Concern over surge in cannabis cultivation

  • Deborah Condon

The cultivation of cannabis in Ireland is on the increase and home grown versions of the drug appear to have a higher potency than imported versions, a new study has revealed.

The aim of the research, which was carried out on behalf of the National Advisory Committee on Drugs (NACD), was to establish the THC content of cannabis available in Ireland.

THC (tetrahydrocannabinol) is the main psychoactive part of cannabis - in other words, the part that affects a person's mind or behaviour the most. According to NACD chairperson, Dr Des Corrigan, ‘there is growing concern about rising THC levels particularly in herbal cannabis of the ‘skunk' or ‘weed' variety'.

He noted that while most of the cannabis products seized by the Gardai here are thought to be imported, there is growing concern about a ‘surge' in cannabis cultivation in Ireland. While Ireland's climate does not allow for cannabis to be grown outdoors, it can be cultivated indoors with specialist equipment.

"Many of the plants being grown here are genetically selected to ensure they produce high levels of THC, but they also lack a substance called CBD, which seems to protect the brain from the effects of THC, which can include psychosis," explained Dr Corrigan.

Psychosis refers to a mental disorder characterised by a loss of contact with reality, such as schizophrenia. Psychotic symptoms can include hallucinations, delusions and severe thought disturbances.

He said that samples taken from cannabis seizures nationwide, including Dublin, Cork, Limerick and Tipperary, showed that versions of the drug cultivated in Ireland ‘had very high THC levels and very low CBD levels compared to imported herb and resin (hash)'.

Dr Corrigan said that these high levels of THC in cannabis raised ‘serious health concerns'.

"Recent UK studies have shown that there is a higher risk of psychosis in those who smoke high-potency cannabis products compared to those who smoke hash, which contains both THC and CBD.

"While it is the high THC content and frequency of use of the former products that may cause psychotic episodes, it is also thought to be attributed to the amount or lack thereof of CBD, as CBD appears to decrease the effects of THC when ingested together," he explained.

Recent findings from the 2010/11 Drug Prevalence Survey show that cannabis is still the most commonly used illicit drug in this country, therefore monitoring its potency ‘is extremely important', Dr Corrigan added.

The study was carried out on behalf of the NACD by the Forensic Science Laboratory.

Discussions on this topic are now closed.