Are there heavy metals in canned tuna? A look at the science and safety

November 7, 2025 •

4 min read

Recent studies have indicated that while some canned tuna products contain detectable levels of heavy metals like mercury, these concentrations are often within regulatory limits and are generally considered safe for consumption. However, varying levels and sources of contamination mean that understanding the risks is crucial for making informed dietary choices.

Quick Summary

This article explores the presence of heavy metals, particularly mercury, lead, and cadmium, in canned tuna. It examines the sources of contamination, differences between tuna types, health risks associated with certain heavy metals, and regulatory standards to help consumers assess potential risks.

Key Points

Low to Moderate Levels: Most canned tuna contains low levels of heavy metals like mercury, often within safety guidelines set by organizations like the FDA and WHO.
Tuna Type Matters: Canned light tuna (skipjack) typically has lower mercury levels than canned albacore or fresh tuna, which are larger, older fish.
Bioaccumulation is Key: Tuna are predatory fish high on the food chain, which explains why they accumulate higher levels of mercury than smaller fish.
Health Recommendations: For most, the health benefits of eating tuna in moderation outweigh the risks, but vulnerable groups like pregnant women and young children should follow specific guidelines to limit intake.
Risk Mitigation: Varying protein sources and choosing smaller fish species, like skipjack, can help minimize heavy metal exposure.
Safety Monitoring: Regulatory bodies and producers conduct regular testing to ensure heavy metal levels remain within safe limits, though some localized issues can occur.

Understanding Heavy Metals and Bioaccumulation in Tuna

Heavy metals, such as mercury (Hg), lead (Pb), and cadmium (Cd), are naturally occurring elements that can become concentrated in the environment through industrial pollution and other factors. In marine ecosystems, a process called bioaccumulation occurs, where these metals accumulate in living organisms over time, and a related process, biomagnification, causes concentrations to increase as the metals move up the food chain.

Tuna are predatory fish and sit high on the marine food chain. They consume smaller fish that have already accumulated small amounts of heavy metals. This results in larger, older tuna having higher concentrations of mercury, primarily in the form of highly toxic methylmercury, than smaller, younger fish. This is the primary reason for concern over mercury levels in tuna.

Sources of Heavy Metal Contamination

There are several sources of heavy metal contamination in canned tuna, with most coming from the fish itself, but some from the canning process:

Environmental Pollution: Industrial waste, agricultural runoff, and the burning of fossil fuels release heavy metals into waterways, where they enter the food chain.
Fish Size and Species: As mentioned, larger species of tuna, like albacore, accumulate more mercury than smaller species, like skipjack or light tuna.
Processing and Packaging: While less common today, historical studies have shown that heavy metal contamination can occur during processing, or from the materials used in the canning process, such as soldering. Regular monitoring is recommended to control for this.

Mercury Levels in Different Tuna Types

When considering mercury, it's essential to differentiate between the types of tuna. The U.S. Food and Drug Administration (FDA) provides guidance on this difference. Here is a general comparison:


Tuna Type	Common Species	Heavy Metal Content	Recommended Consumption	Reason for Difference
Canned Light Tuna	Skipjack	Lower mercury levels	More frequent consumption is generally considered safe, following national health guidelines.	Skipjack are smaller, younger fish and accumulate less mercury during their lifespan.
Canned Albacore Tuna	Albacore	Higher mercury levels	Less frequent consumption, especially for sensitive groups like pregnant women and children.	Albacore are larger, predatory fish and bioaccumulate more mercury over a longer lifespan.
Fresh/Frozen Tuna	Various	Varies significantly	Consumption should be limited and managed, especially for larger species like Yellowfin.	Levels depend heavily on the specific species, size, and origin of the fish.

Health Risks and Regulatory Standards

While trace amounts of heavy metals are common in many foods, the potential health risks emerge from consistent, high-level exposure over time. For example, high levels of methylmercury exposure can cause neurological issues, and even developmental problems in children. Lead and cadmium can also cause adverse health effects on the kidneys and other organs.

Regulatory bodies worldwide, such as the World Health Organization (WHO), the Food and Agriculture Organization (FAO), and national agencies like the FDA, have established permissible limits for heavy metals in food.

Research from multiple regions, including the Persian Gulf and the Mediterranean coast of Libya, found heavy metal concentrations in canned tuna were generally well below permissible levels, suggesting the products were safe for consumption.
However, some studies show instances where mercury levels in certain canned tuna samples have exceeded the limits of specific national or regional regulations, indicating that monitoring is important. A 2019 study in Mexico found a few samples with mercury concentrations above the Mexican limit, while some lead and cadmium levels exceeded stricter EU standards.
A 2023 study on canned fish in Turkey found that while estimated weekly intake levels generally didn't pose a risk, some tuna samples had high target hazard quotients for certain metals, particularly arsenic, potentially posing risks for children if consumed heavily.

Tips for Consumers

For most people, the nutritional benefits of moderate seafood consumption outweigh the risks posed by heavy metals. Canned tuna is a valuable source of protein and omega-3 fatty acids. However, certain precautions can help minimize exposure, especially for vulnerable populations.

Here are some actionable tips for incorporating canned tuna into a safe and healthy diet:

Choose canned light tuna (typically skipjack) over canned albacore or fresh tuna, as it contains significantly less mercury.
Vary your sources of protein and omega-3s. Don't rely exclusively on tuna, but incorporate other low-mercury fish like salmon, cod, and sardines.
Consider the consumption recommendations from health authorities. The FDA and EPA provide guidelines, particularly for pregnant women, breastfeeding mothers, and young children, who are more susceptible to mercury's effects. You can find detailed advice on the FDA's official website.
Pay attention to sourcing. Some producers offer mercury-tested products or provide information on their sourcing methods, ensuring they use younger or smaller fish.

Conclusion

Ultimately, the question of whether there are heavy metals in canned tuna is best answered with a nuanced understanding of the facts. While the presence of trace heavy metals, including mercury, is a reality due to environmental factors and bioaccumulation, the concentrations in most canned tuna products on the market are low and well within regulatory safety limits. For the average, healthy adult, moderate consumption of canned tuna, particularly lower-mercury light varieties, is a nutritious and low-risk option. Consumers can further minimize their risk by varying their diet and following consumption advisories from health authorities. Regular testing and monitoring by regulatory bodies and food producers help ensure the continued safety of canned tuna products for everyone.

Frequently Asked Questions

Canned light tuna, typically made from skipjack, generally has the lowest mercury levels. It comes from smaller, younger fish that have had less time to accumulate the heavy metal.

Yes, but with limitations. Health authorities, including the FDA, advise pregnant women to limit their consumption of certain types of tuna to minimize mercury exposure. Canned light tuna is the safer choice over albacore.

Heavy metals enter tuna primarily through bioaccumulation in the marine food chain. Tuna, as apex predators, accumulate metals from smaller fish they eat. Environmental pollution is a key contributor to the presence of these metals in the ocean.

Yes, other heavy metals such as lead, cadmium, and arsenic can be present, though studies often show they are within permissible limits in most products.

Historical issues with packaging materials, particularly certain soldering techniques, have been noted, but modern regulations and industry practices have significantly reduced this risk. It is not the primary source of heavy metal contamination.

To choose a safer option, select canned light tuna (skipjack) from a reputable brand that follows regulatory guidelines. You can also vary your seafood intake to avoid over-reliance on a single source of protein.

Yes, regulatory bodies like the FDA and food producers conduct regular testing and monitoring to ensure that heavy metal levels in canned tuna and other seafood do not exceed safety standards.

Bioaccumulation is the buildup of a substance, such as a heavy metal, in an individual organism over time. Biomagnification is the increasing concentration of a substance as it moves up the food chain, from smaller organisms to larger predators like tuna.