The American Beverage Association (ABA) pledged to "use every means necessary" to make all soft drinks makers aware that two common ingredients can react together to form benzene in drinks.
The ABA has been forced to re-visit the issue after America's Food and Drug Administration (FDA) revealed to BeverageDaily.com two weeks ago that it had found some soft drinks containing benzene above the legal limit for drinking water.
Benzene is listed by health authorities as a known carcinogen.
The news indicates a communication breakdown. Both the US soft drinks association and FDA knew 15 years ago that two ingredients - sodium benzoate and ascorbic acid (vitamin C) - could react together to form benzene in drinks, according to an internal FDA memo dated January 1991.
"15 years ago it was under control, but this is a fast-growing industry. There are a lot of new companies, a lot of new brands and things have changed," said ABA spokesperson Kevin Keane.
"A number of brands may not be aware of this," he said, adding there was, in any case, little health risk involved.
The FDA was re-alerted to the benzene issue in recent weeks by independent laboratory tests in New York.
The lawyer who commissioned the tests also told the ABA some of the results before Christmas. The association said Thursday it was not testing drinks itself "at this point".
The New York lab found some soft drinks with benzene levels several times above the World Health Organisation's 10 parts per billion (ppb) limit for drinking water. The FDA water limit is half that, while safety bodies in the EU use a limit of just 1ppb.
Perrier sparkling water and Britvic drinks were recalled at lower benzene levels in the 1990s.
The industry, however, has repeatedly argued that such levels posed little health risk to consumers. The ABA said people could get more benzene from the air they breathed.
Michael Knowles, director of scientific and regulatory affairs at Coca-Cola Europe, said soft drinks makers had learnt to control benzene formation in drinks containing ascorbic acid and sodium benzoate. "We know how it is formed and we know how we can minimise the formation."
Knowles said soft drinks companies made a value judgement to use sodium benzoate because of its strong ability to kill off bacteria in drinks. He said the preservative's benefits outweighed the risks and consumers needed to understand this.
Debate, nevertheless, has begun to focus on the effect of heat and light on the amount of benzene that could form from a reaction between sodium benzoate and ascorbic acid.
"Heat is a major factor," according to Mike Redman, an ABA scientist who also represented the industry in meetings with the FDA on benzene back in 1990/1991.
He said benzene levels would not rise significantly at room temperature, but could rise under extreme conditions.
It is thought that Cadbury Schweppes exposes drinks to heat in an incubator for a set period of time to monitor formulations. The group was unable to confirm this before publication.
Cadbury, alongside Australian drinks group Koala Springs, originally alerted the industry and FDA to a problem with sodium benzoate and ascorbic acid back in 1990. It also then led industry testing for benzene, before it and others reformulated some of their drinks.
The ABA's Mike Redman said the industry would now re-trace its steps. "We will review the 1990 reformulations to see if there's anything we have learnt since that time."
He said benzene formation could be best controlled by adjusting levels of sodium benzoate and ascorbic acid in the drinks.
Diet and sugar-free drinks are considered more at risk because sugar has been found to help block the reaction.
Glen Lawrence, another scientist who helped the FDA work out the problem with ascorbic acid and sodium benzoate in 1990, took a firmer stance:
"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."
More than 1,500 soft drinks containing sodium benzoate and ascorbic acid or citric acid have been launched across Europe, North America and Latin America since January 2002.