White denotes purity

psychologically some colors denotes a specific meaning...white for purity, yellow for mental freshness etc..so its a fact

I also think 'white' is oftentimes used symbolically to signify purity. In many cultures, the word 'white' is used as an adjective for good things such as a white knight is a company that comes in to save a company in trouble. In many movies, guys in white are the good guys while the guys in black are the bad ones. So Luke Skywalker, Princess Leia and Hans Solo wears white but Darth Vader is garbed in black and so are the Evil Emperor and the devilish Siths in the Star Wars series. Also white magic as in Lord of the Rings is magic to do good compared to the black magic of the evil forces that wanted the ring.

There is actually nothing factual about white being pure even though moslems are buried in white shrouds. I believe white is a colour of purity in many folklores and has been used today for virgin brides who dresses in white on their wedding days.

It has throughout history to many groups of people, so I think that makes it a fact. I'm sure you could say some other color symbolized purity, since dirt can be any color, even white, but white is the clearest color. Unless you count transparent as a color.