Residues of pesticides and preservatives were detected in 82 out of 91 samples - 90 per cent - of imported sweet oranges, and four out of seven samples of home-produced blackcurrants, the ministry disclosed yesterday.
Checks at ports have led recently to one consignment of Turkish oranges being refused entry. Sampling of blackcurrants will be increased this year because of children's high consumption of blackcurrant drinks.
Five pesticides were found in the blackcurrants and 20 pesticides and preservatives in the oranges, imported from countries such as Argentina, Morocco, Cyprus and Israel. However, none of the blackcurrant samples and only four of the orange samples exceeded the maximum residue level, which is one measure of the risk they pose.
Many of the orange-exporting countries have relatively lax controls on pesticide use. However, ministry officials denied yesterday that the liberalisation of trade under the new Gatt (General Agreement on Tariffs and Trade) regime was likely to lead to more contaminated products entering the UK.
Dr Peter Stanley, chairman of the working party on pesticide residues, said fruit and vegetables were already imported from 42 countries. 'I am not sure that Gatt will change that very much,' he said.
According to the working party's annual report for 1992, 71 per cent of 3,177 samples tested were pesticide-free; 29 per cent contained residues; and 1 per cent were above maximum residue levels - figures similar to the previous year.
The report cites evidence of banned pesticides being used on British winter lettuces and an increase, for the second year, of 'extremely low' levels of lindane - used in wood treatment and head-lice shampoos - in milk.Reuse content