Some food packaging contains hidden latex that could trigger potentially fatal allergic reactions, a study has revealed.
Latex can be found in rubber bands
The investigation commissioned by the Food Standards Agency (FSA) found that, in some cases, the rubber proteins were transferred to food.
The findings, reported in Chemistry and Industry magazine, have prompted calls for changes in food labelling.
However, the FSA said it was too early to draw firm conclusions.
A statement from the food watchdog said: "The Food Standards Agency advises consumers not to change what they eat or how they prepare it, as it is not clear that there actually is transfer of allergens from latex to food outside the laboratory."
Latex, derived from natural rubber, is used in food packaging materials such as rubber bands, stickers on fruit and vegetables and in cold-seal adhesives for confectionery.
Between 1-6% of Britons are thought to suffer from latex allergies.
Although there are no agreements on safe levels of latex, as little as a billionth of a gram per millilitre (1ng/ml) has been reported to cause a reaction.
Ice cream wrappers
Scientists at Leatherhead Food International measured latex allergen levels in 21 types of food packaging.
They found a third of the materials contained latex; the highest level was found in an ice cream wrapper, which measured allergen levels at more than 370 ng/ml.
And in three cases they discovered latex allergens had transferred to the food. One chocolate biscuit contained about 17 ng/ml of latex allergen.
An advisory panel for the UK Latex Allergy Support Group (LASG) called for changes to food labelling rules.
Graham Lowe, a consultant dermatologist in Dundee and representative for LASG, said: "For a few people, natural rubber latex is a very potent allergen and for these individuals, there is no safe level of exposure.
"We would welcome an approach to the EU to consider this evidence and the issue of labelling."
However, the Food Standards Agency said more research was needed before any firm conclusions could be drawn.
A spokesperson for the FSA said "Advisory labelling should only be used when, following a thorough risk assessment, there is a real risk of allergic reactions."