"It was known that there is acrylamide in coffee beans," Oeko-Test editor Hella Hansen told Reuters. "We wanted to know how much of it gets into a cup of coffee." The test found the substance was present in brewed coffee, although in much lower quantities than in ground coffee beans.

Preliminary scientific studies have found that acrylamide--a substance found in french fries, potato chips, water and carbohydrate-rich foods such as bread that are fried or baked--can cause cancer in animals.

The World Health Organization ( news - web sites) (WHO) said in June that acrylamide was a cause of concern but more research was needed about the possible effect on humans. The US Food and Drug Administration ( news - web sites) has also said the information currently available about acrylamide is not sufficient to assess the substance's impact on public health.

According to the American Cancer Society ( news - web sites), "the vast majority of studies agree that coffee has not been shown conclusively to have a link to bladder, breast, lung, pancreatic, prostate or any other cancers."

Earlier studies found that some compounds in coffee seemed to be anti-mutagenic, meaning they prevent DNA damage. Experts point out coffee is a highly complex food and no studies of a single compound are likely to show for certain what its health effects might be. The head of the German coffee federation, Winfried Tigges, said acrylamide was not present in raw coffee beans, but was formed when they were roasted.