A small note on Lead

We were talking about this in class, and I wanted to settle the issue of whether or not the Ancient Romans knew of the dangers of Lead and did anything to prevent poisoning. Flipping around in Hughes, I found the perfect passage, and Hughes claims that " Vitruvius knew that lead pipes could be dangerous"(p162). Because of these, Romans would apparently waterproof the inside of aqueducts with "maltha concrete, a pinkish mixture including lime, pork fat, and the milk of unripe figs" (p162). I searched on the web for the explanation of this, to say the least, interesting concoction and found nothing relevant. And as a closing note, to support the claim that Roman emperors may have had dementia due to lead poisoning, Wikipedia claims that Romans used lead acetate as a sweetener in their wines. So it seems to me that Romans did know of the dangers of lead and in some cases tried to counteract them, but ironically continued to directly ingest the substance. Natural selection at work?