Consumer Reports finds ‘unpredictable’ mercury spikes in canned tuna

An investigation by Consumer Reports on Thursday morning found “unpredictable” mercury spikes in five popular brands of canned tuna — and suggests pregnant people are “avoiding canned tuna altogether.”

“While canned tuna, particularly light varieties, have relatively low average mercury levels, individual cans can sometimes have much higher levels,” according to Consumer Reports.

“From can to can, mercury levels can rise in unpredictable ways, which could endanger a fetus’ health,” said James Rogers, director of food safety research and testing at Consumer Reports.

The mercury levels found in consumer reports were within FDA standards, which say pregnant women can eat canned tuna in limited amounts.

CBS News reached out to all five companies in the report. Chicken of the Sea, Safe Catch, StarKist and Wild Planet said their products are safe and meet FDA standards. Bumble Bee didn’t get in touch with us early Thursday morning, but did note to Consumer Reports that “the health benefits of eating seafood far outweigh any potential risk, including concerns about mercury.”

Mercury is a neurotoxin — a compound that affects neurodevelopment, said CBS News medical associate Dr. David Agus. Potential health risks from mercury include impaired brain function, loss of smell and developmental delays in children.

If a developing fetus is exposed to high levels of mercury, cognitive problems could arise later in life, Agus said.

“Young children and pregnant women in particular need to keep mercury away from developing neurons,” he said.

Consumer Reports tested 10 products, including albacore and light tuna, from each of the five tuna brands. A total of 30 samples – all tuna products packaged in water – were tested.

Lighter tuna generally contain less mercury than albacore, which comes from larger fish. “But you can’t tell how much mercury a given can contains,” said Michael Hansen, senior scientist at Consumer Reports.

Consumer Reports said that of the 30 samples tested, six individual peaks in mercury levels were found — equivalent to one in five cans — “that would change the FDA’s recommendation of how often someone should eat that particular tuna.”

“What this report has shown is that while light contains much less mercury than other tuna, it is variable and you will get a batch with a higher level here and there,” Agus said.

According to Consumer Reports, the tests provide insight into what consumers “may experience at any given moment when eating these brands of tuna and underscore the importance of making safer choices in their daily routines.”

“One key takeaway is that albacore tuna, regardless of brand, contains much more mercury than light tuna or skipjack tuna,” Consumer Reports said. “That’s not surprising since albacore tuna are larger and live longer than the tuna that make up light tuna or skipjack tuna. But the differences were quite large: the albacore tuna products contained, on average, three times as much mercury as the others.”

Mercury cannot be removed by boiling. It is an impurity in charcoal; When coal is burned, elemental mercury rises into the clouds and comes down when it rains, ending up in the ocean as methylmercury, Agus explained. Marine animals absorb the pollutant.

“Fish eat it, and then big fish eat the smaller fish, and that’s how they accumulate mercury,” Agus said.

Fish with higher levels of mercury include sharks and swordfish. Very little mercury is found in smaller surface fish, such as trout and salmon, Agus noted.

Consumer Reports suggests that adults who aren’t pregnant aim for 8 to 12 ounces of fish per week, which is relatively low in mercury.

“This could hold up to three batches of light or skipjack tuna. …You can eat albacore tuna, but only a four-ounce serving per week,” says Consumer Reports.

It suggests that kids stick to light or skipjack tuna and eat low-mercury fish in limited amounts.

Editor’s note: This story has been updated to correct a line comparing lighter tuna to albacore tuna. Light tuna generally have less mercury than albacore tuna.

Trending News