A guy who knew I was familiar with lead abatement called me and said his 6-month-old son had tested positive for lead. I said, "you live in an old house, could he have eaten some paint? Answer, No we've scoured the house and no evidence of that. Everything was painted when we moved in, so the lead isn't on the surface. Turned out, he had done a little scrape-and-paint for a little old lady neighbor's porch and had brought it home on his clothes.
Lead is insidious and very dangerous for children. Adults not so much, but any exposure to an infant or child under about 12 can be very dangerous to the child's health.