"The epidemiology doesn't show anything, and even if you ignored the epidemiology -- which I don't think you should -- I would say that just because a chemical is positive in a rat test doesn't give us the information we need to call it a human carcinogen," Gold says.
No one denies that acrylamide causes cancer, but neither is anyone sure just how much of the chemical is dangerous. Animal studies conducted in the late 1980s exposed rats to 100,000 times the amounts humans have received in occupational exposures.
"You're dealing here with very low levels of a potentially toxic compound," says Michael Pariza, a food toxicologist at the University of Wisconsin. "We know that rats and mice are not humans, but we use these tests simply because we don't have any alternative. It has some rough predictive marks you can follow, but no one believes these models extrapolate with any predictive experience."
The argument has pitted food industry scientists against government regulators.
"If they understand the chemical properties of acrylamide, they should be concerned about its mutagenicity, toxicity and carcinogenicity," says Ronald Melnick, a toxicologist at the National Institute for Environmental Health Sciences.
"Is there uncertainty? Yes. But do we know that it's a carcinogen? Absolutely. This isn't one of [those] chemicals you just pooh-pooh because you don't like the animal data."
Some hope it may be possible to control acrylamide in food, since the levels vary between brands -- even brands within the same company.
James Wheaton, director of the Oakland-based Environmental Law Foundation, which works to enforce environmental laws, says he is encouraged that may be the case.
He cites the fact that some oils contribute to higher acrylamide levels than others. Other variables seem to include the kind of potatoes used, how they are stored and length of cooking time.
The Environmental Law Foundation is one of three nonprofit organizations that sued the giant potato chip makers before the state filed its own lawsuit under Proposition 65, the 1986 ballot initiative requiring "clear and reasonable" warnings for known carcinogens.
It did so, says Edward G. Weil, assistant attorney general leading the case against the food makers, only because the FDA has declined to act.
"They've been studying the problem for three years now, and they have no schedule or timetable for doing anything," Weil says. "Given the fact that we have this law in the state for dealing with chemicals in the food, it was time to do something."
