EtS levels are approximately 1/4th of EtG levels, but there's significant variation on this pattern. EtG can be degraded by bacteria sometimes but EtS hasn't been shown to be degraded. Additionally, there are different enzymes for these two metabolites. The bottom line is that a positive EtS and/or EtG should be considered a positive screening tools for recent drinking. If drinking is denied then confirmation is needed. Confirmation can best be attained by another test or technology (such as blood phospotidyl ethanol or using a SCRAM device) or further evaluation (with or without polograph), antabuse, or just waiting and watching, as you know, addiction tends to show itself.
EtG hair testing may soon become commercially available in the United States. There are numerous studies that show that hair testing may be accurate and helpful, however, it's important to realize that hair EtG has a much different meaning than that in urine. Hair is a repository matrix. It is not known how much drinking is neccessary for hair EtG to become positive, however, the amount is likely significant. Therefore, hair EtG testing is not a test that is sensitive for detection of abstinence (despite what some labs may caim). Hair EtG will not likely detect small amounts of drinking. When positive it does appear to be well correlated with amount of drinking over time.
Important Facts About EtG (ethylglucuronide) and EtS (ethylsulfate) Testing