Endorsing the view that reducing risk is always for the best are the California attorney general and environmental activists. They want to warn consumers about the presence of acrylamide, a known carcinogen, in French fries and potato chips.
Taking a more pragmatic approach are food scientists. They say that acrylamide has been discovered in many foods -- black olives, coffee, bread, breakfast cereal -- and that humans have been eating the chemical for years with few, if any, ill effects.
As the two sides square off, two questions frame their debate: At what level does acrylamide pose a threat to humans? And how much risk is acceptable?
Though acrylamide has long been recognized as a rodent carcinogen and human neurotoxin, no one ever suspected to find it in food. It was believed to be the exclusive product of industrial waste.
Then came the discovery in 2002 that acrylamide is almost everywhere in our diet. The tasteless, invisible byproduct of cooking is formed when foods -- particularly high-carbohydrate foods such as potatoes -- are fried or baked at high temperatures.
Acrylamide turns up in a wide variety of foods; the chemical is present in 40% of our daily calories. But French fries and potato chips contain the highest concentrations, and because Americans consume so much of them, acrylamide fears have focused around these products.
The chemical's sheer ubiquity has led some scientists to question the California attorney general's rationale in filing suit in August against McDonald's, Wendy's, Burger King, KFC and several potato chip manufacturers, including Cape Cod Potato Chips and Kettle Foods.
The suit says the companies are required, under California's Proposition 65, to warn the public that their potato chips and French fries contain a toxic chemical.
Many scientists -- including the author of the only published epidemiological studies on acrylamide -- argue that there simply isn't enough data to justify a warning.
"I think a lot of people were pretty surprised" at the lawsuit, says Lorelei Mucci, a researcher at Harvard University's School of Public Health and lead author of two published epidemiological studies on acrylamide. "It's prevalent in so many foods that to just target these manufacturers is not fair."
Mucci's studies suggest that the amount of acrylamide consumed through diet is insufficient to raise the risk for colon, rectal, kidney, bladder and breast cancers, all cancers caused in high-dose acrylamide testing on laboratory animals.
"More research needs to be done," says Mucci. "But the preliminary evidence is somewhat reassuring."
Other experts, including government scientists, contend that -- with definitive evidence lacking -- California should do what it can to reduce the risk. They emphasize that though acrylamide does exist in a wide variety of foods, its high levels in fries and chips lend special concern.
"We definitely believe acrylamide is a chemical to be concerned about," says George Alexeeff, deputy director for scientific affairs at the state Office of Environmental Health Hazard Assessment, the office that oversees implementation of Proposition 65. "Our general presumption is that unless there's some other evidence, we assume that if something causes cancer in animals, it causes cancer in humans."
The Environmental Protection Agency considers acrylamide potentially so dangerous that it has fixed the safe level for human consumption at almost zero, with a maximum permissible level in drinking water of 0.5 parts per billion.
By comparison, a 2.4-ounce serving of French fries, a small portion at McDonald's, contains about 401 parts per billion, a small, vending-machine-sized bag of potato chips 466 parts per billion.
According to published studies, the average American consumes 40 micrograms of acrylamide a day -- much of it in coffee, a cup of which has 7 parts per billion.
Swedish researchers discovered its presence in food almost by accident while testing workers exposed to acrylamide during railroad construction. When the scientists set up a control group, they were stunned to find high levels across the board.
"They got alarmed, brought it up to the World Health Organization and a series of meetings were convened fairly quickly to look at this issue," says Carl Winter, director of the FoodSafe Program at UC Davis, where he researches naturally occurring toxins in food.
From his viewpoint as a food toxicologist, such fear may not be warranted.
"It's the levels of exposure that determine the risks," he says. "We don't need to take a green light-red light approach to foods. If we eat foods in moderation, we can have very healthy diets."
When it comes to toxicology, the argument goes, the size of the dose makes the poison.
"Dose is the key," says Lois Swirsky Gold, senior scientist and director of the Carcinogenic Potency Project at UC Berkeley, who says that scientists don't yet know that the chemical is hazardous in the doses people get through their diet.
