Contamination status of Alternaria toxins in commercially available wheat flour and products from Chongqing (2025) and dietary exposure risk assessment.

This study investigated the contamination levels of four Alternaria toxins, in wheat flour and its products marketed in Chongqing (2025), using isotope dilution-liquid chromatography-tandem mass spectrometry. Based on dietary consumption data and body weight parameters stratified by gender and age groups from the 2015-2017 China National Nutrition and Health Surveillance Report, the estimated daily intake (EDI) for the population was calculated using a point assessment model. Risk characterisation was performed by comparing EDI values with the threshold of toxicological concern (TTC) established by the European Food Safety Authority (EFSA). Among the 105 samples analysed, tenuazonic acid (TeA) and tentoxin (TEN) were detected in 100% and 98.1% of samples, with mean concentrations of 27.3 µg/kg and 4.0 µg/kg, respectively. Alternariol monomethyl ether (AME) and alternariol (AOH) were less frequent, with detection rates of 43.8% and 2.9%. TeA and TEN levels were highest in raw wheat flour and generally lower in processed products. Geographically, the contamination levels in southeastern Chongqing were significantly higher than those in other surveyed areas. Dietary exposure assessment indicated that the EDI of TeA and TEN were far below the TTC, suggesting acceptable health risks. However, the EDI of AME at the 95th percentile (P95) exceeded the TTC by a factor of 4.4-8.2. The detection rates of AME and AOH are relatively low while the widespread occurrence of TeA and TEN in wheat flour and its products sold from Chongqing poses a manageable risk at present. Nevertheless, given the high detection rates, thermal stability, and the genotoxic potential of certain toxins, attention should still be paid to the risks associated with long-term low-dose co-exposure. It is recommended that national maximum residue limits be established as soon as possible.