Mercury in Tuna: Understanding Risks, Levels, & Solutions

Recent Concerns About Mercury in Tuna

Recent findings by the BLOOM Association on mercury contamination in canned tuna have attracted media and public attention. According to their study published on October 29, 2024, 57% of the samples tested in five European countries exceeded the safety limit of 0.3 mg/kg​.​

These results underline the importance of scientific and regulatory measures to better understand mercury-related risks and protect consumers.

What Is Mercury Contamination?

Mercury is a naturally occurring metal released into the environment through natural processes and human activities. Once released, mercury undergoes complex transformations and cycles between the atmosphere, oceans, and land. It exists in three main chemical forms:

• Elemental or metallic mercury (Hg⁰),
• Inorganic mercury (mercurous (Hg₂²⁺) and mercuric (Hg²⁺) cations),
• Organic mercury, with methylmercury being the most common form in the food chain.

Methylmercury, the most toxic form, accumulates in fish and seafood, posing serious health risks, particularly to:

• Pregnant women,
• Children,
• Women of childbearing age.

This compound has been classified by the International Agency for Research on Cancer (IARC) as a possible human carcinogen (Group 2B), especially for kidney cancer. Moreover, the World Health Organization (WHO) identifies mercury as one of the top ten chemical threats to global public health.

Mercury in Tuna: How High Are the Levels?

The accumulation of mercury in fish varies by species. Tuna, being a predatory fish, typically contains higher levels of methylmercury due to bioaccumulation. Studies show that levels can vary:

• Light tuna (e.g., skipjack): Lower levels of mercury, making it a safer choice.
• Albacore and yellowfin tuna: Often contain higher mercury levels, especially in canned varieties.

According to EU Regulation (EU) 2023/915, the maximum allowable mercury levels are:

• 0.3 mg/kg for lower-risk fish such as cod, herring, and salmon.
• 1 mg/kg for high-risk fish like tuna, swordfish, and marlin.
• 0.5 mg/kg for other species not listed under categories 3.3.1.2 and 3.3.1.3 of the regulation.

Health Risks of Mercury in Tuna

Methylmercury primarily targets the nervous system, posing the greatest risks to developing brains in unborn children and infants. Symptoms of mercury poisoning include:

• Impaired cognitive and motor functions,
• Neurological damage,
• Increased risks of certain cancers (e.g., kidney cancer).

How to Safely Consume Tuna

The EFSA recommends limiting the consumption of tuna for vulnerable groups:

• Pregnant women should avoid high-mercury species like albacore and yellowfin.
• Opt for light tuna (skipjack) for reduced mercury exposure.

Mérieux NutriSciences: Ensuring Food Safety

Mérieux NutriSciences offers reliable, cutting-edge solutions to address mercury contamination in food. Our services include:

• Advanced chemical analyses to accurately measure mercury and other heavy metals, ensuring compliance with regulatory standards.
• Regulatory guidance to help food producers navigate complex legislation and ensure safety.

By partnering with us, you can confidently manage contamination risks and meet consumer safety expectations.