Mercury in every can of tuna: this is the alarming discovery made by the NGO BLOOM after analyzing nearly 150 cans from five European countries. Considered by the World Health Organization (WHO) as one of the ten most concerning chemicals for global public health alongside asbestos and arsenic this neurotoxin poses serious risks to human health.

Mercury levels three times higher in tuna

Following an 18-month investigation, BLOOM reveals in an exclusive report how, since the 1970s, public authorities, and the powerful tuna lobby have deliberately prioritized the economic interests of the industrial tuna fishing sector over the health of hundreds of millions of European tuna consumers.

This lobbying has resulted in an « acceptable » mercury limit three times higher for tuna than for other fish species, such as cod, without any health-based rationale for a different threshold. The maximum allowable mercury level in tuna was not set arbitrarily, it aligns with the highest contamination levels in fish. In other words, the danger threshold was set not to protect human health, but solely to protect the financial interests of the tuna industry. These standards, established by public authorities in collusion with the tuna lobby, have led to widespread population exposure to mercury, with potentially serious health consequences.

Mercury : Extremely dangerous poison

Global mercury emissions have risen sharply over the past two centuries, with large quantities now found in the ocean. Mercury accumulates in fish in its most toxic form, methylmercury, eventually reaching the plates of millions of families. As a top predator, tuna accumulates heavy metals from its prey, significantly increasing mercury contamination compared to other fish species.

Tuna is the most consumed fish in Europe. Yet, regular ingestion of methylmercury—even in small amounts, poses serious health risks, particularly to the brain development of fetuses and young children.

100 % of tuna cans tested by BLOOM contain mercury

BLOOM randomly selected 148 canned tuna samples from five European countries (England, Germany, Italy, France, and Spain) and had them tested by an independent laboratory. Every sample was found to contain mercury. More than half of the cans tested (57 %) exceeded the strictest mercury limit set for fish in the European Union (0.3 mg/kg). Among the 148 samples, a can of Petit Navire brand tuna purchased from a Carrefour City store in Paris had a record mercury level of 3.9 mg/kg—13 times higher than the limit for species with the most restrictive cap of 0.3 mg/kg. Given the dangers posed by regular mercury ingestion, even in low doses, all cans exceeding the 0.3 mg/kg threshold should be banned from sale. Unfortunately, this is not the case.

Fake health standards to maximize sales of contaminated products

BLOOM analyzed over a hundred official documents from international health standards organizations (FAO-WHO Joint Committee, European Commission, European Food Safety Authority) regarding mercury. The investigation reveals that no method accounting for the health impacts on adults and children is used to define the maximum mercury content in tuna.

Instead, European public authorities have chosen an approach that blatantly contradicts their duty to protect public health. They use the actual mercury contamination in tuna to set a threshold ensuring that 95 % of it can be sold. This is why tuna, one of the most contaminated species, has a maximum mercury tolerance three times higher than the least contaminated species (1 mg/kg for tuna vs. 0.3 mg/kg for cod, for example). There is no health-based reason for this difference—mercury is not less toxic when ingested through tuna.

Rare and ineffective controls

Contrary to the vigilance such a health concern should demand, almost no monitoring exists throughout the tuna production and distribution chain. In the Seychelles, a crucial hub for tuna fishing for the European market, health authorities are only required to conduct about ten tests. And the situation does not improve once the tuna reaches Europe.

Finally, given that the few existing controls rely on a fixed maximum limit, the number of tests showing non-compliant contamination levels is predictably too low to raise any concern from authorities.

This investigation by BLOOM is part of the « TunaGate » series, which has documented ecological crime and numerous human rights violations attributable to the tuna industry. To put an end to this scandal that exposes hundreds of millions of tuna consumers, BLOOM and Food Watch are mobilizing citizens to demand action from public authorities and major retailers. The two organizations call on public authorities to implement the following urgent measures :

• The European Commission should adopt a conservative threshold for tuna (fresh and canned), aligning it with the strictest limit set for other species: 0.3 mg/kg. Given tuna’s popularity as the most consumed fish in Europe, stricter regulation is justified;
• Member states should invoke safeguard clauses to immediately ban the sale of tuna products with mercury levels above 0.3 mg/kg within their territories;
• Governments and local authorities should protect vulnerable populations by banning tuna products from school cafeterias, nurseries, retirement homes, maternity wards, and hospitals.

Furthermore, BLOOM and foodwatch have launched an international petition targeting ten of the largest European retail chains. The NGOs are urging these supermarket chains to assume their responsibility for consumer health by demanding :

• Rigorous testing and an immediate ban on tuna products with mercury levels above 0.3 mg/kg, rather than the current 1 mg/kg standard;
• An end to all advertising and promotion of tuna products;
• Clear labeling of tuna products, in stores and online, to inform consumers about the health risks associated with mercury contamination.