The problem with looking at things this way is that there is no discussion of amounts and dose-dependent effects. The article just says "For lead there's no 'too low'". and "we want zero." Fine enough, but as we are very good at measuring ever-smaller quantities of things we will find all manner of out-of-place chemicals that we have been tolerating just fine. I'm sure I have measurable amounts of arsenic, lead, aluminum, chlorine, radioactivity, etc in my body right now, in levels that do not have a meaningful impact on my health.

The real question we should ask is whether there is substantial evidence of a negative health impact from the levels of lead that are measured.

We should want to know exactly what levels were measured in these kids and be able to plot it out. We should have some idea of the health impacts of various doses. With that we could come to more meaningful conclusions.