Recently there has been a lot of contaminated cannabis around the UK. I have bought blasted weed my self a couple of times and not noticed until I smoked it. Some contaminated weed is obviously sprayed, but some you can tell by looking at it. I have smoked cannabis that has been blasted, sprayed, contaminated or whatever you would like to call it. I only smoke this weed because I smoke weed everyday and there was a drought where I lived that lasted for about 3 weeks, and the only stuff around was cannabis sprayed with glass. I smoked about 3.5g of this weed in a day and for the next week I had a very soar throat and was constantly coughing up shit!
In the UK they spray cannabis with various things, some are worse than others but to be honest you do not want to be smoking any weed that has been contaminated in any way. I know that cannabis is sprayed with glass, usually very small fragments that you can not see with the eye. You can tell weed that has been sprayed with glass because the when you are smoking the spliff the ash is harder to knock off. I have seen weed that has been sprayed with melon juice or basically sugar. You can tell if cannabis is contaminated with sugar because it is usually dry the bud are very hard and if you eat some of it it taste very very sweet, I suppose you could use this cannabis for cooking if you were desperate. I also know of cannabis that has been sprayed with silica, the ash if a lit spliff of this also goes hard when smoked and it causes a very bag cough and soar throat.
In the UK there is a drought in the manufacture of cannabis, cannabis exports from the Netherlands to the UK had increased 300% in the last few months!
Where it is grown in the Netherlands the plants are sprayed usually with silica or glass about 1 week before harvest. This increases the crops weight by about 200%.