Toxic Materials in the Body

A poison, or toxic substance, may be defined as a chemical that, in relatively small amounts, produces injury when it comes in contact with susceptible tissue. Clearly, the phrase “relatively small amounts” is less than precise, but this uncertainty is necessary because of the wide variance in the amount of each chemical needed to have an effect. A substance is generally not thought of as toxic if it is unreasonable to expect that a person would be exposed to the amount necessary to cause injury. A “susceptible” tissue is defined as that part of the body which is injured after exposure to that particular substance.