title: Incidence of Pediatric Inflammatory Bowel Disease in Finland: An Environmental Study.
abstract: The aim of this study was to explore possible environmental factors behind the regional differences in the incidence of pediatric inflammatory bowel disease (IBD).
  
  
  
  All of the patients diagnosed with IBD who were aged 0 to 14 years in Finland between 1987 and 2003 were identified from the Social Insurance Institution database. Finland was divided into squares of 250 × 250 m, and spatial variations of incidence rates were evaluated accordingly. The role of the environmental determinants (pediatric population density, agricultural industry, chemical contaminants of tap water and proximity to the sea or paper mills) in the geographic variations of the incidence rates was evaluated.
  
  
  
  During the study period, the overall incidence of pediatric IBD was 6.5 of 100,000 (95% confidence interval [CI] 6.1-6.9). The incidence in very sparsely populated areas (≤10 person-years per 250 × 250 m) was 9.2 of 100,000 (95% CI 6.3-13.1) and 5.6 of 100,000 (95% CI 4.8-6.4) in the districts with the highest population density (>800 person-years per 250 × 250 m). A nonsignificant trend toward the same direction was also seen for ulcerative colitis (trend P = 0.09). Chemical contaminant concentrations of tap water, residence near the seaside, or proximity to paper mills were not associated with the incidence of pediatric IBD.
  
  
  
  Our findings suggest higher incidence rates of pediatric IBD in the districts with low compared with high density of child population, but the differences cannot be explained by variations in the environmental exposures evaluated here.
authors.affiliation: *Department of Clinical Physiology, Tampere University Hospital†Tampere Centre for Child Health Research, University of Tampere, Tampere‡National Institute for Health and Welfare, Kuopio§Children's Hospital, Helsinki University Hospital and University of Helsinki, Helsinki||Department of Public Health, University of Tampere, Tampere, Finland.
authors.forename: Pieta
authors.initials: P
authors.lastname: Lehtinen
authors.forename: Kari
authors.initials: K
authors.lastname: Pasanen
authors.forename: Kaija-Leena
authors.initials: KL
authors.lastname: Kolho
authors.forename: Anssi
authors.initials: A
authors.lastname: Auvinen
mesh_terms: D000293:Adolescent; D002648:Child; D000067576:Child Health; D002675:Child, Preschool; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D015212:Inflammatory Bowel Diseases / Q000453:epidemiology* / Q000209:etiology; D008297:Male