If the cutoff level for showing positive of alcohol is 20pg/mg, is a level of 26pg/mg have a quantitative measurement of alcohol use or show excessive use of alcohol

It shows use that exceeds the cutoff. What that means on a per person basis is variable. On some that could be excessive drinking and others could be just casual. Regardless it shows a failure and not just a slim failure but a solid one.

Agree and that is 30% above the cutoff.

Who is ordering the test/what is the purpose? Employment? Post accident? Drug court? Other? Are you of legal drinking age?

Since you are only 6 pico grams over the cutoff I would say that is not that much. I've seen some pretty outrageous levels of other drugs. Also keep in mind who is requesting the test and why are they requesting it. To them anything over the cutoff level my be outrageous intake of alcohol.