Domestic water hardness and prevalence of atopic eczema in Castellon (Spain) schoolchildren

Water hardness has been associated with atopic eczema (AE) prevalence in two epidemiologic studies carried out on schoolchildren in England and Japan. Objective. To estimate the association between the prevalence of AE and domestic water hardness. Methods. The prevalence of AE was obtained from The International Study of Asthma and Allergies in Childhood, carried out in six towns in the province of Castellon on schoolchildren 6-7 and 13-14 years of age, using a standard questionnaire in 2002. Three zones were defined according to domestic water hardness of the six study localities: <200 mg/l, 200-250 mg/l,and >300 mg/l. A logistic regression analysis was performed. Results. The lifetime prevalence of AE in schoolchildren 6-7 years of age was higher with the increment of water hardness, 28.6, 30.5 and 36.5% respectively for each zone; between zone I and zone 3, the adjusted odds ratios (ORa) were 1.58 (95% Confidence Intervals [CI] 1.04-2.39) (adjusted tendency test p=0.034). Prevalence of symptoms of AE within the past year were 4.7,4.5, and 10.4%, respectively by zone; between zone I and zone 3, the OR was 2.29 (95% Cl 1.19-4.42) (adjusted tendency test p=0, 163)(a). For 13-14 year-old schoolchildren, tendencies to lifetime prevalence of AE at any time or in the past year were not significant. Conclusions. This study suggests that in 6-7 year-old schoolchildren, water hardness in the area where they live has some relevance to the development of the disease.