The Presence of Aflatoxin M1 in Milk and Milk Products in Bangladesh

As milk provides both micro- and macronutrients, it is an important component in the diet. However, the presence of aflatoxin B₁ (AFB₁) in the feed of dairy cattle results in contamination of milk and dairy products with aflatoxin M₁ (AFM₁), a toxic metabolite of the carcinogenic mycotoxin. With the aim to determine AFM₁ concentrations in milk and milk products consumed in Bangladesh, in total, 145 samples were collected in four divisional regions (Sylhet, Dhaka, Chittagong, and Rajshahi). The samples comprised these categories: raw milk (n = 105), pasteurized milk (n = 15), ultra-high temperature (UHT)-treated milk (n = 15), fermented milk products such as yogurt (n = 5), and milk powder (n = 5). AFM₁ levels in these samples were determined through competitive enzyme-linked immunosorbent assay (ELISA). Overall, AFM₁ was present in 78.6% of milk and milk products in the range of 5.0 to 198.7 ng/L. AFM₁ was detected in 71.4% of raw milk (mean 41.1, range 5.0–198.7 ng/L), and in all pasteurized milk (mean 106, range 17.2–187.7 ng/L) and UHT milk (mean 73, range 12.2–146.9 ng/L) samples. Lower AFM₁ levels were found in yogurt (mean 16.9, range 8.3–41.1 ng/L) and milk powder samples (mean 6.6, range 5.9–7.0 ng/L). About one-third of the raw, pasteurized, and UHT milk samples exceeded the EU regulatory limit (50 ng/L) for AFM₁ in milk, while AFM₁ levels in yogurt and milk powder samples were well below this limit. Regarding regions, lower AFM₁ contamination was observed in Chittagong (mean 6.6, max 10.6 ng/L), compared to Sylhet (mean 53.7, max 198.7 ng/L), Dhaka (mean 37.8, max 97.2 ng/L), and Rajshahi (mean 34.8, max 131.4 ng/L). Yet, no significant difference was observed in AFM₁ levels between summer and winter season. In conclusion, the observed frequency and levels of aflatoxin contamination raise concern and must encourage further monitoring of AFM₁ in milk and milk products in Bangladesh.