Proposition 65 was introduced in 1986 and requires manufacturers to give clear warning if their product exposes an individual in California to any detectable amount of more than 800 listed chemicals and chemical families known to the state to cause cancer or reproductive toxicity.
However Stephanie Sheridan of Sedgewick Detert Moran & Arnold LLP, Swanson's attorneys, said that nearly all foods and dietary supplements contain detectable levels of one or more of the 800 listed chemicals, since these chemicals occur naturally in the environment and cannot be removed.
Moreover, the proposition does not differentiate between substances beneficial to life, those that are chemically inert in the body, and those that are hazardous.
Under the Federal Food, Drug and Cosmetic Act (FFDCA), the FDA has the authority to establish food safety standards, good manufacturing practices, and to regulate food labelling.
This, according to the attorneys, means that there is a conflict of law between since food and supplement makers cannot comply both with the FFDCA restrictions on misleading statements and obligations under and the obligations under Proposition 65 to put warnings on all products with a detectable level of a listed chemical.
The North Dakota company has therefore asked the FDA to issue a directive finding acknowledging this conflict, and initiate a full evaluation to give all parties a chance to have their voices heard.
This is said to be the first such citizen petition to bring up the conflict pre-emption issue with respect to foods and dietary supplements.
"Proposition 65, when applied to foods and dietary supplements, causes consumer confusion because it misbrands wholesome products and frustrates FDA's ability to carry out its statutory mandates," said Sheridan.
She added that it compels alarmist warnings at negligible levels, "diluting the importance of FDA advisories regarding real hazards."
Swanson' quality control/compliance manager Kari Graber said: "We need one standard, and that standard should be set at federal level."
Another result of the claimed conflict is that Proposition 65 encourages private enforcement actions against food and supplement makers - said by the attorneys to be "bounty-hunter tactics".
"In the view of many, Proposition 65 permits legalized extortion of the business community by private enforcers, who retain 25 per cent of civil penalty as well as all attorneys fees and costs," said Carol Brophy, also of Sedgwick Detert Moran & Arnold.
She says that thousands of businesses have been forced into settlements, since the costs of mounting a defence are prohibitive.
In some cases, companies have been sued more than once for the same products.
No indication has been given as to whether Swanson has been targeted by such private enforcement actions.
The FDA had not responded to a request for FDA's position on the matter, or what the likely next steps are likely to be.