The cannabis round table discussion is being hosted by the Social Development Department this week.

JOHANNESBURG - South Africa's first ever conference on the use of cannabis as a medicine on Thursday heard that up to four million people were estimated to be using the drug in southern Africa, and while millions are spent to eradicate it, these efforts yield little results and often disadvantaged the poor.

The cannabis round table discussion was being hosted by the Social Development Department in Benoni this week and brought together doctors, lawyers, religious leaders and NGOs to discuss the viability of partial legalisation.

This the result of a Medical Innovation Bill tabled by late IFP MP Mario Oriani-Ambrosini in the National Assembly last year.

Several cannabis experts put forward an argument for the regulation and while most agreed it would be difficult to control, they say it was necessary.

Public Health Consultant Andrew Scheibe said cannabis cultivation took place in South Africa's rural areas and despite spraying crops with harmful pesticides it had not reduced the demand or supply.

"So it has no effect on the people that buy it, it has very little on production because people move elsewhere, it's called the balloon effect, and it has significant harms from a biological point of view include the harm of the herbicide which is sprayed to humans."

Scheibe said instead the villagers who grew the crops had been the worst affected due to a lack of alternative economic opportunities.

The event was also criticised by the Rastafari group who said the number of pro-legalisation speakers was not enough.