California Appellate Court Decision: No Warnings For Canned Tuna -- Methylmercury is Naturally Occurring

Date: Mar 16, 2009

The California Attorney General filed a lawsuit in 2004 against Tri-Union Seafoods, Del Monte and Bumble Bee Seafoods, seeking Proposition 65 warnings on canned and packaged tuna products containing mercury and mercury compounds, which are listed as carcinogens and reproductive toxins. In 2006, San Francisco Superior Court Judge Robert Dondero ruled, in People v. Tri-Union Seafoods, that the Proposition 65 warning requirement did not apply to mercury in canned tuna.

The trial court decision was based on three alternative grounds. First, the trial court gave "substantial deference" to FDA's position (as stated in an August 2005 letter from former FDA Commissioner Lester Crawford to then-Attorney General Bill Lockyer) that the proposed warnings were preempted by the Federal Food, Drug and Cosmetic Act due to conflict with the federal policy to provide information about the risks and benefits of eating canned tuna through advisories. Judge Dondero wrote that warnings for a healthy product that the federal government encourages people to eat would be misleading, and that tuna canners could not comply with both federal and state law without rendering their products misbranded under federal law.

The trial court also disagreed with the Attorney General on scientific issues. Under Proposition 65, there is an exemption from the warning requirement for a listed chemical that is naturally occurring in food (Title 27, Cal. Code of Regs., section 25501). A chemical is naturally occurring if it is a natural constituent of a food or is present in a food solely as a result of absorption or accumulation of the chemical which is naturally present in the environment in which the food is raised, or grown, or obtained, and only to the extent that it did not result from any known human activity. Judge Dondero concluded that most methylmercury in canned tuna occurs naturally in the ocean, and interpreted the naturally occurring exemption as covering chemicals in food that are the result of both natural and uncontrollable human activity. And finally, the trial court found that the human epidemiologic studies used by the Attorney General were insufficient to support the State's maximum allowable dose level (MADL) for reproductive toxins. The tuna canners had relied on a 1993 draft MADL from California's Office of Environmental Health Hazard Assessment (OEHHA), based on animal studies. The trial court accepted the draft MADL and the tuna canners' potential exposure estimate (which was below the draft MADL).

The State appealed the trial court ruling on all grounds, and the Court of Appeal, First Appellate District, issued an opinion on March 11. The court affirmed the trial court judgment on the ground that methylmercury in tuna is naturally occurring and therefore not subject to Proposition 65. The opinion did not rule on the two other grounds for the trial court decision, but was based solely on a finding of "substantial evidence" supporting the trial court's decision, the applicable standard of review. Importantly, the court noted that within "the broader naturally occurring issue, we further declined to review the trial court's decision interpreting the pertinent regulation as including within the 'naturally occurring' rubric those chemicals in food that are the result of both natural and uncontrollable human activity." Thus, while this decision is a victory for the tuna industry, it does not provide further guidance on the scope of the naturally occurring exemption.