Acetylcholine is the main neuro-transmitter that lets nerve cells communicate. But in larger doses this stuff will kill any mammal the same way it kills insects. It causes uncontrolled nerve firing in the brain. The disruption of normal nerve activity results in rapid failure of the body systems because they depend on nervous input for proper functioning. This stuff is particularly hazardous because it penetrates skin, eyes and mucous membranes readily.
Ingestion is slightly less hazardous as the liver has limited detoxifying action.
Once poisoning has occurred, treatment must happen quickly and include prolonged artificial respiration. Death is often the rapid result of poisoning by this insecticide. Once a recreational user is hooked on this drug, the substance is said by many authorities to be more addictive than cocaine or heroine. Millions of people worldwide are addicted to this substance. Billions of dollars are spent annually to buy it, advertise it, treat illnesses caused by it, and to help people break their addiction to it.