While soft drinks sold in the market have high levels of harmful chemicals -- like phosphoric acid, caffeine and ethylene glycol -- the law that must be used to regulate these remains underutilised, experts said on Thursday.

Phosphoric acid is added to give that 'zing' to the soft drink, but it increases the acidity of the drinks, said noted lawyer Prashant Bhushan at the 'South Asian Media Briefing Workshop on Food Safety and Pesticide Contamination' in New Delhi.

Some of these substances are added to lower its pH value and increase the life of the product. Low pH value (or high acidity) prolongs the shelf life of soft drinks, but high acidity affects the gastrointestinal tract and liver, he said.

• Soft drinks, hard truths

Sunita Narain from the Centre for Science and Environment said that Indian law allows up to 200mg/kg of caffeine in soft drinks and does not differentiate between different types of soft drinks.

Thus, companies are putting caffeine in non-cola drinks as well. For example, Mountian Dew, a new non-cola product launched by PepsiCo in India, had one of the highest caffeine content, even more than cola drinks, she said.

High intake of caffeine is known to cause insomnia,

nervousness, anxiety, fluctuating heart rate, osteoporosis and miscarriages, she said.

In other parts of the world, companies offer both caffeinated and non-caffeinated versions of soft drinks, she said.

Presence of ethylene glycol, which is a constituent of car coolants, in soft drinks is also a matter of concern, Bhushan said, adding it is known to be carcinogenic. Its presence allows cooling under very low temperatures without freezing of the drink.