Report from the Sub-comittee on the environment and health

Knowledge-building in <strong>the</strong>
groundwater field
Need for knowledge in <strong>the</strong>
groundwater field
Terrestrial ecosystems
Aquatic ecosystems
Human health
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existing indices differed in <strong>the</strong>ir structure, leading to different indexing
of pesticides. Within <strong>the</strong> EU, a Concerted Action (CAPER) has
commenced. The object is to compare <strong>the</strong> usefulness of eight different
indicators.
• In <strong>the</strong> years ahead, research programmes now in progress will add to
our knowledge concerning <strong>the</strong> fundamental problems, and
improvements that are being made in <strong>the</strong> monitoring of groundwater
and early warning of <strong>the</strong> risk of leaching of pesticides to <strong>the</strong>
groundwater will increase <strong>the</strong> safety level.
• The sub-committee wishes to point out that improved risk assessment
depends on continued clarification of <strong>the</strong> processes governing <strong>the</strong>
transport of pesticides to <strong>the</strong> groundwater and in <strong>the</strong> groundwater
aquifers and on greater understanding of <strong>the</strong> spatial variation in <strong>the</strong>
parameters governing <strong>the</strong> transport of pesticides. As results come in
<strong>from</strong> an ever-growing number of both national and international
studies, decision-making tools should be developed on <strong>the</strong> basis of
statistically documented relationships for pesticides’ potential
leaching with a view to generalising <strong>the</strong> studies to uninvestigated
areas and pesticides. In connection with increased use of
ma<strong>the</strong>matical models (e.g. MACRO) in <strong>the</strong> assessment of <strong>the</strong> risk of
pesticide leaching, <strong>the</strong> sub-committee recommends that work
continue on assessing <strong>the</strong>ir validity. In this connection, <strong>the</strong>re is a
particular need for geological and substance-specific data. The
possibility of developing simple stochastic (probabilistic) models
should be investigated.
• With respect to <strong>the</strong> terrestrial environment, it is not possible to
indicate a method for ranking <strong>the</strong> direct effects, because <strong>the</strong> indirect
effects and <strong>the</strong> combination of many pesticides play <strong>the</strong> biggest role.
However, <strong>the</strong> treatment frequency index can be used as a measure of
<strong>the</strong> impact because it is based on <strong>the</strong> biologically active field dosage
and can thus be used as a simple indicator of both <strong>the</strong> direct effect on
<strong>the</strong> target organisms and related species and for <strong>the</strong> indirect impact on
<strong>the</strong> ecosystem as a consequence of changes in quantity and type of
food in <strong>the</strong> food chains. It would also be possible to calculate an index
for <strong>the</strong> dosage believed, with our present level of knowledge, to be
harmless to most animals and plants in uncultivated areas that receive
pesticides via spray drift or atmospheric transport (tolerable limits).
• For <strong>the</strong> aquatic environment, <strong>the</strong> present authorisation scheme
includes an expert assessment that can result in new pesticides or
products being authorised on condition that a given distance is
maintained to watercourses and lakes. Such distance requirements
indicate that <strong>the</strong> substance (<strong>the</strong> product) is problematical in relation to
aquatic organisms and could be directly used for ranking or
classifying <strong>the</strong> pesticides.
• For <strong>the</strong> human-toxicological area one could use <strong>the</strong> relationship
between <strong>the</strong> Acceptable Daily Intake, ADI, and <strong>the</strong> estimated
exposure to <strong>the</strong> substance as a basis for ranking pesticides. In
Denmark, with <strong>the</strong> present use of pesticides, <strong>the</strong> exposure at single
substance level through food products is around 1% or less. Ranking