The background levels of Cr and Ni generally ranged from 22.9 to 98.8 mg/kg and from 18.6 to 66.7 mg/kg respectively in the surface soils of rural lands in Taiwan.Twelve rice varieties were grown in two heavy metals(Cr and Ni)-contaminated soils of 8 regions of Taiwan in 2005,2006,2008,and 2010.However,high background levels of Cr and Ni in the rural soils derived from serpentinites corresponding to paddy rice was also investigated in 2010,2012,and 2013 in Eastern Taiwan.Under normal background concentration of soil,total Cr and Ni content <50 mg/kg,the Cr concentration of brown rice almost ranged from ND to 0.5 mg/kg,and those of Ni ranged from ND to 6 mg/kg.In this study,the results indicated that there is almost same Cr or Ni concentration(Cr ND-0.8 mg/kg and Ni ND-8 mg/kg)of brown rice grown at very high Cr-or Ni-contaminated soils ranged from 200 to 500 mg/kg(brown rice sample numbers,n= 2,300).The concentrations of Cr in the brown rice samples of the serpentinite soil,grown at high Cr and Ni concentration of soils ranged from 200 to 1,000 mg/kg(Cr)or 100-2,000 mg/kg(Ni),were lower than 1.5 mg/kg,and those of Ni were lower than 4.5 mg/kg(n=67).The field studies conducted in the Cr-and Ni-contaminated soils and high levels of Cr and Ni in serpentinitic soils indicated that there is almost same Cr or Ni concentration of brown rice as listed above.The relationship between Cr and Ni content of brown rice and soil total concentration by aqua regia or 0.1 N HCl extraction soil Cr or Ni concentration(n=2,300)meet the "plateau theory".In Taiwan,the average total intake of brown rice is near 150 grams per person per day.Because the regulation of food standards of Cr and Ni are not available in the world and the Cr and Ni concentrations of brown rice were in the range of edible crops and foodstuff of the world,the tolerable upper intake level calculated results of Cr and Ni of brown rice are under acceptable value.We concluded that the total intake of Cr or Ni of brown rice even grown at the soil concentration of Cr(<600 mg/kg)and Ni(<1,500 mg/kg)can be evaluated as safety level and almost no risk(less than 1 of one million)after health risk assessment.