June 23, 2016
The Journal of Allergy and Clinical Immunology
TAKE-HOME MESSAGE
- This study examined the link among domestic water hardness (CaCO3 mg/L), chlorine in water, skin barrier dysfunction, and atopic dermatitis (AD) in children. Infants 3-months old (N = 1303) were examined for AD and screened for filaggrin mutations, and transepidermal water loss was measured. Visible AD was significantly more common in children exposed to water with high CaCO3/low chlorine and high CaCO3/high chlorine compared with low levels of both CaCO3 and chlorine. High chlorine/low CaCO3 was not significantly associated with AD.
- High levels of domestic water calcium carbonate were associated with an increased risk of having visible eczema at 3 months of age. Future studies investigating intervention with devices that lower CaCO3in water are necessary.
– Sarah Churton, MD
Written by Eliot N Mostow MD, MPH
I love simple studies like this. It’s amazing that the investigators were able to recruit so many infants who had been screened for filaggrin mutations, but the UK must have good resources and funding for this. I’m afraid I don’t know a simple way to measure CaCO2 or chlorine in water to guide parents and patients, but it does make sense that anything that perturbs the skin-barrier function can increase atopic dermatitis flares in susceptible individuals. It really looks like the CaCO2 was the bigger issue and that the filaggrin mutation, at least at 3 months of age, didn’t matter too much.
The next time I see a child with AD, I’ll certainly mention this study as most parents are anxious to do anything they can to get any edge to improve their children’s problems. Good skin care surely trumps any change in water, but water hardness (with an unclear effect of chlorine) seemed to make a difference in this population. It was interesting that the filaggrin mutation was not really significant in this study.
Abstract
BACKGROUND
Domestic water hardness and chlorine have been suggested as important risk factors for atopic dermatitis (AD).
OBJECTIVE
We sought to examine the link between domestic water calcium carbonate (CaCO3) and chlorine concentrations, skin barrier dysfunction (increased transepidermal water loss), and AD in infancy.
METHODS
We recruited 1303 three-month-old infants from the general population and gathered data on domestic water CaCO3 (in milligrams per liter) and chlorine (Cl2; in milligrams per liter) concentrations from local water suppliers. At enrollment, infants were examined for AD and screened for filaggrin (FLG) skin barrier gene mutation status. Transepidermal water loss was measured on unaffected forearm skin.
RESULTS
CaCO3 and chlorine levels were strongly correlated. A hybrid variable of greater than and less than median levels of CaCO3 and total chlorine was constructed: a baseline group of low CaCO3/low total chlorine (CaL/ClL), high CaCO3/low total chlorine (CaH/ClL), low CaCO3/high total chlorine (CaL/ClH) and high CaCO3/high total chlorine (CaH/ClH). Visible AD was more common in all 3 groups versus the baseline group: adjusted odds ratio (AOR) of 1.87 (95% CI, 1.25-2.80; P = .002) for the CaH/ClL group, AOR of 1.46 (95% CI, 0.97-2.21; P = .07) for the CaL/ClH, and AOR of 1.61 (95% CI, 1.09-2.38; P = .02) for the CaH/ClH group. The effect estimates were greater in children carrying FLG mutations, but formal interaction testing between water quality groups and filaggrin status was not statistically significant.
CONCLUSIONS
High domestic water CaCO3 levels are associated with an increased risk of AD in infancy. The influence of increased total chlorine levels remains uncertain. An intervention trial is required to see whether installation of a domestic device to decrease CaCO3 levels around the time of birth can reduce this risk.
Journal Abstract