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Affiliation
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Southern California Research Institute , 7065 Hayvenhurst Avenue, Suite 9, Van Nuys , CA 91406. |
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Abstract
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STRUCTURED ABSTRACT Background: Two of the three standardized field sobriety tests that US law enforcement uses at roadside checks have a postural equilibrium component to them. Those tests have been validated to detect impairment caused by blood alcohol concentrations (BACs) of.08 g/dL or above. Many medical and traffic safety associations support a lower limit, and one state, Utah, has passed a law to lower the limit to.05 g/dL. Many studies have examined the effects of alcohol on postural control (of which postural equilibrium is a component), with a consensus emerging that impairment is usually found at BACs greater than.06 g/dL. Most of these studies, however, had a relatively small number of subjects, usually between 10 and 30. The current study collected data from a much larger sample.
OBJECTIVE: The objective of this study was to provide additional evidence that posture control is negatively affected at BACs greater than.06 g/dL or breath alcohol concentrations (BrACs) of.06 g/210 L.
METHOD: This was a between-subjects study, with BrAC group as the independent variable (five levels:.00 g/210 L,.04 g/210 L,.06 g/210 L,.08 g/210 L, and.10 g/210 L); four measures of postural control as the dependent variables; and age, height, and weight as the covariates. Posture control was measured with a force-sensing platform connected to a computer. The feet's center of pressure (CoP) on the platform was recorded and the corresponding movement of the body in the anterior-posterior and lateral planes was derived. Participants (N = 96) were randomly assigned to one of the BrAC groups. Positive BrACs groups were compared to the zero BrAC group. Data were examined with hierarchical multiple regression.
RESULTS: Adjusted for age, height, and weight, the main effect of Lateral CoP with eyes open was not statistically significant. There was a statistically significant main effect of alcohol on Anterior-Posterior CoP Excursion with eyes open and with eyes closed, and Lateral CoP Excursion with eyes closed. For all three of those variables, only BrACs of.08 and.10 g/210 L produced differences against zero BrAC. Although the main effect of alcohol on Lateral CoP Excursion with eyes open was not statistically significant, the contrasts between zero and.08 and zero and.10 g/210 L BrAC were in the hypothesized direction.
CONCLUSION: The current study did not directly address the issue of whether the sobriety tests are sensitive to BrACs of.05 g/210 L or above; rather, it provides additional evidence that postural control, one of the components of those tests, is relatively unaffected by BrACs lower than.08 g/210 L. Additional research is needed on the diagnostic characteristics of the sobriety tests at BrACs lower than.08 g/210 L.
Language: en |