No one can get any more info from the EPA than they feel like giving out. EPA like FDA is a giant bureaucracy with someone popping out from behind a closed door at any moment with their own question from hell - like playing Whack A Mole in slow motion, except you have to deal with each one's question or do more experiments to deal with it.
They can take their investigation in any direction they feel and no matter how well prepared your application is, there is no guarantee they won't ask questions that make more experimental data necessary. No one like MZEI does their application on their own - you have to hire specialized EPA consultants to help you with it, so complaining that mgmt can't get the job done isn't likely the reality.
I have a sterilizer device stock, not in the room cleaning arena, that started meetings with the FDA since January 2010 and was told in August 2014 that approval is a done deal, but labeling will take 2 more months because it has to be done in a way that FDA employees will accept even though they have already approved that the device works, but so many FDA'ers are involved that it takes 2 months to go over it and do the explanations of what to say etc. ...............In May 2012 out of nowhere a bureaucrat made the decision this device was so novel that it had to be applied for under du novo guidelines - never mentioned du novo previously - that is bureaucracy for you.
