Early life air pollution exposures and thyroid function in children: A prospective cohort study

Area of Science:

• Environmental Health
• Pediatric Endocrinology
• Toxicology

Background:

• Limited research exists on early life ambient air pollution and childhood thyroid function.
• Fine particulate matter (PM2.5) and nitrogen dioxide (NO2) are common air pollutants with potential health impacts.
• Thyroid hormones are crucial for child development.

Purpose of the Study:

• To investigate the relationship between early life exposure to PM2.5 and NO2 and thyroid function in children.
• To analyze how exposure timing (gestational vs. childhood) influences these associations.

Main Methods:

• Longitudinal study of 684 children in a rural Korean cohort (2012-2020).
• Measurement of thyrotropin (TSH), triiodothyronine, and free thyroxine levels at ages 2, 4, 6, and 8 years.
• Estimation of residential average PM2.5 and NO2 exposure during pregnancy and the year prior to assessment.

Main Results:

• Increased PM2.5 during the first trimester was inversely associated with TSH levels at ages 4 and 6 years.
• Childhood PM2.5 exposure was positively associated with TSH levels at ages 4 and 6 years.
• Childhood PM2.5 exposure was inversely associated with free thyroxine levels at age 8 years; no NO2 associations were found.

Conclusions:

• PM2.5 exposure timing influences childhood thyrotropin levels, with gestational exposure showing an inverse relationship and childhood exposure a positive one.
• The findings highlight the complex effects of air pollution on the developing thyroid.
• Further research is needed to explore long-term effects and underlying mechanisms of air pollution on thyroid function.