B3. Residues of polychlorinated biphenyls in market basket products and total diets

The use of pesticides in agriculture and horticulture is officially permitted by the Ministries of Agriculture and Public Health. The prescribed rules with respect to the use of pesticides are such that they can be applied efficiently and that, upon harves-ting the edible product, the residues are toxicologically acceptable.

In accordance with the rules of Good Agricultural Practice (GAP) the use of pesticides is therefore only permitted if it yields an effective control of pests and diseases and if the maximum residue limits, which are based on toxicological data, are not exceeded.

In this study it was primarily investigated whether plant-based food commodities and the possible products derived from them are in conformity with the legally fixed maximum residue limits, i.e. whether the amount of residues in these commodities was not too high at the moment of purchase for consumption. In order to do this, a total of 3698 samples covering 21 kinds of vegetables, 15 kinds of fruit and 7 kinds of other commodities were taken over a period of 2 years, 1 April 1991 - 31 March.

On these samples a variety of analyses were performed, using both multi-residue methods, in which several pesticides are detected in one analysis, as well as specific methods, in which only one kind of pesticide is detected. For the whole of the re-search project twelve analytical methods were available and about 130 different pestici-des or metabolites could be detected. On the basis of information concerning both the use of pesticides and the detected residues, those analytical methods were applied that enable the detection of pesticides which are applied to a given crop in normal circumstances, and which could be expected to result in residues.

The percentages of exceeded maximum residue limits detected with the help of these analyses are as follows:

	Percentage of samples not conforming with the MRLs	Percentage of samples with residues without MRLs	Total percentage of non-conforming samples
Vegetables	6.9	2.5	9.4
Fruit	0.7	1.4	2.1
Other	1.2	0.0	1.2
Total	4.2	1.8	6.0

The samples that did not conform with the legal maximum residue limits mainly concern leafy vegetables of which the whole plant is harvested and in which residues of all applied pesticides may therefore be present. For that reason, the risk of excee-ding the tolerance limit is obviously greater than in the case of e.g. tomatoes or apples, where most of the pesticides are applied with the purpose of keeping the plant healthy and a proportionally smaller amount of pesticide ends up in the final harvested product, resulting in lower amounts of residues.

The samples with residues for which no maximum residue limits exists, are the result of using non-permitted products (therefore no residue tolerances are available, but the products may well be allowed in e.g. neighbouring countries) or the presence of residues in crops that are not grown in Belgium (grapes, oranges, bananas) but of which the use of pesticides is legally permitted in countries of production.

The secondary aim of the present study was to determine the amount of pesticides that is taken up through consumption. In order to do this each commodity in which residues could be detected in the first analysis was processed in the way that it is normally processed before consumption (washing, peeling, boiling, etc ...). Afterwards a new analysis was performed and in some cases a second or third culinary treatment was performed, each time with a subsequent new analysis.

In this way it was possible to gain an insight in the decrease in residue after normal culinary processing, which is clearly of importance to the consumer as a way of limiting the intake of pesticides through consumption. In Table 10 examples are given of the percentages with which the residues decreased after the above mentioned culinary processes.

In order to calculate the intake of pesticides, the amount of detected residues in the con-sumption-ready commodity was recalculated to values per 100 g of commodity and expressed as percentages of the ADI value. This is the toxicologically acceptable daily intake by a person of 60 kgs as determined by the World Health Organisation (WHO) and the World Food and Agriculture Organisation (FAO).

In order to determine the average intake of pesticides by means of the investigated food commodities it is necessary to know how much of each of these commodities is on average consumed daily per person. Since no official figures are available for this in Belgium an estimated survey was made on the basis of information on buying habits supplied by the National Institute of Statistics (NIS) and the Agricultural Econo-mic Institute (LEI).

Next, a choice was made from the most obvious culinary processes that each commo-dity is subjected to, e.g. washing for lettuce, peeling for carrots. In some cases no processing was taken into consideration e.g. in the case of apples (no peeling after purchase). For each detected pesticide the percentage of the ADI was calculated that is taken up through the average amount of each food commodity per day.

Finally, the total percentage of the ADI was calculated for each pesticide in the whole food package under investigation.

Overall, in the most average situation, with a daily intake of the investigated food package, the following results were obtained:

• a total of 54 different pesticides are taken up
• the percentages of the ADI of only two pesticides are higher than 1% i.e. dithiocarbamates (1.9%) and bromide (1.6%).

As a general conclusion of this study it can be said that:

• the maximum residue limits are exceeded fairly in vegetables, more particularly in leafy vegetables available to the Belgian consumer and produced in Belgium but also in other countries as no distinction was made between domestic and imported food
• the processing of vegetables and fruit before consumption (e.g. peeling, washing, boiling) results in a significant reduction of the amounts of residue taken up
• the real uptake of pesticides through consumption is much lower than what may be considered toxicologically acceptable

Two remarks are in order here:

1. If a comparable study was made in other countries, the percentage of exceeded maximum residue limits might be lower than in Belgium. It should be clearly stated in this respect that the results of a residue investigation are largely dependent on the number of different analytical methods used. Usually only multi-residue methods are applied while specific methods are used to a much lower degree, which is in contrast to what was done in the present study (e.g. the anti-spouting agent chlor-propham used on potatoes, and bromides on leafy vegetables).

2. Because of the ultimate limitations on the available financial means and the analytical equipment and methods at our disposal, not all food commodities were investigated in this study and therefore it cannot be claimed that all conceivably present pesticides were detected.

All the results of this study have been collected as shown in great detail in 4 appendices which are available on diskette.

The titles of these appendices are: