Superhero potion

October 5, 2007 8:44 PM

Heavy water applied to skin- a bad idea? If so, why?

I've seen a number of cosmetic companies marketing a heavy water face mist. The wikipedia article on heavy water says that it slows down cellular regeneration; the cosmetics companies all say (and I do mean all, since all cut and paste this exact bit): D2O is Deuterium Oxide - heavy water. Its hydrogen molecule is twice the weight of the molecule in ordinary water, which makes D2O 10% heavier than H2O. Research has found that:

" * Heavy Water has a higher resistance to vaporization, which helps it stay on the skin for longer periods of time.
* It has more viscosity. This "thickness" gives it a higher "plumping" effect than regular water and the skin does not dry out as quickly or as deeply.
* It requires ten times as much energy to be ionized than regular water, which makes it more protective against ultra violet radiation.
* It inactivates certain acne bacteria, making it an ideal moisturizing agent for blemish-prone skin."

I haven't been able to come up with anything that specifically applies to skin, other than some research about frog skin permeability. It seems to me that something that slows down normal cellular processes is a sketchy thing to apply to your face every day. I just can't find good info, pro or con.

posted by oneirodynia to health & fitness (14 comments total)

Seems sketchy. The "effects on humans" section says it would be really hard to kill someone with it though, so maybe it's not that dangerous. That said, why would you want to slow or stop cell division? Your skin needs to be replaced as old layers die, no?
posted by phrontist at 8:50 PM on October 5, 2007

Heavy water (pure heavy water) has been shown to stop cell division. Note, however, that since your body is mostly light water, and your cells are light water, I don't see how a bit of heavy water sprinkled on the skin would make much difference.

The difference in vaporization is only very slight as far as I can tell from the numbers, although I may be interpreting them wrong. If is true, I doubt the other effects would be important at all. Want to be protected from UV rays? Think of how quickly water you put on your face evaporates out in the sun. Heavy water would evaporate in only a very, very slightly longer amount of time. How the hell is it supposed to protect you from UV radiation better than old-fashioned unscreen?

I'm hoping someone else with better knowledge will come along to provide a better answer, but I feel the cosmetic use of heavy water may fall into the category of "Hey, SCIENCE has found all these amazing things about heavy water...SCIENE, I tell you! How about you pay us $30 for a bottle and spray it on your face, it's sure to do some good."
posted by Jimbob at 8:58 PM on October 5, 2007

Here's the Material Safety Data Sheet for Deuterium Oxide:

Toxicology: Not hazardous according to Directive 67/548/EEC. High concentrations in the body can affect biochemical processes. Ingestion of large amounts impairs kidney function, CNS operation.

Transport information: Non-hazardous for air, sea and road freight.

Personal protection: None.

I think most of those claims are overblown. It's not that they're wrong; it's that the magnitude of each effect would be negligible.
posted by Steven C. Den Beste at 9:36 PM on October 5, 2007

I think most of those claims by the cosmetic company are overblown. (I think the MSDS is accurate.)
posted by Steven C. Den Beste at 9:37 PM on October 5, 2007

Consider also that the "heavy water mist" is quite possibly a very low concentration of actual heavy water. It's probably just mostly water-water, anyway.
posted by Cool Papa Bell at 9:39 PM on October 5, 2007

Be warned, I have NO knowledge of the biological effects of deuterated water.

The first thing that jumped out at me was the phrase "Its hydrogen molecule is twice the weight of the molecule in ordinary water". That's enough to tell you there was no chemist involved in the making of these claims. There is no "hydrogen molecule" in water. There are two hydrogen atoms. The claim that doubling their weight increases the weight of the water molecule by roughly ten percent is true. This does NOT mean that it will evaporate 10% more slowly.

"Heavy Water has a higher resistance to vaporization" - but how much higher? Wikipedia, not the most reliable of sources, I grant, shows their heats of vaporization to differ by something like 3%.

It is in fact true that D₂O has a greater viscosity than water. NIST data backs that up. I am skeptical that this has a noticeable effect on the skin, but see disclaimer above.

"It requires ten times as much energy to be ionized than regular water" - not according to NIST. To within the ranges of reported values, their ionization energies are the same (water, heavy water - you're looking for a column labeled "IE"). Note that "ionization energy" has a very specific meaning, and when they refer to its being ionized, they are probably referring to the molecule actually breaking, and even then, I would bet the difference isn't anything like that large, but I'm too lazy to keep looking things up. And if that is what they're referring to it's meaningless anyway, because breaking chemical bonds only happens with hard radiation - x-rays and beyond. And whether one molecule breaks at a lower energy than another is not directly related to what wavelengths in the UV the molecules absorb.

I can't speak intelligently to its effect on any bacteria, though googling indicates that there does seem to be a light-induced inactivation of the Propionibacterium acnes bacteria that is increased in the presence of deuterium oxide.

And finally, it's important to point out that as soon as heavy water hits the open air, it becomes less heavy. It trades some of its deuteriums for hydrogens with water molecules in the atmosphere. So even if every one of these claims were perfectly accurate, they would be claims about a substance that you won't, in fact, be using.
posted by solotoro at 10:05 PM on October 5, 2007

I'd vote bad idea for 4 reasons.

1. Heavy water is very expensive, much more expensive than the most over priced moisturizers. $300 per kilogram.

2. It's still going to evaporate faster than any glycerine or oil based moisturizer.

3. There are lots of things with higher ionization energies than heavy water and lots of things better at stopping UV radiation than heavy water, so who cares about those properties?

4. It's a mist, so you're going to be inhaling it. Where it will enter you lungs go straight to your heart and then into your brain. If there were two places I would not want high concentration of heavy water it would be my heart and my brain.
posted by 517 at 10:22 PM on October 5, 2007 [1 favorite]

$300/kg isn't actually more expensive than the most overpriced moisturizers
posted by LobsterMitten at 11:19 PM on October 5, 2007

Cost is prohibitive. You aren't getting a lot of heavy water.
posted by Ironmouth at 11:27 PM on October 5, 2007

I don't think it's a bad idea in the sense that it will actually harm you. I think it is a bad idea in the sense that it's going to cost you a lot and it won't actually do much good.

It's an expensive and mostly-ineffective gimmick, whose primary effects will result from confirmation bias and placebo effect.
posted by Steven C. Den Beste at 12:04 AM on October 6, 2007

Re the ionization, even if the claim were accurate, I don't think it's water you should worry about ionizing, rather DNA and such.
posted by hattifattener at 12:49 AM on October 6, 2007

I would be perfectly happy to bet ten thousand dollars that, like every other expensive skin product, these sprays are all completely fraudulent. The amount of heavy water in every one of them is very likely to be zero.

Theodore Gray's excellent Periodic Table Table site has a bottle of "D2O refreshing spray" as one of its samples. He points out that it's not actually legal to put heavy water in a foodstuff or cosmetic, not that there's any reason for anybody to do it or a significant risk of harm if someone did.

I find it difficult to understand why incredibly expensive beauty products sell so well. I've talked to women who acknowledge, perfectly frankly, that they understand that there is no quantifiable difference between $1000-a-kilo cream with a long list of techno-gibberish ingredients and the stuff that comes in a two litre pump pack for $5. But they still buy the expensive stuff.
posted by dansdata at 8:09 AM on October 6, 2007

$300/kg isn't actually more expensive than the most overpriced moisturizers

I'm guessing that $300/kg is just the cost to acquire heavy water. If it were put in moisturizer, then you'd have to consider the manufacturer's, distributor's and retailer's markup which at the end of the day is usually at least a factor of ten.
posted by randomstriker at 10:23 AM on October 6, 2007

Thanks, everyone for all the useful info.

That "hydrogen molecule" thing was definitely a red flag for me, but otherwise my knowledge of chemistry is pretty weak.
posted by oneirodynia at 5:41 PM on October 6, 2007