Lead is a potent neurotoxin that impairs children’s intellectual development and alters their behavior and ability to concentrate. The impacts of lead exposure during childhood are permanent. There is a strong scientific consensus that any amount of lead exposure during childhood is harmful.
An estimated 500,000 American children have lead exposures in excess of 5 micrograms lead per deciliter of blood, or μg/dL, the Centers for Disease Control and Prevention's current threshold for elevated childhood blood lead levels, at which a public health intervention is recommended. And federal health officials are considering whether to classify even lower levels of lead as potentially requiring medical attention.
Lead-based paint has historically been the main source of exposure for American children. Over the past several decades, federal and state governments have invested in cleaning up lead hazards, and blood lead levels have declined notably. Yet even the comparatively low levels of lead exposures now measured in American children cause intellectual impairment and behavior problems. Lead contamination of drinking water remains a problem for many communities across the United States, and a contributor to lead exposure for thousands of children.
Why is lead in drinking water?
Lead water pipes were used in hundreds of cities, most commonly in water lines installed before the 1930s. In 2016, the American Water Works Association estimated that 15 to 22 million Americans drink water from a water system with lead-based service lines. Lead pipes are also found inside most homes built before 1930, and lead-based plumbing solder was used to join metal water pipes through 1986. Since lead levels vary from one house to another, it is difficult to estimate how many people have contaminated water in their homes.
Over time lead pipes build up a protective coating, which limits lead leaching into the water. The EPA has set an action level of 15 parts per billion, or ppb, for lead in water, based on the principle that when water utilities properly manage the corrosivity of drinking water, they can keep the protective coating intact and generally keep lead levels below this level. But as found in recently in Flint, Mich., some water utilities fail to proper manage lead risks, jeopardizing public health. Also, any maintenance or replacement of a home’s plumbing or water service lines can disturb the protective coating and increase amounts of lead in water.
Is there a safe level for lead in water?
Lead exposure is primarily a risk during the first six years of life, when children’s brains are developing rapidly and their blood-brain barrier isn’t yet formed. Babies fed formula mixed with tap water are at highest risk from lead in drinking water.
The EPA’s water guideline of 15 ppb for lead was set to monitor a water system’s efforts to manage water corrosivity and maintain protective coatings on pipes. It is not based on a safe exposure level for children. Further, under current federal rules, it is perfectly legal for lead levels to exceed 15 ppb in up to 10 percent of households tested.
The EPA is still at the drawing board, working to determine how much lead is “safe” in drinking water. Its preliminary calculations suggest that the risks are most intense for infants fed baby formula mixed with tap water. The Environmental Defense Fund analyzed the preliminary EPA calculations and reported that when infants live in a house built before 1950, lead levels above 3.8 ppb put a formula-fed baby at a 1 percent risk of exceeding the blood lead action level. But so long as the health-protective revisions to the Lead and Copper rule are not finalized by the EPA, children will remain at risk from too much lead in drinking water.
In 2009, the California Office of Health Hazard Assessment set a public health goal for lead in drinking water at 0.2 ppb to protect against harm to the brain and nervous system in children. This health guideline was based on studies of children showing that an increase of 1 ug/dL of lead in blood was correlated with a decrease of one IQ point. To set a health goal value based on the loss of one IQ point, the agency added an uncertainty factor of three and assumed that water accounted for just 20 percent of total lead exposures that a child might face.
EWG urges the federal government to set a protective legal limit for lead in drinking water, as it does for other water contaminants. The EPA should require more aggressive action to monitor houses for lead contamination, and compel water companies to speed up their plans to replace water service lines. Since childhood lead exposures below the CDC action level are also associated with lower IQ and behavioral problems, EWG agrees with the EPA that the ideal concentration of lead in drinking water is zero.
The Lead and Copper Rule
The Flint catastrophe prompted a renewed focus on the role of contaminated drinking water in America’s lead crisis. The EPA has been reassessing its Lead and Copper Rule, but the public does not know when new, health-protective standards for lead might be established.
The existing rule requires drinking water providers to test a portion of homes for lead every year. But there are a lot of loopholes that allow water utilities to collect samples in ways that underreport lead risks. These include selecting homes without lead problems for sampling, flushing pipes before collecting the water sample, and running water at low velocity while filling the sample jar.
Due to the gaps in the EPA-mandated testing, it is difficult to draw conclusions about the true number of people at risk from lead in drinking water. The data collected reflect the qualities of the houses selected for sampling. Water companies are supposed to instruct homeowners to collect water samples first thing in the morning, based on the idea that this water holds the most lead. But in some cases the highest lead levels will be found in the water that sits in water service lines under the street overnight, which is only detected in samples collected after water runs for several minutes. But since this varies from one house to the next, it makes it more challenging to know whether single point samples under- or over-represent lead risks.
The only permanent solution to the crisis of lead in tap water is to replace lead-based water pipes. The federal government must require faster replacement of lead-based water service lines, which should also include replacing the portion of pipes that run from the street to the house entrance, which are normally considered property of the homeowner and therefore the owner’s financial responsibility.
What can water utility customers do?
The only way to know if the water in your house contains lead is by testing it. Lead kits are readily available, and may even be provided by the local water utility, as well as by government agencies and nonprofit public interest organizations. Testing for lead is particularly important if:
- You have lead-based water lines leading to your house;
- Your local water company has detected lead in water your neighborhood; or
- You drink water from a private well and your local public health department detects lead in well water in your area.
The amount of lead in water can be reduced by using a home water filter, flushing cold water pipes each morning and using only cold water for cooking. But these are just temporary solutions. The only permanent fix to chronic lead contamination in your drinking water is replacing lead-based water pipes in the entire water system.
David A. Cornwell et al., National Survey of Lead Service Line Occurrence. Journal of the American Water Works Association, 2016, 108(4): E182-E191. Available at www.awwa.org/publications/journal-awwa/abstract/articleid/57880483.aspx
California Office of Environmental Health Hazard Assessment, Public Health Goal for Lead in Drinking Water. 2009. Available at oehha.ca.gov/media/downloads/water/chemicals/phg/leadfinalphg042409_0.pdf
CDC, Sources of Lead: Water. 2016. Available at www.cdc.gov/nceh/lead/tips/water.htm
EPA, Lead and Copper Rule. 1991. Available at www.epa.gov/dwreginfo/lead-and-copper-rule
EPA, Proposed Modeling Approaches for a Health-Based Benchmark for Lead in Drinking Water. 2017. Available at www.epa.gov/sites/production/files/2017-01/documents/report_proposed_modeling_approaches_for_a_health_based_benchmark_for_lead_in_drinking_water_final_0.pdf
O. Milman and J. Glenza, At Least 33 US Cities Used Water Testing 'Cheats' Over Lead Concerns. Guardian News, 2016. Available at www.theguardian.com/environment/2016/jun/02/lead-water-testing-cheats-chicago-boston-philadelphia
T. Neltner, EDF’s Assessment of a Health-Based Benchmark for Lead in Drinking Water. Environmental Defense Fund, 2017. Available at blogs.edf.org/health/2017/02/28/health-based-action-level-for-lead-in-drinking-water/