The tobacco industry, not without at least some justification, long has resisted efforts aimed at getting cigarette producers to reveal their products’ ingredients. Cigarettes are, in fact, one of just a small handful of ingestible (for lack of a better word) products the packaging of which doesn’t reveal their ingredients. It takes a little poking around to find even the most basic information. (Gee whiz anyway, the warning label on my lighter is more verbose than that on a pack of my cigarettes.)

So what am I smoking? Benson & Hedges 100’s, the “full flavor” variety. Yeah, I know, I apparently fell for it, hook, line, and, uh, stinker. (Just kidding. I’ve tried dozens of brands and I keep coming back. It really is the taste. I swear. Hell, I take a lot of abuse for choosing this brand. “Old-lady cigarette,” my friends call it. Yeah, guys, your Marlboro Lights are so butch.)

What’s inside? Well, according to Philip Morris, there’s tobacco, of course, and all this:

Water
Sugars (Sucrose and/or Invert Sugar and/or High Fructose Corn Syrup)
Glycerol
Propylene Glycol
Cocoa and Cocoa Products
Licorice Extract
Diammonium Phosphate
Ammonium Hydroxide
Carob Bean and Extract
Natural and Artificial Flavors

Okay, so the cocoa, the licorice, and the carob bean I can deal with, but it’s been 20 years since I took a chemistry class and a couple of these items kind of worry me. (I almost majored in chemistry, believe it or not. Bet I’d have a job right now.)

Specifically, the propylene glycol (I remember enough chemistry, I think, to consider anything with “-lene” in its name a little scary), the diammonium phosphate, and the ammonium hydroxide. (Why does fertilizer come to mind with those last two?)

Any chemists out there want to help me out with this?

[Reader B.R. writes: “Propylene glycol is part of that greenish stuff you put in your car’s radiator. That’s right: anti-freeze. (See this site for more information.)” [Ed.: Wait, something goes in my car’s radiator? You mean, like, regularly? You mean, something that’s supposed to be refilled now and again? Huh. Good thing I don’t own a car anymore. Um, and to whoever bought my last car when I sold it, gee whiz, sorry about that. (Actually, I had it professionally serviced every three months. I assume they took care of that kind of thing.)] “Ammonium hydroxide: very bad stuff, especially when burned (this applies to many “non-toxic” substances). See this site for details. There are roughly 400 agents used in the processing of tobacco. Lots of them are KCCA (Known Cancer-Causing Agents). Then you burn `em.” [Ed.: Yeah, I know, but there’s also arsenic in oranges. And when did you ever see an ingredients label on an orange? (Of course, when did you last burn an orange?) So there. Sort of. Scare the bejeebus out of me, why dontcha? Not like I didn’t have it coming.]]

[Reader Jim McLaughlin, proprietor of A Skeptical Blog, writes: “Read your smoking post and thought I would help out. Let’s start with propylene glycol. This is from The Straight Dope: ‘Propylene glycol alginate is used as a thickener and stabilizer in such products as ice cream and candy as well as salad dressing. Originally derived from brown algae and since mixed with a few other goodies, the chemical has been used for almost a century in one form or another. It’s on the government’s GRAS (generally recognized as safe) list, but that just means it’s been around for a long time and hasn’t killed enough people to be conspicuous. As with many additives, little long-term testing has been done. PGA does not accumulate in the body, which is mildly reassuring, but there is some evidence that it inhibits the absorption of whatever nutrients happen to be in the food product it's mixed in with. On the positive side, it also inhibits the absorption of strontium, one of the more toxic components of nuclear fallout…something to keep in mind if you ever do menu planning the day after the Big One drops.’ Amusing no?” [Ed.: Mildly. But are we talking about the same propylene glycol? See addendum above.] “Here is the update on diammonium phosphate from the European Fertilizer Manufacturers Association:
‘Guidance For The Compilation of Safety Data Sheets For Fertilizer Materials
Diammonium Phosphate
1. IDENTIFICATION OF THE PRODUCT AND THE COMPANY
1.1 identification of the Product
Designation: EC Fertilizer, NP Fertilizer x : y
Trade name: N/A
Commonly used synonyms: Diammonium Phosphate, DAP Phosphoric Acid, Ammonium Salt 1.2
CAS Number: 7783-28-0
EINECS Number: 231-987-8
EINECS Name: Diammonium hydrogen ortho phosphate
Molecular formula: (NH4)2 HPO4’
Looks like you hit the nail on the head with the fertilizer comment. Last but not least, ammonium hydroxide. Now I have to admit, this one puzzled the hell out of me. I understand that the two mentioned above act as preservatives for the tobacco, but I have no idea why they would put ammonium hydroxide in a cigarette. For a clue just go and read this page: ‘Most common use is: Ammonium Hydroxide -- chemical formula NH4OH, ammonium hydroxide is a corrosive chemical with a strong ammonia odor. Ammonium hydroxide fumes are irritating to lungs, skin and eyes. Ammonium hydroxide is used in SC1 cleaning solutions and is commonly sold as a 30% solution with a density of 0.90Kg/L.’ Ugh. I guess I should thank you for this. It reminds me why I am in the process of quitting (one month, a lifetime to go). Enjoy your next smoke.” [Ed.: Thanks, Jim, I just did. Sort of, but not as much as usual.]]