The European Medicines Agency (EMA) has said that impurities were found in valsartan, an active ingredient in many medicines taken by people all over the world - including in Europe - with heart conditions or high blood pressure.
In response, Chinese laboratory Zhejiang Huahai Pharmaceuticals - from which the error originated - has globally recalled any products containing this substance, due to a presence of N-nitrosodimethylamine (NDMA).
NDMA has been classed as “probably carcinogenic” when ingested by humans on a prolonged basis.
The EMA said that “there could be one extra case of cancer for every 5,000 patients” taking the substance at the drug's highest dose for seven years.
It added: "“The possible cancer risk has been extrapolated from animal studies and should be considered in the context of the lifetime risk of cancer in the EU (1 in 3)."
Yet, the agency has sought to reassure patients that the risk of immediate problems or complications was low.
In a statement, the agency said that those on any medication should not stop taking it without medical advice.
The EMA said: “It is important to note that there is no immediate risk to patients. Those who take affected medication and who have not yet been given an alternative should not stop taking their treatment without first consulting their doctor or pharmacist.”
The EMA is now conducting an investigation into the error, including requiring all drug manufacturers that have used valsartan from the lab to test for NDMA levels.
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