Protecting families from contaminated food and water
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Protecting families from contaminated food and water
Posted in Our Blog on June 6, 2025
The amount of mercury in canned tuna is often a deterrent for many people. This low-cost, high protein food is packed with omega-3 fatty acids and many other essential nutrients. Making them a staple in many households.
But experts say to limit this particular food due to the risk of mercury buildup. Because, according to the World Health Organization (WHO), it is one of the ten most harmful chemicals to humans.
A new packaging technology could change this.
Mercury is a metal found in the ocean. While it is a natural element that can generally be found in the environment. It is also a byproduct of manmade pollution.
But that is a topic for another blog post.
Because it is found in the ocean, it makes its way into fish.
Smaller (and younger) fish will have some mercury in their bodies. But the larger amounts of mercury often relate to larger fish. Ones higher in the food chain.
You see, in addition to their own bodies accumulating this toxic metal. Consuming other fish who contain the metal adds up even more over time.
You are what you eat after all…
Tuna isn’t exactly the biggest fish. But it is one of the more commonly consumed fish. In fact, canned tuna may even be the only seafood in some people’s diets. Making mercury in canned tuna something to pay attention to.
Mercury in tuna is a problem because of what mercury does to the brain.
It is a neurotoxin.
It is especially harmful to the developing brain and body of children and the unborn, who are more vulnerable to its effects.
Mercury absorption can lead to learning disabilities and developmental delays in small children. In infants and fetuses, serious consequences such as blindness, cerebral palsy, deafness, and cognitive difficulties are a concern.
In adults, mercury can impact blood pressure regulation and affect fertility.
Other symptoms may include:
Talk to your health care provider if you experience any of these symptoms.
Swedish scientists from Chalmers University of Technology have developed a new packaging technology that can reduce mercury in canned tuna.
“Our study shows that there are alternative approaches to addressing mercury contamination in tuna, rather than just limiting consumption. Our goal is to improve food safety and contribute to enhanced human health, as well as to better utilize food that is currently under certain restrictions,” says Mehdi Abdollahi, Associate Professor at the Department of Life Sciences at Chalmers and coordinator of a project called Detoxpak.
Turns out, a simple amino acid and a concept known as active packaging might be the answer.
Active packaging, when it comes to consumer packaged goods, is not a new concept. Lids that absorb oxygen, desiccate pouches, and other shelf-life enhancing offerings have been available for decades.
When it comes to removing mercury in canned tuna products, at least one other option has been tried. And failed.
In a previous rendition of canning options, one study tried to work with the coating of the package. Thiolated silica was used to help capture mercury from canned fish. But the forces within the tuna tissue did not relinquish the heavy metal.
These Swedish scientists took another look at this problem. According to research, the sulfur-containing amino acids (particularly those with thiol groups) strongly bind and accumulate mercury in tuna fish tissues.
This is what makes them more prone to mercury accumulation in the first place.
These researchers decided to work with this phenomenon.
“By knowing that, we decided to add one of them, cysteine, to a water solution in which fish meat can be immersed. We believed this would allow some of the mercury to be drawn out and instead bind to the solution and be discarded. Further research is needed to take care of the removed mercury,” says Przemysław Strachowski, first author, and at the time of study, a postdoc at the Department of Life Sciences at Chalmers.
They found that this process removed up to 35% of mercury in canned tuna samples.
The greater the surface area of fish flesh that comes in contact with the cysteine solution (much like occurs in water packed minced canned tuna) provided the highest mercury uptake.
There was a limit to how long this activity would work though.
Evidently, after two weeks, no more mercury is removed from the fish. If this method makes it to commercial production, a two week processing time would be needed. But no further.
“The beauty of this type of packaging is that it is active while the product is on the shelf. No additional production steps would be needed if a method like this were used industrially. The application of our results could increase the safety margin for fish consumption,” says Przemysław Strachowski.
Other than discarding the liquid (which most people do anyway), there are no observed changes in canned tuna with this novel packaging.
Researchers also did not indicate changes in smell or appearance. No information on how it tastes was recorded. But that could be due to necessary steps to ensure the product is safe for human consumption. But the report did indicate that cell-based assays have indicated proven safety of the technology.
It could be a while before this type of mercury mitigating technology becomes mainstream.
So. Until then. It is a good idea to continue monitoring the amount of canned tuna you consume in a week.
The U.S. Food and Drug Administration (FDA) recommends children and those who are pregnant, trying to become pregnant, and breastfeeding should opt for fish varieties that are low in mercury.
The amount considered to be a “serving” varies, depending on certain factors.
For example, a serving of canned tuna for an adult is 4 ounces. This is also the serving size for children 11 and older.
For children between one and three years old, this serving drops all the way to 1 ounce.
Children four to seven can consume 2 ounces as a serving and eight to ten is 3 ounces.
When it comes to canned, fresh, or frozen white albacore tuna or yellow fin tuna, a limit of one serving a week is recommended for children and those who are pregnant or breastfeeding.
Light tuna has a slightly lower risk. Current guidelines suggest children should not consume more than two servings a week of light tuna. Those who are pregnant or breastfeeding can consume two to three servings of canned light tuna per week.
New mercury trapping technology could change the way people eat canned tuna. But for now, how concerned are you about mercury in canned tuna with current risks?
Personally, I enjoy a nice cold tuna salad sandwich on a hot summer day. I do pay attention to how often I consume it though.
If you’d like to know more about food safety topics in the news, like “New Packaging Can Reduce Mercury in Canned Tuna By 35%,” check out the Make Food Safe Blog. We regularly update trending topics, foodborne infections in the news, recalls, and more! Stay tuned for quality information to help keep your family safe, while The Lange Law Firm, PLLC strives to Make Food Safe!
By: Heather Van Tassell (contributing writer, non-lawyer)