Toxicology and criminal justice

Definition: Science concerned with the effects of harmful and toxic substances on living organisms

Significance: Toxicology plays a prominent role in many investigations of homicides, accidental deaths, and suicides.

In its most elementary form, toxicology is the study of poisons. However, scientific advances and research have complicated definitions of toxicology. Some scientists regard toxicology as the study of chemistry and chemical composition, while others regard it as the study of biological poisoning. Here, toxicology is defined as the study of the chemical composition, symptoms, identification, and treatment of foreign substances (to include poison, alcohol, industrial chemicals, poisonous gas, and illegal drugs) on living organisms.

The study of toxicology encompasses many scientific disciplines, including chemistry, biochemistry, epidemiology, pathology, physiology, and pharmacology—all of which are concerned with substances that can be ingested or inhaled or that can make direct contact with skin and eyes. The adverse effects of these toxins—which are commonly known as poisons—may include illness, injury, and death, depending on the types and amounts of the toxins that enter the body.

History of Toxicology

The scientific field of toxicology is comparatively modern, but study and use of toxic substances has a long and well-documented history in human societies. In fact, knowledge of dangerous toxins can be traced back to prehistoric humans, who used their senses of touch and taste to recognize poisonous plants and animals. Early humans extracted the poisons they found for use in medicinal healing and the manufacture of poison-tipped weapons for hunting and warfare.

Scientific toxicology began to take shape during the Renaissance. During the early sixteenth century, the Swiss scientist Paracelsus, who is regarded as the founder of biochemistry, instituted what is now called the dose-response relationship, a significant tenet in toxicology. He posited that everything had the potential to imitate a poison and it was the dosage that dictated the body’s response. Small doses yielded harmless effects, while larger doses resulted in higher degrees of toxicity.

The first important work on toxicology was published in 1813 by the Spanish physician and chemist Mathieu Orifila, who is now regarded as the founder of the field of toxicology. He was the first person to established connections between the chemical and biological properties of poisons.

Forensic Toxicology

Forensic toxicology was developed to solve the “invisible” crime of poisoning. Poisoning has been a popular method of committing murder for millennia. In the ancient world, the many illustrious figures who were victims of poisoning included the Greek philosopher Socrates, Egypt’s Queen Cleopatra, and several Roman emperors. Not only were carefully selected and administered poisons impossible to identify, but the very fact that they had been administered might also go undetected.

The first murder trial to showcase toxicological testimony occurred in England in 1751, when the medical testimony of four doctors resulted in a woman being found guilty of murdering her father with arsenic. The verdict in that case was later criticized because the doctors had used sensory data rather than scientific measures to identify the presence of arsenic in the murdered man’s food. The first scientific use of toxicology in the courtroom occurred in 1840, when traces of arsenic were found in the body of a man, whose wife was subsequently found guilty of poisoning him.

Throughout history, detection of poisoning crimes and identification of the poisons used have posed difficult challenges to investigators. The effects of most poisonous substances can be misdiagnosed as symptoms of common medical diseases, thereby rendering the toxins virtually untraceable. In modern crime investigation, toxicological sections have become commonplace parts of crime labs. Their task is to identify foreign substances in bodies and communicate their findings to law-enforcement investigators.

Toxicological Analyses

A standard toxicological procedure includes preliminary examinations of blood and urine samples and sometimes strands of hair. In some cases, full autopsies are needed so that tissue samples can be removed from various organs. Tests of the samples can detect the presence of chemicals and other foreign substances that have been ingested into the body.

In early times, the poison of choice for murder was arsenic, as it was readily available as a rat poison. Its effects on humans vary with the amounts ingested. Large doses are fast-acting and cause damage to the brain, liver, and spinal cord. Conversely, small doses ingested over extended periods of time show subtle effects such as nerve damage, headaches, nausea, numbness, and muscle weakness. Both methods of ingestion ultimately kill, but smaller doses are less detectable.

Bibliography

Klassen, C. D., and J. B. Watkins. Casarett and Doull’s Essentials of Toxicology. New York: McGraw-Hill, 2003. Detailed explanations of the basic concepts and principles associated with toxicology.

Levine, B. Principles of Forensic Toxicology. Washington, D.C.: AACC Press, 2003. Book designed for use in one-semester undergraduate courses that explores the principles and theories associated with forensic toxicology.

Olson, K. R. Poisoning and Drug Overdose. New York: McGraw-Hill, 2003. Accessible reference guide to aid clinicians in the diagnosis and treatment of toxic poisoning and drug overdose.

Rudin, N., and K. Inman. An Introduction to Forensic DNA Analysis. 2d ed. New York: CRC Press, 2001. Comprehensive reference guide to DNA for lay readers.

Timbrell, J. A. Introduction to Toxicology. New York: CRC Press, 2001. User-friendly introductory text for students that serves as an outline to the basic tenets and origins of toxicology.

Trestrail, J. H. Criminal Poisoning: An Investigational Guide for Law Enforcement, Toxicologists, Forensic Scientists, and Attorneys. Totowa, N.J.: Humana Press, 2000. Comprehensive guide to the identification of toxic poisons used in homicides.

Williams, P., R. James, and S. Roberts, eds. The Principles of Toxicology: Environmental and Industrial Applications. New York: John Wiley & Sons, 2002. Guide for health professionals in the fundamentals of toxicology in both occupational and environmental settings.