Tin levels in UK canned foods are lower than five years ago and are well within regulatory limits, according to a UK Food Standards Agency (FSA) survey released last week.
Of the 400 different samples of canned fruit and vegetables and tomato-based products tested, 99.5 per cent contained tin concentrations below 200 milligrams per kilogram (mg/kg) - the maximum legal amount of tin that can be present in canned foods.
The FSA reports that relatively high levels of tin were found in some samples when canned fruit and vegetable products were last surveyed in 1997, and tomato products in 1999.
In the latest survey only two products were found to contain levels of tin above the legal limit: one sample of gooseberries and one of spaghetti in tomato sauce.
Manufacturers and suppliers voluntarily withdrew these affected batches from store shelves after the Agency notified them. They also issued notices in stores and the national press asking consumers to return the products.
Most foods, adds the FSA, contain very low concentrations of tin. Canned foods may contain higher levels because the tin coating used to protect the steel body of the can from corrosion can slowly transfer into food.
No long-term health effects are, as yet, associated with consuming tin - but it can cause stomach upsets such as nausea, vomiting, diarrhoea, abdominal cramps and bloating in some sensitive people at levels above 200 milligrams per kilogram.
According to the FSA most of our dietary intake of tin (94 per cent) comes from canned fruit and vegetables.
The FSA is working with the food industry and enforcement officials to find out the causes of tin contamination in canned foods and to minimise the likelihood of high levels. It is of no surprise to learn that the survey confirms that introducing cans that are fully lacquered on the inside to contain acidic foods has helped to control and reduce tin levels.
The 200 milligram per kilogram limit is supported by the Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT). This committee gives the FSA, as well as other government departments, expert advice on chemical safety in food.