Exposure to multiple metals and leukocyte telomere length in children and adolescents: The mediating effect of thyroid hormones

• Published in: Environmental research 2025-01, Vol.265, p.120483, Article 120483
• Main Authors: Liu, Qing, Fan, Gaojie, Bi, Jianing, Fang, Qing, Luo, Fei, Huang, Xiaofeng, Li, Heng, Liu, Binghai, Yan, Lianyan, Guo, Wenwen, Hu, Liqin, Mei, Surong, Wang, Youjie, Song, Lulu
• Format: Article
• Language: English
• Subjects: Adolescent; Child; Children and adolescents; China; Cross-Sectional Studies; Environmental Exposure - adverse effects; Environmental Pollutants - toxicity; Environmental Pollutants - urine; Female; Healthy lifestyle; Humans; Leukocytes - drug effects; Leukocytes - metabolism; Male; Metals - blood; Metals - toxicity; Metals - urine; Telomere - drug effects; Telomere length; Thyroid hormones; Thyroid Hormones - blood; Urinary metals
• ISSN: 0013-9351; 1096-0953; 1096-0953
• DOI: 10.1016/j.envres.2024.120483

Exposure to metals has been related to alterations in leukocyte telomere length (LTL), an aging marker. However, the evidence regarding this relationship in children and adolescents, as well as the underlying mechanisms, remains unclear. Therefore, we aimed to explore the individual and mixture effects of metals on LTL in children and adolescents and to assess the mediating role of thyroid hormones and the modifying effect of a healthy lifestyle. In a cross-sectional study performed in Liuzhou, China, we assessed 5 serum thyroid hormones, 18 urinary metals, and LTL among 1050 children and adolescents aged 6–18 years. We employed multivariate linear regression and weighted quantile sum (WQS) regression to assess the associations of urinary metals with LTL in children and adolescents. Mediation analyses were conducted to explore the effects of thyroid hormones on these relationships. Urinary cobalt (Co), nickel (Ni), strontium (Sr), mercury (Hg), cadmium (Cd), and thallium (Tl) were related to a shorter LTL in children and adolescents. The WQS regression showed a 6.31% (95% CI: −8.76%, −3.79%) decrease in LTL per quartile increase in the WQS index, and identified Ni (23.3%), Sr (21.7%), and Tl (18.0%) as the major contributors. Mediation analyses showed that triiodothyronine (T3) mediated 14.8% and 8.1% of the associations of urinary Sr and Hg with LTL, respectively, and suppressed 9.3% of the association with urinary Co. Furthermore, the inverse associations of Sr, Cd, and Tl with LTL were attenuated among participants who adopted a healthy lifestyle. Our findings suggested that exposure to Co, Ni, Sr, Cd, Hg, Tl, and their mixture were related to a shorter LTL in children and adolescents, potentially mediated by thyroid hormones. Additionally, adopting a healthy lifestyle may alleviate these adverse effects. [Display omitted] •Urinary Co, Ni, Sr, Cd, Hg, and Tl were negatively related to LTL.•Metal mixture was negatively associated with LTL.•Thyroid hormone partially mediated the association between metals and LTL.•Adopting a healthy lifestyle helps attenuate the adverse effects of metals on LTL.