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

Qing Liu, Gaojie Fan, Jianing Bi, Qing Fang, Fei Luo, Xiaofeng Huang, Heng Li, Binghai Liu, Lianyan Yan, Wenwen Guo, Liqin Hu, Surong Mei, Youjie Wang, Lulu Song

Department of Maternal and Child Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China; Key Laboratory of Environment and Health, Ministry of Education, And State Key Laboratory of Environmental Health (incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China. · pubmed

Paper

Abstract

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.

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Research summary

The paper investigates the relationship between metal exposure and leukocyte telomere length (LTL) in children and adolescents, linking environmental factors to a biological marker of aging. While it contributes to understanding how environmental toxins may influence aging processes, the findings are primarily observational and do not directly address interventions or mechanisms that could mitigate aging itself. Thus, while it is relevant to longevity research, its impact is limited and more incremental than transformative.

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