Hello, this is Michael Peat and I'm going to talk to you today about alcohol testing and toxicology. I'm going to cover a subject in a very few minutes for which there are tomes of literature. And by tomes, I mean tomes. This is a subject that has been studied for decades now. If you remember and have read about the Grand Rapids study that associated alcohol use with increased accidents, that was in the 1950s. So that's as far back as this goes. The topics that I'm going to cover might be on the exam and therefore, if you are taking the exam, you probably should pay some special attention to this. Obviously as an MRO, you have no direct involvement in alcohol testing, but if you are an employee or an owner of an occupational health clinic or an occupational health practice, you will maybe ask questions about it or even ask to do the breath alcohol exams that Dr. Smith referred to. I think the important point here is that ethanol is the only drug which has a direct link between blood concentration and impairment. And that comment leads into my first slide on impairment. This slide is on the interpretation of alcohol results. Throughout this presentation, I've used the term alcohol, but obviously from a chemistry point of view, it should be ethanol. There are many alcohols and it's only the interpretation of ethanol results that we talk about, but the shorthand word is alcohol. It is the only drug for which there's a direct link between breath, blood alcohol and impairment. There's been considerable money spent on trying to determine that link, for example, for marijuana and impairment, and to date there's been no successful linkage calculated. Impairments are observed at blood alcohol concentrations as low as 0.02% weight per volume. Those impairments can be observed in divided attention tasks and in driving simulator tasks. For young drivers, those impairments are observed at concentrations lower than 0.02% weight per volume. In the world, there are certain countries that have zero tolerance for alcohol. Sweden is the best example, but there are other countries too. And in those countries, any alcohol on your breath is considered the per se and that you are impaired. In the US, there is a drive across the nation to lower the 0.08% per se to 0.05% per se. That drive recently has gained momentum, but if you remember back to the time when it was 0.1% per se and that was lowered to 0.08% per se, that required the federal government to threaten to remove federal funds for highways from the states that didn't lower their concentration. So it could be some time before the country gets to a standard 0.05%. For many states or in many states, for drivers under 21, the concentration is lower than 0.02%. In fact, it's zero tolerance for those individuals in some states. After peaking, the blood concentrations decrease at an average rate of 0.018% per hour, and that range varies from 0.005% to 0.03% per hour. Some literature quotes this as 0.02, some quotes it at 0.017. So there's variations in the literature, but I generally use an average rate of 0.018% per hour. And it's zero order kinetics. That's why the concentration decreases at a consistent rate. Next slide talks about urine alcohol. And I know this site won't be on the exam. It is an important slide. I've listed some properties of urine alcohol on this slide. I want to focus on the first bullet, which is urine concentration. It's approximately 1.3 times blood. In a few slides, I'll show you what the range is for that, and it's considerable. Usually to measure an accurate urine alcohol in terms of highway safety, usually the blood alcohol concentration peaks before the urine concentration has to. Conversion is only applicable after concentrations in blood and urine have peaked, and the bladder must be previously emptied within half an hour of the measurement of a urine collection. Those are very detailed prescribed factors. And as far as I know today, there are no states using urine for per se rules in alcohol testing. The bottom bullet is more important for you as MROs or occupational health physicians. High concentrations of glucose, for example, in uncontrolled diabetics can lead to production of significant alcohol after collection, but processes yeast fermentation in non-refrigerated specimens. Those alcohol concentrations can reach 0.4% and higher. I obviously advise labs and medical review officers to do a glucose dipstick test before reporting alcohol to any of their clients, as MROs and labs have both been sued on this issue. So the important takeaway from this slide is actually the bottom bullet, the uncontrolled diabetics. And now I'm going to move to several slides that cover the pharmacokinetics and would be important for you taking the exam. These bullets deal with alcohol absorption. All alcohol is generally absorbed within 30 to 60 minutes. It's slowed by food. It's increased by carbonated drinks, for example, champagne and beer. There is an important enzyme in the gastric wall. It's gastric alcohol dehydrogenase and that metabolizes alcohol. Women have 50% less of that than men, which obviously leads to increased absorption for women and male alcoholics have 50% more of that compared to non-alcoholic men. That again leads to decreased absorption. So GAD is an important enzyme for the absorption of alcohol from the gastric tract. Our next slide deals with distribution of alcohol. Alcohol is distributed in body water. Men have more of that than women. Therefore, women will have higher blood alcohol concentrations for two reasons over men and that is the GAD enzymes I talked about on the prior slide and the alcohol distribution in body water. There is a formula that can be used to estimate peak blood alcohol concentration if the amount of alcohol consumed is known. It's called Wittmark's formula. Wittmark was a Swedish chemist early in the 20th century. Some experts would take a blood alcohol, back calculate that blood alcohol based on the elimination rate to get a blood alcohol, for example, at a time of an accident. They'll then use that blood alcohol at the time of the accident to calculate the amount of alcohol consumed through Wittmark's formula. I recommend strongly against that. There is very little certainty in either of those calculations. One, the elimination rate has a range as I've mentioned and Wittmark's formula requires weight or body mass to determine the amount of alcohol which is variable. So I certainly recommend against making calculations like that. Our next slide is going to talk about distribution in body fluids which is important because it does cover some aspects of the DOT drug testing program. I only want to talk about three of the numbers on this slide. Obviously blood has been set as a one because that's the point of reference and as you can see saliva is about 1.1 with a range of 0.97 to 1.4. So saliva is a very good estimator of blood alcohol concentration and as Dr. Smith mentioned is included in the DOT alcohol testing program. The next number I want to mention is the urine number. I mentioned earlier there's a distribution factor of 1.3 but the range is considerable 0.21 to 2.65. So one of the reasons why urine has fallen out of favor as a fluid for estimating blood alcohol concentrations is this range as well as the detailed collection procedures needed. And the final number I want to look at is the bottom number which is 1 to 2100 and that is Henry's law if you remember from your chemistry physics education. Distribution of a element or a chemical between liquid and vapor phase and that ratio is the ratio used to standardize the breath alcohol instruments that Dr. Smith referred to. So our next slide is going to talk about the metabolism of alcohol. Alcohol is heavily metabolized. It's metabolized by alcohol dehydrogenase and then by aldehyde dehydrogenase. Some people are deficient in aldehyde dehydrogenase and therefore build up aldehyde levels which causes toxic side effects. And we've talked about enzyme saturated kinetics but there are factors that can impact the metabolic rate. Smoking for example will increase it. Use of oral contraceptive and H2 antagonists will decrease it. And most importantly chronic use will increase it due to activation of P450 systems. By chronic use I'm referring to blood alcohols that could be 0.3, 0.4 that will kick in the P450 systems and then the kinetics of alcohol elimination will not be zero order. It's an important factor for those of you who deal with the alcoholic community because they do have several different ways of metabolizing the alcohol and eliminating the alcohol. And that's what we're going to talk about next alcohol elimination. You can see from the first bullet of the 1% unchanged very little is eliminated in the breath. So certainly it's an important factor breath elimination but it does not eliminate much of the alcohol absorbed. And again re-emphasizing the saturation kinetics of 0.018% per hour. And our next slide is on breath-blood ratio and we're going to talk. Some states and some countries use breath alcohol as the per se and not blood alcohol as the per se. As you can see from the second bullet Henry's law is one milliliter of blood equals 2100 milliliters of air. There's some biological variation in that ratio as there's in every ratio and you can see that it's 1 to 1250 to 1 to 2800 approximately. Some defense attorneys in DUI cases will actually determine that the number the variation and the actual ratio of the defendant to argue that the blood alcohol calculation in the breath instrument was incorrect. That can be overcome for by using this breath alcohol as the per se and there is a movement I think that will continue to do that in this country and other parts of the country. The third bullet just shows you that 0.1% equals one milligram per milliliter of blood and one milligram per 2100 milliliters of air. So finally in this particular point of alcohol I'm going to talk about alcohol concentration units. I'm not going to spend long on this slide but if I was taking an MRO certification exam I certainly would highlight it. It shows you variations from weight per volume to milligram per mil to milligram per decaliter etc and you could imagine a question or two built around those numbers. So if I was taking the exam I would certainly highlight this slide. My final slide is on biomarkers and I'm going through this slide for those of you who might be involved in the rehab business because these are important numbers given the increase in the use of monitoring ethanol glucuronide and ethanol sulfate. So next slide is on those particular biomarkers. When ethanol glucuronide was introduced as an alcohol biomarker there was some concern because the use of cough medicines etc that had low amounts of alcohol caused positive ethanol glucuronide findings in urine and what SAMHSA has done is produced some guidelines for the interpretation of those ethanol glucuronide results. Now I'm not going to go through them bullet by bullet. If you're in this business you know about this I hope and if you're not these are for information purposes. So in summary I've done a quick overview of ethanol slash alcohol in terms of its pharmacokinetics, the interpretation of the results and I think I have struck and hope I have struck the most important points in these slides if you are taking the exam. Thank you very much.

alcohol testing

toxicology

blood alcohol concentration

legal limits

biomarkers