Relatively high percentages of violations were found in leafy vegetables. One exception to this is iceberg lettuce, in which less than 1 percent of the samples contained an excessively high level.
Lettuce and spinach
For leafy vegetables from other countries, an average of one in five products do not comply with the Dutch regulation. Oxadixyl was commonly found in iceberg lettuce from Spain. Chlorothalonil and tolclofos-methyl are found quite frequently in Dutch endives. These are both pesticides used to combat fungi. While pesticides based on these compounds may be used in diverse types of fruit and vegetables, neither substance has been certified for use on endives in the Netherlands.
Tolclofos-methyl has been authorised for use in lettuce. A concentration above the limit was found in only a single case in lettuce, but the picture of the violations in this vegetable is ambiguous. Various other chemicals were also found. In Dutch spinach iprodione is quite often found. Once again this is a chemical that has been authorised for use in other crops, but not in spinach.
The various types of cabbage seldom contain high levels of pesticides. In most varieties of cabbages there are no traces of pesticides at all. The exception here is Chinese cabbage, in which 3.8 percent of the products tested were found to exceed a limit.
Tomatoes, peppers and
Tomatoes, peppers and cucumbers are important Dutch export products, so it is hardly surprising that these products are sampled regularly. One striking result is the high percentage of products (75 percent) in which no traces of pesticides whatsoever are found. In Dutch peppers and cucumbers, infringements of the limits were found in an average of 2.4 percent of the samples. For products from other countries this percentage is very high, at 20 percent.
The products concerned come mainly from Spain. In Spanish cucumbers the substances oxadixyl and metalaxyl are found quite frequently. Metalaxyl is a fungicide that may be used in strawberries, but is not certified in the Netherlands for cucumbers. In Spanish peppers the compound methamidophos is found quite frequently. In the Netherlands pesticides based on this compound may not be used in growing peppers, but they are permitted for potato crops.
Apples, pears, plums and strawberries
In the various varieties of apples, pears and plums the rates of violations found are low. In strawberries the proportion is 3.3 percent, which is considerably lower than the percentage of violations in strawberries from other countries. The origin of strawberries from other countries is very diverse, as are the sorts of pesticide that are found. In Dutch strawberries it is mainly bupirimate that is found. This chemical may be used in crops such as apples, strawberries, cucumbers and tomatoes.
One likely cause for the violations is that the waiting time between spraying and the harvest, which has been set for strawberries at three days, has not been complied with.
Samples have also been taken of imports of the same products to the Netherlands, but the number of samples is often so small that no comparison can be made. High percentages of violations, especially of the substances heptenofos, tolclofos-methyl and chlorothalonil were found in excessive concentrations in celery and bleach celery. Here again, the cabbage varieties stand out in a favourable sense.
As a result of previous KAP reports and other developments there have been public and commercial discussions, and debates in the policy-making sphere, in relation to the trend in the residues found in a number of products. Now that the KAP has been in operation for five years, it is possible to draw up graphs of these trends showing whether this discussion and the resulting measures have had any effect.
The rate of violations in imported products has increased markedly. In 1996 and 1997 many violations were reported for lettuce, pepper and strawberry. Many of these violations relate to the authorisation policy, which is organised at a national level. The fact that the Dutch authorisation policy has been tightened by the Board for the Authorisation of Pesticides, and is reflected in the Dutch regulation on residues, will not have an immediate effect on the day-to-day practice of farmers in other countries. They naturally look first at their own national regulation.
Average violation rate
The average violation rate for Dutch fruit and vegetables is between 1 and 2 percent. There is no sign of a trend. As for products from other countries, there does on average seem to be an increase in the number of products tested that do not comply with the Dutch regulation, especially in the period 1995 to 1997. There may however be some bias in this picture.
Although an allowance has been made for the volume of each type of product that is imported when determining the total rate of violations for imported products, it is likely that more knowledge has been collected in the course of time about the probability of violations in products coming from different regions. This effect has not been allowed for in the weighted average.
In presenting the total residue balance for Dutch fruit and vegetables it would be preferable to use results from a representative random sample. But to achieve the most effective detection or monitoring one needs to select the more suspect products. If there is no externally observable difference within a product type that is related to the probability of finding a violation, and the probability of a violation during the course of the year is constant, the average presented here is representative for that product.
A representative average for the whole group of fruit and vegetables is obtained by linking the average probability of a violation for each product to the quantity of that product that is consumed. In practice the probability of a violation will not remain constant during the year. However there are too few observations per month or per season to correct this bias by weighting. The results presented in figure 2.5 for Dutch products would very probably be a fraction lower if the sampling was truly random.
The same is true for imported products. In this case there is a bias because products originating from particular countries of origin in particular seasons are sampled more frequently than would be the case using random sampling.