Researchers from the University of Pennsylvania’s NIEHS-funded Center of Excellence in Environmental Toxicology developed an index to predict risk of lead exposure. The index is unique in that it considers socioeconomic and demographic factors in addition to environmental lead levels. It is intended to support decision-making when identifying geographic areas most in need of remediation. A goal is to assist health equity, which means everyone has a just opportunity to achieve optimal health. In a recent paper, researchers describe how they developed the Lead Index across Philadelphia.

Citizen Science Supports Soil Sampling

To develop a picture of soil lead levels throughout Philadelphia, researchers gathered data by collecting soil samples, using existing data from the Environmental Protection Agency, conducting student soil collections through Academically Based Community Service classes, and by receiving soil samples from community members at “soil workshops.”

Through the Academically Based Community Services classes, undergraduate students worked with middle and high school teachers to get local students involved in activities to understand environmental research and apply what they learned to their own homes.

“Students and residents who are engaged through citizen science develop a deeper understanding of the hazards of lead in soil in their yards,” said Center of Excellence in Environmental Toxicology researcher Richard Pepino, M.S.S., M.S., who developed and led Academically Based Community Service classes on soil lead. “When the effects feel personal, people are more determined to reduce their risk of harmful environmental exposures.”

Researchers also held soil workshops in partnership with local organizations including the Overbrook Environmental Education Center, Public Citizens for Children and Youth, and government agencies including the Environmental Protection Agency and the Agency for Toxic Substances and Disease Registry.

The workshops provided an opportunity for residents to drop off soil samples and for researchers to engage with community members by providing information on lead exposure and associated health risks, particularly to children. The workshops were advertised through community newspapers, newsletters, and social media. Instructions on soil collection were provided by partnering organizations on-site. Full instructions and videos on soil sampling were posted on the Community Engagement Core’s website.

In addition to determining the concentration of lead in the soil, the researchers and students recorded the specific geographic coordinates of each sample site, which allowed the samples to be mapped.

“Measuring lead content in soil is one of the best approaches to map lead contamination across different geographic areas,” said Reto Gieré, Ph.D., professor of Earth and Environmental Science, who led the sampling and analysis efforts. “Lead remains in soil over time from industrial sources, such as smelters; materials, such as paint from old buildings; and remnants of lead from gasoline. Contact with soil is one of the primary ways that children are exposed to lead, in addition to direct exposure to lead-based paints in older homes.”

Developing the Index

In addition to soil content, the Lead Index incorporated factors the researchers determined were strongly correlated with exposure to lead, which included:

• Median income
• Number of demolitions
• Percent of children in poverty
• Percent of children with elevated blood-lead levels
• Percent of minority population
• Percent of owner-occupied properties
• Percent of properties built before 1980

Researchers gathered data for each factor from existing datasets and calculated mean values by ZIP code. Soil lead levels were also grouped by ZIP code by taking the median values of all samples in that area. The researchers then assigned weights to the factors by ranking the strength of their association with lead exposure. The Lead Index was calculated for each ZIP code in the city.

“One of our goals is to address environmental justice issues in our region. It is important to document how multiple factors combine to impact vulnerable communities,” stated Marilyn Howarth, M.D., principal investigator of the Community Engagement Core. “Our Lead Index helps to identify those with the greatest socioeconomic inequities who are also at highest risk of exposure to lead. Through ZIP code mapping, we are able to identify areas of vulnerability where remediation may be needed most, and areas that should be protected from additional lead exposure from all sources.”

Using the Lead Index to Make Progress Towards Health Equity

The researchers plan to use the data to target their educational outreach efforts and community partnerships to achieve environmental health equity. Researchers also plan to analyze more samples to strengthen the Lead Index, especially for areas not well represented by the original sampling.

“Our work has provided new strategies for local public health officials. Our index will identify neighborhoods that warrant additional blood screening to promote earlier detection of children with elevated blood-lead levels,” said Pepino.

With Lead Index measures for all areas in the city, the researchers hope to inform policies that would reduce lead exposure for vulnerable communities. This research findings have been provided to the Pennsylvania Department of Environmental Protection, as evidence for addressing the soil lead standard in the state. The Lead Index may also be used by regulators and legislators to prioritize remediation funding and lead service line replacements.