Comment by spawarotti

This situation reminds me of low-background steel:

Low-background steel, also known as pre-war steel, is any steel produced prior to the detonation of the first nuclear bombs in the 1940s and 1950s. Typically sourced from shipwrecks and other steel artifacts of this era, it is often used for modern particle detectors because more modern steel is contaminated with traces of nuclear fallout.

https://en.m.wikipedia.org/wiki/Low-background_steel