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Crop Protection 25 (2006) 1101–1108

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Variation in pesticide hazard from arable crop production in GreatBritain from 1992 to 2002: Pesticide risk indices and policy analysis

Paul Cross, Gareth Edwards-Jones�

School of Agricultural and Forest Science, University of Wales Bangor, Gwynedd, North Wales LL57 2UW, UK

Received 17 February 2006; accepted 27 February 2006

Abstract

Attempts to direct policy according to scientific findings are hampered by the multidimensionality of the potential impacts of pesticides

which may affect consumers, operators, wildlife and the environment. Pesticide risk indices seek to reduce these multidimensional

impacts to a single dimension and are increasingly used to understand variation in the hazard inherent in pesticides at the farm, regional

and national scale. In this study, we used one such risk index, the Environmental Impact Quotient (EIQ), to estimate the hazard posed by

pesticide usage from 1992 to 2002 on four UK grown arable crops (wheat, winter barley, spring barley and oilseed rape).

Results are reported for three key indicators of hazard. Firstly, the EIQ which rates a pesticide’s hazard profile. Secondly, the

Environmental Impact (EI) which is the product of the EIQ rating and data on actual usage of a pesticide at a GB level in a given year,

and provides an indication of the overall hazard arising from actual historical use at a national scale. Thirdly, EI per hectare standardises

the hazard by dividing total EI in year by the area of crop grown in that year.

The results suggest that between 1992 and 2002, the overall hazard posed by the pesticides applied to these crops declined substantially,

as evidenced by a 10% decrease in pesticide usage, an 8% increase in yield per hectare, a 14% decrease in overall EIQ rating, a 15%

decrease in EI rating and a 7% decrease in EI per hectare. Both Government and the industry may wish to take some encouragement

from these trends, which seem to be wholly in line with societal demands of agriculture.

r 2006 Elsevier Ltd. All rights reserved.

Keywords: Pesticides; Voluntary initiaitve; Policy; Risk; Arable crops; EIQ

1. Introduction

There is a growing societal desire to reduce the use ofpesticides in agriculture and horticulture (Beaumont, 1993;Freidberg, 2003; Pretty and Hine, 2005). As a result, boththe agrochemical industry and farmers are under pressureto adapt to a changing consumer preference that perceivespesticides as an undesirable component of food produc-tion. However, as yet there is no agreed method formeeting societal desires in an equitable and scientificallydefensible manner.

Traditionally, governmental policy decisions relating tothe rationalisation of pesticides have generally focussed onseeking a decreased overall use of pesticides, coupled withthe banning of certain highly toxic substances (Levitan,

e front matter r 2006 Elsevier Ltd. All rights reserved.

opro.2006.02.013

ing author. Tel.: +441248 382441; fax: +44 1248 354997.

ess: g.e.jones@bangor.ac.uk (G. Edwards-Jones).

2000; Gallivan et al., 2001; Freidberg, 2003). One recentidea which seeks to break from this traditional approach topesticide regulation relates to the development of apesticide tax (Quin and Edwards-Jones, 1997). Implicit inthis idea is the concept of linking the toxicity of a particularpesticide to the amount of tax levied, where the greater thetoxicity of a pesticide, the greater the tax. However, thereare major difficulties in establishing such a tax, and one ofthese relates to the exact nature of the ‘toxicity’ which is tobe taxed. For example, should the tax reflect toxicityrelevant to consumers, farmworkers, the aquatic environ-ment, non-target invertebrates or some combination of allthese factors?The use of so-called ‘pesticide risk indices’1 could help in

this situation as these indices generally combine a range of

1Note that generally ‘risk’ is defined as the probability of an event

multiplied by the magnitude of the outcome of that event. As such, none

ARTICLE IN PRESSP. Cross, G. Edwards-Jones / Crop Protection 25 (2006) 1101–11081102

measurable toxicological data pertaining to a specificpesticide into a single figure or rating. After undertakingthis process for a range of pesticides, it then becomespossible to perform a comparative assessment of the risk orhazard posed by these pesticides (Levitan et al., 1995;Levitan, 1997; Quin et al., 1999; Levitan, 2000; Maud et al.,2001). When employed in this way, these indices mayfacilitate decision-making between different pesticides for arange of uses such as selecting between different productsat field level, setting levels for a pesticide tax and assessinga posteriori hazards posed by pesticides at a regional ornational level.

When using risk indices in these contexts, it is importantto recognise that each index possesses its own particularmerits and failings, and consideration of these is integral tocomprehending their outputs. However, regardless of thespecific problems relating to any one method, risk indicesdo offer a transparent and consistent analytical frameworkwhich enables comparative assessment of trends inpesticide risk over time or between crops. It is for thisreason that they offer great utility in policy analysis.Further, the need for an absolute rating that in somewayrepresents the actual hazards associated with pesticide useis less vital than ensuring that the same rating methodologyis applied between years. Consequently, the figures derivedfrom the study do not in anyway represent the exact hazardpresent in GB at any one time. Rather, they lendthemselves more readily to time-dependant comparisons.

While the use of pesticide risk indices in developingpesticide tax regimes have been discussed previously (Quinand Edwards-Jones, 1997; Falconer, 1998, DETR, 1999;Falconer and Hodge, 2000), they may also aid in theanalysis of the initiative which the UK Government choseto implement instead of a pesticide tax: The VoluntaryInitiative (VI). The VI was initiated in 2000 when the UKGovernment invited the UK trade representatives for theagrochemical industry, the Crop Protection Association, topresent a number of measures to reduce the EnvironmentalImpact (EI) of pesticide use. The VI was born of thisconsultation, and in essence it requires the agrochemicalindustry and farmers to work together to reduce the impactof pesticide use and improve the biodiversity of arablefarmland in the UK (for further details see http://www.voluntaryinitiative.org.uk). There are 28 agreedtargets which include the development of crop protectionmanagement plans and to have 30% of arable landengaged in their use by 2006; awareness raising amongst

(footnote continued)

of the so-called ‘risk indices’ reported in the literature for pesticides are

strictly indices of risk, because none incorporate either an estimate of

probability of an event or an estimate of magnitude. Rather they are more

correctly indices of ‘consequences of hazard’, where a hazard is ‘a property

or situation that in particular circumstances may cause harm’ and

consequences are ‘the adverse effects of realising a hazard, which cause the

quality of human health or the environment to be impaired in the short or

longer term’. However, given the common use of the phrase ‘risk indices’

in the literature, this phrase is also used throughout this paper.

spray operators of safe use of pesticides; and to work withWater UK and the Environment Agency with the aim oftargeting ‘catchments’ that face significant problems. Threecriteria were established for monitoring progress under theVI: protecting water, benefiting biodiversity and changingfarmers’ and pesticide applicators’ behaviour (CPA, 2005).While these objectives are perhaps more meaningfulendpoints for a pesticide policy than simple reductions involumes used, they are rather more difficult to monitor.Partly as a result of the absence of good monitoring data,measuring the achievements of the VI is proving con-troversial, and the Environment, Food and Rural AffairsCommittee suggested that there is a lack of ‘‘irrefutableevidence of the environmental benefits of the VI’’. Thesame committee went on to say that ‘‘DEFRA is not onlyunable to provide assurances on the environmental benefitsof the VI at this time, but appears to have little confidencein the usefulness of the research it commissioned specifi-cally to provide tools for this assessment’’ (para 48)(DEFRA, 2005b).One method to measure the success, or otherwise of the

VI or any other similar policy initiative, would be to use apesticide risk index which could be used to compare thehazard posed by the actual types and amount of pesticideused over a suitable time period. Ideally, the time period ofthe analysis would include some years in the pre- and post-policy implementation phases.It is against this background that this paper presents

trends in the overall hazard posed by pesticides applied tofour arable crops in the United Kingdom between 1992 and2002. This time period was selected as it corresponds withthe decade which began with the passing of the EuropeanUnion Agricultural Pesticides Directive (91/414) and endedwith the revocation of 320 pesticides in 2003. It alsoincludes 8 years of data prior to the introduction of the VI,and two post-VI. It therefore not only chronicles theimpact of pesticide reduction strategies during the 1990sbut also acts as a baseline by which future policy initiativesmight be judged.To enable consistent assessment of the changes in

hazards posed by pesticides in UK arable farming acrossthis time period, the Environmental Impact Quotient (EIQ)(Kovach et al., 1992) index was selected as a means ofestimating hazards. This decision was based upon threeprinciple criteria. Firstly, it has the ability to report thehazard to a range of endpoints separately (the endpointsare farmworker, consumer and environment). Secondly, itperformed relatively well in the comparative analysis ofrisk indices undertaken by Maud et al. (2001), and thirdly,it has been used in a number of other agricultural andhorticultural contexts which bestows a degree of confidencein its utility (Gallivan et al., 2001; Smith et al., 2002;Segarra et al., 2003; Bues et al., 2004; Brimner et al., 2005).Furthermore, this study is part of a broader researchprogramme that is comparing changes in pesticide hazardin the UK, Spain, Kenya and Uganda. Given therequirement for cross-national comparisons, the hazard-

ARTICLE IN PRESS

Table 1

Scoring scheme for the Environmental Impact Quotient variables

Key to EIQ categories Score

Acute dermal toxicity 42000 1

LD50mg/kg 200–2000 3

0–199 5

Chronic toxicity None 1

Reproductive Little 1

Teratogenic Possible 3

Mutagenic

Carcinogenic Definite 5

Bee toxicity 4100mg 1

2.0–100mg 3

o2.0 mg 5

Fish toxicity 410 ppm 1

96-h LC50 1–10 ppm 3

o1 ppm 5

Bird toxicity 41000 ppm 1

8-day LC50 101–1000ppm 3

1–100 ppm 5

Beneficial toxicity Low impact 1

Moderate impact 3

Severe impact 5

Post-emergent herbicide 3

Plant surface half-life (days) 0–14 1

15–28 3

428 5

Pre-emergent herbicide 1

Post emergent herbicide 3

Leaching and runoff Potential o1.8 1

Log(half-life)(4�log(Koc)) 1.8–2.8 3

42.8 5

Systemicity Non-systemic 1

Systemic 3

Herbicide 1

Source: adapted from Levitan (2000); Gallivan et al. (2001).Where bee

toxicity is not explicitly stated, then scores were assigned based upon

LD50 ratings. Where data was missing for beneficial arthropods, scores

were assigned based upon bee toxicity.

P. Cross, G. Edwards-Jones / Crop Protection 25 (2006) 1101–1108 1103

based Kovach model, which has standard data require-ment, was preferred over a risk-based approach, wheredata requirements may vary with location.

The crops chosen for study were wheat, spring andwinter barley and oilseed rape. In terms of area, these cropsdominate the arable landscape of the UK and in 2002, theycomprised an area of 3.53mha out of a total UK arablearea of 4.5mha. Unlike barley, analysis for wheat relatesto the entire wheat crop grown and is not disaggregatedinto spring and winter crops. This difference in reportingon barley reflects the treatise of the two crops in thepesticide usage survey reports.

The trends in hazard related to the pesticides used in theprotection of these widely grown crops are likely to have asubstantial influence on the overall hazard of pesticidesused in UK agriculture, but they do not comprise thecomplete picture. In order to fully understand the overallhazard arising from pesticide use in GB agriculture, itwould be necessary to combine the analysis conducted herewith similar analyses for all arable and horticultural crops.

2. Methods

2.1. EIQ scores

The EIQ provides a rating for the inherent hazard of apesticide to three non-target groups: farmworker, con-sumer and environment. A pesticide’s EIQ rating is theproduct of its component parts EIQfarmworker, EIQconsumer

and EIQecological. It is the mean of these three componentsfrom which the overall EIQ for a given pesticide is derived(Fig. 1). A complete list of the data required to calculate anEIQ is shown in Table 1.

A list of pesticides applied to each of the four crop typesbetween 1992 and 2002 was obtained from the 2-yearlypesticide usage survey reports undertaken at a GB level(Davis et al., 1993; Garthwaite et al., 1995; Thomas et al.,1997; Garthwaite and Thomas, 1999, 2001; Garthwaite et al.,2003). Scores for EIQ variables were obtained for many ofthese pesticides from internet sites such as ExtensionToxicology Network (EXTOXNET), the Integrated PestManagement Programme from Cornell University, IN-CHEM at the International Programme on ChemicalSafety (IPCS), the Canadian Centre for Occupational

Fig. 1. The Environmental Impact Quotient formula by Kovach et al. (1992) fo

used individually for assessing the hazard of a particular recipient group or th

C ¼ chronic toxicity, F ¼ fish toxicity, DT ¼ dermal toxicity, R ¼ surface loss

Z ¼ bee toxicity, Sy ¼ systemicity, B ¼ beneficial arthropod toxicity, L ¼ leac

Health and Safety (CCOHS) or from the study by Maud etal. (2001). Where possible, these previously calculatedscores were utilised in this study. Where data gaps existed,then manufacturers’ toxicity findings were used for those

r calculating the hazard posed by individual pesticides. Components can be

ey can be summed and divided by three to give the overall pesticide risk.

potential, S ¼ soil half-life, D ¼ bird toxicity, P ¼ plant surface half-life,

hing potential.

ARTICLE IN PRESS

0

1

2

3

4

5

6

7

8

9

1992 1994 1996 1998 2000 2002Year

Yie

ld t

on

nes

/ha-1

Wheat

Winter barley

Spring barley

Oilseed rape

Overall mean

Fig. 2. Mean yield for wheat, spring and winter barley and oilseed rape

for the period 1992–2002. Source: DEFRA National Statistics (2005a, b).

P. Cross, G. Edwards-Jones / Crop Protection 25 (2006) 1101–11081104

variables that input to the EIQ model. If these wereunavailable, then the mean values of known pesticideswithin the same chemical group were used to calculate asurrogate rating. Formulations were calculated using theUK pesticide handbook (Whitehead, 1996, 2001, 2003,2004).

2.2. Environmental Impact

EIQ ratings indicate the relative toxicity of a substance.However, this information alone is insufficient to form anassessment of its actual hazard to non-target endpoints, aseven the most toxic substance used over a wide area in verysmall quantities may pose only a minor hazard. Theconverse can also be said for a relatively benign substanceused extensively in terms of area and kilogrammes of activeingredient (a.i.). Therefore, to circumvent these problems,the EI is obtained by multiplying the EIQ of a givenpesticide by the number of kilogrammes of a.i. used. Thisvalue can then be used to make year-on-year comparisonsof changes in pesticide hazard.

The quantity of a.i. and pesticide spray area values foreach of the target crops were taken from the DEFRA 2-yearly pesticide usage surveys for arable crops (Davis et al.,1993; Garthwaite et al., 1995; Thomas et al., 1997;Garthwaite & Thomas, 1999, 2001; Garthwaite et al.,2003). Only those pesticides whose spray area and kilo-grammes of a.i. both exceeded 0.1% of the pesticide usagesurvey’s sample area were used to make comparisons.Furthermore, only pesticide usage for fungicides, herbi-cides, insecticides, molluscicides and growth regulator wereconsidered. Seed treatment, repellents and soil sterilantswere excluded from the analysis.

2.3. Arable crop production

As the EI rating is dependant upon both the pesticide’sinnate toxicity and the quantity used, it is important toplace EI changes within the context of changing arablecrop production. For example, an increase in overallpesticide hazard at a national level may be related directlyto an increase in the area of production rather than to anychanges in the amounts and type of pesticide used. In orderto separate the potential causes of any such change, the EIper hectare are calculated and considered alongsidechanges in the areas of crop grown. To enable thiscomparison, data on arable crop production (quantityand area) since 1992 were obtained from the DEFRANational Statistics website (DEFRA, 2005a).

3. Results

Pesticide use (defined here as weight of pesticideapplied), EIQ ratings and EI ratings declined between1992 and 2002, but the degree of change varied with crop.Yields appear to be unaffected by reduced pesticide use,

having increased at differing rates over the same period(Fig. 2).

3.1. Arable crop production

The overall yield from UK arable crop production(expressed in tonnes) increased by 4% between 1992 and2002. Winter barley declined by 29% whilst wheat, springbarley and oilseed rape increased by 13%, 6% and 21%,respectively. The combined mean yield (tonne ha�1) for thefour crops increased by 8% from 5.20 tonne ha�1 in 1992 to5.64 tonne ha�1 in 2002. The largest increase was foroilseed rape (18%) from 2.88 tonne ha�1 to 3.40 tonne ha�1

whilst spring barley decreased by 2% (4.95 tonne ha�1 to4.86 tonne ha�1) (Fig. 2).

3.2. Pesticide use

The number of a.i. and formulations used on the fourcrops increased from 103 in 1992 to 111 in 2002. Thenumber of a.i. and fungicide formulations used increasedfrom 40 to 45, as it did for herbicides (43 to 47). However,the number of a.i. used as insecticides decreased from 14 to9. The amount of fungicide used decreased by 59% from3,964,490 kg in 1992 to 1,629,660 kg in 2002, whilstspray area increased 14% from 10,360,957 ha�1 to11,830,385 ha�1. Herbicide use increased 8% from6,048,680 kg to 6,530,670 kg, while the spray area increased46% from 7,370,472 ha�1 to 10,744,580 ha�1. Insecticideuse decreased 49% from 186,050 kg to 94,560 kg, while thespray area increased 20% from 2,680,878 ha�1 to3,218,741 ha�1.Pesticide use on target crops, as measured by kilo-

grammes of a.i., decreased by 13% between 1992 and 2002.Pesticide use on wheat declined 7%, in spite of a 37%

ARTICLE IN PRESSP. Cross, G. Edwards-Jones / Crop Protection 25 (2006) 1101–1108 1105

increase in spray area over the same period. Pesticideuse on winter barley decreased 24%, accompanied bya 2% decrease in the spray area (Table 2). The meanpesticide application rate across all four crops decreased by39%, with the mean application rate for oilseed rapedeclining by 64%, and by 36% for wheat. The smallestchange in rates was for spring barley, with a decreaseof 21% (Fig. 3).

3.3. Environmental Impact ratings

The overall mean EIQ rating of the four crops decreasedby 14% from 1992 to 2002. The mean EIQ for oilseedrape decreased by 18%, but only by 2% for spring

Table 2

Pesticide use, Environmental Impact Quotient and environmental impact valu

Measure Crop 1992 1994

Area (ha�1� 103) Wheat 2067 1811

Winter barley 784 627

Spring barley 514 481

Oilseed rape 421 491

Total 3786 3411

Weight (� 103) Wheat 14 095 13 316

Winter barley 4821 3650

Spring barley 2543 2300

Oilseed rape 1213 1243

Total 22672 20509

Pesticide use

(kg� 106) and spray

area (ha� 106) in

brackets

Wheat 89 (155) 78 (152)

Winter barley 25 (44) 20 (50)

Spring barley 6 (14) 7 (15)

Oilseed rape 8 (17) 7 (15)

Total 128 (230) 112 (232)

EIQ ratings Fieldworker 21.88 18.27

Consumer 11.01 11.17

Environment 68.33 67.58

Mean 33.74 32.34

Component EI

EI fieldworker (� 106) Wheat 1171 1131

Winter barley 307 252

Spring barley 109 123

Oilseed rape 95 75

EI consumer (� 106) Wheat 790 749

Winter barley 236 194

Spring barley 55 64

Oilseed rape 55 46

EI environmental

(� 106)

Wheat 4666 4558

Winter barley 1366 1104

Spring barley 354 394

Oilseed rape 462 449

EI (� 106) Fungicide 1292 1098

Herbicide 1334 1205

Insecticide 109 225

Molluscicide 37 92

Growth reg. 450 427

barley (Fig. 4). EIQ ratings for fungicides, herbicidesand insecticides decreased by 1%, 8% and 40%, respec-tively (Fig. 5). The mean EI rating for the four cropsdecreased by 15% with wheat decreasing by 12%, winterbarley by 31%, spring barley by 9% and oilseed rapeby 5% (Fig. 6). EI ratings for the three componentsalso decreased. The EIfarmworker rating decreased by 23%,the EIconsumer by 13% and the EIenvironmental by 14%(Table 2). The mean EI per hectare across all cropsdecreased by 7%. Spring barley showed the largestdecrease in EI per hectare (16%), but the EI per hectarefor winter barley remained unchanged. The EI per hectarefor wheat and oilseed rape declined by 9% and 8%,respectively (Fig. 7).

es for pesticides used on arable crops

1996 1998 2000 2002 % change

1992–2002

1976 2045 2086 1996 �0.03

749 772 589 546 �0.30

519 483 539 555 0.08

415 534 402 432 0.03

3659 3834 3616 3529 �0.07

16 100 15 449 16 704 15 973 0.13

4950 4290 3719 3431 �0.29

2830 2340 2773 2697 0.06

1415 1568 1157 1468 0.21

25295 23647 24353 23569 0.04

90 (178) 87 (198) 84 (242) 82 (213) �0.07 (0.37)

25 (49) 25 (54) 20 (46) 19 (43) �0.24 (�0.02)

5 (18) 5 (17) 6 (22) 6 (25) 0.05 (0.85)

7 (22) 8 (29) 6 (21) 7 (24) �0.03 (0.36)

128 (267) 125 (299) 117 (330) 115 (305) �0.10 (0.33)

19.49 17.32 15.99 15.25 �0.30

11.23 11.68 10.14 10.69 �0.03

68.39 68.88 62.35 61.56 �0.10

33.05 32.64 29.50 29.18 �0.14

1116 1055 937 903 �0.23

284 271 212 205 �0.33

89 82 89 96 �0.11

94 114 80 86 �0.09

808 742 740 707 �0.10

225 202 163 154 �0.35

50 48 46 50 �0.08

66 86 68 73 0.32

5176 4705 4373 4210 �0.10

1387 1342 1070 964 �0.29

364 288 296 322 �0.09

581 466 366 420 �0.09

1263 795 535 488 �0.62

1523 1628 1525 1527 0.14

100 132 62 43 �0.60

64 74 179 162 3.36

464 506 512 511 0.14

ARTICLE IN PRESS

0.00

0.10

0.20

0.30

0.40

0.50

0.60

1992 1994 1996 1998 2000 2002Year

Ap

plic

atio

n r

ate

(Kg

/ha-1

)

Wheat

Winter barley

Spring barley

Oilseed rape

Overall mean

Fig. 3. Mean application rate for wheat, spring and winter barley and

oilseed rape for the period 1992–2002.

26

27

28

29

30

31

32

33

34

35

36

Mea

n E

IQ s

core

s

1992 1994 1996 1998 2000 2002Year

Wheat

Winter barley

Spring barley

Oilseed rape

Overall mean

Fig. 4. Mean Environmental Impact Quotient (EIQ) ratings for wheat,

spring and winter barley and oilseed rape for the period 1992–2002.

0.00

0.20

0.40

0.60

0.80

1.00

1.20

Ap

plic

atio

n r

ate

(Kg

/ha-1

)

fungicide

herbicide

insecticide

molluscicide

growth regulator

1992 1994 1996 1998 2000 2002Year

Fig. 5. Mean application rate by pesticide type.

P. Cross, G. Edwards-Jones / Crop Protection 25 (2006) 1101–11081106

4. Discussion

The results suggest that between 1992 and 2002, theoverall hazard posed by the pesticides applied to thesecrops declined substantially, as evidenced by a 10%decrease in pesticide usage, an 8% increase in yield perhectare, a 14% decrease in the overall EIQ rating, a 15%decrease in the EI rating and a 7% decrease in EI per

0

50

100

150

200

250

300

350

400

EI

sco

re (

x106 )

1992 1994 1996 1998 2000 2002Year

Wheat

Winter barley

Spring barley

Oilseed rape

Total

Fig. 6. Total Environmental Impact (EI) ratings for wheat, spring and

winter barley and oilseed rape for the period 1992–2002 (Kovach et al.,

1992).

0

20

40

60

80

100

120

140

EI x

103 /

ha-1

1992 1994 1996 1998 2000 2002Year

Wheat

Winter barley

Spring barley

Oilseed rape

mean

Fig. 7. The Environmental Impact per hectare for wheat, spring and

winter barley and oilseed rape for the period 1992–2002.

ARTICLE IN PRESSP. Cross, G. Edwards-Jones / Crop Protection 25 (2006) 1101–1108 1107

hectare. Even though there were some crops which did notfit the overall pattern, such as spring barley which showeda slight decline in yield per hectare, both Government andthe industry may wish to take some encouragement fromthese achievements which seem to be wholly in line withsocietal demands of agriculture. The combination of lowerEIQ scores (pesticides are less toxic to humans and theenvironment than previously (Table 2)) and reducedquantities being applied (10% decrease in weight ofpesticide applied (Table 2) and a 33% increase in the areabeing sprayed, giving a 39% reduction in application rate(Fig. 3)) provides a substantial part of the explanation fordecreased EI per hectare.

However, some care is needed when interpreting theseresults and a number of caveats need to be borne in mindthat may have influenced the findings of this study. Firstly,EIQ ratings for a given pesticide can and do change overtime. As knowledge about the toxicity of a pesticideincreases over time, the EIQ is altered to accommodate anyfindings that diverge from the original laboratory tests thatwere required for product registration. In subsequent years,more research is published and toxicity ratings change toaccommodate the new findings. Thus, ratings, particularlyfor more recently registered substances, may alter overtime. Secondly, mean EIQ ratings for a given crop aresensitive to the addition or removal of just one pesticideirrespective of its level of use. Therefore, if just one highlytoxic pesticide is used in a given year but at the minimumquantity to qualify for the pesticide usage survey, then themean EIQ will be greatly increased whilst the EI mayremain relatively unchanged. Finally, 2-yearly pesticideusage surveys only offer a partial view of the changes thatmay be occurring in pesticide usage, and given thesensitivity of the pest complex to weather patterns, wewould expect an annual survey to show some year-on-yearvariation independent of any market or policy conditions.However, a study like this one which considers a 10-yeartime period is more concerned with long-term trends thanspecific inter-annual variation.

There are three trends apparent from this analysis whichhave some relevance to pesticide policy. Firstly, the EIQrating of pesticides used on the four crop types fellconsiderably over the period of study. So the policy ofsimultaneously banning particular toxic substances whileencouraging more benign products to be developed seemsto have had some effect. Partly as a result of this, the EI perhectare has also shown some decrease. This is a crucialpolicy indicator as it effectively measures the level ofhazard posed per standard unit area, and when coupledwith the increased yields it is apparent that in 2002, theproduction of one tonne of wheat, barley and oilseed rapewere posing substantially lower hazard to the British publicthan in 1992. Finally, the overall EI decreased by 15%,even though the area of crops grown only decreased by7%. This is an important point as one way to reduce thehazard from UK agriculture would be to restrict produc-tion in the UK, and simply import more food. Such a

policy would effectively be exporting the hazard related tofood production to elsewhere on the globe, and the ethicsof such a policy are unclear.While these results suggest that the policies which were

prevalent during the 1990s seem to have had a beneficialimpact on the hazard profile of pesticides applied to thesefour crops, it is impossible to comment on the likelihood ofcurrent and future policies having similar effects. Theobserved changes in hazard reflect the changing politicaland policy environment related to pesticides during the1990s. While it is not possible to point to any single policyinitiative and claim that alone caused the changes, it ispossible to highlight the leading role of EU policy (91/414),and to acknowledge that the debate over pesticide taxesmay have sharpened some minds leading up to theinitiation of the VI. Further, the role of public opinion,the power of consumerism and non-governmental organi-sations cannot be underplayed. All of these factors cametogether during the 1990s to exert pressure on pesticidemanufacturers and users to reduce the risk posed bypesticides. Part of any such risk reduction response willinevitably include a reduction in inherent toxicity, led bythe manufacturing industry, and modifications in use, ledby the agricultural industry.When considering future rationalisation of pesticide

hazard, it could be argued that given the success of theagrochemical industry in reducing the toxicity of theirproducts, they should be expected to do even better in thefuture. Similarly, the agricultural industry has actuallyincreased yields from crops which now offer a lowerpesticide hazard than in 1992, so they must be able to offerfurther reductions in hazard. Conversely, the law ofdiminishing returns would suggest that while furtherreductions in both of these aspects of hazard may bepossible, it is unlikely that such reductions could continueto be achieved year-on-year. So it is currently impossible tospeculate on the likely impact of policy initiatives such asthe VI over the next few years. Indeed, the problem nowfor the VI is to separate its effect from other factors whichare acting to reduce pesticide hazard. If pesticide hazardhas been on a downward trend since at least 1992, thenshould the VI be judged against the pesticide hazard on aparticular date, for example 2002? Or should it only bejudged against the additional reduction in hazard itdelivered above and beyond the background trends inpesticide hazard? Fortunately for proponents of the VI, it isnot required to be judged against pesticide hazard, so manyof these questions are academic. However, they do haverelevance to the design of any future policy initiatives.In conclusion, the results of this work suggest that the

hazard posed by pesticides applied to the most commonlygrown arable crops decreased substantially between 1992and 2002. This long-term trend poses problems whendesigning future policy initiatives, as ideally future policyinitiatives should be assessed against the additional benefitthey provide over and above what would be achieved dueto other factors. Whatever the nature of such policy

ARTICLE IN PRESSP. Cross, G. Edwards-Jones / Crop Protection 25 (2006) 1101–11081108

initiatives, the results of studies such as this could be usedas a baseline against which their achievements could beassessed.

Acknowledgements

Paul Cross is in receipt of an ESRC funded Ph.D.Scholarship. This scholarship is undertaken in associationwith a project funded under the UK Research CouncilsRural Economy and Land Use Programme entitled‘Comparative assessment of environmental, communityand nutritional impacts of consuming fruit and vegetableproduced locally and overseas’ (RES-224-25-0044).

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