Answer to Question #12513 Submitted to "Ask the Experts"

I have a superior magneto Corps of Engineer compass from 1944. It has a crack in the glass. I am aware now that the faces inside were painted with radium paint. I bought it and put it on a shelf in our game room at about waist level. My two-year-old son plays next to this shelf every evening for a few hours. One day he actually grabbed it off the shelf and was handling it. I got up and took it from him and placed it back on the shelf. I later began to read about possible radiation hazards of these compasses I haven't found much in exposure to children. I'm still not quite sure if I should be worried for my son's future safety. My main concern is the fact that he is so young. Even if worst-case scenario he licked the compass how worried should I be? I've read that the radium turns to dust and the inhalation is the main concern. I kept this cracked compass in a jacket pocket for about five hours before bringing it home. Should I assume that that pocket is contaminated? Would simply washing the jacket suffice? Should I get rid of the jacket? Or am I just being paranoid? I'm very worried that my son may someday get bone cancer or something from my negligence.

The short answer is that there is nothing to fear from the radium dial. I will add some supporting information below. 

Much of what we know about health effects from radium comes from the women who were radium dial painters in the 1920s. Their practice was to make a fine point on their paintbrushes with their lips in order to paint the radium paint on small letters or numbers on radium illuminated instruments (such as your compass). So, they ingested some radium each time they licked the brush. The daily quota for a dial painter was in the hundreds, depending on the item being painted. Even when ingesting paint from hundreds of dials daily, not all of them ended up with cancer. So, the bottom line, with regard to your son's possible exposure, is that neither he nor you would be able to ingest enough radium to cause harm.

I have never seen radium paint turn to dust. I have an antique compass in which the radium paint has begun to flake away from the dial. However, the large flakes could not escape the glass cover, even if the glass is cracked. Thus, there should be no radium on the outside of your compass. To ease your mind, you could wipe off the outside of the compass with a tissue (discard in regular trash). Also, it is very unlikely that any radium would have escaped to the pocket of your jacket. You do not need to dispose of the jacket. Again, if you are concerned, normal washing should suffice to remove any radium dust.

Typical gamma readings from such antique devices is about about 3 microsieverts per hour (µSv h^-1) in contact with the glass face of the instrument. The limit given by the US Nuclear Regulatory Commission for external gamma ray exposures to the public (anyone without radiation safety training) is 20 µSv h^-1. Because we live in a sea of radiation from the ground and outer space, your son and all members of your family are likely receiving a hundred times or more radiation from normal background every day than you will get from your radium compass. 

I recommend that you enjoy your compass as an important historical artifact and not be concerned for the radium.