WASHINGTON (AP) -- A consumer group wants the government to force makers of french fries and other foods to reduce levels of a possibly cancer-causing substance in their products.

The substance, called acrylamide, made headlines last year when it was discovered in fries, potato chips and other high-carbohydrate foods cooked at high temperatures. Junk food's not the only culprit: The Food and Drug Administration later found fairly high acrylamide levels in foods from breakfast cereal to coffee.

While acrylamide causes cancer in animals, scientists haven't yet proven if people really are at risk -- and if so, what is a safe level. So while the FDA encourages manufacturers to look for ways to lower acrylamide levels in food, it hasn't yet ordered reductions.

The Center for Science in the Public Interest petitioned the FDA on Wednesday to set temporary acrylamide limits for foods known to contain high amounts until the risk issue is settled.

Acrylamide levels are highly variable, fluctuating from brand to brand and even batch to batch. CSPI urged that the median level found in each type of food become the limit.

Take frozen french fries: Tests of 12 brands found acrylamide levels ranging from 20 parts per billion to 218 ppb. The median level -- half the brands were higher and half lower -- was 77 ppb, CSPI's preferred limit.

"We're saying that the most-contaminated brands should certainly be able to get to the level of half of their competitors," said CSPI executive director Michael Jacobson. "We're not saying put a man on Jupiter. This is something that should be quite practical."

Food manufacturers are hunting ways to lower acrylamide without altering food safety or taste, and say it's not a simple task.

Setting levels "is not necessary at this time, particularly when there isn't really good science to base that rulemaking on," said Tim Willard of the National Food Processors Association.

The FDA will examine the petition, but its plan for now is to settle scientific questions about acrylamide before trying to set acceptable levels, said agency spokeswoman Kim Rawlings.

Copyright 2003 The Associated Press. All rights reserved.