2007-12-19 05:21:12
Inhaled cannabis smoke has more harmful toxins than tobacco, scientists have
discovered.
The Canadian government research found 20 times as much ammonia, a chemical
linked to cancer, New Scientist said.
The Health Canada team also found five times as much hydrogen cyanide and
nitrogen oxides, which are linked to heart and lung damage respectively.
But tobacco smoke contained more of a toxin linked to infertility. Experts said
users must be aware of the risks.
About a quarter of the population in the UK smokes tobacco products, while a
sixth of 15 to 34-year-olds have tried cannabis in the past year, making it the
most commonly used drug.
The confirmation of the presence of known carcinogens and other chemicals
implicated is important information for public health
David Moir, lead researcher
Previous research has shown cannabis smoke is more harmful to lungs than
tobacco as it is inhaled more deeply and held in the lungs for a longer period.
However, it has also been acknowledged that the average tobacco user smokes
more than a cannabis user.
Researchers from Health Canada, the government's health research department,
used a smoking machine to analyse the composition of the inhaled smoke for
nearly 20 harmful chemicals.
They also looked at the sidestream smoke, given off from the burning tip of the
product and responsible for 85% of the smoked inhaled through passive smoking.
Concentrations
In most cases, the comparison on sidestream smoke broadly mirrored that of
inhaled smoke.
However, in the case of polycyclic aromatic hydrocarbons, the toxin linked to
infertility, the researchers found concentrations were actually higher in
cigarette smoke.
The study also showed little difference in the concentrations of a range of
chemicals, including chromium, nickel, arsenic and selenium.
Lead researcher David Moir said: "The consumption of marijuana through smoking
remains a reality and among the young seems to be increasing.
"The confirmation of the presence of known carcinogens and other chemical is
important information for public health."
Dr Richard Russell, a specialist at the Windsor Chest Clinic, said: "The health
impact of cannabis is often over-looked amid the legal debate.
"Evidence shows it is multiplied when it is cannabis compared to tobacco.
"Tobacco from manufacturers has been enhanced and cleaned whereas cannabis is
relatively unprocessed and therefore is a much dirtier product.
"These findings do not surprise me. The toxins from cannabis smoke cause lung
inflammation, lung damage and cancer."
Stephen Spiro, of the British Lung Foundation, added the findings were "a great
worry".