As Breaking Bad has taught us, the clandestine manufacture of methamphetamine is a very dangerous undertaking. It involves the use of many harmful substances, which depending on the synthesis method include highly corrosive acids and bases, cancer-causing benzene, brain-damaging mercury and lead, jaw-wrecking phosphorus, and blood-breaking sodium cyanide. Blending these various substances together can produce noxious fumes, making gas masks and chemical suits a necessity if you want to avoid getting seriously hurt.
Meth cooks, at least those involved in small scale operations, tend not to be trained chemists. If they don't follow the correct recipe, either because they lack the necessary knowledge or skill, or they just don't care, the aforementioned harmful substances can end up in the final product. Lead is a particularly dangerous meth contaminant. A batch of meth responsible for an outbreak of acute lead poisoning in Oregon in 1988 was found to contain >60 percent lead by weight, which is nuts! If meth is synthesized using crushed tablets of pseudoephedrine, granules from the tablets can make their way into the veins of intravenous users, causing skin irritation and the increased likelihood of nasty bacterial infections. Meth can also be contaminated with organic compounds closely related to something called alpha-benzyl-N-methylphenethylamine, which when tested in mice proved to be more potent inducers of seizures compared to meth.
|Sidewalk chalk is occasionally added to meth (Source)|
In addition to the nasty stuff inadvertently introduced into a batch of meth during its manufacture, an interesting collection of substances are used to dilute meth prior to selling it (got to maximize those profits). These are known to include sugars such as lactose and mannitol (cheap way to add bulk), methylsulfonylmethane (physically resembles meth, improving the perceived quality of the drug), mild stimulants such as caffeine and ephedrine (mimic the effects of meth), and sidewalk chalk (used to provide a splash of colour).
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