Associations between Prenatal Exposure to Polychlorinated Biphenyls and Neonatal Thyroid-Stimulating Hormone Levels in a Mexican-American Population, Salinas Valley, California

Details

• Alternative Title:
  Environ Health Perspect
• Personal Author:
  Chevrier, Jonathan ; Eskenazi, Brenda ; Bradman, Asa ; Fenster, Laura ; Barr, Dana B.
• Description:
  Background
  
  Studies have reported that prenatal exposure to polychlorinated biphenyls (PCBs) may alter neurodevelopment in both humans and animals. Furthermore, prenatal exposure to some PCB congeners and commercial mixtures has been shown to decrease free and total thyroxine (T4) blood levels in animals. Because thyroid hormones (TH) are essential for normal neurologic development, it has been suggested that the deleterious neurodevelopmental effect of PCBs may occur through TH disruption. PCBs may in turn affect TH levels by inducing the microsomal enzyme uridinediphosphate glucuronosyltransferase (UDP-GT), which is involved in TH elimination.
  
  Objectives
  
  Our goals were to group PCB congeners based on their potential to induce microsomal enzymes in animals, and to examine the relationship between neonatal TSH levels and prenatal exposure to PCB congeners grouped according to their structure and potential mechanisms of action.
  
  Methods
  
  We measured the concentration of 34 PCB congeners in serum samples collected from 285 pregnant women and the thyroid-stimulating hormone (TSH) levels in their children’s blood collected shortly after birth.
  
  Results
  
  We found no association between the sum of PCB congeners, the toxic equivalents, or structure-based groupings (mono- or di-ortho substituted congeners), and TSH blood concentration. However, we found a positive association between the sum of congeners suspected to be UDP-GT inducers (more specifically cytochrome P450 2B inducers) in animals and neonatal TSH levels. In individual congener analyses, PCBs 99, 138, 153, 180, 183, 187, 194, and 199 were positively associated with neonatal TSH levels after adjustment for covariates. PCBs 194 and 199 remained significant after adjustment for multiple hypothesis testing.
  
  Conclusions
  
  Our results support grouping PCB congeners based on their potential mechanism of action of enzyme induction when investigating associations with TH. Findings also suggest that PCBs affect TH homeostasis even at the low background level of exposure found in the CHAMA-COS (Center for the Health Assessment of Mothers and Children of Salinas) population.
  
  
• Subjects:
  Adolescent Adult Cohort Studies Cytochrome P-450 Enzyme System Environmental Exposure Female Glucuronosyltransferase Humans Infant, Newborn Mexican Americans Middle Aged Polychlorinated Biphenyls Pregnancy Prenatal Exposure Delayed Effects Thyrotropin

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• Source:
  Environ Health Perspect. 2007; 115(10):1490-1496.
• Document Type:
  Journal Article
• Funding:
  P01 ES009605/ES/NIEHS NIH HHS/United States ; R01OH007400/OH/NIOSH CDC HHS/United States
• Place as Subject:
  California
• Volume:
  115
• Issue:
  10
• NIOSHTIC Number:
  nn:20033338
• Collection(s):
  CDC Public Access National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:21d5d24add4f9ae869e565e3fc13076187ea7571ec6f7f685582387886b278331b1e5c850bb0114436702235b1ccc8a33e0354ec748e27b9c1773d64ac07f397
• Download URL:
  https://stacks.cdc.gov/view/cdc/31270/cdc_31270_DS1.pdf
• File Type:
  [PDF - 168.39 KB ]