It's not just about wavelength, an LED with a "safe" wavelength range (e.g. a red LED) can and will fog paper if there is enough intensity. I've attached the SED of a flashlight that I measured (that I use- carefully - in the darkroom), output is zero shorter than about 575nm but it will definitely fog MGIV RC paper if you hold it close for a few seconds.
The answer is always to test, there are detailed but easy to perform methods described on Kodak's site