Acrylamide in Food
Uncharted Territory

GISELLE WEISS / Science v.297 5jul02

More questions than answers emerged from a high-profile group of food experts who met in Geneva last week to consider what should be done about acrylamide. This compound, identified long ago as a potential industrial hazard, has now been found in many cooked foods. The World Health Organization (WHO) responded by sponsoring a safety data review. At the end of a 3-day closed meeting, the WHO experts issued an urgent call for more research, but the most striking aspect of their 12-page summary report, released 28 June, might be how little new information it gives on health risks.

Risk unknown. High-temperature cooking
can produce acrylamide in starchy foods.

Acrylamide has been used since the 1950s to make paper and dyes and to purify drinking water. Its only known adverse effect in humans—most of whom were exposed in the workplace—is neurological damage. But because it can induce cancer and heritable mutations in lab animals, acrylamide is classed as “probably carcinogenic to humans” by the International Agency for Research on Cancer (IARC) in Lyon, France. Considering the available evidence, “we have to think about the possibility that this could be a human carcinogen,” said Swiss health official Dieter Arnold, who chaired the meeting, at a press conference in Geneva.

The news that acrylamide is pervasive came as a shock. In April, Swedish researchers announced that the compound was present at high levels in starch-based foods cooked at high temperatures, such as potato chips and certain breads. Initially dismissed as a food scare, the issue took on new urgency when British, Norwegian, and Swiss scientists obtained similar findings in cereals, French fries, and cookies. To find carcinogens in food is not new, says Arnold. But it is new to find such high levels of a cancer-causing substance —and in staples. The expert group also considered risks for children, who may “take in more acrylamide per kilogram of body weight,” says Peter Farmer, a toxicologist at the University of Leicester, U.K.

Acrylamide binds to nerve cell proteins, interfering with transport of essential materials, says Peter Spencer, a neurotoxicologist at the Oregon Health and Science University in Portland. In rats, he says, protein binding might also be responsible for injury to testes, whereas heritable mutations and tumors are likely related to DNA damage through another mechanism. But extrapolating from animal studies is difficult, and there is no solid evidence of acrylamiderelated cancer in humans. The question is whether the levels of acrylamide found in foods pose a serious risk over time.

Although scientists “understand how to measure acrylamide in foodstuffs now,” says Laurence Castle of the Central Science Laboratory in York, U.K., they have not set rigorous analytical methods. And almost nothing is known about how acrylamide is formed through cooking, except that it develops at temperatures above 120°C, and amounts increase with cooking time.

Nor is food the only source: Tobacco smoke and environmental exposure are two others. Acrylamide could even be generated naturally in the body. Although minute amounts of acrylamide are present in drinking water, “it is most unlikely that anyone would consume dangerous amounts of acrylamide by drinking tap water,” according to Jerry Rice of IARC. Estimating exposure is also tricky, because diets vary among people and across cultures.

For now, no one is calling for a change in dietary habits. The WHO expert committee has recommended cooking food thoroughly but not excessively, eating a balanced and varied diet, investigating ways of reducing acrylamide levels, and setting up an international network to share information. The U.S. Food and Drug Administration (FDA) has developed a methodology and begun testing a limited set of foods, according to an FDA official. McDonald’s Corp., meanwhile, has issued a statement claiming that its French fries have been unfairly targeted.

Acrylamide in food has probably been around since fire, says Farmer: “I think it’s an achievement of toxicological science to have discovered it now.” But the precautionary principle dictates that once you have established the presence of a known carcinogen, you are bound to investigate it. “What we know today may change tomorrow,” says Rice.

Giselle Weiss is a writer in Allschwil, Switzerland.