Practice Test GeeksABT - American Board of Toxicology Practice Test
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Reproductive and Developmental Toxicology Flashcards

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  1. Which period of prenatal development is most sensitive to teratogenic agents causing structural malformations?

    Answer: Weeks 3–8 (organogenesis)

    The embryonic period (weeks 3–8), when organogenesis occurs, is the most sensitive window for structural teratogenesis because organ rudiments are being established.

  2. Thalidomide caused phocomelia (limb reduction defects) when taken during which gestational window?

    Answer: Days 27–40

    Thalidomide causes limb reduction defects (phocomelia) when exposure occurs during days 27–40 of gestation, coinciding with limb bud development.

  3. The Reproductive and Developmental Toxicant classification system in the US uses which regulatory framework?

    Answer: GHS/OSHA Hazard Communication Standard

    The GHS (Globally Harmonized System) adopted by OSHA's Hazard Communication Standard classifies reproductive and developmental toxicants into Category 1A, 1B, and 2 based on evidence strength.

  4. Which drug is a known human teratogen classified FDA Category X and causes fetal hydantoin syndrome?

    Answer: Phenytoin

    Phenytoin causes fetal hydantoin syndrome, characterized by craniofacial abnormalities, digit/nail hypoplasia, and cognitive impairment, and is classified FDA Category X (contraindicated in pregnancy).

  5. Which mechanism explains the selective vulnerability of the fetal brain to methylmercury neurotoxicity?

    Answer: Incomplete blood-brain barrier and active neuronal migration in the developing CNS

    The immature blood-brain barrier and ongoing neuronal migration, proliferation, and differentiation during fetal development make the fetal CNS highly vulnerable to methylmercury neurotoxicity.

  6. Which endocrine-disrupting chemical is associated with clear cell adenocarcinoma of the vagina in daughters of women treated during pregnancy?

    Answer: Diethylstilbestrol (DES)

    DES (diethylstilbestrol), a synthetic estrogen prescribed from the 1940s–1970s, caused transplacental carcinogenesis resulting in vaginal clear cell adenocarcinoma in DES daughters.