Only a minimal amount of heavy metals are removed in the filtration process when smoking shisha, also known as a hookah, says research in the journal BMC Public Health.
On average, 3% of heavy metals present in tobacco are removed and this would not be enough to protect users from exposure.
Shisha is often thought to be less severe than cigarette smoking due to bubbling through water.
However, a shisha smoking session, which can last up to an hour, can expose someone to 100-200 times the volume of smoke in a single cigarette.
Shisha is a waterpipe in which a mixture of tobacco and flavourings or molasses sugar is smoked.
Researchers from the German Jordanian University and the Royal Scientific Society Amman-Jordan, analysed four tobacco samples of the most popular brands bought at a local market in Jordan.
Each was tested for total heavy metals, including copper, iron, chromium, lead and uranium.
Lead researcher Akeel Al-Kazwini, says: “Since the trend of smoking waterpipe has increased markedly among the young in the last decade, not only in the Middle East but worldwide, our research adds to the evidence about its potential health hazards. It is also important to highlight the fact that water is mainly cooling the smoke, and not filtering it as is commonly believed.”
The most abundant metal present in the smoke tested was uranium, which was present on average in 800 parts per billion across four samples. The WHO (World Health Organisation) recommended maximum limit of Uranium in drinking water of 30 parts per billion (equivalent to 30 micrograms per litre).
Akeel Al-Kazwini says waterpipe tobacco industry operates without regulation and the impact of health warning labels on waterpipe use has not been extensively investigated.
NOW WATCH: Briefing videos
Business Insider Emails & Alerts
Site highlights each day to your inbox.