When purchasing a home in Oregon that was built prior to 1978, you will receive a Lead Based Paint Disclosure from the seller.  This document is a statement from the seller of their knowledge of the presence of lead based paint in the home.  You should also receive a Lead Based Paint in the Home pamphlet from your Realtor.  The EPA puts out a good one titled:  "Protect Your Family From Lead In Your Home". 

You may look at this document and wonder when looking at an older home if this issue is material to you.  This depends on your lifestyle.  If you have children or small pets, dust and peeling paint could be an issue.  If you are planning on doing a major remodel, the dust created could be made airborne in the home. 

To determine the presence of lead, you may elect to have a licensed environmental tester come out to the home and do some tests.  The inspector uses a hand-held x-ray to check for the fluorescence that lead gives off.  These results are recorded and downloaded into a report for you.  It is pretty common to find lead with this test.  The real worry here is whether or not the lead is out in the environment of the home.  You will want to have the inspector check around your water pipes and drains.  Another test that they will do is a dust test.  Dust is collected from a specific area and put into a collection jar.  These tests are then taken to the lab to be analysed.  In some instances, tests can be turned around in 24 hours.  A full HUD style test takes about 2 hours and is very thorough.