"UV" covers a WIDE range of wavelengths. For understanding, 3 subranges are relevant to this situation:
UV-A is 400 – 315 nm. It includes plain ol' visible purple colors. It's "blacklight". It causes fluorescence of blacklight posters. Almost ALL "UV LEDs" are UV-A- most are 395 nm, some 365nm. It has relatively little biochemical or photochemical action, but is weakly implicated in skin cancer- surely not until the shorter wavelengths.
UV-B is 315 – 280 nm.
UV-C is 280 – 100 nm. THIS is a germicidal lamp (not done with LEDs). It's DANGEROUS to eyes... and skin... and would NEVER be sold in an application where people would be exposed to it. And it'll damage many types of plastics.