The drugs, known as generics because they are out of patent control, make up around 90 percent of all drugs being prescribed—and the contaminated products could be shipped to more than 30 countries, researchers estimate.
The FDA recalled the blood pressure drug valsartan (marketed as Diovan) after samples had been found to contain up to 17 mcg (micrograms) of NDMA (N-Nitroso dimethylamine), a cancer-causing chemical that is safe at just 1 mcg.
Since then, two other generic drugs, irbesartan and losartan, have also been recalled. Around 10 drug companies are making the drugs, as they are out of patent protection, and are using manufacturing plants in India and China.
Most of the drugs enter Western markets without being tested for contaminants. In the US, the FDA checks just 1 percent of drugs, an investigation by Bloomberg Business Week has discovered.