Methanol has a different metabolic pathway and should not generate EtG. However, methanol is often used in denaturing ethanol (denatured alcohol, methylated spirits) and some paints and strippers use this combination as opposed to straight methanol. Inhalation of denatured alcohol, methylated spirits (anything that contains ethanol in combination) will create EtG.

I'm currently checking to see if there has been any research or reports on methanol vapors in relation to EtG, just to be sure I didn't miss something.

Followup: EtG is a phase II metabolite (later stage) of ethanol, and the later stage enzymatic breakdown of methanol is, as indicated above, via a different system although both ethanol and methanol are initially broken down by alcohol dehydrogenase (ADH) from that point their paths diverge.

In addition, I found no research on the subject (chemically pure methanol/EtG) although, as noted above, there are cases involving methylated alcohol.

Research to date emphasizes 100% specificity of the EtG test for systemic ethanol. But most of the claims for this bio-marker have proven errant so I wanted to double check.

I used to work in a bio-diesel plant using methanol/Methoxide in this process, and have failed an EtG test from what appears to have been vapors/exposure
At work, My understanding as explained by our in house scientist is that methanol and ethanol molecules are almost identical, and that ethanol breaks down into suger and water, and methanol is transformed into formaldahide. What are these different pathways ? And what about exposure to gasoline containing ethanol ?

The information you received is correct... as far as it goes. EtG is left behind in the wake of the process of transformation you cite. In second stage metabolism Aldehyde dehydrogenase (ALDH) transforms Acetaldehyde which was created by Phase I ethanol metabolism. Whereas, Phase I metabolism of methanol reduced it to formaldehyde and in Phase II formaldehyde dehydrogenase is the active enzyme. Phase I metabolism of both is an oxidative process fueled by the enzyme alcohol dehydrogenase (ADH). There is a molecular similarity, they're of the same family, alcohol.

As to your question about gasoline containing ethanol. Inhalation can create EtG. Anything containing ethanol, ingested or inhaled can.

I doubt that the source of your of your EtG was methanol, but there is no research that I've found to directly challenge that theory and I have not personally dealt with this issue previously. But there are so many sources of incidental exposure to ethanol, that would be the general direction of my gaze.

What was the EtG reading? That's a good place to start.

My main point isn't to directly challenge your idea. Rather first to turn to to established science as opposed to venturing into heretofore unexplored regions.

Thank you for your help. It has been very informative and will give me cause to investigate further. If you find anything more on this subject it would be of much help.