Forensic Toxicology Alcohol absorption Unit 3 Dr. Gray JANUARY 2016

Toxicology Alcohol, ethyl alcohol, has a very rapid absorption time as it becomes concentrated in the blood following ingestion. The absorption of alcohol takes places predominatly in the stomach and the small intestine. When alcohol is consumed, it occupies all of the high water contents of the body which is approx. 2/3 of the body. Alcohol reaches a maximum concentration in the blood wich is refered to as the post-absorption phase.

Toxicology Fat, bones, and hair (which are not high in water content) would have a lower concentration of alcohol then the rest of the body. There are several important factors which influence the rate of alcohol absorption. These include: A) The time taken to consume the alcohol. B) The content of alcohol. C) The quantity of alcohol ingested. D) The amount of food present in the stomach at the time of alcohol ingestion

Toxicology As alcohol begins to circulate through the bloodstream, it begins to undergo elimination. There are two methods of elimination: A) oxidation B) excretion

Toxicology When the body eliminates alcohol in an unchanged chemical state, this is refered to as excretion. Excretion may take the form of breathing or urination. If the alcohol is chemically altered at the time of elimination than it has undergone oxidation.

Toxicology Most of the alcohol which is consumed is chemically oxidized to two important products. These include carbon dioxide and water. Oxidation takes place in the liver with the help of the enzyme alcohol dehydrogenase. Alcohol is first converted to acetaldehyde and then to acetic acid. The acetic acid is further oxidized in almost all parts of the body to carbon dioxide and water.

Toxicology The remaining alcohol undergoes excretion- elimination from the body in an unchanged chemical state. The alcohol which is excreted through the lungs, is a direct measure of the concentration of alcohol in the blood.

Toxicology On average it takes 30 to 90 minutes for the alcohol to reach its peak absorption into the blood following the last alcoholic beverage which is consumed by an individual. A toxicologist may analyze the level of alcohol content within an individual knowing the time of absorption and where alcohol tends to collect within the body (water abundant organs and tissues).

Toxicology There are two methods which a toxicologist may use for meausring alcohol-blood content. These include: 1) a blood test 2) a breath test

Toxicology The absorption and elimination of alcohol in the blood vessels follows the same general path as bloodflow. Special cases exist in the lungs. Particularly at level of the alveolar sacs in the lung.

Toxicology Field Sobriety Testing These test are designed to challenge an individual’s psychological and physical abilities. – Roadside breath tester – (uses a fuel cell to check for the sobriety of an individual) – Lateral gaze nystagmus, standing on one foot, walk and turn.

Toxicology With respect to the lateral gaze nystagmus, there would be a greater degree of nystagmus (but at a smaller angle) prior to the individual tracking a pen light-for example. Certain drugs may also cause an early onset of the nystagmus then others – Barbituates – Other depressants

Toxicology There is also the inclusion of multi-attention tasks which challenge the individual’s to comprehend and perform several different tasks at once will become increasingly difficult with an increase in alcohol consumption. Often these include bth standing on one leg for thirty seconds and walking heel-to-toe for a distance of nine feet.

Toxicology Toxicologists may use two different methods for the analysis of blood alcohol levels: These include GAS CHROMATOGRAPHY The enzyme alcohol dehydrogenase and cofactor NAD The latter method is based on the extent of oxidation of NAD to NADH.

Toxicology Preservation and taking of blood. Blood must be drawn from qualified healthcare personel and the use of proper disinfectant in the area of the bood draw is crucial. The disinfectant should be free of alcohol content as to not interfere with the results of the toxicologist.

Toxicology Mercuric chloride or povidone-iodine are recommended agents to ensure the integrity of the area of the blood draw. Any blood sample removed from a suspect must be anticoagulated and have the addition of a preservative-such as sodium fluoride. The sodium fluoride helps prevent the colonization of blood by harmful microorganisms.

Toxicology In addition to the proper maintenance of the blood-preventing coagulation (with EDTA), and preserving the blood, the use of refrigeration is also very important for the proper environment of a sample until it may be delivered to a toxicologist.

Toxicology Postmortem samples of blood require special attention. These include: – The natural production of alcohol by microorganisms in the deceased. – Additional fluid specimens should be obtained from both the vitreous humor and urine-these fluids will not undergo the same bacterial decomposition as the blood.

Toxicology Postmortem blood samples require the same attention to the inclusion of an anticoagulant and preservative as with a living subject’s blood-just much more care and attention is required as to not cause any destruction of the sample.

Question 1 What are some procedures which are done by a medical examiner in the collection of evidence from the deceased?

Question 2 From the assigned reading, what is the signifigance of the Supreme Court’s ruling in Schmerber v. California?

Toxicology Why was the need for a court order overruled in the case Schmerber v. California?