Toxic metal contamination in edible salts and its attributed human health risks: a systematic review and meta-analysis

Abstract

Sodium chloride, commonly referred to as table salt, is the most widely utilized seasoning in culinary applications. Nevertheless, the most of oral salts used contain impurities. Arsenic (As), mercury (Hg), cadmium (Cd), and lead (Pb) are the most common impurities found in salt. In this meta-analysis, we examined the status of Pb, Hg, Cd, and As in the salt sample consumed in Iran. For this purpose, a complete search was carried out in English (Scopus, PubMed, and Web of Science) and Persian (Scientific Information Database, IranMedex, and Magiran) electronic databases to identify related articles published by July 2024. In the present meta-analysis, twelve studies with a total number of 610 salt samples were included in the analyses. According to the findings, the pooled mean levels of Hg, Pb, As, and Cd were 0.06 µg/g (95% CI: 0.04–0.08), 2.98 µg/g (95% CI: 2.35–3.61), 0.42 µg/g (95% CI: 0.19–0.66), and 0.71 µg/g (95% CI: 0.76–1.04), respectively. The levels of Cd and Pb in rock salt are higher than those found in the sea and refined salt. The hazard index (HI) values were recorded as 0.41 (95% CI: 0.235 to 0.588) for men, 0.428 (95% CI: 0.246 to 0.614) for women, and 0.594 (95% CI: 0.341 to 0.853) for children. The results of the present study show higher levels of Pb and Cd in unrefined salt compared to refined salt. Additionally, the health risk associated with exposure to Cd, Pb, As, and Hg through salt consumption is negligible in Iranian adults.