Windows: Monitor Access to Environment Variables?

Question

Programs (on Windows) often expect certain environment variables to be set. However, the name of these environment variables is often not well documented. E.g.: Does Eclipse expect %MINGW_HOME% or %MINGW_DIR% or whatever? (This is just an example, there are more difficult cases.)

Therefore it would be handy to log every (successful and unsuccessful) access to environment variables, just like Process Monitor logs access to files.

Is there any tool to do so?

It should be possible if the target process uses GetEnvironmentVariable(), but it's probably not possible if GetEnvironmentStrings() is used...