VANCOUVER -- Many medical marijuana patients in Canada are struggling to buy pot under current laws and are turning to the black market, a University of British Columbia study has found.

About one-third of 450 patients reported in a national survey that they could not access marijuana legally under federal rules, said PhD student Rielle Capler.

"They really want to be able to use this medicine legally," she said.

"They've expressed patience and understanding that there are some growing pains, but in the meantime they're also sharing that it's really impacting ... their health and well-being."