Since maybe half a year ago, the best way to search stuff like that, by a huge margin, are frontier models like ChatGPT or Gemini. Here's what they found, the TLDR is that lead is much less likely to be essential (in extremely minute amounts) than arsenic, which has been proven to be beneficial in trace amounts for a bunch of mammals. Since those experiments cannot be done on humans, we don't know if it is the same situation in our case, but the null hypothesis at this point is that it is.

https://chatgpt.com/share/6a0d522f-5688-83eb-b80c-0f7b157fae... https://gemini.google.com/share/e2e52489a41e