稻米穀粒中銦及鎘的分布及其他元素(鈣、鈦、錳、銅、鋅、銣和鉬)含量

Abstract

半導體產業為台灣高度發展之工業，但限於台灣耕地有限，工廠及其排放水緊鄰農田之現象普遍。銦為半導體產業中會使用之元素之一，而鎘則曾在稻米中被檢測出來，且被認為可能是因土壤或灌溉水汙染所造成之累積現象。稻米(Oryza sativa)為人們重要的主食之一，近年來，因研究證據顯示穀物麩皮含有許多對人體有益之植化物(phytochemicals)及微量營養元素(micronutrients)，可以降低疾病的風險，而興起食用全穀的風潮，各國的人民營養指南亦鼓勵人民日常主食應以全穀為宜，包括糙米及有色米。因此，本研究擬進行稻米中危害元素：銦及鎘在稻米中各部位的分布與累積量進行探討，及稻米中巨量元素(鈣、錳、銅及鋅)與微量元素(鈦、銣及鉬)之含量探討。本研究共分三方面進行，第一部分乃共收集 27 個確知產地來源稻米樣品(包括：13 個稉稻、3 個秈稻及 11 個有色稻米)，進行其殼、糙米、麩皮及精白米之鎘及銦含量測定。第二部分則收集市售稻米樣品共 65 個，包含 31 個糙米、25 個有色米、及 9 個精白米，測定有色米、糙米及精白米(包含 31 個自行精白之糙米樣品)中之銦、鎘、鈣、錳、銅、鋅、鈦、銣及鉬含量。第三部分則以水耕栽培試驗在水稻植株開始抽穗後，添加不同濃度的銦(0.1、1 及 2 mg/L)以探討銦含量及水稻品種(台稉 9 號、台中秈糯 2 號及台中在來 1 號)對稻穀中銦含量與分布之影響。結果顯示，銦主要分布於麩皮，平均含量為 0.12 mg/kg，稻穀其他部位幾乎小於定量極限，且糙米與精白米樣品中，鎘含量平均皆低於臺灣的限量標準。市售稻米樣品分析結果顯示，糙米中鈣、鋅、錳、銣、銅和鉬的平均含量分別為 24.46、27.60、20.67、3.97、2.73 及 0.59 mg/kg，有色米中鈣、鋅、錳、銣、銅和鉬的平均含量分別為 38.26、30.33、20.94、5.45、2.86 及 0.64 mg/kg，銦含量在所有市售稻米樣品皆小於定量極限，鈦及鎘含量則是多數樣品小於定量極限。風險評估的結果顯示臺灣人藉由攝食米暴露到的鎘之非致癌性風險可以被忽略。水耕栽培試驗結果顯示，本試驗中銦濃度並未造成稻米穀粒中銦之累積，但似乎糯稻對銦的耐受性較差。本研究提供各元素在糙米與有色米的含量，可做為後續全榖類商品開發之依據。

The semiconductor industry in Taiwan is highly developed. Because of the limited cultivated lands in Taiwan, factories and their effluents are next to farmlands. Indium is one of the elements used in the semiconductor industry. Cadmium has been detected in rice and thought to be caused by polluted soil or irrigation water. Rice (Oryza sativa) is an important staple food. In recent years, studies have shown the bran of grains contains many phytochemicals and micronutrients, which have benefits to the humans and can reduce the risk of diseases. Thus, it is popular and encouraged by the dietary guideline to eat whole grains in daily life, including brown rice and colored rice. Therefore, this study investigated the distribution of toxic elements: In and Cd contents in different parts of rice grains and the contents of macronutrients (Ca, Mn, Cu and Zn) and micronutrients (Ti, Rb and Mo) in the rice.There were three parts in this study. In the first part, 27 location-specified rice samples (including 13 japonica, 3 indica and 11 colored rice) were analyzed the Cd and In contents of husk, brown rice, bran and polished rice. In the second part, 65 commercial rice samples were collected, including 31 brown rice, 25 colored rice and 9 polished rice, to be analyzed the contents of In, Cd, Ca, Mn, Cu, Zn, Ti, Rb and Mo in colored rice, brown rice and polished rice (including rice samples polished from 31 brown rice). In the third part, to investigate the influence of the contents of In and rice varieties (TK9, TCSW2 and TCN1) to the In contents in rice grains, different concentration of In (0.1,1 and 2 mg/L) were spiked when the rice plant started to ear. The results showed that In was mainly distributed in bran and the average contents were 0.12 mg/kg, and the other part of paddy were almost lower than LOQ. The average contents of Cd in brown rice and polished rice were all lower than the limitation in Taiwan. The results of commercial rice samples showed that the average contents of Ca, Zn, Mn, Rb, Cu and Mo in brown rice were 24.46, 27.60, 20.67, 3.97, 2.73 and 0.59 mg/kg, respectively. The average contents of Ca, Zn, Mn, Rb, Cu and Mo in colored rice were 38.26, 30.33, 20.94, 5.45, 2.86 and 0.64 mg/kg. The contents of In were lower than LOQ in all commercial rice samples. The contents of Ti and Cd were lower than LOQ in most commercial rice samples. The results of risk assessment showed that the non-carcinogenic risk of Cd exposure from rice intake of Taiwanese people can be ignored. The results of the hydroponic test showed the concentration of In in this study did not cause In to accumulate in rice grains. However, it seemed that TCSW2 had a lower tolerance to In.This study provides the contents of the elements in brown rice and colored rice and it can be the basis of whole grains product development.