The biggest problems with lead paint are not the chips, but the dust. Those most susceptible are children under the age of five because of the way it affects their neurological development. Older houses are constantly shedding paint dust inside and out. Inside, daily vacuuming and mopping can mitigate the problem. Outside, the lead accumulates in the dirt surrounding the house. Infants and toddlers, for unknown reasons, spend an inordinate amount of their time crawling around (Why can't they walk like adults?). The dust gets on their hands and their hands go in their mouths. All that said, however, the biggest problems are likely to be caused by dirt in public parks and school playgrounds, rather than dust in the house. The reason is simple. Both tend to be located near highways and the primary source of environmental lead remains that which is left over from the days of leaded gasoline. The best thing we have done to reduce lead caused brain damage was to remove the lead from gas.
and lead dust??? yes, it is a problem - but mostly for the reason i stated above - sanding and remodeling, not so sure it is from the manner you describe. most lead paint has been painted over one or many times, so it is only a danger if it is sanded, peels and chips or a kid chews on a painted banister. lead paint 3 layers deep cant magically shed its dust through 2 layers of non lead paint.
The amount of mercury in those light bulbs is probably less than the amount in fish that you may be eating at any given time. I have broken and know many who have as well broken the backlights of monitors while taking them out to replace and we are all just fine
Among the things found in investigating cases where children developed dangerous levels of blood lead was that the primary source of lead dust in the homes came from dirt tracked into the houses from outside rather than from lead paint on the walls. To some extent that pattern was undoubtedly a NYC phenomenon that traces back to the work of Robert Moses.
Moses was the architect of the City's highway and bridge systems. A by-product of his work in building elevated roadways was the development of many schools, playgrounds and parks underneath and next to those same roads. Tests conducted in those parks and roads found that lead levels in the dirt were so high that the dirt was classified as hazardous waste. That lead came from two sources: leaded gasoline, and paint dust from repainting the roads. Unfortunately, the lead left behind is not volatile, and never leaves the soil until the soil has been removed.
You are right that LBP in normal buildings is most likely to be released during construction projects. That is why the law requires that such projects be performed by qualified staff with appropriate containment. However, the dust released during such projects -- even when performed by unqualified workers without containment -- is seldom the cause of elevated blood lead in children.