Forensic Toxicology Lecture Notes Flashcards

Thirty QA flashcards covering key concepts from chapters on postmortem toxicology, alcohol metabolism, and breath/alcohol testing.

What are the two main categories of forensic toxicology?

Postmortem toxicology and human performance toxicology.

What does a postmortem toxicology investigation seek to determine?

Whether poisons or drugs contributed to death by analyzing substances in body fluids and organs.

What does human performance toxicology measure?

The amount of alcohol or drugs in a living person and their role in modifying performance or behavior.

What does a postmortem toxicology laboratory typically analyze?

Prescription drugs, drugs of abuse, chemical products and gases.

What elements are included in the case history for the deceased?

Age, sex, weight, medical history, medications, autopsy findings, drugs available to the decedent, and interval between onset of symptoms and death.

Why should specimens be collected before embalming?

Embalming may destroy poisons and the alcohols in embalming fluid may confound sobriety readings.

Name the tissues and fluids listed as high-interest for toxicologists.

Brain (50 g), liver (50 g), kidney (50 g), heart blood (25 mL), peripheral blood (10 mL), vitreous humor, bile, urine, and gastric contents.

What unusual sources can help in advanced decay?

Bone marrow in skeletal remains and maggots; vitreous humor is resistant to decay.

What is the role of presumptive tests like immunoassays?

Screen for drug classes; a positive result leads to confirmation testing.

What method is used for confirmation after a positive immunoassay?

Gas chromatography–mass spectrometry (GC-MS).

How does GC-MS identify compounds?

GC separates compounds; MS fragments molecules and the spectra are matched to a library.

Which instrument is used to screen for metals in samples?

Inductively coupled plasma optical emission spectroscopy (ICP-OES).

What are metabolites and why are they important in toxicology?

Metabolites are breakdown products of drugs; agencies know which metabolites are produced by which drugs.

How is the minimal administered dose estimated from organ data?

Multiply each tissue’s concentration by its weight and sum across all organs.

What does 'per se' mean in DUI law?

A BAC at or above a prescribed level is conclusive evidence of intoxication.

What was a major outcome of the Grand Rapids study?

Validated the breathalyzer and established the per se concept for DUI laws.

What BAC is considered sober according to the notes?

Up to 0.06% BAC.

What BAC limit is set for commercial drivers?

0.4% BAC.

When did the Department of Transportation push for an 0.08% BAC limit, and what was the enforcement timeline?

The 1992 recommendation; states were given a deadline (by 2003) to adopt the limit to avoid federal funds.

Which countries are cited as using an 0.8% BAC limit (as noted in the text)?

Canada, Japan, Italy, Switzerland, and the United Kingdom (noted as 0.8%, commonly written as 0.08%).

What is the GI absorption distribution for alcohol?

Approximately 20% absorbed in the stomach and 80% in the small intestine.

What factors influence the rate at which ethyl alcohol enters the bloodstream?

Rate of gastric emptying, presence of food, alcohol concentration, beverage type, and rate of consumption, plus GI-acting drugs.

How does eating with alcohol affect peak BAC and clearance?

Food delays gastric emptying, lowers peak BAC, and speeds clearance; a full stomach slows absorption.

What is back extrapolation in BAC calculation?

Estimating the BAC at the time of the accident using known absorption and elimination rates after the fact.

What is Henry’s law ratio used in breath testing?

At body temperature, the blood to alveolar air ratio for alcohol is about 2000:1 (roughly 1 mL blood equals ~2100 mL breath).

Who invented the breathalyzer and when?

Robert Borgenstein in 1954.

What technologies have largely replaced the traditional breathalyzer?

Infrared-based Intoxalizer and alcohol fuel-cell (Alco Sensor) breath testers.

What substances can cause false positives in IR breath tests?

Acetone, acetaldehyde, toluene (e.g., acetone from nail polish remover, toluene from paints, acetaldehyde from cigarette smoke).

How does the Alco Sensor fuel cell measure BAC?

Alcohol oxidized at a platinum layer produces electrons; the current is proportional to alcohol and converted to BAC.

What noninvasive method measures alcohol on the skin, and how long does it take?

Near-infrared reflectance spectroscopy on the forearm; about 90 seconds.