Abstract: [Objective] The contamination of heavy metals in walnuts (Juglans regia) from the main producing areas of Yunnan, Guizhou and Sichuan Provinces was investigated. Based on the data,the human health risks of heavy metals intake from the walnut consumption were evaluated, in order to provide scientific basis for walnut production and consumer healthy consumption.[Method] A total of 204 batch walnut samples were collected from the main producing areas of Yunnan, Guizhou and Sichuan Provinces.The contents of Pb, Cd and As in the samples were determined by graphite furnace atomic absorption spectrometry (GF-AAS) and atomic fluorescence spectrometry (AFS). Then the single factor pollution index and Nemerow multi-factor index were used to evaluate the levels of heavy metals in walnuts. In addition, combined with the Chinese resident's consumption for walnut and their weight information,the dietary risk and carcinogenic risk of As, Pb and Cd in walnuts were evaluated by a health risk model from the US Environmental Protection Agency (USEPA).[Result] The result showed that the concentrations of As, Pb and Cd in the tested samples were ND-0.064 mg·kg^-1, ND-0.095 mg·kg^-1 and ND-0.017 mg·kg^-1, respectively. The average contents of the three heavy metals in the tested walnuts did not exceed the limits of the standard LY/T 1777-2008 "Forest food-General rule for quality safety", which indicated that the pollution status of As, Pb and Cd in walnuts from the three provinces was generally lighter. In addition, the single factor pollution index of heavy metals in the walnut samples was Pb > As > Cd. The order for heavy metal pollution of walnut samples in the three provinces according to the Nemerow multi-factor index was Sichuan Province > Yunnan Province > Guizhou Province, all the comprehensive pollution index were less than 0.15, which was far less than the warning value of 1.[Conclusion] Pb and As were the major heavy metal contaminants in the walnut samples of the three provinces, and the risk for human health was Pb > As > Cd.The potential health risk through walnut consumption for children was 25 times higher than that of for adults. However, the dietary risk and carcinogenic risk were lower than the risk threshold for children and adults, and the risks were still within acceptable level.

Key words: walnuts, heavy mental, health risk assessment, food safety