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目的估测环境镉接触致人群肾损伤的基准剂量(BMD),推出基准剂量的95%下限(BMDL),探讨镉的生物接触限值。方法选择甘肃省白银市某镉污染区居民为调查对象。以尿镉为人体镉负荷指标,以尿β2-微球蛋白和尿NAG酶为肾功能指标,应用BMD法对资料进行拟合与分析。结果随着体内镉接触水平的升高,Uβ2-MG和UNAG的异常发生率均明显升高,经趋势卡方检验,差异有统计学意义(P<0.01);选择Log-Logistic为最优模型计算尿镉BMD和BMDL,当以尿NAG为效应指标时,BMD/BMDL值为(6.46/5.21)μg/g·cr,以尿β2-MG为效应指标时,BMD/BMDL值为(3.16/2.26)μg/g·cr。结论在运用BMD法时应注意效应指标临界值的选取、剂量的设置以及最优模型的选择;建议以更为敏感的尿β2-MG为效应指标所计算的BMDL值为依据,适当降低尿镉的生物接触限值。
Objective To estimate the baseline dose (BMD) of kidney injury caused by cadmium exposure in the environment and to introduce a 95% lower limit of the baseline dose (BMDL) to explore the limits of bioavailability of cadmium. Methods The residents of a cadmium-contaminated area in Baiyin City of Gansu Province were selected as the survey subjects. Urinary cadmium as cadmium load indicators, urinary β2-microglobulin and urine NAG enzyme as renal function indicators, the application of BMD data fitting and analysis. Results The incidence of Uβ2-MG and UNAG increased significantly with the increase of exposure to cadmium in vivo. The chi-square test showed that the difference was statistically significant (P <0.01). Log-Logistic was the optimal model The BMD / BMDL values were (6.46 / 5.21) μg / g · cr when urinary NAG was used as indicators, and the urinary β2-MG index was (3.16 / 2.26) μg / g · cr. Conclusion BMD method should pay attention to the selection of the critical value of the effect index, the dose setting and the optimal model selection. It is recommended to use the more sensitive urinary β2-MG as the effect index to calculate the BMDL value based on the appropriate reduction of urine cadmium Biological exposure limits.