Inventory of Contaminated Schools
From 2019 through 2025, the EHC assessed school grounds for heavy metal contamination related to historic mining activities across various departments of Peru. Thirty schools or sites immediately adjacent to them were found to have soil contamination above Peruvian screening values established under Supreme Decree No. 011-2017-MINAM for residential/park land use.
In this document, contamination refers specifically to arsenic (As), mercury (Hg), and/or lead (Pb) exceeding their respective Environmental Quality Standards (ECAs). These three metals were chosen due to their prevalence at Peruvian mining and refining sites and their well-documented toxicity. Other metals — including cadmium — may also be elevated at affected locations, as is common with legacy mining contamination.
30
~2,154
6 years
3
Note: Two schools had samples collected immediately adjacent to — rather than directly from — the school property. Contamination in adjacent soils suggests the school grounds themselves may be affected and warrant further assessment.
Assessment objectives
- Determine whether contamination from historic refining operations has left heavy metals in school soil.
- Assess concentrations of As, Hg, and Pb in soil where children and staff are exposed.
- Evaluate the level of contamination and associated health risk, and provide recommendations to school staff and administrators.
- Produce a project-wide ranking to help federal and local agencies prioritize remedial action.
Analytical methods
Samples were collected and analyzed using three approaches depending on site conditions:
Field portable XRF
The primary method — rapid on-site screening using x-ray fluorescence.
Atomic absorption spectroscopy
Lab analysis by Cetox Lab in Lima for confirmation and detailed results.
ICP-AES (DIGESA)
Peru's DIGESA collected and analyzed samples in a fixed lab using inductively coupled atomic emission spectroscopy; results are incorporated into this evaluation.
Ranking methodology
1Each sample result was compared to the ECA for As, Hg, and Pb. Schools with all results below ECAs were screened out as uncontaminated.
2Maximum concentrations of each metal were identified for each school (sample counts ranged from 1 to 12 per site).
3Maximum concentrations were multiplied by the respective ECA to generate a risk number — the higher the concentration, the higher the risk.
4Risk numbers were summed into a total risk score, and schools were ranked from highest risk (1) to lowest risk (30).
Confidence Note: Schools with only 1–2 samples provide less certainty about overall contamination extent and require additional evaluation before final decisions are made. School population data was collected but not included in the ranking — a smaller enrollment does not reduce the need for evaluation or remediation.
Key findings
Contamination Type
High-risk Sites
Vulnerable Populations
Exposure Scale
Conclusions and recommendations
Each contaminated school has a detailed individual report with site-specific conclusions and recommendations. In most cases, schools should receive remedial action — capping or removing contaminated soil, restricting access to affected areas, or rebuilding structures made with contaminated materials.
The EHC believes immediate, relatively simple actions — such as limiting where children play — can be taken at all contaminated schools without waiting for full remediation. For schools with several sample results, action can begin now.
- Conduct soil sampling at all Peruvian schools that may have been impacted by historic or current mining or mineral refining activity.
- Assess soil at schools planned for construction or currently under construction in mining zones across Peru.