Toxic Effects Of Typical Odorous Methylamine Pollutant Exposure On Human Respiratory System

With the rapid development of economy and industry in China,as well as the acceleration of urbanization and the improvement of people’s quality of life,the problem of odorous pollutants in atmospheric environment has attracted more and more attention.Odorous pollutants have low odor threshold and high toxicity.They are a potential nuisance to the environment and public health.Previous researches showed that long-term exposure to the malodorous gas would aggravate the symptoms of people with asthma or allergies,leading to the loss of olfactory function and digestion.In addition,the pollutants could lead to the disorders of the respiratory and endocrine,and poison the nervous system of human beings.In recent years,more and more scholars have focused on the control and treatment of odorous pollutants.Nevertheless,the research on the effects of odorous pollutants on human health is very limit.Previous studies have shown that volatile organic compounds(VOCs)with high concentration could cause considerable adverse effects on the respiratory system.Nevertheless,the effects of the odorous pollutants at environmentally relevant levels to the people’s health are still lack.Therefore,more detailed research design is needed in the future,with a focus on their toxic effects.Among the malodorous VOCs,methylamine is the simplest organic amine pollutant.It has a wide range of applications and high emission rate,but there are few related studies.Therefore,in this thesis,the human bronchial epithelial cells 16 HBE were exposured under different concentrations(0,6.44,12.88,19.32,25.76,32.20,38.64 m M)and different time points(12 and 24 h)of malodorous VOCs methylamine aqueous solution.The cytotoxicity was studied from the aspects of cell activity,damage of cell membrane,intracellular reactive oxygen species(ROSs)level,enzyme activity level and inflammatory reaction.Furthermore,the animal pathology experiments were also carried out to explain the toxic effects of methylamine on the respiratory tract of rat.The results showed that the stimulation concentration of methylamine had a significant effect on the cytotoxicity of 16 HBE.The higher the concentration of methylamine,the greater the corresponding cytotoxicity,the more serious the damage of cell membrane,and the lower the cell viability,which were dose dependent.Furthermore,the results also showed that methylamine could affect the expression of cytokines related genes,including p53,STAT3,Bcl2,c-myc,Cyclin D,Hes1,Mcl-1,and TGF-β2.The breakdown of those cell proliferation and apoptosis related genes could lead to a common toxic mechanism of cell death.Studies on the level of antioxidant enzymes in cells found that methylamine stimulation could affect the ability of scavenging oxygen free radicals in cells,and that methylamine also has a greater effect on intracellular ROS levels.The ratio of mean fluorescence intensity between methylamine-stimulated and blank groups up to 30 times,the average fluorescence intensity ratio in the mitochondria is also 8 times.After the addition of antioxidants in the system,the effect of methylamine stimulation on cell viability is weakened,and the fluorescence intensity of intracellular ROS is also significantly reduced.In the study of the induction of intracellular inflammatory factors by methylamine,it was found that methylamine stimulation could lead to the up-regulation of inflammatory factors including interleukin-6(IL-6),interleukin-8(IL-8),tumor necrosis factor-α(TNF-α),and affect the expression of nuclear factor-kappa B(NF-κB)protein.NF-κB signaling pathway.The animal pathology experiment directly reflected the significant changes in alveolar structure changes,cell wall hyperplasia,and tissue cell shedding in the lungs of rats after methylamine stimulation.This study demonstrates that the odorous methylamine has a significant toxic effect on the respiratory tract,revealing that methylamine can induce oxidative stress and shows potential inflammatory effects in human airway cells after inhalation of methylamine,which is methylamine to human bronchial epithelial cells.The toxicity and animal pathology studies provide scientific data.