Almost two thirds of bread products in the UK now contain pesticide residues, according to a report based on Government figures.
The figure has more than doubled from 28% of bread products in 2001 to 63% 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 (PRiF) tested 2,951 bread samples, finding that 61.5% of the non-organic samples over the entire timeframe contained pesticide residues and 17% contained more than one residue.
Some 7% of the organic samples - three out of 42 products tested - contained a single residue, while none contained multiple residues.
Pan UK said the most likely explanation for this was cross-contamination from non-organic crops, either during production or storage.
The average overall figure for pesticide residues in non-organic bread of 61.5% was "much higher" than the overall figure for pesticides residues in all produce combined, which was approximately 40%, Pan UK said.
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", but added that much uncertainty remained and more research was needed.
It said: "Given the situation, 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."
Pan UK spokesman Nick Mole said: "The presence of pesticide residues in our food and our subsequent ingestion of them is not something that anybody should welcome.
"We are in effect being poisoned against our will with the full knowledge of the growers, retailers and regulatory bodies that provide our food or are tasked with making sure it is safe."
The Federation of Bakers said it wanted to reassure consumers that any pesticides on cereals used by UK bakers were approved, regulated and legal.
A spokesman said: "The official Defra expert report, on which the Pan UK report is based, concludes quite clearly that there are no negative impacts on health from any of the residues detected on bread. It is also crucial to acknowledge that all the levels of residue found on bread are considerably lower than the maximum residue limit (MRL), which is an internationally agreed level.
"The interpretation of the report by Pan UK is simply scaremongering consumers into thinking bread is not a healthy food choice. The fact that they are a group whose primary objective is to promote organic products means that they have a vested interest in the messages they are putting across.
"Unlike the Defra expert group, they are not an independent or scientific voice and have given consumers incorrect and misleading advice."
A Defra spokeswoman said: " There is no human health risk from pesticide residues in bread.
"The reported rise in findings is due to our ability to test at lower levels. Levels of pesticide residue in food are minimal and we have strict testing methods in place to check this."