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.
In July 2018 the FDA announced that NDMA had been found in the widely used blood-pressure medicine valsartan and started overseeing a recall of drugs from three companies. They’d all bought the active ingredient for their valsartan from Zhejiang Huahai Pharmaceutical Co., one of China’s biggest generic companies. The recall has since been expanded 51 times, to include two related drugs, irbesartan and losartan, made by at least 10 companies—some since 2014. Drugs sold to millions of people in 30 countries could be tainted.
Some of the contaminated valsartan contains as much as 17 micrograms of NDMA in a single pill. That’s equivalent to eating 48 pounds of bacon. The FDA estimates that for every 8,000 people who took the highest dose of contaminated valsartan daily for four years, there would be one additional occurrence of cancer. “We had to be honest about that, but it’s not a great message for the consumer,” says Janet Woodcock, director of the agency’s Center for Drug Evaluation and Research. “Throw a couple of lamb chops on the barbecue and you’d find nitrosamine after a good grilling. You have to put this in perspective.”
— Read on www.bloomberg.com/news/features/2019-09-12/how-carcinogen-tainted-generic-drug-valsartan-got-past-the-fda