Sugita M, Tsuchiya K
Department of Environmental and Occupational Health, Toho University School of Medicine, Tokyo, Japan.
Environ Res. 1995 Jan;68(1):31-7. doi: 10.1006/enrs.1995.1005.
For heavy metals, many experimental studies using animals have revealed short biological half-times (BHTs) to be 1 year or less by administration of heavy metals. Tsuchiya and Sugita, however, devised an original method and first reported the possibility of a long BHT for cadmium (Cd) calculated from Cd accumulation in postmortem human organs and tissues by age using a nonlinear regression analysis employing a differential equation. According to their reports, the estimated values of Cd BHT were 12.1-22.7 years in the kidney. The estimated Cd BHTs are point estimators. The point estimator of Cd BHT has been used indiscriminately to derive safety levels for Cd in the air of work environments or foodstuffs in the general population without taking into consideration individual variation of Cd BHT. In the present study, the estimated variation among individuals of Cd BHT ranges from a few years to at least 100 years in the kidney. It is concluded that the estimated average BHT according to mathematical calculation should not be used indiscriminately to derive the safety level of cadmium exposure.
对于重金属而言，许多使用动物的实验研究表明，通过施用重金属，其生物半衰期（BHTs）较短，为1年或更短。然而，土屋和杉田设计了一种原创方法，并首次报告了通过使用微分方程的非线性回归分析，根据死后人体器官和组织中镉（Cd）的积累随年龄变化情况来计算镉的长生物半衰期的可能性。根据他们的报告，肾脏中镉的生物半衰期估计值为12.1 - 22.7年。镉生物半衰期的估计值是点估计值。镉生物半衰期的点估计值在推导工作环境空气中镉或普通人群食品中镉的安全水平时被不加区分地使用，而没有考虑镉生物半衰期的个体差异。在本研究中，肾脏中镉生物半衰期的个体估计差异范围从几年到至少100年。得出的结论是，不应不加区分地使用根据数学计算得出的估计平均生物半衰期来推导镉暴露的安全水平。
