Ethanol withdrawal is also associated with severe morbidity and mortality (see Osborn, 2004). Nonetheless, the frequency of acute and chronic ethanol intoxication and the myriad complications that may result from or be associated with ethanol ingestion complicate the use and interpretation of the designation “ethanol poisoning” as it may pertain to the overall incidence of poisoning and drug overdose.

Illness from naturally occurring toxins derived from microorganisms can also lead to definitional confusion. Seafood-related toxins whose ultimate source was from microorganisms, such as those causing paralytic shellfish poisoning, are typically categorized as poisons. In contrast, bacterially derived toxins may or may not be categorized in this manner. In practice, the diagnosis and management of botulism, tetanus, and, more recently, anthrax, has been considered to be a form of “poisoning” relevant to the discipline of clinical toxicology, although these illnesses are not included in most epidemiological definitions of poisoning.

Lay definitions of poisoning are also relevant because they can drive health-care-seeking behavior and self-reporting of conditions, both of which can impact incidence estimates. Lay terms such as “food poisoning” (which could reflect an infectious gastroenteritis or a toxin-related condition), “poison oak” (a form of allergic contact dermatitis), and even “sun poisoning” (which could refer to sunburn or heat stroke) do not conform to biomedical concepts of poisoning, but may still be unavoidably captured in some incidence estimates.

Factors of intent, that is, whether an exposure occurred with the purpose of causing a toxic response, do not define poisoning per se, but these factors may impact how such events are reported. Defining adverse events associated with drugs of abuse is a particularly salient issue in this regard. For example, some events may or may not be categorized as a poisoning or drug overdose by health care providers, depending on whether the presenting medical complaint is viewed as an intended end-point effect.

Toxin exposure without an attributable and defined or discrete clinical effect presents yet another source of heterogeneous definitions. The absence of a documented clinical effect may reflect the true absence of a substantive exposure (e.g., a person seeking health care because of a potential for exposure to a toxin or because of exposure to a substance perceived to be dangerous by the lay public that has little or no actual toxicity); a subtle effect that may not be manifest by acute symptoms but may have serious long-term potential effects (e.g., a body burden of lead elevated above the population norm); or circumstances that do not allow determination of a causal relationship (e.g., postmortem carbon monoxide determination in a burn victim with both fire and smoke exposure). Although the standard definition of clinical poisoning does not include exposure without disease, the importance of these scenarios in terms of

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