It is hard to imagine a more stupid or more dangerous way of making decisions than by putting those decisions in the hands of people who pay no price for being wrong.  -Thomas Sowell

EtG stands for ethyl glucuronide and is the index case and prototype for a vast array of unproven forensic tests introduced to the market as Laboratory Developed Tests ( LDTs).

The LDT pathway was developed for laboratory tests that would not otherwise come to market due to the prohibitive cost of FDA approval (for example a test for a rare disease). Bringing an LDT to market does not require testing in humans (in vivo). Nor does it require that it be shown the test is testing for what it is purportedly testing for (validity). It is essentially an ”  honor system. It was not designed for “forensic” testing but for simple clinical testing with low risk.

None of this testing is approved by the FDA. It is essentially an unregulated industry.

NMS became a leading proponent of EtG testing and, starting in 2003, began publishing claims promoting the absolute validity and reliability of the EtG in detecting alcohol. Akin to the vitamin and supplement industry those promoting and selling the tests could say anything they want—and they did.

NMS initially established a reporting limit or cutoff of 250ng/ml at or over which EtG test results would be reported as “positive” for drinking alcohol. This was later upped to 500ng/ml, then 1000 ng/ml.

NMS reported it as the “Gold Standard” claiming any value above 250 ng/ml indicated “ethanol consumption.”

It was subsequently found to be so sensitive that it could measure incidental exposure to alcohol in foods, over the counter cold medications, mouthwash, hand sanitizer gel, nonalcoholic beer, and nonalcoholic wine and we now know there is no cutoff limit that can differentiate drinking from outside and innocent exposure.  Labs such as Quest and USDTL, however, want you to believe otherwise.

Source: Quacks Selling Snake Oil-EtG and the Big Con.