Heavy metal levels in camel milk and health risk assessment: A global systematic review

Abstract

This systematic review investigates the potential toxicity of metals and metalloids, including lead (Pb), mercury (Hg), cadmium (Cd), and nickel (Ni), in raw camel milk, with a focus on health risk assessment for human consumption through the calculation of Target Hazard Quotient (THQ) and Carcinogenesis Risk (CR). From 927 initial articles, we analyzed 20 original articles, comprising 787 samples published between 2000 and 2024. Pb levels ranged from nondetectable to 1.560 mg.kg−1, while Cd levels ranged from 0.0008 to 0.800 mg.kg−1. Egypt and Saudi Arabia reported the highest levels of Pb, Ni, and Cd. Pb concentrations in milk exceeded the Codex Alimentarius recommended limit (0.020 mg.kg−1) in 10 out of 18 studies. Overall, Pb and Cd exposure through milk consumption appeared safe for humans, although THQ values exceeded 1 in two Pb studies out of 18 and in one Cd study out of 16. This study contributes to establishing an international database on toxic metal levels in camel milk, informing strategies for managing metal-related risks in milk consumption.