Growth and thyroid function in children with in utero exposure to dioxin

Because placental polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs) levels are associated with decreased free thyroxine (FT4) and thyroid stimulating hormone (TSH) in neonates, we assessed development by gender and maternal PCDD/Fs exposure at years 2 and 5 in 92 mother and newborn pairs. RIA quantified thyroid, sex, and growth hormones. Of 200 subjects followed up from November 2000, 136 and 149 were observed at year 2 and year 5, respectively. PCDD/Fs exposure levels were low (n = 35) or high (n = 35) in 70 subjects at year 2, low (n = 21) or high (n = 20) in 41 at year 5. Height, weight, BMI, and head circumference were significantly higher in males, chest girth significantly higher in females at year 2. Significantly, more girls had higher bone age (BA) and chronological age (CA) at both times. Height, weight, FT4 × TSH, and transthyretin (TTR) at year 2; and height, triiodothyronine, and IGF-1 at year 5 differed significantly by PCDD/Fs level. In females, height, weight, CA, BA, and thyroid hormones differed significantly at year 2. In males, FT4 × TSH at year 2 and IGF-1 at year 5 were significantly higher in the high PCDD/Fs group. In utero exposure to PCDD/Fs differentially affects growth and hormone levels in male and female preschool children.