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Placental microplastics contamination and its impact on thyroid function in newborns

Ecotoxicology and Environmental Safety 2025 3 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Xuan Zhang, Li Li, Li Li, Yue Zhang, Bing‐Ying Liu, Xiaoyan Wang, Lei Sun, Lei Sun

Summary

Researchers analyzed placental tissue from over 1,200 mother-child pairs and found microplastics present in the samples, then examined whether these levels were associated with thyroid hormone profiles in the newborns. The study found associations between placental microplastic contamination and variations in newborn thyroid function, which is critical for early growth and development. These findings suggest that prenatal microplastic exposure warrants further investigation as a potential factor in infant health.

Microplastics (MPs), which have been identified in human tissues such as the placenta, may pose potential risks to newborn health by interfering with thyroid function, a critical regulator of growth and development. This study investigates the association between placental microplastic levels and thyroid hormone profiles in newborns. We investigated the effect of placental microplastic exposure on fetal thyroid hormone levels in a cohort of 1250 mother-child pairs enrolled between 2022 and 2024. Umbilical cord blood thyroid hormone concentrations (free thyroxine [T4], free triiodothyronine [T3], and thyroid-stimulating hormone [TSH]) were measured, and placental microplastics (PVC, PP, and PBS) were quantified. Multivariable regression models (MLR), quantile g-computation (g-comp) and Bayesian Kernel Machine Regression (BKMR) were used to assess the effects of microplastics on thyroid hormone levels, adjusted for relevant covariates. Adjusted MLR models confirmed that individual microplastic types, including PVC, PP, and PBS, were significantly associated with reductions in T4 levels (β = -1.40, -0.74, and -0.85, respectively) and TSH levels (β = -1.27, -2.87, and -1.94, respectively), as well as decreases in the T4/T3 ratio (β = -5.60, and -2.68 for PVC and PP, respectively). PP exposure was the only microplastic type associated with an increase in T3 levels (β = 0.05; 95 % CI: 0.01, 0.10; p = 0.03). G-comp analysis showed that each quartile increases in exposure corresponded to significant decreases in T4 (β = -1.78; 95 % CI: -2.38, -1.18), TSH (β = -3.72; 95 % CI: -4.71, -2.72), and the T4/T3 ratio (β = -6.24; 95 % CI: -8.53, -3.94; p < 0.01 for all). BKMR analysis further revealed a dose-response relationship, with higher microplastic exposure linked to decreasing T4 levels and a lower T4/T3 ratio, while T3 and TSH exhibited only minimal changes across exposure quantiles. This study reveals that placental microplastic exposure is linked to reductions in newborn thyroid hormone levels, particularly T4 and the T4/T3 ratio, with dose-response effects observed across exposure quantiles.

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