Share this article on:

Longitudinal Measures of PCBs and Thymus Size in Infants

Sonneborn, Dean*; Jusko, Todd; Park, Hye-Youn*; Palkovicova, Lubica; Nguyen, Danh§; Kocan, Anton; Trnovec, Tomas; Hertz-Picciotto, Irva*

doi: 10.1097/01.ede.0000362696.59705.d4
Abstracts: ISEE 21st Annual Conference, Dublin, Ireland, August 25–29, 2009: Symposium Abstracts

*University of California, Davis, Davis, California, United States; †School of Public Health ans Community Medicine, University of Washington, Seattle, Washington, United States; ‡Department of Environmental Medicine, Slovak Medical University, Bratislava, Slovakia; §Division of Biostatistics, Department of Public Health, University of California, Davis, Davis, California, United States; and ¶Department of Toxic Organic Pollutants, Slovak Medical University, Brataslava, Slovakia.


Back to Top | Article Outline

Background and Objectives:

Polychlorinated biphenyls (PCBs) are widespread environmental pollutants, despite having been banned for more than 20 years. Animal studies of PCB toxicity have demonstrated their immunotoxic effects, which include thymic atrophy and suppressed immune responses. We examined the association between pre- and postnatal PCB exposures and the estimated thymus volume in infants from eastern Slovakia, a highly contaminated region, at birth, 6 and 16 months of age.

Back to Top | Article Outline


Women were enrolled at delivery and blood samples were collected at this time and from the child at around 6 and 16 months of age for analysis of 15 PCB congeners and selected pesticides. Through interviews we obtained socio-demographic characteristics, lifestyle factors, and breastfeeding duration; we abstracted medical records for delivery variables and child’s growth. Thymus volume was calculated using ultrasound measurements of maximal transverse diameter (width) and largest sagittal area (length) at birth and again at approximately 6 and 16 months. The association between natural log thymus volume and natural log PCB (summed) concentration was estimated using linear regression, adjusted for potential confounders.

Back to Top | Article Outline


Thymus volume increases from birth to 6 months, peaks a few months later, and then declines. Higher PCB exposure was accompanied by smaller thymus volume, with the greatest reduction at the 6 month visit [24.3% for PCB increment from 10th to 90th percentile] and slightly smaller reductions at delivery [8.5%] and at 16 months [14.6%]. Male and Romani infants had significantly greater thymic size [10.6% and 3.1% respectively], and child’s weight was the strongest predictor of thymic volume. Alcohol and smoking resulted in reduced thymic volume of 3.3% and 2.9%, respectively.

Back to Top | Article Outline


The association of prenatal and early postnatal PCB exposure with reduced thymic size to at least the 16th month of age may reflect and/or result in impaired immunologic development.

© 2009 Lippincott Williams & Wilkins, Inc.