TORONTO -- An Ontario hospital foundation pulled a Toronto-area home from its annual lottery prize offerings this week after realizing it backed onto a residence where legally grown marijuana sent out an "an intrusive odour," but police in the community say there's little they can do about such situations.

The incident involving the Markham, Ont., home meant to be a prize in the Princess Margaret Cancer Foundation's 2016 home lottery has highlighted the issue some neighbourhoods face with residences that hold Health Canada licences to grow marijuana for personal use.

"The growing of a large number of plants in the house has resulted in an intrusive odour in the neighbourhood," the foundation said in a statement, noting that it would replace the house with a cash prize worth just over $1.3 million.

Health Canada stopped issuing licences for patients to grow their own pot in 2014 in an effort to shift marijuana production to commercial producers.

Under an old system, patients had the option of growing their own marijuana, designating someone else to grow it for them, or ordering the drug directly from Health Canada. About 38,000 people were authorized under the old regime.

Under new rules, the production of medical marijuana by individuals is now illegal, with the only legal source being a licensed producer.

As the change was coming in to effect, however, several British Columbia residents went to the Federal Court asking for an injunction that would allow them to continue producing their own pot, or have a designated person do so for them, until a constitutional challenge of Health Canada's new rules could be heard.

The court granted the injunction in March 2014, meaning the old program stays alive for those who already hold licences until a final decision in the case is handed down.

As a result, if a home-owner is operating within the terms of the now grandfathered marijuana licences, there's little police can do to stop them and the smell their marijuana plants give off, York Region police said.

"We aren't notified of where those licences are given, we just don't know where they are. We typically find out about them when the community starts calling us saying 'hey there's someone growing marijuana in a house we can smell it,"' Const. Andy Pattenden explained.

"We go and investigate those complaints. We could contact Health Canada and ask if a residence or place of business have a licence ... if they have a licence and they're operating within the guidelines of the licence then there's nothing we can really do."

Pattenden said a number of Markham residents have complained about one home with a licence -- believed to be the same one near the lottery prize home -- which is located near an elementary school.

"The odour venting from that house vented right into the school playground," he said of the home, explaining that marijuana plants are "very fragrant."

"They're going to have additional ventilation that's built into the house, basically large pipes venting the odour and moisture straight out."

Generally, Pattenden added, those growing a number of marijuana plants in a home don't actually live in the residence.

"The reality is most people don't want to live with that odour and what's going on in the house," he said. "As to whether people end up actually using this marijuana for personal use, well I'm not entirely sure who's tracking that."

Pattenden added that such homes can also be a target for crime, attracting those who may want to steal marijuana.