Exposure and Risk
In the United States, about 3% of babies are born with structural birth defects. Most birth defects are thought to be caused by a complex mix of genetic, behavioral, and environmental factors, although, for many birth defects, exactly how these factors work together is unclear.
It is not clear how many birth defects are related to environmental exposures, such as chemicals, drugs, and ionizing radiation. Some endocrine-disrupting 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. But, we need more data to make these connections clearer.
Living near a hazardous waste site has been identified as a possible risk factor for birth defects including: spina bifida, cleft lip or palate, gastroschisis, hypospadias, chromosomal congenital anomalies such as Down syndrome, 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 which affect the brain and spinal cord, the urinary tract, and the heart.
We know the cause of some birth defects but for most we dont. We do know that some women have a higher chance of having a child with a birth defect:
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