Environmental pollution by Cd has become one of the major health issues or problems in Japan. For example, "Itai-Itai (Ouch-Ouch)" disease was caused mainly by consumption of rice and drinking water that was contaminated with Cd derived from a river basin. On the basis of investigations on Cd levels in rice, which is the main Cd source for the Japanese, the following legal critical values have been set for Cd in rice: "have been set" implies that considerations other than scientific aspects have been taken into account.
(1) The surveillance level of Cd in unpolished rice is 0.4 μg/g.
(2) The maximum permissible level of Cd in unpolished rice is 1.0 μg/g.
It has therefore been required to accurately determine a range of concentrations of Cd and other heavy metals in unpolished rice and NIES has recently undertaken the development of "Rice Flour-Unpolished" for use primarily in the validation of analytical methods and in the calibration of analytical instruments covering 3 orders of magnitude of Cd levels.
These reference materials were each prepared in an identical manner from unpolished rice collected from three different locations in Japan. The unpolished rice was pulverized with a rotor speed-mill, sieved to pass a 0.5 mm screen, blended and bottled. The Rice Flour-Unpolished reference material is available in a set of three bottles (60 g each) from NIES.
Certified values are provided for Ca, Cd, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Rb and Zn, while reference values are reported for Al, As, Br, Cl, Co, Cr, Hg, Se and Sr. The elemental compositions (except Cd) in the three unpolished rice flour samples are very similar and are considered typical of Japanese unpolished rice.
Keywords: Biological material, Plant material, Foodstuff, Agricultural food product, Trace elements, Heavy metals