LC50
The standard toxicity test for chemical compounds is called the LD50. LD stands for Lethal Dose and 50 indicates 50 percent. In other words, LD50 means the lowest dose at which a material kills half of the test subjects.
The results are usually given in milligrams of compound per kilograms of body weight. Many of these tests are conducted on laboratory rats. To give you a few rat results: the LD50 of table sugar (sucrose) is 29,700 mg/kg. For table salt (sodium chloride, NaCl) it's 3,000 mg/kg. Really poisonous substances, though, measure in the single digits: Sodium cyanide (…