New Delhi: If you thought your glass of milk will give you guaranteed nutrition, think again!

The first mass survey of quality of milk supplied to consumers across the country by the Food Safety and Standards Authority of India has led to shocking discoveries with as many as 69 per cent of the samples failing the test of purity.

At least 14 per cent of milk samples were found to contain traces of detergents. However, these non-conforming milk samples were confined to states of Bihar, Jharkhand, Orissa and West Bengal only.

The survey by the country's food regulator to ascertain the quality of milk and find adulteration types, found that not a single sample of milk collected in seven states of Bihar, Chhattisgarh, Daman and Diu, Jharkhand, Orissa, West Bengal and Mizoram conformed to quality standards of milk.

Presence of sodium chloride was detected in a milk sample taken in Assam, while two samples taken in Nagaland saw presence of neutralizers.

However, all milk samples taken in Goa and Puducherry conformed to the standards.

The study indicates that addition of water to milk is the most common adulterant, which not only reduces the nutritional value of milk but contaminated water may also pose a health risk.

Any microbial contamination due to addition of contaminated water can, however, be overcome by thoroughly boiling the milk before consumption, the central food authority held.