Tessa A Mulder1, Michiel A van den Dries2, Tim I M Korevaar3, Kelly K Ferguson4, Robin P Peeters3, Henning Tiemeier5. 1. Generation R Study Group, Erasmus University Medical Center, Rotterdam, the Netherlands; Department of Internal Medicine, Academic Center for Thyroid Diseases, Erasmus University Medical Center, Rotterdam, the Netherlands; Department of Child and Adolescent Psychiatry, Erasmus University Medical Center, Rotterdam, the Netherlands. 2. Generation R Study Group, Erasmus University Medical Center, Rotterdam, the Netherlands; Department of Child and Adolescent Psychiatry, Erasmus University Medical Center, Rotterdam, the Netherlands. 3. Department of Internal Medicine, Academic Center for Thyroid Diseases, Erasmus University Medical Center, Rotterdam, the Netherlands. 4. Epidemiology Branch, Division of Intramural Research, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA. 5. Department of Child and Adolescent Psychiatry, Erasmus University Medical Center, Rotterdam, the Netherlands; Department of Social and Behavioral Science, Harvard TH Chan School of Public Health, Boston, USA. Electronic address: h.tiemeier@erasmusmc.nl.
Abstract
BACKGROUND: Animal studies suggest that organophosphate (OP) pesticides exposure affects thyroid function, but evidence in humans remains sparse and inconclusive. Gestational exposure is of particular interest, since thyroid hormone is essential for fetal brain development. OP pesticides are able to cross the placental and blood-brain barrier and may interfere with fetal development processes regulated by thyroid hormone. OBJECTIVE: To investigate the association of gestational OP pesticides exposure during pregnancy with maternal and cord blood thyroid hormone concentrations. METHODS: This study was embedded within Generation R (Rotterdam, the Netherlands), a prospective population-based birth cohort. Mother-child pairs with OP pesticides assessment and maternal (N = 715) or cord blood (N = 482) thyroid hormone measurements were included. OP pesticides exposure was assessed at <18, 18-25, and >25 weeks gestation by measuring six urinary dialkylphosphate (DAP) metabolites. Thyroid stimulating hormone (TSH) and free thyroxine (FT4) were measured in maternal and cord blood. Maternal measures also included total thyroxine (TT4) and TPO antibodies (TPOAbs). To study the association of creatinine-adjusted DAP metabolite concentrations with thyroid function and TPO antibodies, multivariable linear regression models including relevant confounders were used. RESULTS: There was no association of DAP metabolites with maternal TSH, FT4, TT4 or TPOAb concentrations during pregnancy. Similarly, there was no association of DAP metabolites with cord blood TSH or FT4. Results did not change when DAP concentrations were analyzed at individual time points or as mean gestational exposure. CONCLUSION: Gestational OP pesticides exposure, as assessed by repeatedly measured urinary DAP metabolite concentrations in an urban population, was not associated with maternal or cord blood thyroid hormone concentrations. These findings do not support a mediating role for serum thyroid hormone availability in the relation of early life exposure to low levels of OP pesticides with child neurodevelopment. However, disruption of the thyroid system at tissue level cannot be excluded. In addition, this is one of the first studies on this subject and measurement error in DAP metabolites might have resulted in imprecise estimates. Future studies should use more urine samples to increase precision and should investigate specific OP pesticide metabolites.
BACKGROUND: Animal studies suggest that organophosphate (OP) pesticides exposure affects thyroid function, but evidence in humans remains sparse and inconclusive. Gestational exposure is of particular interest, since thyroid hormone is essential for fetal brain development. OP pesticides are able to cross the placental and blood-brain barrier and may interfere with fetal development processes regulated by thyroid hormone. OBJECTIVE: To investigate the association of gestational OP pesticides exposure during pregnancy with maternal and cord blood thyroid hormone concentrations. METHODS: This study was embedded within Generation R (Rotterdam, the Netherlands), a prospective population-based birth cohort. Mother-child pairs with OP pesticides assessment and maternal (N = 715) or cord blood (N = 482) thyroid hormone measurements were included. OP pesticides exposure was assessed at <18, 18-25, and >25 weeks gestation by measuring six urinary dialkylphosphate (DAP) metabolites. Thyroid stimulating hormone (TSH) and free thyroxine (FT4) were measured in maternal and cord blood. Maternal measures also included total thyroxine (TT4) and TPO antibodies (TPOAbs). To study the association of creatinine-adjusted DAP metabolite concentrations with thyroid function and TPO antibodies, multivariable linear regression models including relevant confounders were used. RESULTS: There was no association of DAP metabolites with maternal TSH, FT4, TT4 or TPOAb concentrations during pregnancy. Similarly, there was no association of DAP metabolites with cord blood TSH or FT4. Results did not change when DAP concentrations were analyzed at individual time points or as mean gestational exposure. CONCLUSION: Gestational OP pesticides exposure, as assessed by repeatedly measured urinary DAP metabolite concentrations in an urban population, was not associated with maternal or cord blood thyroid hormone concentrations. These findings do not support a mediating role for serum thyroid hormone availability in the relation of early life exposure to low levels of OP pesticides with child neurodevelopment. However, disruption of the thyroid system at tissue level cannot be excluded. In addition, this is one of the first studies on this subject and measurement error in DAP metabolites might have resulted in imprecise estimates. Future studies should use more urine samples to increase precision and should investigate specific OP pesticide metabolites.
Authors: Joel Ehrenkranz; Phillip R Bach; Gregory L Snow; Alison Schneider; Jo Lynn Lee; Sarah Ilstrup; Sterling T Bennett; Salvatore Benvenga Journal: Thyroid Date: 2015-08 Impact factor: 6.568
Authors: Kim G Harley; Stephanie M Engel; Michelle G Vedar; Brenda Eskenazi; Robin M Whyatt; Bruce P Lanphear; Asa Bradman; Virginia A Rauh; Kimberly Yolton; Richard W Hornung; James G Wetmur; Jia Chen; Nina T Holland; Dana Boyd Barr; Frederica P Perera; Mary S Wolff Journal: Environ Health Perspect Date: 2015-12-18 Impact factor: 9.031
Authors: Michiel A van den Dries; Anjoeka Pronk; Mònica Guxens; Suzanne Spaan; Trudy Voortman; Vincent W Jaddoe; Todd A Jusko; Matthew P Longnecker; Henning Tiemeier Journal: Int J Hyg Environ Health Date: 2018-02-03 Impact factor: 5.840
Authors: Khairy A Ibrahim; Mohammed Eleyan; Heba Ali Abd El-Rahman; Soad A Khwanes; Rania A Mohamed Journal: Neurotox Res Date: 2020-02-08 Impact factor: 3.911
Authors: Zorimar Rivera-Núñez; Pahriya Ashrap; Emily S Barrett; Deborah J Watkins; Amber L Cathey; Carmen M Vélez-Vega; Zaira Rosario; José F Cordero; Akram Alshawabkeh; John D Meeker Journal: Environ Int Date: 2020-12-13 Impact factor: 9.621