Lead is an additive that was put into better quality paints. Research discovered that the body treats lead the same way it treats calcium. It takes it through the blood and stores it in the bones. When the bones have high levels of lead, the blood it produces has a very difficult time carrying oxygen from the lungs to the other parts of the body, most notably the brain. This oxygen deficiency can have damaging results ranging from hyperactivity to permanent brain damage. The people most effected by lead poisoning are small children whose bones have a great need for calcium. Lead can break down into incredibly tiny particles. For example, the particles can fly right through a vacuum cleaner bag and into the carpet when you vacuum. These tiny particles can get on the hands of toddlers and then get ingested as they put their hands and their toys in their mouths. A frequent source of lead dust particles in the home are old windows with lead paint. Lead has not been used residentially since 1978. Any home built prior to 1978 should be tested for lead. If you are planning extensive remodeling of a home, it is a good idea to have the XRF test performed so prior to removing wall and wood work, you will know if there is lead present and be prepared to have it professionally removed. Although small children are most frequently effected by lead, it can effect anyone, at any age. If you are buying an older home, this test is highly recommended. If the home was an expensive home when it was built, the chances of lead in the home are extremely high.