工業原料中結晶型游離二氧化矽含量調查

Survey on Free Silica Content in Industrial Material

本研究主要針對市售礦物性粉狀原料之結晶型游離二氧化矽進行含量調查，結果發現工業用原料中仍以矽砂類、瓷土類及黏土類之結晶型游離二氧化矽含量較高，因此在使用該類物質之作業場所應特別注意環境之改善並使用適當之個人呼吸防護具。雖然結晶型游離二氧化矽在原料中之含量與作業環境空氣中粉塵含量有所差異，但若考量實施環境測定之方便性及經濟性、分析方法之準確性、認可實驗室之設備、以及考量作業現場實際狀況等，本研究建議以原料樣品中之結晶型游離二氧化矽含量配合秤重法來評估作業環境，應較為可行。綜合過去及本次之分析調查資料，部份市售原料標示含二氧化矽成份高達60%至80%，但經本研究分析後發現該等物質中結晶型游離二氧化矽之成份僅佔2%，顯然非屬於結晶型游離二氧化矽。由於造成人體矽肺症之主要原因來自結晶型游離二氧化矽，故本研究建議實施環境測定時不能以商品標示之SiO2含量為評估標準，建議可參考勞工委員會及本所之研究調查結果。另外，從本次分析結果發現，分析結晶型游離二氧化矽含量時，以紅外光譜法較易受雜質干擾，相對以X-光繞射分析時則干擾較小。故在經費或技術允許時，建議能使用X-光繞射分析，降低分析時可能造成的誤差。

This research studied crystalline free silica present in commercial powder-form mineral raw materials. The results showed that silica, kaolin and clay contained more crystalline free silica, and therefore any workplace using these materials should receive more attention in terms of environmental amelioration, and should require workers to wear proper protective masks. Although crystalline free silica contents in raw materials might be different from those in air samples taken at the work environment, considering convenience and cost of environmental monitoring, accuracy of analytical methods and equipment available in laboratories, the study suggested analysis of crystalline free silica content in raw materials, together with weighting methods, for industrial hygiene evaluation. Literature and data from this research showed that some brands contained as high as 60 to 80% silica, of which only 2% was in crystalline free form. Since crystalline free silica was the major cause of human silicosis, the study suggested that the content of silica indicated on product labels should not be used as the standard for workplace environmental monitoring. Instead, study results from the Council of Labor Affairs and the Institute of Occupational Safety and Health should be considered. Furthermore, this study demonstrated that for analysis of crystalline free silica content, infrared spectroscopy was more prone to interference from other substance than X-ray diffraction. As much as financially and technically possible, X-ray diffraction was recommended in order to reduce analytical errors.