There is ample evidence NDMA causes cancer in animals: -A 1989 toxicological profile by the Agency for Toxic Substances and Disease Registry (ATSDR) spelled out how NDMA caused mice to develop liver, stomach, and lung cancer. -A 1991 medical journal article chronicled how dosing rats with NDMA caused liver and esophageal tumors. -The World Health Organization said studies positively associate NDMA with gastric or colorectal cancer.