; IRAC 2001; FRAC 1999;
of the three subindices as reported in Table 3, and then multi-
Weed Science Society of America 2001).
plying the result by 0.5, a scaling factor used in order to bring
Another subindex estimates insecticide impacts on benefi-
most values under 200. In general and as expected, insecticide
cial arthropods and was derived from the "Toxic Effect" index
BioIPM values are on average substantially higher than herbi-
developed at Oregon State University (Theiling and Croft 1988)
cide and fungicide values.
using the formula:
Some recently registered pesticides classified by EPA as
"Impact on Beneficials Pesticidex" = 100/(5-Toxic Effect
"reduced risk" active ingredients score relatively high in the
Pesticidex) Toxic Effect values were not available for most her-
BioIPM index. These scores reflect the potential for newer, often
bicides and ftmgicides. Values in column four, Table 3 for these
more selective pesticides to select for resistance, as well as
other classes of pesticides are derived predominantly from the
sometimes-significantimpacts on non-target organisms, partic-
Kovach et al. (1992) "EnvironmentalImpact Quotient." The team
ularly bees. The project advisory committee decided that values
of experts in Wisconsin projected values not otherwise avail-
for resistance and/or bee toxicity should be adjusted in cases
able, drawing on field experience.
where clear label directions preclude use of a pesticide in a way
Many species of soil microorganisms play important roles
that gives rise to resistance or significant bee exposure. For
in enhancing nitrogen retention and availability, promoting
example, the azoxystrobin and spinosad labels c o n t a i n an
healthy root development, and suppressing nematodes and
explicit resistance management practice (rotation with another
related plant pathogens. Further work is needed to develop a
product that works through an alternative mode of action).
BioIPM subindex that captures pesticide impacts on soil
Ongoing work is needed to review other new and revised pesti-
microorganisms. Development of such a subindex remains a col-
cide product labels that may also contain use pattern restrictions
laboration priority.
that markedly lesson the risk of impacts on bees or beneficials,
Pesticide toxicity to bees is among the most significant eco-
or the risk of selecting resistant pest biotypes.
nomic losses associated with pesticide use, especially where
Final multi-attribute toxicity factors are calculated from the
fruit and vegetable yields depend on pollination. Bee toxicity
four component indices: AM, CM, ECO, and BioIPM and are
data was obtained from Dr. Pieter Oomen, a scientist working
reported in Table 4. The equation used to calculate the Wiscon-
for the Dutch Ministry of Agriculture. The Oomen dataset is con-
sin collaboration's multi-attribute index is
sidered one of the most authoritative in the world and includes data on both Contact and oral routes of exposures (Heneghan 1998). In a few cases, values were also extrapolated from the acute bee toxicity ratings in Farm Chemicals Handbook '99 and Farm Chemicals Handbook 2000 (Meister 1999, 2000).
Multi-attribute Toxicity Factorx = (0.5)*AMx + CMx + ECOx + (1.5)*BioIPM x The collaboration's advisory committee applied a (0.5) weight to the acute mammalian toxicity component because of
The bee toxicity value for imidacloprid required adjustment
the relative lack of circumstances leading to acute worker and
because of the large difference in bee toxicity as a function of
applicator exposure in Wisconsin potato-production systems. In
formulation and when and how this pesticide is applied. If
addition, U.S. Department of Agriculture pesticide residue data
applied as a liquid foliar spray, imidacloprid's bee toxicity value
were reviewed and show low frequency and levels of residues of
would be the highest of any pesticide used in Wisconsin potato
acutely toxic pesticides in potatoes, especially after washing,
production. But applied as a soil insecticide at or soon after
peeling, cooldng and/or processing (Agricultural Marketing Ser-
planting, there is little risk of exposure to bees. The at or near
vice 1996). A weight of (1.5) was placed on the BioIPM compo-
planting use pattern accounts for more than 75 % of imidaclo-
nent index in light of the importance of pesticide compatibility
prid~)ounds of active ingredient applied and results in a bee tox-
with biointensive IPM as Wisconsin growers strive to adopt
icity rating of 50 (National Agricultural Statistics Service 2000).
more sophisticated, prevention-based IPM systems.
A weighted average imidacloprid bee impact value of 87.5 was
BioIPM values account, on average, for about 65% of multi-
calculated using the formula [0.75(50) +0.25(200)]. The scaled
attribute factor values across the pesticides used in Wisconsin
2002
BENBROOK, eta/.: PESTICIDE RISK ASSESSMENT
193
TABLEC--Multi-attribute toxicity factor values for 2001. 2001 Four Component Indices
Pesticide
A~I Type
triphenyltin hydroxide metiram mancozeb maneb metalaxyl mefenoxam quintozene (PCNB) chlorothalonil sulfur triflox-ystrobin propamocarb hydrochloride azoxystrobin cymoxanil dimethomorph fludioxonil copper hydroxide copper ammonium copper resinate thiophanate-methyl copper sulfate basic copper sulfate trilluralin 2,4-I) rimsulfuron metribuzin pendimethalm paraquat dichloride diquat EPTC alachlor linuron endothal sethoxydim giufosinate ammonium giyphosate chlorpropham clethodim metolachlor phorate disulfoton esfenvalerate cyfluthrin carbofuran dimethoate oxamyl methamidophos azinphos-methyl permethrin diazinon ethoprophos endosulfan pyrethrins fonofos thiamethoxam imidacloprid malathion spinosad pymetrozine phosmet piperonyl butoxide
Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Fungicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Herbicide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide hlsecticide Insecticide Insecticide Insecticide Insecticide Insecticide Insecticide Other Other Other
Bacillus thuringiensis metam sodium maleic hydrazide sulfuric acid
Acute toxicity
Bio IPM
3.2 O.1 0.1 0.1 0.7 0.1 0.3 O.1 1.7 0.1 0.1 O.1 0.5 O.1 0.1 0.5 1.7 0.1 0.1 1.7 0.2 O.1 1.3 O.1 0.2 0.5 1.8 2.2 0.3 0.5 O.1 9.8 0.2 0.3 0.1 0.1 0.4 0.2 200 192 7 1 63 3 83 17 31 1 2 19 6 0 63 0 1 0 O 0 2 0 0 2 0 1
44 35 35 35 75 75 23 30 43 25 31 25 22 17 18 23 23 23 20 8 8 13 12 76 56 59 36 23 11 24 29 24 31 24 24 20 11 13 81 144 200 184 89 95 108 68 143 181 82 57 63 142 41 100 100 89 83 23 47 25 7 33 23 14
Chronic Acute Index EcoTOX BioIPM Index Index (.5 x Acute Tox) Index (1.5 x BioIPM) (col.F) (col. G) (col. H) (col. e) 200 200 130 90 1.4 1.3 33.3 8.9 0.3 2.0 1.0 0.6 7.7 1.0 3.3 0.3 0.3 0.3 1.3 0.3 0.3 14.4 100 0.1 23.1 3.0 22.2 20.0 40.0 30.0 12.5 5.0 1.1 5.0 0.1 2.0 10.0 1.0 200 200 5 13 60 200 100 200 67 11 143 200 50 5 50 8 5 13 4 77 9 17 0 109 0 0
1.6 0.1 0.1 0.1 0.4 0.0 O.1 0.1 0.8 0.0 0.1 0.1 0.3 0.1 O.l 0.3 0.8 0.1 0.1 0.8 0.1 0.1 0.7 0.1 O.1 0.2 0.9 1.1 0.2 0.3 0.1 4.9 0.1 0.2 0.1 0.1 0.2 0.1 125 96 4 1 31 2 42 8 16 1 1 10 3 0 31 0 1 0 0 0 1 0 0 1 O 0
% 2001 Multichange attribute Index 2000 Multi 2000 to [col. E+F+G+H] Index 2001
118 66 1.3 53 2.2 53 8.0 53 3.4 113 3.4 113 16.3 34 27.8 45 0.0 65 7.9 38 0.9 46 7.9 38 1.4 33 12.4 26 6.7 26 2.5 35 1.8 35 1.8 35 0.7 30 7.6 13 8.1 13 173 20 2.6 17 1.9 113 7.2 84 10.9 88 3.7 53 16.9 35 12.0 16 1.2 36 6.2 43 10.3 35 0.6 46 1.3 35 1.3 36 1.9 30 1.4 16 1.5 20 175 121 37 216 200 300 200 276 143 134 15 143 39 162 18 102 30 214 41 271 54 123 13 86 118 94 11 214 26 61 4 150 4 150 0 133 1 124 7 34 24 71 0 37 0 10 8 50 i 35 0 20 Average change 2000-2001
386 254 185 151 118 117 84 82 66 47 48 46 42 39 37 38 37 37 32 21 21 207 121 115 114 102 80 73 68 67 62 55 48 42 37 34 27 22 621 549 509 489 368 360 342 329 326 324 321 308 266 230 168 161 159 146 128 118 105 55 10 167 37 21
384 251 197 162 175 175
0.5% 1.2% -6.4% -7.3% -32.7% -32.0%
82 68
0.0% -3.3%
51 94 50 46
-5.6% -51.1% -14.5% -15.0%
48 47 47
-21.2% -21.0% -21.6%
43 43
.50.1% .50.4%
165 147 127 132 106 103
-27.0% -21.4% -10.4% -23.0% -24.0% -29.5%
108 77 60 74
-37.7% -19.9% -8.2% -36.1%
78
-52.5%
48 620 542 482
-54,1% 0,2% 1.3% 5.6%
401 355 340 339 307 288 320 339 271 205 204
~.3% 1.3% 0.7% -2.8% 6.1% 12.6% 0.2% -9.1% -1.9% 12.1% -17.6%
159 137 172 123 109 59 10 205 42
0.0% 6.2% -25.7% 4.3% -3.5% -7.7% 0.0% -18.5% -12.0% -14.3%
194
AMERICAN JOURNAL OF POTATO RESEARCH
Vol. 79
potato production. For 19 of 67 active ingredients studied,
fungicide (National Agricultural Statistics Service 2000). The low
BioIPM values account for over 90% of multi-attribute toxicity
toxicity factor value for azoxystrobin (46, Table 4) and its low
factor values. The ecological toxicity component accounts for
application rates (0.11 lbs ALIA) combine to generate only five
the smallest share, just under 13%, while the two mammalian
toxicity units per acre-treatment, compared with about 185 and
toxicity components account for about 23%. Multi-attribute tox-
254 toxicity units from typical 1-1bapplications of mancozeb and
icity factor values per pound of active ingredient in Table 4 vary
metiram, respectively. Adoption of azoxystrobin largely
from below 40 for several fungicides, a few herbicides, and the
accounts for the 19% drop in fungicide toxicity units per acre in
foliar insecticide Bacillus thuringiensis, to as high as 621 for
1999 compared to 1995. In part because azoxystrobin must be
the organophosphate insecticide phorate (used rarely in Wis-
alternated with broad-spectrum fungicides to avoid selection for
consin).
resistance, chlorothalonil and metiram use increased in 1999 relative to 1995. As growers learn to use newly registered low-risk
RESULTS AND DISCUSSION
strobilurin fungicides in rotation with established products such as chlorothalonil and new fungicides In development, further
Further work is clearly needed to refine the formulas used
reductions in toxicity units from disease management should be
to calculate subindices and indices and in seeking out more
achieved. However, since there are concerns for the develop-
robust data on pesticides used in Wisconsin potato production.
ment of resistance to these new fungicides, they must be applied
The selection of scaling and weighting factors have a significant
in rotation with chemistries with different modes of action to
impact on relative multi-attribute factor values and stem from
maintain the effectiveness of the reduced-risk materials as long
subjective judgments that another group of people might view
as possible.
differently. Still, a wide variety of equations and assumptions
Toxicity units associated with insecticide use varied con-
would likely produce a similar relative ranking of pesticide tox-
siderably between years (Table 5). In 1997, a 62% decrease in
icity, since the most toxic pesticides are so much more toxic
total toxicity tmits per planted acre occurred, resulting largely
than most other active ingredients in most of the parameters
from the registration of imidacloprid in 1995. The excellent effi-
included in this analysis.
cacy of imidacloprid against key potato pests, including the Col-
The purpose of active-ingredient-specifictoxicity factor val-
orado potato beetle, Leptinotarsa decemlineata (Say), green
ues is to set goals and monitor changes in aggregate industrywide pesticide toxicity units, capturing changes in both the
peach aphid, Myzus persicae (Sulzer), and potato aphid, Macrosiphum euphorbiae (Thomas), resulted in widespread
pounds of active ingredient of pesticide applied and the toxicity
application of infidacloprid and accompanying reductions in the
of pesticides relied upon most widely. Toxicity units are calcu-
use of insecticides that had been targeted at these pests previ-
lated by multiplyingthe pounds of active ingredient of each pes-
ously. The most significant changes in insecticide use included
ticide applied by its multi-attribute factor value and are a
elimination of azinphos-methyl, carbofuran and oxamyl, an 83%
measure of potential adverse impacts likely to be associated
reduction in endosulfan toxicity, and, a 75% reduction in
with pesticide use over time. Once multi-attribute toxicity fac-
methamidophos toxicity units. The total drop in insecticide tox-
tors are set, changes in the mix of pesticides applied and the
icity units would have been greater if growers had not needed to
pounds of active ingredient applied of various pesticides
almost triple the pounds of active ingredient applied of
account for all variability in toxicity units.
dimethoate for potato leafhopper, Empoasca fabae (Harris),
Table 5 summarizes industry-wide trends since 1995 in reducing pesticide use and aggregate toxicity units by active
control in 1997 (Wyman et al. 1998). Toxicity units per acre from insecticide use rose from 279 in
ingredient and type of pesticide. Toxicity traits per planted acre
1997 to 505 in 1999, still a 31% decline from the 1995 baseline.
resulting from fungicide use declined 4% and 19% in 1997 and
The increase in insecticide use in 1999 also resulted from intense
1999, respectively, compared with the 1995 baseline and despite
pest pressure from potato leafhopper, which migrated into Wis-
severe pathogen pressure (Stevenson and James 1998). In 1997
consin earlier and in higher numbers than had been previously
there was less use of mancozeb but greater reliance on
recorded, along with heavy Colorado potato beetle pressure
chlorothalonil, resulting in little change in fungicide toxicity
(Wyman et al. 1998). Imidacloprid use increased by 43% over
units. In 1999 azoxystrobin was registered and 83% of potato
1997, but high Colorado potato beetle populations in fields not
acreage was treated an average of three times with this low-risk
treated with imidacloprid required more foliar applications than
2002
BENBROOK, eta/.: PESTICIDE RISK ASSESSMENT
195
TABLE 5---Industry-wide Wisconsin potato pesticide use and toxicity units: 1995, 1997, and 1999. Acresplanted 1995:83,000 1997:78,000 1999:86,000
Toxicity factorvalues
Herbicides: glyphosate linuron metolachlor metribuzin pendimethalin rimsulfuron sethoxydhn
1995 pounds appSed
1995 toxicity units
1997 pounds app~ed
1997 toxicity units
1999 pounds appfied
1999 toxicity units
3,000 1,000 16,000 37,000 21,000 1,0(D 5,000 84,000 0.98
lll,00O 62,000 352,000 4,218,000 2,142,000 115,000 240,000 7,240,000 84
37 62 22 114 102 115 48
4,000 7,000 21,000 39,000 24,000 0 2,000 97,000 1.17
148,000 434,000 462,000 4,446,000 2,448,000 0 96,000 8,034,000 97
9,000 3,000 7,000 34,000 16,000 0 O 69,000 0.88
333,000 186,000 154,000 3,876,000 1,632,000 0 0 6,181,000 79
326 368 321 360 266 509 159 329 342 324 105 55 230
26,000 13,000 0 11,000 60,000 3,000 0 69,000 5,000 4,000 0 3,000 166 194,160 2.3
8,476,000 4,784,000 0 3,960,000 15,960,000 1,527,000 0 22,701,000 1,710,000 1,296,000 0 165,000 38,180 60,617,180 730
0 0 0 30,000 10,000 2,000 8,000 17,000 0 0 0 7,000 0 74,000 0.95
O 0 0 10,800,000 2,660,000 1,018,000 1,272,000 5,593,000 0 0 0 385,000 0 21,728,000 279
6,000 0 5,000 27,000 53,009 6,000 14,000 15,000 5,000 1,000 27,000 18,000 68 177,068 226
1,956,000 0 1,605,000 9,720,000 14,098,000 3,054,000 2,226,000 4,935,000 1,710,000 324,000 2,835,000 990,000 15,640 43,468,640 505
46 21 82 38 37 42 185 151 117 118 254 48 386
0 13,000 408,000 40,000 12,000
0 273,000 33,456,000 1,520,000 444,000 17,940 76,220,000 11,476,000 0 472,000 0 432,000 4,632,000 128,942,940 1,554
0 8,000 591,000 52,000 2,000 5,000 287,000 62,000 0 0 0 0 8,000 1,015,000 13
0 168,000 48,462,000 1,976,000 74,000 210,000 53,095,000 9,362,000 0 0 0 0 3,088,000 116,435,000 1,493
22,000 25,000 501,000 14,000 0 5,000 278,000 0 3,000 3,000 49,000 0 2,000 902,000 10
1,012,000 525,000 41,082,000 532,000 0 210,000 51,430,000 0 351,000 354,000 12,446,000 0 772,000 108,714,000 1,264
28,000 7,000 13,000 970,000 3,000 1,632,000 2,653,000 32
2,044,000 385,000 481,000 161,990,000 240,000 34,272,000 199,412,000 2,403
26,000 0 0 0 0 2,770,000 2,796,000 35.8
1,898,000 0 0 0 0 58,170,000 60,068,000 770
46,000 5,000 0 0 0 0 51,000 0.59
Herbicides, insecticides, and fungicides Total: H+I+F per planted acre
1,277,166 15.4
197,594,120 2,381
1,158,000 i4.8
144,344,0(O 1,851
1,163,068 13.5
159,422,640 1,854
All chemicals Total per planted acre
3,930,166 47.4
397,006,120 4,783
3,954,000 50.7
204,412,000 2,621
1,214,068 14.1
159,492,840 1,855
Total: all herbicides per planted acre Insecticides: azinphos-methyl carbofuran Diazinon dimethoate endosulfan esfenvalerate imidachloprid methamidophos oxamyl permethrin phosmet piperonyl butoxide pyre~
Total: all insecticides per planted acre Fungicides: azoxystrobin basic copper sulfate chlorothalonil copper hydroxide copper resinate cymoxanil mancozeb maneb mefenoxam metalaxyl metiram propamocarb hydrochloride triphenyltin hydroxide Total: all fungicides per planted acre Other chemicals: diquat endothall maleic hydrazide metam-sodinm paraquat sulfuric acid
73 55 37 167 80 21
Total: other chemicals per planted acre
412,000 76,000 0 4,000 0 9,000 12,000 986,000 12
56,160 0 0 O 0 14,040 70,200 0.82
196
AMERICAN JOURNAL OF POTATO RESEARCH
typically needed. As a result, endosulfan use increased almost
Vol. 79
toward specific reduction goals such as those set forth in Lynch
to 1995 levels, esfenvalerate use doubled compared to 1995 lev-
et al. (2000). The collaboration's first year goal was to reduce
els (accompanied by an 500OAincrease in piperonyl butoxide to
the toxicity units associated with use of 11 targeted pesticides by
combat resistance) and small acreages were treated with azin-
20%, a goal exceeded by the 28% reduction in toxicity units in
phos-methyl, oxamyl and phosmet.
1977 (Lynch et al. 2000). The three-year goal called for a 40~ tox-
The year-to-year variability in toxicity units associated with
icity unit reduction by 1999 from the 1995 baseline; the actual
insect control reflects the routine, often extreme variability in
reduction was 37%. This reduction was achieved despite
insect population pressure. Our experience in Wisconsin con-
increases in 1999 insecticide use that erased 21.8 million of the
firms that fluctuations in individualpesticide use patterns should
38.9 million decline in insecticide toxicity units that had
be anticipated and that three- to five-year average measures of
occurred from 1995 to 1997 (Table 5).
pesticide use should be tracked whenever possible in large-scale
Toxicity units are also useful when analyzing changes in
IPM implementation and pesticide risk reduction projects. Oth-
pest pressure and pesticide product availability and efficacy. In
erwise it is likely that growers, researchers, and other stake-
2001, the collaboration is taking another step in ongoing efforts
holders will be overly encouraged in years when population
to capture market place rewards for grower innovation. IPM
pressure is low, and inappropriately alarmed over use in years
adoption and pesticide toxicity unit-based ecolabel standards
when populations are high. Projects need to focus on the over-
have been established for fresh market potatoes (Sexson and
all trend in average per acre toxicity units, a measure that has
Dlott 2001). About 20 growers worked in the 2001 season to
clearly declined over the last five years in Wisconsin potato pro-
meet the ecolabel standards and a third-party certifier has
duction, despite sometimes quite dramatic year-to-year swings
assessed progress. Growers producing short-season fresh mar-
and an increase in blight disease pressure. Newly registered low-
ket potatoes (less than 90 days from emergence to vine-kill)
risk insecticides such as spinosad for Colorado potato beetle (8
must remain within a cap of 800 total toxicity units per acre for
toxicity units/application) and pymetrozine for aphids (20 toxi-
the season; long-season growers (more than 90 days from emer-
city units/application) will continue to contribute to this down-
gence to vine-kill) must remain under 1,200 toxicity units. In
ward trend in average toxicity units per acre.
2001, participating fresh market growers within 25 miles of a
Toxicity units associated with herbicide use are relatively
field with late blight will have 400 more toxicity units to cover
low with current weed management systems. Major products
fungicide use if 18 severity values for late blight are reached on
applied are metribuzin (58 toxicity units/application), rimsul-
their farm by 1 June, or 200 more traits if late blight hits 18 sever-
furon (3 toxicity units/application) and sethoxydim (9 toxicity
ity values by 15 June. These adjustments reflect a first attempt to
units/application), and variable and less frequent use of meto-
build pest pressure into the measurement system. Other adjust-
lachlor (43 toxicity units/application), linuron (31 toxicity
ments are likely to be developed and applied in the future.
traits/application') and pendimethalin (85 toxicity units/applica-
In addition all ecolabel progrmn growers need to comply
tion). Weed management typically generates a total of 80-110
with a "Do Not Use" list including 12 active ingredients (aldicarb,
toxicity units/acre. Metribuzin and pendimethalin use have
azinphos-methyl, disulfoton, methamidophos, carbofltran~ car-
remained relatively constant since 1995 and account for the bulk
baryl, oxamyl, endosulfan, phorate, diazinon, permethrin, and
of herbicide toxicity units (Table 5). Rimsulfuron was registered
paraquat). Resistance management con(iitions are placed on
during this period and represents an effective low toxicity her-
several other moderate- to high-risk pesticides including
bicide alternative that has been widely adopted by growers. Con-
dimethoate, esfenvalerate, the EBDC fungicides, triphenyltin
cerns over resistance and the spectrum of weeds controlled,
hydroxide, azoxystrobin, and the soil flLmigant metam-sodium.
however, dictate that rimsuifuron be used in combination with
Ecolabel growers also face IPM implementation chal-
other herbicides and thus limit its potential to reduce toxicity
lenges. Short-season growers must score a minimum of 204
units.
points in an IPM practices survey, and long-season growers must score 211 points if the potatoes are being stored. Short
Using Toxicity Values to Obtain Marketplace Rewards
season growers who do not store their potatoes must receive 195 points and long season growers must earn 202 points. The
Toxicity factor values coupled with pesticide use data have
points are derived from an extensive survey of IPM practices,
proven useful in determining grower and industry-wide progress
with each practice assigned weights (points) reflecting its
2002
BENBROOK, eta/.: PESTICIDE RISK ASSESSMENT
importance in supporting progress along the IPM continuum (Sexson and Dlott 2001).
197
Two insect management approaches involving foliar and systemic insecticides were evaluated. Insect populations were moderate in this field. Colorado potato beetle larvae in the con-
Evaluating Reduced-risk Transition Strategies in Commercial Potatoes In addition to activities supporting the emergence of ecola-
ventional foliar program required one application of esfenvalerate for first generation control, timed to target second instar larvae and a follow-up application of cyfluthrin for second-gen-
beled Wisconsin potatoes in 2001, growers, crop consultants,
eration larvae. In the reduced-risk foliar program two applica-
and University of Wisconsin pest management specialists are
tions were also required using spinosad and Bacillus
currently developing and testing multitactic transition strategies
thuringiensis subsp, tenebr/qn/s. Toxicity units were 55% lower
applicable to major potato pests. Toxicity factor values, coupled
in the reduced-risk foliar program and costs were increased by
with data on costs per acre treated with alternative pesticides
$12 per acre. Both programs held Colorado potato beetle larvae
or cultural practices, are proving helpful in evaluating the poten-
at low levels throughout the season and no defoliation was
tial impact of various pest management system changes.
recorded. Potato leafhopper populations were held below
Reduced-risk insect and disease management programs integrating the basic components of successful potato IPM (crop
threshold (1 adult/sweep) with a single insecticide application in both programs. Aphids did not require treatment.
scouting, pest prediction, and thresholds) with use of low-toxi-
In the systemic treatment evaluation, imidacloprid per-
city pesticides have been developed with growers and tested in
formed well in both conventional and reduced-risk programs
large-scale replicated trials. Various insect and disease manage-
(where the imidacloprid rate was reduced) with few larvae and
ment programs have been evaluated separately and in combina-
no defoliation observed. Potato leafhoppers required one appli-
tion on 12 commercial fields in 2000 and 2001. Data follow from
cation in both programs to hold adults and nymphs below
a combined insect/disease evaluation conducted in central Wis-
threshold. Toxicity units were 31% lower in the reduced-risk pro-
consin in 2000. Russet Burbank variety potatoes were planted
gram and pesticide costs were also $10 per acre lower.
on 25 April 2000 in a center-pivot irrigated field at Coloma~ Wis-
The impact of the combined insect and disease programs
cousin. Conventional and reduced-risk foliar disease programs,
on yield and costs are shown in Tables 6 and 7. For systemic
combined with conventional and reduced-risk systemic (Table
insect and foliar disease control, the reduced-risk program was
6) and foliar (Table 7) insect programs were applied to 48-row x
more expensive ($32 per acre), but yield was significantlyhigher
1200-ft plots (3.3 acres) replicated three times in a randomized
(15 cwt/A) as a result of the improved early blight control asso-
complete block design. Treatment decisions were based on
ciated with use of azoxystrobin. The cost of the reduced-risk
weekly scouting and disease prediction and pesticide applica-
program per cwt was only marginally higher (5.6 cents per cwt)
tions were made by the grower.
(Table 6), and at a $5/cwt selling price this reduced-risk program
Disease pressure was high in 2000 with moderate early blight in the field and late blight in the immediate vicinity. Late
would thus result in a net gain of $43/A. The toxicity units associated with this progrmn were reduced by 51% (Table 6).
blight severity valves passed the threshold of 18 in early June, and spray programs were initiated on 9 June and continued on a 7-day schedule until 5 September. The conventional fungicide program required 17 applications, primarily mancozeb,
TABLE6---Cost/benefit of reduced-risk pest control,. Coloma,
wi, 2ooo.
clilorothalonil, and tin and cost $111 per acre. Toxicity units totaled 2,421 per acre, about twice the level allowed in the ecolabel standard for season-long potatoes. The reduced-risk pro-
Fungicide/systemic insecticide Program
gram used three applications of azoxystrobin in early season in rotation with chlorothalonil and relied on chlorothalonil thereafter for a toxicity unit total of 1,169 (60% reduction) at a cost of $153 per acre (27% increase). Disease control was more effective in the reduced-risk program with significantly lower incidence of early blight. No late blight was found in either program.
Conventional Reduced risk Outcome of reduced risk
Cost of materials (S/A)
Yield (cwt)
$182 $214 + $32 / Acre
443 b 458 a + 15 cwt
Cost/cwt Toxicity (cents) units 41.8 46.7 + 5.6/cwt
2,494 1,242 -1,252
Bottom line: Reduced risk costs 5.6 cents/cwt more, but the net financial gain from reduced-risk programs (@$5.00/cwt)is $43/A
198
AMERICAN JOURNAL OF POTATO RESEARCH
TABLE7--Cost/benefit of reduced-risk pest control, Coloma, wI, 2000.
Conventional Reduced risk Outcome of reduced risk
or industry-wide, through targeted research, use of n e w pesticide chemistry, and IPM implementation. A longer-term goal is e s t a b l i s h m e n t of an information base to forge c o n s e n s u s on
Fungicide/foliar insecticide Program
Vol. 79
Cost of materials (S/A)
Yield (cwt)
Cost/cwt (cents)
Toxicity units
$136 $190 + $54/Acre
444 b 464 a + 20cwt
30.6 40.9 + 10.3/cwt
2,557 1,229 -1,328
future regulatory, research, and education priorities.
ACKNOWLEDGMENTS This w o r k by the WWF-WPVGA-UW potato IPM team was made possible by financial support from the Wisconsin Potato
Bottom line: Reduced risk costs 10.3 cents/cwt more, but the net financial gain from reduced-risk programs (@$5.00/cwt) is $46 / A
and Vegetable Growers Association, the C.S. Mott Foundation, the J o y c e Foundation, the Wisconsin Pesticide Use and Risk Reduction Program, and the U.S. D e p a r t m e n t of Agriculture. M e m b e r s of the project's advisory and technical c o m m i t t e e s
For foliar insect and disease control (Table 7), reduced-risk
have provided invaluable information and guidance. Thanks to
program costs were $54 per acre higher, reflecting the increased
Benbrook Consulting Services for compiling and maintaining the
c o s t of l o w - r i s k foliar i n s e c t i c i d e s , but yields w e r e again
underlying databases.
increased (20 cwt/A), and the cost/cwt was increased by only 10.3 cents/cwt (Table 7). At $5/cwt, the reduced-risk foliar pro-
LITERATURE CITED
gram would result in a net gain of $46/A to growers based on the significant yield increase achieved. Toxicity units associated with the reduced-risk foliar program were reduced by 1,328 per acre (52%).
CONCLUSIONS Pesticides pose highly variable environmental and human health risks. A wide range of activity is underway to p r o m o t e more biologically based, less disruptive and hazardous pest management systems. Most entail setting goals for reduction in highrisk pesticide use and/or IPM adoption, and w a y s to monitor progress. All will*oenefit from n e w tools to track changes in the toxicity of pesticides required to support a given IPM system (Ehler and BottreU 2000). The toxicity-unit methodology developed by the collaborative potato project in Wisconsin has produced information now serving several useful purposes. Progress in reducing reliance on high-risk pesticides has b e e n monitored since 1995. Tradeoffs are m a d e e x p l i c i t as n e w p e s t i c i d e s and t e c h n o l o g i e s replace older, higher-risk products. Growers and researchers are calculating the per acre toxicity units associated with alternative IPM systems. By factoring cost consequences into the equation, the Wisconsin project is working toward analytical tools r e s p o n ~ v e to the needs of both farmers and environmentalists. Despite data gaps and less than complete coverage of environmental and BioIPM impacts, the methodology does highlight the potential to reduce the impact of pesticides on a given field,
Agricultural Marketing Service. 1996. Pesticide Data Program: Annual Summary Calendar Year 1994. USDA, Washington. 71 pp. Barnard, C., S. Daberkow, M. Padgitt, M.E. Smith, and N.D. Uri. 1997. Alternative measures of pesticide use. Sci Total Envir 203:229-244. Benbrook, C., E. Groth, J. Halloran, M. Hansen, and S. Marquardt. 1996. Pest Management at the Crossroads. Consumers Union, Yonkers. pp. 196-204. Bigbee, J.W., K.V. Sharma, J.J. Gupta, and J.L. Dupree. 1999. Morphogenic role for acetylcholinesterase in axonal outgrowth during neural development. Environ Health Persp 107(Suppl 1): 81-87. Brent, K.J. 1995. Fungicide resistance in crop pathogens: how can it be managed, FRAC, Monograph No. 1:52 pages. CGPF, Brussels. Brent, ILJ., and D.W. HoUomon. 1998. Fungicide resistance: the assessment of risk., FRAC Monograph No. 2:150 pages. CGPF, Brussels. Brucker-Davis, F. 1998. Effects of environmental synthetic chemicals on thyroid function. Thyroid 8(9): 827.856. Burnam, W. 1999. Office of Pesticide Programs list of chemicals evaluated for carcinogenic potential, Memorandum, August 25. Office of Pesticide Programs, US EPA. Colborn, T., F.S. vom Saal, and A.M. Soto. 1993. Developmental effects of endocrine
