Spherical indentation of polycrystalline cubic boron nitride (PcBN): Contact damage evolution with increasing load and microstructural effects

In vivo, in vitro, and epidemiological evidence suggests that perfluoroalkyl substances (PFAS) may alter thyroid function in human health, with negative effects on maternal and fetal development outcomes. However, data on the effects of PFAS on thyroid hormones remain controversial. Here, we conducted a meta-analysis of 13 eligible studies searched from Embase, PubMed, and Web of Science by July 10, 2022, to explore the relationship between maternal exposure to PFAS and thyroid health effects, including thyroid stimulating hormone (TSH), triiodothyronine (TT3), thyroxin (TT4), free T3 (FT3), and free T4 (FT4). The estimated values (beta) and the corresponding confidence intervals (95%CI) were extracted for analysis. The tests for heterogeneity, sensitivity and publication bias between studies were performed using Stata 15.0. The combined results showed a positive association between changes in TSH and exposure to perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorodecanoic acid (PFDA), with no significant correlation observed between changes in other thyroid hormones and exposure to PFAS. This difference was attributed to sample size, region, sample type, body mass index (BMI), and gestational week. Our data recommend verifying the relationship between PFAS exposure and thyroid health effects in a large sample population cohort in future studies. In addition, health care should be taken into account in early and mid-pregnancy.

Automated summary

In vivo, in vitro, and epidemiological evidence suggest that perfluoroalkyl substances (PFAS) may affect thyroid function in human health, particularly during maternal and fetal development. However, there is controversy regarding the impact of PFAS on thyroid hormones. Through a meta-analysis of 13 studies, this research found a positive association between changes in thyroid stimulating hormone (TSH) and exposure to specific PFAS, while no significant correlation was observed for other thyroid hormones. The differences may be attributed to factors such as sample size, region, sample type, body mass index, and gestational week.