We can't detect below part per trillion today.

我们今天无法检测到密度低于万亿分之一的物质。

So we're finding effects at parts per trillion concentrations.

所以我们发现了万亿分之一浓度的影响。

One part per trillion, just to give you a flavor of the scope, it is a single drop of water in an Olympic-sized swimming pool.

万亿分之一——给你一个概念范围：它就像奥运会泳池中的一滴水。

So a part per trillion is basically a sneeze in the span of human civilization, but it's these sneezes, these parts per trillion at that concentration that is concerning for health professionals.

所以万亿分之一基本上是人类文明跨度中的一个喷嚏，但正是这些喷嚏， 这些万亿分之一的浓度让卫生专业人员感到担忧。