Domestic hard water increases eczema prevalence in adults

Increased exposure to domestic water with high mineral content — or domestic hard water — increased prevalence but not incidence of eczema in adults, according to a study.

One of the known environmental risk factors for eczema is domestic hard water, formed when minerals, particularly calcium in the form of calcite (CaCO₃) and dolomite, are dissolved in water from filtration through sedimentary rocks.

“We calculated that approximately 451 eczema cases per 10,000 people in the U.K. could be attributable to domestic hard water,” Diego J. Lopez, DDS, MPH, of the allergy and lung health unit at the University of Melbourne in Australia, told Healio.

Diego J. Lopez

Using UK Biobank Study data from 2006 through 2013, Lopez and colleagues examined the association between domestic hard water supply and eczema in 306,531 adults (mean age, 57 years; range, 40-69). Questionnaires and nurse-led interviews determined eczema prevalence at baseline and at follow-up. CaCO₃ concentrations were obtained from local water supply companies in England, Wales and Scotland in 2005 and 2013.

According to the study, an increase in domestic hard water positively correlated with increased odds of prevalent eczema at baseline (OR = 1.02; 95% CI, 1.01-1.04). Furthermore, participants exposed to hard water with CaCO₃ concentrations greater than 200 mg/L had increased odds of prevalent eczema at baseline (OR = 1.12; 95% CI, 1.04-1.22) compared with participants exposed to lower concentrations.

The researchers found a significant linear trend (P < .001) that showed increasing levels of hard water exposure were associated with increased prevalent eczema risk at baseline. However, there was no association found between domestic hard water and incident eczema or eczema at follow-up.

“Higher domestic hard water concentration exposure is associated with an increase in eczema prevalence in middle-aged adults,” Lopez said. “Ongoing efforts to reduce hard water exposure may have a beneficial effect in reducing eczema prevalence in adults.”