Search

Background: Growing studies have focused on the effects of ambient air pollution on thyroid hormones (THs), but the results were controversial. Therefore, a systematic review and meta-analysis was conducted by pooling current evidence on this association., Methods: Four databases were searched for studies examining the associations of particulate matter [diameter ≤10 μm (PM 10 ) or ≤2.5 μm (PM 2.5 )] and gaseous [sulfur dioxide (SO 2 ), nitrogen dioxide (NO 2 ), ozone (O 3 ), carbon monoxide (CO)] pollutants with THs levels. Random effects models were used to pool the changes in THs levels with increasing air pollutant concentrations. Subgroup analyses were constructed by region, design, sample size, pollutant concentrations, evaluated methods, and potential risk exposure windows., Results: A total of 14 studies covering 357,226 participants were included in this meta-analysis. The pooled results showed significant associations of exposure to PM 2.5 , PM 10 , NO 2 , SO 2 , and CO with decreases in free thyroxine (FT4) with percent changes (PC) ranging from -0.593 % to -3.925 %. PM 2.5 , NO 2 , and CO were negatively associated with levels of FT4/FT3 (PC: from -0.604 % to -2.975 %). In addition, results showed significant associations of PM 2.5 with hypothyroxinemia and high thyroid-stimulating hormone (TSH). Subgroup analyses indicated that PM 2.5 and NO 2 were significantly associated with FT4 in studies of Chinese, and similar significant findings were found in studies of PM 2.5 and FT4/FT3 in areas with higher concentrations of air pollutants and larger samples. PM 2.5 exposure in the first trimester was found to be associated with lower FT4 levels in pregnant women., Conclusion: Our findings suggest that exposure to air pollution is associated with changes in THs levels. Enhanced management of highly polluted areas, identification of harmful components and sources of PM, and protection from harmful exposures in early pregnancy may be of great public health importance for the population's thyroid function., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Particulate matter (PM) exposure increased the risk of hospital admission and was related to symptoms of schizophrenia (SCZ). However, there are limited studies on the relationship between PM exposure and SCZ relapse risk, and the underlying biological mechanisms remain unclear. We designed an air purification intervention study under a 16-day real air purifier scenario and another 16-day sham air purifier scenario, with a 2-day washout period. Twenty-four chronic stable male patients were recruited. The oxidative stress biomarkers were measured including serum catalase (CAT), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), malondialdehyde (MDA), and nitric oxide (NO). The relapse risk was evaluated by the early signs scale (ESS). Linear mixed effect models were fitted to establish the associations between PM exposure and ESS and oxidative stress. Mediation model was performed to explore the mediation effect of oxidative stress on the PM-ESS association. Higher concentrations of PM 2.5 /PM 10 exposure were associated with an elevated risk of relapse of SCZ. For each 10 μg/m 3 in PM 2.5 concentration, the scores of ESS and subscales of incipient psychosis (ESS-IP), depression/withdrawal (ESS-N), anxiety/agitation (ESS-A), and excitability/disinhibition (ESS-D) were increased by 4.112 (95% CI: 3.174, 5.050), 1.516 (95%CI: 1.178, 1.853), 1.143 (95%CI: 0.598, 1.689), 1.176 (95%CI: 0.727, 1.625) and 0.238 (95%CI: 0.013, 0.464), while logCAT, SOD and T-AOC were reduced by 0.039 U/ml (95% CI: 0.017, 0.060), 1.258 U/ml (95% CI: 0.541, 1.975), and 0.076 mmol/l (95% CI: 0.026, 0.126). In addition, pathways of "PM 2.5 →T-AOC→ESS-A″ and "PM 2.5 →T-AOC→ESS-D″ were found, with significant T-AOC mediated effects 15.70% (P = 0.02) and 52.99% (P = 0.04). Our findings suggest that PM may increase the risk of anxiety, depression, excitability, and incipient psychosis behaviors in SCZ patients, while reducing the function of the antioxidant system. The decrease of T-AOC may medicate the PM-ESS association in SCZ., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Air pollution may alter the composition of gut microbiome and subsequent liver-related metabolic disorders. Schizophrenia was often accompanied by liver dysfunction. But it was still unclear whether air pollutants affected liver function in patients with schizophrenia through gut microbiome. We aimed to clarify the impacts of long-term air pollutants on the gut microbiome and liver function in schizophrenia and to evaluate the intermediary effect of microbiome. Schizophrenia patients were recruited then serum biochemical indicators were tested. Air pollutant exposure in the previous year was retrospectively estimated by inverse distance weighting. The associations among air pollutants, gut microbiome, and liver function indicators in schizophrenia were estimated. Then the mediating effect of gut microbiome was further explored. The results showed that nitrogen dioxide (NO 2 ), carbonic oxide (CO), ozone (O 3 ), particulate matter with aerodynamic diameter ≤10 μm (PM 10 ), and fine particulate matter (PM 2.5 ) explained 2.68%-10.77% of the variation in gut microbiome composition (order level) in schizophrenia (all P < 0.05). Network correlation analysis indicated that air pollutants and liver function indicators were mainly related to Firmicutes, Actinobacteria, and Proteobacteria in schizophrenia. Long-term NO 2 exposure significantly increased the levels of gamma-glutamyl transpeptidase (GGT) and glutamic pyruvic transaminase (GPT) in schizophrenia. Coriobacteriales mediated 13.98% and 49.56% (all P < 0.05) of the associations of long-term NO 2 with GGT and GPT, respectively. To conclude, long-term NO 2 exposure is positively associated with liver dysfunction in schizophrenia, in which gut microbiome plays an intermediary role. The two pathways, "NO 2 -Coriobacteriales-GGT" and "NO 2 -Coriobacteriales-GPT", would provide scientific evidence for the intervention of schizophrenia with liver dysfunction., (Copyright © 2021 Elsevier Ltd. All rights reserved.)