National Advisory Committee on Drugs and Alcohol

The NACDA was established in response to the drug problem to assist in our continued need to improve our knowledge and understanding of problem drug use.

The goal of the NACDA is to advise the Government on problem drug use in Ireland in relation to prevalence, prevention consequences and treatment based on our analysis and interpretation of research findings.

Cannabis smokers at increased risk of developing cancer

Wednesday 1st September 2004

The first Irish review of scientific evidence about cannabis has been released. The report, entitled ‘An Overview of Scientific and other Information on Cannabis’ and published by the National Advisory Committee on Drugs (NACD), was launched by Mr Noel Ahern, TD, Minister of State for the National Drug Strategy today. It highlights a number of issues in relation to cannabis in particular the evidence that regular cannabis smokers are at an increased risk of developing some cancers. Most regular users of cannabis in Ireland smoke cannabis in the form of a joint, thereby also using tobacco products.

The report was prepared by a collaboration of researchers from a range of disciplines and backgrounds: Dr Mark Morgan, Head of the Education Department at St. Patrick’s College, Drumcondra, Dr Claire Collins, Research Director of Social and Clinical Research Consultants (SCRC), Mr Johnny Connolly, Criminologist and Research Officer with the Drug Misuse Research Division of the Health Research Board and Dr Dominique Crowley, Specialist in Public Health Medicine. The report also draws attention to information gaps and highlights the need for further detailed research on the effects of cannabis use in Ireland.

"I believe the report shows that cannabis is a complex substance and, notwithstanding the fact that it is not as dangerous as some other drugs, it can have many damaging effects on the physical and mental health of the user, particularly the young and those who are heavy users of the drug. This report is part of the Government’s ongoing commitment to improving our knowledge base in the drugs field," Minister Ahern said.

"The consequences of much wider use of cannabis on the health of the general population have to be considered by those who support its broader availability. The approach we have adopted in Ireland is, I believe, appropriate for our circumstances and our society and we have to refute the notion promoted by some that cannabis is harmless."

The study reviewed all relevant research from Ireland and abroad up to early 2003 and revealed the following:

  • The potency of cannabis available in Ireland has increased in recent years.
  • It is estimated that up to four times the amount of tar can be deposited on the lungs of cannabis smokers as cigarette smokers if a cigarette of comparable weight is smoked.
  • Cannabis smoke contains more cancer causing chemicals than tobacco smoke leading to bronchitis and a doubling of the risk of certain types of cancer.
  • There is a strong association between regular cannabis use in adolescence and poor educational outcomes, especially early school leaving.
  • Cannabis has been shown to have beneficial outcomes for certain types of pain relief, treatment of nausea and vomiting and appetite stimulation.
  • Evidence exists to support an association between cannabis use and schizophrenia among vulnerable individuals.
  • Evidence shows that drivers under the influence of cannabis are often aware of their impairment but are unable to compensate for the loss of capability in some psychomotor skills such as staying in lane.
  • Evidence shows that heavy cannabis use produces subtle cognitive impairments of memory, attention and the organisation of complex information.
  • Regular cannabis use tends to be associated with somewhat poorer occupational and employment performance, specifically lower income, greater job instability and lower job satisfaction.
  • Dr Des Corrigan, Chairperson of NACD, said that the report highlighted the need for more research on cannabis in Ireland.

"The NACD, as a result of its analysis of this report on cannabis concluded that there is a need to monitor the potency of cannabis products on the Irish market; as well as establishing the extent of cannabis dependence, and whether there are links between cannabis use and mental ill-health and respiratory illnesses, in particular. Other significant areas where the NACD feel that further research is needed include the area of what happens when cannabis users come into contact with the legal system and an investigation of cannabis use as one of the factors in early school leaving," said Dr Des Corrigan, Chairperson of NACD.

Dr Corrigan added “whilst many gaps in our knowledge still exist, the NACD/DAIRU Drug Prevalence Survey, undertaken in 2002/03 goes a long way to answering a number of questions as some of the key findings below from the forthcoming Bulletin 3 on cannabis use shows:

  • Cannabis is the most widely used illegal drug in Ireland. This is consistent across all time periods with 17% (or 1 in 5) of those aged 15-64 having ever used cannabis (lifetime), 5% (or 1 in 20) having used in the last year (recent use) and 3% (or 1 in 33) having used in the last month (current use).
  • Hash (resin, cannabis) was the cannabis drug most commonly used with a smaller number of respondents reporting use of the herbal form (grass, weed, marijuana).
  • The vast majority of cannabis users took cannabis in a joint rather than using a pipe or bong and only a small number took cannabis in food.
  • More than two thirds of those surveyed agreed that cannabis use should be permitted for medical reasons.
  • Almost the same number disagreed that cannabis use should be permitted for recreational reasons.
  • The majority of those surveyed disapprove of people smoking cannabis occasionally.
  • The majority perceived moderate to great risk associated with regular cannabis use.


For further information:

Jane O’Dwyer (086 6491408) / Pat Montague (087 2549123) at Montague Communications, Tel. 01 8377960

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