Ask A Scientist Chemistry Archive

name         Carol S
status       student
age          50s

Question -   What chemical (other influence) can change a yellowish
(eggshell) colored paper to white within hours of exposure under
fluorescent lights?  Is it harmful to humans?
It all depends upon what the "yellowish substance" is. If it is food dye,
certainly U.V. radiation can bleach it to a colorless substance. If the
"yellowing substance" is iron oxide, for example, it will not bleach very
readily. The toxicity of the substance will depend upon what the substance
is.

Vince Calder
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Carol,

That would be UV (ultraviolet) light.  Yes it can be harmful to humans,
much as the UV from the sun can be.  What matters is the intensity and the
time of exposure.

Don Yee
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