Read out It is the perfect misery: The possibly cancer-causing substance is in biscuits and crispbread, in coffee and cereal mixes. It is also abundant in chips and French fries. And even in Vanillekipferln and gingerbread, it was reported in the run-up to Christmas, you will find it. How and where acrylamide is produced, what causes it and what dangers it entails, reported Bild der wissenschaft in issue 2/2003, published on 21 January. Since the subject moves many and affects all, we publish this article by Martin Lindner in advance on the Internet. "We are dealing with the biggest food problem of recent years, " says the spokeswoman of the Federal Institute for Risk Assessment Irene Lukasowitz. She speaks of acrylamide, a substance that has long been known in the manufacture of plastics, cardboard or paint, but was recently and completely surprisingly discovered in numerous foods. When Swedish scientists reported on their find last April, experts were astonished - and at the same time they were shocked by the possible consequences. Because it is known from animal experiments that acrylamide causes at least in rats tumors in the thyroid, testes and breast. So is the substance also a creeping poison in daily bread for humans?

Meanwhile, even the food industry has become sensitive - and the policy has responded. In August, for example, a program initiated by the Federal Ministry of Consumer Affairs was launched to reduce acrylamide concentrations in food through constant food controls and improved production methods. Because recent research shows how the toxic substance in food can be at least partially avoided.

For a long time it was not even clear why acrylamide even appeared in food. In contrast to the scandals uncovered in the past, the substance does not get into the food through illegal admixtures. Rather, it is produced as a by-product during roasting, roasting, baking or frying - and this both in the food factory and at home.

"Maybe acrylamide has been in the diet since humans invented fire, " commented acrylamide specialist Dr. Josef Schlatter from the Swiss Federal Office of Public Health. This is certainly no reason to ignore the problem. For after all, the risk of cancer by acrylamide by ten powers seems more likely than other, long-delayed by cancer doctors substances such as the mold poison aflatoxin or benzopyrene, which may arise when roasting and smoking of meat. display

Acrylamide is present in so many foods that nobody can miss it. While the substance is found in fried meat apparently only in traces, many grain and potato products seem to be particularly burdened. Again and again in the headlines were two: Chips and fries. After all, it has become partially clear which way the poison gets into the fast food treats. As two teams recently reported around the British researcher Donald Mottram from the University of Reading and Richard Stadler from the Nestlé Research Center in Lausanne, the so-called Maillard reaction plays a key role. In the process observed by the French chemist Louis Camille Maillard about 90 years ago, proteins and sugars combine to form new molecules at high temperatures. That is indeed desired. This results in numerous pigments and flavors, the bread crust only handsomely, the roast first tasty and make the fries first crunchy.

But there is a downside to this: acrylamide evidently forms via exactly the same chemical pathways, especially when a food contains the amino acid asparagine. In fact, asparagine is found in many cereal and especially potato varieties to a large extent. "That's not the whole truth, of course, " says Hagen's food chemist Christian Gertz. Because asparagine is indeed a probable main source of the toxin. But other amino acids are likely to contribute to acrylamide formation, which also seems to be dependent on many other factors, as Gertz has recently demonstrated. Thus, the water content of foods plays a role as well as the baking or frying temperature, the pH and even the type of frying oil used. Such complex - and by no means completely understood - mechanisms of origin might explain why, for example, one type of crispbread contains 20 times more acrylamide than another.

Of course, this is the starting point for minimizing the sometimes questionable concentrations. Thus, the acrylamide content is already reduced if, in the production of crispbread, the edges are no longer baked so brown or in the production of chips, the frying temperatures are lowered. Potato varieties with a low asparagine content could also make many products safer in the future. Meanwhile, researchers are trying to answer another question: what happens to acrylamide in the body? For the fact that the substance is found in foods does not say anything about the extent to which - and by what mechanisms - it harms the organism. The common hypothesis is that a part of the acrylamide is degraded by a special enzyme system, the so-called cytochrome P 450 system. It plays a role in numerous detoxification processes in the liver and has evidently developed particularly strongly in humans in the course of evolution. The Cytochrome P 450 system, for example, transforms highly toxic hydrocarbon compounds, which are produced, for example, into the combustion of firewood, into water-soluble molecules. They can then be excreted via the urine.

The problem with this is that during the detoxification processes, intermediates sometimes form which, although they no longer pose an acute danger, can permanently damage the DNA and promote cancer. Say: The body produces some of the cancer poisons themselves. Obviously also in acrylamide. Because this results in the organism, the derived product glycidamide - "the actual cancer-causing component", as Prof. Helmut Greim of the Technical University of Munich judges. Glycidamide binds to the DNA, leading to dangerous mutations. "However, less glycidamide is produced in humans than in mice or rats, " says Greim - which explains why the risk of cancer may be lower than animal studies suggest. Josef Schlatter, however, considers this argumentation to be rather unconvincing. Because it is still unclear whether glycidamide formation is actually the only cancer-causing mechanism. In addition, it was by no means certain how much - and if anything - genetic differences between humans and animals mattered.

Nevertheless, Schlatter also regards with skepticism the speculations that are coming to fruition about how many people could use acrylicamide to contract a cancer. It is known that probably around one third of all cancer sufferers can be attributed to dietary factors. Swedish researchers had projected that acrylamide might be behind every eighth of these neoplastic tumors. It would cause 10 000 to 15 000 cancers a year in Germany.

But it could just as well be 100 to 150, emphasizes Schlatter. For although it is indisputable that acrylamide triggers tumors in experiments when the animals are treated with very high doses of the poison. On the other hand, how the much smaller quantities that humans take up with daily food needs to be calculated using mathematical models. "These numbers tell us more about the used calculation model than reality, " says Schlatter.

However, many experts agree that the problem is by no means limited to food. A potentially no less important source of danger are cigarettes. As a new study by environmental physician J rgen Angerer from the University of Erlangen-N rnberg has shown, in smokers four times higher levels of acrylamide can be measured in the blood than in non-smokers. "Apparently, acrylamide is produced directly when smoking cigarettes, " comments Angerer. Maybe the right slogan would not be: goodbye to fries, but: cigarettes bye!

Martin Lindner

On the pages of the Ministry of Consumer Affairs, you can find out how acrylamide formation can be avoided when cooking at home.

You can ask questions to a forum of experts here.

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