Soil-to-plant transfer of heavy metals and an assessment of human health risks in vegetable-producing areas of São Paulo state

Abstract

The concern regarding the presence and accumulation of potentially toxic elements (mainly heavy metals) in soil and consequently in plants has been steady due to the adverse effects they may cause to the environment and human health. One of the main routes of exposure to heavy metals (MP) for the majority of the population is through ingestion of food, but there are few studies related to the concentrations of MPs in soils and plants of humid tropical regions, especially in Brazil. The index most commonly used to estimate the accumulation of heavy metals in plants and subsequent human exposure by vegetable is bioconcentration factor (BCF), which is the ratio between the concentration of MPs in edible parts of the plants and the total concentration of metal in the soil. However, the BCF does not adequately describe the mechanism of soil-plant transfer of metals, and the use of relationships involving the main soil properties that influence the willingness of MPs to plants may explain the soil-plant relations in more detail. The state of São Paulo is the largest consumer market, besides being the largest and most diverse vegetable crop producer in Brazil. Thus, research is needed on the concentration of MPs in soils and vegetables, for evaluation of their quality over the limits established by law. Likewise, it is important to establish the critical limits of these elements in soils, using models of risk assessment to human health, based on results that represent the real condition of the soil of São Paulo. The National Institute of Public Health and Environment of the Netherlands (RIVM) is a center of excellence in research related to soil-plant transfer of potentially toxic elements and ecotoxicological risk assessment and human health for several years and conducts studies to support the government Dutch in making decisions about the guiding values for soil and groundwater that country. The RIVM developed mathematical model C-Soil and advised the Company of Environmental Sanitation Technology (Cetesb) to develop Table Guiding Values of SP. Cetesb is the environmental agency of the state of São Paulo, responsible for the control, supervision, monitoring and licensing of pollution-generating activities.This work aims to: (i) calculate the risk to human health due to the consumption of vegetables, (ii) derive the soil-plant relations and calculate the critical concentration of soil Cd, Cu, Ni, Pb and Zn, using the Model C-Soil. (AU)