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 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 contamination of 0.76-100 percent, according to the WHO. International manufacturing standards say only trace amounts of EG, below 0.1 percent, can be considered safe.

Contaminated cough syrups made in India and Indonesia have been linked to deaths of more than 300 children globally since late 2022. The medicines were found to contain high levels of EG and diethylene glycol, leading to acute kidney injury and death. In the Indonesia case, authorities found that one supplier had placed false Dow Thailand labels onto drums containing EG that it sold to a distributor for pharmaceutical use.

Several of the batches seized by DRAP were labelled as having been manufactured in 2023, the WHO said, months after the agency issued a global alert calling on drugmakers to verify the quality of their suppliers.

The WHO said Dow confirmed that the materials identified in its Monday alert and found by DRAP were not manufactured or supplied by the company.

"The propylene glycol materials identified in this alert are considered to have been deliberately and fraudulently mislabelled," the WHO said, noting batches may have been distributed to other countries and still be in storage.

Dow did not immediately respond to a request for comment.

The WHO alert comes the same week regulators in Tanzania and Rwanda joined Nigeria, Kenya and South Africa to recall batches of Johnson & Johnson children's cough syrup after Nigeria said it found high levels of diethylene glycol, an industrial solvent known to be toxic.

The batch of Benylin Paediatric syrup recalled was made by J&J in South Africa in May 2021, although Kenvue now owns the brand after a spin-off from J&J last year.