Friday, March 15, 2013

Please Set Me Straight on Synthetic Yellow Dyes

Dear Ms. Hari and Ms. Leake,

Good evening. Earlier tonight, I read your petition calling for a ban on Yellow #5 (tartrazine) and Yellow #6 (Sunset Yellow) in Kraft Mac & Cheese. I must say that, while not a mac connoisseur myself, I have certainly eaten it once or twice. Furthermore, I agree that all processed food companies should periodically review their popular brands, taking into consideration consumer sentiment, and should make every effort to produce quality goods. 

Since your petition now has well over 230,000 signatories, I assume many in the general public agree with us. But I must know: Where did you source the scientific data for your claims?

Let's start from the top:

"Artificial food dyes...are man-made in a lab with chemicals derived from petroleum (a crude oil product, which also happens to be used in gasoline, diesel fuel, asphalt, and tar)."
Well, I can't disagree with the first part - they're certainly synthetic azo dyes. However, I'd like to discuss your second point, where you equate 'petroleum-derived' to well-known flammable, smelly, or oozy black 'chemicals.' These azo dyes don't really resemble the compounds you've mentioned at all - gasoline and diesel are long saturated chains of carbon atoms, while tar / asphalt are collections of polycyclic aromatic hydrocarbons (PAHs), which might resemble these dyes if you took just the naphthalene portion (right-hand side), deleted the "OH" group, and chained a whole bunch of 'em together.
Yes, azo dyes come from organic chemists (like me!) in a lab somewhere. But, you know what else comes from petroleum? Pharmaceuticals. Plastics. Cosmetics. Synthetic fibers. Coatings. Many of the modern materials you interact with on a daily basis.
"Require a warning label in other countries outside the US."
I believe the US also mandates (Code of Federal Regulations Title 21, section 74.1705) inclusion of tartrazine on labels - I've seen it listed on my mouthwash. (Incidentally, that same CFR page sets exacting limits on impurity content in these dyes)
"Have been banned in countries like Norway and Austria (and are being phased out in the UK)."
Are we just lifting directly from Wikipedia by this point? 
"Yellow 5 and Yellow 6 are contaminated with known carcinogens (a.k.a. an agent directly involved in causing cancer)."
Now here's where things get interesting. Head on over to TOXNET, the National Library of Medicine toxicology database. I've looked up both Yellow 5 (tartrazine) and Yellow 6 (Sunset Yellow), and I can't find any positive studies suggesting carcinogenicity. Ditto both Wikipedia pages, and even my copy of the Merck Index (13th Ed., pp. 9091 and 9157).
What about the potential impurities, you ask? Sunset Yellow can indeed be contaminated with Sudan I (see picture, above), a non-sulfonated version of the compound. Sudan I lists as a Class 3 Carcinogen, which (thanks, ACS!) means "unclassifiable as to carcinogenicity in humans." The European Food Safety Authority (EFSA) actually re-evaluated Yellow 6 in 2009, declaring an acceptable daily intake and noting Sudan I contamination was well below the allowed limit for lead in processed foods.
I won't argue against your claims regarding hyperactivity and allergic reactions; the Hazardous Substances Databank (linked through TOXNET) indicates several studies in which patients do indeed respond poorly to artificial dyes. However, I will note that the responsive patient percentages are often low, and many weren't deemed statistically significant relevant to placebo.
I don't disagree with consumers' rights to petition companies for product changes. But please, check the science, lest you lapse into harmful chemophobia.
See Arr Oh

Update (8:00AM 3/15) - @thefoodbabe contacted me on Twitter with the following: "you are incorrect in your critique of our petition, I've got to go interview live with CNN now - Ciao"

Update 2 (9:00PM 3/15) - CNN posted two responses to the petition.
One leans scientific, the other mostly re-states the bloggers' objectives.


  1. It seems like the babe was just doing it for CNN.

  2. What a pompous response. It is doubtufl that she could even understand what is wrong with her petition. Some people have no idea how to handle media attention.

  3. Geez, its also *doubtful that I can spell.

  4. This is little more than slander against Chemists. Can we sue?

  5. Here's an interesting tidbit (It's a bit drawn out, but bear with me):

    One of the sources they cite is from "The Center for Science in the Public Interest" (Read: the Center for Raging Chemophobia). The article is here:

    This article has a pretty little infographic comparing the dyes used in Fig Newtons here and across the pond. In the UK, rather than using Red #40, they use Paprika Extract.

    And how is Paprika Extract extracted, you may ask? HEXANES (GASP!).

    So, by the logic of the chemophobes, UK Fig Newtons are made from gasoline!

  6. Drat, how did I forget you could win an argument with "You're wrong because I say so, and I'm a big shot now I'm on TV". I'm all for sensible, constructive debate on health issues, but I wonder how much evidence you'd actually have to present the petitioners with before they'd reconsider their point of view.

  7. Nice response, but I think your chemical structures produced information overload in her. Also as a matter of effectively getting your point across, I think you should have led with the fact that most drugs are synthetic (and listed a few examples) and are derived from "petroleum".

  8. haha "im right you're wrong. BRB on TV nyah nyah"

    is that her doing a backbend in a yellow bikini on her twitter page? why is this being taken seriously?

    anyway, i can understand a health nut picking on kraft mac and cheese but not for using synthetic dye

  9. I assume you're correct in your deconstruction of the petition's supposed scientific data. BUT, I think you missed the overall point of the petition. That artificial colors serve no useful purpose in food, and if they're not being used in Kraft's recipes for Europe, then why use them here? The petition makes a valid point in this respect. So, while I can respect your corrections of the data in the petition, I also respect the people who started the petition, because the motive was good. Don't we all want to be paying attention to what goes into our bodies and the bodies of our children? Macaroni and cheese may not be the healthiest food in the world, but it certainly can be made without chemicals. Why add them if they're not necessary?

    1. Just to be clear, macaroni and cheese, or any food for that matter, CANNOT be made without chemicals.