Originally Posted by jamier04
Isn't 130 hours after consumption the longest elimination period on file. And I thought that even after heavy drinking clearance times would less than the "80 hour window". I'm just a little confused. Could you please clarify? Thanks DrBill!
It sounds as though you have been doing a lot of reading. I'm happy to clarify my comments and hopefully the issue. 130 hrs seems to be the outer/upper limit for detection in the research literature. This was a test conducted in a detox setting with BAC levels on admission of .10-.34. In this same study, the average (mean) elimination period was 78 hours (range 40-130 hr). Therefore, the figures you mention above. There were only 32 subjects involved in this 2008 Swedish study
. The cutoff used was 500 ng whereas many testing agencies still use 100 ng.
Interpreting this (and all EtG) studies requires a more discriminating review. For instance, the time spans noted above (and most often quoted) were calculated from time of admission
. When calculated from "0" BAC upper window of detection fell to 110 hours and an average of 66 hrs (range 30-110). This "0" BAC was not determined by blood draw but by using Widmark's formula for estimation (this assumes standard elimination of ethanol based on population average not applicable to most heavy or problem drinkers).
Further, when applying urine dilution measure (normalizing creatinine) the upper limit fell to 70 hrs, an average of 56 (range 30-70). It is recommended this standard (U100EtG) See New Advisory
) be applied but in fact it seldom is in commercial testing.
Virtually negating the predictive value of this particular study (in addition to the estimation noted above) is that urine was collected only once during each 24 hour period almost guaranteeing that the reported figures are over-estimates.
Nonetheless, in my opinion, the only safe method for projecting the elimination curve is to use the upper-limit figure. All of the literature has found about a 4-fold variance between subjects studied.
At best EtG tests provide very erratic results that cannot be correlated to the amount of alcohol consumed except by referring to these tested upper-limits.
My overall point is that any attempt to calculate EtG elimination across a given time period for any individual really isn't possible based on current knowledge.
All of the foregoing is based on laboratory conditions, conducted by trained scientists using the most sophisticated instruments. They know how to interpret the results. Not considered are the many known problems with EtG: sample instability, environmental exposure to ethanol products, use of less reliable test products, inadequate training of personnel within the commercial testing industry and the fact that individuals synthesize EtG through a liver enzyme that is controlled by a genetic polymorphism.