Birth Defects and the Environment
It is not known what causes approximately 60% of birth defects. The environment remains a source of great public concern, but few environmental exposures have been well-studied. Most birth defects will likely be explained by a complex interaction between genetics and environmental factors. It is not clear how many birth defects are related to environmental exposures, such as chemicals, drugs, and ionizing radiation.
Some chemicals, including polychlorinated biphenyls (PCBs), dioxins, and pesticides, have been linked to nervous system defects and developmental problems such as reduced muscle tone and response. Living near a hazardous waste site has been identified as a possible risk factor for birth defects including: , cleft lip or palate, , , chromosomal congenital anomalies such as , and some heart and blood vessel defects. Exposure to disinfection by-products in drinking water such as trihalomethanes, or THM, may increase the risk of some types of birth defects affecting the brain and spinal cord, the urinary tract, and the heart.
Although some research on how environmental hazards might cause birth defects has been done, much more work is needed to understand the relationship between the environment and birth defects. Doctors and public health scientists know how some birth defects happen and in some cases can make recommendations to help prevent them. But the causes of many other birth defects are unclear. Sharing data about when and where birth defects happen will help scientists understand whether these defects might be related to the environment.