Ethyl alcohol, hereafter simply referred to as alcohol, is second only to caffeine as the most widely used drug in our society. An estimated 16 million Americans over the age of 12 use alcohol heavily, incidences 8 times higher than that of cocaine use. Since alcohol is a legal substance, many employers choose not to test for it as part of their urine drug testing program. Typically, a urine alcohol test is performed using a biochemical method in which alcohol, if present in the specimen, oxidizes to acetaldehyde in the presence of alcohol dehydrogenase. Simultaneously, if alcohol is oxidized, Nicotinamide adenine dinucleotide (Now in the reagent is reduced to NADH. The concentration of alcohol is derived from the spectro-photometric analysis of NADH. The most common confirmatory method is gas chromatography with flame ionization detection. Typically, the screening and confirmation cutoff concentrations for alcohol are 0.04 or 0.02 g/dL.
Urine, Blood and Breath Analysis
A major limitation to alcohol testing in urine is that the concentration determined in a single urine specimen does not correlate well with the blood alcohol concentration. A urine alcohol concentration is related to the average blood alcohol concentration during the time the urine was produced in the body, which can extend several hours before the specimen collection. If there is a need to correlate the urine alcohol level to the blood alcohol concentration (e.g., for purposes of establishing impairment}, a 2-step urine collection (2 voids produced 20 – 30 min apart) should be used to obtain urine produced during a time more closely approximating the time of collection and thus more closely related to the current blood alcohol concentration. Only the second void is sent to the laboratory for analysis. Many studies have attempted to correlate urine alcohol concentrations. Most of these studies have shown that the urine alcohol concentration is about 1.3 tones that of blood, but huge variations were observed. MROs should be aware that diabetic glucosuria is also known to be associated with positive findings of alcohol because of fermentation. MROs should require that laboratories also concurrently perform and report findings of tests for glucose in urines that are positive for alcohol.
Another evaluative test that is being promoted by some as an indicator of alcohol abuse is ethylglucuronide (EtG), a metabolite of ethyl alcohol, but this and other biomarkers are controversial since their presence has been detected in urine even from dermal absorption of alcohol. SHAMSHA has issued a warning about their use in workplace testing programs.
Some employers use blood for alcohol testing. The major advantage to using blood is that an individual may be legally considered under the influence or intoxicated if his or her blood alcohol concentration exceeds a defined concentration. The obvious disadvantage to performing a blood alcohol test is that specimen collection involves an invasive procedure and requires personnel with training in phlebotomy. Another disadvantage is that the blood specimen must be tested separately from the urine specimens, which increases costs. Since most laboratories do not want to assay blood on the same instrument used for urine drug testing, a separate instrument is typically used. The biochemical method previously described can be used for blood as well, although many laboratories determine blood alcohol directly by gas chromatographic techniques.
In tests where alcohol is tested as part of a drug screen panel, either in urine or blood, the MRO may be involved in reviewing the results if the employer decides to use an MRO. It is important that the employer set up written policies governing the action that will be taken in the event of a positive finding for alcohol. These policies may vary significantly among employers, including differing definitions of what constitutes a positive test or policy violation. If an employer has a ‘zero tolerance’ policy, for example, where urine alcohol testing uses a 0.020 g/dL cutoff for a positive test, the employer should be made aware of the fact that some OTC medications and food preparations contain enough alcohol to produce a positive test result, depending on the timing of the wine specimen collection.
Because many alcohols, including ethanol, methanol, and isopropanol, are common industrial solvents, occupational exposure may also be a concern. However, extreme exposure conditions are necessary for sufficient absorption of alcohol through skin or inhalation to result in a maximum blood alcohol concentration exceeding 0.040 g/dL. Alcohol absorption through the skin is usually considered negligible. However, significant absorption has been noted in cases involving infants and the elderly. In these cases inhalation, as well as percutaneous exposure of relatively large areas of sling for many hours to days resulted in blood alcohol concentrations of 0.010 to 0.062 g/dL. It is difficult to imagine an occupational exposure that would result in sufficient absorption through the intact skin to result in a positive test.
The determination of alcohol in breath is a common practice in workplace and law enforcement settings. In addition to being a noninvasive technique, the concentration of alcohol in breath correlates well with whole blood. Ethanol is volatile and thus, the amount of alcohol in proportion to the concentration in the blood transfers from the blood into the alveolar sacs in the lungs. The in vitro relationship is frequently expressed in accordance with Henry’s Law which states that the alcohol concentration of the gas phase at constant temperature is solely a function of the alcohol concentration of the liquid phase. Breath alcohol analyzers are calibrated in units of grams of alcohol per 210 L of breath and the evidential breath testing devices provide quantitative readings in these terms E:. breath alcohol = 0.08 g/210 L). Breath alcohol measurement in workplace programs is most commonly accomplished using electrochemical oxidation/fuel cell, gas chromatography, or infrared spectrometry.