Defining Poisoning

“All things are poison and not without poison; only the dose makes a thing not a poison”

Paracelsus (1493–1541)

There is no standard definition of poisoning that is universally accepted and applied in clinical practice, in data collection, and in public health policy settings.

Clinical Definition

Human poisoning subsumes any toxin-related injury. The injury can be systemic or organ-specific (e.g., neurological injury or hepatotoxicity). The source of the toxin can be a synthetic chemical or a naturally occurring plant, animal, or mineral substance. Thus poisoning can include the toxic effects of a classic toxin (e.g., cyanide), an overdose of a prescription medication (e.g., an antidepressant), an overdose of an over-the-counter preparation (e.g., headache tablets), or a complementary treatment (such as an herbal medicine or dietary supplement).

Classification Complexities

Disagreement over the classification of certain poisoning events leads to discrepancies in the estimates of poison-related mortality and morbidity; prominent among these disagreements are:

  • Exposures that fall in and out of various classification schemes (e.g., envenomation from a rattlesnake or black widow spider might be grouped with nontoxic bites).

  • Medical misadventure/adverse effects at therapeutic levels; medication responses that are not dose related but idiosyncratic, with or without allergic component.

  • Delayed versus acute toxic effects.

  • Illness from naturally occurring toxins derived from microorganisms (e.g., seafood-related toxins).

  • Toxic effects from ethanol (e.g., rapid ingestion, withdrawal, chronic).

  • Exposure to a potential toxin without a defined clinical effect (as when parents telephone a poison control center about a possible ingestion by their child).

The Committee’s Operational Definitions

To arrive at reasonable estimates of the magnitude of poisoning, the Committee adopted the definitions used by key federal health agencies and organizations that monitor poisoning in the population (see Chapter 3 for details).

  • Morbidity estimates used definitions from the National Interview Health Survey, National Ambulatory Medical Care Survey, National Hospital Ambulatory Care Survey, National Hospital Discharge Survey, and National Electronic Injury Surveillance Survey.

  • Exposure estimates were derived from the Toxic Exposure Surveillance System.

  • Mortality estimates used the classification of the National Center for Health Statistics.

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