中国两大优势产区小麦重金属镉含量调查与膳食暴露评估

Survey and Dietary Exposure Assessment of Cadmium in Wheat from Two Main Wheat-Producing Regions in China

【目的】分析中国两大小麦优势产区小麦重金属镉的污染水平和特点,明确不同消费人群食用小麦引起的镉膳食暴露风险,以期为中国农产品质量安全监管提供科学依据。【方法】在中国黄淮海和长江中下游两大小麦优势产区的8个省(市)采集2013年收获的小麦样品393份,利用低温消解进行前处理,通过石墨炉原子吸收分光光度计测定全部小麦样品中镉浓度,分析不同区域不同品种小麦镉的含量差异。结合中国不同消费人群的小麦消费数据和体重信息,利用非参数概率方法对小麦镉的膳食暴露量进行评估。【结果】中国两大小麦优势产区的小麦镉含量均值为(0.032±0.051)mg·kg-1,97.5%的小麦样本镉含量低于国家限量要求。长江中下游优势产区的小麦镉含量均值为(0.060±0.091)mg·kg-1,黄淮海优势产区的小麦镉含量均值为(0.024±0.025)mg·kg-1,长江中下游小麦优势产区的小麦镉含量水平显著高于黄淮海小麦优势产区的小麦镉含量水平,不同品种、同一品种的小麦镉含量也存在一定的差异。中国不同消费人群对于小麦镉的膳食暴露风险不同,总体表现为:农村高于城市,低龄高于高龄,18岁以下的消费人群呈现女性高于男性,18岁以上的消费人群则呈现男性高于女性的特点。中国不同消费人群对于小麦镉的平均暴露量为国际食品添加剂联合专家委员会(JECFA)推荐的PTMI(暂定每月耐受摄入量:25μg·kg-1bw)的9.0%—16.8%,P97.5百分位数暴露量为PTMI的28.9%—53.8%,暴露量最高值出现在4—7岁女童,暴露量最低值出现在60—70岁女性。中国城市消费人群对于小麦镉的膳食暴露风险表现为:低龄高于高龄,男性高于女性,但60—70岁的城市消费人群中女性偏高于男性,并且城市女性消费人群中14—18岁和45—60岁两个年龄段的暴露量偏低,中国城市消费人群对于小麦镉的平均暴露量为PTMI的7.3%—13.1%,P97.5百分位数暴露量为PTMI的23.4%—42.2%,暴露量最高值出现在4—7岁男童,暴露量最低值出现在14—18岁女性。中国农村消费人群对于小麦镉的暴露量呈现与全国类似的规律,平均暴露量为PTMI的9.6%—17.9%,P97.5百分位数暴露量为PTMI的30.9%—57.4%,暴露量最高值出现在4—7岁女童,暴露量最低值出现在60—70岁女性。【结论】中国黄淮海小麦优势产区和长江中下游小麦优势产区的小麦受到的重金属镉污染程度较轻,区域间和品种间差异都较为明显。中国不同消费人群对于小麦镉的膳食暴露风险不同,食用这些区域生产的小麦引起的镉暴露量较低,且风险在可接受的水平。

【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（age1〈8 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.