Grantee Research Project Results

Final Report: Development of a Community-Based Lead Risk and Mitigation Model

EPA Grant Number: CR839376
Title: Development of a Community-Based Lead Risk and Mitigation Model
Investigators: Cuppett, Jonathan
Institution: Water Research Foundation , Cornwell Research Group , University of Florida
EPA Project Officer: Hahn, Intaek
Project Period: May 1, 2018 through April 30, 2021 (Extended to April 30, 2024)
Project Amount: $1,981,000
RFA: National Priorities: Transdisciplinary Research into Detecting and Controlling Lead in Drinking Water (2017) RFA Text | Recipients Lists
Research Category: Endocrine Disruptors , Drinking Water , Water

Objective:

The project team completed the tasks related to the development of the risk based computational model during this project. Work was completed to finalize the model for use and finalize the model and its on-line access.

Other model development tasks were completed during this project, as described below. The goals of the project did not change from those described in our original research plan.

Summary/Accomplishments (Outputs/Outcomes):

Other model development tasks were completed during this project, as described below. The goals of the project did not change from those described in our original research plan.

Task 1. Quantitative Lead Risk Model (QLRM)

The model development required several sub-modules to be created. Central to the model is the module to convert water lead levels (WLL) to blood lead levels (BLL) and then to IQ and Cardiovascular-Pulmonary (CVP) impacts. The module was developed and a spreadsheet calculation was developed for the conversions. That module is described in Task 1a. Another module is the WLL input. One basic input is the measured WLL generally reported as the 1^st liter or 5^th liter draw as required under the Lead and Copper Rule (LCR) and its revisions and improvements (LCRR/LCRI). One of the goals of the input module was to convert the input WLL to a time weighted exposure. A third module is the mitigation routine that accepts an action and estimates the change in WLL. We developed relationships to predict lead reduction after a lead line replacement and after a change in action level goal. Those were programmed into the model.

Task 1a. Development of Health Outcomes Module

Dr. Crawford Brown led the work on the health outcomes portion of the model. The effort in this project was in further developing and enhancing the structure of the model, including inputs required, outputs generated and sensitivity analysis capability. The structure was enhanced and focused on IQ impacts and cardio vascular pulmonary effects. A major effort was made to adjust the outputs of the model to be more user friendly.

Task 1b. Development of Engineering Side of the Model (Mitigation impacts on WLL)

The overall objective of this task was to improve prediction of WLL through the model in the mitigation step. It is especially useful in the mitigation module for estimating changes in lead levels based on mitigation strategies employed. The approach was to collect and utilize existing data, supplemented with additional data collection to build relationships among the variables that when coupled with probabilistic analysis allows for better WLL prediction. The following subtasks were designed to help develop these inputs.

1. We compiled a database through utility volunteers to obtain composite exposure samples that can relate LCR sample methods to exposure. We were successful in developing a predictive relationship between the first or fifth liter and the consumption/exposure sample. This work was presented at the 2023 AWWA ACE and the slides are appended to this report.

2. We completed work on lab lead solubility related to theoretical solubility curves to better assist in estimating how a treatment change could impact lead levels. A paper with these findings has been completed and submitted for publication consideration.

3. We have developed predictive relationships for estimating the lead level after a lead service line replacement. We have close to 1000 data points in the prediction. We have added additional data obtained from other utilities into the predictive model. We also completed development of predicting a community’s lead levels after a decision is made to lower the action level goal.

4. We completed experiments with lead pipes to better understand chemistry changes that can cause lead release.

Task 1 b 1. Forensic Lead Isotope Analysis

We acquired IRB approval in January 2021 and also for the Pueblo, CO DPH. We obtained blood samples and environmental samples of lead from two children in Colorado and from an adult with elevated blood lead levels from Rhode Island and demonstrated a correlation between the lead isotopes in blood samples and the lead dust in the home. Isotope ratios were determined in both concentrated acid digested samples and gastric juice extracted samples (ref. EPA Method 1340). These results indicated that the lead in blood originated from primarily paint dust.

Task 1 b 2. Laboratory studies on lead isotopes

The UF team, led by Dr. George Kamenov, conducted lead isotope analyses on water, drinking water pipes, and pipe scales samples. A presentation on the technique and results was given during the AWWA ACE 2022. Part of this work was assessing lead release in galvanized pipes so the benefits of replacing galvanized pipes can be better quantified. A paper was also published on this topic.

Task 1 b 3. Laboratory work to verify the utility of solubility models for lead scale dissolution

UF, led by Dr. Jean Claude Bonzongo, conducted laboratory studies on the prediction of the dissolution of lead from scale materials with known solid phase mineral composition as a function of water chemistry. Laboratory studies to determine the dissolution of lead caused by changes in key water chemistry parameters (e.g., pH, DIC, phosphate, water hardness, and DOC) in static conditions were completed. This research effort included a comparison of experimental and geochemical modeling approaches. A manuscript for publication of these results was prepared and submitted for publication. A second set of laboratory studies was conducted on the dissolution of Pb from intact drinking water pipes’ scales, this time using pipe loops conditioned with water from Gainesville, Florida. The student’s PhD dissertation was also completed.

Task 1 b 4. Home level research on lead release

CRG had planned research in an abandoned home in Flint, MI to better understand which parameters influence the release of lead in a home, thereby contributing to the WLL. Because of Covid mandated restrictions, CRG was unable to secure a site for this work. We pivoted on this task and gathered lead release data from a simulated home piping system constructed at our facility. Harvested lead lines, plumbing fixtures with lead and copper pipes with lead solder were used to create the model built in CRG’s test facility. Sampling plans and protocols were established to isolate the variables in the model. The model was run during this project with a focus on establishing the relationship between sequential sampling (specifically first and fifth liter) and the actual measured lead in the pipes. This work was presented at the AWWA ACE Convention June 2023.

Task 1 b 5. Assessment of bioavailability of particulate metals in scales

To assess the bioavailability of particulate metals in corrosion scales and to determine the potential human exposure risks associated with the ingestion of corrosion particles, we conducted laboratory studies in which corrosion scales retrieved from excavated drinking water pipes pre-characterized by XRD (mineral identification) and ICP-MS (total metal concentrations) were used

T.1.C Web Application Development

Concurrent with the development of the Lead Risk and Mitigation Models, the Development Team created a web-based application to provide a communication framework for the model created by the Research Team. The “Quantitative Lead Risk Model" web application consists of the following functionality:

Home Screen

Input Module

Lead Exposure

Lead Exposure Impact on IQ

Mitigation Strategies

Benefits

Economic Costs and Benefits

The series of pages with questions to be answered leads the user to the final section of the application which shows the users the projected project costs, as well as the anticipated benefits. After viewing the benefits, the users have the ability to revise the mitigation strategy, change the data inputs or exit the study. The Model Development Team participated in a series of internal workshops to improve and test the model.

Task 2. Lead Reduction Strategies

Using various datasets, we determined the impact of various mitigation strategies on reducing the lead levels in consumers’ taps.

Task 3. Education and Outreach

We focused our communication efforts on various segments of the water community, through WRF and AWWA outreach opportunities. We participated in a number of regional and national AWWA conferences where we have presented the findings of the work described here, as well as a general discussion of the model.

Conclusions:

The development of the Lead Risk and Mitigation Model was completed through this project. The model requires a number of modules, and central to the model is the module to convert water lead levels (WLL) to blood lead levels (BLL) and then to IQ and CVP impacts.

Similarly, work was completed on the engineering side of the model. That is, analysis of datasets to determine factors which affect the WLL in water consumed. Model predictions were developed for converting lead data collected in the LCR or future LCRR into exposure values for input into the BLL model. Predictive models were also developed for mitigation strategies involving replacing lead service lines or changing a community’s action level goal.

The research team developed a database of lead isotopes and isotope ratios from various waters, plumbing materials, and pipe scales from a number of water systems. This database will help inform the users regarding lead sources in drinking water.

Concurrently, the research team developed the web-based application that allows general utilization of the model. The user interface is primarily used for visual design and layout and serves as a way for the user to interact with the calculations programmed into the microservices and related database.

Journal Articles:

No journal articles submitted with this report: View all 6 publications for this project

Progress and Final Reports:

Original Abstract

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.