BJRP 011006

A modeling framework to explore the environmental fate and health impacts of persistent organic chemicals in the Madeira river basin

Abstract

We propose collaboration between the INCT for Translational Research in the Environment and Health in the Amazon Region at the Federal University of Rio de Janeiro (UFRJ) and the Safety and Environmental Technology Research Group at the Federal Institute of Technology Zurich (ETHZ) to investigate the fate and health impacts of persistent organic chemicals (POCs) in the Amazon environment. Our proposed project has two primary goals: to compile a time-resolved database of POC measurements in the environment, biota and humans and to create a modeling framework to aid in understanding the dynamics of POCs in the Amazon environment and its local populations.

Our project will focus on four sites in the Madeira River basin. The Madeira River is a major tributary of the Amazon River, has a drainage basin that covers 20% of the area of the Amazon basin, and is a major contributor to the nutrient load of the system. It is also highly impacted by human activity, including mining, deforestation, industrial activity and the use of pesticides and biocides in agriculture and for disease control. The four sites have been chosen to exemplify characteristic Madeira River environments and these environmental impacts. The Puruzinho site is a traditional Amazonian settlement, where a small population subsists almost entirely on local sources of food and water and is thus closely tied to their environment. Previous research has shown high levels of dichlorodiphenyltrichloroethane (DDT) in human breast milk from this site, and local fish are the most likely major source. The Porto Velho site is in the capital city of Rondônia state, with a population that has exploded over the past three decades to nearly 380 thousand and a high degree of industrial and transportation activity. The Guajará site is located at the border with Bolivia, is thus influenced by a different emission pattern for POCs than sites exclusively within Brazil, and is impacted by the construction of new hydroelectric dams. Finally the Bom Futuro site is associated with a tin mine and is experiencing rapid population growth.

Compilation of the POC database at UFRJ will entail a field sampling and analysis campaign over four periods. Samples of soil, sediments, fish, breast milk and hair will be collected at each site on four occasions: during the first project year between May and July and again between November and January, and again for the same periods during the second project year. Analysis for the first three sampling periods will be used in the development, application and calibration of models at ETHZ. The primary targets for the sampling and modeling activities will be DDT and polychlorinated biphenyls (PCBs), although sample analysis will seek to include as many additional POCs as feasible.

The model framework will be based on the Puruzinho site, which has the most existing data, and will focus initially on DDT and in year two will also include PCBs. The modeling framework consists of four parts: a multi-compartment environmental fate model for the Madeira River stretch adjacent to the Puruzinho settlement, a second environmental fate model for Puruzinho Lake, a bioaccumulation model for fish, and a pharmacokinetic model for POC body burdens in humans resulting from uptake from the environment and the diet. The main outputs from the modeling framework will be mass budgets for DDT and PCBs at Puruzinho, and a human health risk assessment for DDT based on a time series of measurements in breast milk that began in 2000 and will extend to the second year of the proposed project. At the close of the project period, we will integrate our results into three major dissemination materials: a technical tutorial to be presented at UFRJ which introduces the modeling techniques, provides major results and discusses important implications for the human health risk assessment; educational materials for local communities outlining the identity and levels of contaminants found in their environment and associated health risks; and finally guidance documents for environmental management based on the findings for POCs in general and on the risk assessment for DDT in particular.

Prof. K HUNGERBUEHLER

Prof. O. MALM

Dr JP TORRES