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-1, B-2, G(1) and G(2)) 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 mu g kg(-1) and 0.364-1.159 mu g kg(-1), 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 x 10(-6) mu g kg(-1) day(-1) from heavy exposure consumers (>= 50 year age group), but the exposure was lower than the JECFA acceptable value of 1.0 ng kg(-1) day(-1) 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 x 10(-7), and for heavy exposure consumers was 2.4 x 10(-7), and the values equally below the acceptable carcinogenic risk level.