Recently, I came across an interesting article with the following title: Pacifier Cleaning Practices and Risk of Allergy Development. Health authorities in the past have told Mums that cleaning their babe’s pacifier under running water or by boiling is the best way to avoid transferring harmful bacteria from her mouth to her little one (bacteria like Strep mutans, the one that causes cavities, in particular). This article challenges previous recommendations, caused me to stop and say “hmm..” and think a little about early childhood exposures and allergies. The author’s overall conclusion is that children whose parents “cleaned” their pacifier by sucking it were less likely to develop allergies and eczema when compared to children whose parents did not. In fact, protection against eczema lasted statistically until 36 months of age. But why?
The prevalence of atopic (IgE-mediated allergic) conditions over the 20th century has skyrocketed – today, nearly 1 in 3 children in affluent countries suffers from asthma, eczema or other reaction to an inhaled or ingested agent. These allergies result because the child’s immune system is over-reacting to an external agent that should normally not cause any issue, and the ‘hygiene hypothesis’ is generally cited as the cause. In case you don’t know, the hygiene hypothesis is the idea that over-cleaning and sanitizing everything that a baby interacts with reduces their exposure to microbes that assist in proper immune system development. It’s also known as the “clean mother” hypothesis.. but moving on. If the immune system doesn’t develop as it should, when it encounters a new agent (like peanuts or pollen), the immune system over-reacts and causes the symptoms of allergies/eczema/asthma.
Children are born lacking the necessary beneficial bacteria in their gut, and gain them over time through environmental exposures. These bugs help to stimulate development of the immune system, the majority of which is housed in the intestines. And it takes a fully mature immune system to not over-react to new environmental agents.
There are several examples of why the hygiene hypothesis is likely correct:
We have known for quite some time that children who are vaginally delivered have lower risks of developing atopic conditions like allergies when compared to babies delivered via cesarean section. This is attributed this to the exposure of the babe to various microbes as he/she travels out of the birth canal.
Poverty, crowded housing, large families, living on a farm, and exposure to food-borne microbes are also associated with fewer allergies. Studies have even shown that children who live with household pets, dogs in particular, have stronger immune systems than those who do not.
Young children who have older siblings in daycare tend to experience more frequent colds and flus, but after the age of six these same children are 40% less likely to be suffering with asthma.
What do vaginal delivery, crowded housing, pets and daycare have in common? It’s “un-hygienic..” but the answer is exposure to microbes.
The article also debunks the popular myth that swapping spit with your babe will increase their prevalence of cavities – it says that “caries [cavities] seem to be unrelated to pacifier use, and may even be negatively associated with ‘close’ salivary contact between infant and patient.” And further – “transfer of a complex microbiota from parent to infant may help to build up resistance to colonization with more pathogenic bacteria.” Stop worrying about giving your child cavities – you’re likely giving greater protection against them in the future by being liberal with close contact, kisses, and sharing utensils.
The overall message is that perhaps our 20th century ideal of “the cleaner, the better” and our behaviours of stocking the cabinets with Lysol and Javex are a little off-base. There is something to be said for letting babes eat dirt – or at least, not breaking out the hand sanitizer when your kid touches a little dirt.
So go ahead, suck that pacifier clean! You’ll be doing your child a favour.
Dr. Kali MacIsaac ND HBSc
Article reference: Hesselmar B, et al. Pacifier cleaning practices and risk of allergy development. Pediatrics, 2013: 131:6. Retrieved June, 2013: http://pediatrics.aappublications.org/content/early/2013/04/30/peds.2012-3345.full.pdf+html