Forensic Toxicology 1. Toxicologist look for the presence or absence of drugs and poisons in the bodies fluids and organs.

2. Toxicologist work for crime labs and medical examiners offices 2. Toxicologist work for crime labs and medical examiners offices. They also work for hospitals and other health facilities.

A. TOXICOLOGY OF ALCOHOL 1. Alcohol is the most widely abused drug in Western countries. In the U.S. 12,500 automobile deaths (40%) are alcohol related, with 2 million people per year hospitalized from injuries.

B. What happens to alcohol in the body? 1. There are many factors that must be taken into account when considering the effects of alcohol on a person.

2. Alcohol is a depressant that effects the central nervous system, especially the brain. 3. The extent of the depression is directly proportional to the concentration of alcohol within the nerve cells.

The first part of the brain to be effected is the forebrain (movement, behavior, emotion, problem solving). Then the central (orientation, visual processing) and rear portions (memory, perception) are effected.

Last is the medulla region Last is the medulla region. This is the area responsible for controlling breathing and heart function.

4. How can you determine how much alcohol is effecting an individual? It is the blood that distributes the alcohol around the body

5. Blood-alcohol concentration is directly proportional to the alcohol concentration of alcohol in the brain.

6. Alcohol is absorbed from the stomach and intestine minutes after being ingested. When all the alcohol has been absorbed the maximum level is reached. Then the post absorption period begins and the alcohol concentration level drops to zero again.

7. Several factors influence the rate at which alcohol is absorbed including: Total time taken to consume alcohol. Amount of alcohol consumed. Quantity and type of food in the stomach.

8. During the absorption phase blood distributes the alcohol throughout the body. When the absorption phase is complete the alcohol is distributed evenly throughout the watery parts of the body (2/3 of it).

9. The body begins to rid itself of alcohol shortly after it is absorbed. Elimination is accomplished by 2 mechanisms – oxidation and excretion.

10. Oxidation is the combination of oxygen with other substances to produce new products. 95 to 98% of the alcohol is oxidized into CO2 and H2O. Oxidation happens in the liver.

12. The rest of the alcohol is excreted in the breath, urine, and sweat. The amount of alcohol exhaled is directly proportional to the concentration of alcohol in the blood. This fact has led to the development of test that confirm alcohol content.

C. Alcohol in The Circulatory System. 1. Remember humans have a closed circulatory system consisting of heart, arteries, capillaries, and veins. Arteries carry blood away from the heart.

Veins carry blood toward the heart Veins carry blood toward the heart. Capillaries are very small vessels connecting arteries and veins. Diffusion happens in the capillaries.

2. After alcohol is consumed it moves down the esophagus into the stomach. About 20% of the alcohol is absorbed through the stomach wall into the blood system.

The remaining alcohol passes into the blood through the walls of the small intestine. Once in the blood the alcohol is carried through the liver to the heart. Blood enters the upper right atrium then is forced into the right ventricle.

Then to the lungs where CO2 can be exchanged f0r O2 Then to the lungs where CO2 can be exchanged f0r O2. The pulmonary artery branches into capillaries that are very close to the alveoli (small sacs in the lungs through whose walls air is exchanged between breath and blood).

There are about 250 million alveoli in the lungs There are about 250 million alveoli in the lungs. They are connected to the bronchial tubes that are connected to the trachea (windpipe).

If there is alcohol in the blood it will be exchanged with the CO2 for O2 and exhaled. The freshly oxygenated blood is taken back to the left atrium then to the left ventricle then into arteries which distribute blood throughout the body.

These arteries pass into smaller ones then into capillaries These arteries pass into smaller ones then into capillaries. It is h ere that the alcohol in the blood diffuses into the tissues.

D. Breath –Test Instruments 1. The breathalyzer is used to determine the amount of alcohol in the breath. The air that is trapped in the machine is combined with potassium dichromate, sulfuric acid and water.

The alcohol dissolves into the potassium dichromate and is oxidized into acetic acid. In this oxidation process the potassium dichromate is destroyed. The amount that is destroyed is proportional to the amount of alcohol present.

2. Field Sobriety Tests are normally performed to ascertain the degree of the suspect’s physical impairment and whether or not other test are needed.

a. Horizontal Gaze Nystagmus – the involuntary jerking of the eye as it moves to the side. A person experiencing nystagmus is unaware of the jerking and unable to stop or control it.

They are asked to follow an object with their eyes as far as they can They are asked to follow an object with their eyes as far as they can. With a blood-alcohol level of 0.10 percent the jerking motion will begin around 45 degrees. Higher blood-alcohol content and the jerking begins at smaller angles.

b. The walk-and-turn requires walking heel-to-toe for nine steps then turning and repeating the process.

C. The one-leg stand requires the suspect to maintain balance while standing with heels together then standing with one foot off the ground balancing on the other and counting to 30.

E. The analysis of blood for alcohol 1. Gas chromatography can be used on blood samples to determine the alcohol level in blood.

F. Collection and Preservation of Blood 1. Once blood is removed from an individual it should be kept in a sealed air-tight container after an anticoagulant and preservative are added.

The anticoagulant keeps the blood from clotting and the preservative stops the growth of microorganisms.

G. Alcohol and the Law 1. In 1992 the U.S. Department of Transportation recommended that states adopt a 0.08 percent blood-alcohol concentration as the legal measure of drunk driving.

If states chose not to adopt this level they will lose Federal funds for highway construction. For commercial truck drivers the limit is 0.04.

2. Can a person refuse to take a test for alcohol levels?

Yes. In 1973 states adopted an “implied consent” law Yes. In 1973 states adopted an “implied consent” law. This law says the operation of a motor vehicle on a public road automatically carries with it the stipulation that the driver will have the choice of either submitting to a test or be subject to losing their license.

3. The 5th Amendment refers to self-incrimination. In Schmerber v 3. The 5th Amendment refers to self-incrimination. In Schmerber v. California the Supreme Court ruled that the 5th Amendment applies only to testimonial evidence and not to physical evidence such as fingerprints, DNA, and blood samples.

H. The Role of the Toxicologist 1. How does the toxicologist go about determining the toxin or poison in a sample? First they look for clues in personal effects like pill bottles, containers etc. If these are not available they begin a screening process.

They must use samples that have been extracted from bodily fluids and organs for testing. The amounts of the drugs may be very small (nanograms or micrograms).

Another problem toxicologist face is that most drugs change to something else when they enter the body because they are metabolized.

I. Techniques Used in Toxicology 1. The process of extracting a drug from a biological specimen is complex. 2. Most drugs fall into categories of acids or bases.

An acid is a compound capable of donating a hydrogen ion to another compound. A base is a compound capable of accepting a hydrogen ion. Acids and bases are measured on a pH scale.

The pH scales goes from 0 to 14. A pH of 7 is neutral. Below 7 is acidic with 0 being the most acidic. Above 7 is basic with 14 being the most basic.

By controlling the pH of a water solution into which a sample is dissolved the toxicologist can tell if the extracted drug falls into the acid or base categories.

3. Then they begin the process of screening and confirmation. The three most widely used screening tests are Thin-layer chromatography Gas chromatography Immunoassay

Immunoassay is a process based on specific drug antibody reactions Immunoassay is a process based on specific drug antibody reactions. Its primary advantage is its ability to detect small concentrations of drugs in body fluids and organs.

Gas chromatography/mass spectrometry is the most commonly used method of confirming a drug.

4. Forensic toxicologist also must test for heavy metals 4. Forensic toxicologist also must test for heavy metals. These include arsenic, bismuth, antimony, mercury, and thallium. This is done by dissolving the sample in hydrochloric acid and inserting a copper strip.

If a silvery or dark coating appears on the strip it indicates the presence of a heavy metal. This is called the Reinsch Test.

Another poison frequently encountered is carbon monoxide Another poison frequently encountered is carbon monoxide. When it enters the body it is absorbed by the red blood cells where it combines with hemoglobin to form carboxyhemoglobin.

An average red blood cell contains about 280 million molecules of hemoglobin. The hemoglobin is what carries oxygen around the body to the tissues.

If a high percentage of hemoglobin is carrying carbon monoxide instead of oxygen death by asphyxiation will occur. The amount of carbon monoxide in blood is expressed as percent saturation.

This represents the extent to which the available hemoglobin has been converted to carboxyhemoglobin. A level of 50 – 60 percent is usually fatal. A level of 35 – 40 percent may be fatal if the blood-alcohol level is elevated.

Suicide by automobile is common. Carbon monoxide levels are also measured in victims of fires. The presence of high levels of carbon monoxide in the blood indicated they were alive when the fire began. Absence means?

Common poisons and their symptoms. Arsenic, mercury, copper, metals; severe unexplained diarrhea, vomiting Atropine; dilated pupil of the eye Carbon monoxide; skin is bright cherry red

Cyanide; quick death, red skin, odor of peaches. Food poisoning; vomiting, abdominal pain Nicotine; convulsions Strychnine; convulsions, dark face and neck

There are about 700 deaths by poisoning reported each year. Children under 6 account for the majority of poisons reported but adults account for the majority of deaths.