A quick lesson in lead - It is more dangerous for children to be exposed to lead then adults as their bodys are still growing and more importantly there is at present no treatment for children with lead poisoning. There is what is called background levels present in all of us. Since lead was used in the past in such things as paint and gasoline for a very long time it is still present in old buildings and houses and in soils by the side of roads. It is also present in our blood at very low levels because of these exposures. An average of 6 micrograms of lead per deciliter of blood seems to be a norm. A microgram is equal to one grain of sugar. It had been thought that children could handle up to 10 micrograms with no ill effects and that has been a standard for some time. There are now some doubts about that 10 microgram figure.
So how to protect the young ones from lead? If you live in an older home (pre 1980's) you can assume that there is lead paint on the walls. You can also assume that the wallls have been painted since, but if the paint chips or peels there is a danger. Keep kids away from paint that's peeling if you are not sure. A simple text kit is a pen that will turn red or pink when touched to a lead painted object. It is just a rough guide and samples should be sent to a lab. Ask your local health dept. for more info on this as laws differ in dealing with this.
I'll discuss chromium and silica exposures in later entries.