We restrictedthe study population to residents of the sub-district who livedwithin 40 km of the IP (Fig. 1). All resident children aged 0–14 yearswho were admitted to the regional Soroka Medical Center between2004 and 2009 were included. Of the eligible admissions weexcluded 245 newborn admissions and 52 admissions in hemato-oncology units. Participants with unknown addresses of residence(n = 20) or unknown gender (n = 2) were also excluded from thestudy population. For children with more than one admission (13%of all children included in the study) the earliest admission wasconsidered