The greatest share of drug-related diseases and deaths in the European Union continues to be the result of heroin use, an EU report concludes. The report released in Portugal Wednesday by The European Monitoring Centre for Drugs and Drug Addiction estimates there are more than 1.3 million regular opioid users in the European Union and Norway. A special review on drug-related deaths published alongside the report estimates 10,000 to 20,000 users are dying in Europe each year, mainly from overdoses but also from other causes. Most of the victims are male and in their mid-30\'s. Data gathered for the report indicates while the levels of opioid use remains relatively stable, \"the characteristics of Europe\'s opioid problem are changing.\" The main changes are those in treatment for opioid use are older, fewer inject their drugs and opioids other than heroin are being used in some parts of Europe, the report said. Some countries in Europe report synthetic opioids have displaced heroin. In Estonia, 75 percent of those entering treatment listed fentanyl as their main drug. Fentanyl use is also reported in a number of other countries, the report said, particularly in eastern member states. Fentanyl is more potent than heroin and is associated with overdoses. In Finland, buprenorphine is most frequently reported as the primary drug among those entering treatment.