BACKGROUND: Breastfed infants rely on maternal iodine for thyroid hormone production required for neurodevelopment. Dietary iodine among women of childbearing age in the United States may be insufficient. Perchlorate (competitive inhibitor of the sodium/iodide symporter [NIS]) exposure is ubiquitous. Thiocyanate, from cigarettes and diet, is a weaker NIS inhibitor. Environmental perchlorate and thiocyanate exposures could decrease breast milk iodine by competitively inhibiting NIS in lactating breasts (thus impairing infants' iodine availability), and/or infants' thyroidal NIS to directly decrease infant thyroid function. The current study assessed the relationships between environmental perchlorate and thiocyanate exposures and infant serum thyroid function. METHODS: Iodine, perchlorate, and thiocyanate in breast milk, maternal and infant urine, and infant serum thyroid function tests were cross-sectionally measured in Boston-area women and their 1-3 month-old breastfed infants. Univariate and multivariable analyses assessed relationships between iodine, perchlorate, thiocyanate, thyroid-stimulating hormone (TSH), and free thyroxine (FT4) levels. RESULTS: In 64 mothers and infants, median (range) iodine levels were 45.6 μg/L (4.3-1080) in breast milk, 101.9 μg/L (27-570) in maternal urine, and 197.5 μg/L (40-785) in infant urine. Median perchlorate concentrations were 4.4 μg/L (0.5-29.5) in breast milk, 3.1 μg/L (0.2-22.4) in maternal urine, and 4.7 μg/L (0.3-25.3) in infant urine. There were no correlations between infant TSH or FT4 and iodine, perchlorate, and thiocyanate levels in breast milk, maternal urine, and infant urine. In multivariable analyses, perchlorate and thiocyanate levels in breast milk, maternal urine, and infant urine were not significant predictors of infant TSH or FT4. CONCLUSIONS: Boston-area mothers and their breastfed infants are generally iodine sufficient. Although environmental perchlorate and thiocyanate are ubiquitous, these results do not support the concern that maternal and infant environmental perchlorate and thiocyanate exposures affect infant thyroid function.
BACKGROUND: Breastfed infants rely on maternal iodine for thyroid hormone production required for neurodevelopment. Dietary iodine among women of childbearing age in the United States may be insufficient. Perchlorate (competitive inhibitor of the sodium/iodide symporter [NIS]) exposure is ubiquitous. Thiocyanate, from cigarettes and diet, is a weaker NIS inhibitor. Environmental perchlorate and thiocyanate exposures could decrease breast milk iodine by competitively inhibiting NIS in lactating breasts (thus impairing infants' iodine availability), and/or infants' thyroidal NIS to directly decrease infant thyroid function. The current study assessed the relationships between environmental perchlorate and thiocyanate exposures and infant serum thyroid function. METHODS:Iodine, perchlorate, and thiocyanate in breast milk, maternal and infant urine, and infant serum thyroid function tests were cross-sectionally measured in Boston-area women and their 1-3 month-old breastfed infants. Univariate and multivariable analyses assessed relationships between iodine, perchlorate, thiocyanate, thyroid-stimulating hormone (TSH), and free thyroxine (FT4) levels. RESULTS: In 64 mothers and infants, median (range) iodine levels were 45.6 μg/L (4.3-1080) in breast milk, 101.9 μg/L (27-570) in maternal urine, and 197.5 μg/L (40-785) in infant urine. Median perchlorate concentrations were 4.4 μg/L (0.5-29.5) in breast milk, 3.1 μg/L (0.2-22.4) in maternal urine, and 4.7 μg/L (0.3-25.3) in infant urine. There were no correlations between infantTSH or FT4 and iodine, perchlorate, and thiocyanate levels in breast milk, maternal urine, and infant urine. In multivariable analyses, perchlorate and thiocyanate levels in breast milk, maternal urine, and infant urine were not significant predictors of infantTSH or FT4. CONCLUSIONS: Boston-area mothers and their breastfed infants are generally iodine sufficient. Although environmental perchlorate and thiocyanate are ubiquitous, these results do not support the concern that maternal and infant environmental perchlorate and thiocyanate exposures affect infant thyroid function.
Authors: U H Tazebay; I L Wapnir; O Levy; O Dohan; L S Zuckier; Q H Zhao; H F Deng; P S Amenta; S Fineberg; R G Pestell; N Carrasco Journal: Nat Med Date: 2000-08 Impact factor: 53.440
Authors: John H Lazarus; Jonathan P Bestwick; Sue Channon; Ruth Paradice; Aldo Maina; Rhian Rees; Elisabetta Chiusano; Rhys John; Varvara Guaraldo; Lynne M George; Marco Perona; Daniela Dall'Amico; Arthur B Parkes; Mohammed Joomun; Nicholas J Wald Journal: N Engl J Med Date: 2012-02-09 Impact factor: 91.245
Authors: J E Haddow; G E Palomaki; W C Allan; J R Williams; G J Knight; J Gagnon; C E O'Heir; M L Mitchell; R J Hermos; S E Waisbren; J D Faix; R Z Klein Journal: N Engl J Med Date: 1999-08-19 Impact factor: 91.245
Authors: Orsolya Dohán; Antonio De la Vieja; Viktoriya Paroder; Claudia Riedel; Mona Artani; Mia Reed; Christopher S Ginter; Nancy Carrasco Journal: Endocr Rev Date: 2003-02 Impact factor: 19.871
Authors: F Vermiglio; V P Lo Presti; M Moleti; M Sidoti; G Tortorella; G Scaffidi; M G Castagna; F Mattina; M A Violi; A Crisà; A Artemisia; F Trimarchi Journal: J Clin Endocrinol Metab Date: 2004-12 Impact factor: 5.958
Authors: J G Hollowell; N W Staehling; W H Hannon; D W Flanders; E W Gunter; G F Maberly; L E Braverman; S Pino; D T Miller; P L Garbe; D M DeLozier; R J Jackson Journal: J Clin Endocrinol Metab Date: 1998-10 Impact factor: 5.958
Authors: Joshua H Gordon; Angela M Leung; Andrea R Hale; Elizabeth N Pearce; Lewis E Braverman; Xuemei He; Mandy B Belfort; Sara M Nelson; Rosalind S Brown Journal: Thyroid Date: 2014-06-16 Impact factor: 6.568
Authors: Judy S LaKind; Geniece M Lehmann; Matthew H Davis; Erin P Hines; Satori A Marchitti; Cecilia Alcala; Matthew Lorber Journal: Environ Health Perspect Date: 2018-09 Impact factor: 9.031