Seasonal Occurrence of Aflatoxin M1 in Raw Milk during a Five-Year Period in Croatia: Dietary Exposure and Risk Assessment

This study’s objective was to estimate the seasonal occurrence of aflatoxin M(1) (AFM(1)) in cow’s milk between winter 2016 and winter 2022 and to assess dietary exposure and risk assessment for the adult Croatian population. In total, 5817 cow milk samples were screened for AFM(1) concentrations using the enzyme immunoassay assay (ELISA). For confirmation purposes of AFM(1) concentration above the European Union maximum permitted level (MRL), ultra high-performance liquid chromatography with tandem mass spectrometry was performed. In 94.7% of milk samples, AFM(1) levels were below the detection limit (LOD) of the ELISA test. For 3.47% of samples, the AFM(1) was between the LOD and MRL values. Only 1.87% of all samples exceeded the MRL. The mean value of elevated AFM(1) in different seasons ranged between 59.2 ng/kg (autumn 2017) and 387.8 ng/kg (autumn 2021). The highest incidences of positive AFM(1) were determined in autumn and winter and the maximum (6.4%) was in winter 2019/2020. The largest percentage of positive samples (69.7%) was found in central Croatia. The estimated daily intakes for positive samples ranged between 0.17 and 2.82 ng/kg body weight/day. Risk assessment indicated a high level of concern during autumn and winter, especially for consumers of large amounts of milk.