renter worried about lead based paint

[Roy Mitle]

I am renting out to a couple with a baby. the house is ~40 years old so earlier than 1978 in california.

We are required to provide lead paint disclosure. Everyone just says they are not aware (ie no one ever tested it). thats what our seller did and thats what i did to renter.

now renter is worried that lead paint can cause health issue for kid. she wants to get it tested. my realtor says that u will always get a result as positive. however, since this has been painted multiple times over it shouldn't matter unless the paint is peeling. 

Any ideas how to get out of this logjam?