A recent study conducted by researchers from the University of Sydney discovered that marijuana breathalyzers are still inefficient in testing for THC. For the study, they reviewed 28 older existing trials analyzing THC concentrations in the saliva and blood of drivers, and measured their performance. All they found were inconsistent findings. Specifically, they focused on studies that assessed the attention and reaction time of drivers, which are skills critical for safe driving. Though they did find significant links between impairment among inexperienced marijuana consumers and THC levels, when the drivers were already experienced users, the associations were gone.