TABLE 2.

Summary of Epidemiologic Data on Associations Between Levels of PCBs and Measures of Thyroid Hormone Economy From the Dietary Exposure Studies24

CountryPopulation and Year Specimens CollectedReferenceMean Age (Years)Measure of Association With PCBs
nTotal TriiodothyronineFree TriiodothyronineTotal ThyroxineFree ThyroxineThyroid-Stimulating HormoneRadioiodine Triiodothyronine Update
Children
 Rotterdam, Netherlands105 mother–infant pairs; 1990–199223*078NSNMNSNMr = 0.38NM
 Netherlands93 mother–infant pairs; 199326093NMNMNSNMNMNM
 North Carolina160 infants with samples available (from cohort of 900); 1978–1982270160NMNMr = 0.07r = −0.12r = −0.08NM
 Faeroe Islands, Denmark182 infant–mother pairs; 1994–1995250182NMNSNSNSr = −0.04r = −0.21
 Hessen, Germany320 school children 7–10 years of age; 1994–1995288296NMβ = −0.25NMβ = 7.13§NM
Mothers
 Rotterdam, Netherlands105 mother–infant pairs; 1990–1992232978r = −0.36NMNSNMNSNM
 Faeroe Islands, Denmark182 infants and mothers, 1994–19952528182NMNSNSNSr = −0.13NS
  • NS indicates association not statistically significant; NM, not measured; r, correlation coefficient; β, regression coefficient.

  • * Results shown are for nonplanar PCB toxic equivalents, but results were described as being similar for nonplanar PCBs.

  • Association statistically significant (P < .05).

  • Nonlinear association (no strong evidence of any association).

  • § Association with PCB 118 only statistically significant (P < .05); association with other PCBs nonlinear and not statistically significant.

  • Adapted with permission from Longnecker MP. Endocrine and other human health effects of environmental and dietary exposure to polychlorinated biphenyls (PCBs). In: Robertson LW, Hansen LG, eds. Recent Advances in the Environmental Toxicology and Health Effects of PCBs. Lexington, KY: University of Kentucky Press; 2001:114.