半導體金屬對V79中國頰鼠肺細胞之細胞遺傳毒性的研究

隨著人類文明的進步，半導體成品已和人類生活息息相關，所以近年來半導體工業得快速發展。半導體產品因使用目的不同而成分會有所不同，其中□（In）、銻（Sb）、鎵（Ga）、鍺（Ge）均被使用於晶片中。半導體工業表面上看起來相當安靜且安全，但其晶片在製造過程需使用許多有害的化學物質，如管理不善將危及現場操作人員的健康和污染環境，因此半導體從業人員可能因工作環境之不良而增加曝露這些半導體金屬的機會，但半導體金屬成分對人類細胞或其他哺乳動物細胞之細胞毒性及遺傳毒性除砷被大量研究並確認為人類致癌物和銻稍被研究外其餘尚少被研究。　　本研究利用微小核法（MN）來探討半導體金屬成分，□（In）、銻（Sb）、鎵（Ga）、鍺（Ge）在V79中國頰鼠肺細胞（V79 Chinese hamster lung cells）之細胞遺傳毒性並觀察這些金屬間的交互作用及對細胞型態之影響，另外藉由D-Penicillmine (D-PA)，Dimercaprol (BAL), SOD和Catalase 的加入來觀察是否會降低半導體金屬所產生的遺傳毒性，以探討半導體金屬致細胞遺傳毒性的機轉是否和蛋白質硫氫基（Sulfhydryl）之抑制和／或氧自由基（ROS）之形成有關？亦探討D-PA和BAL當半導體金屬中毒之解毒劑的可能性。　　細胞毒性之研究結果發現在Cyt-B存在下Ga, Sb, In抑制V79肺細胞存活率之作用可被加強，其中以Sb的抑制最為明顯，相較之下In只稍微但具統計意義地抑制V79肺細胞之存活率。在Cyt-B不存在下，只Ga和Sb抑制V79肺細胞之存活率，而Ge不管Cyt-B是否存在均不影響V79肺細胞之存活率。在細胞型態之觀察中發現Ga 及Sb會改變V79肺細胞之細胞型態。由於Cyt-B已知可影響細胞骨架之形成而降低細胞存活率，所以推測Cyt-B可能是加強Ga和Sb對細胞骨架之傷害而造成V79肺細胞存活率下降。　　關於遺傳毒性方面，Sb和In在0.01-3μM之濃度範圍中劑量－相關性地增加V79中國頰鼠肺細胞之微小核數，但Ge(3-300μM)和Ga(1-100μM)均不嘖呈現有統計意義的遺傳毒性。交互遺傳毒性之探討發現Ge可對抗Sb和In之遺傳毒性，Ga則加強Sb之遺傳毒性，但Ga對In則無此作用。此外，Sb(0.03-0.1μM)和In(0.03-0.01μM)並不會相互加強遺傳毒性，由此顯示半導體金屬間之交互遺傳毒性相當複雜。　　拮抗劑之研究結果顯示，SOD及Catalase可減少In 及Sb所增加V79肺細胞之微小核數，而低濃度(l-3μM)的BAL亦可降低In(0.3μM)及Sb(0.3μM)所增加的微小核數。lμM D-PA可降低 In(0.3μM)所增加之微小核數，但對Sb(0.3μM)則無此對抗作用。綜合上述的結果，Sb和In之遺傳毒性可被SOD，Catalase，低濃度的BAL及D-PA所緩解，所以推測Sb和In其致遺傳毒性的作用可能和自由基之形式及含硫氫基酵素受抑制有關，且Sb和In之遺傳毒性可被Ge降低但其機轉尚未清楚，故Sb和In造成遺傳毒性之機轉為多方面而非單一機轉所能解釋。 由於Sb和In在相當低濃度(≧0.1μM)便具遺傳毒性，此和大多數致突變性金屬相當不同（需10μM-10m M)。所以對半導體工業之暴露工人可能相當具危險性。Ge和Ga雖不具遺傳毒性，但a具細胞毒性且有報告指出Ge和Ga在人類有腎毒性，在懷孕之頰鼠造成畸形胎，在職業工人或實驗動物造成肺氣腫和呼吸道疾病，所以亦不能忽視其對半導體工人之危險性。

The semiconductor industry has experienced rapid growth since its origin 46 years ago with the invention of the transistor. Semiconductor manufacturing is a chemically intensive industry involving many potentially hazardous materials such as organic solvents, strong acids, strong caustics, metals, reactive gases, and dopants. There are a large number of intermetallic compounds from group Ⅲ-group V that have been made and could be used in semiconductor devices, circuit chips and other components used in the electronics industry. These compounds not only include binary compound, but also could include ternary and higher compounds of these of elements. Workers in semiconductor industry exposed to the reactants and products of the group Ⅲ-V intermetallics when the apparatus used in the processes are opened to add materials or remove products. There is also exposure when large crystals are cut into smaller wafers with diamond-bladed saws. There wafers are also washed, lapped and polished during the preparation process. It showed be noted that the genotoxic effects of those intermetallic compounds. Although the metalloid arsenic (As) has been studied is detail, while information on genotoxic effects of Ge, Ga, In, Sb and other intermetallics in cultured mammalian cells is not enough available.　　In the present study, the frequency of micronuclei (MN) and trypan blue exclusion were assayed to evaluate the cytogenotoxic effects of semiconductor metals (Ge, Ga, In, and Sb) in V79 Chinese hamster lung cells (V79 lung cells). The effects of semiconductor metals on cellular morphology and viability of V79 lung cells were conducted with or without 3μg/ml cytochalasin B(Cyt-B). The frequency of MN was also assayed to explore the genotoxic interactions among the four semiconductor metals. In order to shed more light of the mechanism of semiconductor-induced genotoxicity and antidotes for semiconductor metal poisoning, we investigated the effects of D-penicillamine (D-PA), dimercaprol (BAL), superoxide dismutase (SOD), and catalase on semiconductor-induced genotoxicity as qualified as by MN.　　Without Cyt-B, both Ga and Sb significantly decreased the viability of V79 lung cells as compared with control. However, Cyt-B potentiated the inhibitory effects of Ga, In and Sb on viability of V79 lung cells. Ge didn''t affect the viability of V79 lung cells with or without Cyt-B. On the other hand, both Ga and Sb markedly affected the cellular morphology of V79 lung cells. Cyt-B is known to interfere cytoshkeletal formation, and then induce cytotoxicity. Accordingly, we tentatively assumed that Cyt-B might potentiate the inhibitory effects of Ga and Sb on cytosheletal formation of V79 lung cells and then caused more severe cytotoxicity.　　Among the four semiconductor metals, both In and Sb at concentrations of 0.01-3μM significanity increased MN frequency in a concentration-dependent manner in V79 lung cells, but both Ge(3-300μM) and Ga(1-100μM) didn''t induce any significant genotoxicity. In the periodic table of the elements, both antimony and arsenic belong the same GrVA elements, and a chemico-toxicological similarity to arsenic is often found when referring to antimony and its toxicology. Accordingly, antimony is suspected to be a carcinogen although it is not clear whether antimony is carcinogenic to man. To our knowledge, there are no reports about In-induced genotxcicity in mammalian calls, we first found that In induced genotoxicity in V79 lung cells. In addition, Ge attenuated genotoxic effects of Sb and In. Ga potentiated Sb-induced genotoxicity, but did not affect In induced genotoxicity. However, the genotoxic interactions between Sb and In didn''t appear significant difference. Obviously, the genotoxic interactions among those semiconductor metals are very complication.　　All concentrations of SOD and catalase tested alone did not induce genotoxicity, but BAL and D-PA at higher concentrations (BAL≧10μM; D-PA≧3μM) tested alone induced significant genotoxicity. However, both SOD and catalase significantly inhibited the genotoxic effects of In and Sb. Similarly, BAL at lower concentrations of 1-3μM produced the antigenotoxic effects. On the other hand, 1μM D-PA only attenuated the genotoxic effect of In. The results appear the mechanism of the genotoxicity of In and Sb are party attributed to be their reaction with SH moieties in the molecules and oxygen radical production. In this study, Ge also attenuated the genotoxic effects of In and Sb by undetailed mechanisms. These findings show that the mechanism of the genotoxicity of In and Sb might be complex and not based on a single mechanism.　　Both In and Sb caused pneumoconiosis and pulmonary fibrosis following long-term exposure in workers. In this study, both In and Sb were effective in inducing genotoxicity at very low concentrations (≧0.1μM) in V79 lung cells. Accordingly, both In and Sb may be especially hazardous to the workers who exposure to the semiconductor process environment. On the other hand, both Ge and Ga didn''t cause significant genotoxic effects in this study or other reports. However, some authors reported that both Ge and Ga caused nephrotoxicity in human, and induced teratogenesis in pregnant hamster. We can''t neglect the risk of semiconductor workers who exposed to Ge and Ga.