Edible Salt: A Possible Source of Heavy Metal Intake in Sri Lanka

Abstract

Salt is an essential component in the human diet Salt contains minute quantities of essential and non-essential metal elements, other than sodium and chloride. Salt requirement of Sri Lanka is almost entirely fulfilled by seawater processing in the salterns located in semi-arid regions (Northwestern and South-southeastern) of the country. The surface circulation pattern of the seawater around Sri Lanka indicates possible contaminant loading and concentration in seawater. This may affect the quality of the edible salt produced from the seawater. Thus, the current study was conducted to investigate the amount of heavy metals in commercially available table salt products in Sri Lanka. Two salt samples representing two major salterns (located in South-southeastern and the Northwestern region) were randomly selected from the local market and analyzed for Cu, Fe, Pb, Cd, Cr, and Zn levels using Atomic Absorption Spectroscopy. Only Fe and Cd were detected in both salt samples, and higher concentrations of both the ions were observed in the salt produced in the South-southeastern region than the Northwestern region. This could be linked with swirling and mixing of seawater currents, loaded with contaminants while moving along the west coast, in the south-southeastern region resulting in concentration of metal elements in seawater. The estimated Fe intakes with salt (0.059 and 0.092 mg per 6 g of salt per day, for Salt A and B, respectively) was less than the daily requirement of 15 mg specified by the WHO, whereas the estimated daily Cd intakes from salt A and B (0.018 and 0.024 mg per 6 g of salt) appeared to be similar to the provisional tolerable monthly intake of 0.025 mg/kg of body weight. Therefore, findings of this inceptive study suggest that detailed investigation on the composition of salt products including temporal and geographical variability, possible contaminations in the production process and daily dietary salt intake levels would add valuable information to the avenues of heavy-metal intake.