Yes, it is not cumulative. One particle can start the cancer that will eventually kill you. The older the asbestos gets, the more it degrades. Its danger is directly related to how much it can and has degraded. This is called "friability" as Motts alluded. Basically the hard asbestos such as that found in siding or floor tiles is not as dangerous as that found in soft ceiling tiles and the wraps around old pipes. The old lath and plaster construction and some drywall will have a certain percentage asbestos also. These places are extremely dangerous. One can't assume that since thousands of people once worked and lived here and didn't get cancer that you won't get cancer. The asbestos was new then and was not degraded. Now it is old and the friable stuff is very degraded in many locations. The more exposure to the elements it receives, the more degraded it usually is. Steer clear or at least research and heed that research as Motts says.
The ownership of the files is what is in play. Who or what entity actually "owns" the files? The hospital itself owns them so where do you take them? The files that are still in use are transferred with patients and any file left is a copy and not needed-so it is property of the hospital. Doctors make copies of files for themselves as needed or wanted and they are taken with them to their own practices or home offices as the case may be OR they are abandoned too along with the hospital/institution files. Basically confidentiality of files such as these just depends on how much power you've got. Anything can be for your eyes if you have enough money or pull. You can see for yourself how confidentiality is treated. lol~sarcastic