You are not a cell in a test tube

This recent scare in the news is one of hundreds on my stack to talk about, but a surprisingly common sense, snarky little article appeared this morning urging a healthy dose of skepticism. It makes a fun way to segue into the science. He is talking about the recent story reported by the BBC, and repeated throughout the media, telling consumers that “worrying levels of the cancer-causing chemical benzene” had been found in soft-drinks.

The Independent’s version was especially scary-sounding, telling readers:

Research from a British university suggests a common preservative found in drinks [and used for decades] ... has the ability to switch off vital parts of DNA. The problem - more usually associated with ageing and alcohol abuse - can eventually lead to cirrhosis of the liver and degenerative diseases such as Parkinson's. The findings could have serious consequences for the hundreds of millions of people worldwide who consume fizzy drinks. They will also intensify the controversy about food additives, which have been linked to hyperactivity in children....

Professor Peter Piper, a professor of molecular biology and biotechnology, tested the impact of sodium benzoate on living yeast cells in his laboratory. What he found alarmed him: the benzoate was damaging an important area of DNA in the “power station" of cells known as the mitochondria.

This scare is nothing new and, like all such scares built upon urban legend with a portion of fear and misunderstanding of chemicals, has been recycled for years. And debunked. To get our critical thinking juices warmed up, we’ll start with a dose of humor:

The Healthy Skeptic: Warning, Diet Soda May Seriously Harm the Health of Yeast

... Did I mention that Peter Piper picked a peck of living yeast cells in order to study the affects of sodium benzoate delivered diet soda? Not anything that crawls or walks on two legs, or even four legs, but yeast cells. Not a mouse or mice, not a rat or rats and not humans. Peter Piper chose to study the effects of a preservative on yeast.... You would think that if Piper was really interested in seeing if diet soda was potentially dangerous to humans – rather than winding up with a certain outcome – he would have at least used a species that has a little more in common with humans....

This diet soda story stinks of agenda, and hasn’t a whiff of legit, objective science. Here are some of the main problems with this study and this story. As I mentioned, we’re given no indication as to why yeast was used to study the affects of sodium benzoate. For all we know, sodium benzoate could be the natural enemy of yeast cells. In the same way that humans cannot drink seawater and that flowers and fish cannot survive by being submerged in milk, perhaps yeast cannot tolerate sodium benzoate.

In the reporting of this study we aren’t given any details as to the concentration of sodium benzoate that the yeast cells were exposed to. Was the yeast “fed” 100% sodium benzoate or was the SB delivered in the same percentage that humans are exposed to? Was the yeast deprived of all other forms of “nutrition” or was this preservative delivered in a real-world fashion? I’m not aware of any food that contains 100% sodium benzoate, and I haven’t heard of an all sodium benzoate diet....

His first point is to remind us that a study in the laboratory does not mean it applies to real life on humans. But you’ll burst out laughing when you learn the answer to his question about why the professor spreading this fear might have chosen to use yeast cells for his test. The author wondered if sodium benzoate might be a natural enemy.

Yes, indeed. That is precisely why it is used in food products! To help keep foods and drinks safe to consume, according to the FDA, sodium benzoate or potassium benzoate is added specifically to prevent the growth of bacteria, yeasts, and molds. So, the fact this researcher showed that it worked against yeasts is nothing new to food scientists, nor means anything at all to people. It would appear this is little more than a publicity stunt to spook consumers away from “bad” foods and drinks, and reporters fell for it.

The healthy skeptic then wondered about the dose, noting that there’s no such thing as any food that’s loaded with sodium benzoate or benzene. His suspicions were right on target.

To get a grip here, we first have to put today’s exposures into perspective. Benzene is one of many compounds that are formed when organic matter decomposes or burns, as in forest fires and volcanoes. So, while it’s found in petroleum products and emitted when we pump gasoline into our cars and from its exhaust, it’s also emitted from burning wood, coal and oil — exposures that humans through much of history have had in more concentrated amounts and in close quarters. But most of us don’t heat our homes and cook exclusively with wood-burning hearths or use coal-burning furnaces; and light bulbs have replaced the gaslights and oil lamps of yesteryears. Vapor recapture devices on gas pumps and catalytic converters in our engines have also greatly reduced exposures there, according to the Agency for Toxic Substances and Disease Registry at the CDC. Our air exposures to benzene are considerably less today and, thankfully, few of us have walls in our homes covered in black soot anymore to show for it.

Still, benzene is ubiquitous in our environment and traces of it are everywhere. It’s proven useful in making all sorts of things that have made modern life better (nylon, lubricants, adhesives, detergents, rubbers, and polystyrene). The concern over its carcinogenicity and neurotoxicity originated with workers exposed to heavy concentrations in the air they breathed over many years, but safety precautions are in place today to minimize exposures in industrial settings. Also, to reassure pregnant women, “benzene has not been shown to be teratogenic in humans,” according to the Agency for Toxic Substances and Disease Registry.

Dr. Joe Schwarcz, director of the McGill University Office for Science and Society, adds:

When workers are exposed to less than 0.1 parts per million (ppm) of benzene in the air, there is no evidence of increased risk of leukemia. Since we know the average human inhales about 20 cubic meters of air a day, this translates to an exposure to 6 milligrams a day. Animal feeding studies have confirmed that at such doses there is no increased cancer risk.

Benzene is also found naturally in fruits and vegetables and is also part of nature’s fermentation process, so not surprisingly, it’s also been found in every food that the FDA has tested — except for American cheese and vanilla ice cream! It’s common in blueberries and cranberries; bananas can have 20 micrograms, hamburger 4 micrograms, etc. But in sodas, we’re getting down to parts per billion in nanograms. The EPA uses 5 ppb for water treatment plants, not because higher levels are known to be a health risk, but as a quality standard. But with everything together, according to Dr. Schwarcz, we get on average about 5 micorgrams in our diet and our diet is a comparatively minor source of exposure.

It’s been known for many years that benzene can naturally form in small amounts when sodium benzoate reacts with vitamin C — its presence in some soft drinks and fruit drinks is not because of contamination or something sinister. But to reassure the public, the beverage industry has been working with the FDA to keep levels as low as possible. Based on recent analyses conducted by the FDA’s Center for Food Safety and Applied Nutrition, most beverages contained either no detectable levels or levels below the 5 ppb limit for drinking water, and don’t suggest a safety concern, said Judith Kidwell, a consumer safety officer in the CFSAN’s Office of Food Additive Safety.

So, unless we want to stop enjoying cranberry juice or eating anything but processed cheese and ice cream, it makes no sense to worry about the latest soda scare, either. :)