Linked from
The 13 pages that link to Photodegradation, each with the reason it gives.
Food coloringRelated: Light can break down colorant molecules during storage or display.
UltravioletRelated: Ultraviolet exposure degrades polymers, pigments, and other materials.
Thermal degradationCompared with: It is initiated by absorbed light rather than heat alone.
Chrome yellowRelated: Light can alter chrome yellow and contribute to darkening or fading.