Where's this contacts logging coming from?

When I run my app there's lots of logging in the console appearing, with it appearing with my app's name as the process.

My app is accessing contacts, however I'm not logging this, so is the OS?

The thing is, I'm testing performance with contacts databases which have thousands of entries in them, not only is this logging cluttering up the console making it difficult to examine, but I think the logging of so many thousands of line is affecting performance.

Where is it coming from? Can it be turned off?