I might be mistaken here, but from what I've read on lead, we already know relatively well what amount of lead is safe, according to body weight etc. We also know that our bodies can deal with these small amounts, by actually getting rid of some of it. Maybe someone with more knowledge on the matter can chime in?
My understanding is that all detectable amounts currently have known negative effects when studied. The Action levels are set based on what is possible to address in an individual child.
Lead exists in the environment. It would be impractical to impossible to eliminate it entirely from the blood streams of most people. However certain areas have extremely dangerous concentrations such as dirt near major roads/old buildings, water in certain areas, and lead paints.
Lead pipes are an interesting one where it is simply impractical to replace all the pipes and remove lead in old cities. Hence as long as the calcification holds there is no action on the small amount of lead which leaks into the pipes.
Actually, you dont need to replace the pipes. They can actually line them in place. Of course then people might have concerns about the chemical makeup of the liners (basically plastic), but it's hard to say what other alternatives are out there.
That statement has the exact same problem. With sufficiently sensitive tests you might in theory be able to detect the negative effects of a single lead atom.
What we really want to know is: how big of a deal is this really?
There are unlikely to be people in the US with blood levels less than 1 order of magnitude less than the EPA action threshold. Lead is in your drinking water, food, and if you lived near anything with leaded - your air.
We used to use lead based pesticides at the dawn of the 20th century, if you eat any food grown in the midwest you are exposing yourself to reasonably large quantities of lead.
In the US at least, were it structured as an infrastructure project on a city by city basis, it would actually be extremely possible to strip out lead pipes and replace them with something modern.
The problem is that pipe ownership in a domestic home is the property of the homeowner, and there's no political will to do that kind of massive wealth transfer from the public coffers to the improved infrastructure of millions of individual properties. But while it wouldn't be inexpensive, it's on par with other expenditures the federal government makes for federal projects.
Total lead tells you your symptoms today. But it accrues so you'd need to know in advance your future lead intake to know if this small amount today will be a big impact tomorrow. Basically its unknowable so its practical to say that no amount is safe. There probably does exist a low enough level that the body can even clear it but there isn't any will to define it.
