Module 1 - Forensic Toxicology

Lesson 2 - The Effects of Poisons and Toxins

Examples of Poisons

Hundreds of poisons exist. Symptoms caused by some well-known poisons such as carbon monoxide, arsenic, cyanide, and strychnine are described below. Note that these are only a few of the existing poisons. Criminal investigations involving poisoning do not necessarily involve only these types of poisons.

Carbon monoxide is one of the most common poisons in accidental or suicidal poisoning cases. Carbon monoxide (CO) is produced from the incomplete combustion (burning) of carbon based fuels and may be released into living spaces by defective gas appliances (such as ovens, furnaces, and heaters). When CO is inhaled, it prevents oxygen from attaching to the hemoglobin molecules within red blood cells. When excessive amounts of CO are absorbed, an individual suffocates to death because oxygen cannot reach the cells of the body. An obvious symptom of CO poisoning is the bright red appearance of the skin and internal organs.

Carbon monoxide poisoning by hooking up a hose to the exhaust pipe of a car or running a car inside a closed garage used to be a common method of suicide. The amount of carbon monoxide produced in car exhaust is dependant on a number of factors but, since the development of catalytic converters, the percentage of carbon monoxide in car exhaust has been greatly reduced.

In an average adult, a carbon monoxide blood saturation level greater than 50 to 60% will cause death. However, if an average adult has a blood-alcohol concentration level at 0.20%, a carbon monoxide blood saturation level as low as 35 to 40% will kill.

Richard Saferstein, Ph.D: Criminalistics—An Introduction to Forensic Science. New Jersey: Prentice-Hall, Inc., 1998. (p. 317)

Arsenic is a semi-metal (metalloid) found on the periodic table. It is used in various agricultural insecticides and as a material semiconductor in integrated electrical circuits. Arsenic ingestion causes multi-organ failure by interfering with ATP production, inhibiting enzyme and mitochondrial activity, and increasing hydrogen peroxide production. The taste of arsenic is disguised easily by food. The symptoms of arsenic poisoning include nausea, stomach cramps, and burning in the throat. If a person is given small doses of arsenic over time, the effects may be mistaken for food poisoning.

During the 1800’s, women used arsenic to improve their complexions by mixing it with vinegar and chalk and either eating it or rubbing it into the skin.

- Wikipedia: Arsenic

Cyanide (CN) is any chemical compound that contains a carbon atom triple-bonded to a nitrogen atom. The CN group is found in many kinds of compounds that may be solids, liquids, or gases. Cyanides are used in mining, electroplating, photography, and the making of blueprints. They are also used in many insecticides. Cyanide is an enzyme-inhibitor; it breaks down an important enzyme in the mitochondria of cells, thereby preventing ATP production. Without the energy from ATP, body cells die. Cyanide tends to target cells in the brain, spinal cord, and heart – and causes quick death.

The poisonous gas, hydrogen cyanide (HCN), smells like bitter almonds. Because of inheriting a recessive genetic trait, approximately 40% of the population cannot smell hydrogen cyanide.

- Wikipedia: Cyanide

Cyanide was reportedly used by Iraq in wars against Iran and against the Kurds during the 1980s. During World War II, a gaseous form of cyanide was released into the gas chambers of Nazi concentration camps in Auschwitz and Majdanek to kill countless Jewish people.

Strychnine is a colourless crystalline compound found in the seeds of a tree native to India. The most common use for strychnine is as a pesticide for rodents. Strychnine is both poisonous and very bitter. Only 1/50 of a gram can kill a person. Strychnine blocks important amino acid receptors in the brain and spinal cord causing intense muscle spasms throughout the body. When strychnine inhibits the activity in the medulla oblongata, the victim’s heart and lungs stop, resulting in death. When death occurs, rigor mortis sets in immediately regardless of the position of the victim. Typically, the victim’s eyes remain wide open.

During the 1904 Olympic Games, American Thomas Hicks collapsed after winning the marathon. Revival took several hours, but he survived. He later admitted to drinking brandy laced with strychnine believing this would help him win the gold medal.

- Wikipedia: Strychnine

The chart below identifies several additional common poisons and some of the symptoms caused by each.

Name of Poison:	Related Symptoms
acids (nitric, sulfuric)	burns around mouth, lips, eyes and digestive tract
lead	weight loss, sluggishness, vomiting
mercury	brain damage, birth defects, death
thallium	diarrhea, abdominal pain, skin rash, abnormal heart beat

- Source: Biocrawler website

The UN standard symbol for a poisonous substance is the Jolly Roger, or skull and crossbones. However, many companies consider this symbol negative for purposes of marketing. Therefore, in North America the symbol, Mr. Yuk (see below), is replacing the Jolly Roger. Companies argue that the skull and crossbones symbol may attract children because of its association with pirates, but Mr. Yuk does not.

Mr. Yuk!

- Source: The Brown Daily Herald

Glossary Term: Hemoglobin

The iron-containing respiratory pigment found in red blood cells that carries oxygen and carbon dioxide

Glossary Term: Suffocate

To cause discomfort, kill, or destroy by preventing access of air or oxygen; to impair the respiration of; asphyxiate

Glossary Term: Metalloid

A nonmetallic element, such as arsenic, that has some of the chemical properties of a metal

Glossary Term: ATP (Adenosine Triphosphate)

A high-energy phosphate molecule required to provide energy for cellular function; the energy source your muscles use for short bursts of power

Glossary Term: Enzyme

Any of numerous proteins produced by living organisms and functioning as biochemical catalysts necessary to begin internal chemical reactions

Glossary Term: Mitochondria

Small cell organelles in the form of spherical granules, short rods, or long filaments found in almost all living cells (They produce energy in the form of ATP.)

Glossary Term: Medulla Oblongata

Part of the brain, especially the base of the brain where the spinal cord connects; controls involuntary activities in the body such as heart rate, breathing rate, and digestive activitiesAny of numerous proteins produced by living organisms and functioning as biochemical catalysts necessary to begin internal chemical reactions

Glossary Term: Rigor Mortis

muscular stiffening following death (The onset may vary from about ten minutes to several hours or more after death, depending on the condition of the body at death and on factors in the atmosphere, particularly temperature. It is caused by chemical changes in the muscle tissue. The state of rigor usually lasts about twenty-four hours or until muscle decomposition occurs by acid formation.)