Alcohol and motorcycle riders: a comparison of motorcycle and car/truck DWIs.

Alcohol's effects on balance and motor coordination would be expected to have greater consequences for motorcycle riders than car/truck drivers. Driving while intoxicated/under the influence (DWI) reports for 1984 and 1985 from the San Antonio, TX, Police Department were reviewed to evaluate motorcycle DWIs, and to compare them with car/truck DWIs. During the 2-y period there were 100 DWI reports involving motorcycle riders, which were compared to 100 involving car/truck drivers. Motorcycle riders were all male and younger (mean 26 y) than car/truck drivers (p less than 0.05). Initiation of the DWI investigation of motorcycle riders was more frequently due to excessive speed, and less likely due to an accident, when compared to car/truck investigations. Breath alcohol testing demonstrated a significantly lower blood alcohol concentration in motorcycle riders, 0.14 +/- 0.05 g/dL, than in car/truck drivers, 0.16 +/- 0.05 g/dL (p = 0.016). The results of this study suggest that alcohol influences motorcycle riders to a greater extent than it does car/truck drivers. Further data is needed to determine whether lower blood alcohol concentration limits should be considered for the definition of "driving while impaired" in motorcycle riders.