SHANGHAI, China (AFP) — Two more Chinese drug makers have announced that a blood-pressure medication they exported to Taiwan contained a potentially cancer-causing impurity, a month after the same problem at another Chinese manufacturer prompted a global recall. Tianyu Pharm and Rundu Pharma said batches of valsartan, an active ingredient widely used in medications for high blood pressure and congestive heart failure, contained N-nitrosodimethylamine (NDMA), which is believed to potentially cause cancer through long-term use. […]