LOS ANGELES — Cereals manufactured by General Mills, Inc., Kellogg Co. and Post Foods L.L.C. do not need to display cancer and reproductive harm warnings because they contain acrylamide under California’s Proposition 65, according to the Court of Appeal of the State of California, Second Appellate District.

In a July 16 ruling, the court determined that a private lawsuit brought forward by Richard Sowinski, a retired physician, was pre-empted by letters submitted by the U.S. Food and Drug Administration to California health officials. The F.D.A.’s letters stressed the importance of encouraging whole grain consumption, of which many of the cereals targeted in the suit are considered a good source of. Several of the cereals also contain lipids and folic acid, which qualify for health claims.

Dr. Sowinski’s complaint alleged that 59 breakfast cereals manufactured by the cereal companies and sold in California contain acrylamide, and therefore are required to include cancer and reproductive toxicity warnings. He alleged that failure to include such warnings violated the Safe Drinking Water and Toxic Enforcement Act that Proposition 65 enacted.

In their defense, the cereal manufacturers cited the F.D.A.’s ongoing efforts to provide consumers with scientifically-based risk information. The manufacturers said warning labels would only add to confusion for consumers.

“Petitioners contend such warnings on cereals are preempted by federal law because they would pose an obstacle to federal policy objectives to increase Americans’ consumption of whole grains,” the cereal manufacturers noted in the July 16 filing. “In support, Petitioners cite to numerous federal statutes establishing that policy, and Food and Drug Administration letters to California regulators cautioning against Proposition 65 warnings on cereals because they could mislead consumers and cause them to avoid whole grains, resulting in health detriments.”

Associate Justice Victoria Gerrard Chaney wrote in the July 16 letter that the F.D.A.’s policy, described in its advisory letters to California’s regulators and Attorney General, is that no Proposition 65 warning for acrylamide should be placed on foods, including breakfast cereals, unless and until the science supports such a warning.

“Even then, the F.D.A. may, as it does with trans fats, require producers to identify foods that contain acrylamide and the amount, and educate the public about the risks and benefits of various types of breakfast cereals based on quantities consumed,” Ms. Chaney said.