title: Endotoxin exposure in inner-city schools and homes of children with asthma.
abstract: BACKGROUND
  Endotoxins are stimulators of the immune system and, despite their potential to protect against allergy, have been associated with early wheezing and asthma morbidity.
  
  
  OBJECTIVE
  To compare inner-city school endotoxin exposure with home endotoxin exposure in children with asthma.
  
  
  METHODS
  Students with asthma were recruited from 12 urban elementary schools. Settled and airborne dust samples, linked to enrolled students, were collected from school classrooms, gymnasiums, and cafeterias twice during the academic year. For comparison, settled dust was collected once from the bedrooms of students with asthma.
  
  
  RESULTS
  Two hundred twenty-nine school settled dust samples and 118 bedroom settled dust samples were collected and analyzed for endotoxin. The median endotoxin concentration for school samples was 13.4 EU/mg (range, 0.7-360.7 EU/mg) and for home samples was 7.0 EU/mg (range = LLOD-843.0 EU/mg). The median concentration within each individual school varied from 6.6 EU/mg to 24.0 EU/mg. One hundred four students with asthma had matched classroom and bedroom endotoxin exposure measurements performed in the same season and demonstrated significantly higher concentrations of endotoxin in the students' classrooms (mean log value, 1.13 vs 0.99, P = .04). The median of the classrooms was 12.5 EU/mg compared with their bedrooms, with a median of 7.0 EU/mg. Within the school environment, no significant difference was seen between the fall and spring samples (mean log value 1.14 vs 1.09; P = .35).
  
  
  CONCLUSIONS
  Inner-city children with asthma were exposed to higher concentrations of endotoxin in their classrooms as compared with their bedrooms. Further studies are needed to evaluate school endotoxin exposure as a factor in asthma morbidity.
authors.affiliation: Department of Pediatrics, Division of Allergy and Immunology, Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Sheehan
authors.forename: Elaine B
authors.initials: EB
authors.lastname: Hoffman
authors.forename: Chunxia
authors.initials: C
authors.lastname: Fu
authors.forename: Sachin N
authors.initials: SN
authors.lastname: Baxi
authors.forename: Ann
authors.initials: A
authors.lastname: Bailey
authors.forename: Eva-Maria
authors.initials: EM
authors.lastname: King
authors.forename: Martin D
authors.initials: MD
authors.lastname: Chapman
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Lane
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Gaffin
authors.forename: Perdita
authors.initials: P
authors.lastname: Permaul
authors.forename: Diane R
authors.initials: DR
authors.lastname: Gold
authors.forename: Wanda
authors.initials: W
authors.lastname: Phipatanakul
mesh_terms: D000293:Adolescent; D016902:Air Pollution, Indoor; D000485:Allergens / Q000276:immunology*; D001249:Asthma / Q000453:epidemiology / Q000276:immunology*; D002648:Child; D004391:Dust / Q000276:immunology*; D004731:Endotoxins / Q000032:analysis* / Q000276:immunology; D005260:Female; D006798:Housing; D006801:Humans; D008297:Male; D008404:Massachusetts / Q000453:epidemiology; D012574:Schools; D012621:Seasons; D014505:Urban Population
chemical_list: D000485:Allergens; D004391:Dust; D004731:Endotoxins