Over 75% pasteurised milk unsafe for direct consumption in Bangladesh: icddr,b study

A new research has found more than 75 of all pasteurised milk marketed in Bangladesh unsafe for direct consumption.

Researchers at the icddr,b have revealed the disturbing findings about the commercially pasteurised milk, the primary source of nutrition for children in Bangladesh. 

The Dhaka-based diarrhoeal disease research centre says at every stage of the dairy value chain - from the farm to store - milk is found to be “highly contaminated with bacteria” above national and international standards.

However, this can only be dangerous if consumed raw or unboiled, which is often the case in Bangladesh, according to the researchers.

To assess the microbiological quality of milk at different stages of the dairy value chain, the researchers analysed 438 raw milk samples from milk producers, collectors, chilling plants, local restaurants in the northern part of the country and 95 samples from commercially processed milk found on the shelves of local retail stores in Dhaka and Bogura.

They found 72 percent samples from primary-level producers were contaminated with coliform and 52 percent with faecal coliform bacteria.

They also found 11 percent of these samples were contaminated with high amount of E coli.

The faecal coliform bacteria is considered as a hygiene indicator and its presence in the milk indicates that the milk has been contaminated with pathogens or disease-producing bacteria or viruses.

These can also exist in faeces of warm-blooded animals, meaning the role of milking animal or the farmers may also be blamed for this.

At the collection points, samples were found contaminated with a high number of coliform bacteria and faecal contamination of 91 percent while more than 40 percent of the samples had a high E coli count.

At the chilling plants, collected samples were found to be contaminated even at a higher rate than those of collection points.

Samples from all 15 chilling plants distributed in five districts were contaminated with high number of coliform as well as faecal coliform. E coli was found in samples from all chilling points while 67 percent of samples were contaminated with high level of E coli.

Bacterial counts in milk gradually increase from producers’ level to the chilling plants and to the consumers’ levels like local restaurants. 

Even more concerning is the fact that the scientists found about 77 percent of all pasteurised milk samples had a high level of total bacterial counts, which was beyond the Bangladesh Standards and Testing Institution or BSTI standards.

The researchers found 37 percent of the same samples contaminated with coliform and 15 percent with faecal coliform bacteria.

Pasteurisation is done to kill pathogenic bacteria to make the milk safe to consume. Both the national and international standards have zero tolerance for faecal coliforms in pasteurised milk.

Dr Mohammad Aminul Islam, who headed the study, warned consumers about the risks of consuming pasteurised milk unboiled. 

“Raw or pasteurised milk available in the market are found to be contaminated with disease-causing organisms and should not be consumed without thorough boiling,” the icddr,b quoted him as saying in a statement. 

The associate scientist and head of the Food Microbiology Laboratory at the icddr,b also said the samples pasteurised at ultra-high temperature or UHT were found to be safe for direct consumption.

He said they did not test the milk for chemical contamination or adulteration in the study.

“Our studies show that several factors are involved in the contamination of milk at the primary producers’ level including the breed of the cow, volume of milk produced by the cow, the time of milking, and farmers hand washing practices,” he said.

Dr Islam recommended end-to-end compliance of hygienic milking practices, collection and delivery, preservation and pasteurisation practices by Bangladesh’s dairy companies to ensure safe and nutritious milk for all.

“Maintenance of seamless cold chain throughout the distribution channel of pasteurized milk from factory to consumer’s table is also critical for ensuring safe milk for consumption,” he added.

The research was funded by CARE Bangladesh through its ‘Strengthening the Dairy Value Chain (SDVC)’ project and was conducted in 18 Upazilas of Bogura, Gaibandadha, Nilphamari, Dinajpur, Joypurhat, Rangpur and Sirajganj.

The findings have been published in the International Journal of Food Microbiology.