In the same way as cigarette smoke.
Experts from the food standards Agency (FSA) in the UK say that the potatoes, fried to brown, produces acrylamide which can cause cancer. The highest level of this substance seen in starchy foods (bread, potatoes, cereals, coffee), which were prepared over long periods of time at temperatures above 120 degrees.
The darker crust color of potatoes, the higher the content of acrylamide. Scientists also suggest not to store potatoes in the refrigerator. It increases the level of sugar, which can potentially lead to the development of acrylamide during cooking.
The experiments that scientists conducted on animals have shown that acrylamide causes damage to DNA and causes cancer. Does this substance on man, they still can not say for sure.
Acrylamide is also found in tobacco smoke, so smokers get a large dose of that substance than people who do not smoke.
In everyday life the person uses a large amount of acrylamide, so experts suggest the FSA to stick to a healthy diet.