Germany's food watchdog, BfR, confirmed it was examining soft drinks containing the common ingredients ascorbic acid (vitamin C) and sodium benzoate (E211).
The UK's Food Standards Agency has followed suit, saying it was looking into the issue and would sort out any problem found. An FSA spokesperson said the body was not aware the two ingredients could react together to form benzene, a known carcinogen.
Both authorities moved quickly after the US Food and Drug Administration revealed to BeverageDaily.com it had re-opened an investigation, closed for 15 years, into benzene in soft drinks.
The issue has never been announced to the public, with America's soft drinks association telling the FDA in early 1991 that it would "get the word out" across the industry about the need to reformulate drinks. More FDA tests in 1993 found no problem.
Yet, recent FDA tests showed some drinks in the US still contained benzene above the country's legal limit for drinking water, and an FDA chemist said more reformulation would be required.
The FDA was re-alerted to the issue by independent laboratory tests in New York.
The same lab also found a drink sold in Latin America by a well-known, international soft drinks group that contained benzene at more than six times the 10 parts per billion legal limit for water set by the World Health Organisation.
Soft drinks containing less benzene were recalled across Europe and US in the 1990s.
The New York lab, meanwhile, found two well-known drinks brands available in the UK with benzene at least three times above the country's strict one part per billion limit for drinking water. There is no specific limit for soft drinks.
Soft drinks sold outside the US are considered more at risk due to scant knowledge of the problem.
FDA testing in 1990 confirmed that ascorbic acid and sodium benzoate together in a soft drink could lead to benzene formation through the degradation of the benzoate.
And private industry tests revealed that the problem could get worse in a drink exposed to heat and light.
Yet, sources from food safety authorities in Belgium, Denmark and the UK have said they were unaware of the possibility that benzene could form in soft drinks containing both sodium benzoate and ascorbic acid.
Food safety bodies may have little reason to suspect a problem if they had not seen a 1993 article about it in the Journal of Agricultural and Food Chemistry, according to FDA chemist Greg Diachenko, who also helped co-ordinate FDA negotiations with the industry back in 1990/91.
Another problem is that relatively new or niche soft drinks makers left outside of the loop in the early 1990s may not know about potential 'fixes', he added.
"It is probable and likely that there were some people who did not get the message or that it was lost in the course of time."
More than 1,000 soft drinks containing both sodium benzoate and ascorbic acid or citric acid have been launched across Europe and Latin America since January 2002.
Spokespersons for soft drinks companies have insisted levels of benzene that may form in drinks from a deterioration of sodium benzoate were in no way a health risk to consumers.
The UK's Commercial Court agreed in a 2002 decision, yet warned: "The public perception will be that the carcinogen simply ought not to be present at all and that the manufacturers ought not to attempt to sell products which have been in that way inadvertently contaminated."
The court also concluded that "from time to time, relatively high yet not injurious levels of benzene seem to appear in uncarbonated drinks, which on the evidence can only be accounted for by the use of benzoate preservative".
It heard evidence that three parts per billion of benzene was "typically introduced" into drinks by use of sodium benzoate.
The public perception of this has, however, never been tested.