New Delhi, Sept. 2: A government laboratory has detected cancer-causing fungal toxins exceeding safety limits in samples of ultra-high-temperature processed milk, suggesting that a contamination problem highlighted eight years ago remains unresolved.
Scientists at the Central Food Technological Research Institute (CFTRI), Mysore, have found a compound called aflatoxin M1, a fungal product labelled a carcinogen, in about 20 per cent of the samples of UHT milk they examined.
Earlier studies in India over the past decade have identified aflatoxins in raw and pasteurised milk but, the CFTRI scientists say, this is the first report of aflatoxins in UHT milk.
Dairy experts estimate that UHT milk — typically sold in tetrapacks as a shelf-stable product that needs no refrigeration until opened — makes up only one per cent of India’s milk market, but sales are expected to grow three-fold over the next five years.
Food safety specialist Prema Viswanath and her colleagues at the CFTRI selected 45 samples of UHT milk from retail stores in Mysore, but intentionally picked brands sold across the country. Their findings appeared last week in the journal Food and Chemical Toxicology.
The scientists found aflatoxin M1 levels exceeding limits imposed by India’s Food Safety and Standards Authority (FSSA) in 10 out of the 45 samples of UHT milk, in six out of 45 samples of raw milk and in three out of seven samples of pasteurised milk. The raw and pasteurised milk was collected from milk suppliers across Karnataka and Tamil Nadu.
High levels of aflatoxins in livestock feed — such as maize residue and peanut cake — appears to be the source of the toxins in milk, the CFTRI scientists said.
Toxicologists say the findings suggest that India’s livestock sector has failed to resolve the problem of aflatoxins in feed despite repeated warnings.
“This is a complex problem which is why it persists,” said Mukul Das, a biochemist and co-ordinator of food toxicology at the Indian Institute of Toxicology Research (IITR), Lucknow.
Das and his colleagues at the IITR had detected aflatoxin levels high enough to cause concern in samples of infant milk food, milk-based weaning cereals and liquid milk in 2004.
“It’s a quality issue involving the livestock and dairy supply chain,” Das said. Sections of the dairy industry that rely on milk supplies from livestock owners need to test samples for aflatoxin before they pool the milk for industry-level processing, he said.
“Clean livestock feed holds the key to clean milk,” said Viswanath. Studies from outside India have indicated that aflatoxins are resistant to heat treatment. “The objective should be to reduce aflatoxin levels to as low values as possible,” Viswanath told The Telegraph.
Indian livestock researchers have in the past reported high values — up to 3,300 micrograms per kg — of the fungal toxin aflatoxin B1 in livestock feed. Aflatoxin B1 is metabolised by animals and converted into aflatoxin M1, which is secreted in milk.
“We’re aware of the problem,” said Anil Kumar Srivastava, director of the National Dairy Research Institute, Karnal, Haryana. “Humidity, moisture, and poor storage conditions contribute to the growth of fungi and aflatoxins in livestock feed.”
Dairy researchers point out that aflatoxins have been detected in UHT milk in several countries, including Brazil, Iran, Kuwait, Spain and Turkey. But while most developed countries have set maximum permissible limits for aflatoxin levels in livestock feed, no such mandatory limits exist for livestock fodder in India.
Toxicologists view aflatoxins, produced by fungi called Aspergillus flavus and Aspergillus parasiticus as among the most potent of carcinogens that can cause liver cancer. Some studies indicate that aflatoxins can also lead to stunted growth.
Since the late 1990s, isolated scientific reports of aflatoxins in milk have emerged from Thrissur in Kerala and Anand in Gujarat.
The 2004 study by Das and his colleagues at the IITR had found about 10 per cent of samples of products they tested contained aflatoxin M1 levels higher than the 0.5 microgram per kg limit imposed by the FSSA in 2006.
The limit for aflatoxins in milk set by the European Commission is even lower — 0.05 microgram per kg. “If we apply the European Commission limits to our samples, 90 per cent would exceed safety limits,” said Das.
Both the CFTRI and the IITR are laboratories under the Council of Scientific and Industrial Research.