Tests conducted on 230 drinks on sale in Britain and France have identified high levels of benzene, a compound known to cause cancer, according to the Food Standards Agency. There is a legal limit of one part per billion of benzene in British drinking water. The latest tests revealed levels of up to eight parts per billion in some soft drinks.

Benzene has been linked to leukaemia and other cancers of the blood. Traces found in Perrier water 15 years ago led to the withdrawal of more than 160 million bottles worldwide. The disclosure has prompted food safety campaigners to demand that the Government reveal which products contain benzene. At present, the drinks’ identities have not been revealed.

Richard Watts, of Sustain, a pressure group lobbying for better food standards, said that this should be done urgently because the drinks were being marketed to children. “The scientific evidence is unclear about whether there is any safe level of benzene. We see no reason why it should be different from the designated safe level in drinking water. If it is unsafe in drinking water, why should it be safe in soft drinks?” he said.

The Food Standards Agency, the government watchdog, said that the products did not pose an immediate health risk, but called for further investigation from the British drinks industry. “Let’s have further investigations and regular discussions with the drinks industry to check what is happening. If levels are high then the FSA will take action to protect consumers,” an agency spokesman said.

Food scientists believe that high levels of benzene may have been produced by the reaction of two commonly used ingredients — sodium benzoate, a preservative, and ascorbic acid (vitamin C). Sodium benzoate is widely used in the drinks sector. In Britain, it is used in Britvic brands including Britvic 55 apple and orange flavours, Pennine Spring flavoured waters and Shandy Bass.It is not known if any of these products were included in the latest tests. A spokesman for Britvic has previously expressed confidence in its products.

A spokesman for the British Soft Drinks Association said yesterday that the industry was working to reduce the levels of benzene in soft drinks. “There is an obligation on the industry to have as low a level of benzene as possible and we are looking at ways of reducing the levels — and maybe even removing the preservative — if we can replace it with something else,” he said.

When minuscule traces of benzene were discovered in Perrier water 15 years ago, it forced the French company to withdraw millions of bottles.

Tests have been carried out in Europe after US food watchdogs found benzene in juices and sodas. The Food and Drug Administration registered its concern about the possible long-term effects on health.

Professor Glenn Lawrence, of Long Island University, who first conducted tests for benzene in soft drinks 13 years ago, said that the combination of sodium benzoate and vitamin C was commonly used in drinks in the early 1990s.

He said that drinks firms were now putting vitamin C back into drinks to encourage consumers to buy the product. He said that this was being done to encourage parents to buy the drinks to improve their children’s health but it might just be doing the opposite.

BENZENE FACTS

Michael Faraday discovered benzene in 1825 when he isolated it from oil gas to form a chemical, six parts carbon, six parts hydrogen

It is produced during incomplete combustion of carbon-rich substances: it is produced from petrochemicals, but occurs naturally in volcanoes, forest fires and in cigarette smoke

In the 19th and early 20th centuries it was used in aftershave, for its pleasant smell, and to decaffinate coffee. It is now used as an anti-knock agent in petrol

It is an aggressive carcinogen and may lead to leukaemia and other cancers of the blood

In 1993, Professor Glenn Lawrence, of Long Island University, published research showing that the sodium benzoate and vitamin C found in soft drinks could react to form benzene. He suggested that drink companies were putting vitamin C into drinks to encourage customers to buy them