Hello Dr. Bill,

Thank you for all of your help regarding this subject. The information you provide regarding the EtG test is invaluable. First, I wanted to share the results of some of the tests I have taken in order for others to be able to have the information. I am male, mid-30s, a little overweight, but in decent shape, used to drink heavily, but haven't for about a year now, EtG cutoff is 500. Once I tested 69 hours after last drink, where I had 6 standard drinks over the course of 3 hours. This was the last day of multiple days in a row of drinking, sometimes heavily. Another time, I tested 67 hours after last drink, where I had 3 standard drinks over the course of 2 hours. I passed both times.

I have read a lot of your posts and the queries of others regarding EtG elimination time. I am confused about something. In the past, you seemed to be more focused on the time since last drink, not BAC=0, as that is what the studies you cite measure, but in your more recent posts, you always figure time of BAC=0 and subtract that from time since last drink to get the true EtG elimination time. I understand this completely. It makes sense to do it this way as the body produces EtG until BAC=0. But what I don't understand is comparing that number to the published studies as the measuring times are not the same, so the results wouldn't be either. In other words, the studies don't measure elimination time from BAC=0, so why do we?

All the studies that you cite, unless I am mistaken, measure from time since last drink, not BAC=0. So, if we are trying to base our estimates off the published studies, why are we taking the extra step of putting in BAC=0 when the studies don't? For example, one of the studies tested highly intoxicated individuals (BAC .1 to as high as .3, unless I am readying that wrong). The study measured based on time since last drink, not BAC=0, and no subject tested positive for EtG somewhere around 85 hours or so (I apologize that I don't have the study in front of me, but I'm sure you know the one to which I am referring). If we calculated BAC=0, especially for the subject that had BAC=.3, wouldn't that mean true elimination time would be somewhere around 16 hours less (say, 69 hours if it was 85 since time from last drink)(.3/.018, which I believe is close to the estimate you use for ethanol elimination).

I hope what I am asking makes sense. If the studies are measuring from time since last drink, not BAC=0, why are we measuring from BAC=0 instead of time since last drink? If a study states that EtG clears within, for example, 50-62 hours since last drink, when 6 standard drinks have been consumed, why do we change our methodology and say that we will actually need 3-4 hours more than the study says we need to account for BAC=0? Because the study measure from time since last drink, not BAC=0, wouldn't we need to subtract the hours off the study result also to keep everything correlated correctly? For example, let's say that an individual consumed 6 standard drinks and cleared EtG in 55 hours since time of last drink. If BAC=0 3 hours after he quit drinking, doesn't that mean that the individual cleared EtG 52 hours since BAC=0? So, if I query that I had 6 standard drinks and will test 50 hours later, and you cite to a study that says EtG clearance time from time of last drink is 45-55 hours, if you then factor in that it will take 3 hours to get to BAC=0 and the actual time to test is 47 hours, don't we need to subtract that number from the published results also so it becomes 42-52 hours?

I guess what I am asking is if we are going to change the measurement for the starting point (time since last drink v. BAC=0), don't we also need to account for this change on the back end (by subtracting the number for time it takes to reach BAC=0 from the published clearance times, which are based on time since last drink)? After all, all the subjects tested had their BAC reach 0 during the time span from last drink to EtG clearance, right?

Just wondering as this has been confusing me lately. Thanks!

Sorry I missed this yesterday. Just now ran across.

I use BAC=0 because it provides a standardized starting point. Also because until that point is reached EtG is still being created.

If you go back and review most of the studies, particularly those involving detox patients, they are not measuring from last drink. Rather, from BAC at time of admission. No effort was made to determine number of drinks consumed nor time of last drink. Yet other studies measured from time of first drink, others from last drink and some have used blood or urine to establish BAC=0 and others have used the Widmark formula to estimate BAC.

Further complicating interpretation is that some have used urine EtOH as a marker but the collection times vary from every 2 hours to once daily. The cutoffs have also varied from test to test. Some use baseline 0 (Level of Detection, LOD), others 100, 250 and 500 ng/mL.

All of the foregoing impact time of EtG elimination as provided in each respective study and have been previously noted by Wojcik & Hawthorne, 2007. (1)

The study I believe you are referring to (2) was based on "breath ethanol concentration on admission," not last drink (see results). The test did measure to BAC=0 by breathalyzer and used 500 cutoff for EtG. EtG was detectable for 10-90 hours but there was no relationship to BAC at admission. In other words the person with .10 BAC may have been the one clearing EtG at 10-20 or 90 hours and the .31 may have cleared at earlier time.

So none of the detox studies come even close to providing a timeline for EtG from last drink. They cannot predict amount consumed, over what period. They provide little more information than that EtG can be detected in chronic alcoholics sometimes over a long period. Sometimes not. Tells us nothing about elimination.

The only study that comes close to projecting EtG clearance near the point of intoxication is Halter (3) measure from start of drinking, this was a controlled dose study with BAC measured in range from .05-.08. And Moore (4) with BAC of .08. Moore found "both EtG and EtS were detected in urine up to 41 hs after the start of drinking; 32 hs after the BAC had returned to zero."

Wojcik & Hawthorne (1) also predicted BAC=0 via estimation by the Widmark formula.

As a final example let me provide Helander (5) wherein he claims EtG is detectable 40-130 hours. However, he also tracked EtG from BAC=0 and that calculation reduced the time to 30-70 hours (median 56). Same subjects... different method of calculation.

You are correct that the time between last drink and BAC=0 should be deducted from clearance time.

I believe the studies I cited are available full text on line.


Ref.

1)Wojcik & Hawthorne, 2007
2) Beck, etal 2007
3) Halter, 2008
4) Moore, C. (O-2)
5) Helander, et al, 2008