Three deaths in Poland have been confirmed to be linked to "ecstasy" pills with the Superman logo that contain the highly dangerous PMMA rather than MDMA, highlighting that these potentially lethal drugs are still in circulation in Europe.

The European Monitoring Center for Drugs and Drug Addiction (EMCDDA) issued an alert on July 16, stating that three deaths occurred between July 7 and 8 in the West Pomeranian region of Poland.

Similar alerts have been issued in throughout Europe in the past eight months following PMMA-related fatalities in the UK and Sweden. What's more, Public Health England received an alert from Spanish authorities in January that pills containing PMMA had been discovered being sold in Madrid.

PMMA is a drug that has similar effects to MDMA (the chemical normally found in ecstasy). However, PMMA can kill at lower doses than MDMA. What's more, the drug takes longer to take effect meaning users are at risk of increasing their dose if they believe they have been sold MDMA.

To find out more about differences between the two, and for harm reduction advice, see Release's infographic here.