A few years ago I was teaching in Baltimore and noticed that one of my students had burned her arm. When I asked her about it she said that, because she had recently gone on medication that made her extremely susceptible to UV rays, exposure to her full spectrum light had caused the burn. I want to emphasize that this is rare. But it got me to thinking.
I had not ever connected the "full spectrum" claim on any particular brand of lamp with UV rays. I used to position my light in such a way that the light shone onto the side of my face and into the side of my eye. My glasses have a UV protective film, but that didn't do me any good where the light was not going through the lens of my glasses. My initial thought was about cataracts which run in my family. I lowered my light so that it only shines on my handwork. The added benefit to the lower light is that it reduced my eyestrain.
It later occurred to me that, if I had a medical condition that required very limited exposure to UV rays, I would probably talk to my doctor about the safety of using a full spectrum light. I'm not an expert on UV exposure, I am just trying to use some common sense.
I did do some limited research about Dr. John Ott who gave us full spectrum lights. He's a very interesting guy! Click the link to read more about him and the technology he started. It seems that the range of light varies from one full spectrum light to another. I'm not sure how you would tell which light has the most UVs.
I want to be very clear: I am not advocating that you give up your full spectrum light. Just be aware of that what it means when the box says full spectrum.