Bad news for people who like their starches extra crispy. The UK's Food Standards Agency recently released a report outlining the dangers of acrylamide, a chemical produced "when many foods, particularly starchy foods like potatoes and bread, are cooked for long periods at high temperatures." Basically it occurs when you bake, fry, grill, or toast many of your favorite foods for too long.
Basically, when fries, toast, potato chips, or sweet potatoes get overcooked or burnt, acrylamide -- a "probable carcinogen" also found in cigarette smoke -- is created as a byproduct. It is shown to possibly contribute to kidney, ovarian, and endometrial cancers.