Humans are smart but vulnerable. We need to be prepared for countless unforeseen events that could compromise our health and well-being. Toxicology arose as a way to understand, prevent, mitigate, and treat the potentially harmful consequences of many of the substances we are exposed to.
According to the Society of Toxicology (SOT) (http://www.toxicology.org/about/vp/vision.asp):
Toxicology is the study of the adverse effects of chemical, physical, or biological agents on living organisms and the ecosystem, including the prevention and amelioration of such adverse effects.
The National Library of Medicine's (NLM) Collection Development Manual elaborates by noting:
Toxicology studies the agents responsible for adverse effects, the mechanisms involved, the damage that may ensue, testing methodologies to determine the extent of damage, and ways to avoid or repair it. Toxicology is traditionally associated with chemical exposures, such as the effects of drugs, industrial chemicals, pesticides, food additives, household products, and personal care items. Toxinology, a sub discipline of toxicology, studies biological exposures, such as insect stings, poisonous mushrooms and plants, venomous snakes and aquatic life. The third category of toxicology is concerned with physical hazards, such as radiation and noise.
One of the key points to understand, as noted above, is that although toxicology in the popular mind is confined to chemicals and, probably, in practice most of the research and concern occur in this realm, other agents such as radiation and substances derived from biological organisms are equally relevant to the field.
The word toxicology is derived from the Latinized form of the Greek word toxicon, meaning “arrow poison.” Poison, as a noun, dates back to the Old French poison or puison, meaning, originally, a drink, especially a medical drink, but later signifying more of a magical potion or poisonous drink. Another point of terminology concerns the commonly misused term toxin. Despite past and informal uses of the term, it formally should be used to refer to toxic substances produced biologically. Thus, technically, chemicals such as formaldehyde or asbestos, say, would not be considered toxins. There are any number of other terms which could be used to delineate the broader category of substances which are toxic, regardless of origin. Examples are toxicant, toxic agent, and toxic substance. Xenobiotics is a term referring to substances, whether toxic or not, foreign to a given organism.
Finally, in this brief lesson on toxicology nomenclature, one needs to clarify the use of the words poisonous and venomous when used as animal adjectives. Though often used interchangeably, they are, in fact, rather distinct. A venom requires a delivery mechanism. Thus, because a snake, for example, injects its venom (or toxin) into its victim, it is considered a venomous animal. Instead, a toxic mushroom must be ingested to make its effect felt. Thus, it should instead be deemed poisonous.