Risk of eczema in infants may be related to water hardness: report

High levels of water hardness in the home may be linked to the development of eczema early in life, according to a study published Wednesday by King's College London.

Skin barrier impairment and dry skin are thought to be triggers of eczema in early life, partly through genetic predisposition. Environmental factors may also contribute to the breakdown of the skin barrier, including water hardness and chlorine in household water.

Previous studies in the UK, Spain and Japan have shown associations between domestic water hardness and the risk of eczema in schoolchildren. However, the link between water hardness and eczema has not been studied in early infancy.

To examine the link, a team led by researchers at the King's College London recruited 1,300 three-month old infants from families across the UK and gathered data on levels of calcium carbonate and chlorine in their household water from local water suppliers.

The infants were checked for childhood eczema and their skin's barrier function was assessed by measuring transepidermal water loss (TEWL) on the skin of an unaffected forearm. Infants were also screened for mutations in the filaggrin (FLG) gene, which codes for a key skin barrier protein.

The results showed that living in a hard water area was associated with up to 87 percent increased risk of eczema at three months of age, independent of domestic water chlorine content. The risk tended to be higher in children with mutations in the FLG skin barrier gene, although these latter results were not statistically significant.

"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," said Dr Carsten Flohr from King's College London, who is the lead author of the study.

But the study still has its limitations, such as the lack of information on children's exposure to swimming pools which contain much higher chlorine levels than domestic water.

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, said Flohr.

"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," added Flohr.

The study has been published in the Journal of Allergy and Clinical Immunology. Endit