There is a difference of exposure to radiation to a black shirt and a white shirt but I think the difference is so insignificant that it’s not even considered different. The effects of radiation wearing a dark colored shirt on a sunny day to humans is probably not significantly different enough to warrant not wearing your favorite band tee out of fear you will get radiation poisoning.
But there is definitely a difference in heat. If you insist on wearing a black shirt and you want to avoid having a heat stroke then you should probably consider bringing water, maybe an extra shirt and sun screen if you have to be outside for more than 10-15 minutes.
Under the sun, the black shirt absorbs all wavelengths (more light). A white shirt reflects the visible light that hits it.
heat follows the same laws of conservation of light energy. This means light energy and heat cannot be created or destroyed. The light and heat has to go somewhere.
The light doesn’t cause the heat but they follow the same rules so instead of visually seeing the lack of light, you feel the heat energy that is being absorbed by your shirt.
you are exposed to the same amount of radiation wearing a black shirt as you are the white shirt. The difference is the “color” (because some people don’t consider black and white a color) and how light reacts to it.
I hope I was able to help!! This was a great question :)!!