Which type of exposure is used to assess carcinogenicity and teratogenicity?

• A. Acute exposure
• B. Subchronic exposure
• C. Chronic exposure
• D. Intermittent exposure

Answer: (C)

Long-term, or chronic, exposure is needed because cancer and developmental defects are time-dependent outcomes that typically don’t appear after a single short exposure. Carcinogenic effects require sufficient cumulative dose over extended periods for tumors to develop, as cancer involves gradual processes like DNA damage accumulation, mutation fixation, and clonal expansion that unfold over months to years. Teratogenic effects depend on exposure during specific windows of fetal development; providing ongoing exposure across gestation increases the likelihood of hitting those critical periods and revealing malformations or growth issues.

In contrast, an acute exposure might show immediate toxicity but is unlikely to reveal cancer risk or developmental abnormalities that require sustained exposure. Intermittent exposure also risks missing the relevant windows and cumulative dose needed to detect these outcomes.