Food residue analysis

The annual UK report on pesticide residues in food shows that 30% of 3,700 samples analysed contained detectable residues. About 1% of samples were above the maximum residue level (MRL)1. Results for over 83,000 pesticide/commodity combinations were reported by the government's Working Party on Pesticide Residues (WPPR). WPPR's programme covers dietary staples, rolling programmes on the main food groups, surveys on overall human dietary exposure, and ad hoc targeted surveys.
    Dietary staples-bread, potatoes and milk-are sampled regularly. Ironically only 9% of samples of highly processed white bread contained pesticides while for organic bread the figure was 18%-the latter are thought to be a result of fraud. Lindane (or gamma-HCH) was found at low levels in 30% of milk samples, up from 26% in 1993 and down from 65% in 1992. Pesticides were detected in 43% of potato samples and one exceeded the MRL, with the highly toxic insecticide aldicarb found at a concentration of 2.3 mg/kg, five times over the estimated acceptable daily intake (ADI) health limit of 0.003 mg/kg body weight. This level could induce 'mild transient symptoms' such as a upset stomach in a sensitive individual, according to Dr. Peter Stanley WPPR's Chair.

Prosecutions over lettuce?
For several years WPPR has highlighted misuse of pesticides by a minority of UK lettuce growers (see PN 26, p. 20). In an enforcement programme between November 1994 and February 1995, 48 samples were analysed for two prohibited fungicides vinclozolin and chlorothalonil. As a result, five cases are under investigation. Details have been withheld until after the legal proceedings.

DDT in wood pigeons
Analysis has revealed that 53% of UK wood pigeons sampled contained detectable residues of DDT. In one sample, 0.5 mg/kg were found which exceeds the MRL by five times. This indicates that DDT, banned in 1984, is still being used illegally.

Chinese rabbit refused
Surveillance and enforcement monitoring has revealed continuing problems with Chinese rabbit meat. Many samples contain levels of the highly persistent beta-HCH. By the end of 1994, three samples from 32 consignments were found to contain excessive levels and were refused entry into the UK.

Quality industry data required
The food industry relies widely for pesticide residues and releases some data for publication by the WPPR. The latest batch includes 955 samples from a range of commodities. Whilst welcoming these initial steps the WPPR report  questions the validity of some of the data referring to it as 'semi-quantitative', which means that its overall reliability could not be judged.

Annual report of the Working Party on Pesticide Residues: 1994, Ministry of Agriculture Fisheries and Food & Health and Safety Executive, 1995, HMSO, London, £27, 146pp.

[This article first appeared in Pesticides News No. 30, December 1995, page 15]