A Review Finds Aflatoxin M1 in 58.7% of Bangladesh Milk Samples
A systematic review and meta-analysis examined 20 datasets from 12 reports published between January 2000 and January 2026. Across 605 milk samples, the pooled prevalence of aflatoxin M1 (AFM1) was 58.7%, with a 95% confidence interval of 51.6% to 65.5%. The prediction interval, reflecting variation among locations and surveys, ranged from 32.1% to 81.1%. The study was published in Veterinary Medicine and Science in 2026.
Levels varied against regulatory benchmarks. About 83% of the pooled samples contained more than 50 nanograms per litre, the European Union’s maximum level. A further 8% exceeded 500 nanograms per litre, the Codex Alimentarius value used in Bangladeshi standards. The sample-weighted arithmetic mean was 143 nanograms per litre, while the geometric mean was 92 nanograms per litre. One dataset from Dhaka recorded a mean concentration of 699.1 nanograms per litre; excluding it lowered the weighted mean to 93 nanograms per litre.
AFM1 is formed after dairy animals consume feed containing aflatoxin B1 (AFB1). The animal’s liver converts part of AFB1 into AFM1, which is then released into milk. The compound can remain present after pasteurisation and ultra-high-temperature treatment. The review noted that Bangladesh’s tropical monsoon conditions can support fungal growth during crop production, harvesting and storage, while maize, a major energy source in compound feed, is particularly susceptible to aflatoxin-producing fungi.
The studies included in the review reported AFB1 concentrations of 1–103 micrograms per kilogram in maize and 0–160 micrograms per kilogram in poultry feed. Contamination was also reported in oil cakes, bran, rice straw and soybean meal. Concentrations measured in cattle feed exceeded the European Union’s 5 micrograms-per-kilogram limit for dairy-cattle feed in the studies discussed, although many reported averages were below the general 20 micrograms-per-kilogram feed limit used for comparison.
Prevalence differed among regions and milk categories. The pooled estimate was 43.7% in Chattogram, 55.3% in Dhaka and 66.8% in other divisions and national samples. Regional differences remained statistically significant after adjustment, but the researchers described the result as exploratory rather than evidence of a confirmed geographical pattern. Estimates were 60.4% for raw milk, 59.0% for pasteurised milk and 69.5% for ultra-high-temperature milk. The differences by milk type were not statistically significant, and the ultra-high-temperature estimate was based on only two datasets.
The researchers also assessed dietary exposure using published milk-consumption and body-weight estimates. In the central scenario, exposure was estimated at 4.22 nanograms per kilogram of body weight per day for infants aged 6–12 months and 2.29 nanograms for children aged 1–3 years. Estimated margins of exposure for every age group were below the 10,000 benchmark used for potential concern involving genotoxic carcinogens. The authors identified infants and young children as priority groups for further investigation, while noting that the calculations were screening estimates rather than individual exposure measurements or forecasts of particular illnesses. The assessment covered milk and did not quantify exposure from other foods.
All milk measurements in the review used enzyme-linked immunosorbent assay, or ELISA, without chromatographic confirmation. Many studies relied on convenience samples rather than nationally representative sampling, and paired feed and milk samples from the same herds were not available. The authors recommended sampling feed and milk on the same farms during both monsoon and dry seasons, confirming results with more specific analytical methods and examining the unusually high Dhaka measurements. They also identified routine testing of feed ingredients and raw milk, improved storage and monitoring during milk collection and processing as areas for dairy-sector and food-safety authorities to address.
