Citation: Environmental Research (2004) in press.
Mercury in Canned Tuna: White versus Light and Temporal Variation

SUMMARY

Canned tuna is the most commonly consumed form of fish in the United States. We conducted a survey of total mercury levels in canned tuna over a period of five years 1998 to 2003. We analyzed individual cans of solid white and chunk white tuna (Albacore; n=123 cans) and light and chunk light tuna (mainly Skipjack Tuna; n=45) cans. Analyses were performed in the Elemental Analysis Laboratory of the Environmental and Occupational Health Sciences Institute, Piscataway, New Jersey under a rigorous quality assurance protocol, which included confirmatory analyses at two independent laboratories. White tuna averaged 0.407 ug/g (parts per million on a wet weight basis) of total mercury, compared with 0.118 parts per million for light tuna. These results are similar to the FDA's 1991 study published by Norma Yess in 1993. The maximum total mercury level in the present study was 0.997 ppm but 25% of white tuna samples exceeded 0.5 ppm, which FDA had originally established as its action level. Data suggest a slight increase in levels since 1991, and mercury levels were significantly higher in 2001 than in other years. Based on a separate analysis, at least 89% of the mercury can be considered methylmercury. The FDA lists a value of 0.17 ppm as an average for canned tuna, but this is not appropriate information for people who have a consistent preference for Albacore. There were no significant differences in mercury levels in tuna packed in oil compared to water. Draining contents had no effect on mercury levels, and the fluid, both oil and water, contained little mercury. These data indicate that people who eat canned tuna frequently can choose light tuna and reduce their mercury intake. Since cans of white tuna frequently exceed the FDA's original action level of 0.5 ppm, it would be prudent to continue some systematic monitoring of the Nation's canned fish supply, particularly as the targets of commercial fisheries inevitably change as certain stocks become depleted.

Fish provide a healthful source of dietary protein, and are relatively low in cholesterol and high in omega-3 (n-3) fatty acids. As the nation has become more health conscious, many people have increased their fish intake. We suggest that future advisories include data on canned tuna that distinguishes white from light and allows consumers to make informed choices.

May be cited as Burger and Gochfeld. ENVIRONMENTAL RESEARCH "in press" (2004)