Thanks for the opportunity to get at least some of this information "in print"!
Frustratingly, I didn't bookmark/save all the documentation about the various percentages of THC in cannabis over the years, but I recall it was relatively easy to find...and this is not something that you should have a difficult time convincing anyone of (because any toker worth his/her weight in rolling papers KNOWS they're always trying to score the weed with the highest THC, and the different hybrids vary substantially). The THC level is what determines the 'going rate/price' per ounce (for connoisseur's, varying CBD levels, and low CBN levels also command a higher price)...but the main issue is generally THC.
There are pro-cannabis sites that say it's a myth (and a "scare tactic" of sorts) that the THC levels have risen over the years (same ones that say it's not harmful or addictive)...but anybody with even a 1/8 ounce of common sense knows that the major producers & 'minor hobbyists' have been cross-hybridizing and developing stronger & more potent strains for decades. Or you can talk to an OLD hippie (that isn't mush-brained) and discern the truth...the old rule of thumb used to be that a quarter ounce (7 grams without seeds or stems), should produce 5-7 joints - each having the diameter of an adults middle finger (a minimum of one gram each). That's because it took that much (several doobies passed around amongst friends) to get the same buzz that you can get now from a couple hits off a pinner (skinny lil' joint), a one hitter or a pipe.
Onward...
Below are several links that explain it all more scientifically & completely. In a nutshell, we have these baseline negative health realities:
-Even though it feels like one is getting a much better (more sound) sleep after toking, the fact is that it disrupts sleep/dream patterns substantially, resulting in greater lethargy upon wakening and throughout the day (actually several days). Cannabis shortens REM duration & decreases eye movement (in animals it's been found to totally stop the REM cycle. It also shortens and degrades the SWS cycle (slow wave sleep).
-Cannabis is more than just psychologically addictive - it IS physically addictive. Physical withdrawal symptoms are generally worst days 2-10/14, and can last (in various levels & extremes) for a month or more. Withdrawal symptoms include:
-- temperature fluctuations (typically night sweats, sometimes brutal)
-- low grade 'flu-like' symptoms (some experience fairly strong nausea & diarrhea)
-- extremely vivid dreams & restless sleep/insomnia (from having sleep/dream patterns return to normal)
-- lack of appetite - weight loss
-- various levels of anxiety
-- heart arrhythmia
-- irritability
-- lethargy, tiredness/weakness, yawning, compromised psychomotor skills and hypersomnia (from the lack of sound sleep & vivid dreams caused by withdrawal, the craving to catch up on sleep can be enormous).
--It increases heart rate (sometimes substantially, generally 20-50 beats per minute, but can double heart rate)
--It lowers body temperature
--The tar from smoking unfiltered weed is substantially more than cigarettes (in fact, the tar from one 'real' joint (see below) is approximately equal to that from a whole pack of filtered cigarettes). I've seen dopers argue this, but never after testing it. To test it, take a white paper towel & fold it in fourths, then put it over your mouth and exhale completely through the towel (a filtered cigarette and a full/real joint). The difference between a full cigarette and a joint is 'crazy obvious'.
Then there's the neurochemistry (you can find the details in the various links below). Here's the basic way I explain that one becomes psychologically addicted and "altered" --
Imagine all brain chemicals & receptors have a normal range of 0-10. At zero, we feel the most, emotionally flat/dead, most dumb, most clumsy, least motivated & most depressed that is possible to feel. At 10 we feel the happiest, most creative, most vibrant/alive, crispest & highly coordinated, and most joyful that is possible. When one ingests/inhales cannabis (or any other addictive substance), the natural scale is totally 'blown'...now one can experience joy, creativity, vibrancy (and other "attributes" of weed) at a level of say, "plus 15". And conversely, when it wears off, the pendulum now can swing to a "negative 5". Do that once - and it's not really all that big of a deal...just some rebound flatness, lethargy and slight depression that fades over a few days. It all fades EXCEPT the memory of that wonderful feeling - a state that's impossible to attain without the drug.
Do it one or two times weekly for a couple-three months, and one typically finds themselves fairly sluggish, dulled & flat throughout the week...usually without realizing it, or it's chalked up to something else. (Of course! - because we've been thoroughly conditioned to believe "it's natural & harmless"...and we certainly don't WANT to believe anything else. And no one is experiencing the negative effects at any measurable/discernable level at this point). Think alcohol - who experiences the symptoms of mental & liver damage after drinking for a few months? Nobody thinks they are experiencing it, but everybody DOES experience it.
Remember, that brain-chemistry pendulum has been continually forced out of it's normal range (from 0-10) to a +15, so now what used to feel wonderful at a natural level of 7-9, now feels like a 4-6 (or actually IS a 4-6 because the rebound swing went lower than 0)...and to reach that 7-9 feeling again? Yep, one HAS to hit the smoke. This is not "emotional" or "mental" - what is 'felt emotionally' is a result of a true biological & physiological alternation.
Smoke daily for a few months/years? Most people 'lose the reality' of what they used to feel like, and find they simply cannot enjoy life 'naturally' until they've quit completely and given themselves several months for their neurochemistry to rebalance (something that is VERY unlikely to happen). I used to have data that showed that of all the drugs, the percentage of pot smokers that ever become totally clean is the lowest. Very few have the courage/willpower or understanding to deal with it (for many reasons, one of the biggest is because it generally means having to restructure one's complete social life away from their toking friends...except for the pitiful "loner stoners" of course).
Oh yes, the majority of daily tokers can hold a stable job, go to college, pull decent grades (if they haven't smoked for years and suffered the memory-motivation loss/damage)...but after a few months, you'll virtually ALWAYS find them scheduling their 'fun activities' for when they're high (otherwise, the activities are just not 'as fun'). And coming from someone that's been there, I can tell you truly...it takes years to be able to really "jam out" to your favorite tunes again, and experience the same level of pleasure & creativity in certain activities & pursuits (particularly sex and "art"). There's just no way to push that neurochemistry to a 15 when it's natural peak level is a 10 ...but after you've toked for any substantial length of time, you always remember how the 15 felt...and even a 'strong 10' will never be the same for decades (or for the rest of your life) :(
The chart/table below is very accurate - however, since it's from a 'government site' http://www.drugabuse.gov/researchreports/marijuana/marijuana3.html you won't likely have much success at impressing a stoner, since they generally believe the government's intent is to villainize cannabis (that's the 'double sting' thing I mentioned in my original post). But if you Google the issues separately, you'll find AMPLE independant research that validates the data in the table below. (Also note, I did see several inaccuracies in the data on this site - so be sure to double/triple verify if you plan to quote from it - the table is very accurate as far as I can tell.
Marijuana's Effects on the Brain
When marijuana is smoked, its active ingredient, THC, travels throughout the body, including the brain, to produce its many effects. THC attaches to sites called cannabinoid receptors on nerve cells in the brain, affecting the way those cells work. Cannabinoid receptors are abundant in parts of the brain that regulate movement, coordination, learning and memory, higher cognitive functions such as judgment, and pleasure.
Brain Region
Functions Associated With Region
Brain regions in which cannabinoid receptors are abundant
Cerebellum
Body movement coordination
Hippocampus
Learning and memory
Cerebral cortex, especially cingulate, frontal, and parietal regions
Higher cognitive functions
Nucleus accumbens
Reward
Basal ganglia
Substantia nigra pars reticulata
Entopeduncular nucleus
Globus pallidus
Putamen
Movement control
Brain regions in which cannabinoid receptors are moderately concentrated
Hypothalamus
Body housekeeping functions (body temperature regulation, salt and water balance, reproductive function)
Amygdala
Emotional response, fear
Spinal cord
Peripheral sensation, including pain
Brain stem
Sleep and arousal, temperature regulation, motor control
Central gray
Analgesia
Nucleus of the solitary tract
Visceral sensation, nausea and vomiting
Here's the list of very informative links from which you can compile data. The one thing to note is that some of the research has been done with Marinol (or other "unnatural" forms of the THC). While the effects may be similar, they are not the same...so be careful of that.
The one thing these links are missing (as well as this post) is the data on substantial memory/motivation loss in long term use. I've been working on re-compiling this data (below) for a few hours, and I just don't have the time to compile any more. Here's a general Google search on "cannabis + memory OR motivation + "cannabinoid receptors" http://tinyurl.com/ybvmtys - you'll find tons of valid info in the results.
In closing (for everyone reading) - I am 50 years old, Rocky is 56 - we have both seen our fair share of friends & acquaintances whose lives, dreams, potential and health have been adversely affected by using marijuana. We have both smoked ourselves - I have been very harmfully addicted and overcome it...twice (I've basically lost eight years of my life - not to mention the loss of health, money, potential and things I could have accomplished or possessed); it's harder to gauge how Rocky has been adversely affected because he smoked much lighter, but much longer. Whether one chooses to believe it or not, this substance is as serious (and possibly more insidious) than any other addiction. Hence if you'd like to share how you (or those you know/have known) have been adversely affected or ask questions about aspects of cannabis usage you don't understand, that is welcome and encouraged. However, if you'd like to debate this topic (whether it's harmful or addictive...or justify it's use), there are other forums for that. If you post wisecracks or "poke fun" about a subject matter that is not funny, you'll find your posts deleted. And yes, I am quite aware that cannabis has legitimate uses, but one of my criteria for herbal choice & usage (just like Dr. Christopher) is that it should not be addictive (and if an herb or substance is in any way capable of being addictiing or causing harm, the only justification for it's use is if there is no alternative).
