Hard water in home linked to eczema in infancy

High levels of calcium carbonate in domestic water appear to be associated with an increased risk of atopic dermatitis in infancy, according to a new study.

Whether or not the level of chlorine in domestic water impacts eczema risk in infancy remains unclear. And further study is needed to better understand if using a water purifier to decrease residential calcium carbonate levels in water around the time of birth might reduce the increased risk, researchers from Kings College of London report.

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

Studies have shown links between domestic water hardness and the risk of eczema in schoolchildren. But the association between water hardness and eczema has not been studied in early infancy, according to a Kings College of London press release on the study.

Researchers recruited 1,300 three-month old infants from families across the U.K., gathering information about levels of calcium carbonate and chlorine in household water from local suppliers. The children were taking part in a study looking at how to prevent food allergies in young children.

Researchers checked the infants for atopic dermatitis and assessed subjects’ skin barrier function by measuring transepidermal water loss (TEWL) on the skin of an unaffected forearm. They also screened for filaggrin gene mutations.

They found that living in a hard water area was associated with up to 87% increased risk of eczema at three months of age, independent of the domestic water’s chlorine content. The risk tended to be higher (but not statistically significant) in children with filaggrin gene mutations.

NEXT: Evidence building

Evidence building

“Our study builds on growing evidence of a link between exposure to hard water and the risk of developing eczema in childhood. It’s not yet clear whether calcium carbonate has a direct detrimental effect on the skin barrier, or whether other environmental factors directly related to water hardness, such as the water’s pH, may be responsible,” the study’s lead author Carsten Flohr, M.D., from St John’s Institute of Dermatology at King’s College London and Guy’s and St Thomas’ NHS Foundation Trust, says in the press release.

“Interactions between hardness and chlorine levels, other chemical water constituents and the skin’s microflora may also play a role, and this warrants further research. We are about to launch a feasibility trial to assess whether installing a water softener in the homes of high risk children around the time of birth may reduce the risk of eczema and whether reducing chlorine levels brings any additional benefits,” Dr. Flohr says.

This is an interesting and credible study of infants, suggesting there probably is a link, according to A. Yasmine Kirkorian, M.D., assistant professor of dermatology and pediatrics, at Children's National Health System, George Washington University School of Medicine & Health Sciences, Washington, D.C.

“Their study had multiple strengths. First, they evaluated all of the children in person to diagnose and score the severity of their eczema (other studies have relied on parental surveys which are not as objective or standardized). Second, they tested for mutations in the gene filaggrin, which is a known risk factor for eczema. Third, they evaluated children from all over the UK so they were able to compare areas with high rates of hard water to low rates of hard water,” Dr. Kirkorian tells Dermatology Times. “I think their data is intriguing regarding a possible link between hard water and eczema. They postulate that hard water might provoke or unmask eczema due to disruption of the skin barrier or possibly due to an interaction of the calcium in the water with filaggrin.”

Dr. Kirkorian agrees with the study’s authors that it’s probably too early to suggest that families install water softeners.

“As they note in their paper, a previous randomized trial of use of water softeners in the UK failed to show benefit. The authors hypothesized that this was because the Softened Water Eczema Trial used ion-exchange water softeners which removed the hard water but didn't remove chlorine. The role of chlorine in exacerbation of eczema is unclear but is interesting,” Dr. Kirkorian says.

“For now," she says, "I think it's too soon to recommend water softeners. However, if families have the ability and desire to purchase a water softener, I think we can cautiously support that intervention as an additional step beyond the critical dry skincare instructions we already provide. It remains to be seen whether we'll be recommending water softeners and chlorine filters one day.”

Disclosures: Drs. Flohr and Kirkorian report no relevant disclosures.