Answer to Question #2777 Submitted to "Ask the Experts"

Q

I understand that UVA (ultraviolet A) rays from a tanning bed do not penetrate the surface skin. Even a thin layer of clothing will block the rays. Can the more powerful tanning beds that mostly generate UVB (ultraviolet B) rays and some UVA rays affect breast milk for nursing mothers? If so, would clothing also block these rays from effecting the breast milk?

A

Regardless of wavelength (UVA, UVB, or UVC), ultraviolet light doesn't penetrate all the way through the skin into underlying organs. UVA wavelengths, in fact, are longer than UVB. About 20% of UVA radiation will penetrate to the live layer of skin though not any farther. UVB wavelengths are generally stopped by the dead layer of skin though about 10% get through to the live layer. Tanning beds are regulated so they should not emit UVB radiation. UVB radiation exposure has been linked to a higher incidence of melanoma. So, if you're using a tanning bed emitting UVB radiation, you have more to worry about than effects to breast milk. In any event, UV radiation exposure external to the body will not affect breast milk. Kelly Classic Certified Medical Health Physicist Reference Sliney D, Wolbarsht M. Safety with lasers and other optical sources. New York, NY: Plenum Press; 1980.