10 years of investigations on Cerro de Pasco case study

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Between 2009 and 2019, Source International is investigating how mining activities are polluting and impacting the health of local people in the Peruvian city of Cerro de Pasco.

Several studies (both government and non-government entities) conducted in Cerro de Pasco across the years have shown both the extended environmental pollution and the health effects on the community, especially on children.


SOURCE INTERNATIONAL observed how water river pollution, despite the extraction phase stop in 2013, reduced but it is persisting with high heavy metals concentrations that are harmful for human consumption, ecosystem protection, and agricultural purpose.

School and recreative urban parks presented a high level of lead, arsenic, mercury, and cadmium in soil that are upper than the Peruvian law. Those compounds are extremely dangerous for humans because toxic and carcinogenic. No heavy metals higher than the national standard have been observed in the control site (40 km far from Cerro de Pasco), demonstrating how the main pollution source remains the mining activities that include re-processing of mining waste and the mining waste disposal impact. Contaminated soils represent an important exposure path for children by ingestion, inhalation of suspended particles, and through contact skin.

                                                      Urban Park closed to a giant mining waste disposal. Photo by Stefano Sbrulli

Land used for agricultural (potato) and cattle grazing (llama, alpaca, sheep, and cow) near the mining waste disposals and near to the river that flow close to the mine showed the important level of lead, arsenic, mercury, and cadmium. This represents a serious health risk linked to the pollutants' path through the food chain up to humans.

The meat of some cattle samples collected and analyzed presented 10 times more lead than the FAO and OMS standard.


A case-control study has been applied to assess the different degrees of exposure to heavy metals in two child populations: Paraghsa (exposed) and Carhuamayo (not exposed-40 km far from Cerro de Pasco).

Hair study

17 heavy metals of the 21 analyzed have been encountered in children's hair in the exposed community, against 7 heavy metals detected in the control group.

The mean concentrations of lead in hair in children of exposing community exceeded 6 times the no-exposed community; cadmium exceeded it 2 times, arsenic 3 times. Furthermore, lead turned out to be 46 times higher than the standard established by the MicroTrace German laboratory who works with hair analysis for decades.

Compared with the previous hair analysis conducted in 2016, we observed an increase of many heavy metals concentrations from 2016 to 2018. Furthermore, thanks to the separate length ( roots and long hair) of hair analyzed we have been able to track children's exposure in previous years demonstrating a peak of pollutants in hair in 2017. A possible cause of the increase of human exposure lies in the movement of the dismantling from the mining waste disposals to be processed into the industrial plant which began the operations in June 2015.

Clinic forensic investigation

Parallel to the analysis of hair samples as a possible biomarker of metal exposure, a clinical investigation of exposed children was carried out. For this, complete physical examinations, external examinations, and anamnesis (clinical history) of both cohorts were performed to assess a potential correlation between chronic exposure to heavy metals and the development of some clinical manifestations that may be associated.

Several health manifestations as depression, irritability, blu gum lines, white nails lines, calluses, conjunctivitis among others, have been widely observed in the exposed community compared with very few cases in the not exposed community.

Strong evidence of the direct impact of mining activities.


We send all these data and studies to the Norvegian Pension Funds in December 2019 and we are waiting about their decision to divest from the mining company according to this strong evidences of ecocide and human rights violations.


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