In 2010 Alexandra Datig found several very harmful fungi associated with marijuana. The growth of cannabis indoors poses a great problem as it provides ideal conditions for the growth of these organisms. The three most dangerous strains of aspergillis, fumigitus, flavus and niger exist naturally on the plant. A deadly alfa-toxin can be associated with these strains. A 1996 study of 10,000 patients with invasive aspergillis, at Winchester Hospital in the UK, saw the cost per patient to treat or cure the disease rose to $63,000, for a total in costs of $633 million.

Coloradans residents over age 21 are permitted to grow up to six marijuana plants in their homes for personal use.  Plants have to be grown in a locked location, not in a garden or yard. Both counties and municipalities can pass stricter laws. It will be interesting to see what happens in CANADA