Report from the Sub-comittee on the environment and health

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to <strong>the</strong> soil and plant surfaces, <strong>the</strong> humidity of <strong>the</strong> soil, atmospheric turbulence, and <strong>the</strong> concentration of <strong>the</strong> pesticide, including its degradation, also play an important part. It is possible to calculate <strong>the</strong> volatilisation <strong>from</strong> ground surfaces by means of simple ma<strong>the</strong>matical models, whereas <strong>the</strong>re are as yet no similar models for calculating <strong>the</strong> volatilisation <strong>from</strong> plant surfaces. According to model calculations, <strong>the</strong>re can be considerable volatilisation <strong>from</strong> ground surfaces – <strong>the</strong>oretically right up to 100% within a few days in <strong>the</strong> case of some substances. In <strong>the</strong> Ne<strong>the</strong>rlands it is estimated that about 20% of <strong>the</strong> total amount placed of all types of pesticides evaporates. Model calculations show that very little of most of <strong>the</strong> pesticides used in Denmark is transported <strong>from</strong> ground surfaces to <strong>the</strong> atmosphere through volatilisation, although some substances show a big potential for volatilisation. The following specific conclusions can be drawn: • Calculations indicate that, quantitatively, considerable volatilisation of <strong>the</strong> substances fenpropimorph, pendimethalin, permethrin, propyzamide, prosulfocarb and trifluralin can occur. There is thus a risk of <strong>the</strong>se substances being spread in <strong>the</strong> atmosphere and detected in rainwater and surface water. The fate and occurrence of <strong>the</strong>se substances in <strong>the</strong> atmosphere over Denmark have not been investigated. • There is a need for studies of <strong>the</strong> actual volatilisation of <strong>the</strong> pesticides used in Denmark with a view to later modelling of <strong>the</strong> volatilisation. • In order to be able to estimate <strong>the</strong> importance of atmospheric deposition of pesticides in Denmark in relation to o<strong>the</strong>r sources, knowledge is needed about <strong>the</strong> rate of removal <strong>from</strong> <strong>the</strong> atmosphere through dry and wet deposition. • Knowledge is lacking about <strong>the</strong> fate of pesticides in <strong>the</strong> atmosphere – particularly <strong>the</strong>ir degradation, <strong>the</strong> rate of degradation and possible formation of environmentally xenobiotic reaction products. 4.6.7 Degradation and leaching of pesticides Pesticides degrade in a stepwise process, often via <strong>the</strong> formation of metabolites, <strong>the</strong> chemical structure of which may be similar to <strong>the</strong> original pesticide. A pesticide’s metabolites can be more toxic and leach more easily than <strong>the</strong> original pesticides. This applies, for example, to <strong>the</strong> atrazine metabolites, deethylatrazine and desisopropylatrazine. It is <strong>the</strong>refore of great importance that studies of <strong>the</strong> persistence of pesticides in <strong>the</strong> soil and leaching <strong>from</strong> <strong>the</strong> soil include corresponding studies of metabolites (Fomsgaard 1998). Degradation and sorption are key factors in <strong>the</strong> assessment of pesticides’ persistence in <strong>the</strong> soil. The time of application and <strong>the</strong> locality also affect <strong>the</strong> persistence of pesticides. The amount of organic matter in <strong>the</strong> soil can lead to greater sorption and thus slower degradation and slower leaching. Conversely, <strong>the</strong> organic matter can also increase <strong>the</strong> presence of microorganisms, which can in turn increase <strong>the</strong> rate of degradation. 49
Processes that remove pesticides <strong>from</strong> <strong>the</strong> soil Persistent pesticides Persistence analyses in <strong>the</strong> authorisation of pesticides 50 Extreme soil environments, such as <strong>the</strong> surface on railway lines, paths and car parks, are such poor environments for biological activity that herbicides used on <strong>the</strong>se areas are degraded very slowly. Fur<strong>the</strong>rmore since <strong>the</strong>se types of soil bind pesticides poorly, <strong>the</strong>y have a high potential for pollution of groundwater. A wide range of processes – surface run-off, volatilisation, uptake in plants, leaching and degradation – help to remove pesticide residues <strong>from</strong> <strong>the</strong> soil after spraying. Degradation and metabolism in plants differ <strong>from</strong> <strong>the</strong> o<strong>the</strong>r processes by transforming <strong>the</strong> substance or removing it permanently <strong>from</strong> <strong>the</strong> environment. Surface run-off and leaching can carry <strong>the</strong> substance into surface water or groundwater; volatilisation can lead to <strong>the</strong> occurrence of pesticide residues in rainwater; and uptake by plants can lead to contaminated food if <strong>the</strong> pesticide is not broken down after uptake. Pesticide residues can also be bound in <strong>the</strong> soil without being degraded. Pesticides are generally ei<strong>the</strong>r degraded abiotically, e.g. by photodegradation, or biologically, primarily through biological conversion by microorganisms. A persistent pesticide is characterised by remaining intact in its active form if it is not sensitive to physical and chemical factors or if <strong>the</strong> microorganisms cannot degrade it. In addition, metabolites, degradation products or reaction products that can be similarly persistent can be formed. The pesticide and/or <strong>the</strong>se metabolites can be inaccessible to degradation if <strong>the</strong>y are adsorbed on humus or clay minerals. The distribution of pesticides between <strong>the</strong> soil’s pore water and particles of soil is an equilibrium between free molecules and molecules bound to ei<strong>the</strong>r dissolved organic matter or to attached soil particles. There is <strong>the</strong>refore a possibility that pesticides bound in <strong>the</strong> soil can later be released as a consequence of a change in <strong>the</strong> physical-chemical environment, e.g. acidification of <strong>the</strong> soil or degradation of humus or clay minerals. In connection with <strong>the</strong> authorisation of pesticides, laboratory tests are carried out as a basis for assessing <strong>the</strong> persistence. The active ingredient or its metabolites, degradation products or reaction products that are of environmental importance must not have a half-life of more than 3 months and not more than 10% of <strong>the</strong> amount applied must remain after one year. If only a small proportion of <strong>the</strong> active ingredient (i.e. less than 5% in 100 days) is completely broken down into CO2, water and salts, <strong>the</strong>re is a risk of it being bound unchanged in <strong>the</strong> soil. It is <strong>the</strong>refore a requirement that not more than 50% of <strong>the</strong> active ingredient may be bound in <strong>the</strong> soil after 30 days or max. 70% after 100 days. If <strong>the</strong>se values are exceeded, an evaluation of <strong>the</strong> conditions for use is carried out and relevant field trials may also be included in <strong>the</strong> assessment. Active ingredients that have half-lives of more than 6 months and that imply a risk of exposure of <strong>the</strong> external environment are regarded as possessing unacceptable persistence. This means that <strong>the</strong> pesticide in question cannot be authorised. In cases in which relatively large amounts of a persistent pesticide are bound in <strong>the</strong> soil after repeated application without being directly accessible, it is known that small amounts of <strong>the</strong> pesticide can be absorbed by plants, earthworms and microorganisms. With continuous
Page 1: The Bichel Committee 1999 R
Page 4 and 5: 1 INTRODUCTION 7 2 THE SUB-COMMITTE
Page 6 and 7: 9 ENVIRONMENTAL AND HEALTH ASSESSME
Page 8: 1 Introduction On 15 May 1997 <stro
Page 11 and 12: The President Members 10 Henrik San
Page 13 and 14: Consultants’ reports 12 The sub-c
Page 15 and 16: 14 4 Occurrence of pesticides in <s
Page 17 and 18: The Nationwide Monitoring Programme
Page 19 and 20: Counties analyse samples fr
Page 21 and 22: 20 system. However, the</st
Page 23 and 24: 941 110 22 MB 270 31 13 MB 1281 10
Page 25 and 26: Substance Permitte
Page 27 and 28: 26 The distribution of finds of pes
Page 29 and 30: 28 concentrations of up to 11 micro
Page 31 and 32: Table 4.10 Occurrence of pesticides
Page 33 and 34: 32 It will be seen from</st
Page 35 and 36: 34 • The frequency of detection i
Page 37 and 38: 36 Soil water samples containing pe
Page 39 and 40: 38 Bromoxynil 3 n.d. 0.04 54 DNOC 4
Page 41 and 42: 40 concentrations found so far are
Page 43 and 44: 42 mononitrophenols and oth
Page 45 and 46: 44 The main measure used to try to
Page 47 and 48: Models for volatilisation 46 • It
Page 49: Calculation of the
Page 53 and 54: 52 atrazine and the</strong
Page 55 and 56: Potential sources of pesticides in
Page 57 and 58: 56 Example 1: IPU dosage 1000 g act
Page 59: 58 completely against future pollut
Page 62 and 63: Exposure of field fauna through tre
Page 64 and 65: Leaf beetles Direct effects of spra
Page 66 and 67: Indirect effects on mammals and bir
Page 68 and 69: Birds are particularly interesting
Page 70 and 71: Importance of headland vegetation t
Page 72 and 73: Effects of pesticides in forestry A
Page 74 and 75: Repeated spraying changes t
Page 76 and 77: Effect on seed production The wild
Page 78 and 79: Impact on the flor
Page 80 and 81: • The sub-committee recommends mo
Page 82 and 83: Effects on primary producers The ef
Page 84 and 85: Effects on amphibians Unlawful use
Page 86 and 87: concentrations than the</st
Page 88: The sub-committee recommends more c
Page 91 and 92: General ergonomic problems Particul
Page 93 and 94: Tractor accidents Accidents resulti
Page 95 and 96: The sprayer operator’s exposure t
Page 97 and 98: Pesticides and cancer 96 th
Page 99 and 100: 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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Better monitoring of the</s
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154 help in the as
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Impact index for the</stron
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Knowledge-building in the</
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160 In relation to the</str
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Uncertainties and variations 162 A
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164 which is fixed at 0.1 microgram
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166 If the risk as
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Prevention of disease in cereal cro
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Prevention of pest attack in agricu
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172 plants whose ability to establi
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Biobeds Municipal environmental sup
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Malt barley and gushing Direct effe
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Effect of soil treatment on wild pl
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Emissions of greenhouse gases 180 p
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Conclusions concerning environmenta
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Conclusions concerning leaching of
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0+-scenario: almost total phase-out
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Scenarios for forests Weath
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Soil Residues in the</stron
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Impact on the fiel
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Earthworms 194 has been carried out
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Assumptions and uncertainties Resul
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Comparison of weed control with and
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Results of calculations with <stron
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202 Scenarier Ingen behandling Plus
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Impacts on the flo
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Results of the mod
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Mechanical weed control 208 Behandl
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The Dane's dietary pattern and dail
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212 11 The sub-committee’s summar
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Conclusion concerning lack of time
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Conclusion concerning impacts on fl
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Conclusions concerning model analys
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Conclusions concerning exposure to
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Conclusion concerning mycotoxins Th
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Ranking with respect to groundwater
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Conclusion concerning emissions of
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Conclusions concerning natural subs
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230 12 References Abell, A., Bonde,
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232 Colborn, T., vom Saal., F.S., S
Page 235 and 236:
234 Eyer, P. (1995). Neuropsychopat
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236 Graae, B.J. (1999). Florest flo
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238 Protection Conference: Pesticid
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240 Lindhardt, B., Sørensen, P.B.,
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242 consumption of fossil energy wi
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244 intoxication. The Pesticide Hea
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246 Underudvalget for Miljø og Sun
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248 Annex 1 Data required for autho
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250 11) Metabolism in animals The s
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252 Annex 2 The general rules for r
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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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