In 2004, the US Food and Drug Administration issued a statement warning women and children to limit their consumption of certain varieties of canned tuna with exceptionally high mercury levels. Fresh fish was not included in the warning; however, recent evidence suggests that fresh tuna, like that used in sushi, may contain even higher levels of the dangerous metallic element. After testing sushi purchased at restaurants throughout New York City, researchers found that a mere 6 pieces of tuna sushi contain more mercury than health officials recommend a person consume in an entire week.