| 摘要: | 近年來奈米科技的盛行下，奈米材料廣泛應用於許多領域，因奈米物質大量的供給與需求，導致勞工暴露於奈米物質的潛在風險提高，因此奈米物質所衍生的職業健康危害需要被重視，而傳統產業中廣泛應用的電焊作業，也會產生有害的金屬燻煙以及奈米微粒，其中鋅在奈米樣本中含量是最高，所以應關注鋅元素在奈米粒徑下，所引起的職業健康不良效應。
本研究以微孔均勻沉積衝擊器對職場環境中電焊作業產生之奈米金屬微粒進行環境採樣，透過場發射掃描式電子顯微鏡(Field Emission-Scanning Electron Microscopy, FE-SEM)、能量散射X射線微分析(Energy Dispersive X-ray, EDX）、Zetasizer動態光散射儀等儀器，分析環境採樣後濾紙樣本以及奈米氧化鋅溶液中的奈米微粒之物理化學特性。為了驗證奈米氧化鋅微粒所造成的健康效應，本研究以動物模式透過氣管注射之暴露方法，探討單次暴露奈米氧化鋅微粒後，追蹤24小時(急性健康效應)和28天(亞慢性健康效應)後所導致的不良健康效應，像是發炎反應、氧化壓力、蛋白質表現、病理變化以及重要標的器官等分析。本研究進一步探討小鼠在暴露奈米氧化鋅微粒前施打抗氧化劑(N-acetylcysteine, NAC)，NAC是否能在24小時後能有效抑制肺部發炎及氧化壓力等反應之致病機轉。
本研究結果顯示實驗動物暴露不同劑量的奈米氧化鋅微粒，在24小時後發現實驗動物有急性發炎反應，另外，在暴露低劑量的奈米氧化鋅微粒，給予NAC可以提高抗氧化能力，降低發炎指標(總蛋白質、IL-6、LDH)，在高劑量組則是可抑制Caspase-3的活化，故NAC可能可以降低奈米氧化鋅微粒對肺部所引起的毒性作用。本研究並沒有發現奈米氧化鋅會對實驗動物造成亞慢性發炎反應。
With the recent development of nanotechnology, the application of nano-sized materials has been adapted for use in various fields. On account of the supply and demand of nano-sized materials, the latent dangers of exposure to these materials among workers has increased. Therefore, the health hazards associated with nano-materials has become a topic of importance. In more traditional production, the wide-spread use of welding also engenders the production of deleterious metallic fumes and nano-particles which contain a high concentration of zinc. Thus, efforts should be focused on investigating the zinc containing nano-sized particles and their deleterious effects on industrial hygiene.
In the present study, Micro-Orifice Uniform Deposit Impactor (MOUDI) was used to sample environmental metallic nano-particles produced from welding activities at worksites. ZnONPs will be characterized for their physicochemistry using scanning electron microscopes and energy dispersive X-ray analysis, dynamic light scattering and zeta potential. To provide evidence for the deleterious effect of zinc nano-particles, this study made use of an animal model. BALB/c mice were exposed to ZnONPs via intratracheal instillation. Mice were euthanized after 24 hours (acute exposure) and 28-days exposure (chronic exposure). Total protein, lactate dehydrogenase, inflammatory cytokines were determined in bronchoalveolar lavage fluid (BALF). 8-hydroxy-2’-deoxyguanosine (8-OHdG) and caspase-3 were determined in lung samples. The lung pathology was also investigated. Alteration in zinc in organs was determined. Furthermore, this study investigated BALB/c mice exposed to ZnONPs after injection N-acetylcysteine, and if NAC can effectively inhibit lung inflammation and oxidative stress after 24 hours.
Our results indicate that 24 hours after being to exposed to different doses of ZnONP, BALB/c mice had acute inflammatory reactions. Moreover, exposed to small doses of ZnONP, the NAC can increase antioxidant ability and lower inflammatory markers (Total protein, IL-6, LDH). High doses of NAC can inhibit Caspase-3 activity, since NAC may be able to lower the toxicity of oxidized zinc nano-particles with regard to pulmonary tissue. This study also failed to detect any chronic effect of oxidized zinc nano-particles in the animal model used. |
