You may have seen the headlines all over the internet in the last week, proclaiming that new research shows that cleaning your baby’s pacifier by sucking on it after it is dropped may provide protection against developing allergies.
Of course, studies like this are often reported in the news in a way designed to get your attention and be exciting, not necessarily in a way that gets all the facts right. As usual, it’s worth taking a look to see what new data the study really shows and how it fits with existing high quality data.
As so often happens, we think we know something with a high level of certainty, and new information comes out that complicates or challenges existing beliefs. This data yet again challenges our modern American conception that favors keeping all germs away from babies at all times, even “protecting” them from run-of-the-mill household germs. This study appears to add to the growing body of evidence that keeping children in an ultra-clean environment is probably not helpful for children’s immune system as they grow up. Some exposure to dirt, garden-variety bacteria, and other microbes is normal.
If you look at humans through a historical lens, we did not live and grow in particularly germ free environments. The thought of trying to keep an infant from being exposed to the environment is not a logical development. Children crawl on the ground. They put everything into their mouths. Maybe this isn’t just a growth and development process; maybe it serves a bigger purpose in building a healthy immune system.
One thing we know very well from a body of well established research is that the spread of dental caries from mother to child is well documented. The microbes responsible for dental caries get transferred from the mother or primary caregiver quite readily. So, picking up a baby’s pacifier that fell onto the floor and putting it in the mother’s mouth to clean it is a clear avenue for transferring this disease, just like kissing, sharing drinks, sharing silverware, and other common human behaviors. One of the most important ways a mother can help prevent dental caries in her child is to have a healthy mouth herself. We shouldn’t just focus on treating the child, but need to address the disease in the mother as well.
It’s important to remember that this study is very limited and you really can’t draw significant conclusions from it. It does, however, further questions raised by the “hygiene hypothesis”. There was a similar report issued a few years ago that examined the 5-second rule. The 5 second barrier was shown to be quite arbitrary, not a meaningful measure of contamination or safety. Perhaps we should be less concerned about the contamination of things falling on the floor and more concerned about the contamination likely if mom has dental caries.