Quantitative analysis and dietary risk assessment of aflatoxins in Chinese post-fermented dark tea.

Recently, mycotoxins safety in Chinese post-fermented teas has attracted much attention because it is still controversial whether environmental fungi in the teas are able to produce aflatoxins. In this study, a rapid and selective analytical method based on immunoaffinity column (IAC) cleaning coupled with liquid chromatography-mass spectrometry (LC-MS) was developed to quantify four aflatoxins (B, B G and G) in post-fermented teas. Recoveries ranged from 80.8 to 92.2% with relative standard deviation less than 3%. The limits of detection and quantification were 0.109-0.348 μg kg and 0.364-1.159 μg kg, respectively. Two out of 158 samples were positive for aflatoxins examination (occurrence rate 1.27%). The deterministic assessment for the maximal aflatoxins exposure under upper bound was 9.19 × 10 μg kg day from heavy exposure consumers (≥50 year age group), but the exposure was lower than the JECFA acceptable value of 1.0 ng kg day on liver risk. Probabilistic assessment showed that the upper bound 95th percentile carcinogenic risk value for the 318 consumers (Yunnan China and Ulan Bator Mongolia) was 1.75 × 10, and for heavy exposure consumers was 2.4 × 10, and the values equally below the acceptable carcinogenic risk level.