In the U.S., the FDA requires an extensive process to determine drug efficacy and safety before marketing is permitted. Hence, the probability of adverse effects from use of these agents is very small. Therefore, the probability of adverse effects from sufficiently high exposures tends to be much greater. The potential for a toxicant to cause carcinogenic effects is assessed by observing its ability to generate tumors in animal test systems. Non-carcinogenic effects include all toxic effects other than the generation of cancer.
Acute effects are adverse effects that occur immediately or shortly after exposure to a toxicant.
Chronic effects occur after some delay or after a long period of chronic exposure. Beware of confusion resulting from these homographs. Acute and chronic refer both to duration or time of onset of effects and to duration of exposure. Although the words are the same, the meanings differ. Target organs are the specific organs or tissues adversely affected by a particular toxicant.