Forensic Toxicology

Toxicology is the combination of chemistry and physiology that deals with drugs, poisons, and other toxic substances and how these substances effect living organisms.

Drugs and toxic chemicals span a massive range from alcohol (which is socially acceptable) to heroin and crack cocaine (which are generally frowned upon) and on to killers, including arsenic and cyanide that are used only as tools of aggression or suicide.

So, what poisons have you ingested today?

Perhaps a little oxygen?

Maybe a little water?

How about a little ricin or some arsenic

with your meal? Would you like a side of hemlock?

It’s all in the doseThe degree of toxicity of any substance depends on how much enters your body and over what period of time it does so.

Have you ever walked into a bar and the bartender says to you, “So, name your poison”?

No, you haven’t. You’re too young!

Stop laughing.

Toxicology plays a part in forensics at three levels:

1. A criminalist may be asked to see if a person’s behavior has been influenced by a drug.

2. A forensic team may examine evidence to see whether a suspect has been manufacturing illicit compounds.

3. Forensic experts will look for evidence that a toxic substance has killed a person.

Now, we need to get into the

nitty gritty of toxicology…

Intoxicant vs. Poison

An intoxicant, such as alcohol or carbon monoxide, requires that you ingest a large amount to be lethal.

A true poison, such as cyanide, requires only a very small amount.

The Father of Toxicology was a guy named Mathieu Orfila. His work was mainly centered on arsenic; the poison of choice in the early 1800’s. It was readily available in rat poison and was the favorite means of murder among the poor people.

James Marsh (1836) developed a test which was very sensitive for detecting arsenic. It is still taught to forensic science students but really is not used too much because of more advanced tests available.

So, what does James Marsh have to do with Napoleon’s wallpaper?

The Marsh Test

It has been suspected for years that Napoleon’s death was caused by arsenic poisoning. Arsenic loves to bind to sulfur and there is plenty of sulfur in your hair so basically your hair is a timeline for many poisons with the same habit. There is one fact…arsenic was found in Napoleon’s hair.

So….the story of Napoleon’s wallpaper really began in 1980 when Dr. David Jones, a chemist in Newcastle, UK was making a radio broadcast. He was really wondering who was listening and asked the question, “Who knows the color of Napoleon’s wallpaper on St. Helena?” The subject of the program was chemical vapors.

Jones had known that some people who had been exposed to arsenic would get sick and die but weren’t necessarily poisoned. In 1893 an Italian Biochemist named Gosio figured out that the green pigment used in many fabrics and wallpapers contained an arsenic compound that when exposed to dampness would emit arsenic vapors. People living in the home would gradually become sick and die as did Napoleon’s butler.

So, was there an answer to Jones’ radio question?

Of course, why else would I even bring up this story?

So, a women named Shirley Bradley from Norfolk, UK contacted Jones and said that she had a scrapbook page made from the wallpaper of Napoleon’s bedroom on St. Helena. Sure enough, the page was tested (using the Marsh test) and arsenic was detected. Jones himself made the trip to St. Helena and confirmed that this was indeed the same paper.

Next to the scrap of wallpaper, the old fashioned copper-plate handwriting reads:

'This small piece of paper was taken off the wall of the room in which the spirit of Napoleon returned to God who gave it'.

So, the next question was, “Why then didn’t everyone at St Helena die of arsenic poisoning?

Jones came up with the conclusion that there wasn’t enough arsenic to bring all healthy people to their death but Napoleon was already sick with an ulcer and was confined to his bedroom, often with the shutters closed. He was moved to the drawing room shortly before his death to get him away from the damp, ‘bad air’ that had consumed his bedroom for months.

An engraving was made of the scene in the drawing room, with everyone around the death bed. The engraving is supposed to be an extremely accurate likeness of everyone that was present. The nearest thing to a photograph that could be created in 1821. The image shown here is only a low resolution scan, but if you look closely at the engraving itself you can see that the back wall of the drawing room has wallpaper on it. And on that wallpaper there is a pattern of stars...

Looking for Poisons

Most poisons don’t visibly change the body. The medical examiner won’t notice poisoning in most cases until fluids and tissue samples are examined in the lab.

Biotransformation

No… This is not a Frankenstein experiment.

Biotransformation

When a chemical enters the body, the body reacts by breaking it down in order to eliminate it. So… if you have injected something like heroin, the body will break it down into the morphine originally used to produce it. Hunting for heroin is futile but if you find morphine you have found signs of heroin. These products are called metabolites.

Where are the best places to collect

samples?1. Where the chemical enters

2. Where the chemical

concentrates

3. Along the route of elimination

What are the clues?• Ingested toxins show up in the stomach,

intestines, or liver• Inhaled gases are concentrated in the

lungs• Toxins that are injected intramuscularly

concentrate themselves around the injection site

• Drugs that are given intravenously are directly absorbed into the blood bypassing the stomach and liver. Concentrations are found throughout the body, are low in the stomach and liver and high in the blood stream.

Best Tissues to Sample for Poisons

• Blood – most useful tool…will show chemical and its metabolites…blood levels show what was going on in the body at the time of death

• Urine – easy to obtain…high concentrations…kidneys are along the elimination route

• Stomach contents – digestion stops at the moment of death

Best Tissues to Sample for Poisons

• Liver – the toxin sponge of your body… can reflect levels of toxins that even the blood may not reveal

• Vitreous Humor – eyeball fluid…very slow to decay so will retain toxins even longer than most other organs

• Hair – chemicals take about 5 days to show up in the core of a hair shaft…natures timeline

• Insects – toxins can accumulate (bioaccumulation) in the bodies of insects that feed off of decomposed bodies.

So, how did the person ‘expire’?

Finding out is the job of the Medical Examiner but a toxicology report is required

Determining manner and cause of death

• Natural – ex: heart attack• Accidental – ex: children putting

things in their mouths…misreading labels…mixing dangerous chemicals

• Suicidal – ex: CO poisoning…overdose

• Homicidal –ex: purposeful tampering… weapons

Let’s talk alcohol….

Do not try this at home.

Sorry, no lab.

Alcohol facts• The most commonly abused drug• Blood-alcohol levels are directly

proportional to the degree of intoxication

and are expressed in grams percent (# of grams of alcohol/100 ml blood)

• Acts on the CNS favoring the brain• Blood carries alcohol all cells of your

body but mostly to the watery areas of your body.

Alcohol Absorption•Alcohol is absorbed through the

stomach and the small intestines•The rate of absorption depends

on:»Total time taken to consume»Alcoholic content»Amount consumed»Body weight»Stomach contents

2 mechanisms for elimination:

Oxidation and Excretion

Takes place in the liver Breath

Acetaldehyde Urine

Acetic acid (goes all over body)Perspiration

CO2 + H2O

Alcohol Elimination

So, what are the tests?Presumptive:

The BreathalyzerField Sobriety

NystagmusPupil dilationWalk and Turn (heel to toe)One leg standing (and counting)Finger to nose thing

Each while listening to instructions…..

Cool graphic…. I had to use it.

What is the legal blood alcohol limit?

Currently in Michigan .10 is legally drunk, and .08 or .09 is impaired.

Alcohol and The Law

You may think that giving into a breathalyzer test violates your Fifth Amendment but you are not testifying against yourself. Giving physical evidence such as blood samples, physical measurements, photographs and fingerprints are not viewed as self-incriminating.

Silly Michigan Laws regarding alcohol

• It's illegal in Michigan for a person under the age of 21 to give a gift of alcohol beverage to anyone, even to a person of legal age.

• The Bureau of Alcohol, Tobacco and Firearms (BAFT) bans the word "refreshing" to describe any alcohol beverage

• Permitting diners to take home an unfinished bottle of alcohol beverage, rather than consuming it all before leaving to prevent "waste," encourages moderation and discourages intoxication. However, this is prohibited in Michigan.

You think Michigan is bad….

Ohio state law prohibits getting a fish drunk.

And what about Saskatchewan?

In Saskatchewan, Canada, it's illegal to drink alcohol while watching exotic dancers.

(No graphic inserted)

So, what are some other common poisons?

Cyanide – one of the most lethal chemicals known…used for executions…causes a bright cherry red blood

Strychnine – rat poisons…causes so much pain that it is rarely used in suicide

Ethylene glycol – antifreeze…a favorite (deadly) beverage among alcoholics when they can’t get ethanol

Common poisons continued

• Heavy metals – No, not Metallica, Megadeath or Anthrax but they are interesting names….arsenic, mercury and lead

• Insulin – lifesaving for diabetics but deadly overdoses

• Corrosive chemicals – strong alkalis (lye…NaOH) or acids (HCl, H2SO4)…burn the mouth, esophagus, and stomach

Presumptive Tests for poisons and intoxicants….

Marquis test – opium and derivatives

Duquenois-Levine test – Marijuana (THC)

Van Urk test - LSD

Scott test - Cocaine

Dillie-Koppanyi test – Barbituates

*** These are all color changing tests for

detection.

The Confirmatory Tests…

• Gas chromatography is by far the most widely used confirmatory test for toxins and poisons.

• Mass spectrometry is next.