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Published on: August 7, 2017
Pre- and postnatal polychlorinated biphenyl concentrations and longitudinal measures of thymus volume in infants
Todd A Jusko1, Dean Sonneborn, Lubica Palkovicova
1Epidemiology 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
Insights
Prenatal exposure to polychlorinated biphenyls (PCBs) may impact thymus development beyond birth. Postnatal PCB levels also showed potential effects on thymus volume in infants, warranting further investigation.
Area of Science:
- Environmental Health
- Toxicology
- Immunology
Background:
- Previous research linked higher maternal polychlorinated biphenyl (PCB) concentrations to reduced thymus volume in newborns.
- This study investigates the impact of prenatal and early postnatal PCB exposure on thymus volume at later infant ages.
Purpose of the Study:
- To determine if prenatal and early postnatal polychlorinated biphenyl (PCB) exposure influences thymus volume in infants at 6 and 16 months of age.
Main Methods:
- Enrolled 1,134 mother-infant pairs at delivery.
- Collected maternal and infant blood samples at birth, 6, and 16 months for PCB analysis.
- Measured infant thymus volume via ultrasonography at birth, 6, and 16 months.
Main Results:
- Higher maternal PCB levels correlated with smaller thymus volume at birth.
- Six-month infant PCB concentrations were associated with reduced 6-month thymus volume.
- A positive association was suggested between 16-month thymus volume and concurrent infant PCB levels.
Conclusions:
- Adverse effects of in utero PCB exposure on thymic development may persist beyond the neonatal period.
- Postnatal PCB concentrations might influence thymic development, though statistical power was limited.
- Further research is needed to determine long-term clinical implications for immunologic maturation.
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.
