- 學位論文
氫氧化四甲基銨局部經皮吸收大白鼠動物毒性試驗
Toxicity evaluation of transdermal absorption of tetramethylammonium hydroxide (TMAH) in the rat model
摘要
背景 : 氫氧化四甲基銨是一種腐蝕性的鹼性溶液。氫氧化四甲基銨已被廣泛使用在半導體產業, 光電產業和核磁共振的顯影劑製程中。在2007年2月16日, 高雄地區兩名工廠操作員被氫氧化四甲基銨噴濺皮膚後不幸於二日內死亡。氫氧化四甲基銨的主要結構四甲基銨(TMA)為弱的乙醯膽鹼脂酶的抑制劑，但個案之乙醯膽鹼脂酶之濃度並未下降。TMA最先會影響快速活動的肌肉(如:眼球､手指的肌肉)，接著是四肢､軀幹､頸部的肌肉，最後才會癱瘓肋間肌與橫隔膜。呼吸衰竭似乎是致死的主因，但是真正的中毒致死機轉並不明確。 材料與方法:本次研究採動物實驗模式，以皮膚暴露25%和2.38%兩種濃度的TMAH，測量各項生理學參數、皮膚敏感性測試、致死劑量和嘗試可能的解毒劑。使用體重300~350公克的Sprague-Dawley雄性大白鼠，以剃刀剃除老鼠背部毛髮後，以皮下注射與皮膚塗抹的方式測量致死劑量。以血壓、呼吸監測器，測量不同時間點之生理數值。以串聯式液相層析質譜儀 (LC/MS/MS)的方法分析不同時間點，血清中TMA的濃度。以免疫比濁法測量血液中乙醯膽鹼酶的濃度。皮膚敏感性測試，根據Draize(1959)皮膚反應分類標準，觀察暴露TMAH 4小時候的皮膚顏色變化。關於解毒劑測試方面，以atropine為主要測試藥劑。 結果:經由皮膚暴露於2.38%和25% TMAH的大白鼠，其LD50分別為89.75 mg/kg、34.17 mg/kg。其95%信賴區間分別為53.20-111.43 mg/kg、20.73-54.05 mg/kg。經由皮下注射TMAH的LD50為14.26 mg/kg ，其95%信賴區間為9.16 - 20.51 mg/kg。在病理與皮膚組織切片，可以看到雖然在TMAH不同的濃度的暴露下，隨著暴露時間的增加，對於皮膚組織的傷害有著決定性的影響。在皮膚暴露於TMAH 六十分鐘後，其在血液內的TMA 濃度達到最大濃度。各組間血液中乙醯膽鹼酶的濃度，隨著皮膚暴露氫氧化四甲基銨的濃度與時間增加，有逐漸下降的趨勢，但各組間乙醯膽鹼酶的濃度未達統計上顯著差異。TMAH確實可以經由皮膚吸收，以TMA原型的狀態存在於血液之中。在皮膚暴露於TMAH的大白鼠，可觀察到有抽搐與漸進性呼吸衰竭的情形。 結論:呼吸衰竭仍是TMAH致死的主因。TMAH確實可以經由皮膚吸收，並以TMA原型的狀態存在於血清之。TMAH的毒性無法以血液中TMA與乙醯膽鹼酶的濃度，完整解釋呼吸次數的變化。是否可能合併一些神經性之傷害，仍待進一步的研究。
並列摘要
Background : TMAH (tetramethylammonium hydroxide) is a kind of corrosive alkaline solution. It was widely used in manufacturing process in semiconductor industry, photoelectronic industry and MRI contrast agent. However, two operators died after exposed to TMAH without proper personal protection within 2 days in Kaohsiung on February 16, 2007. The main structure of TMAH is TMA (tetramethylammonium ion) which is a weak inhibitor of acetylcholinesterase. In these two mortality cases after exposed to TMAH, no obvious decreasing concentration of acetylcholinesterase were found in their blood samples. TMA can affect these small, rapidly moving muscles such as those of the fingers and eyes first, and those of the limbs, neck and trunk are involved later. The intercostal muscles and the diaphragm are the last to be paralyzed. Respiratory depression seems the most possible reason to cause death, but the real mechanism of toxicity is still unclear. Material & Methods : We established the animal mode for the skin exposure of 2.38 % and 25% TMAH and the physiologic parameters were recorded. Skin irritation test, lethal dose, and possible antidotes were also performed. The Sprague-Dawley male rats’ (weight 300-350 g) dorsal hairs were shaved, and the lethal dosage of THAH was measured by subcutaneous injection and daubing TMAH on the skin. The physiological parameters were recorded at different time points by the blood pressure and breath monitors. The measurement of TMA concentration in the plasma was analyzed by the LC/MS/MS. The concentration of blood acetylcholinesterase was measured by immunoturbidimetric method. According to the criteria of Draize (1959) for classification of skin reaction, the change of skin color after the exposure of TMAH for 4 hours was used as an index of the skin irritation test. Atropine was tested as an antidote. Results: The LD50 of TMAH after skin exposure to 2.38% and 25%, is 89.75 mg/kg、34.17 mg/kg respectively. The 95% confidence intervals of LD50 is 53.20-111.43 mg/kg and 20.73-54.05 mg/kg respectively. The LD50 of TMAH after intra-peritoneal injection is 14.26 mg/kg and the 95% confidence intervals of LD50 is 9.16 - 20.51 mg/kg. After skin exposure to TMAH for 60 minutes, the blood concentration of TMA reached the peak level. The blood concentration of cholinesterase of each group decreased with time, but there was no obviously different within each group. TMAH could exist in the plasma in a prototype through skin absorption. Microscopically, it showed the skin damage progressed with time and concentration of TMAH. Progressing dyspnea following with respiratory failure and convulsion-like movement were observed after skin exposure to TMAH. Conclusions: Respiratory depression is the main cause of death after exposure to TMAH. TMAH could exist in the plasma in a prototype through skin absorption. However, the inhibition of respiratory function is not totally connected to the concentration of TMA and cholinesterase. Other possible neurologic toxicity may be considered. Further study is necessary.