Effects of high fluoride and iodine combined exposure on thyroid nodules and goiter in school-age children in Jiangsu, China.

Introduction: With advancements in detection equipment and an increase in the frequency of examinations, thyroid nodules and goiter in children have garnered attention.

Objective: This study aims to determine the effects of high iodine and fluoride exposure on thyroid nodules and goiter in school-aged children.

Methods: We recruited children aged 8 to 12 from rural Jiangsu, China, based on the concentrations of iodine and fluoride in local drinking water and urine. Participants were divided into four groups: a group with high fluoride and iodine (HFHI), a group with high fluoride (HF), a group with high iodine (HI), and a control group (CONTROL). Fluoride levels in both drinking water and urine samples were measured using the ion-selective electrode method. Urinary iodine (UI) was assessed using inductively coupled plasma mass spectrometry, and children's thyroids were examined with portable ultrasound equipment equipped with a linear 7.5-MHz probe.

Results: The detection rates of thyroid nodules in the HFHI, HF, HI, and CONTROL groups were 10.4 %, 6.5 %, 7.7 %, and 2.8 %, respectively. The goiter detection rates were 3.8 %, 2.9 %, 3.8 %, and 1.1 %, respectively. In the HFHI group, statistically significant correlations were found between urinary fluoride (UF) and thyroid nodules (P = 0.011, adjusted OR and 95 % CIs were 2.29 [1.21, 4.32]), as well as between UI and thyroid nodules (P = 0.038, adjusted OR and 95 % CIs were 1.58 [1.04, 2.40]), and between UI and goiter (P = 0.014, adjusted OR and 95 % CI were 2.31 [1.19, 4.48]). In the HI group, there was a statistically significant link between UI and goiter (P = 0.005, adjusted OR and 95 % CI were 2.45 [1.31, 4.58]).

Conclusions: Combined high iodine and fluoride exposure may have an adverse effect on thyroid nodules in school-age children.