A B.C.-based medical marijuana producer is recalling a batch of pot after finding that it was contaminated with mould. 

Whistler Medical Marijuana Corp. says it detected the mould in Lot 0004 of its White Widow strain of marijuana after two customers complained about its appearance. Anyone who received that batch of White Widow — which is also referred to as White Shark and Peace-Maker on the company's website — should stop using it, the company said. 

Health Canada, which licences marijuana producers under its Marihuana for Medical Purposes Regulations, says the company will send out appropriate packaging and a postage paid shipping container to anyone wishing to return the tainted product.

Health Canada says most mould does not present a significant health risk, but can cause infections in those whose immune systems have been weakened by serious illnesses.

"If clients wish to destroy the product at home, they should add water to the marijuana to render it unusable, mix it with cat litter to mask the odour and dispose of it with regular household waste," Health Canada said in a written statement.

Neither the company nor Health Canada have received any reports of adverse reactions from use of the mouldy batch.

This is the third recall of medical marijuana since Health Canada radically changed the rules on April 1, moving approved production from a cottage industry of thousands of loosely regulated growers to a commercially competitive sector.

On April 18, Health Canada recalled a batch of Purple Kush from Greenleaf Medicinals of B.C. due to manufacturing irregularities.

Peace Naturals Project voluntarily recalled a batch of marijuana May 9 when it tested positive for bacteria exceeding acceptable limits.