https://www.gpo.gov/fdsys/pkg/CFR-2011-title42-vol5/pdf/CFR-...
These are horribly oppressive, bureaucratic, unnecessary requirements like "maintain basic scientific controls":
https://www.law.cornell.edu/cfr/text/42/493.1256
This also is a section, it's worth nothing, that consists mainly of references to lots of other, more specific, requirements. There's really no way of knowing what the violations are, other than to take the letter at its word that the violations are serious.
This isn't taxi medallions -- mess this basic stuff up, and you're putting people's lives directly at risk.