Levels of benzene found in soft drinks so far are not a safety risk for consumers, says the US food safety watchdog, attempting to calm public concern.
The US Food and Drug Administration (FDA) made the statement in a letter to the Environmental Working Group (EWG), a campaigns body.
The EWG had asked authorities to warn consumers, after the FDA revealed to BeverageDaily.com in February it had found some drinks containing benzene above the legal limit for drinking water in the US.
The FDA has tried to reassure consumers by emphasising there was no immediate risk to consumers' health from benzene levels found so far in drinks. Most drinks were well inside the limit for water, it said.
Still, the agency added it would not release results until it had done more testing.
Benzene is listed as a carcinogen by health authorities.
Both the FDA and America's soft drinks association have known for 15 years that benzene could form in soft drinks containing a combination of sodium benzoate and ascorbic acid (vitamin C).
No public announcement was made and the FDA agreed to let the soft drinks industry "get the word out and reformulate", found a BeverageDaily.com investigation earlier this year.
The US safety watchdog was re-alerted to benzene in soft drinks by private laboratory testing in New York last autumn, paid for by a US lawyer and an industry whistleblower.
The news indicated a communication breakdown. Both FDA chemist Greg Diachenko and American Beverage Association spokesperson Kevin Keane, subsequently told BeverageDaily.com it was possible that some firms had not got the message about sodium benzoate and ascorbic acid in drinks.
More than 1,500 soft drinks containing both sodium benzoate and ascorbic acid or citric acid have been launched across Europe, North America and Latin America since 2002.
The FDA said it was now working with the relevant companies to reduce benzene levels where necessary, in what appears a similar approach to that taken 15 years ago.
Industry testing back then showed that benzene levels could rise several times when drinks containing sodium benzoate and ascorbic acid were exposed to heat and light.
Adjusting the levels of sodium benzoate and ascorbic acid, as well as adding sugar and the additive EDTA, were found to help reduce benzene formation.
The renewed investigation has, however, sparked considerable debate over what level of benzene is acceptable in soft drinks.
There is no specific limit for soft drinks, and water limits range from 10 parts per billion (World Health Organisation), 5ppb in the US and one part per billion in the EU.
Glen Lawrence, a scientist who helped the FDA understand the problem with sodium benzoate and ascorbic acid in 1990, told BeverageDaily.com soft drinks companies should change their formulas.
"There is no good reason to add ascorbic acid (vitamin C) to soft drinks, and those that may have ascorbic acid naturally in them (juices) should not use sodium benzoate as a preservative. So it is really very easy to avoid the problem."
See the related news section (right) for BeverageDaily.com's breaking stories on benzene residues in soft drinks.