Report from the Sub-comittee on the environment and health

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The importance of <strong>the</strong> +scenario for <strong>the</strong> seed pool and plant density Impacts on <strong>the</strong> wild flora in hedgerows and small biotopes The wild flora in natural areas In <strong>the</strong> +scenario, both <strong>the</strong> herbicide dosage and <strong>the</strong> treatment frequency index would probably be somewhat reduced compared with present good farming practice. At <strong>the</strong> same time, increased use of mechanical weed control would partially compensate for <strong>the</strong> reduced effectiveness of <strong>the</strong> chemical control. On average, <strong>the</strong> consequence would probably be, at most, a 10-20% larger total seed pool than in present production. Spray drift of herbicides affects <strong>the</strong> flora in biotopes close to <strong>the</strong> field, such as hedges, field borders and ditches, and along watercourses and ponds. Within a few metres of <strong>the</strong> edges of <strong>the</strong> field, lethal effects can be observed in a number of plant species. The dose and thus <strong>the</strong> effect normally decrease rapidly with distance <strong>from</strong> <strong>the</strong> field, which means that only sub-lethal effects on plant growth and seed production are normally seen outside <strong>the</strong> local zone around <strong>the</strong> field. The magnitude of <strong>the</strong> effect depends on <strong>the</strong> sensitivity of <strong>the</strong> plant species, <strong>the</strong> composition of <strong>the</strong> plant community and <strong>the</strong> condition of <strong>the</strong> vegetation. Several studies have shown effects of spray drift over a distance of up to 50 metres <strong>from</strong> <strong>the</strong> sprayed area (Marrs et al., 1989, 1993; Davis et al., 1993, 1994). However, most of <strong>the</strong> flora were only affected in an area between 0 and 5 m <strong>from</strong> <strong>the</strong> field. However, <strong>the</strong>re is a lack of experimental data on effects of herbicides in low doses on wild plant species, and <strong>the</strong> extent of spray drift and its effect on wild flora have not been systematically studied in Denmark. Both <strong>the</strong> 0-scenario and <strong>the</strong> +scenario would reduce <strong>the</strong> consumption of herbicides and thus <strong>the</strong> risk of spray drift to land close to <strong>the</strong> field. This would considerably reduce <strong>the</strong> load, whe<strong>the</strong>r spraying was discontinued altoge<strong>the</strong>r or was only carried out occasionally. However, owing to <strong>the</strong> lack of data, it is not possible to quantify <strong>the</strong> beneficial effect on <strong>the</strong> vegetation. The areas affected would be reduced in step with <strong>the</strong> herbicide consumption. In <strong>the</strong> 0+scenario, <strong>the</strong> impact would be reduced to <strong>the</strong> few localities in which pesticides were still used. In <strong>the</strong> 0scenario, <strong>the</strong>re would no longer be any impact on <strong>the</strong> neighbouring areas. Besides being affected by herbicides, areas close to <strong>the</strong> field are normally seriously affected by nutrients supplied <strong>from</strong> <strong>the</strong> field, which contribute to a change in <strong>the</strong> composition of <strong>the</strong> flora towards a greater content of grasses and <strong>the</strong> loss of annual and sensitive perennial herbaceous plants. The established, nutrient-demanding vegetation of species of grass and tall perennials, such as creeping thistle, common nettle and cow-parsley, counteracts immigration of o<strong>the</strong>r species. Species with short-lived seeds, such as cornflower, anemone and scabious, often die out, making reestablishment <strong>from</strong> <strong>the</strong> seed pool impossible. All in all, this means that, in many places, a reduced herbicide load on <strong>the</strong> neighbouring areas would not result directly in changes in <strong>the</strong> plant communities in <strong>the</strong> direction of greater diversity unless <strong>the</strong>re were a significantly reduced supply of nutrients and, at <strong>the</strong> same time, physical measures, such as mowing and thinning, which open <strong>the</strong> vegetation to invasion <strong>from</strong> outside or to germination of seeds in <strong>the</strong> seed pool. The diffuse dispersal of herbicides <strong>from</strong> cultivated land must generally be regarded as having little effect on <strong>the</strong> flora in natural areas except where <strong>the</strong>se are directly adjacent to cultivated land. Reduced use of herbicides on cultivated land would <strong>the</strong>refore have little effect on <strong>the</strong> composition of <strong>the</strong> flora, which depends to a far greater extent on <strong>the</strong> management of <strong>the</strong> area and <strong>the</strong> supply of nutrients. There are a few 203
Impacts on <strong>the</strong> flora in forests The pond model 204 research results that indicate a probability of sublethal effects <strong>from</strong> <strong>the</strong> deposition of herbicides <strong>from</strong> <strong>the</strong> atmosphere. One can thus not exclude <strong>the</strong> possibility of damage to sensitive species of flora outside cultivated land as a consequence of herbicides in rainwater. There are very few measurements of <strong>the</strong> occurrence of herbicides in rainwater and in dry depositions in Denmark, and only a few substances have been included in <strong>the</strong> measurements. Fur<strong>the</strong>rmore, <strong>the</strong>re are only a few studies of <strong>the</strong> sensitivity of wild flora and plant communities to sublethal doses of herbicides. In <strong>the</strong> assessment of <strong>the</strong> effects in forests, special definitions have been used, as described in section 10.3.1. If herbicides were no longer used in forests it would in time be possible to recreate a forest-floor flora that was naturally adapted to <strong>the</strong> local soil and climatic conditions. However, mechanical control of undesirable vegetation in <strong>the</strong> form of deep ploughing over large areas could have <strong>the</strong> same direct effects on <strong>the</strong> flora as herbicides and thus also <strong>the</strong> same indirect effects on <strong>the</strong> associated fauna. Besides <strong>the</strong>se, <strong>the</strong>re would be adverse effects on soil fauna, fungal flora, <strong>the</strong> soil profile and historical monuments. Where natural rejuvenation is not used, it is important for <strong>the</strong> forest-floor flora that areas are left untreated and that rejuvenation is in <strong>the</strong> form of shelterwood regeneration with preservation of <strong>the</strong> choice of tree species. The use of herbicides in Christmas tree and ornamental greenery cultures in <strong>the</strong> +scenario and <strong>the</strong> ++scenario would result in continued low biodiversity of <strong>the</strong> flora in <strong>the</strong> areas in question unless alternative, environment-friendly methods were found. 10.3.3 The aquatic environment On <strong>the</strong> basis of data for <strong>the</strong> intrinsic properties with respect to degradability and toxicity, and values <strong>from</strong> <strong>the</strong> literature for run-off and spray drift of pesticides <strong>from</strong> fields to aquatic environments, a dynamic model has been set up for estimating concentrations and effects of pesticides in a model pond that is typical for Denmark. The degree of effect has been estimated with <strong>the</strong> present treatment frequency index and in scenarios with reduced treatment frequency indices and a changed crop distribution. The effects of <strong>the</strong> use of pesticides on flora and fauna in freshwater have been calculated by means of dynamic model built up with <strong>the</strong> simulation tool Stella® (Møhlenberg, Gustavson 1999). No Danish or relevant international data are available for a similar estimation applied to streams and lakes. On <strong>the</strong> basis of existing measurements, Møhlenberg and Gustavson (1999) assume that surface run-off only occurs in events with precipitation of more than 10 mm per day. The variations in <strong>the</strong> precipitation are simulated in <strong>the</strong> model so that <strong>the</strong> events occur at random and, on average, 2-3 times a year. In <strong>the</strong> model, <strong>the</strong> size of <strong>the</strong> pond varies with <strong>the</strong> season, <strong>the</strong> maximum size being reached in March-April (450 m 3 , depth 1.5 m) and <strong>the</strong> minimum size in September (30 m 3 , depth 0.5 m). This variation is typical for Danish ponds and corresponds to <strong>the</strong> surface run-off <strong>from</strong> an area of approx. 2-3 ha. The size determines <strong>the</strong> proportion of a pesticide that is deposited by spray drift and <strong>the</strong> concentration of <strong>the</strong> pesticide in <strong>the</strong> water. The Danish rules on distance to an aquatic environment when spraying with <strong>the</strong> individual pesticides (i.e. 2, 10 and 20 m) are incorporated in <strong>the</strong> model and it is assumed that spraying is not done
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The Bichel Committee 1999 R
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1 INTRODUCTION 7 2 THE SUB-COMMITTE
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9 ENVIRONMENTAL AND HEALTH ASSESSME
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1 Introduction On 15 May 1997 <stro
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The President Members 10 Henrik San
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Consultants’ reports 12 The sub-c
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14 4 Occurrence of pesticides in <s
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The Nationwide Monitoring Programme
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Counties analyse samples fr
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20 system. However, the</st
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941 110 22 MB 270 31 13 MB 1281 10
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Substance Permitte
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26 The distribution of finds of pes
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28 concentrations of up to 11 micro
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Table 4.10 Occurrence of pesticides
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32 It will be seen from</st
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34 • The frequency of detection i
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36 Soil water samples containing pe
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38 Bromoxynil 3 n.d. 0.04 54 DNOC 4
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40 concentrations found so far are
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42 mononitrophenols and oth
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44 The main measure used to try to
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Models for volatilisation 46 • It
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Calculation of the
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Processes that remove pesticides <s
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52 atrazine and the</strong
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Potential sources of pesticides in
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56 Example 1: IPU dosage 1000 g act
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58 completely against future pollut
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Exposure of field fauna through tre
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Leaf beetles Direct effects of spra
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Indirect effects on mammals and bir
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Birds are particularly interesting
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Importance of headland vegetation t
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Effects of pesticides in forestry A
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Repeated spraying changes t
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Effect on seed production The wild
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Impact on the flor
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• The sub-committee recommends mo
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Effects on primary producers The ef
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Effects on amphibians Unlawful use
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concentrations than the</st
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The sub-committee recommends more c
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General ergonomic problems Particul
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Tractor accidents Accidents resulti
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The sprayer operator’s exposure t
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Pesticides and cancer 96 th
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Studies of frequency of cancer Repr
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Neurotoxicity Immunotoxicity and se
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Population studies 102 • Long-ter
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Other risk groups
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106 tomat salat kinakål kartofler
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Calculation of pesticide intake <st
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The Danes’ dietary pattern Reduct
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Estimated intake from</stro
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Table 6.4 Estimated pesticide intak
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Variation in daily intake of pestic
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Endosulfan = Endosulfan Methidathio
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Limit values Authorisation of pesti
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Analytical studies: case control st
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Cancer Mechanism behind the
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Neurotoxicity Neurotoxicity in chil
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128 6.2.7 Conclusions There is insu
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130 • It cannot be proven on <str
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132 Danish products. There are big
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134
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Definition of proportionality Heavy
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Tropospheric ozone Veterinary drugs
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140 effect that can be expected per
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Synthetic pesticid
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144 formulations. Therefore, <stron
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International cooperation 146 be il
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Fuzzy Expert model Expert assessmen
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Setting up a gross list with a view
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Page 169 and 170: Prevention of disease in cereal cro
Page 171 and 172: Prevention of pest attack in agricu
Page 173 and 174: 172 plants whose ability to establi
Page 175 and 176: Biobeds Municipal environmental sup
Page 177 and 178: Malt barley and gushing Direct effe
Page 179 and 180: Effect of soil treatment on wild pl
Page 181 and 182: Emissions of greenhouse gases 180 p
Page 183 and 184: Conclusions concerning environmenta
Page 185 and 186: Conclusions concerning leaching of
Page 187 and 188: 0+-scenario: almost total phase-out
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Page 191 and 192: Soil Residues in the</stron
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Page 195 and 196: Earthworms 194 has been carried out
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Page 199 and 200: Comparison of weed control with and
Page 201 and 202: Results of calculations with <stron
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Page 207 and 208: Results of the mod
Page 209 and 210: Mechanical weed control 208 Behandl
Page 211 and 212: The Dane's dietary pattern and dail
Page 213 and 214: 212 11 The sub-committee’s summar
Page 215 and 216: Conclusion concerning lack of time
Page 217 and 218: Conclusion concerning impacts on fl
Page 219 and 220: Conclusions concerning model analys
Page 221 and 222: Conclusions concerning exposure to
Page 223 and 224: Conclusion concerning mycotoxins Th
Page 225 and 226: Ranking with respect to groundwater
Page 227 and 228: Conclusion concerning emissions of
Page 229 and 230: Conclusions concerning natural subs
Page 231 and 232: 230 12 References Abell, A., Bonde,
Page 233 and 234: 232 Colborn, T., vom Saal., F.S., S
Page 235 and 236: 234 Eyer, P. (1995). Neuropsychopat
Page 237 and 238: 236 Graae, B.J. (1999). Florest flo
Page 239 and 240: 238 Protection Conference: Pesticid
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Page 243 and 244: 242 consumption of fossil energy wi
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Page 247 and 248: 246 Underudvalget for Miljø og Sun
Page 249 and 250: 248 Annex 1 Data required for autho
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Category 1 Category 2 Category 3 25
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256 reasonable and usable system fo
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