Report from the Sub-comittee on the environment and health

Calculation of pesticide
intake <strong>from</strong> food products
and drinking water on <strong>the</strong>
Danish market
Methods of calculation
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pears, grapes and strawberries, which account for most of <strong>the</strong> load.
However, <strong>the</strong> sum of <strong>the</strong>se substances covers pesticide residues with very
different toxicological properties, so <strong>the</strong> substances are not directly
comparable and <strong>the</strong>ir combined action is not known. The Ministry of
Food, Agriculture and Fisheries has initiated a study that will throw light
on <strong>the</strong>se questions within some years. Ano<strong>the</strong>r important factor in
connection with <strong>the</strong> summation of <strong>the</strong> pesticide residues in food products
is that it does not include reduction factors. Some of <strong>the</strong> pesticide
residues are removed during preparation - for example, peeling of
oranges, mandarins, etc., <strong>the</strong> peel of which is seldom used. However,
<strong>the</strong>re are as yet insufficient data to clarify <strong>the</strong> size of <strong>the</strong> reduction factors
in Danish diet. This aspect will also be looked at in a new study initiated
by <strong>the</strong> Ministry of Food, Agriculture and Fisheries. A closer comparison
of <strong>the</strong> individual food products and <strong>the</strong>ir significance for <strong>the</strong> intake of
pesticides, and thus <strong>the</strong>ir possible toxic effects, is difficult for several
reasons, including <strong>the</strong> fact that <strong>the</strong> data are often too limited, but also
because <strong>the</strong> individual pesticides have different toxicological properties.
It must be mentioned, however, that <strong>the</strong> higher detection rate in imported
crops reflects <strong>the</strong> fact that, for comparable crops, <strong>the</strong>re tend to be fewer
positive results in Danish products than in imported ones. This tendency
is most pronounced for crops like tomatoes, cucumber and peppers,
which are greenhouse crops in Denmark but outdoor crops in o<strong>the</strong>r
countries. However, <strong>the</strong> tendency does not apply to all crops. There are
also examples, e.g. blackcurrants, where pesticide residues are more
frequent in Danish crops than in imported ones.
The following calculation of <strong>the</strong> Danes’ intake of pesticides through <strong>the</strong>ir
diet is based on monitoring data <strong>from</strong> <strong>the</strong> Danish Veterinary & Food
Administration’s national monitoring programme in 1996 and 1997
(Büchert 1998). These data are not only <strong>the</strong> latest data but were also
obtained with comparable methods and reporting limits. It is
characteristic that no content was detected in most of <strong>the</strong> samples tested.
Regardless of this, it must be assumed that treated crops always have a
certain residual content, so that lack of detection can only be taken to
mean that <strong>the</strong> content, if any, is below <strong>the</strong> analytical detection limit.
Different models can be used to calculate <strong>the</strong> pesticide intake <strong>from</strong> crops
in which no residual content has been detected. In situations in which
<strong>the</strong>re are sufficient data above <strong>the</strong> detection limit, <strong>the</strong> distribution under
<strong>the</strong> detection limit can be determined with reasonable statistical
certainty. Unfortunately, that is not <strong>the</strong> case with <strong>the</strong> available
monitoring data. The residual content in samples without a detected
content must <strong>the</strong>refore be expressed in a different way – for example, by
putting <strong>the</strong> pesticide content at 0 (zero) or, conversely, by assuming that
it corresponds to <strong>the</strong> detection limit. However, both are ra<strong>the</strong>r rough
approximations.
In this connection it must be stressed that <strong>the</strong> analytical detection limit is
not a fixed quantity. It varies <strong>from</strong> one pesticide to ano<strong>the</strong>r and <strong>from</strong> crop
to crop, just as <strong>the</strong>re is a variation <strong>from</strong> one analysis to ano<strong>the</strong>r of <strong>the</strong>
same substance in <strong>the</strong> same crop. However, since <strong>the</strong> exact data are not
directly accessible, <strong>the</strong> calculations are based on <strong>the</strong> more general
detection limits, which are determined for <strong>the</strong> individual substances
during <strong>the</strong> validation of <strong>the</strong> methods. The residual concentration in