Oxidative damage associated with exposure to heavy metals present in topsoils in central Chile.

Exposure to heavy metals may cause the overproduction of reactive oxygen species, generating oxidative stress and consequently, various harms to human health. The soil surrounding the Ventanas Industrial Complex, in Puchuncaví and Quintero municipal districts on the central Chilean coast, contains heavy metal concentrations (As, Cu, Pb, Zn, among others) that far exceed the maximum permissible levels established by Italian soil standards (used as a reference). This study aimed to investigate the potential association between heavy metal exposure in humans and the levels of oxidative stress biomarkers in inhabitants of these locations. We took blood samples from 140 adults living in sites with high concentrations of heavy metals in the soil and compared them with blood samples from 140 adults living in areas with normal heavy metal concentrations. We assessed lipid peroxidation, damage to genetic material, and Total Antioxidant Capacity in these blood samples. Our results indicate an association between oxidative damage and heavy metal exposure, where the inhabitants living in exposed areas have a higher level of DNA damage compared with those living in control areas. Given that DNA damage is one of the main factors in carcinogenesis, these results are of interest, both for public health and for public policies aimed at limiting human exposure to environmental pollution.

Arsenic concentration in topsoil of central Chile is associated with aberrant methylation of P53 gene in human blood cells: a cross-sectional study.

Gene expression can be modified in people who are chronically exposed to high concentrations of heavy metals. The soil surrounding the Ventanas Industrial Complex, located on the coastal zone of Puchuncaví and Quintero townships (Chile), contain heavy metal concentrations (As, Cu, Pb, Zn, among others) that far exceed international standards. The aim of this study was to determine the potential association of the heavy metals in soils, especially arsenic, with the status of methylation of four tumor suppressor genes in permanent residents in those townships. To study the methylation status in genes p53, p16, APC, and RASSF1A, we took blood samples from adults living in areas near the industrial complex for at least 5 years and compared it to blood samples from adults living in areas with normal heavy metal concentrations of soils. Results indicated that inhabitants of an area with high levels of heavy metals in soil have a significantly higher proportion of methylation in the promoter region of the p53 tumor suppressor gene compared with control areas (p-value: 0.0035). This is the first study to consider associations between heavy metal exposure in humans and aberrant DNA methylation in Chile. Our results suggest more research to support consistent decision-making on processes of environmental remediation or prevention of exposure.

Advanced determination of the spatial gradient of human health risk and ecological risk from exposure to As, Cu, Pb, and Zn in soils near the Ventanas Industrial Complex (Puchuncaví, Chile).

The townships of Puchuncaví and Quintero, on the coast of central Chile, have soils contaminated by atmospheric deposition of sulfur dioxide and trace elements from the nearby Ventanas Industrial Complex. The purpose of this study was to evaluate potential human health and ecological risks, by determining the spatial distribution of soil total concentrations arsenic (As), copper (Cu), lead (Pb), and zinc (Zn) in these townships. Total concentrations of these elements were determined in 245 topsoil samples, used to generate continuous distribution maps. The background concentrations of Cu, As, Pb, and Zn in the studied soils were 100, 16, 35, and 122 mg kg-1, respectively. The concentrations of Cu, As, and Pb were positively correlated with each other, suggesting that their source is the Ventanas copper smelter. On the other hand, correlations for Zn were weaker than for other trace elements, suggesting low impact of the Ventanas copper smelter on spatial distribution of Zn. Indeed, only 6% of the study area exhibited Zn concentrations above the background level. In contrast, 77, 32 and 35% of the study area presented Cu, As, and Pb concentrations, respectively, above the background level. The carcinogenic risk due to exposure to As was above the threshold value of 10-04 in the population of young children (1-5 years old) on 27% of the study area. These risk values are classified as unacceptable, which require specific intervention by the Chilean government. Based on the estimated concentrations of exchangeable Cu, 10, 15, and 75% of the study area exhibited high, medium, and low phytotoxicity risk, respectively.