The risk factors and threshold level of subchronic inhalation exposure of reclaimed water  

作　　者：Jiayang Kong Yun Lu Yunru Ren Menghao Chen Gang Liu Liangliang Shi 

机构地区：[1]State Key Joint Laboratory of Environment Simulation and Pollution Control,State Environment Protection Key Laboratory of Microorganism Application and Risk Control,School of Environment,Tsinghua University,Beijing 100084,China

出　　处：《Journal of Environmental Sciences》2024年第3期639-650,共12页环境科学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (Nos.51738005 and 21777084)。

摘　　要：Inhalation of reclaimed water is known to cause lung infammation,and free endotoxins have been shown to be a major risk factor for acute exposure.Subchronic exposure has also been shown to induce infammatory responses with visible tissue damage.However,subchronic risk factors have yet to be identified,and a threshold for the protection of occupational populations during urban reuse is necessary.In this study,potential risk factors in reclaimed water were examined by subchronic exposure with fractionated reclaimed water,and the health risk threshold was tested with a series of diluted reclaimed water.Accordingly,following a 12-week exposure,macromolecules and microorganisms were found to be two major risk factors in reclaimed water that could cause pulmonary infammation,including increased proportion of polymorphonuclear leukocytes in bronchoalveolar fuid,formation of inducible bronchus-associated lymphoid tissue,and elevation of Immunoglobulin A levels.Moreover,infammation persisted after a 4-week recovery period.The calculated threshold of reclaimed water exposure for mice was 31.8 Endotoxin Unit(EU)/(kg·day)under when exposed to 50%additional relative humidity from reclaimed water at 25℃ for 2 hr/day.Meanwhile,the subchronic threshold estimate for humans under the same exposure conditions was found to be 12.2 EU/(kg·day),corresponding to endotoxin levels of 61.7 EU/mL in reclaimed water.The threshold level of endotoxin was lower than that in most non-potable reclaimed water.The findings of this study suggest that occupational exposure of reclaimed water can serve as a potential risk to workers.

关 键 词：Reclaimed water Inhalation exposure Risk factor THRESHOLD Infammation ENDOTOXIN 

分 类 号：X503[环境科学与工程—环境工程] X703