the science informing our work
Lead in water and lead in blood
In contrast to lead-tainted paint, dust, and soil, lead-bearing plumbing is present in almost every US building. Water flowing through such plumbing is ingested regularly by people of all ages, directly or through food.
Studies on lead in water and lead in blood have been published in peer-review journals for over half a century. The papers below were published in the last 15 years, after the historic Washington, DC lead-in-water crisis of 2001-2004. They provide scientific depth, complexity, and nuance necessary for understanding lead at the tap, enacting public health protective policies, and developing reliable public messaging about the problem. Several of the papers also show that oft-repeated claims about lead in water being a secondary or insignificant source of exposure are simplistic, misleading, and inaccurate.
Lead from water can be the primary or even sole source of exposure in both the general population and vulnerable subgroups, such as fetuses and formula-fed infants.
As we indicate in several of our position statements, this reality is routinely masked by:
Water sampling methods that are inappropriate for capturing lead release from plumbing;
Blood lead screening programs that are not designed to capture human exposures to lead from water;
Federally mandated public education that lacks complete and accurate information;
Environmental risk assessments in children’s homes that omit, or include improper, lead-in-water testing; and
Commonly cited studies examining the relation between lead in the environment and in children’s blood that employ erroneous assumptions about lead corrosion including, for example, that lead-in-water levels at any single tap remain steady over time.
The papers we highlight form the backbone of our calls for scientifically sound, just, and equitable solutions to the problem of lead in water.
Tully, J., M. Schock, S. Shilling, V. Bosscher, D. Lytle, S. Harmon, and C. Bennett-Stamper. 2024. An evaluation of properly operated NSF/ANSI-53 Pb certified drinking water filters in Benton Harbor, MI. Journal of Water and Health doi: 10.2166/wh.2024.231.
Abstract
Communities across the United States and particularly in the Midwest continue to grapple with the complications associated with aging infrastructure. This includes the presence of lead (Pb)-bearing plumbing components such as lead service lines, downstream galvanized iron pipes, and Pb/tin solder. The community of Benton Harbor, MI, experienced six Pb action level exceedances between 2018 and 2021, leading to increasing community concern and a request from the state of Michigan for the US Environmental Protection Agency involvement. Between 9 November and 17 December 2021, US EPA Region 5 and Office of Research and Development, along with the state of Michigan, conducted a water filter efficacy and Pb-nanoparticulate (,100 nm) study to evaluate the performance of NSF/ANSI-53 Pb-certified drinking water filters and the presence of nanoparticulate. In this study, a total of 199 properly installed and operated drinking water filters (combination of faucet mounted and pitcher) were tested in their residential locations. One hundred percent of the water filters were found to perform to the standard to which they were certified, with filtered drinking water Pb concentrations below 5 ppb (maximum observed was 2.5 ppb). In addition, Pb particulate was identified; however, discrete Pb-containing nanoparticles were not widely found or identified.
Note: This paper is available here.
Betanzo, E. 2024. Is my faucet lead free? Understanding new “lead-free” requirements for faucets and household plumbing [blog post]. Safe Water Engineering (Jan 10).
Description
This blog post summarizes new requirements for low lead “lead-free” plumbing devices, outlines what to look for when shopping for new plumbing materials, and identifies older materials that might put you at increased risk of lead exposure.
Note: This blog post is available here.
Triantafyllidou, S., J. Burkhardt, J. Tully, K. Cahalan, M. DeSantis, D. Lytle, and M. Schock. 2021. Variability and sampling of lead (Pb) in drinking water: Assessing potential human exposure depends on the sampling protocol. Environment International 146:106259.
Abstract
Lead (Pb) in drinking water has re-emerged as a modern public health threat which can vary widely in space and in time (i.e., between homes, within homes and even at the same tap over time). Spatial and temporal water Pb variability in buildings is the combined result of water chemistry, hydraulics, Pb plumbing materials and water use patterns. This makes it challenging to obtain meaningful water Pb data with which to estimate potential exposure to residents. The objectives of this review paper are to describe the root causes of intrinsic Pb variability in drinking water, which in turn impacts the numerous existing water sampling protocols for Pb. Such knowledge can assist the public health community, the drinking water industry, and other interested groups to interpret/compare existing drinking water Pb data, develop appropriate sampling protocols to answer specific questions relating to Pb in water, and understand potential exposure to Pb-contaminated water. Overall, review of the literature indicated that drinking water sampling for Pb assessment can serve many purposes. Regulatory compliance sampling protocols are useful in assessing community-wide compliance with a water Pb regulatory standard by typically employing practical single samples. More complex multi-sample protocols are useful for comprehensive Pb plumbing source determination (e.g., Pb service line, Pb brass faucet, Pb solder joint) or Pb form identification (i.e., particulate Pb release) in buildings. Exposure assessment sampling can employ cumulative water samples that directly capture an approximate average water Pb concentration over a prolonged period of normal household water use. Exposure assessment may conceivably also employ frequent random single samples, but this approach warrants further investigation. Each protocol has a specific use answering one or more questions relevant to Pb in water. In order to establish statistical correlations to blood Pb measurements or to predict blood Pb levels from existing datasets, the suitability of available drinking water Pb datasets in representing water Pb exposure needs to be understood and the uncertainties need to be characterized.
Note: This paper is available here.
Stanek, L. W., J. Xue, C. R. Lay, E. C. Helm, M. Schock, D. A. Lytle, T. F. Speth, and V. G. Zartarian. 2020. Modeled Impacts of Drinking Water Pb Reduction Scenarios on Children’s Exposures and Blood Lead Levels. Environmental Science & technology 54(15):9474-9482.
Abstract
In recent years, environmental lead (Pb) exposure through drinking water has resulted in community public health concerns. To understand potential impacts on blood Pb levels (BLLs) from drinking water Pb reduction actions (i.e., combinations of lead service lines [LSL] and corrosion control treatment [CCT] scenarios), EPA’s Stochastic Human Exposure and Dose Simulation (SHEDS)-Multimedia/Integrated Exposure Uptake and Biokinetic (IEUBK) model was applied for U.S. children aged 0 to <6 years. The results utilizing a large drinking water sequential sampling data set from 15 cities to estimate model input concentration distributions demonstrated lowest predicted BLLs for the “no LSLs” with “combined CCT” scenario and highest predicted BLLs for the “yes LSLs” and “no CCT” scenario. Modeled contribution to BLLs from ingestion of residential drinking water ranged from ∼10 to 80%, with the highest estimated for formula-fed infants (age 0 to <1 year). Further analysis using a “bounding” data set spanning a range of realistic water Pb concentrations and variabilities showed BLL predictions consistent with the sequential sampling-derived inputs. Our study illustrates (1) effectiveness of LSL replacement coupled with CCT for reducing Pb in drinking water and children’s BLLs, and (2) in some age groups, under realistic local and residential water use conditions, drinking water can be the dominant exposure pathway.
Note: This paper is available here.
Pieper, K. J., V. E. Nystrom, J. Parks, K. Jennings, H. Faircloth, J. B. Morgan, J. Bruckner, and M. A. Edwards. 2018. Elevated Lead in Water of Private Wells Poses Health Risks: Case Study in Macon County, North Carolina. Environmental Science & Technology 52:4350−4357.
Abstract
Recent research has indicated that lead in water of private wells is in the range of that which caused problems in Flint, Michigan. However, there is limited understanding of the mechanisms for water lead release in these systems. We evaluated water lead at the homes of two children with elevated blood lead in Macon County (North Carolina), which did not have identifiable lead paint or lead dust hazards, and examined water lead release patterns among 15 private wells in the county. Water lead release patterns differed among the 15 private wells. Problems with lead release were associated with (1) dissolution of lead from plumbing during periods of stagnation; (2) scouring of leaded scales and sediments during initial water use; and (3) mobilization of leaded scales during continued water use. Accurate quantification of water lead was highly dependent on sample collection methods, as flushing dramatically reduced detection of lead hazards. The incidence of high water lead in private wells may be present in other counties of North Carolina and elsewhere in the United States. The underestimation of water lead in wells may be masking cases of elevated blood lead levels attributed to this source and hindering opportunities to mitigate this exposure.
Note: This paper is behind a paywall. If you would like a copy, please let us know.
Hanna-ATTisha, M., J. LaChance, R. C. Sadler, and A. C. Schnepp. 2016. Elevated Blood Lead Levels in Children Associated with the Flint Drinking Water Crisis: A Spatial Analysis of Risk and Public Health Response. American Journal of Public Health 106:283-290.
Abstract
Objectives. We analyzed differences in pediatric elevated blood lead level incidence before and after Flint, Michigan, introduced a more corrosive water source into an aging water system without adequate corrosion control.
Methods. We reviewed blood lead levels for children younger than 5 years before (2013) and after (2015) water source change in Greater Flint, Michigan. We assessed the percentage of elevated blood lead levels in both time periods, and identified geographical locations through spatial analysis.
Results. Incidence of elevated blood lead levels increased from 2.4% to 4.9% (P < .05) after water source change, and neighborhoods with the highest water lead levels experienced a 6.6% increase. No significant change was seen outside the city. Geospatial analysis identified disadvantaged neighborhoods as having the greatest elevated blood lead level increases and informed response prioritization during the now-declared public health emergency.
Conclusions. The percentage of children with elevated blood lead levels increased after water source change, particularly in socioeconomically disadvantaged neighborhoods. Water is a growing source of childhood lead exposure because of aging infrastructure.
Note: This paper is available here.
Masters et al. 2017. Inherent Variability in Lead and Copper Collected During Standardized Sampling [conference presentation].
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Masters, S., J. Parks, A. Atassi, and M. Edwards. 2016. Inherent Variability in Lead and Copper Collected During Standardized Sampling. Environmental Monitoring and Assessment 188(3):177.
Abstract
Variability in the concentration of lead and copper sampled at consumers’ taps poses challenges to assessing consumer health threats and the effectiveness of corrosion control. To examine the minimum variability that is practically achievable, standardized rigs with three lead and copper containing plumbing materials (leaded brass, copper tube with lead solder, and a lead copper connection) were deployed at five utilities and sampled with regimented protocols. Variability represented by relative standard deviation (RSD) in lead release was high in all cases. The brass had the lowest variability in lead release (RSD = 31 %) followed by copper-solder (RSD = 49 %) and lead-copper (RSD = 80 %). This high inherent variability is due to semi-random detachment of particulate lead to water, and represents a modern reality of water lead problems that should be explicitly acknowledged and considered in all aspects of exposure, public education, and monitoring.
Note 1: This paper is behind a paywall. If you would like a copy, please let us know.
Note 2: A 2017 conference presentation of this paper includes a noteworthy slide (PDF page 20), which shows that in cases of extreme lead-in-water variability, assessing average lead release from a single tap to within 20% of the true mean would require collecting over 1,287 water samples.
Triantafyllidou, S., D. Gallagher, and M. Edwards. 2014. Assessing risk with increasingly stringent public health goals: the case of water lead and blood lead in children. Journal of water and health 12(1):57-68.
Abstract
Previous predictions of children's blood lead levels (BLLs) through biokinetic models conclude that lead in tap water is not a primary health risk for a typical child under scenarios representative of chronic exposure, when applying a 10 μg/dL BLL of concern. Use of the US Environmental Protection Agency Integrated Exposure Uptake Biokinetic (IEUBK) model and of the International Commission on Radiological Protection (ICRP) biokinetic model to simulate children's exposure to water lead at home and at school was re-examined by expanding the scope of previous modeling efforts to consider new public health goals and improved methodology. Specifically, explicit consideration of the more sensitive population groups (e.g., young children and, particularly, formula-fed infants), the variability in BLLs amongst exposed individuals within those groups (e.g., more sensitive children at the upper tail of the BLL distribution), more conservative BLL reference values (e.g., 5 and 2 μg/dL versus 10 μg/dL) and concerns of acute exposure revealed situations where relatively low water lead levels were predicted to pose a human health concern.
Note: This paper is available here.
Edwards, M. 2014. Fetal Death and Reduced Birth Rates Associated with Exposure to Lead-Contaminated Drinking Water. Environmental Science & Technology 48:739-746.
Abstract
This ecologic study notes that fetal death rates (FDR) during the Washington DC drinking water “lead crisis” (2000–2004) peaked in 2001 when water lead levels (WLLs) were highest, and were minimized in 2004 after public health interventions were implemented to protect pregnant women. Changes in the DC FDR vs neighboring Baltimore City were correlated to DC WLL (R2 = 0.72). Birth rates in DC also increased versus Baltimore City and versus the United States in 2004–2006, when consumers were protected from high WLLs. The increased births in DC neighborhoods comparing 2004 versus 2001 was correlated to the incidence of lead pipes (R2 = 0.60). DC birth rates from 1999 to 2007 correlated with proxies for maternal blood lead including the geometric mean blood lead in DC children (R2 = 0.68) and the incidence of lead poisoning in children under age 1.3 years (R2 = 0.64). After public health protections were removed in 2006, DC FDR spiked in 2007–2009 versus 2004–2006 (p < 0.05), in a manner consistent with high WLL health risks to consumers arising from partial lead service line replacements, and DC FDR dropped to historically low levels in 2010–2011 after consumers were protected and the PSLR program was terminated. Re-evaluation of a historic construction-related miscarriage cluster in the USA Today Building (1987–1988), demonstrates that high WLLs from disturbed plumbing were a possible cause. Overall results are consistent with prior research linking increased lead exposure to higher incidence of miscarriages and fetal death, even at blood lead elevations (≈5 μg/dL) once considered relatively low.
Note: This paper is available here.
Del Toral, M. A., A. Porter, and M. R. Schock. 2013. Detection and evaluation of elevated lead release from service lines: a field study. Environmental Science & Technology 47(16):9300-9307.
Abstract
Comparative stagnation sampling conducted in 32 homes in Chicago, Illinois with lead service lines demonstrated that the existing regulatory sampling protocol under the U.S. Lead and Copper Rule systematically misses the high lead levels and potential human exposure. Lead levels measured with sequential sampling were highest within the lead service lines, with maximum values more than four times higher than Chicago's regulatory compliance results using a first-draw sampling protocol. There was significant variability in lead values from different points within individual lead service lines and among different lead service line sites across the city. Although other factors could also influence lead levels, the highest lead results most often were associated with sites having known disturbances to the lead service lines. This study underscores the importance and interdependence of sample site selection, sampling protocol, and other factors in assessing lead levels in a public water system.
Note: This paper is available here.
Triantafyllidou, S. and M. Edwards. 2012. Lead (Pb) in Tap Water and in Blood: Implications for Lead Exposure in the united states. Critical Reviews in Environmental Science and Technology 42:1297–1352.
Abstract
Lead is widely recognized as one of the most pervasive environmental health threats in the United States, and there is increased concern over adverse health impacts at levels of exposure once considered safe. Lead contamination of tap water was once a major cause of lead exposure in the United States and, as other sources have been addressed, the relative contribution of lead in water to lead in blood is expected to become increasingly important. Moreover, prior research suggests that lead in water may be more important as a source than is presently believed. The authors describe sources of lead in tap water, chemical forms of the lead, and relevant U.S. regulations/guidelines, while considering their implications for human exposure. Research that examined associations between water lead levels and blood lead levels is critically reviewed, and some of the challenges in making such associations, even if lead in water is the dominant source of lead in blood, are highlighted. Better protecting populations at risk from this and from other lead sources is necessary, if the United States is to achieve its goal of eliminating elevated blood lead levels in children by 2020.
Note: This paper is behind a paywall. If you would like a copy, please let us know.
Brown, M. J., J. Raymond, D. Homa, C. Kennedy, and T. Sinks. 2011. Association Between Children’s Blood Lead Levels, Lead Service Lines, and Water Disinfection, Washington, DC, 1998–2006. Environmental Research 111:67-74.
Abstract
Objective: Evaluate the effect of changes in the water disinfection process, and presence of lead service lines (LSLs), on children's blood lead levels (BLLs) in Washington, DC.
Methods: Three cross-sectional analyses examined the relationship of LSL and changes in water disinfectant with BLLs in children <6 years of age. The study population was derived from the DC Childhood Lead Poisoning Prevention Program blood lead surveillance system of children who were tested and whose blood lead test results were reported to the DC Health Department. The Washington, DC Water and Sewer Authority (WASA) provided information on LSLs. The final study population consisted of 63,854 children with validated addresses.
Results: Controlling for age of housing, LSL was an independent risk factor for BLLs ≥ 10 μg/dL, and ≥ 5 μg/dL even during time periods when water levels met the US Environmental Protection Agency (EPA) action level of 15 parts per billion (ppb). When chloramine alone was used to disinfect water, the risk for BLL in the highest quartile among children in homes with LSL was greater than when either chlorine or chloramine with orthophosphate was used. For children tested after LSLs in their houses were replaced, those with partially replaced LSL were >3 times as likely to have BLLs ≥ 10 μg/dL versus children who never had LSLs.
Conclusions: LSLs were a risk factor for elevated BLLs even when WASA met the EPA water action level. Changes in water disinfection can enhance the effect of LSLs and increase lead exposure. Partially replacing LSLs may not decrease the risk of elevated BLLs associated with LSL exposure.
Note: This paper is available here.
Triantafyllidou, S. and M. Edwards. 2011. Galvanic corrosion after simulated small-scale partial lead service line replacements. Journal of the american water works association 103(9):85-99.
Abstract
Partial lead service line replacement with copper pipe creates a galvanic cell that can accelerate lead corrosion. Bench-scale experiments under stagnant water conditions of high chloride-to-sulfate mass ratio (CSMR) demonstrated that galvanic connections between lead pipe (new or aged) and copper pipe increased lead release into the water by 1.1 to 16 times, compared with a full length of lead pipe alone. The extent of galvanic attack was dependent on drinking water quality. Exposure to water of high CSMR increased lead release in the lead–copper rigs by 3 to 12 times, compared with a less-aggressive low CSMR water. Galvanic current also increased by 1.5 to 2 times when switching from low to high CSMR. The small area of lead pipe adjacent to the copper joint (< 0.5 ft) dissipated 90–95% of the total galvanic current and accumulated a thick (1-in.-wide) layer of lead rust (i.e., a lead-containing scale), which constituted a reservoir for semirandom particulate lead detachment into the water.
Note: This paper is behind a paywall. If you would like a copy, please let us know.
Edwards, M., S. Triantafyllidou, and D. Best. 2009. Elevated Blood Lead in Young Children Due to Lead-Contaminated Drinking Water: Washington, DC, 2001-2004. Environmental Science & Technology 43:1618-1623.
Abstract
Incidence of EBL (blood lead ≥10 μg/dL) for children aged ≤1.3 years in Washington, DC increased more than 4 times comparing 2001−2003 when lead in water was high versus 2000 when lead in water was low. The incidence of EBL was highly correlated (R2 = 0.81) to 90th percentile lead in water lead levels (WLLs) from 2000 to 2007 for children aged ≤1.3 years. The risk of exposure to high water lead levels varied markedly in different neighborhoods of the city. For children aged ≤30 months there were not strong correlations between WLLs and EBL, when analyzed for the city as a whole. However, the incidence of EBL increased 2.4 times in high-risk neighborhoods, increased 1.12 times in moderate-risk neighborhoods, and decreased in low-risk neighborhoods comparing 2003 to 2000. The incidence of EBL for children aged ≤30 months also deviated from national trends in a manner that was highly correlated with 90th percentile lead in water levels from 2000 to 2007 (R2 = 0.83) in the high-risk neighborhoods. These effects are consistent with predictions based on biokinetic models and prior research.
Note: This paper is behind a paywall. If you would like a copy, please let us know.
Triantafyllidou, S., J. Parks, and M. Edwards. 2007. Lead Particles in Potable Water. Journal of the American Water Works Association 99:107-117.
Abstract
The occurrence of particulate lead in drinking water deserves increased scrutiny. This is especially true because models of human exposure to lead, sampling protocols, analytical methods, and environmental assessments are often based on the presumed dominance of soluble lead in drinking water. Recent cases of childhood lead poisoning were tied to solder particles that detached from the plumbing and contaminated the potable water supply. In cases such as these, common sample-handling procedures can “miss” particulate lead present in water samples. In some instances, the actual amount of lead present in drinking water samples may be five times higher than that obtained using approved protocols. The presence of chloride, warmer temperature, and lower pH in the human stomach may render a significant fraction of this “missed” particulate lead as bioavailable when ingested.
Note: This paper is behind a paywall. If you would like a copy, please let us know.