Related Experiment Video
Updated: May 20, 2026
In vivo Characterization of Endocrine Disrupting Chemical Effects via Thyroid Hormone Action Indicator Mouse
Published on: October 6, 2023
Environmental perchlorate and thiocyanate exposures and infant serum thyroid function
Angela M Leung1, Lewis E Braverman, Xuemei He
1Section of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, 88 East Newton St., Boston, MA 02118, USA. angela.leung@bmc.org
Insights
This study found that common environmental exposures like perchlorate and thiocyanate do not negatively impact thyroid function in breastfed infants. Iodine levels were sufficient in Boston-area mothers and their babies, easing concerns about these specific environmental factors.
Area of Science:
- Endocrinology
- Environmental Health
- Pediatrics
Background:
- Breastfed infants require maternal iodine for crucial neurodevelopment via thyroid hormone production.
- Iodine sufficiency in US childbearing women may be inadequate, raising concerns for infant health.
- Ubiquitous environmental perchlorate and thiocyanate can inhibit iodine uptake, potentially affecting thyroid function.
Purpose of the Study:
- To assess the relationship between environmental perchlorate and thiocyanate exposure and infant thyroid function.
- To determine if these environmental contaminants impact iodine availability for breastfed infants.
- To evaluate infant thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels in relation to exposure.
Main Methods:
- Cross-sectional study of 64 Boston-area mother-infant pairs (infants 1-3 months old).
- Measured iodine, perchlorate, and thiocyanate in breast milk, maternal urine, and infant urine.
- Analyzed correlations between contaminant levels and infant serum TSH and FT4.
Main Results:
- No significant correlations were found between infant TSH or FT4 and iodine, perchlorate, or thiocyanate levels.
- Perchlorate and thiocyanate levels in breast milk, maternal urine, and infant urine did not predict infant thyroid function.
- Boston-area mothers and infants in the study demonstrated sufficient iodine levels.
Conclusions:
- Maternal and infant exposure to environmental perchlorate and thiocyanate does not appear to affect infant thyroid function.
- The study suggests that iodine sufficiency is generally maintained in this population despite ubiquitous exposures.
- Concerns regarding the impact of these specific environmental contaminants on infant thyroid health are not supported by these findings.
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.
Related Concept Videos
01:20Synthesis and Regulation of Thyroid Hormones
Upon reaching the thyroid gland, TSH stimulates the follicular cells' active uptake of iodide ions from the blood. The ions diffuse to the apical surface of the cells and are oxidized to iodine. The iodine is then...
01:36Types of Toxins
Air pollutants, primarily gases, pose significant threats to respiratory health, leading to conditions like hypoxia, lung cancer, and in extreme cases, death.
Environmental pollutants like...
01:18Functions of Thyroid Hormones
TH is indispensable for the normal development and maturation of the skeletal, muscular, and nervous systems during fetal and childhood growth. It facilitates bone mineral turnover and regulates protein synthesis in developing tissues, contributing significantly to overall growth and...
01:07Teratogenicity
01:27Goiter
01:26Toxic Reactions: Overview
Toxicity falls into two primary categories: local and systemic.
Local toxicity appears at the exposure site, such as protein denaturation caused by caustic substances.
In contrast, systemic toxicity requires the toxic agent's absorption and distribution,...