title: Endotoxin levels in rural Thai and urban Singaporean homes.
abstract: BACKGROUND
  Exposure to dust endotoxin and allergens in early childhood may influence the development of allergic diseases.
  
  
  OBJECTIVE
  This study aimed to evaluate dust endotoxin and dust mite allergens in urban Singapore and rural Thai homes of young children and study potential environmental influences.
  
  
  METHODS
  Mattress dust endotoxin and Der p 1, Der f 1, group 2 (Der f 2 and Der p 2) and Blo t 5 allergen levels were quantified in 101 infant mattress dust samples, 51 from urban Singapore and 50 from rural Thailand. Comprehensive questionnaires on the home environment and cleaning practices were completed.
  
  
  RESULTS
  Endotoxin levels in rural Thailand were significantly higher than in urban Singapore (geometric mean 26,334.12 +/- 4.60 and 18,377.85 +/- 2.52 endotoxin units/g, respectively; p = 0.032). In contrast, higher levels of Der f 1 (p = 0.02), group 2 (p < 0.01) and Blo t 5 (p < 0.01) allergens were found in Singapore homes compared with rural Thai homes. Multiple logistic regression analysis showed that the use of detergents (p = 0.001) and disinfectants (p = 0.024) to clean floors and mattress protectors (p = 0.021) were independently associated with lower endotoxin levels.
  
  
  CONCLUSIONS
  Endotoxin levels are higher in rural compared with urban homes in South East Asia. The reverse was true for dust mite allergen levels. Certain identifiable home environmental conditions and practices accounted for the differences in endotoxin levels.
authors.affiliation: Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: A
authors.initials: A
authors.lastname: Lee
authors.forename: P
authors.initials: P
authors.lastname: Sangsupawanich
authors.forename: S
authors.initials: S
authors.lastname: Ma
authors.forename: T-N
authors.initials: TN
authors.lastname: Tan
authors.forename: L P
authors.initials: LP
authors.lastname: Shek
authors.forename: D L M
authors.initials: DL
authors.lastname: Goh
authors.forename: B
authors.initials: B
authors.lastname: Ho
authors.forename: H
authors.initials: H
authors.lastname: van Bever
authors.forename: B W
authors.initials: BW
authors.lastname: Lee
mesh_terms: D016902:Air Pollution, Indoor; D000485:Allergens / Q000032:analysis*; D000818:Animals; D052179:Antigens, Plant; D004731:Endotoxins / Q000032:analysis*; D006798:Housing; D039981:Pyroglyphidae / Q000276:immunology*; D012424:Rural Population; D014505:Urban Population
chemical_list: D000485:Allergens; D052179:Antigens, Plant; D004731:Endotoxins; C094701:allergen Blo t 5