Activists want tinned tuna banned after toxic levels of mercury found

Consumer advocates warn of ‘colossal risk to public health’ as authorities accused of agreeing to high threshold

Oceans activists are calling for tinned tuna to be banned from hospitals, school canteens, care homes and maternity wards after high concentrations of mercury were found in every sample analysed.

They accused public authorities and the tuna industry of “cynical lobbying”, favouring “the economic interests of industrial tuna fishing to the detriment of the health of over hundreds of millions of tuna consumers in Europe”.

It means that for 50 years a mercury threshold three times higher for tuna than for other fish species such as cod was set as “acceptable”, “without there being the slightest health justification for a different threshold”.

Children and babies are especially vulnerable to high levels of mercury (Getty Images)

French non-profit organisation Bloom, which aims to protect marine environments, and consumer-rights organisation Foodwatch analysed 148 tins of tuna from five European countries: the UK, Germany, Spain, France and Italy.

They found that all the products contained mercury, and 57 per cent exceeded the limit for fish of 0.3mg per kg.

The findings, which they dubbed “a health scandal on an unprecedented scale”, prompted Foodwatch to warn of a “colossal risk to public health”.

Exposure to even small amounts of mercury may cause serious health problems, and threatens development of unborn babies and children, according to the World Health Organisation (WHO), which considers it a major public health concern, on a par with asbestos and arsenic.

Tuna are high up the food chain so accumulate mercury over time (AFP via Getty Images)

Mercury may have toxic effects on the nervous, digestive and immune systems, and on lungs, kidneys, skin and eyes, the WHO says.

Methylmercury, which is what forms after mercury interacts with bacteria and is the most common form in food, is classified as possibly having the potential to cause cancer.

Bloom said: “European public authorities have chosen an approach completely at odds with their duty to protect public health: they use the actual mercury contamination of the tuna to establish a threshold that ensures that 95 per cent can be sold. This is why tuna, one of the most contaminated species, has a maximum mercury tolerance three times higher than that of the least contaminated species.”

Tuna accumulate more mercury over time because they are high up the food chain, eating smaller fish frequently.

But the canning process means that mercury concentration is doubled or tripled, according to Bloom.

It said in the Seychelles, where tuna is caught for Europe, authorities have to carry out only 10 or so tests each year. “Once it lands in France, for example, to our knowledge, fewer than 50 fresh tuna are sampled each year by the public authorities, and no tinned fish is tested.”

Karine Jacquemart, chief executive of Foodwatch France, said: “What we end up with on our dinner plates is a colossal risk to public health that’s not considered seriously.”

Bloom and Foodwatch are calling for a stricter limit of mercury in tuna, the same as for other species, of 0.3mg/kg instead of the current 1mg/kg.

They also are lobbying Europe’s biggest supermarkets to pull products above the threshold from their shelves; a halt to all advertising of tuna products and clear labelling warning of health risks.

And they say tuna products must be banned from hospitals, schools and care homes to protect vulnerable people.

Mark Willis, head of chemical contaminants at the UK’s Food Standards Agency, said: “We advise those who are trying for a baby or who are pregnant to have no more than four cans of tuna a week or no more than two tuna steaks a week. This is because tuna contains higher levels of mercury than other fish.”

The European Commission told Euronews Health the “maximum levels for mercury in food are established on the basis of the data we have on the actual, real-life occurrence of mercury in food”.

“We do this by monitoring products that are placed on the market, taking into account the principle of ‘as low as reasonably achievable’ when producers use good practices,” officials added.

The commission said the maximum level could not be cut below 1ppm “without drastically disturbing food supply”.

“When consuming high amounts of the most polluted fish with the highest maximum levels, the tolerable weekly intake can be exceeded,” it added.

A spokesperson for Europêche, which represents fishing fleets, denied the claims in the report, telling The Independent: “Among the misleading information, the legal threshold communicated is not the one used in practice. In addition, the reported levels were based on dried tuna, instead of raw tuna flesh, resulting in a distortion with a minimum factor of 3.5.

“Scientific studies published in February 2024 by French scientists and Environmental Science & Technology show that mercury levels in tuna have remained unchanged for over 50 years.

“Canned tuna products offered to EU consumers adhere strictly to European regulations, which are based on scientific criteria for safe maximum daily intakes. These thresholds are carefully set by experts from the European Food Safety Authority to ensure consumer safety.”

They added that selenium neutralised the potential toxicity of mercury.

The Federation of Canned Food Industries, which represents the French processing industry, said eating canned tuna was not dangerous and “the products offered to consumers scrupulously respect French and European regulations”. It said tuna was “part of the recommendations for fish consumption as part of a balanced diet”.