Chronic exposure to non-eruptive volcanic activity as cause of bronchiolar histomorphological alteration and inflammation in mice

It is estimated that 10% of the worldwide population lives in the vicinity of an active volcano. However, volcanogenic air pollution studies are still outnumbered when compared with anthropogenic air pollution studies, representing an unknown risk to human populations inhabiting volcanic areas worldwide. This study was carried out in the Azorean archipelago of Portugal, in areas with active non-eruptive volcanism. The hydrothermal emissions within the volcanic complex of Furnas (Sao Miguel Island) are responsible for the emission of nearly 1000 tons of CO2 per day, along with H2S, the radioactive gas - radon, among others. Besides the gaseous emissions, metals (e.g., Hg, Cd, Al, Ni) and particulate matter are also released into the environment. We test the hypothesis that chronic exposure to volcanogenic air pollution alters the histomorphology of the bronchioles and terminal bronchioles, using the house mouse, Mus musculus, as bioindicator species. Mus musculus were live-captured at three different locations: two villages with active volcanism and a village without any type of volcanic activity (reference site). The histomorphology of the bronchioles (diameter, epithelium thickness, smooth muscle layer thickness, submucosa thickness and the histological evaluation of the peribronchiolar inflammation) and of the terminal bronchioles (epithelium thickness and classification) were evaluated. Mice chronically exposed to volcanogenic air pollution presented bronchioles with increased epithelial thickness, increased smooth muscle layer, increased submucosa thickness and increased peribronchiolar inflammation. Similarly, terminal bronchioles presented structural alterations consistent with bron-chodysplasia. For the first time we demonstrate that chronic exposure to non-eruptive volcanically active environments causes inflammation and histomorphological alterations in mice lower airways consistent with asthma and chronic bronchitis. These results reveal that chronic exposure to non-eruptive volcanic activity represents a risk factor that can affect the health of the respiratory system of humans inhabiting hydrothermal areas. (C) 2019 Published by Elsevier Ltd.

据估计，全球10%的人口生活在活火山附近。然而，与人为空气污染研究相比，火山成因的空气污染研究数量仍然较少，这对居住在全球火山地区的人群构成了未知的风险。本研究在葡萄牙的亚速尔群岛进行，该地区存在活跃的非喷发性火山活动。弗纳斯火山群（圣米格尔岛）内的热液排放每天释放近1000吨二氧化碳，以及硫化氢、放射性气体——氡等。除了气体排放外，金属（如汞、镉、铝、镍）和颗粒物也被释放到环境中。我们以小家鼠（Mus musculus）作为生物指示物种，检验长期暴露于火山成因的空气污染会改变细支气管和终末细支气管组织形态这一假设。在三个不同地点活捉小家鼠：两个有活跃火山活动的村庄和一个没有任何火山活动的村庄（对照点）。对细支气管（直径、上皮厚度、平滑肌层厚度、黏膜下层厚度以及细支气管周围炎症的组织学评估）和终末细支气管（上皮厚度和分类）的组织形态进行了评估。长期暴露于火山成因空气污染的小鼠，其细支气管表现出上皮厚度增加、平滑肌层增厚、黏膜下层厚度增加以及细支气管周围炎症加重。同样，终末细支气管也出现了与支气管发育不良一致的结构改变。我们首次证明，长期暴露于非喷发性火山活跃环境会导致小鼠下呼吸道出现炎症和组织形态改变，与哮喘和慢性支气管炎相符。这些结果表明，长期暴露于非喷发性火山活动是一个风险因素，可能会影响居住在热液地区的人类呼吸系统健康。（C）2019由爱思唯尔有限公司出版