When living in Paris in 2006, I had a terrible experience with the infamous contaminated weed called "gritweed" in the UK. While studying at a university in the French capital, I smoked cannabis with friends, like many students do. The hashish was so weak it was almost certainly adulterated, so I avoided that. For the first year, good quality marijuana would be readily available.

Then, sometime in 2006, a white powder started appearing on the pot. Noone knew what it was, and most people would just say that "it has a lot of crystals" or that "it is just the bottom of the bag". I felt something was wrong, so I complained a lot about it. All the other students tried to defend their purchase, and even accused me of being paranoid. They saw my skepticism as an attack on their hustling skills.

But I was right. Because a year after the awful stuff appeared, French news could report that the cannabis was indeed contaminated, and not with the benevolent substances such as flour, that we had thought, but with super-fine silica powder. The French government issued a health warning, and even started a government helpline for people to call. I now understood why I had such a terrible cough, and a constant throat inflammation. No wonder. I had been inhaling contaminants that were in no way safe.

I got really scared, and saw a doctor. I was referred to a lung specialist. The doctor who referred me did not know about gritweed, and was thankful for the information I gave her. The lung specialist, however, mocked me, saying he did not understand why anyone would inhale any smoke at all. But he did refer me to several other specialists. I did extensive lung tests, in the form of x-rays, breathing tests, and even a CAT scan. They did find some scarring in the airways, but it was impossible to tell what might have caused it. Some people are born like that, according to the doctor. In any case, the inflammation and cough I had was real, and there were reports of serious harms from this stuff coming in from both France and the UK.

Oh, and the women who did the CAT scan recommended I smoke "beuh" (French slang for weed), instead of hash. When I told them my problems actually stemmed from "beuh", however, one of them was shocked, and the other doctor made fun of her, saying "do you smoke beuh, or what?". She probably did.

Some of my friends were pointing out that the French government just had a series of raids on cannabis factories leading up to the occurence of gritweed. So this is what such raids leads to - because the people who run these factories need to get their money anyway, don't they? If criminals can increase product weight and earn more money in the short run, without much added risk, of course they will do it. This is what happens in an illegal market.

I am deeply shocked. It took the government a whole year to issue warnings, and even then I would say only about 20% of my friends would stop using cannabis. It is completely unacceptable in a democracy to put millions of people at risk.

Cannabis has been around me in my circle of friends my whole life, and all my friends have grown up to become normal, responsible adults. Many still enjoy it on occasion. Yet, noone talks about it: the power of the taboo and the illegality is so strong that it is difficult to handle emergency health hazard situations like this.

Cannabis users deserve the same rights as others. The whole situation made me an activist for harm reducation and regulation. I pressured the student union to put up warning posters, which were subsequently ripped down, perhaps by the administration. A good drug user, is a sick or dead drug user, apparently, for some people. But I will not be silenced.

To this day, I am afraid for my health. Afraid that the grit could have hurt my lungs or body. I quit smoking at once when I found this out, of course, but having unknowingly used it for a long time, I am not sure how it will affect me. I can only hope that my body takes care of it, and hope for the best.

Apparently the appalling stuff is still around. Dealers have gotten better at hiding the contaminants. This weed has been dubbed "stealth grit". Sometimes contamination can be undetectable to the naked eye. But chewing and tasting a tiny piece of weed should still work in detecting it. If it crackles when you chew it, it has silica powder. If it tastes sweet, sugar water. If it tastes chemical, some other contaminant. Chewing pure pot should be like chewing salad, and it should have a mildly bitter taste of plant material. Another good indication would be abonormally high weight compared to physical size.

Be safe.

More information on contaminated cannabis:

ITV Wales report on gritweed in two parts.

Health warning from UK government.

Soapbar - contaminated hashish.