Illegal THC vapes are becoming more popular among teenagers and many unwittingly buy vapes containing extremely addictive synthetic cannabis, or spice, current affairs programme Zembla reported.

A probe by the programme showed that some teens at schools and care institutions in Amsterdam, The Hague and Noord-Brabant became ill after using the spice vapes. Some fainted or vomited and others had to be admitted to hospital.

Spice is many times more addictive than THC, and even a little can lead to dizziness, hallucinations, arrhythmia and vomiting. The substance is similar to regular cannabis but according to addiction centre Jellinek, it is difficult to determine the dosage, which makes the effect hard to predict.

Illegal vapes are easily available from social media apps, such as Snapchat and Instagram. This week, consumer watchdog ACM  opened an investigation into Snapchat for allowing the large-scale illegal sale of vapes to minors, in breach of European legislation.

Most teens think they are dealing with regular THC, Zembla journalist Evelien Vehof told broadcaster NOS, but all THC vapes analysed by Zembla turned out to contain synthetic cannabis.

The user group is still relatively small but large enough for Amsterdam regional health board and the Jellinek clinic to raise the alarm. Youth organisations, particularly those dealing with 13 to 16-year-olds, have been warned about the health risks of THC vapes, with and without spice.

According to Dutch law, vapes can only be sold to adults and must contain only tobacco. Flavourings and other substances are banned, and vapes containing THC are banned under the Dutch opium law.

Apart from spice and THC, illegal vapes have also been found to contain lead and other toxic heavy metals.

A campaign to warn teenagers against the dangers of illegal vapes has been ongoing since May.