Extremely exciting topic...I know. But I recently ran into this issue. Our single family home was built in 1971. According to Maryland's Lead Risk Reduction in Housing Act which was passed during the 2012 legislative session, as of 1/1/2015, all residential rental properties constructed prior to 1978 must be registered and renewed annually. On or after 1/1/2015, all properties built prior to 1978 must have a new lead inspection certificate at each change of occupancy.
I know what you're thinking, I have to get my rental home inspected every time a new tenant comes in? That's $200-400 a pop! BUT, currently residential rental properties built after 1949 and properties that have a passing Lead Free inspection certificate are EXEMPT! Meaning, instead of getting a lead inspection, get a Lead FREE inspection (technicalities). This shows there is no sign of Lead in the home and can be transferable with the home once it's time to sell! Sure, it'll probably run you about $500-700 but it's a one time expense!
Also, in case you think you can dodge this whole lead registration thing, say your renters have kids. In Montgomery County, the MoCo School requires a Lead inspection or Lead Free Certificate in order to enroll the student.