Arsenic expsoure assessment in semicondutor industry comparison with adminstration group

1. Arsenic expsoure assessment in semicondutor industry comparison with adminstration group Jefferin Tsao ,Yaw-Huei Hwang Institution of Occupational Medicine and Industrial Hygiene, College of Public Health, Nation Taiwan University, Taiwan Background Arsenic is a ubiquitous element in the environment. Inorganic arsenic is a documented human carcinogen, which is known the risk cancer of the skin, lung, urinary bladder and kidney. In semiconductor industry, inorganic arsenic is frequently used as a dopant material that are accelerated down a beam path and precisely implanted into the wafer. During the maintenance process, arsenic-containing by-products, such as arsenic trioxide, are deposited on surfaces inside the reaction chamber are the hazardous substances for maintenance engineer. Otherwise, maintenance area is opening space for engineer and technical assistors. Objective The objective of this study is to assess exposure risk of equipment engineer group in ion-implanter environment of semiconductor manufacture industry. Method and Material Inorganic arsenic is methylated in the body by alternating reduction of pentavalent arsenic to trivalent and addition of a methyl group from S-adenosylmethionine. Absorbed arsenate (AsV) is fairly rapidly reduced in blood to AsIII, which implies increased toxicity. Also, intermediate reduced forms of the methylated metabolites, trivalent of monomethylarsonic acid (MMAIII) and dimethylarsinic acid (DMAIII), have been detected in human urine. In particular MMAIII is highly toxic. To what extent MMAIII and DMAIII contribute to the observed toxicity following exposure to inorganic arsenic remains to be elucidated. Arsenic levels in urine is biomarkers for short-term (<1 year) and long-term (many years) internal dose. In this study, the rate of MMA/DMA (Rate 1) and MMA/Total Arsenic(Rate 2) were chosen as biomarker indexes to assess exposure profile. 108 equipment engineer of Ion implanter and 37 administrators of purchase department were recruited from 2004 to 2005, excluding 27 person whose MMA is higher than DMA. Table 1. Arsenic species contents in exposure and reference group Results Reference group is older and more senior than exposure group. MMA trended up twice from 2004 to 2005, but DMA slightly decreased. The difference of total As between two group was higher in 2005 than 2004. Rate 1 of exposure group was higher than reference group in 2004. Table 2 indicated exposure group of AsIII, MMA and Rate1 was higher than reference group as 0.013, 0.598 and 0.59 respectively after adjust with age, duration and age*duration, but not significant level. MMA and Rate1 grew up with age and duration. Conclusion and Discussion In this study, we observed rate1 is a positive index to compare exposure. According to Chen et al, prevalent rate of skin cancer and bladder cancer was significantly higher based on rate1 over 0.2 or 0.21. In semiconductor industry, engineer were asked to have good personal protection equipment wearing to reduce exposure. Minor exposure was probability under metabolism limitation. The concentration of total urinary inorganic arsenic metabolites might be misleading due to the confounding effect resulting from intake of seafood, such as arsenosuger. In such cases, monitoring of urinary arsenic species by using rate1 in total urinary inorganic arsenic metabolites as an indicator for the verification of arsenic exposure is helpful and appropriate Table 2. Linear regression analysis of age- and duration- factors with arsenic species in 2004