Over a period of several days I have been working on cars and washing parts (and my hands) in gas containing ethanol. Today I spent most of the day with my hands emersed in gas. Tonight at IOP I was giving an ETG test. I told my counselor about my concerns and she indicated that the only way I would test positive was if I was drinking and that via the test that they could differenciate between these two types of exposure. What levels of EtG could be reached via this type of exposure and, how could the testing tell the difference

So did you pass or fail the test ?

I do not know yet.

I'm assuming this was a urine test?

Your counselor is badly mistaken. Any exposure to ethanol, including dermal exposure, can lead to a positive EtG. While you were washing parts you were furthermore inhaling fumes that contained ethanol, another route proven to create EtG.

It is now well established that EtG is not proof of alcohol consumption and can result from incidental exposure to thousands of environmental sources.

It really isn't possible to determine the level of EtG that could be present, too many variables involved. Hand Gel (ethanol based), has been shown to register as high as 770 ng/ml. Well above the cutoff of most tests. Of course hand gel is usually above 60% ethanol while the gasoline would be around 10-15%.

Following is a website managed by Dr. Greg Skipper. He introduced EtG testing in the US and does a decent job of posting information about the use and limitations of the test. As you will note, it isn't possible to determine the source of EtG:

Ethyl Glucuronide