Some e-cigarettes or vapes popular among teenagers are packed with toxic metals, cancer-causing chemicals and a much higher amount of nicotine than legally allowed, RTL Nieuws has found.

The broadcaster asked 10 schools across the country to send them vapes they had confiscated from pupils and had them analysed. What they found has worried experts, the broadcaster said.

A specialised lab in Liverpool tested the fluid in the vapes and the vapour inhaled by the user.  Eight in 20 vapes contained too much nicotine while seven out of 20 vapes contained formaldehyde. Lead was found in three out of 20 vapes while several of the vapes contained nickel, acetone, iron and other compounds, all of which are toxic and contribute to lung disease. All of the vapes were found to contain more than the legal amount of liquid.

“This shows that these are harmful products, particularly for children whose brain is still developing,” toxicologist Remco Westerink said. Some of the vapes had a nicotine content of 200 to 400 cigarettes, Westerink said. “That can lead to severe problems, from brain damage related lack of concentration and mood swings to addiction,” he said.

One vape contained 11 times the allowed amount of 20 milligrammes of nicotine. “If you were to smoke this in one go, it would seriously damage health or even kill you,” he warned. Most vapes contain enough content for 600 inhalations but some of the confiscated ones more than doubled that amount.

According to addiction centre Trimbos, youngsters who vape also smoke, putting paid to the idea that one discouraged the other.

Trimbos tobacco expert Esther Croes said the investigation confirmed international research into the harmful effects of electronic cigarettes.

Westerink said the investigation is an “eye-opener”. “Despite the ban these flavoured vapes are still around in schools. Now that it’s been shown they can contain toxic substances, sometimes in huge amounts, it brings home to people that vapes are not a safe product but a highly dangerous one,” he told the broadcaster.

Research has shown that one in five youngsters between 12 and 25 had vaped in the last year, varying from once a month to every day, Flavoured vapes have been banned since January 1 but, RTL found, are still readily available. Most schools also prohibit vaping on their premises.