Researchers Lehigh University and Bentley University Health Economics have published the first study to confirm a causal relationship between lead in water and adverse fetal health outcomes. Their study exploits an exogenous, or extrinsic, change in the pH level of water that leads to leakage into the drinking water of a plant’s service area to identify the causal effect of prenatal lead exposure on fetal health, but not of another. According to the American Academy of Pediatrics, there is no known safe limit for lead exposure for children. Lead accumulates over time in the human body through repeated exposure and gets deposited in the bones along with calcium. Exposure in utero is of particular concern because lead can be mobilized into the mother’s bones during pregnancy and released as a calcium substitute to aid in fetal bone formation, and lead into the mother’s blood. Can also cross the placenta. fetus to lead poisoning.