Chilean regulations on metal-polluted soils: The need to advance fromadapting foreign laws towards developing sovereign legislation

Chile as a major international Cu producer faces serious soil contamination issues in mining areas. CurrentlyChile does not have any specific law governing the maximum permissible concentrations of metals in soils toprotect ecosystems and human health. Chile heavily relies on the use of environmental laws of 14 foreigncountries; the choice of the country depends on the similarity of its environmental conditions with those in Chile.In this study, we used an online database to compare the similarity of Chilean rocks to those in foreign countries.Likewise, we performed soil sampling and determined the background concentrations of Cu, As, Pb, and Zn insoils of the Aconcagua basin, the largest river basin in the Valparaiso Region of central Chile. The results showedthat geochemical patterns in Chile have the greatest resemblance to New Zealand, Mexico, and Italy. Thebackground Cu concentration in the Aconcagua basin (134 mg kg−1) exceeded the legislated limits of NewZealand (100 mg kg−1) and Italy (120 mg kg−1), whereas the background Zn concentration (200 mg kg−1)exceeded the legislated limit of Italy (150 mg kg−1). Due to the elevated natural abundance of Cu and Zn inChile, international laws should not be applied in Chile for the assessment of soil contamination. In addition, weassessed ecological risk using the results of our previous studies obtained by analyzing nativefield-contaminatedsoils of the Valparaiso region. In the Aconcagua basin, Cu posed high risk for plants in 11% of the samples,whereas As posed high risk for earthworms in 48% of the samples. We suggest that future studies are required tosearch for other organisms that can serve as biomarkers of metal toxicity because our previous studies werelimited to plants and earthworms. Importantly, As posed high risk to human health in 25% of the samples in ourstudy. There is a need for future studies to demonstrate empirically an association between soil As and children'sblood As in order to establish the national threshold values of soil As to protect human health. We conclude thatthere is an urgent need in Chile to advance from the current approach of adapting foreign laws to developingChilean sovereign environmental legislation.
Copper, Zinc, Arsenic, Lead, Rock types, Background concentrations