Abstract: 【Objective】 The objective of this study is to analyze the variation and characteristics of cadmium levels in wheat of two main wheat-producing regions in China and assess the risk degree and law of cadmium in wheat from dietary exposure to different consumer groups. Results of this study could provide a scientific basis for the supervision of quality and safety of agro-products in China.【Method】 A total of 393 wheat samples were collected from two main wheat-producing regions of Huang-Huai-Hai and the middle and lower reaches of the Yangtze River, including 8 provinces (cities). The wheat samples were treated with nitric acid and hydrogen peroxide solution by low-temperature digestion. The cadmium contents of the samples were detected by graphite furnace atomic absorption spectrophotometer (GFAAS). A non-parameter probabilistic model was used to assess the dietary exposure risk based on the information of wheat consumption and body weight of target populations. 【Result】The mean of cadmium contents of wheat in China’s two main wheat-producing regions was (0.032±0.051) mg·kg^-1, and cadmium contents in 97.5% wheat samples were below maximum allowable concentration (MAC). The average content of cadmium in wheat was (0.060±0.091) mg·kg^-1 in the middle and lower reaches of Yangtze River region, while the level was (0.024±0.025) mg·kg^-1 in Huang-Huai-Hai region. The cadmium levels of wheat in the middle and lower reaches of Yangtze River region were significantly higher than those in Huang-Huai-Hai region. There were different cadmium concentrations of wheat between different planting regions. Also it showed difference in the same variety from area to area. Considering the disparity of age and the difference of city and countryside, generally, differences were found in dietary exposure among the various consumer groups all over the country. Different consumption groups with exposure levels of cadmium in wheat had an overweighed ranking for the groups of countryside, younger ages, respectively. Considering the disparity of gender, the exposure levels of cadmium in wheat in females were higher than the levels in males (age＜18 years old). When the age ＞18 years old, the opposite case presented. The percent ratio of the mean of the assessed dietary exposure value to PTMI recommended by JECFA (Joint FAO/WHO Expert Committee on Food Additives, Provisional tolerance monthly intake: 25 μg·kg^-1 bw) was in the range of 9.0%-16.8%, the 97.5th percentile level was from 28.9% to 53.8%. The highest exposure level occurred in girls of 4-7 years old, and the lowest was found in women of 60-70 years old. In the city, considering the disparity of age and gender, the different consumption groups with exposure levels of cadmium in wheat have an overweighed ranking for the groups of younger ages and masculinity, respectively. Although the exposure level of females was higher than those of males in the age of 60-70 years old and there were lower exposure levels in the age of 14-18 and 45-60 years old in females in the city. The percent ratio of the mean of the assessed dietary exposure value to PTMI was in the range of 7.3%-13.1%, the 97.5th percentile level was from 23.4% to 42.2%. The highest exposure level occurred in boys of 4-7 years old, and the lowest was found in women of 14-18 years old. The assessed dietary exposure level of rural consumer groups had the similar rules of all over the country, the exposure value in the countryside to PTMI was in the range of 9.6%-17.9%, and the 97.5th percentile level was from 30.9% to 57.4%. The highest exposure level appeared in girls of 4-7 years old, and the lowest was found in women of 60-70 years old. 【Conclusion】 The study showed that the cadmium pollution in wheat was at lower level. There were significant differences in cadmium contents of wheat among the areas and within the varieties. The differences were found in dietary exposure among the various consumer groups. The probability of health risk of cadmium via wheat exposure was at the acceptable level.

Key words: wheat, main wheat-producing regions, cadmium, dietary exposure