You can keep samples as long as you want. The CAP requires accredited labs to keep them 10 years. Attorneys simply want a record retention policy, which creates a natural tension many lab directors respond to by getting rid of the blocks after 10 years. See (1) for the checklist, the specific line item is ANP.12500. In theory things can get kicked to a biorepository, but the standards for a CAP-accredited biorepository are quite high. Running a biorepository that's not accredited raises the specter of questions like "What are you doing with this material, doctor?", so a lot of folks would rather burn our hope for the future than have any possible source of questions about what they're doing.
I see. I guess on the bright side collecting new data is becoming exponentially cheaper. For example, this year the world will collect more heart rate data than it did than all previous years in human history combined. So even if we lost all heart rate data from decades past, we generate that quite quickly now. You certainly lose a lot of longitudinal value, but perhaps that won’t turn out to be too critical? (Or perhaps it will)
(1) http://elss.cap.org/elss/ShowProperty?nodePath=/UCMCON/Contr...