Background: Aflatoxin M₁ (AFM₁) as a carcinogenic and toxic compound has considerable significance from public health viewpoint. The aim of this study was to determine the level of AFM₁ in pasteurized and UHT milk in West-Azerbaijan province of Iran.

Methods: A total of 360 commercial milk samples including 220 pasteurized milk and 140 ultra-high-temperature (UHT) milk were purchased randomly from large supermarkets and retail shops in seven different cities of West-Azerbaijan province of Iran. Concentration of AFM₁ in the samples was investigated by enzyme-linked immunosorbent assay (ELISA) method. Statistical analyses were carried out using SPSS version 16.0.

Results: From total of 360 samples, 77.7% (n = 280) were contaminated to AFM₁ with a mean of 75.8 ± 9.2 ng/l.  Seventy percent (n=154) of pasteurized milk and 54.2% (n=76) of UHT milk, exceeded the limits recommended by European Commission (EC) regulations (50 ng/l). Besides, 2.27% of pasteurized milk (n=5) and 2.1% of UHT milk (n=3) exceeded the prescribed limit of institute of standards and industrial research of Iran (ISIRI) and US food and drug administration (FDA) regulations (500 ng/l). Mean content of AFM₁ in contaminated pasteurized and UHT milk samples were 76.2 ± 8.4 and 72.6 ± 7.2 ng/l, respectively with no significant difference (p>0.05).

Conclusion: We found high presence of AFM₁ in milk samples which may pose a serious health hazard to local people. Therefore, milk and dairy products should be monitored continuously for this issue. Also, it is necessary to educate dairy farmers about effective ways to reduce aflatoxin contamination.