Alarmed about new studies indicating that potato chips, french fries and certain types of bread contain a substance that may cause cancer, the World Health Organization has convened an emergency meeting to evaluate the research and decide what action to take.
The three-day meeting, which opens Tuesday, follows the publication in April of a Swedish study that some starch-based foods cooked at high temperatures contained acrylamide.
Acrylamide, used to produce plastics and dyes and to purify drinking water, has been shown to be carcinogenic in animal experiments and is suspected of causing cancer among people exposed to high levels for long periods. Although traces of it have been found in water, its possible presence at high levels in basic foods came as a shock.
"If what we know from water and animal experiments is true, it could be a very significant source of cancer in humans," said Jorgen Schlundt, coordinator of WHO's food safety division. "It is not just another food scare," he said.
Such was the level of WHO concern that it organized the gathering of 25 international experts within two months of the publication of the Swedish study. According to Schlundt, this set a "world record" for the U.N. health agency, which usually takes about one year to organize meetings of experts to review scientific data.
Although much is known about acrylamide and its effects in animals, there is far less information about its effects on humans. After the study was released in April, some U.S. scientists urged consumers to be patient in awaiting more investigation.
"I think we need to step back a little bit and wait for greater discussion of the issue and see the findings presented in more detail," said Carl Winter, a toxicologist at the University of California at Davis. "The most important thing is not the presence or absence of any type of ingredient, but how much is there."
Mary Ellen Camire, a food scientist and nutritionist at the University of Maine, was skeptical about any link to cancer and said it was important to remember that whole-grain bread and potatoes contain a lot of important nutrients.
"The risk-to-benefit ratio is hard to estimate," she said at the time. "We eat a lot of strange chemicals, but that's life. You just have to get a balance."
Schlundt said subsequent studies in Norway, Britain and Switzerland basically backed up the findings of Sweden's National Food Administration.
"It is not a case of a batch of wrong results from scientists," he said. "Everybody who has any expertise understands this is a potential threat."
In voicing misgivings about the validity of the Swedish results, which were based on 100 foods, scientists noted that they were released at a government news conference rather than passing through normal peer review procedures in a scientific journal.
The Swedish researchers said that "fried, oven-baked and deep-fried potato and cereal products may contain high levels of acrylamide." The same results were not found in boiled products.
Swedish government scientists estimated it could be responsible for several hundred of the 45,000 cancer cases in the country each year, based on experiments in which rats were fed fried food.
Schlundt said the type of cancers provoked by acrylamide in animals were not just limited to the digestive tract, but also included the mammary and testicular glands, and skin. But he stressed there was no evidence to suggest this could apply to humans.
He said it was premature to predict whether the meeting would urge dietary changes, or recommend further studies in specific areas.
Regardless of the acrylamide fears, there is basic consensus that people should limit consumption of fried and fatty foods if they want a healthy diet. But it would prove more difficult to issue advice concerning bread and only certain types are so far implicated given its importance in many national diets.