Report from the Sub-comittee on the environment and health

see above) or as an element of a restrictive treatment practice with
specific requirements concerning time limits for spraying seed-bearing,
berry-bearing and fruit-bearing crops etc.
With respect to <strong>the</strong> rules on pesticide residues in groundwater and
drinking water, <strong>the</strong>re is a distinct difference between <strong>the</strong> health
assessment of <strong>the</strong> limit value and <strong>the</strong> environmental importance of <strong>the</strong>
limit value, as also illustrated in figure 8.1 above. Whereas, with respect
to human toxicology, all known pesticides have up to <strong>the</strong> present time
been found acceptable/tolerable with respect to <strong>the</strong> groundwater criterion
of 0.1 microgramme per litre, <strong>the</strong> figure with two concentration effect
curves exemplifies how <strong>the</strong> lethal effect level for aquatic organisms
(measured as EC50 or LV50) can be exceeded at values below 0.1
microgramme per litre. There are several such examples, particularly
among insecticides, and for an environmental point of view, <strong>the</strong> value 0.1
microgramme per litre is in this case not an expression of <strong>the</strong>
precautionary principle of <strong>the</strong> zero value approach. A risk assessment of
<strong>the</strong>se individual substances on <strong>the</strong> basis of existing laboratory data would
lead to a lower limit value than 0.1 microgramme per litre for aquatic
organisms.
It should also be noted that limit values set on <strong>the</strong> basis of detection
limits are not static quantities. For example, technological development,
with growing use of detection by means of mass spectrometry, means
that it is now possible to determine <strong>the</strong> occurrence of a number of
substances down to detection levels of 0.005 microgramme (µg) per litre,
i.e. concentrations up to 20 times lower than was technically possible in
1980, when <strong>the</strong> limit value of 0.1 microgramme per litre was set.
There are thus no technical obstacles to reducing <strong>the</strong> guideline limit
value of pesticide residues in drinking water, and one could, in principle,
continue reducing it in step with <strong>the</strong> development of analytical methods.
This would mean that, as a consequence of <strong>the</strong> zero value approach’s
precautionary principle, one would not only move away <strong>from</strong> <strong>the</strong>
precautionary principles of <strong>the</strong> effect assessment/risk management
approach, but would also, in some years’ time, approach a limit value
that very few pesticides could meet.
Continued reduction of <strong>the</strong> limit values in step with <strong>the</strong> development of
methods of analysis would thus ultimately mean banning all use of
pesticides if one maintained that one would not accept measurable
quantities.
8.2.3 The sub-committee’s conclusions and recommendations
Two different approaches to <strong>the</strong> precautionary principle can be used –
here called <strong>the</strong> risk assessment approach and <strong>the</strong> zero value approach.
Use of <strong>the</strong> risk assessment approach can imply a “conservative” (=
“cautious”) assessment based on concrete, empirical evidence, whereas
use of <strong>the</strong> zero value approach can be based on an initially valuedetermined
quality requirement that is only deviated <strong>from</strong> after
assessment based on definable protection requirements.
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