The main aim of this study is to develop tools to improve food safety, human and animal health protection in Portugal.

This project will focus on the assessment of soil-soil solution-crops models of potentially toxic elements (PTEs) to improve risk assessment tools in agricultural areas. We will apply recently developed concepts to assess the biogeochemical reactivity of contaminants in soils and the solid:solution partition of PTEs using Freundlich-type empirical models. These models will be used to assess the transfer of contaminants along feed and food supply chains and to evaluate the impact of soil contamination on feed and food quality in Portugal. Finally, the derived soil-plant transfer functions will be applied to back-calculate critical thresholds of PTEs in Portuguese agricultural soils considering legal standards for feedstuff and food.

Awareness has grown that soil is an important factor in the feed and food supply chain in order to deliver safe and high-quality products. Uptake by crops, fodder, animals, and ultimately the consumer depends on soil properties, animal properties, plant properties, and consumption patterns. Most human exposure assessments concerning the dietary intake of PTEs are based on measured concentrations in food products. However, for specific regions, monitoring data are often not available. Information on the impacts of soil contamination in agricultural areas in Portugal and food chain risks to human and animal health is very scarce which urges the need to perform this study. Solid-solution portionin relationships and availability of metals such as Cd, Zn, Pb and Cu for plant uptake have been studied, particularly in other countries such as the Netherlands and UK. However, for other contaminants (such as As, Hg, Co, Sb, Ba and U) known to occur in high concentrations in certain Portuguese soils little information is available.

This project will consider a large array of PTEs (As, Hg, Cu, Pb, Zn, Cd, Ni, Cr, Co, Ba, U, Fe, Mn, Al, Sb, Li, Be, Se, B and Mo) with particular emphasis on less studied contaminants. The research plan will include five main tasks:

o Task 1: Sampling of water, soils, crops and animal products in agricultural areas in Portugal

o Task 2: Chemical extractions of soils and analysis of water, plant and animal products samples

o Task 3: Derivation of soil-soil solution-plants empirical models and soil-plants-animals relationships

o Task 4: Calculation of daily intakes of PTEs for animals and humans and evaluation of potential risks to animal and human health

o Task 5: Derivation of critical limits of PTEs for agricultural soils in Portugal using improved soil-crop models

The most important milestones of the project are the collection and chemical characterisation of samples of water, soils, plants (feed and food crops) and animal products (kidney, liver, muscle and hair of cow and sheep) from agricultural fields in Portugal; the derivation of calibrated empirical models and plant-animal bioaccumulation factors (BAFs); the estimation of dietary exposure of PTEs for animals and humans; and the derivation of critical limits of PTEs in agricultural soils in Portugal.

Since it would be impossible to collect samples in the entire country within the scope of such Project, target areas geographically distributed around the country will be selected. These areas will include both agricultural fields that are not expected to be affected by known pollution sources and soils that are known to be impacted by industrial and mining activities. The project is designed in such a way that the approach developed can also be applied to other regions in the future, using region-specific data.

Since at the moment there is still no contaminated land management framework in place in Portugal the findings of this Project can serve as a first step towards the development of soil quality criteria for agricultural areas. The results obtained can also serve as a conceptual basis for future risk assessment studies to be conducted in contaminated sites in Portugal and elsewhere.

The Project will involve researchers from CESAM - Centre for Environmental and Marine Studies (University of Aveiro). Researchers from the Center for Pharmaceutical Studies (University of Coimbra) will also participate in the project. An international consultant with experience in contaminant uptake, soil-plant relationships and risk assessment will provide advice to researchers throughout the project.

This multidisciplinary team combines expertise on analysis of PTEs in several matrices and environmental quality assessments; experience in the geochemical characterisation of soil matrices; and the required expertise on plant uptake processes, biochemistry and toxicology.

Sónia Alexandra Morais Rodrigues
Researcher