Why 'Shielding' is recommended for underground physics?

Dear Experts,

I found that GEANT4 recommends Shielding physics list for underground physics application. I would highly appreciate it if you could let me know the reason(s) for this suggestion and also if there are articles available which describe this.

Thanks and regards,

Because underground physics is typical backgrounds limited, and involves lower energy background sources. The Shielding physics list includes NeutronHP, so you get better results for low-energy neutron interactions in your shielding and detector materials.