Canada’s top medical journal warned Monday that the imminent legalization of cannabis for recreation use poses a major health concern despite broad support for ending the prohibition.

Diane Kelsall, editor in chief of the Canadian Medical Association Journal, called the October 17 launch “a national, uncontrolled experiment in which the profits of cannabis producers and tax revenues are squarely pitched against the health of Canadians.”

Any increase in pot use “should be viewed as a failure of this legislation” and convince Ottawa to amend the Cannabis Act, she wrote in an editorial in the journal’s online edition.

The government defends legalization as intended to get marijuana out of the hands of youths and beyond the control of drug lords.

The law has broad popular support, and has generated a booming marijuana industry in anticipation of full legalization, which goes into effect on Wednesday.

A survey published Monday found that 70 percent of Canadians support or accept pot legalization. Conducted in early September by Abacus Data, the survey has a 1.79 percent margin of error.

“Attitudes towards cannabis reflect the fact that a majority do not see it as any worse than consuming alcohol,” Abacus said in a statement.

But Kelsall warns that the hundreds of licensed growers that have popped up over the past year are driven by profit, and not concern over public health.

She points out that Health Canada, the country’s health ministry, estimates that pot legalization will cause a problem in one in three adults, and addiction in ten percent of users, with higher risks in youths.

“We cannot expect cannabis firms to restrict their growth ambitions or to have use reduction as a goal,” Kelsall said.

“Cannabis companies may initially focus on attracting current consumers from black-market sources, but eventually, to maintain or increase profits, new markets will be developed as is consistent with the usual behaviour of a for-profit company.”

Marketing efforts, she suggested, might include encouraging current users to use more, or attracting a younger demographic.