Problems with lead: it's toxic and it accumulates, lead doesn't leave you and builds up over time. It's not just toxic in the sense that too much will kill you, but even small quantities can cause nerve and brain damage, among other things. It is easier for your body to absorb lead than many other elements.

My comment was pointing out that despite lead being known for millennia as a problem in people, it was used for:

* water delivery pipes * plates and cutlery and cups * a paint ingredient in everyone's home * a sealant * a fuel additive that was spewed into the air by every motor vehical * a lubricant in a lot of machinery * a common additive to many additional products all over the place * a common additive in industrial processes leaving lead residue on products that wouldn't otherwise contain lead.

So the phrase: "underpins most of the technology in the world" somewhat realistically applies to lead - in the early 1900s it was everywhere all the time.

And as i pointed out at the start of this - it is kind of a bad choice to be using all the time in everything since it causes so many problems for people. Humanity has been dramatically reducing the use of lead in everything for a long time now (decades) and will continue to do so for a long time. The bad effects of all the lead use during the industrialization of our species will remain for quite a while.

So my whole point was: just because something was used in the creation of great outcomes, it doesn't make it any good in a fundamental way. I'm saying C is like lead in my analogy.