Chapter 13 Forensic Toxicology

Forensic toxicologists

are responsible for detecting and identifying the presence of drugs and poisons in body fluids, tissues, and organs

identify a drug overdose or monitor the intake of drugs.

Forensic toxicologists not only work in crime laboratories and medical examiners’ offices, but may also reach into hospital laboratories and health facilities to…

measurement of alcohol

A major branch of forensic toxicology deals with the ________ in the body for matters that pertain to violations of criminal law.

the detection and isolation

The analysis of alcohol exemplifies the primary objective of forensic toxicology: ________ of drugs in the body for the purpose of determining their influence on human behavior.

colorless liquid

Alcohol, or ethyl alcohol, is a ________ normally diluted with water and consumed as a beverage.

the most heavily abused legal drug

Alcohol is ________ in Western countries.

• About 10,900 traffic deaths each year are attributed to alcohol intoxication.

brain.

Like any depressant, alcohol principally affects the central nervous system, particularly the…

Blood alcohol concentration

has been shown to be directly proportional to the concentration of alcohol in the brain.

Alcohol’s Fate in the Human Body

• Absorption

• Distribution

• Elimination

the stomach and the small intestine into the bloodstream.

Alcohol appears in the blood within minutes after it has been taken by mouth and slowly increases in concentration while it is being absorbed from…

post-absorption or elimination period begins.

When all the alcohol has been absorbed, a maximum alcohol level is reached in the blood; and the…

30-90

For an average human drinking on an empty to modestly full stomach, alcohol is absorbed entirely into the blood stream ________ minutes after the completion of drinking.

2-3

When drinking on a full stomach, the absorption time can be as long as ________ hours.

carbohydrates

The type of beverage also affects absorption time. For example, beer is absorbed more slowly than 80 proof alcohol because of the ________ in beer.

lower

The longer the time for complete absorption to occur, the ________ the

peak alcohol concentration in the blood.

uniformly distributed

When absorption is complete, alcohol becomes ________ between all the watery portions of the body, which is about two-thirds of body volume.

be used to determine alcohol levels.

In decedents, if blood is not available, other watery portions of the body, e.g., brain, cerebrospinal fluid, or vitreous humor, can…

oxidation and excretion.

Elimination of alcohol throughout the body is accomplished through…

liver

Oxidation takes place almost entirely in the ________, where the enzyme alcohol dehydrogenase converts alcohol to acetic acid and then into carbon dioxide and water.

5%

About ________ of the alcohol is excreted unchanged in the breath, urine, and perspiration.

percent weight per volume.

Blood alcohol concentration is defined as…

0.015%/hour

The elimination or “burn-off” rate of alcohol varies, but ________ seems to be a reasonable average.

measuring the quantity of alcohol present in the blood system or by measuring the alcohol content in the breath.

The extent to which an individual may be under the influence of alcohol is usually determined by either…

True

The amount of alcohol exhaled in the breath is in direct proportion to the blood concentration and is directly proportional to alcohol in the brain.

0.08

The current legal measure of drunk driving in the United Stated is a blood-alcohol concentration of ________ percent,

34°C

The temperature at which the breath leaves the mouth is normally ________.

2,100 to 1

Breath testers operate on the fact that at 34°Celsius, the ratio of alcohol in the blood to alcohol in alveolar breath is approximately ________.

infrared light absorption

Breath testers that operate on the principle of________ are becoming increasingly popular within the law enforcement community.

flows through a chamber in the breath tester and is exposed to infrared radiation to measure a blood-alcohol concentration in breath.

Many types of breath testers are designed to analyze an individual’s breath as it…

A portable, handheld, roadside breath tester

may be used to determine a preliminary breath-alcohol content.

Portable Breath Testers (PBT)

use fuel-cell detectors and are not admissible in court proceedings as proof of intoxication.

field sobriety

Law enforcement officers typically use ________ tests to estimate a motorist's degree of physical impairment by alcohol and whether or not an evidential test for alcohol is justified.

horizontal gaze nystagmus

The ________ test, walk and turn, and the one-leg stand are all considered reliable and effective psychophysical tests.

Gas chromatography

offers the toxicologist the most widely used approach for determining alcohol levels in blood in forensic labs.

They measure the conversion of alcohol to acetaldehyde by alcohol dehydrogenase.

Why do hospital or clinical labs normally use autoanalyzers to measure alcohol content?

True

Blood must always be drawn under medically accepted conditions by a qualified individual.

nonalcoholic disinfectant

A ________ must be applied before the suspect's skin is penetrated with a sterile needle or lancet.

anticoagulant and a preservative

Once blood is removed from an individual, the best way to preserve it is to seal it in an airtight container that contains an ________. Then store the sample in a refrigerator.

a decline of the blood alcohol level.

Failure to properly preserve blood removed from living individuals may result in…

elevated blood alcohol level.

In decedents, alcohol may be produced during decomposition, creating an…

per se laws

All 50 states have established ________, meaning that any individual at a defined blood alcohol concentration (normally 0.08%) shall be deemed to be intoxicated.

4, 25

At 0.08% a driver is ________ times more likely to become involved in an accident. At 0.15% the chances rise to ________ times.

implied consent

To prevent a person’s refusal to take a test for alcohol consumption, all the states have adopted an “________” law.

either consent to a test for alcohol intoxication, if requested, or lose his or her license for some designated period.

The implied consent law states that the operation of a motor vehicle on a public highway must…

PA

• 12 months first time, 18 months second

• Under 21: <0.02%, $100 fine, 3 month suspension

• >0.02%: 48 hours jail, $5000 fine, education

NJ

• 7 months first time, 2 years second time

• Under 21: <0.01%, $500 fine, 1-3 month suspension, probationary license, community service, education

• >0.08%: charged as an adult

DE

• 0.05-0.08%, 1 year first time, 60-80 days jail second

• Under 21: <0.02%, $200 fine, 2 years

• >0.08%: suspended until 21

drugs and poisons.

Beyond the analysis of alcohol, the toxicologist is confronted with a maze of ________.

body fluids and/or organs

The toxicologist is presented with ________ and is normally requested to examine them for the presence of drugs and poisons.

general screening procedures

Without supportive evidence, such as the victim’s symptoms, a postmortem pathological examination, or an examination of the victim’s personal effects, the toxicologist is forced to use ________ with the hope of narrowing thousands of possibilities to one.

anything consumed has been dissipated and distributed throughout the body.

Also, the toxicologist is not dealing with drugs at the concentration levels found in powders and pills, since…

body

The ________ is an active chemistry laboratory, as few substances enter and completely leave the body in the same chemical state.

metabolized

Many drugs are chemically changed or are ________ in the body to different chemical substances.

the toxicity of the drug or poison.

When and if the toxicologist has surmounted all of these obstacles, he or she must be prepared to assess ________.

be devoted to their extraction and detection.

Because drugs constitute a large portion of the toxic materials found by toxicologists, much of effort must…

acids and bases.

Many drugs fall into the categories of…

acid

An ________ is capable of donating a hydrogen ion.

• Barbiturates, aspirin

base

A ________ is capable of accepting a hydrogen ion.

• Cocaine, amphetamines, methadone

pH scale

Acidity and basicity are measured by the ________.

This approach gives the toxicologist a general technique for extracting and categorizing drugs.

By controlling the pH of a water solution into which blood, urine, or tissues are dissolved, the toxicologist can conveniently control the type of drug that is recovered.

Screening, Confirmation

The strategy used for identifying abused drugs entails a two-step approach:

A screening test

is normally employed to provide the analyst with quick insight into the likelihood that a specimen contains a drug substance.

tentative

Positive results arising from a screening test are considered to be ________ at best and must be verified with a confirmation test.

gas chromatography (GC) and immunoassay

What are the most widely used screening tests?

True

Gas chromatography/mass spectrometry is generally accepted as the confirmation test of choice.

fingerprint

The GC separates the sample into its components, while the MS represents a unique “________” pattern that can be used for identification.

urine drug testing

Typically for a living person, it’s the blood that is tested for drug content; however, ________ for drugs is becoming common for jobs and employees in the work place.

Hair

is nourished by blood flowing through capillaries located close to the hair root.

permanently trapped in the hair’s hardening protein structure.

Drugs present in blood diffuse through the capillary walls into the base of the hair and become…

hair shaft

As the hair grows, the drug’s location on the ________ becomes a historical marker for delineating drug intake.

one

Human hair grows around ________cm/month

Detecting Nondrug Poisons

Heavy metals such as arsenic, bismuth, antimony, mercury, and thallium may be encountered.

Carbon monoxide

prevents the normal transport of oxygen throughout the body.

50-60%

In a healthy, middle-aged individual, a carbon monoxide blood saturation greater than ________ is considered fatal.

provide an opinion on the drug's effect on an individual's natural performance or physical state.

Once the drug is extracted and identified, the toxicologist may be required to…

estimate the pharmacological effects of the drug on the individual.

For many drugs, blood concentration levels are readily determined and can be used to…

poor

The concentration of a drug in urine is a ________ indicator of how extensively an individual's behavior or state is influenced by the drug.

age, health, and tolerance.

Before drawing conclusions about drug-induced behavior, the analyst must consider other factors including…

observed about an individual's behavior and motor skills.

Often, regarding a living person, the toxicologist has the added benefit of knowing what a police officer may have…

Los Angeles Police Department

During the 1970s, the ________ developed clinical and psychophysical examinations that a trained police officer could use to identify and differentiate between types of drug impairment.

drug recognition experts.

The LAPD program has evolved into a national program to train police as…

three- to five-month

Normally, a ________ training program is required to certify an officer as a drug recognition expert (DRE).

The DRE program

incorporates standardized methods; e.g., blood pressure, pulse, or pupil size, for examining suspects to determine whether they have taken one or more drugs.

each DRE must complete a standard Drug Influence Evaluation form.

To ensure that each subject has been tested in a routine fashion…

cannot

The DRE program usually ________ determine which specific drug was ingested.

the DRE and the forensic toxicologist

it is the production of reliable data from both ________ that is required to prove drug intoxication.