You can also just test children's blood. That is much more direct and would catch the problem whether it's the paint at home, the water, the paint at grandma's house, etc...

The problem is cumulative, so if you're testing everyone early you greatly limit the damage.

Massachusetts mandates that every child is tested for lead in the blood between 8 and 12 months of age, then at 2 years and at 3 years. Every pediatrician does the tests automatically at the normal checkups. And our rates of lead poisoning are much better than most other states with old houses.