Occupational and Environmental Health: Recognizing and Preventing Disease and Injury - Multiple Choice Questions - Learn & Prevent

Mercury is the correct answer as it is a toxic substance that can cause birth defects when ingested by pregnant women. Thalidomide is incorrect because while it also caused birth defects, it was not found in contaminated food but rather was a prescribed medication for morning sickness. PCBs and DDT are incorrect because while they are also toxic substances, they do not specifically cause severe birth defects in offspring. Overall, mercury was the only substance listed that meets all the criteria provided in the question.