Growth and thyroid function in children with in utero exposure to dioxin: a 5-year follow-up study

Area of Science:

• Environmental Health
• Endocrinology
• Developmental Pediatrics

Background:

• Placental polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs) exposure is linked to altered neonatal thyroid hormones.
• Understanding the long-term developmental effects of PCDD/Fs exposure is crucial.

Purpose of the Study:

• To assess the differential effects of maternal PCDD/Fs exposure on child development by gender at ages 2 and 5.
• To investigate the relationship between PCDD/Fs levels and key growth and hormone parameters.

Main Methods:

• Radioimmunoassay (RIA) was used to quantify thyroid, sex, and growth hormones.
• Follow-up of 92 mother and newborn pairs at ages 2 and 5, categorizing subjects into low or high PCDD/Fs exposure groups.
• Analysis of height, weight, BMI, head circumference, chest girth, bone age (BA), chronological age (CA), and hormone levels.

Main Results:

• Significant gender differences in growth parameters were observed at year 2, with males showing higher height and weight, and females higher chest girth.
• Girls exhibited a higher ratio of bone age to chronological age.
• PCDD/Fs levels significantly affected height, FT(4) x TSH, and transthyretin (TTR) at year 2, and height, triiodothyronine, and IGF-1 at year 5.
• Females showed significant differences in height, weight, CA, BA, and thyroid hormones at year 2 based on PCDD/Fs exposure.
• Males in the high PCDD/Fs group had significantly higher FT(4) x TSH at year 2 and IGF-1 at year 5.

Conclusions:

• In utero exposure to PCDD/Fs has differential effects on growth and hormone levels in male and female preschool children.
• Gender-specific developmental trajectories are influenced by prenatal exposure to environmental contaminants like PCDD/Fs.