Asbestos found

[Vy Mai]

We found asbestos covering the pipes in the basement. I found it weird because the current owners has an 8 yrs old boy living there.  The sellers will rent from us for the next 7 months or until they find a place. My question is : 

1.  Do I have to write something in the lease contract so that I don't get sued?  What should I write to cover all ends?

2.  We will definitely have it removed once the sellers move out.  Do we still have to let the next renters know about the asbestos that existed before?