Does this mean that with every scientific advance giving greater precision in detection methods every existing product must be re-evaluated? (And perhaps be found in violation by newer, more stringent detection methods?)
Don't peppermint and/or spearmint contain menthol as a component of their oil?
The TTB seems to be hedging their bets. There's no reason to test for more than 10 ppm thujone if your limit is 1 ppm.
It's been demonstrated that thujone tends to come over later in the process and that the timing and concentration of it can be manipulated to an extent.
imho, a better solution is to seek out naturally occuring thujone-free (or even low thujone) A.a. chemotypes having a quality flavor profile. That way you start with t-free or at a value so low that whatever comes over falls below the limit of detection. Until the next great scientific advance, that is. Hopefully, by then they (TTB and FDA) will have drank enough absinthe to their senses.