I am blogging early this week because of the timely nature of a post beginning to circulate on social media. A woman in New York is posting pictures of her young child and is making the claim the marks on the skin of her child is due to the chemical inside the diaper leaking out and being in contact with her baby’s skin during a nap along the child’s leg under the pants. It appears the photo is real and I have no reason to believe her claim is false at this point. I have contacted this mom via Facebook to try to add some plausibility to my hypothesis, but at this point I have not heard back from her. I will update the post if I do.There is a possible explanation, and perhaps one that should be investigated so parents can exercise caution if it turns out to be correct. My thought on this is there is indeed a chemical burn happening, but it isn’t the diaper alone that is causing it. I believe there is a perfect storm of chemicals that, while rarely, can be present in the right rations to cause this type of injury.
Snopes reports that as early as 2010, after a change in the design of a particular brand of diapers, parents began reporting burn injuries which they correlated to the change of the diaper design. One can do a Google search and find hundreds of blog posts on the warm and fuzzy parenting sites about changing to “chemical-free” diapers. I’m not sure how one creates a chemical-free diaper, since even having the air be the diaper, the air is still a chemical. Both Canadian and U.S. authorities investigated the claims at that time, and found no cause for concern. Proctor & Gamble did settle a lawsuit out of court, which gave a small amount of money to those families and covered the legal fees. This is often standard to settle rather than pay much higher costs fighting the claims in court.
Sodium polyacrylate is the stuff inside diapers that allows it to absorb super amounts of water. Carnegie Mellon University gives a nice simple explanation on their teacher resource page on the material:
Sodium polyacrylate is an example of a super-absorbing polymer. It is a cross-linked (network) polymer that contains sodium atoms. It absorbs water by a process called osmosis. When the (sodium-containing) polymer is placed in contact with water, there is a tendency for the sodium to distribute equally between the network and the water. That means, some of the sodium atoms want to leave the network and move to the water. When these sodium atoms leave, they are replaced with water molecules. Water swells the polymer network to try to keep the sodium concentration balanced between the polymer and the water. The cross-links that connect the chains together prevent them from dissolving/breaking apart in the water. Sodium polyacrylate can absorb 800 times its weight in distilled water, but only 300 times its weight in tap water, since tap water contains some sodium, calcium and other mineral salts.
The MSDS indicates that sodium polyacrylate dust is an eye and lung irritant. This should make sense, because those are both moist environments, so the dust would absorb water, causing eye dryness and bronchial dryness, as well as swelling up and causing the body to try to get rid of the stuff. This doesn’t explain chemical burns.
The other precaution mentioned in the MSDS is to avoid strong oxidizing agents. Although I couldn’t find anything in several minutes of searching as to why this is, I hypothesize what is happening is the oxidizing agent would strip off the ionic end of the polymer (the sodium) and in the presence of the water in the urine will form sodium hydroxide. When raw sodium contacts water, a very exothermic reaction happens, and in the process sodium hydroxide and hydrogen is formed.
What could be the oxidizing agent? Again, this is conjecture, but a common item for households with young children who soil their clothes often is non-chlorine bleach. These products generally contain peroxides and/or carbonates. These do indeed produce oxygen when exposed to water. My own anecdote is young kids produce bushels full of laundry. I will often fill the machine a bit more than maybe it should be. It is entirely possible some of these oxygenating cleaners were not entirely dissolved and were left on the clothes. As the diaper leaked, the interaction with water released the oxygen, causing the sodium to detach from the sodium polyacrylate and forming sodium hydroxide in the water.
In this case, I am going to say that snopes got it right from the media reports, the reports from government agencies, and the court cases. However, I do see a plausibility that I don’t think has been tested. The circumstances would need to be perfect, which is likely why we don’t see this more often. However, I do think it is worth testing, and perhaps issue some advice on making sure to avoid using oxygen cleaners or make sure to thoroughly rinse clothing washed in such substances.
I hope someone does the science on my hypothesis.
Update: Snopes has a follow-up piece specifically about this case. They state that while the burns are probably not fake, they do a great job of explaining the logical fallacy in assuming it is the diaper.
Update 11/7/2013: An initial test mixing about 2 teaspoons of the sodium polyacrylate and a similar amount of a brand name sodium percarbonate detergent and 100 mL of water did indeed give an increase in pH to just over 11. This seems to be consistent with the known pH of solid sodium percarbonate mixed with water. Further review of the research indicated that sodium percarbonate alone can cause skin irritation, due partially to the pH and partially to the release hydrogen peroxide, which is known to damage skin with extended contact. Keep in mind this ingredient is in many of the detergents commonly used by consumers.
This initial test was done more as an observation and did not have controls or multiple tests due to time constraints. However, Dr. Emily Flynn and other fellow faculty (thanks to them for helping!!) are helping me set up further tests, which I will follow up on in the near future. It does appear on initial observation that my hypothesis has validity.