This was a nationally representative study to estimate the prevalence of alcohol and other drug use among drivers. Drugs studied included 98 over-the-counter, prescription, and illegal substances. Drivers were randomly selected at 60 sites (300 locations) across the continental United States. Data were collected during one 2-hour Friday daytime session (either 9:30 to 11:30 a.m. or 1:30 to 3:30 p.m.) and four 2-hour nighttime periods (10 p.m. to midnight and 1 to 3 a.m. on both Friday and Saturday nights). Participation was voluntary and anonymous. Data included observational, self-report, and breath alcohol tests from 9,455 drivers, oral fluid samples from 7,881 drivers, and blood samples from 4,686 drivers. This report focuses on drug test results and provides results of combined alcohol and drug use. Results are compared to the 2007 National Roadside Study, for the first time presenting trend data on drug-positive driving. Using data from both oral fluid and blood samples, overall, 22.3 percent of daytime drivers and 22.5 percent of nighttime drivers were drug-positive. Delta-9-tetrahyrdacannabinol (THC), the active component of marijuana, was the most frequent drug, with 8.7 percent of daytime drivers and 12.7 percent of nighttime drivers testing positive. When comparing the 2013-2014 results to the same drugs tested for in 2007, an increase in nighttime drug prevalence was found between the 2007 and 2013-2014 NRS, from 16.3 percent to 20.1 percent, a statistically significant finding. This study estimated drug prevalence. A positive result for any drug does not necessarily mean the driver was impaired at the time of testing, only that the drug was present in the body. Data from this study cannot be used to draw conclusions about drug-impaired driving. (Author/publisher)
Samenvatting