title: Prenatal exposure to p,p'-DDE and p,p'-DDT in relation to lower respiratory tract infections in boys from a highly exposed area of Mexico.
abstract: BACKGROUND
  Prenatal exposure to 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE), the major breakdown product of DDT, has been associated with recurrent lower respiratory tract infections (LRTIs) in infants. However, epidemiological investigations are limited.
  
  
  OBJECTIVE
  To assess the association of prenatal exposure to p,p'-DDE and p,p'-DDT with the occurrence of LRTI in boys from Chiapas, a highly exposed area of Mexico.
  
  
  METHODS
  We analyzed data from 747 singleton boys whose prenatal exposure to p,p'-DDE and p,p'-DDT was determined in maternal serum drawn at delivery (2002-2003). LRTI (i.e., pneumonia, bronchiolitis, and other illness of the bronchi) experienced by the children were reported by their mothers during in-person interviews. The median age of the children when they were last seen was 21.4 months (quartiles 19.1 and 25.3 months).
  
  
  RESULTS
  Median exposure to p,p'-DDE in this population was higher (2.7 µg/g lipid) than recent U.S. levels (0.20 µg/g). There were 0.19 episodes of LRTI per child-year. After adjusting for potential confounders, children in the highest category of p,p'-DDE (>9.00 µg/g) exposure compared to those in the lowest (≤ 3.00 µg/g) had an adjusted incidence rate ratio (aIRR) of LRTI of 0.77 (95% confidence interval [CI], 0.41-1.46). The corresponding aIRR for p,p'-DDT (≥ 2.00 µg/g compared to ≤ 0.25 µg/g) was 0.65 (95% CI: 0.30-1.39).
  
  
  CONCLUSIONS
  An association of prenatal exposure to p,p'-DDE and p,p'-DDT with LRTI during childhood was not supported in this population with relatively high levels of exposure.
authors.affiliation: Center for Population Health Research, National Institute of Public Health, Cuernavaca 62100, Morelos, Mexico; Epidemiology Branch, National Institute of Environmental Health Sciences, NIH/DHHS/USA, Research Triangle Park, NC 27709, USA. Electronic address: lea.cupul@insp.mx.
authors.forename: Lea A
authors.initials: LA
authors.lastname: Cupul-Uicab
authors.affiliation: Center for Population Health Research, National Institute of Public Health, Cuernavaca 62100, Morelos, Mexico.
authors.forename: Efraín A
authors.initials: EA
authors.lastname: Terrazas-Medina
authors.affiliation: Center for Population Health Research, National Institute of Public Health, Cuernavaca 62100, Morelos, Mexico.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Hernández-Ávila
authors.affiliation: Epidemiology Branch, National Institute of Environmental Health Sciences, NIH/DHHS/USA, Research Triangle Park, NC 27709, USA.
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Longnecker
mesh_terms: D000293:Adolescent; D000328:Adult; D001991:Bronchitis / Q000139:chemically induced* / Q000453:epidemiology; D002675:Child, Preschool; D003634:DDT / Q000009:adverse effects*; D003633:Dichlorodiphenyl Dichloroethylene / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008297:Male; D008800:Mexico / Q000453:epidemiology; D011014:Pneumonia / Q000139:chemically induced* / Q000453:epidemiology; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D055815:Young Adult
chemical_list: D003633:Dichlorodiphenyl Dichloroethylene; D003634:DDT
keywords: Boys; Lower respiratory tract infections; Prenatal exposure; p,p′-DDE; p,p′-DDT
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