Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2009) 20 P507

ECE2009 Poster Presentations Endocrine Disruptors (10 abstracts)

The association between organochlorine compounds, iodine intake and thyroid hormones during pregnancy

Mar Alvarez-Pedrerol 1, , Mònica Guxens 1, , Àgueda Rodriguez 3 , Rosa Martorell 4 , Mercedes Espada 5 , Marisa Rebagliato 6 , Jesús Ibarlucea 5 & Jordi Sunyer 1,

1Centre for Research in Environmental Epidemiology, Barcelona, Spain; 2CIBER Epidemiologia y Salud Pública (CIBERESP), Barcelona, Spain; 3Hospital Parc Taulí, Sabadell, Spain; 4Hospital de Terrassa, Terrassa, Spain; 5Laboratorio Normativo de Salud Pública, Bilbao, Spain; 6Miguel Hernandez University, Valencia, Spain; 7Municipal Institute of Medical Research (IMIM-Hospital del Mar), Barcelona, Spain.

Objective: An adequate thyroid function during pregnancy is essential for the normal brain development of the foetus, and some organochlorine compounds (OCs) can interfere with the thyroid system. The objective of the present study was to evaluate the association between exposure to some OCs and thyroid function in pregnant women from two different areas in Spain, as well as to investigate the potential confounding effect of iodine intake.

Methods: Thyroid hormones (free T4 and T3) and TSH concentrations, and levels of polychlorinated biphenyls (PCB congeners 118, 138, 153 and 180), hexachlorobenzene (HCB), beta-hexachlorocyclohexane (β-HCH), dichlorodiphenyl dichloroethylene (p′p′-DDE) and dichlorodiphenyl trichloroethane (p′p-DDT) were measured in 1187 pregnant women from two population-based cohort studies. Urinary iodine concentrations (UIC) were analyzed in spot urine samples and iodine intake from diet, iodized salt and supplements were estimated from a food frequency questionnaire. The association between OCs (log-transformed) and thyroid parameters was assessed using linear regression models adjusted for potential confounders.

Results: Levels of HCB, β-HCH and PCBs (congeners 138, 180 and 153) were related to lower total T3 levels (adjusted coefficient (P value): −3.8 (P<0.001), −1.8 (P<0.05), −3.3 (P<0.01), −4.0 (P<0.001), and −4.1 (P<0.001), respectively) and higher free T4 levels (adjusted coefficient (P value): 0.014 (P<0.001), 0.010 (P<0.05), 0.010 (P<0.05), 0.018 (P<0.001), and 0.016 (P<0.001) respectively). The associations with total T3 were homogenously observed in both cohorts. Iodine intake was not related to OCs exposure.

Conclusions: Total T3 appears to be the main target of the toxicity of OCs during pregnancy. Moreover, iodine intake may not affect the association between OCs and TH.

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