The test is so sensitive that critics claim it produces a significant number of false positives. The Substance Abuse and Mental Health Services Administration issued an advisory in 2006 that the EtG test should not be used as the sole basis for taking any legal action against someone who has a positive result.
The manufacturer of the test, Redwoood Toxicology Laboratory, is facing at least one lawsuit claiming its test is "inherently faulty." The lawsuit claims that Redwood does not inform its customers -- law enforcement, probation offices, and employers -- that the test will return positive results for coming in contact with household products that contain alcohol.


