Elemental Impurities for Topical Solutions

I was wondering if anyone is testing “topical” solutions for elemental impurities. the USP232 routes of exposure lists three: Inhalation, parenteral and oral. USP 1151 lists considerations for route of administration into detailed categories that specifies topical drug products. My question is what PDE limits do you use for “topical” solutions/ointments/gels? Anyone have experience with this?