> I did not suggest that cannabis is harm free. I stated we cannot explicitly identified marijuana as the cause of illness.

Yes you did - using phrases like "there are no known health risks" you dismiss all the evidence we have that cannabis can cause harm.

Here's just one link, but there are many other reputable sources. This one discusses lung health.

http://www.nhs.uk/news/2012/06june/Pages/cannabis-lung-healt...

> The report says that the constituents of cannabis smoke are similar to those of tobacco smoke apart from the presence of THC (which is only in cannabis) or nicotine (which is only in tobacco). This means that cannabis smoke has the same carcinogens (substances that cause cancer) as tobacco smoke, although concentrations of these may be up to 50% higher. Like tobacco, cannabis also contains toxic carbon monoxide

Saying that this is equivalent to "no known health risks" is intellectually dishonest.