First off, to label something as medical isn't useful because there is no agency enforcing anything, or certification required, anyone can grow some herb, sell it to a dispensary and they can sell it as medical (the reasoning being that it's allowed to be sold under medical laws in those states). Dispensaries could come up with their own criteria for what they call 'medical', and some do, but again, without any sort of certification, or enforcement, it's just their word. Private organizations can do the same sort of certification, but again, then it's just their word. Then again, for things that really are legally regulated, say the FDA, can you trust their word? I'll come back to this theme, but in my mind this always boils down to trust (and a little education so you understand what info you get that you are expected to trust 
).
That said, your original question seems to be more concerned with a few of the finer points of growing. Before I give you what info I have (from many years of experience), I'd have to point you toward an author, Mel Frank who has written volumes on the subject, and is regarded by many as the expert. He partnered with Rosenthal on a new edition more recently, and their collaboration is really a bible, in my opinion.
Anyway, the question of organics vs non is really not as black and white as that. You have to understand that organics are typically not the substance your plants actually need, they are usually precursors. I will give you an example using nitorgen (one of the more necessary compounds we use ferts for). Organically nitrogen comes from living things breaking down. Plants contain a lot of it, and a leaf on the ground rotting is releasing that nitrogen, but it may be releasing it as, say, ammonia. Bacteria in the soil will consume this ammonia, and through a several stage process using diff types of bacteria, might convert it into a nitrate, a form of nitrogen that your plants can absorb and incorporate into their growing plans. On the other hand, you could use a more sterile environment, get a non-organic fert that will have soluble nitrogen that is immediately avail to the plant, and use that (this would be really common in hydro environments where you are staying much more sterile). Is one inherently bad? Usually organics are natural things like worm casings, manure, guano, and other types of waste, kinda gross to think about, but that's nature, and that's how it's been done for millions and billions of years. Is a soluble that's been isolated, or built, bad? That's something you'd really have to examine on a case by case basis. I personally don't mind using solubles, and discontinued pure organic within a year of trying them out. I go with brands I can trust (fox farm predominantly, but there are many awesome companies out there), and I read everything about how they are making their stuff. When in doubt you can always contact the company and get answers as well. Several brands have lines of organics as well, but I really haven't looked into them much, so can't really elaborate on that.
Any damage done by handling will be evident by sight, it's really not pertinent to what you are asking. Flushing doesn't really have anything to do with organics or solubles. Flushing has to do with nitrogen starving your plant, and pulling back on things like phosphate, and other building block materials. Though I'm sure this effects carcinogen content, the real reason people flush is because of the taste and harshness, two things that have nothing to do with health. This doesn't mean that bad things are being removed from the plant. For instance a plant which absorbed heavy metals wouldn't have less of them after a flush. Curing is the same. The cure, which follows the drying where the plant matter actually dies, is primarily responsible for breaking down unused sugar in the plant. Plants are basically big sugar producing machines. The take in nitrogen, from the air and soil, combine it with oxygen, and using sunlight, convert it to sugar. When it dies, your plant is full of the stuff! It hurts your lungs, and adds a plethora of very complex tastes which most smokers do not want. By severely elongating the period over which the plant looses its moisture, you allow the existing enzymes to continue breaking down these sugars into more simple compounds, and that, in a nutshell, is the primary process going on in a cure. There is also a small increase in thc content, little enough that most smokers wouldn't notice, and a conversion which raises the (I think) cbn to thc ratio slightly. Neither of these really have to do with organics vs solubles, the differences between those are primarily occurring before the plant has actually used the material.
I can't say that lacing doesn't happen, but it's basically a non-concern for people smoking anything close to high quality. I'm not going to elaborate, but if the guarantee of not being laced is all that med had going for it over black market, med wouldn't exist
In my mind the question is one of contamination. Solubles and organics are both safe in-and-of themselves, it's just a question of source, and speed. The big issue for me is that you have to be able to trust the source, be it your soil, ferts, drug dealer, dispensary, or caretaker. How do you know that your worm casings weren't grown in an area that had a lead hazzard tagged to the deed? Because you buy them from someone you trust! How do you know that the dolomite you just got wasn't stored in an area that was contaminated by mercury? Because you got it from someone you trust! Why do I pretty much stick with FF nutes? Because I trust them. Why do I grow my own? Because it's the only way I can truly know what's in what I consume, and it's the only way I can ensure my money isn't going straight into some criminals hands. I trust myself, and I know that I did my homework
Hope some of my ramblings were useful for ya
).That said, your original question seems to be more concerned with a few of the finer points of growing. Before I give you what info I have (from many years of experience), I'd have to point you toward an author, Mel Frank who has written volumes on the subject, and is regarded by many as the expert. He partnered with Rosenthal on a new edition more recently, and their collaboration is really a bible, in my opinion.
Anyway, the question of organics vs non is really not as black and white as that. You have to understand that organics are typically not the substance your plants actually need, they are usually precursors. I will give you an example using nitorgen (one of the more necessary compounds we use ferts for). Organically nitrogen comes from living things breaking down. Plants contain a lot of it, and a leaf on the ground rotting is releasing that nitrogen, but it may be releasing it as, say, ammonia. Bacteria in the soil will consume this ammonia, and through a several stage process using diff types of bacteria, might convert it into a nitrate, a form of nitrogen that your plants can absorb and incorporate into their growing plans. On the other hand, you could use a more sterile environment, get a non-organic fert that will have soluble nitrogen that is immediately avail to the plant, and use that (this would be really common in hydro environments where you are staying much more sterile). Is one inherently bad? Usually organics are natural things like worm casings, manure, guano, and other types of waste, kinda gross to think about, but that's nature, and that's how it's been done for millions and billions of years. Is a soluble that's been isolated, or built, bad? That's something you'd really have to examine on a case by case basis. I personally don't mind using solubles, and discontinued pure organic within a year of trying them out. I go with brands I can trust (fox farm predominantly, but there are many awesome companies out there), and I read everything about how they are making their stuff. When in doubt you can always contact the company and get answers as well. Several brands have lines of organics as well, but I really haven't looked into them much, so can't really elaborate on that.
Any damage done by handling will be evident by sight, it's really not pertinent to what you are asking. Flushing doesn't really have anything to do with organics or solubles. Flushing has to do with nitrogen starving your plant, and pulling back on things like phosphate, and other building block materials. Though I'm sure this effects carcinogen content, the real reason people flush is because of the taste and harshness, two things that have nothing to do with health. This doesn't mean that bad things are being removed from the plant. For instance a plant which absorbed heavy metals wouldn't have less of them after a flush. Curing is the same. The cure, which follows the drying where the plant matter actually dies, is primarily responsible for breaking down unused sugar in the plant. Plants are basically big sugar producing machines. The take in nitrogen, from the air and soil, combine it with oxygen, and using sunlight, convert it to sugar. When it dies, your plant is full of the stuff! It hurts your lungs, and adds a plethora of very complex tastes which most smokers do not want. By severely elongating the period over which the plant looses its moisture, you allow the existing enzymes to continue breaking down these sugars into more simple compounds, and that, in a nutshell, is the primary process going on in a cure. There is also a small increase in thc content, little enough that most smokers wouldn't notice, and a conversion which raises the (I think) cbn to thc ratio slightly. Neither of these really have to do with organics vs solubles, the differences between those are primarily occurring before the plant has actually used the material.
I can't say that lacing doesn't happen, but it's basically a non-concern for people smoking anything close to high quality. I'm not going to elaborate, but if the guarantee of not being laced is all that med had going for it over black market, med wouldn't exist
In my mind the question is one of contamination. Solubles and organics are both safe in-and-of themselves, it's just a question of source, and speed. The big issue for me is that you have to be able to trust the source, be it your soil, ferts, drug dealer, dispensary, or caretaker. How do you know that your worm casings weren't grown in an area that had a lead hazzard tagged to the deed? Because you buy them from someone you trust! How do you know that the dolomite you just got wasn't stored in an area that was contaminated by mercury? Because you got it from someone you trust! Why do I pretty much stick with FF nutes? Because I trust them. Why do I grow my own? Because it's the only way I can truly know what's in what I consume, and it's the only way I can ensure my money isn't going straight into some criminals hands. I trust myself, and I know that I did my homework
Hope some of my ramblings were useful for ya