Sum of adverse effects or the degree of danger posed by a substance to living organisms. It is expressed generally as a dose response relationship involving the quantity of substance to which the organism is exposed and the route of exposure skin (absorption), mouth (ingestion), or respiratory tract (inhalation). Toxicity is classified usually as (1) Acute: harmful effects produced through a single or short-term exposure. (2) Chronic: harmful effects produced through repeated or continuous exposure over an extended period. (3) Subchronic: harmful effects produced through repeated or continuous exposure over twelve months or more but less than the normal lifespan of the organism.