Cantilena, I'm sorry, but I really disagree with you on that. screaming is safe if you know how to do it. A scream in heavy metal is not yelling, it's distortion, it is a hyper-compressed vocal effect. "Screaming" is a deceptive name for the vocal effect because it sounds like screaming, but it's not. Metal vocalists have been doing it for years. I've done it for quite a while myself (a year or more) and I have not experienced vocal trauma, injury, pain, discomfort etc. in fact, I don't feel anything unhealthy at all. I practice this technique very frequently. My SLS teacher, who I didn't learn it from, even says is sounds safe.
In 2007, a joint study from CVT and an ENT surgeon ran a research program with a bunch of speech level therapists and determined that growling and distortion are safe if done correctly. Check out the video on the CVI website:
http://completevocalinstitute.com/vocal-technique/research/
Sorry, you may be a student, but these ENT's and speech level therapists are in the field already practicing, they have more credibility.
But of course, if you want to provide a counterargument, go for it.
Tyme: there was a point in time that I tried it the wrong way, before I knew the correct way, and really did hurt myself. I still practiced it while in pain, but eventually realized it was being done wrong so I took the time to get training and go through recovery. Did I get it checked out? No, there is no need to panic about everything.
Learn the correct way, there are plenty of sources out there like CVT and TVS that can help you with distortion. Recovery won't happen fast, sorry. Wounds take time to heal. Go on vocal rest for a while by not talking for a few days. Nodules actually are a risk, I happened to be lucky it wasn't severe. If symptoms persist, you actually might have to get them checked out.