chemicals! weed usually doesnt have any additives.

Weed is a natural plant... The others are man made combinations of otherwise deadly stuff.

Because weed doesnt break down muscle tissue like the others.

those are hard drugs a bunch of chemicals put together weed if just a plant

weed is classified as a nutural or "plant" while crack, heroine,etc. are counted as man made or "chems"

ooooooohhh ok i get it now..thanks guys/gals

this aint an answer anybody'll like but..weed has hundreds of different chemicals(cannabanoids)in it that scientists have no specific knowledge of their effect, carcinogenic or not. crack has few. thats why it leaves no residue (melts in to liquid and evaporates into gas immediately) if its good blow, and u cook it urself. The cooking boils out all the "cut". i smoke on ashes, not brillo, and its the cleanest, purest taste in the world. i love pot too tho

do you really need to ask? METH- The most disturbing sign of meth addiction is the classic meth-user look of a wounded face and a collapsed jaw. Because Meth is a super Sudafed, it dries out the skin completely. Addicts begin to believe they are suffering from “meth lice”. This leads to frantic scratching of the face using fingernails – a process generally known as picking. Picking can lead to serious self-inflicted wounds, especially in the face. Another physical sign is rotten teeth and a collapsing jaw. Meth dries out the gum completely and leads to the grinding of the teeth and the jaw collapsing inward. Other physical symptoms include a flushed appearance, severe weightloss, boundless energy, deep sleep and excessive sweating. On an emotional level, the effects of a meth addiction can be equally visible and devastating. Some of the emotional signs of meth abuse include irresponsibility, child neglect, and crime (to pay for the drug). A single puff of meth can keep a user high for 24 hours, unlike cocaine or heroin which only last for a couple of hours. For someone on the mend or looking to sustain the habit, this can lead to serious bouts of violence, paranoid schizophrenia and suicidal tendencies. HERION- Long-term effects of heroin appear after repeated use for some period of time.Chronic users may develop collapsed veins, infection of the heart lining and valves, abscesses, cellulites, and liver disease. Pulmonary complications, including various types of pneumonia, may result from the poor health condition of the abuser, as well as from heroin's depressing effects on respiration.In addition to the effects of the drug itself, street heroin may have additives that do not really dissolve and result in clogging the blood vessels that lead to the lungs, liver, kidneys, or brain. This can cause infection or even death of small patches of cells in vital organs. With regular heroin use, tolerance develops. This means the abuser must use more heroin to achieve the same intensity or effect. As higher doses are used over time, physical dependence and addiction develop. With physical dependence, the body has adapted to the presence of the drug and withdrawal symptoms may occur if use is reduced or stopped. Withdrawal, which in regular abusers may occur as early as a few hours after the last administration, produces drug craving, restlessness, muscle and bone pain, insomnia, diarrhea and vomiting, cold flashes with goose bumps ("cold turkey"), kicking movements ("kicking the habit"), and other symptoms. Major withdrawal symptoms peak between 48 and 72 hours after the last does and subside after about a week. Sudden withdrawal by heavily dependent users who are in poor health can be fatal. MARIJUANA- Scientists have learned a great deal about how THC acts in the brain to produce its many effects. When someone smokes marijuana, THC rapidly passes from the lungs into the bloodstream, which carries the chemical to the brain and other organs throughout the body. THC acts upon specific sites in the brain, called cannabinoid receptors, kicking off a series of cellular reactions that ultimately lead to the “high” that users experience when they smoke marijuana. Some brain areas have many cannabinoid receptors; others have few or none. The highest density of cannabinoid receptors are found in parts of the brain that influence pleasure, memory, thoughts, concentration, sensory and time perception, and coordinated movement.1 Not surprisingly, marijuana intoxication can cause distorted perceptions, impaired coordination, difficulty in thinking and problem solving, and problems with learning and memory. Research has shown that marijuana’s adverse impact on learning and memory can last for days or weeks after the acute effects of the drug wear off.2 As a result, someone who smokes marijuana every day may be functioning at a suboptimal intellectual level all of the time. Research on the long-term effects of marijuana abuse indicates some changes in the brain similar to those seen after long-term abuse of other major drugs. For example, cannabinoid withdrawal in chronically exposed animals leads to an increase in the activation of the stress-response system3 and changes in the activity of nerve cells containing dopamine.4 Dopamine neurons are involved in the regulation of motivation and reward, and are directly or indirectly affected by all drugs of abuse. Addictive Potential Long-term marijuana abuse can lead to addiction; that is, compulsive drug seeking and abuse despite its known harmful effects upon social functioning in the context of family, school, work, and recreational activities. Long-term marijuana abusers trying to quit report irritability, sleeplessness, decreased appetite, anxiety, and drug craving, all of which make it difficult to quit. These withdrawal symptoms begin within about 1 day following abstinence, peak at 2–3 days, and subside within 1 or 2 weeks following drug cessation.5 Marijuana and Mental Health A number of studies have shown an association between chronic marijuana use and increased rates of anxiety, depression, suicidal ideation, and schizophrenia. Some of these studies have shown age at first use to be a factor, where early use is a marker of vulnerability to later problems. However, at this time, it not clear whether marijuana use causes mental problems, exacerbates them, or is used in attempt to self-medicate symptoms already in existence. Chronic marijuana use, especially in a very young person, may also be a marker of risk for mental illnesses, including addiction, stemming from genetic or environmental vulnerabilities, such as early exposure to stress or violence. At the present time, the strongest evidence links marijuana use and schizophrenia and/or related disorders.6 High doses of marijuana can produce an acute psychotic reaction; in addition, use of the drug may trigger the onset or relapse of schizophrenia in vulnerable individuals. What Other Adverse Effect Does Marijuana Have on Health? Effects on the Heart Marijuana increases heart rate by 20–100 percent shortly after smoking; this effect can last up to 3 hours. In one study, it was estimated that marijuana users have a 4.8-fold increase in the risk of heart attack in the first hour after smoking the drug.7 This may be due to the increased heart rate as well as effects of marijuana on heart rhythms, causing palpitations and arrhythmias. This risk may be greater in aging populations or those with cardiac vulnerabilities. Effects on the Lungs Numerous studies have shown marijuana smoke to contain carcinogens and to be an irritant to the lungs. In fact, marijuana smoke contains 50–70 percent more carcinogenic hydrocarbons than does tobacco smoke. Marijuana users usually inhale more deeply and hold their breath longer than tobacco smokers do, which further increase the lungs’ exposure to carcinogenic smoke. Marijuana smokers show dysregulated growth of epithelial cells in their lung tissue, which could lead to cancer;8 however, a recent case-controlled study found no positive associations between marijuana use and lung, upper respiratory, or upper digestive tract cancers.9 Thus, the link between marijuana smoking and these cancers remains unsubstantiated at this time. Nonetheless, marijuana smokers can have many of the same respiratory problems as tobacco smokers, such as daily cough and phlegm production, more frequent acute chest illness, and a heightened risk of lung infections. A study of 450 individuals found that people who smoke marijuana frequently but do not smoke tobacco have more health problems and miss more days of work than nonsmokers.10 Many of the extra sick days among the marijuana smokers in the study were for respiratory illnesses.

Because God made weed, and I'm too pretty for him to make me ugly like that.