ABSTRACT
In essence, toxicology is the science of poisons, toxicants, or toxins. A poison, toxicant, or toxin is a substance capable of causing harm when administered to an organism. Harm can be defined as seriously injuring or, ultimately, causing the death of an organism. This is a rather simplistic definition, because virtually every known chemical or substance has the potential for causing harm. The term
toxicant
can be a synonym for
poison
, or the term
poison
might be more appropriate for the most potent substances, i.e., substances that induce adverse effects at exposure levels of a few milligrams per kilogram of body weight (see later discussion). The term
toxin
usually refers to a poison derived from a protein or conjugated protein produced by some higher plant, animal, or pathogenic bacteria that is highly poisonous for other living organisms, e.g., botulinum toxins. Toxicologists study the noxious or adverse effects of substances on living organisms or on
in vitro
surrogate models, such as cell and tissue cultures. The substances toxicologists study are usually chemical compounds but may be elemental or complex materials. Radioactive elements, heavy metals (e.g., mercury or lead), or the packing materials used in food processing are examples of such substances. Food toxicology deals with substances found in food that might be harmful to those who consume sufficient quantities of the food containing such substances. On rare occasions, common foods are contaminated with unacceptably high levels of toxicants. Such substances can be inherent toxicants, substances naturally found in foods, or contaminants, which are substances that find their way into food either during the preparation or processing of such foods.
