Does All Tuna Have Mercury or Just Canned?
                                
                                
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                                    5 min read                                
                            
                                According to the U.S. Food and Drug Administration (FDA), nearly all fish and shellfish contain traces of methylmercury, meaning it is inaccurate to assume only canned products carry this risk. The key difference in mercury exposure from tuna, whether fresh or canned, lies in the species and size of the fish, which directly correlates to the level of bioaccumulation.