Exposure to lead (Pb) in contaminated soil is a significant health threat for children throughout Peru, a country with a long history of mining. However, Peru does not have the resources to carry out expensive laboratory or field tests to identify hot spots of lead contamination. For this project, the PI Dr. Johny Ponce-Canchihuamán and his team collaborated with U.S. partner Dr. Alexander van Geen to use a new field test kit for Pb in soil developed at Columbia University. They sampled soils in communities representing four different potential contamination types, enabling the researchers to identify areas of high lead risk in communities that are impacted by different lead-contaminating industries, including battery recycling (Lima), ore mining (Cerro de Pasco), smelting (La Oroya), and ore shipping (Callao)

This kit is intended for public use, so the team worked with local high schools to deploy the kits as a hands-on project component in a science course to assess its feasibility for a national-scale deployment, ensure data reliability, and improve local education. The researchers trained schoolteachers and selected high school students to use the field kit, and the teachers incorporated deployment of the field kit into their courses, teaching students about lead, its origin, and its health impacts. Special care was taken to provide the students with lab and field safety instructions and personal protective equipment.

The PEER team sought to validate the field kit as an affordable way to find and prioritize areas for cleanup in Peru and to empower local communities to identify lead contaminated areas and safe areas, which they otherwise would not have had the means to test. Its deployment through high school science classes offers a sustainable way to scale up these kits while improving science education and getting students excited about doing research.

Final Summary of Project Activities

After education sessions on lead contamination and the hazards towards young children, as well as on soil sampling, students were asked to take five soil or house dust samples in their community where young children play. Using the SurveyCTO app, students recorded the GPS location and photo of each sample site on a provided smartphone. Teachers supervised the soil analysis to determine the lead level. The kit uses a glycine solution at pH 1.5 for extraction and the addition of sodium rhodizonate to produce a purple color, categorized as low, medium, or high in intensity. As part of this educational module, students created maps of soil lead and presented them to their community, along with information about lead, its risks, and how to minimize the exposure of infants.

The researchers did additional XRF analysis on the samples. Out of a total of 3,674 samples, high-school students or CREEH staff recorded a visual reading of low or medium for 3,495 (95%) of the extracts. For 3,054 (87%) of the extracts with low or medium readings, XRF analysis indicated a concentration no higher than 200 ppm extractable Pb. Within the remaining 179 (5% of the total) samples for which a high visual reading was recorded, the dilution-corrected extractable Pb concentration measured by XRF was >200 ppm for 74 (41%) extracts. Low and medium kit readings therefore reliably classify soil as posing limited risk, whereas high kit readings overestimate the risk of Pb exposure by about a factor of two. The highest risk sites were the Cerro de Pasco mine and the semi-industrial Ate neighborhood of Lima, where the highest percentage of high intensity kit readings were recorded.

The researchers and teachers saw a surge in student interest in science, evident in their initiative to collect soil samples, ascertain lead levels, and devise innovative remediation plans for their communities. The project was featured in a national science fair by the third-year secondary school students of teacher Fernando Belaunde Terry and was presented at the 2019 Fall Meeting of the American Geophysical Union.

As for outreach and broader impacts, the "Lead Free Kids - Peru" project has garnered substantial interest from influential institutions, fostering a collaborative effort toward implementing impactful actions based on the project's findings. Representatives from the ministries of the environment, health, and education have shown keen interest in leveraging the project's results. The project's potential for scaling up has caught the attention of the CTel Special Popularization Program at CONCYTEC, the Peruvian National Council for Science, Technology, and Innovation. They aim to expand the project's implementation with the support of corporate social responsibility support.

Publication

J. Ponce Canchihuamán, E. Palacios, P. Ponce, J. Languasco, W. Mormontoy, F. Landes, and A. van Geen. 2019. Soil testing for lead by high-school students in several Peruvian towns. Abstract #GH13A-1052, presented at the American Geophysical Union, Fall Meeting 2019.