The one vocal health issue that seems to haunt every singer's dreams is vocal nodules. "Vocal fold nodules or nodes can be compared to calluses, usually appearing as a result of friction because of an incomplete closure of the glottis: singing with a hoarse [or breathy] voice can produce nodules.
Forcing your voice to do things it can't, and providing inadequate breath support (causing 'wild' air to escape through the glottis) are other potential causes. You can get nodules after just one night of overusing your voice! Nodules [generally] develop in pairs, one on each fold.
Women are more at risk than men." (Pinksterboer, H. Tipbook Vocals: The Singing Voice. 2002) Over the years it has been thought that any form of contemporary singing would result in nodules and other forms of voice disorders, and while genre's such as 'Heavy Metal' punish the voice with coarse phonation, generally most singing that is supported by a well informed and trained voice should avoid vocal injury's such as nodules.
A link to the original article (and many more that delve deeper into the world of vocal care) can be found here, courtesy of Dr.Dan: www.djarts.com.au/articles/nodules/