Dhaka, April 16 -- The World Health Organization issued an alert on Monday warning drugmakers of five contaminated batches of propylene glycol, an ingredient used in medicinal syrups, that appear to have been falsely labelled as manufactured by Dow Chemical DOW.N units in Asia and Europe.

The Drug Regulatory Authority of Pakistan (DRAP) issued three alerts between January and March over high levels of ethylene glycol (EG), an industrial solvent known to be toxic, found in drums purportedly made by subsidiaries of Dow Chemical in Thailand, Germany and Singapore.

DRAP sent suspect drums of propylene glycol, a sweet-tasting alcohol used in over-the-counter medicines such as cough syrups, for testing. The samples were found to have EG conta...