FRSC 1011H Chapter Notes - Chapter 12: Ethanol, Toxicology, Nystagmus
2 May 2018
School
Department
Course
Professor
Forensic Toxicology
Role Of Forensic Toxicology
● Forensic toxicologists detect and identify drugs and poisons in body fluids,
tissues, and organs in situations that involve violations of criminal law.
● Ethyl alcohol is the most heavily abused drug in Western countries.
Toxicology of Alcohol
● Alcohol appears in the blood within minutes after it has been taken by mouth. It
slowly increases in concentration while it is being absorbed from the stomach
and the small intestine into the bloodstream.
● When all the alcohol has been absorbed, a maximum alcohol level is reached in
the blood, and the posyansorption period begins. During postabsorptive, the
alcohol concentration slowly decreases until a zero level is reached.
● Elimination of alcohol throughout the body is accomplished through oxidation and
excretion. Oxidation takes place almost entirely in the liver, whereas alcohol is
excreted unchanged in the breath, urine, and perspiration.
● Breath-testing devices operate on the principle that the ratio between the
concentration of alcohol in alveolar breath and its concentration in blood is fixed.
Testing For Intoxication
● Modern breath testers are free of chemicals. They include infrared light
absorption devices and fuel cell detectors.
● The key to the accuracy of a breath-testing device is to ensure that the unit
captures the alcohol in the alveolar (deep-lung) breath of the subject.
● Many breath testers collect a set volume of breath and expose it to infrared light.
The instrument measures the concentration of alcohol in the collected breath
sample by measuring the degree of interaction between the light and the alcohol
present.
● Law enforcement officers use field sobriety tests to estimate a motorist’s degree
of physical impairment from alcohol and to determine whether an evidential test
for alcohol is justified.
● The horizontal-gaze nystagmus test, the walk and turn, and the one-leg stand are
all considered reliable and effective psychophysical tests for alcohol impairment
Document Summary
Forensic toxicologists detect and identify drugs and poisons in body fluids, tissues, and organs in situations that involve violations of criminal law. Ethyl alcohol is the most heavily abused drug in western countries. Alcohol appears in the blood within minutes after it has been taken by mouth. It slowly increases in concentration while it is being absorbed from the stomach and the small intestine into the bloodstream. When all the alcohol has been absorbed, a maximum alcohol level is reached in the blood, and the posyansorption period begins. During postabsorptive, the alcohol concentration slowly decreases until a zero level is reached. Elimination of alcohol throughout the body is accomplished through oxidation and excretion. Oxidation takes place almost entirely in the liver, whereas alcohol is excreted unchanged in the breath, urine, and perspiration. Breath-testing devices operate on the principle that the ratio between the concentration of alcohol in alveolar breath and its concentration in blood is fixed.
