Distribution of elements and their correlation in bran, polished rice, and whole grain.

The relationship of toxic elements (As, Cd, Cr) and trace elements (Cu, Se, Ni, Zn, Mn) in rice bran and corresponding polished rice is not well known. A total of 446 rice grains were collected from paddy fields distributed across China, and the concentrations of 8 elements in rice bran and their corresponding polished rice were measured. The levels of As, Cd, Cr, and Se have a good linear relationship between rice bran and polished rice ( : .79, .97, .82, .99, respectively; all  < .001). Polishing rice could effectively remove the average contents of 44.4% As, 19.8% Cd, and 15.4% Cr in the whole grain, but caused the substantial losses of more than half of Mn and Ni (57.7% and 56.9%), and nearly one-third (30.9%, 31.5%, and 29.1%) of Cu, Se, and Zn in brown rice although only about 10% of rice bran was milled. The "L" type correlation exists not only between As and Cd, but also between the nutrients Se, Mn, Ni, and the toxic elements As, Cd. These results indicated that As accumulation in rice could reduce the levels of essential mineral nutrients Mn, Ni, and Se. On the contrary, improving nutrient elements by fertilization could decrease the accumulation of some toxic elements. This provides a practical new idea for the prevention and control of rice As or Cd, and concomitantly improves the deficiency of nutrient elements in rice.