Tracing the source of Brazil nut contamination using advanced mass spectrometric methods

Brazil nut trees (Bertholletia excelsa) are a protected species that is vital to the forest economies of Amazonian Bolivia, Peru and Brazil, and cannot be grown in plantations. Nuts are harvested from wild trees in natural forest. The majority of nuts are exported to the EU, UK and USA, providing the only regular income for many rural households in the Western Amazon region and guaranteeing the survival of the forests where trees grow. As part of import controls to the EU, Brazil nut processing plants are required to certify levels of methyl bromide, a pesticide that is banned in many countries due to its harmful environmental impacts. Methyl bromide is not known to be used in any of the forests, or adjacent agricultural landscapes where Brazil Nuts are grown, yet levels of 24 to 100 ppb have been reported in Brazil nuts. At 25 ppm or above nuts no longer qualify as 'organic', despite being wild harvested in natural forest away from agrochemical use of methyl bromide. At or above 50 ppm, nuts no longer qualify as fit for human consumption. This impacts considerably on the commodity's price and it is perceived by processing and export companies as the main threat to their industry (greater than climate change or deforestation). The loss of this mainstay on the local community would have devastating impact on the forests as their main value would switch to soya, cattle, or timber, which would entail deforestation.

This project will focus on the development of mass spectrometry techniques and remote sampling methods to trace the source of methyl bromide. Specifically, the project will investigate the variation at different scales (in nuts, across the tree, within the surrounding forest, across the Bolivian Amazon). We will investigate whether the contamination is coming from the local environment (soil, leaf-litter, the trees themselves) or longer distance contamination stemming from pesticide use, and whether levels of methyl bromide correlate with any impact on the nutritional or health value of Brazil nuts. Finally, we will determine potential drivers in variation that could predict long-term threats or mitigation to the Brazil nut market.