title: Association of serum concentrations of persistent organic pollutants with the prevalence of learning disability and attention deficit disorder.
abstract: OBJECTIVE
  Even though persistent organic pollutants (POPs) are well-known neurotoxicants, there is no previous study, even cross-sectional, on the association between background exposure to POPs and clinically significant developmental disorders, such as learning disability (LD) or attention deficit disorder (ADD), among children from a general population.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Study subjects were 278 children aged 12-15 years included in the National Health and Nutrition Examination Survey 1999-2000. The seven most commonly detected POPs (each detectable in >/=20% of children: 3,3',4,4',5-pentachlorobiphenyl; 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin (HPCDD); 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin (OCDD); 1,2,3,4,6,7,8-heptachlorodibenzofuran (HPCDF); beta-hexachlorocyclohexane; p,p'-dichlorodiphenyltrichloroethane; and trans-nonachlor) were selected.
  
  
  RESULTS
  Compared with children with non-detectable levels of POPs, adjusted prevalence ORs (95% CIs) of LD among those with detectable levels of HPCDD, OCDD or HPCDF were 2.08 ( 1.17 to 3.68), 2.72 (1.24 to 5.99) and 2.18 (1.15 to 4.15), respectively. For ADD, the corresponding figures were 3.41 (1.08 to 10.8), 3.33 (0.94 to 11.8) and 2.31 (0.62 to 8.63), respectively.
  
  
  CONCLUSIONS
  Associations were observed between serum concentrations of POPs belonging to the categories of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans and the prevalence of two clinically significant development problems, LD and ADD. The nature of these associations needs to be clarified by prospective studies.
authors.affiliation: Department of Preventive Medicine, School of Medicine, Kyungpook University, 101 Dongin-dong, Jung-gu, Daegu 700-422, Korea. lee_dh@knu.ac.kr
authors.forename: Duk-Hee
authors.initials: DH
authors.lastname: Lee
authors.forename: David R
authors.initials: DR
authors.lastname: Jacobs
authors.forename: Miquel
authors.initials: M
authors.lastname: Porta
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004785:Environmental Pollutants / Q000032:analysis / Q000097:blood; D005260:Female; D006801:Humans; D007859:Learning Disabilities / Q000453:epidemiology*; D008297:Male; D009930:Organic Chemicals / Q000032:analysis* / Q000097:blood; D014481:United States / Q000453:epidemiology
chemical_list: D004785:Environmental Pollutants; D009930:Organic Chemicals