Which statement reflects a limitation of tox studies in preclinical trials?

• A. Fetal events in humans always match animal findings
• B. Toxicology studies replace human trials
• C. They predict all adverse events in humans
• D. Fetal events in humans may occur that did not occur in animals

Answer: (D)

Preclinical toxicology aims to flag safety risks before humans are exposed, but it cannot fully predict fetal risk in people. Differences in development, placental transfer, metabolism, and dosing between animals and humans mean some fetal effects may occur in humans that were not seen in animal studies. This is why fetal events in humans may arise even when animal studies did not show them.

That’s why statements claiming that fetal outcomes always match animal findings, that tox studies replace human trials, or that they predict all adverse events in humans aren’t accurate. Animal data are essential but imperfect, and human trials with careful safety monitoring remain necessary to fully understand fetal risks.