Alcohol has physiological effects on the human central nervous system at blood alcohol concentrations (BACs) as low as 9 mg/dl. It is unknown, however, if humans can perceive the effects of such low doses of alcohol. Furthermore, low BACs can be difficult to measure. The purpose of this experiment was to: (1) assess the ability of humans to perceive subjective effects of low BACs; (2) measure behavioral effects of low BACs on a psychomotor performance task; and (3) test the sensitivity and accuracy of the transdermal alcohol sensor (TAS) for measuring low BACs from skin. Five men and seven women were administered single-blind intravenous infusions of ethyl alcohol in 5% dextrose/water to achieve peak BACs of 0, 10, 20, and 40 mg/dl. Subjective intoxication scales and a computer administered continuous performance task (CPT) were used to assess alcohol effects. BACs were estimated from skin, blood, and breath. The only alcohol-induced sensation significantly increased during the alcohol infusions was anesthesia measured by the Alcohol Sensation Scale on the descending limb of the BAC curve. The subjective positive-reinforcing stimulant and mood effects of alcohol were not reported until subjects were administered the 40 mg/dl alcohol infusion. Other measures of subjective intoxication and sedation, and the CPT were unaffected by the alcohol infusions. The TAS provided a noninvasive method for estimating BACs that was comparable with estimates obtained from blood and breath, although delayed in time.

The metabolism and toxicity of the ubiquitous plasticizer, bis-(2-ethylhexyl) phthalate (DEHP), and its principal metabolite, mono-(2-ethylhexyl) phthalate (MEHP), have been extensively investigated. In an attempt to understand their disposition in man, we studied the in vitro serum protein-binding characteristics of these compounds, using ultracentrifugation and agarose gel electrophoresis. The association of DEHP and lipoproteins was shown to be highly dependent upon, and proportional to, the lipid concentration of the serum. It appears that more than half of the serum DEHP is bound to proteins with density greater than 1.21 g/mL when the concentration of cholesterol is below 300 mg/dL or the cholesterol and triglyceride total concentration is less than 600 mg/dL. As the cholesterol and triglyceride concentrations increase, the percent DEHP bound to VLDL, IDL, and LDL increases. MEHP is bound principally to nonlipoprotein constituents in the serum, and this binding distribution is unaffected by lipid concentration. The percent binding of DEHP and MEHP to individual proteins was also found to be unaffected by their concentrations in serum. These data indicate that the protein-binding characteristics of these compounds, in vitro, is somewhat more complex than previously reported.