Final answer:
The harm caused by teratogens is dependent on the timing of the exposure during fetal development, with effects varying from physical abnormalities to lasting cognitive and behavioral issues.
Step-by-step explanation:
The harm done by teratogens depends in part on the age at the time of exposure. Teratogens are environmental agents that can cause damage to the developing embryo or fetus. A few key factors contribute to the impact of teratogens, including the duration of teratogen exposure, the specific time during development when exposure occurs, the level of transfer from maternal to fetal circulation, the potency of the teratogen, and the susceptibility of the fetus.
The effects of teratogens are not always apparent at birth and can range from physical abnormalities to cognitive and behavioral issues that may manifest later in life. For instance, alcohol, a well-known teratogen, can cause fetal alcohol spectrum disorders, which exhibit a range of physical, cognitive, and behavioral problems that endure into adulthood.