Several responses here:
- RE: Different drugs being "most addictive:" This is a function of personal brain chemistry and cannot be stated as an objective property of any substance. None of us are the same with respect to "baseline" (which is another fairytale state, but let's assume it exists for now) levels of endorphins, dopamine, seratonin, norepinephrine, and every other neurotransmitter in the book. Different drugs cause different changes in the apparent/perceived levels of these neurotransmitters, and depending upon the "baseline" brain chemistry of the user, one class of drug (e.g. opioids, stimulants, dissociatives, hallucinogens) is going to feel the most pleasurable and therefore will become the most reinforcing over a period of frequent use. For example, before my opioid habit got out of control, I found (and others agreed; none but me knew a controlled substance was involved) that I was a much "better" person after having taken a dose of an opioid. I was more productive, motivated, energetic, outgoing, compassionate, and happy (obviously). It was certainly not the stereotypical image that comes to mind when one imagines a nodding junky -- barely able to speak, uncoordinated, lethargic, etc. Perhaps the opioid was correcting an endorphin deficiency in my brain chemistry? Whether I go so far to claim "deficiency" or I just say that my natural brain chemistry made it likely that I would prefer opioids to other drug classes is beyond my own level of expertise/knowledge -- however, I can also say that I do not find stimulants (e.g. Amphetamines, cocaine) or benzodiazepenes (clonazepam, alprozalam, etc.) recreational in the least; they occasionally serve a purpose, but I feel no desire or compulsion to take them more often than, say, monthly; in fact it's usually a much greater amount of time between doses of such substances. But it'd be a snowy day in hell before I could honestly say that I didn't desire the effects that opioids had upon me once upon a time, before my addiction got out of control.
- Relative bioavailabilities of morphine vs. heroin: This is basic chemistry (fortunately -- my level of knowledge doesn't go much beyond basic!). Morphine has a low bioavailability both orally (10%) and nasally (30%) due to its failure to easily cross the blood-brain barrier. In fact, this property of Morphine was the reason Heroin was originally conceived and patented. By adding two acetyl groups to the Morphine molecule, it becomes much more lipophilic, and will cross the blood-brain barrier ~95% of the time. However, heroin itself is not even psychoactive -- it breaks down within minutes of ingestion into Morphine (which is, obviously, psychoactive) and 6-monoacetylmorphine (which, later, also breaks down into Morphine). So, the closer one can put it to his blood-brain barrier during ingestion, the more will have CROSSED the blood-brain barrier before it breaks down into Morphine. Oral consumption of heroin will result in the breakdown of nearly 100% of the heroin into morphine before it begins entering the bloodstream from the stomach/small intestine -- thus, ingesting heroin orally would be (assuming 100% purity) equivalent to ingesting the same amount of Morphine orally. Insufflation of heroin is much more likely to get it across the blood-brain barrier before it breaks down, since A) Substances are absorbed directly into the bloodstream across the mucous membranes in the sinuses and B) Very little is happening to the heroin which has yet to be absorbed in the relatively inert/dry sinuses of a healthy individual, so it will not begin the breakdown as rapidly as it would during oral ingestion. Obviously, IV injection of heroin allows it to rush the blood-brain barrier at near-100% quantities -- indeed, the famous IV heroin "rush" is the result of all of those non-psychoactive molecules suddenly breaking down into potent opioid molecules and agonizing the mu opioid receptors in the brain virtually simultaneously. This is why the "rush" of heroin is often judged subjectively superior to the use (even IV) of many/all other opioids by some users.
- "Toxicity" of Morphine and other first-generation opioids: The generation that first started using/becoming addicted to opioids in their pharmaceutical form (e.g. Morphine, Diacetylmorphine/heroin, Oxymorphone, Hydromorphone, etc., and Methadone, a synthetic opioid) has provided us with a generation's worth of data as to the long-term effects of said substances. There is absolutely NO evidence of ANY negative long-term effects resulting from the short- or long-term use of these substances across a relatively huge variance of dosage levels. When compared to various other substances generally considered "safe" on the long-term, opioids are clearly incredibly safe to use (at the proper dosage, frequency, and at pharmaceutical purity, with proper associated hygenic procedures). For example -- all of the OTC NSAIDs cause some sort of long-term organ damage (Aspirin: stomach; Acetaminophen: liver; Ibuprofen: kidneys; Naproxen: heart/stomach). Caffeine can cause high blood-pressure and heart disease (to say nothing of the dopaminergenic effects on brain chemistry). Nicotine: obvious. Alcohol actually IS a toxin; it can lead to blindness, it causes liver damage, heart disease, and high blood pressure. Cocaine/Amphetamines: High blood pressure, heart disease. Etc., etc. There have been countless cases of members of the medical profession who got "hooked" before the Harrison Narcotics Act of 1917 making opioids scheduled/controlled narcotic substances, remained addicted to several hundred milligram IV doses through WWI and WWII, and died of natural causes totally unrelated to opioid ingestion at old age.
The dangers associated with opioid use are entirely a product of their legal status. Improper/unhygenic manufacturing processes, toxicity/safety of "cut" material, improper/unhygenic transportation processes (I shudder these days to think about how I would happily shove into a needle and inject the contents of a wax bag that had been sitting in a sweaty dealer's pocket most of the day), and low availability of proper quantities of sanitary dosing equipment (e.g. needles, saline, alcohol pads, filters) all contribute to the high incidence of disease and fatality among opioid users today, to say nothing of the failure of our education system to properly inform them of the psychoactive effects of opioids, proper dosage, emergency procedures, etc., instead favoring a celebrate-the-ignorance "JUST SAY NO" approach (at least in the US).
If opioids were deregulated, and dependent users who could demonstrate their dependence were given unrestricted/lightly supervised access to the pure opioid and dosing mechanism of their choice, not only would said users stabilize at a dose which would allow them quality of life and stable functionality within capitalist society (proven in countless studies -- one of which happens to be known as Methadone Maintenance Treatment), but the black market demand for such substances would disappear pretty much overnight, causing availability to drop drastically and street prices to skyrocket, which would make first-time use incidences incredibly rare. Furthermore, medical complications arising from impurity, poor hygenics, poison, dirty/shared needles, contaminated tap water, etc. would disappear; with proper education as to dosage and emergency procedures, medical complications relating to opioid use would disappear altogether.
Anyway, enough of that pipedream.
- Uniformly white heroin (colloquially "China White," although this slang term sometimes refers to fentanyl or a fentanyl/heroin mixture) availability in the northeast US: During two years of addiction culminating in a 4 gram/day IV habit, I came across completely white (no trace of beige) powder that actually was heroin for the duration of approximately one week; maybe a total of three consecutive scores. It remains the best opioid experience I've had to date. At the time, I required anywhere from 5-7 bags in a shot for a recreational dose -- this stuff was fun at 2 bags and a party at 3; I wouldn't have done 4 for the sake of my own safety. I've done plenty of fentanyl; this wasn't it, and if it was IN it, there was very little of it -- this stuff definitely had a ~4 hour half-life and exhibited A) the heroin "rush" and B) a total lack of histamine-related pruritis (to which I was subject whenever I got a batch that had either been cut with morphine or had not been completely acetylized to heroin and contained morphine). At the end of this week, the dealer responsible for having tracked this stuff down (I don't want to give precise locations; let's just say it was a big city within a 2-hour radius of New York City) was arrested and remains in jail to this day. At the time of his arrest, he was borrowing a friend's car to which we had a spare set of keys, knew where it was parked, and in which there was found 80 bundles of this stuff -- in fact, that was the evidence at his trial for possession with intent. Sometimes I still daydream about deciding to take a look through my friend's car that evening.
So "China White" does exist here in the US, at least sometimes, but I can say that after having blown a good $100k+ on my habit, it was only in 3 ~$500 scores apiece. I've never heard it called "China White" except on Internet forums and maybe on the propoganda distributed by anti-drug resources -- we just called it really good dope. Rare, to be sure. Mostly I got the gray stuff lacey_k describes; sometimes I got more of a beige/brownish powder; and sometimes I got a much darker brown powder (which was usually quite weak, but now and then surprised me by being pretty damn good).
There were a few other times I received pure white powder after a score -- but all the rest of the times it was 100% fake, usually some combination of powdered sugar, flour, salt, sugar, and the like. One time earlier on in my naivete I blew around $4k on 23 grams of what turned out to be this kind of mixture. *sigh* Oh well. Those days are gone.
Anywhom, all the best.
dd