title: Prenatal phthalate biomarker concentrations and performance on the Bayley Scales of Infant Development-II in a population of young urban children.
abstract: BACKGROUND
  Evidence suggests prenatal phthalate exposures may have neurodevelopmental consequences. Our objective was to investigate prenatal exposure to phthalates and cognitive development in a cohort of young urban children.
  
  
  METHODS
  We recruited pregnant women in New York City from 1998 to 2002 and measured concentrations of nine phthalate metabolites in urine collected in late pregnancy. We administered a neurodevelopmental screening instrument, the Bayley Scales of Infant Development II (BSID-II), to children who returned for follow-up at approximately 24 months (n=276). We estimated associations between phthalate metabolite concentrations in maternal urine and BSID-II indices (Mental Development Index (MDI), Psychomotor Development Index (PDI)).
  
  
  RESULTS
  We observed no associations between phthalate metabolite concentrations and performance on the MDI or PDI in boys and girls combined. We did, however, observe evidence of effect measure modification by sex. We observed several negative associations between metabolite concentrations and both MDI and PDI scores among girls, suggesting poorer performance across multiple metabolites, with estimates equal to a 2-3 point decrease in score per ln-unit increase in creatinine-standardized metabolite concentration. Conversely, we observed multiple weakly positive associations among boys, equal to a 1-2 point increase in score per ln-unit increase in metabolite concentration. The strongest associations were for the metabolites mono-n-butyl phthalate, mono-isobutyl phthalate, monobenzyl phthalate, and mono(3-carboxylpropyl) phthalate (MCPP).
  
  
  CONCLUSIONS
  Girls of mothers with higher urinary concentrations of MCPP and metabolites of dibutyl phthalates had lower MDI scores on the BSID-II. These same biomarker concentrations were often associated with improved scores among boys. We observed similar results for MnBP, MCPP, and MBzP on the PDI. Given the prevalence of phthalate exposures in reproductive aged women, the implications of potential neurotoxicity warrant further investigation.
authors.affiliation: Department of Epidemiology, University of North Carolina at Chapel Hill, 135 Dauer Drive, 2101 McGavran-Greenberg Hall, CB #7435, Chapel Hill, NC 27599, USA. Electronic address: bdoherty@live.unc.edu.
authors.forename: Brett T
authors.initials: BT
authors.lastname: Doherty
authors.affiliation: Department of Epidemiology, University of North Carolina at Chapel Hill, 135 Dauer Drive, 2101 McGavran-Greenberg Hall, CB #7435, Chapel Hill, NC 27599, USA.
authors.forename: Stephanie M
authors.initials: SM
authors.lastname: Engel
authors.affiliation: Department of Epidemiology, University of North Carolina at Chapel Hill, 135 Dauer Drive, 2101 McGavran-Greenberg Hall, CB #7435, Chapel Hill, NC 27599, USA.
authors.forename: Jessie P
authors.initials: JP
authors.lastname: Buckley
authors.affiliation: National Center for Environmental Health, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA 30329, USA.
authors.forename: Manori J
authors.initials: MJ
authors.lastname: Silva
authors.affiliation: National Center for Environmental Health, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA 30329, USA.
authors.forename: Antonia M
authors.initials: AM
authors.lastname: Calafat
authors.affiliation: Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, 1 Gustave Lane, Levy Plaza, New York, NY 10029, USA.
authors.forename: Mary S
authors.initials: MS
authors.lastname: Wolff
mesh_terms: D000328:Adult; D002657:Child Development; D002675:Child, Preschool; D003071:Cognition; D015331:Cohort Studies; D004781:Environmental Exposure; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000652:urine*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D018811:Maternal Exposure; D009519:New York City; D010795:Phthalic Acids / Q000652:urine*; D011247:Pregnancy; D011597:Psychomotor Performance; D014505:Urban Population; D055815:Young Adult
chemical_list: D004785:Environmental Pollutants; D010795:Phthalic Acids
keywords: Bayley Scales of Infant Development; Endocrine disruptor; Neurodevelopment; Phthalates; Prenatal