There is evidence that polycyclic aromatic hydrocarbons (PAHs) and human gut microbiota are associated with the modulation of endocrine signaling pathways. Independently, studies have found associations between air pollution, land cover and commensal microbiota. We are the first to estimate the interaction between land cover categories associated with air pollution or purification, PAH levels and endocrine signaling predicted from gut metagenome among urban and rural populations.

The study participants were elderly people (65–79 years); 30 lived in rural and 32 in urban areas. Semi-Permeable Membrane devices were utilized to measure air PAH concentrations as they simulate the process of bioconcentration in the fatty tissues. Land cover categories were estimated using CORINE database and geographic information system. Functional orthologues for peroxisome proliferator-activated receptor (PPAR) pathway in endocrine system were analyzed from gut bacterial metagenome with Kyoto Encyclopaedia of Genes and Genomes.

High coverage of broad-leaved and mixed forests around the homes were associated with decreased PAH levels in ambient air, while gut functional orthologues for PPAR pathway increased along with these forest types. The difference between urban and rural PAH concentrations was not notable. However, some rural measurements were higher than the urban average, which was due to the use of heavy equipment on active farms.

The provision of air purification by forests might be an important determining factor in the context of endocrine disruption potential of PAHs. Particularly broad-leaved forests around homes may reduce PAH levels in ambient air and balance pollution-induced disturbances within commensal gut microbiota.

有证据表明，多环芳香烃（PAHs）和人体肠道菌群与内分泌信号通路的调节有关。独立地，研究发现空气污染，土地覆盖和共生微生物群之间存在关联。我们是第一个估计与空气污染或净化有关的土地覆盖类别，PAH水平和城市和农村人口肠道内基因组预测的内分泌信号之间相互作用的方法。

研究对象为老年人（65-79岁）；农村有30人，城市有32人。半渗透膜设备可用于测量空气中PAH的浓度，因为它们模拟了脂肪组织中生物富集的过程。使用CORINE数据库和地理信息系统估算了土地覆盖类别。利用《京都议定书》的基因和基因组百科全书，从肠道细菌的基因组分析内分泌系统中过氧化物酶体增殖物激活受体（PPAR）途径的功能直向同源物。

房屋周围阔叶混交林的高覆盖率与周围空气中PAH含量的降低有关，而PPAR途径的肠道功能直系同源物随着这些森林类型的增加而增加。城乡PAH浓度之间的差异是显着的。但是，由于农村活跃农场使用重型设备，一些农村地区的测量结果高于城市平均水平。

在多环芳烃的内分泌破坏潜力方面，森林提供空气净化可能是一个重要的决定因素。房屋周围特别阔叶的森林可能会降低环境空气中的PAH含量，并平衡共生肠道菌群内污染引起的干扰。