title: Pre- and postnatal polychlorinated biphenyl concentrations and longitudinal measures of thymus volume in infants.
abstract: BACKGROUND
  Previously, we reported an association between higher maternal polychlorinated biphenyl (PCB) concentrations and smaller thymus volume in newborns in a birth cohort residing in eastern Slovakia.
  
  
  OBJECTIVE
  In the present report we address whether thymus volume at later ages is influenced by prenatal and early postnatal PCB exposure.
  
  
  METHODS
  At the time of delivery, 1,134 mother-infant pairs were enrolled. Maternal and 6- and 16-month infant blood samples were collected and analyzed for 15 PCB congeners. Thymus volume was measured in infants shortly after birth and at ages 6 and 16 months using ultrasonography.
  
  
  RESULTS
  Higher maternal PCB concentration was associated with reduced thymus volume at birth [a 0.21 SD reduction in thymus volume for an increase in total maternal PCB concentration from the 10th to the 90th percentile; 95% confidence interval (CI): -0.37, -0.05], whereas maternal PCB concentration was not predictive of 6- and 16-month thymus volume. Six-month infant PCB concentration was associated with a 0.40 SD decrease in 6-month thymus volume (95% CI: -0.76, -0.04). There was also some suggestion that thymus volume at 16 months was positively associated with concurrent infant PCB concentration.
  
  
  CONCLUSIONS
  The potential adverse effects of in utero PCB exposure on thymic development may extend beyond the neonatal period. Results from this highly exposed cohort provide suggestive evidence that postnatal PCB concentrations may be influential, but a smaller set of 6-month PCB measurements limited statistical power at that time point. Implications regarding impaired immunologic maturation or long-term clinical implications remain to be determined.
authors.affiliation: Epidemiology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina 27709-2233 , USA. todd.jusko@nih.gov
authors.forename: Todd A
authors.initials: TA
authors.lastname: Jusko
authors.forename: Dean
authors.initials: D
authors.lastname: Sonneborn
authors.forename: Lubica
authors.initials: L
authors.lastname: Palkovicova
authors.forename: Anton
authors.initials: A
authors.lastname: Kocan
authors.forename: Beata
authors.initials: B
authors.lastname: Drobna
authors.forename: Tomas
authors.initials: T
authors.lastname: Trnovec
authors.forename: Irva
authors.initials: I
authors.lastname: Hertz-Picciotto
mesh_terms: D000328:Adult; D002849:Chromatography, Gas; D015331:Cohort Studies; D004781:Environmental Exposure; D004785:Environmental Pollutants / Q000097:blood / Q000633:toxicity*; D005260:Female; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D008297:Male; D018811:Maternal Exposure / Q000009:adverse effects*; D015999:Multivariate Analysis; D009929:Organ Size / Q000187:drug effects; D011078:Polychlorinated Biphenyls / Q000097:blood / Q000633:toxicity*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000139:chemically induced / Q000453:epidemiology*; D018154:Slovakia / Q000453:epidemiology; D013950:Thymus Gland / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000254:growth & development; D014463:Ultrasonography; D055815:Young Adult
chemical_list: D004785:Environmental Pollutants; D011078:Polychlorinated Biphenyls