The spot checks occurred in Etobicoke, Canada, from Oct. 1, 1977, to Sept. 17, 1979. Results showed discrepancies. A significantly higher proportion of younger drivers were requested to submit to a roadside screening device but a greater proportion of older drivers, particularly females, registered a 'fail' (over 80 mg/100 ml). The results of the independent roadside survey of the same region found no differences in the proportion of younger and older drivers with readings over 80 mg. Although the nature of the study precludes any firm conclusions, hypotheses are offered as interpretations of these findings. Tables and 17 references are included. (Author abstract modified)