Fruit and vegetables given to children in schools contain more pesticides than shop-bought produce, a report suggests.
The government research was carried out in 2004
Chemical residues were found in 84% of fresh produce in schools compared with 57% in stores, government figures published by the Soil Association said.
The campaign group said it was "wrong" to provide lower quality food to "the most vulnerable in society".
The government said chemical levels in shops and schools were "broadly similar" but were being monitored.
The government's Pesticides Residue Committee tested 167 items in schools and 882 items of fresh produce on sale in shops last year.
The Soil Association claimed the pesticide levels were higher because the produce supplied by the government's School Fruit and Vegetable Scheme (SFVS) was of a lower quality than those sold in shops.
The association's policy director, Peter Melchett urged the government to increase the use of in-season UK-grown fruit and vegetables and to use more organic produce.
But a spokeswoman for the Department for Environment Food and Rural Affairs said it was "inappropriate" to draw any firm conclusions on residues in school produce because only a relatively small number of items were sampled each term.
In the very few instances, in both school and shop samples, where chemicals in produce were found to be above the maximum residue level, this was by no more than 3%.
"The maximum residue levels are already set well below the safety level," the spokeswoman said.
"None of these would be at a level that would be harmful."
The Department of Health (DoH) said none of the chemical residues gave rise to concerns over children's health.
A DoH spokeswoman said: "Product for the SFVS is sourced from growers whose produce is grown according to the principles of integrated crop management, where pesticide inputs are minimised."
The statistical comparison is included in the Soil Association's Pesticides in School Children's Fruit report.