Problems with Fentanyl
1. Very potent
2. Difficult to dilute powders , can have "hot spots" of high potency.
3. Can require higher dose of naloxone (Narcan), the antidote for opiates, higher than what is contained in Take Home Naloxone kits
4. Showing up in cocaine and other drug mixes.

For the first time, B.C. is on track for more than 1,500 deaths in a single year. Based on the first five months of 2017 data, B.C. will see 1,536 deaths by the end of this year.For more than seven months now, B.C. has seen an average of more than four overdose deaths every day. One quarter of new organ transplants are coming from overdose victims.
Averaging 4 deaths a day in BC.

1. Availability - can order online rather than shipping bulky product through Europe

2. Bigger profit margin than heroin

3. Extra potency is attractive to some.

4. Easy to snort, or take in tablets.

https://nowtoronto.com/news/why-is-fentanyl-showing-up-in-street-drugs-/

There have been no confirmed cases of marijuana contaminated with fentanyl, despite what Christie Clark and others have said.

Many other reasons not to buy street cannabis

https://www.vice.com/en_us/article/qv49a3/is-weed-really-being-laced-with-f...

90% of overdose deaths have been in those using alone.

Reagent tests and test strips are substance specific. They won't tell you all the contents, just if the one you are testing for is there.

Fentanyl test strips have two problems. There are many types of fentanyl, but the strips do not test for them all.
They have never been tested for applying to powders, they are meant for urine testing.

http://www.winnipegfreepress.com/breakingnews/sale-of-fentanyl-test-kits-st...

MAPS is working hard to have MDMA made available as a prescription medication

https://commons.wikimedia.org/wiki/File:2011_Drug_Harms_Rankings.svg

Which drugs should be legalized?

https://www.vox.com/policy-and-politics/2017/4/20/15328384/opioid-epidemic-...

a number of reasons why levamisole has become the number one cut. It's easy to mix with cocaine, has a similar "fish scale" appearance to high quality cocaine flake and gives the impression of having a greater volume than it actually possesses. It also gives a false positive in street tests for cocaine, so bulk buyers are not able to spot the cocaine has been cut, and is relatively cheap and easily available in bulk from cities across the Andean countries. According to an expert working for the UNODC in Colombia, the drug is regularly purchased at £32 per kilo in Bogota, Cali and Medellin, compared to £1,500 for a kilo of cocaine.

https://www.vice.com/en_dk/article/qbxwxp/levamisole-in-cocaine-900

About 10% of cocaine by volume. Can lead to agranulocytosis and blood vessel inflammation.