adolescent and adult exposures The most important difference between the pediatric and the adult profile by type of agent is in the higher percentage of cases in which psychopharmacologic drugs (sedatives, tranquilizers, and antidepressants) cause poisoning in adults and the much higher frequency of exposures to household and personal care products and plants in children There are seven basic routes of poison exposure: oral (ingestion), ocular, dermal, inhalational, transplacental, parenteral, and by envenomation Poisonings may result from acute or chronic exposures Most poisonings treated in EDs are acute, typified by the curious child who gains access to a medication or household cleaning product, or the suicidal adolescent who takes a polypharmaceutical overdose Chronic poisoning refers to toxicity which develops over time as a substance accumulates in the body, and is best exemplified by environmental exposure to lead or other heavy metals Chronic pharmaceutical toxicity also occurs Examples include acetaminophen hepatotoxicity in infants and small children after repeated supratherapeutic dosing, or aspirin poisoning in older adults with excessive dosing or renal impairment Chronic toxicity can be a challenging diagnosis because the source is not always apparent, the toxicity is not always clear, and the toxic process is not often obvious until serious clinical derangements occur In addition, serum drug levels not accurately reflect toxicity risk in chronic or acute-on-chronic exposures