The toxicity of poisons, toxins and venoms is measured by the median lethal dose of the substance needed to kill 50 per cent of those exposed to it. It’s known as the LD50, as in lethal dose, 50 per cent. The LD50 statistic is usually expressed in measures such as the number of grams of the poisonous substance per kilogram of a person’ s body weight.

Every substance is toxic if ingested in large enough quantities. For instance, water has an LD50 of 90. This means that, if a large number of people each weighing 100 kilos (220 pounds) each drank 9,000 grams (20 pounds) of water at one sitting, it would kill half of them.  Table Sugar has a LD50 of 29.7, Grain Alcohol is 7.06, Table salt is 3.0, THC is 1.2, caffeine is 0.19, nicotine is 0.05, cyanide is 0.0064 and strychnine is 0.001.

At the extreme-toxicity end of the scale, botulinum toxin has an LD50 estimated at about 0.000000001, or one-billionth of a gram per kilogram. This is the lowest LD50 generally recorded for any substance.  Botulinum toxin is a neurotoxin produced by the bacterium Clostridium botulinum that can cause the severe food poisoning known as botulism.

Marijuana is one of the less potent psychoactive drugs. It causes euphoria, disassociation and hunger. It can also cause your thought processes to become one long string of internal consistency moments (which may or may not be remembered once the effects wear off). Even very high doses won’t cause hallucinations in 99%   of the population. 

You wouldn’t know this from the common media representation of the drug. 

Teachers, parents, church officials are continuously tricked or cajoled into smoking up, or more likely eating a pot brownie. Five minutes later, they’re riding a unicorn through a rainbow, or arguing with the plants, or being chased by musical notes as if they’ve actually taken a powerful hallucinogen.

In this universe, marijuana is LSD. But why?

It seems to be based on the issue of creating a PG-rated drug experience. Mainstream writers, along with concerns of meeting broadcast standards, generally feel skittish about having their character use hard drugs. The resulting strategy is to either use an unnamed “substance” or depict a named drug, but with ridiculously overblown effects.

Even when the effects of LSD are shown, they are also powerfully overstated. On low doses, characters will experience detailed hallucinations and Daliesque delusions, when in reality a single tab of LSD will usually only give someone slight visual distortions that are easily distinguished from reality.