The figure has more than doubled from 28 per cent of bread products in 2001 to 63 per cent last year, the study by Pesticide Action Network (Pan) UK and the Organic. Naturally Different campaign found.
Between 2000 and 2013, the Defra Expert Committee on Pesticide Residues in Food tested 2,951 bread samples, finding that 61.5 per cent of the non-organic samples over the entire timeframe contained pesticide residues and 17 per cent contained more than one residue.
Some seven per cent of the organic samples contained a single residue, while none contained multiple residues. Pan UK said the most likely explanation for this was cross-contamination.
The report said studies had shown that even very low doses of certain pesticides ingested regularly and in combination with other chemicals could have "unforeseen effects".
It said: "It seems like common sense to avoid or at least limit consumption where possible. At the very least, we believe consumers should have the right to make informed choices about their food."