Furan is found in heat-treated commercial foods and it is produced through thermal degradation of natural food constituents.[13][14] Notably, it can be found in roasted coffee, instant coffee, and processed baby foods.[15][14][16] Exposure to furan at doses about 2000 times the projected level of human exposure from foods increases the risk of hepatocellular tumors in rats and mice and bile duct tumors in rats.[17] Furan is therefore listed as a possible human carcinogen.[17]