Heavy metals risk assessment in vegetable oils in Iran: A systematic review, and meta-analysis

The risks associated with heavy metals (HMs) in oil are important for health. This study investigated and evaluated the concentration of HMs in oils examined in Iranian studies using a systematic review method. First, published articles were identified in the Science Direct, PubMed, Scopus, and Web of Science databases. The concentrations of HMs were extracted from reliable papers and subjected to risk assessments. This research utilized pooled concentration estimates from the selected articles, integrating them with a Monte Carlo probabilistic framework of 10,000 iterations to assess the uncertainty in both non-carcinogenic and carcinogenic risks for adults and children. After screening and quality control of the articles, 16 valid articles were identified. Rapeseed oil contained the highest amounts of Cd and Cu, soybean oil exhibited the highest level of Fe, corn oil had the lowest amount of As, and olive oil showed the highest levels of Ni, Zn, and Pb. The non-carcinogenic health risk assessment of HMs indicated that the hierarchy of metals, according to the Target Hazard Quotient (THQ) for the exposed population, was as follows: As > Cd > Pb > Ni > Zn > Fe > Cu. Furthermore, THQ of As, Cd, Cu, Fe, Ni, Pb, and Zn for adults were 2.947, 2.187, 0.115, 0.125, 1.321, 1.922, and 0.244, while THQ for children were 6.957, 5.200, 0.264, 0.292, 3.078, 4.414, and 0.566. The lifetime cancer risk (LTCR) for As, Cd, and Pb in Vegetable Oils (VOs) was within the permissible range. Moreover, the carcinogenic risk from As (4.361 × 10^- 3) was found to be 1.3 times higher than that of Cd (3.640 × 10^- 3) and 23.8 times higher than that of Pb (1.891 × 10^- 4). It can be concluded that due to the toxic effects of HMs in VOs, we should be more serious about reducing the risk and pollution levels in this region.

The online version contains supplementary material available at 10.1007/s40201-026-00991-3.