Saturday, January 26, 2013

Some Thoughts on BVO Writeups

Hello there, 'science beat' journalists! I hear that Gatorade* just announced it would eliminate brominated vegetable oil (BVO) from its ingredients list (guess that chemophobic petition really worked, huh?)

Well, this is a chemistry blog, and I feel my skin crawl watching various scientific terms and concepts flying around sans context. So, let's set a few things right:

  • Bromide, bromine, and brominated all refer to elemental bromine, but they aren't interchangeable terms! Bromide refers to a single bromine atom with a full octet of electrons [reduced, or "Br(-)"], and is usually found in ionic salts (e.g. potassium or sodium bromide). Bromine refers to the element itself, a corrosive brown liquid. "Brominated" refers to a compound, usually carbon-based, that contains bromine atoms. Now you know.
  • Just because you cite the 2011 Scientific American article regarding BVO overexposure does not mean you've vetted the science! I've looked all over (WebMD, PubMed, SciFinder) for incidences of BVO poisoning, overdose, or excessive consumption, and I find...two. The 2003 NEJM (Ruby Red Squirt), and the 1997 J. Clin. Toxicol. (2-4 L of cola daily). Please don't say "a few" or "some" when you mean two.
  • Emulsifiers, such as BVO, don't "weigh down" or "sink" the citrus oil - they emulsify it! That means they help to disperse one liquid into another liquid, by promoting formation of tiny droplets of one inside the other. And it's not the use of "heavy" bromine atoms that does this, either. Even if it were, at 8 ppm (8 molecules BVO per ~1,000,000 of water), that's not a lot of mass! It's physics, folks. **Update (1/27/2013) -OK, you win this one, Internet! BVO really is a "weighting agent," and I won't harp on this point. Thanks, Prof. Kass. 
  • Chemophobia: Do we really have to have "chemical" in every lede? Much less reference the well-worn 'fire retardant' factoid? I'll tell you about another "fire-retardant chemical" widely found in soft's called water.
Hope this helps!

*A Pepsico brand, although some media relations person obviously told them to expunge all references to BVO or 'brominated' from their parent site...try the search box!

***Update (1/30/13) - CNN's coverage seems to have eschewed science to focus on PR reps and corporate statements: "...bromine is cited in some chemical company patents as a flame retardant." Sigh.


  1. It'd be cruel, but you could send the girl who started the petition an email saying that PepsiCo also hide a very common "fire-retardant chemical" called dihydrogen monoxide in drinks, hiding it under another name. Stick in a few links to the dihydrogen monoxide website, etc, and I'd love to see how far that petition went. You never know, someone might learn something.

  2. Good post, but BVO does "weigh down" the citrus oil, I think. That's it's point. Unlike most oils, BVO is denser than water, so mixing it with lighter citrus oil creates an oil blend that's the same density as water and that stays dispersed as a cloudy suspension. And while it's probably an oversimplification, it's sort of the case that the higher density of BVO as compared to non-brominated oil is due to the substitution of "heavy" bromine atoms for some of the oil's hydrogen.

    1. I certainly don't dispute that a brominated precursor will have a higher density than one that does not. But if the "weighing down" metaphor were correct, the entire phase would sink, correct? Instead, it emulsifies into the water. Do you believe that 8 ppm BVO is enough to create such a drastic shift in density?

      When emulsifiers are added to mayonnaise or other sauces, most wouldn't use the weight metaphor, but rather refer to it as "blending." It's more like a detergent than a "dense" additive.

  3. Sorry, but BVO is really a "weighting agent." That's not a metaphor. It's described that way in textbooks, and the function fits that description: You mix BVO with lower-density orange oil to create a flavored oil with the exact density of sweetened water so the final emulsion (Gatorade, Squirt, whatever) doesn't separate. In other words, BVO literally "weights down" the light citrus oil. Here are some references: and

    Why would the "entire phase", if by that you mean the orange oil + BVO mix, "sink" just because BVO is a weighting agent? Ballast is a weighting agent for boats, and boats don't sink. The weighted-down oil is designed to have exactly the same density of what its suspended in, so why would it sink? Of course, BVO alone (like ballast alone) would sink, if it weren't mixed with the citrus oil, just as citrus oil itself would float, if it weren't mixed with BVO to increase its density.

    Emulsification in mayonnaise is different. Mayonnaise is extremely viscous, so droplets of slightly different density won't float or sink. In a watery emulsion like Gatorade, however, the density of the droplets must match to avoid separation by sinking or floating. ("Orbitz" is an instructive example. While not really an emulsion, it is a product where droplets stay put because of both matched density and some viscosity in the surrounding liquid.)

    Whatever you contend, it's a fact that brominated vegetable oil has a higher density than unbrominated vegetable oil. Whether that's a general fact about brominated hydrocarbons or not, and whether or not that's due to the higher density of elemental bromine over hydrogen, I don't know, but I will note that Wikipedia mentions the fact that bromination of hydrocarbons tends to increase density: "Addition of covalently bonded bromine tends to increase the density and raise the melting point of organic compounds."

    Anyway, my point is that calling BVO a "weighting agent" is fine, and journalists shouldn't be criticized for doing that. (Calling it an emulsifier is also fine.) Most of your points here are good, and while the question of whether BVO can be called a weighting agent isn't a huge deal, it does deserve to be expressed clearly, and journalists shouldn't be criticized for something that isn't at all wrong.