The chemical N-Nitrosodimethylamine, or NDMA, is a yellow liquid that dissolves in water. It doesn’t have an odor or much of a taste. It’s known to cause cancer in animals and is classified as a probable carcinogen in humans—it’s most toxic to the liver. A single dose of less than a milligram can mutate mice cells and stimulate tumors, and 2 grams can kill a person in days. An Oklahoma man poisoned the family of an ex-girlfriend in 1978 by pouring a small vial of NDMA into a pitcher of lemonade. In 2018 a graduate student in Canada sickened a colleague by injecting the chemical into his apple pie.
NDMA no longer has industrial uses—it was once added to rocket fuel—but it can form during industrial processes at tanneries and foundries as well as at pesticide, dye, and tire makers. It can be found in drinking water disinfected with chloramine. It’s in tobacco smoke, which is one reason secondhand smoke is dangerous, and it’s what makes eating a lot of cured and grilled meat potentially risky. The U.S. Food and Drug Administration says it’s reasonably safe to consume as much as one microgram—one millionth of a gram—of NDMA a day….