Aflatoxin M1 Levels in Commercial Cows’ Milk in Mexico: Contamination and Carcinogenic Risk Assessment

Aflatoxin M1 (AFM1), a toxic metabolite of aflatoxin B1 (AFB1), is commonly found in cow’s milk (CM) when dairy cattle consume contaminated feed. Chronic exposure to AFM1 poses serious health risks, particularly for children. This study aimed to quantify AFM1 levels in commercial CM available in Mexico and assess the associated carcinogenic risk across six age groups. A total of 23 milk samples were collected between March and July 2023 from supermarkets and convenience stores. AFM1 was measured using high-performance liquid chromatography (HPLC). Estimated daily intake (EDI), carcinogenic risk index (CRI), and Monte Carlo simulations (MCS) to model exposure were employed. AFM1 was detected in all samples, with 80% exceeding the legal limits set by Mexican and European regulations. The highest CRI values were observed in children aged 1–4 years (CRI > 5 × 103), indicating an elevated risk. There were no statistically significant differences in AFM1 concentration among different milk or thermal treatments. A cluster analysis revealed patterns related to AFM1 content, price, and processing methods. The widespread detection of AFM1 raises a public health concern, especially for vulnerable populations. This underscores the need for targeted regulatory strategies and improved control of aflatoxins in the dairy production chain.