May 4, 2006
Benzene Soft Drinks Redux
One further thought on the benzene soft drinks story following on from sciencebase reader Ross Getman’s comment…
Bob Buntrock (of Louisiana State University) on the CHMINF-L discussion group mentions the recent C+EN article on this issue, (Dispute Over Benzene In Drinks, Bette Hileman, Chemical and Engineering News, 84(17), April 24, 2006).
Buntrock points out that when tests were carried out again in 2005, they revealed a very different picture of benzene levels than before. Apparently, previous tests by the FDA showed that almost four out of five beverages tested, even after “reformulation”, had benzene levels greater than 5 ppb, the US standard for tap water. The latest (preliminary) tests showed no benzene or levels less than 5 ppb.
“Since the first method involved heating samples at 100 Celsius for 30 minutes(!) [His exclamation] and the latest method uses headspace methodology “which does not involve much heat”, guess which method would appear to be more accurate,” says Buntrock. In his opinion, “considerably more decarboxylation of many acids or carboxylates will occur under the previous drastic conditions, which are extremely unlikely to occur under normal usage of soft drinks.”
Jacob Zabicky of Ben Gurion University, Israel, followed up Buntrock’s comment with a remark based on knowledge of the physical properties of benzene. “My gut feeling based on the relative solubility of benzene in water and its volatility from solution at ppb levels,” he said, “is that if there is any ppb level benzene at the start it will go with the fizz.” On the basis of the Henry Constant of benzene in water, Zabicky adds that, “The given value means that for every four molecules dissolved in a given volume of water one molecule of benzene is found in the same volume of headspace in equilibrium.” In other words if the headspace volume is large (i.e. the air above a drinks can as it is opened) compared to the volume of soft drink, then the benzene will be strongly depleted from it.
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Ross Getman said,
May 8, 2006 at 12:57 am
I take issue only with the statement of fact that “The latest (preliminary) tests showed no benzene or levels less than 5 ppb.” To the contrary, scientist George Pauli confirmed to reporter Chris Mercer that a small number had been two and four times the EPA limit. Without turning to the cited article, the only party I’ve ever known to get the fact wrong was ACHS, an industry group (and that was just a matter of reading comprehension as the nutritionist was just commenting on Mercer’s report. Over 200 tests have been done here at an independent, certified lab. At the time FDA was sharing, they had done 30 and according to reporters they were saying that a small number had tested two and four times the EPA limit. Bellywashers and Talking Rain are two examples of products that consistently score far above WHO levels over a range of flavors. But there are Coca-Cola, Pepsi and Kraft products that test over the WHO limits and the scientists can put their methodology to the test in open court (if there is any disagreement). The fact that the FDA may not have known what it was doing at any particular time is of little moment.
Shelf life can make a BIG difference.
sciencebase said,
May 8, 2006 at 8:41 am
I stand corrected.