As with all things, its complicated.

The romans knew that those who worked in lead mines or were lead smiths suffered tons of problems and died early because of their occupation.

The dangers of lead were never a mystery.

But they also knew that it takes more than simply touching lead to get sick. So they knew their lead pipes were fine since it was a low pressure gravity system unlike our modern system that is pressurized. Lead pipes in a pressurized environment actually mixes with the lead and causes problems.

And water logistics are NECESSARY to keep a city like Rome alive. So lead smiths were needed because lead is CRAZY USEFUL for all things precise and plumbing related.

But, lead also famously has a sweet smell when formed into lead acetate. And romans love sweet wines. So they'd boil down grapes and berries in lead pots to make a lead acetate sweetener. This theyd mix with wines to enhance them. Something they generally knew was bad but who knows. I like to think of it as the ancient roman equivalent of smoking. Yes objectively bad, but sometimes you need an extra sweet wine to take the edge off.

I'll give you better sources later. I think I got this from Mary Beards "SPQR" which is a must read. Not chronological, but fuck chronology. Where my thematics gang at!