Risk assessment of heavy metals consumption through onion on human health in Iran

Considering the importance of onions consumption in the household diet, controlling of heavy elements' concentration in foodstuffs is important to ensure the safety of an individual's health. This study aimed to evaluate the risk of heavy metals through onion consumption on human health. In this cross-sectional experimental study, 22 onion samples with varieties red, yellow, and white in the two autumn and winter seasons in 2020 were randomly collected from the different provinces of Kurdistan, Hamedan, and Kermanshah. The concentrations of heavy metals were evaluated with an atomic absorption spectrometer. The risks of human health were evaluated by the hazard quotient (HQ) and the obtained results were analyzed with one-way ANOVA and one sample t-test. The obtained findings demonstrated that all collected samples contained heavy metals. For example, the cadmium (Cd) concentration in onion samples in the province of West Azerbaijan, Kurdistan, Hormozgan, Isfahan, and Zanjan was 526.49, 274.49, 69.77, 67.39, 65.69 µg kg^-1, respectively. While the standard specified in Iran for the concentration of Cd in onions is 50 μg kg^-1. However, the rate of lead (Pb) contamination in samples collected from Isfahan, Hormozgan, Zanjan Khuzestan, Tehran (Varamin) was 296.50, 266.71, 261.49, 215.64, 106.19 µg kg^-1, respectively, which less than maximum allowable limit recommended by WHO-FAO (300 µg kg^-1). The HQ for non-cancerous diseases for Cd and Pb were 8.6 × 10^-2 and 1.6 × 10^-1, respectively, and the probability of carcinogenic risk for Pb (8.1 × 10^-4) was at the level of acceptable. There is no concern about the non-carcinogenic diseases and carcinogenic risk of consuming heavy metals in onion. Therefore, for optimal management and prevention of further pollution, it is recommended to study the origin and determine the amounts of heavy metals for their potential contamination of foodstuffs from the region's soil, water, and dust.