Which term best describes tobacco, alcohol, radiation, pollution, and certain infectious diseases as agents that can cause birth defects?

• A. Mutagens
• B. Teratogens
• C. Carcinogens
• D. Neurotoxins

Answer: (B)

Teratogens are substances or exposures that disrupt fetal development when a pregnant person is exposed, leading to birth defects or developmental problems. The items listed—tobacco, alcohol, radiation, certain pollutants, and some infectious diseases—are classic examples because exposure during pregnancy can cause structural or functional problems in the developing baby, depending on the timing and dose. The key idea is that teratogens specifically affect the developing fetus and can produce congenital anomalies if the exposure occurs during critical windows of development. In contrast, mutagens cause genetic mutations, often linked to cancer risk rather than birth defects; carcinogens are agents associated with cancer; and neurotoxins primarily affect the nervous system, not necessarily causing birth defects per se.