It has thus been demonstrated that a tiered approach at all three steps can be helpful to optimize the use of the available resources ; if relatively crude tools ? designed to provide a “ worst case ” estimate ? do not suggest a toxicologically significant exposure ( or a relevant deficit of a particular nutrient ) it may not be necessary to use more sophisticated tools 已经证明，在所有的三个步骤中一种分层的方法能够有效优化可用资源：如果一种相对粗糙的方法设计用来对最坏的情况进行评估没有显示有毒理学意义的暴露（或者某种特定营养的不足）那就不需要再使用更精确的方法。
