ABSTRACT
This chapter discusses the potential of drugs and radiation to produce birth defects in humans will be explored. Wilson has estimated that of all human malformations, less than 1% are due to radiations and 4% to 6% are due to drugs and environmental chemicals. Drugs that fulfill the criteria for a human teratogen may produce their effect directly, indirectly, or through a toxic intermediate. Whether an agent produces a teratogenic effect is dependent on the timing of the insult. The teratologic literature is usually reported in post-conception weeks. Drugs that fulfill the criteria for a human teratogen may produce their effect directly, indirectly, or through a toxic intermediate. Direct-acting teratogens cause damage in their native form and require only access to the conceptus to do harm. Special mention should be made of radioiodine during pregnancy. Iodine-131, if given in millicurie doses, can damage or ablate the developing fetal thyroid resulting in either congenital hypothyroidism or hypothyroidism of late onset.
