Researchers from the University of Nevada, Las Vegas tested more than 300 samples of canned tuna. They found more than half had mercury levels higher than the EPA standard.
There was also a significant difference in mercury concentration by type of tuna.
Albacore tuna had the highest concentrations of mercury when compared to light tuna.
Mercury poisoning can damage the central nervous system and cause hearing and vision loss.
The study appears in the February issue of Environmental Toxicology and Chemistry.