Lithium occurrence in food produced in the surroundings of the C-57 mine

The interest in lithium (Li) has grown over the last decades, mainly due to its application in electronic products and electric vehicles (2020, Kaunda). Li is not considered an essential nutrient for vital functions, and at high levels could be toxic to humans (2021, Bolan). Portugal is a country with active and prospective Li mining concessions. This pioneering study aims to evaluate the Li contents in cabbages and irrigation water in rural areas near the C-57 Li pegmatite mine in Gonçalo (Guarda district, Portugal). The distance between the sampling locations and the mine classified them as near (up to 1,5 km, L1) or far (between 2 and 8,5 km, L2) to the mine. Twelve subsistence farms constituted the sampling plan in both locations. Three cabbages were collected in each farm (n=72) and analysed as a laboratory pool (n=24); water samples were also collected at each location. Li amounts in the selected samples were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and cabbage analysis was preceded by microwave-closed vessel acid digestion. Analytical procedures were conducted following the quality assurance requirements described in the ISO/IEC 17025:2017 standard. The Li concentration in each location was expressed, as the average of three replicates, in μg/kg of fresh weight for cabbages and μg/l for water. The results from L1 are, on average, higher than those found in L2. On cabbage samples, the Li ranged from 44.4 ± 0.7 μg/kg to 1626 ± 32 μg/kg μg/kg in L1 and from 33 ± 1 μg/kg to 509 ± 19 μg/kg in L2; on irrigation water the Li levels ranged from 6.1 ± 0.1 μg/l to 36.6 ± 0.4 μg/l in L1 and from 2.40 ± 0.04 μg/l to 16.7 ± 0.4 μg/l in L2. The results show the influence of the geogenic lithium resource proximity.