If you'd like to begin knowing atleast a little bit about what try to come off knowing. You can start with these links.
http://www.jackherer.com/chapters.html
http://www.norml.org/index.cfm?Group_ID=3475
There have been NUMEROUS studies showing that there are little if any negative side effects of marijuana.
Please read, and stop posting stuff YOU KNOW NOTHING ABOUT.
Some copy and paste.
Myth: One Joint Equals One Pack (or 16, or maybe just 4) Cigarettes
Some critics exaggerate the dangers of marijuana smoking by fallaciously citing a study by Dr. Tashkin which found that daily pot smokers experienced a "mild but significant" increase in airflow resistance in the large airways greater than that seen in persons smoking 16 cigarettes per day.1 What they ignore is that the same study examined other, more important aspects of lung health, in which marijuana smokers did much better than tobacco smokers. Dr. Tashkin himself disavows the notion that one joint equals 16 cigarettes.
A more widely accepted estimate is that marijuana smokers consume four times as much carcinogenic tar as cigarettes smokers per weight smoked.2 This does not necessarily mean that one joint equals four cigarettes, since joints usually weigh less. In fact, the average joint has been estimated to contain 0.4 grams of pot, a bit less than one-half the weight of a cigarette, making one joint equal to two cigarettes (actually, joint sizes range from cigar-sized spliffs smoked by Rastas, to very fine sinsemilla joints weighing as little as 0.2 grams). It should be noted that there is no exact equivalency between tobacco and marijuana smoking, because they affect different parts of the respiratory tract differently: whereas tobacco tends to penetrate to the smaller, peripheral passageways of the lungs, pot tends to concentrate on the larger, central passageways.3 One consequence of this is that pot, unlike tobacco, does not appear to cause emphysema.
Myth: Pot Kills Brain Cells
Government experts now admit that pot doesn't kill brain cells.1 This myth came from a handful of animal experiments in which structural changes (not actual cell death, as is often alleged) were observed in brain cells of animals exposed to high doses of pot. Many critics still cite the notorious monkey studies of Dr. Robert G. Heath, which purported to find brain damage in three monkeys that had been heavily dosed with cannabis.2 This work was never replicated and has since been discredited by a pair of better controlled, much larger monkey studies, one by Dr. William Slikker of the National Center for Toxicological Research3 and the other by Charles Rebert and Gordon Pryor of SRI International.4 Neither found any evidence of physical alteration in the brains of monkeys exposed to daily doses of pot for up to a year. Human studies of heavy users in Jamaica and Costa Rica found no evidence of abnormalities in brain physiology.5 Even though there is no evidence that pot causes permanent brain damage, users should be aware that persistent deficits in short-term memory have been noted in chronic, heavy marijuana smokers after 6 to 12 weeks of abstinence.6 It is worth noting that other drugs, including alcohol, are known to cause brain damage.
Myth: Marijuana Causes Sterility and Lowers Testosterone
Government experts concede that pot has no permanent effect on the male or female reproductive systems.1 A few studies have suggested that heavy marijuana use may have a reversible, suppressive effect on male testicular function.2 A recent study by Dr. Robert Block has refuted earlier research suggesting that pot lowers testosterone or other sex hormones in men or women.3 In contrast, heavy alcohol drinking is known to lower testosterone levels and cause impotence. A couple of lab studies indicated that very heavy marijuana smoking might lower sperm counts. However, surveys of chronic smokers have turned up no indication of infertility or other abnormalities.
Less is known about the effects of cannabis on human females. Some animal studies suggest that pot might temporarily lower fertility or increase the risk of fetal loss, but this evidence is of dubious relevance to humans.4 One human study suggested that pot may mildly disrupt ovulation. It is possible that adolescents are peculiarly vulnerable to hormonal disruptions from pot. However, not a single case of impaired fertility has ever been observed in humans of either sex.
Myth: Pot Causes High Blood Pressure
According to the NATIONAL ACADEMY OF SCIENCES, the effects of marijuana on blood pressure are complex, depending on dose, administration, and posture.1 Marijuana often produces a temporary, "moderate" increase in blood pressure immediately after ingestion; however, heavy chronic doses may slightly depress blood pressure instead. One common reaction is to cause decreased blood pressure while standing and increased blood pressure while lying down, causing people to faint if they stand up too quickly. There is no evidence that pot use causes persisting hypertension or heart disease; some users even claim that it helps them control hypertension by reducing stress.
One thing THC does do is to increase pulse rates for about an hour. This is not generally harmful, since exercise does the same thing, but it may cause problems to people with pre-existing heart disease. Chronic users may develop a tolerance to this and other cardiovascular reactions.
