Table 2.

Main characteristics of the study biomarkers.

Biomarker	Characteristics	References
EtG	Obtained from urine. Sensible to urine infections and reduced kidney function. Suitable for abstinence monitoring. Time-frame of detection up to a few days. Cut-off 0.5 mg/L	[15,16,17,19,20,27,28,29,30]
EtS	Obtained from urine. Sensible to urine infections and reduced kidney function. Suitable for abstinence monitoring. Time-frame of detection up to a few days. Cut-off 0.05 mg/L.	[17,19,20,31,32,33]
PeTH	Obtained from dried blood spots. Suitable for abstinence and heavy drinking monitoring. Timeframe of detection from days to weeks. Cut-off 20 ng/mL	[19,21,22,23,24]
HEtG	Obtained from hair. Sensible to contamination and extraction methods. Suitable for abstinence monitoring over long periods of time. Timeframe of detection from weeks to months. Cut-off 7 pg/mL.	[19]

EtG: ethylglucuronide; EtS: ethylsulfate; PeTH: phosphatydilethanol, HEtG: hair ethylglucuronide.