Healthy homes need healthy water: toward a lead in water risk assessment tool

Children are exposed to lead in homes through paint, dust, soil, and toys. What is often not considered, however, is the potential exposure to lead from drinking water in their homes and schools. The Center for Disease Control (CDC) has determined there is no safe level of lead exposure because at low levels, lead can have irreversible health impacts on children. Currently, despite drinking water being a known potential source of lead, it is not considered in most assessments of children's risk of lead exposure. Since the best way to protect children from lead exposure is to prevent it from happening in the first place (i.e., primary prevention), it is critical we understand and identify what sources contribute to lead in water so that we can effectively remove those sources and prevent children being exposed to lead from water.

Using data from the Flint, Michigan drinking water crisis, I found that the material drinking water service lines are made from influenced the risk of children having lead in their blood above a certain level. The risk of children having lead in their blood above 2 μg/dL doubled in all homes during the Flint water crisis, regardless of service line material. Children living in homes with lead service lines and galvanized pipes, however, were more likely to higher blood lead levels compared to children living in homes with full copper service lines (i.e. no known lead service line). These findings indicate that while lead service lines and galvanized pipes increased children's risk, even homes without known lead lines experienced water lead contamination which begs the question – where did this lead come from?

Lead in water is known to come from the service lines as well as premise plumbing, such as faucets and solder, found inside of homes but it is difficult to identify which of these sources is dominant. I identified the likely lead sources in homes with different service lines by looking at how metals known to be related to plumbing materials varied with different service line materials. Based on my findings that homes without any known source of lead still had lead in their water as well as an increased risk of lead in children's blood, I suggest that important lead sources will remain even after lead service lines are removed as currently planned by the Biden administration. Put more simply, I argue that ignoring homes with full copper lines misses significant risk of children being exposed to lead through drinking water.

Lead in drinking water is also known to be missed by the way we assess whether lead is present in drinking water at high enough concentrations for EPA to take corrective measures. The current approach to assess whether a water system complies with EPA's Lead and Copper Rule (LCR) allows for up to 10% of homes tested in a community to have elevated lead levels without any additional action or public notification needed. I found that including a few additional homes (i.e., only allowing up to 5% of homes to have elevated lead levels) had a three-fold increase in the number of water systems that would require corrective action.

Overall, the findings in my thesis have changed the way I think of and evaluate for risk of exposure from lead in drinking water. As I move forward, I will use these results to help create a water lead risk score (WLRS) so that we may target those most in danger of being exposed to contaminated water before they ever drink it - because healthy children need healthy water.