We are planning to buy a "glow in the dark" blanket as our seven month old daughter finds it fascinating. However are there any health concerns with using "glow in dark" stuff. I understand they use radium for the glow effect. Does it cause any long term health hazard.
[Note: I can't post images, please edit if you can]
I've never heard of glow in the dark bedsheets. They definitely do not contain radium, which is deadly poisonous. There was a mass poisoning of workers, the Radium Girls in 1917, if you want to read a horrible story.
Today's glow in the dark materials need to be charged with light and then glow for some time, from minutes to hours, in contrast for the radioactive ones, which glow for years.
Phosphorescent materials are typically oxides or sulfides, doped with rare earths. These materials are mostly harmless (but not made to be ingested), you can find material safety datasheets for many materials here.
Of course, that does not help you, because you don't know if the overseas manufacturer really used a safe material.
If you want to do something really cool, here are some totally safe ideas:
The green stuff lasts longest, the red ones glow for only a short time. If you'd like to do a correct image of the sky, you can buy a cheap star projector to get the positions on the ceiling and then paint the stars in place.