Cadmium contamination of the soil in Fuyang Valley,Zhejiang Province and Cd uptake by rice were studied, and critical values for Cd in soils deduced based on Cd risk of rice consumption.Results show that high concentrations of Cd in soil and rice grains were detected in the study area.A model is established for prediction of Cd concentration in rice grains based on multi-factor regression analysis,taking into account soil total Cd and pH.With the aid of the model,critical values of Cd in different soil pH were derived,being 0.42 mg kg^-1,0.79 mg kg^-1,1.49 mg kg^-1 and 2.81 mg kg^-1 for soils with pH at 5, 6,7 and 8,respectively.Due to the spatial heterogeneity of soil pH in the study area,a high spatial variability was observed of critical values of Cd in soil.The results indicated that total Cd content in soil exceeded their critical values in 73% of the sampling sites.Therefore,sound strategies for risk management should be implemented to protect human health.In addition,uncertainties in deduction of soil Cd critical values come mainly from the risk assessment model and rice grain Cd uptake model and soil pH is the most sensitive parameter.