The rich, roasted aroma of coffee or the golden-brown colour of crispy French fries are enough to set most mouths watering. But the high-temperature cooking that gives these foods their alluring taste, scent and texture also adds a sting: acrylamide, a probable human carcinogen. Swedish scientists discovered in 2002 that a wide range of baked and fried goods contain worryingly high levels of acrylamide1 — a simple organic molecule that is a neurotoxin and carcinogen in rats. The finding sparked an international effort to reduce concentrations of the chemical by changing ingredients and cooking methods. Ten years on, a report2 from the European Food Safety Authority (EFSA) in Parma, Italy, suggests that this effort has stalled, amid patchy monitoring, uncertainty about acrylamide’s true health effects and the challenge of weeding out a molecule present in hundreds of products.
Soon after the Swedish discovery, two teams — one led by chemist Donald Mottram at the University of Reading, UK, the other by Richard Stadler at Nestlé in Lausanne, Switzerland — unpicked the chemistry behind the problem3, 4. They found that sugars and amino acids such as asparagine found in potatoes and cereals were making acrylamide (C3H5NO) as a by-product of the Maillard reaction, the very process that generates the heady blend of colour, flavour and taste in cooked foods. Subsequent epidemiological studies involving tens of thousands of people have looked for links between acrylamide and various forms of cancer in humans, including breast5 and colorectal cancer6. For the most part, the results have been negative. In 2007, however, a Dutch study7 of almost 2,600 women found that, among those who had never smoked, women consuming about 40 micrograms of acrylamide per day doubled their risk of developing cancers of the womb or ovaries, compared with those taking in roughly 10 μg per day. And last month, a study8 showed that women who ate acrylamide-rich food during pregnancy tended to give birth to smaller babies.