Tuna mercury contamination greater than suspected
Mercury levels in tuna could be higher than previously thought, according to a study of the popular fish conducted by an American pressure group.
But now developments in the US, where evidence has emerged that eating too much tuna can lead to learning difficulties in children, have led to calls for action on this side of the Atlantic.
US pressure group the Mercury Policy Project tested a sample of white albacore tuna and found levels of the heavy metal were significantly higher than in other tuna species and that 5% of tins analysed were so contaminated they should have been recalled as unfit for human consumption.
The project's Michael Bender said the tests confirmed what the US regulator, the Food and Drugs Administration (FDA), had known since the 1990s.
"Yet because FDA halted testing of canned tuna for mercury in 1998 to save money and because industry keeps its results secret, parents are unknowingly exposing their children to mercury," he said.
"Our sample size was admittedly small," said Bender. "We chose 60 cans of tuna randomly off grocery shelves (but) there is no reason to believe that these results are not reflective of what millions of people consume."
Methylmercury- the organic form mercury assumes in fish- is a potent neurotoxin that poses the greatest risk to the developing foetus, infants, and young children.
It is common in most fish, but is usually found in higher concentrations in larger predatory fish as their diet is already contaminated.
The FSA currently issues advice that pregnant women do not eat shark, marlin or swordfish.
But a spokesman for the agency told edie it had no plans to change its advice on tuna consumption.
"The FSA's advice is that there does not need to be an upper limit for tinned tuna for children," she said.
This is based on international guidelines from the World Health Organisation and advice from the independent expert committee of scientists who last looked at this issue in March 2004."
She said it was important that children eat a healthy balanced diet, including a variety of foods to help ensure they obtain the wide range of nutrients they need.
The albacore is a commercially sought-after migratory fish and the only tuna species which can be marketed as 'white tuna meat', bringing a premium price at the dock and in the tin.
It is more common in the US than in the UK, where the more commonly consumed tuna species are skipjack and yellowfin.
By Sam Bond