title: Prenatal p,p'-DDE exposure and establishment of lateralization and spatial orientation in Mexican preschooler.
abstract: BACKGROUND
  Prenatal exposure to p,p'-DDE is associated with impairments in motor development during the first year of life, with no related repercussions on mental or motor development at 12-30 months and with impairments in cognitive areas, but not in perceptual and motor areas at preschool age. However, its association with particular psychomotor factors, such as establishment of lateralization and spatial orientation, essential elements to the overall learning and specifically reading, writing and spelling in preschoolers, has not been independently evaluated, since cognitive and motor areas have only been explored globally.
  
  
  OBJECTIVE
  To determine the association between prenatal exposure to p,p'-DDE and the establishment of lateralization and spatial orientation in children 5 years of age.
  
  
  METHODS
  Establishment of lateralization and spatial orientation was evaluated using the McCarthy Scale of Children's Abilities, with 167 children 5 years of age who participated in a birth cohort in the state of Morelos, Mexico. The information available for each child included: serum concentrations of p,p'-DDE of the mother during at least one trimester of pregnancy, mothers' intelligence quotients, stimulation at home and anthropometry. A logistic regression model was used to calculate the association between prenatal exposure to p,p'-DDE and lateralization and a multiple linear regression model was used for the association with spatial orientation.
  
  
  RESULTS
  A two-fold increase in p,p'-DDE in lipid base during the second trimester of pregnancy was associated with a significant reduction, -0.18 points (95% CI -0.41; 0.04, in the spatial orientation index, with no impairment in the establishment of hemispheric dominance. Attending preschool and the maternal intelligence quotient were the main determinants of spatial orientation and the establishment of hemispheric dominance.
  
  
  CONCLUSIONS
  Prenatal exposure to p,p'-DDE may affect the 5 year old's ability to identify spatial orientation of oneself and surrounding objects. Given the observed role of attending preschool in the functions studied, early attendance in formal education might serve as a stimulation strategy for preschoolers. These preliminary results should be verified and expanded in further prospective studies with DDE.
authors.affiliation: National Institute of Perinatology "Isidro Espinosa de los Reyes", México, D.F., Mexico. Electronic address: erikaosorio4@hotmail.com.
authors.forename: Erika
authors.initials: E
authors.lastname: Osorio-Valencia
authors.affiliation: National Institute of Public Health, Cuernavaca, Morelos, Mexico. Electronic address: ltorress@insp.mx.
authors.forename: Luisa
authors.initials: L
authors.lastname: Torres-Sánchez
authors.affiliation: National Institute of Public Health, Cuernavaca, Morelos, Mexico. Electronic address: lizbeth@insp.mx.
authors.forename: Lizbeth
authors.initials: L
authors.lastname: López-Carrillo
authors.affiliation: CINVESTAV Toxicology Department, México, D.F., Mexico. Electronic address: mcebrian@cinvestav.mx.
authors.forename: Mariano E
authors.initials: ME
authors.lastname: Cebrián
authors.affiliation: National Institute of Public Health, Cuernavaca, Morelos, Mexico. Electronic address: drlead@prodigy.net.mx.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Rothenberg
authors.affiliation: National Institute of Perinatology "Isidro Espinosa de los Reyes", México, D.F., Mexico. Electronic address: karmenhdez@hotmail.com.
authors.forename: María del Carmen
authors.initials: Mdel C
authors.lastname: Hernández Chávez
authors.affiliation: National Institute of Perinatology "Isidro Espinosa de los Reyes", México, D.F., Mexico. Electronic address: lschnaas@hotmail.com.
authors.forename: Lourdes
authors.initials: L
authors.lastname: Schnaas
mesh_terms: D002675:Child, Preschool; D003633:Dichlorodiphenyl Dichloroethylene / Q000009:adverse effects* / Q000097:blood; D005260:Female; D007839:Functional Laterality / Q000187:drug effects*; D006801:Humans; D007306:Insecticides / Q000009:adverse effects* / Q000097:blood; D007360:Intelligence / Q000187:drug effects; D008297:Male; D018811:Maternal Exposure; D008800:Mexico; D009483:Neuropsychological Tests; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000523:psychology*; D011446:Prospective Studies; D065855:Spatial Processing / Q000187:drug effects*
chemical_list: D007306:Insecticides; D003633:Dichlorodiphenyl Dichloroethylene
keywords: DDE; Lateralization; McCarthy Scales; Spatial orientation