Trace Elements and Security of Foods Produced in Urban Community Gardens, Curitiba, PR, Brazil

Abstract

Urban gardens have emerged as a new global tendency for supporting food security, and has therefore become the focus of diverse studies and attracted the attention of public administrations as an option for sustainable food production. Vegetable crops cultivated under conditions of high exposure to contaminants found in large urban centers, however, tend to accumulate toxic compounds, such as, trace elements, and insert them into human foods and the trophic chain. We therefore evaluated the food security of vegetables (lettuce and collard greens) produced in urban gardens in the Metropolitan region of Curitiba City (Brazil) in terms of the presence of trace elements. Assays were performed in plants harvested from four urban gardens as well as an agroecology site (control). We also assayed for trace elements in the garden soils and the irrigation water used for their production. Both the soils and the irrigation waters had trace element concentrations within the maximum recommended limits, and were therefore not vehicles of contamination. Similarly, trace element concentrations identified in the biomasses of lettuce and collard greens plants grown in the control area, as well as the four urban gardens, were below the maximum limits recommended for leafy vegetables. The vegetables produced in the urban gardens and the agroecology area are considered safe for human consumption.