A popular drug used to treat high blood pressure has been recalled because some products may contain a cancer-causing chemical.

In an ongoing investigation, the Food and Drug Administration has expanded the swath of the recall of the drug valsartan, which is used to treat high blood pressure and heart failure. The recalled drugs, manufactured by Zhejiang Huahai Pharmaceuticals in Linhai, China, contain the chemical N-nitrosodimethylamine, or NDMA, which has been found to cause cancer in humans based on laboratory studies, the agency says.