It's not my place to provide evidence, as I'm not the one making a positive assertion. It'd be nice if someone has done formal research on lead levels in electronics workers, but I've never seen anything like that posted, just a lot of scaremongering and ill-informed legislation.
Edit: you do realize what the term elemental lead refers to, correct? Here's another complex multi-syllable word that's worth of study by HN moderators: bioavailability.
Of course, it's much easier to downvote than to explain the apparent logical dissonance at work.