In many countries risky drinking is common. Worldwide more than 5.1% of the overall global health burden is associated with alcohol misuse and this percentage is rising. Most of the time, harmful drinking is temporary, but over the course of a lifetime, 15-20% of the entire U.S. population will have a more chronic problem, some even diagnosed with an alcohol use disorder (AUD). Many are not aware or deny their drinking is a problem, and most individuals need help to reduce their alcohol consumption to safe levels. Acute alcohol is commonly by breathalyzer or blood ethanol tests; however, these tests could only detect alcohol within hours after consumption. For chronic alcohol use and abuse, long-term alcohol biomarkers are needed. There are several direct alcohol biomarkers in use but it is generally agreed that phosphatidylethanol (PEth) is the most reliable long-term alcohol biomarker currently known. After alcohol ingestion, PEth remains in red blood cells (RBC) up to 30 days or longer. PEth is currently measured by mass spectrometry, but the turnaround time is slow (>1 week) and the cost is high. Echelon Biosciences recently developed PEth ELISA for research use only which significantly lowered the cost and turnaround time. The improvement was significant, but due to the nature of PEth incorporated in RBC membranes, an extraction step is needed before ELISA detection. The goal of this Phase I project is to demonstrate feasibility of a prototype rapid point-of-care PEth competitive lateral flow immunoassay (POC-LFI). Echelon has partnered with an LFI expert, Dr. Richard Watt at Brigham Young University, to improve the consistency, sensitivity, and preanalytical methods to create an in vitro PEth LFI approaching 10 ng/mL for abstinence monitoring, and ex vivo methods for whole-blood clinical detection of PEth at concentrations ≥ 200 ng/mL to detect excessive alcohol consumption. The success of this project will fulfill an unmet need in the alcohol testing market. There are multiple settings and application for POC testing including AUD assessment, workplace security, assessing alcohol exposure in neonates, forensic/legal cases, and importantly help clinicians and caregivers identify problem drinking and help these individuals receive the treatments they need.