Essential and toxic metals in taros (Colocasia esculenta) cultivated in the Canary Islands (Spain): evaluation of content and estimate of daily intake.

Abstract

Taros are a staple in the diet of many people around the world, and they are an excellent source of minerals. Monitoring the levels of metals in food provides basic information that is useful from the perspectives of safety, regulation, and nutrition. Forty-two samples of taros were randomly obtained from supermarkets, vegetable markets, and farmer's plots on the island of Tenerife (Canary Islands, Spain). The edible portion (pulp) was the only part considered for analysis. Flame atomic absorption spectrometry (FAAS) was used to determine the contents of Na, K, Ca, Mg, Cu, Fe, Mn, and Zn. The levels of Cr, Ni, Cd, and Pb were determined using graphite furnace atomic absorption spectrometry (GFAAS). Mean concentrations (mg/kg) were 565.6 Na, 2947 K, 231.4 Ca, 364.5 Mg, 1.224 Cu, 3.818 Fe, 1.408 Mn, 2.242 Zn, 0.044 Cr, 0.021 Ni, 0.003 Cd, and 0.006 Pb. The mean concentrations of Cd and Pb were well below the accepted European Commission limits (0.1 mg/kg weight for both metals, respectively). Daily consumption of taro (10.41 g taro/person/day) contributes to the dietary intake of essential metals and trace elements, mainly Mg (1.265% in adult women and 1.084% in adult men) and Cu (1.182% for adult men and women). The average daily intakes of Cd (0.031 μg/day) and Pb (0.062 μg/day) from taro were below the legislated respective tolerable weekly intakes (TWIs). Thus, the samples analyzed were considered safe to eat based on their metal concentrations and legislated allowable intakes.