"Bagged salads are more likely to be contaminated in your own kitchen, where there are other raw and cooked foodstuffs present, than in a processing line where they go through a strictly controlled process to ensure that they are safe," he told Grower.
Last month, the Health Protection Agency (HPA), which is now part of Public Health England, said an investigation into an outbreak of Cryptosporidium infection, which caused stomach upsets but no fatalities in England and Scotland, "showed strong evidence of an association with pre-cut bagged salad products likely to have been labelled as 'ready-to-eat'".
However, the agency was unable to identify the specific source of the contamination, with the conclusion being drawn on the basis of statistical correlations.
The head of the HPA's Outbreak Control Team Dr Stephen Morton said: "This outbreak was fortunately short-lived but it was important to see if we could find the source. Our findings suggest that eating mixed-leaf bagged salad was the most likely cause of illness.
"It is, however, often difficult to identify the source of short-lived outbreaks of this type as by the time the outbreak can be investigated, the affected food and much of the microbiological evidence may no longer be available."
Fresh Produce Consortium chief executive Nigel Jenney said: "This is an extremely rare association of Cryptosporidium with fresh produce in the UK. Consumers should continue to enjoy eating fresh produce as part of a healthy diet."
He added: "It's common sense for consumers to follow good hygiene practices in the home when preparing any food."