Listerene strips contain:
Pullulan , Menthol , Potassium Acesulfame , Copper Gluconate , Polysorbate 80 , Chondrus Crispus (Carrageenan) , Glyceryl Oleate , Thymol , Eucalyptol , Methyl Salicylate , Ceratonia Siliqua (Locust Bean) Gum , Propylene Glycol , Xanthan Gum , Aroma (Flavor) , Blue 1 , Green 3.
No alcohols of any sort, so the alcohol could only have come from a different source, possibly a can or a bottle.
Menthol in anything is something that you are warned to avoid if you have an IID installed on your auto (as is pretty much any mouthwash).
Lots of things can cause readings down in the 1% range. Food Lion Diet Ginger Ale does it for me (or used to, anyway).
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