Both sound high to me. 50K would be 500 programs with 100 participants. But, who knows. No, I don't mean that TheWho knows, but who really knows? Are you interested in only private-pay facilities or state-run as well?
As for the deaths. That sounds high too. I keep a file in Excel and there's about 140 since 1980. There may be others. I know some don't make the news. I found one last week from like, 1990.
Can't even guess at the number of injuries, physical/sexual attacks, long-term medical conditions, emotional distress (PTSD, etc), post-program suicide, etc,etc.
You might get an idea by compiling a list from ST and NATSAP. If they're licensed there will be a maximum enrollment figure, but, that would be a tedius task.
If we had several people, each person could take a state (or two) and research the programs in that state.