Worrying levels of the cancer-causing chemical benzene have been found in four soft-drinks available in the UK, the Food Standards Agency says.
Benzene levels are limited to one part per billion UK water ( pic by freefoto.com)
Benzene was undetectable in most of the 150 drinks tested.
Two companies have already withdrawn their drinks from shops and the FSA says the other two should follow suit.
The FSA urged drinks companies should reduce benzene levels - but says consumers should not be worried if they have drunk the affected products.
In the UK, drinking water should have a benzene level of no more than one part per billion.
The World Health Organization's health limit is set at 10ppb.
The FSA based its recommendations for the removal on drinks on the WHO levels.
Its tests were carried out after a BBC investigation revealed industry data showed benzene levels at up to eight times recommended UK levels.
In the tests, a batch of the Co-op's low-calorie bitter lemon drink with a best before date of June 2006, had the highest benzene level of 28 ppb.
A second batch of the same drink, with an 10 August best-before date had 11ppb.
The Co-op has already removed the affected batches from its shelves.
Morrisons' no-added sugar pineapple and grapefruit crush, with a best before July this year, which had 11 ppb, is also being removed from sale, the company has announced.
The other drinks with above WHO levels were:
- Popstar's still sugar-free lemon and lime drink - best before 22 April - 17 ppb
- Hyberry's no-added sugar blackcurrant squash - best before September - 12 ppb
In 107 out of 150 of the samples tested the levels of benzene were undetectable.
Thirty-eight samples had levels of benzene between one and 10 ppb.
Benzene, which can cause certain cancers, is thought to be formed when two commonly used soft-drink ingredients - the preservative sodium benzoate and ascorbic acid - interact.
People who have inhaled very high levels of benzene in the work place have been found to Increase their risk of cancer.
But the FSA says people would need to drink more than 20 litres of a drink containing benzene at 10 ppb to equal the amount of benzene you would breathe from city air in a day.
Dr Andrew Wadge, Director of Food Safety at the FSA said: "We did this survey to get a clearer picture of whether benzene was present in any soft drinks on sale in the UK and at what levels.
"We found that levels in the vast majority of products tested were low and not a cause for concern.
"However we are concerned about the levels in four drinks and have asked their manufacturers to remove the affected batches from sale."
He added: "These results show that it is technologically possible to produce soft drinks without detectable traces of benzene. This is what we want all manufacturers to do."
But Dr Wadge stressed: "Whilst it is important that industry take action, people should not be alarmed if they have drunk these products.
"The levels of benzene reported in this survey will only make a negligible impact on people's overall exposure to benzene and so any additional risk to health is therefore likely to be minimal."