NIN study reveals contamination in Hyderabad raw milk: food safety alert

A study by the ICMR-National Institute of Nutrition (NIN), Hyderabad, found faecal coliform bacteria in 90.5% of raw bovine milk samples collected from two city localities, with Salmonella detected in roughly one-third of those same samples.

The research, published in the UK journal Philosophical Transactions of the Royal Society, tested 42 milk samples, 20 water samples, and 24 cattle-feed samples drawn from Hyderabad's Addagutta and Warasiguda areas. NIN director Dr Bharati Kulkarni co-authored the study alongside researchers from the Royal Veterinary College, the International Livestock Research Institute, and the London School of Hygiene and Tropical Medicine. The findings were reported by the Times of India on 10 July 2026.

The contamination numbers are stark. Of the 42 milk samples:

• 90.5% contained faecal coliform bacteria
• 95.2% were positive for yeast and mould
• About 33% tested positive for Salmonella, a bacterium that causes severe food poisoning and intestinal infections
• Nearly 31% contained Staphylococcus aureus, which produces heat-stable toxins that survive even after cooking
• About 12% tested positive for E. coli, associated with diarrhoea and intestinal infections

The water used to clean milk cans and dairy equipment was equally compromised. Of 20 water samples, 95% showed bacterial growth, 70% contained faecal coliform bacteria, and 60% had yeast and mould. That means the cleaning step, which should reduce microbial load, may actually be recontaminating equipment before milk ever reaches the consumer.

What this means for Hyderabad's milk supply chain

Raw milk in India is not a niche product. Across cities including Hyderabad, a large share of households still receive milk directly from informal dairy vendors, bypassing the pasteurisation that commercial brands like Amul (Gujarat Cooperative Milk Marketing Federation) or Heritage Foods apply. FSSAI's Food Safety and Standards (Milk and Milk Products) Regulations, 2011, require that milk sold for direct consumption be pasteurised, but enforcement at the last-mile vendor level is inconsistent and the NIN study does not cite any recent FSSAI action specific to these localities.

Faecal coliform bacteria in milk is a standard indicator of poor sanitation at the farm or collection point. Its presence at 90.5% prevalence is not a marginal finding. Salmonella contamination at one-third of samples is particularly concerning because Salmonella typhi and non-typhoidal Salmonella strains are leading causes of hospitalisation from foodborne illness in India, according to the Indian Council of Medical Research's disease burden data. Staphylococcus aureus is a separate problem: its enterotoxins are heat-stable, so boiling milk at home does not neutralise them once they have formed.

The study also examined why contamination enters the chain in the first place. Researchers found that rising cattle-feed costs and veterinary expenses have placed many small dairy farmers under financial pressure. Some respondents alleged that milk is diluted with water at various points, and that substances such as urea and milk powder are added to restore the appearance of undiluted milk. The researchers were careful to note these claims came from interviews with people in the dairy trade and were not independently verified through laboratory testing. NIN scientist and co-author Naveen Kumar Ramachandrappa said some respondents may have confused normal processing with adulteration.

Farmers without access to cooperatives or producer associations face the sharpest squeeze. Without collective bargaining, they accept lower prices from large dairy companies, which the study says can push some toward cutting corners on hygiene or volume.

What buyers and home cooks should do

The NIN study covers raw milk only. Commercially packaged, pasteurised milk from licensed dairies is processed at temperatures (typically 72°C for 15 seconds under HTST pasteurisation) that destroy the pathogens found in this study, including Salmonella and E. coli. If you buy loose milk from a local vendor in Hyderabad or elsewhere, the contamination risk the study documents is real and not theoretical.

Boiling milk at home reduces but does not eliminate all risk. As noted above, Staphylococcus aureus toxins can survive boiling. The safest mitigation is to bring milk to a rolling boil immediately after purchase and consume it the same day, stored in a clean, covered container. Do not store raw milk in the same vessel used for transport without washing it first, given that the NIN data shows cleaning water itself is frequently contaminated.

For households with infants, young children, pregnant women, or immunocompromised members, Dr Kulkarni's warning in the study is direct: repeated consumption of contaminated milk increases the risk of diarrhoea and other infections in people whose immune systems are still developing or are otherwise weakened. For these groups, switching to commercially pasteurised milk from a licensed brand is the lower-risk choice.

For those who prefer raw or minimally processed dairy for dietary or Ayurvedic reasons, the study does not address whether any specific sourcing arrangements (such as direct farm purchase with verified hygiene practices) produce cleaner milk. That data does not yet exist in the public domain for Hyderabad. Until it does, the contamination rates documented by NIN apply to the informal supply chain as a whole.

The study does not name specific vendors, collection centres, or farms. FSSAI has not, as of the date of this article, announced any enforcement action or sampling drive in Addagutta or Warasiguda in response to the findings. Whether the publication in a peer-reviewed journal prompts a regulatory response from the Telangana Food Safety department or FSSAI's Hyderabad office remains to be seen.