Practice Test GeeksABT - American Board of Toxicology Practice Test
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Environmental Toxicology Flashcards

6 cards from real ABT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. The EPA's Reference Dose (RfD) is defined as an estimate of daily exposure that:

    Answer: Is likely to be without appreciable risk of deleterious effects over a lifetime

    The RfD is an EPA estimate of daily oral exposure to a chemical that is likely to be without appreciable deleterious effects over a lifetime, used for non-carcinogens.

  2. Methylmercury exposure in humans primarily occurs through:

    Answer: Consumption of contaminated fish and seafood

    Methylmercury bioaccumulates in fish and seafood, making dietary consumption of large predatory fish (tuna, swordfish) the primary human exposure route.

  3. Which class of pesticides inhibits acetylcholinesterase and was originally developed as nerve agents?

    Answer: Organophosphates

    Organophosphate pesticides are structurally related to nerve agents and inhibit acetylcholinesterase, causing accumulation of acetylcholine at synapses.

  4. Lead exposure in children is most commonly associated with which source in older US homes?

    Answer: Lead-based paint chips and dust

    Lead-based paint used in homes built before 1978 is the most common source of lead exposure in US children through ingestion of paint chips and inhalation of dust.

  5. Dioxins (PCDDs) exert their toxic effects primarily through which molecular mechanism?

    Answer: Activation of the aryl hydrocarbon receptor (AhR)

    Dioxins bind with high affinity to the aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor that alters gene expression leading to diverse toxic effects.

  6. The 'cancer slope factor' (CSF) is used in risk assessment to estimate risk for which type of toxic endpoint?

    Answer: Linearized low-dose carcinogenicity risk

    The cancer slope factor (CSF) is used in the linearized multistage model to estimate the incremental lifetime cancer risk per unit of daily exposure for carcinogens.