Postmortem Toxicology

Challenges and Interpretive Considerations

Timothy P. Rohrig

• Publisher: Academic Press
• Year: 2019
• ISBN:
  9780128151648
• Topic: Médecine
• Subtopic: Toxicologie

Postmortem Toxicology addresses the various aspects of the practice of forensic postmortem toxicology from a viewpoint of elements which must be taken into consideration for proper interpretation of the toxicological result, not in a vacuum but in a more holistic and global sense.

The volume examines pre-analytical factors, storage containers/conditions, prior medical interventions and therapy, along with information from the scene investigation and anatomical findings. This reference also provides explanation of the complicating conditions for the interpretation of the toxicological results due to postmortem decomposition, embalming artifacts and the postmortem redistribution of drugs. Tolerance is also discussed as an aid to interpreting results from a habitual/chronic user of medications and/or drugs of abuse.

The book is geared towards the current practitioner; however, it is written to be used as a valuable reference for a graduate or post-graduate level courses in forensic toxicology or forensic pathology.

• Presents a holistic approach to the interpretation of toxicology results
• Covers pre-analytical factors, storage containers/conditions, prior medical interventions, therapy, and much more
• Written for the current practitioner, but an excellent resource for graduate level students training in the field of forensic toxicology

1

Introduction

Abstract

Toxicology is one of the oldest scientific disciples. History is replete with the evolution of toxicology, early challenges being the identification of poisons or foods that had been adulterated with or naturally contain a poison. The development of various analytical techniques over time improved one’s ability to detect drugs and poisons. In fact, the development of various medical examiner systems evolved out of the eventual detection of poisoners.

There are no “absolute” rules for the interpretation of postmortem toxicological results. The proper interpretation of toxicological results requires a global awareness of the challenges and pitfalls associated with the test results and the inclusion of the totality of circumstances surrounding the death.

Death investigations can be affected by a variety of unusual complexities. Confounding factors or artifacts impacting the interpretation of results may arise from conclusions drawn from or due to preanalytical factors, the specimen container and/or storage conditions, prior medical therapy or medical intervention. Postmortem changes or artifacts introduced due to organ or tissue procurement, specimens collected from an embalmed body prior to burial, or after exhumation may also lead to misinterpretation of the toxicological results.

The focus of this treatise is a discussion of the challenges and pitfalls that may impact the interpretation of postmortem toxicological findings.

Keywords

Analytical detection; arsenic; history of poisoning; King of Poisons; LaFarge; medical examiner; postmortem interpretation; postmortem artifacts; Traite des Poisons

Toxicology is one of the oldest scientific disciples. History is replete with the evolution of toxicology, early challenges being the identification of poisons or foods that had been adulterated with or naturally contain a poison.

Toxicology is derived from the ancient Greek word toxicon [τοξικ

ν] [1]. The term relates to “bow poison.” Poisons were occasionally placed on the tips of arrows to make them more lethal. The word toxicos is derived from this meaning, leading to the word intoxicated which meant making one sick by poison arrows.

Toxicology encompasses multiple scientific areas of study; analytical chemistry, biochemistry, clinical chemistry, medicinal chemistry, anatomy, biology, physiology, pharmacology, and pharmacy. The role of the toxicologist is twofold: characterize and identify substances in the body and provide an interpretation of what their presence or in some cases absence means; relating to the behavior of an individual and/or was the detected drug or poison a causative factor in the individual’s death.

Merriam-Webster dictionary defines the noun forensic, meaning “an argumentative exercise.” The English word was derived from a Latin word forensic meaning “of the market place or form, public,” which in turn comes from the Latin word forum, meaning “market place, forum” [2]. Simply put, the forensic aspect of forensic toxicology is bringing toxicological data and interpretations into a legal setting.

The knowledge of poisons predates recorded history. The written history of toxicology may be traced back as far as 2700 BC with information in the Chinese journals discussing plant and fish poisons [7]. The Ebers papyrus is an ancient papyrus scroll dating back to c.1500 BC, which contained descriptions of various poisons and proposed antidotes. Between 50 and 70 AD Pedanius Dioscorides, a Greek physician wrote De Materia Medica (Latin translation: “On Medical Material”), which classified over 600 plant, animal, and mineral poisons; from which 1000 medicines had been made from them [3]. From 250 to 400 AD, the Romans had used poisons for executions and assassinations [4]. One of the most notable assassins was Locusta, employed by Nero as his personal poisoner, dispatching several of his wives and a brother [5]. Anyone, who has taken a course in philosophy, recognizes another victim of note during this time was the philosopher Socrates who was executed with hemlock for teaching “radical ideas” to the youth of the time [6].

The Roman Empire passed the first law against poisoning in c.82 AD called lex Cornelia de sicariis et veneficis or the Cornelian Law (against) of Assassins and Poisoners [7]. Arsenic was the poison of choice by Roman assassins; it became known as the King of Poisons. Due to the frequent use of arsenic as a poisoning agent, Roman Emperors and families of nobility hired food testers to protect themselves from surreptitious poisoning. These “food testers” could have unwillingly been the first “toxicologists” used to identify poisons.

Swiss physician Paracelsus (1493–1541), born as Philippus Theophrastus Aureolus Bombastus von Hohenheim, is credited with being the father of modern toxicology [8]. He received his baccalaureate in medicine in 1510 and was awarded his doctorate in 1516 from the University of Ferrara (main university in the city of Ferrara, Northern Italy). It was around this time he took the name Paracelus; being derived from para: beside, beyond and Celsus: a noted Roman physician. He wrote (loosely translated from German): “All things are poison and nothing is without poison, only the dose permits something not to be poisonous.” Thus, a basic tenant in toxicology is “Dose makes the Poison”; substances considered toxic may be harmless in small doses and conversely an ordinarily harmless substance can be deadly if overconsumed, for example, water or salt (sodium chloride).

Spanish Physician Mathieu J.B. Orfila (1787–1853) established toxicology as a distinct scientific discipline. He wrote, in 1813, a treatise entitled “Traite des Poisons,” which in part described techniques for the identification of arsenic in biological sample. Orfila is best known for his expert witness role in the “LaFarge” arsenic poisoning case in France; where in 1840 Marie LaFarge was tried for murder of her husband using arsenic [9], thus bringing this scientific discipline into a court of law and establishing him as the father of forensic toxicology.

In addition to the Romans recognizing poisons being used as agents for murder, England [10] and other European countries had an awareness as well. In 1851, the United Kingdom passed legislation entitled “An Act to Regulate the Sale of Arsenic”; also referred to by its short title Arsenic Act of 1851 [11]. The Act defined arsenic as “Arenious acid and the Arsenites, arsenic acid and the arsenates, and all other colourless poisonous preparations of arsenic.” This Act required documentation which identified who the purchaser was, the amount sold and the purpose of use of the arsenic; similar to various pseudoephedrine statutes currently in the United States to address the misuse of the drug as a precursor for methamphetamine production. The Act further required that the arsenic have a colorant added such as soot or indigo dye; unless it would cause the chemical to be ineffective for use in medicinal or agricultural products. The Act called for fines to be levied if the terms of the Act were violated. The Arsenic Act of 1851 was repealed by parliamentarian action by passing the Pharmacy and Poisons Act of 1933 [12].

The detection of poisons and the identification of poisoners has been the challenge to science, medicine, and law enforcement. A poisoned victim was generally identified by circumstantial evidence, with limited, to no scientific evidence to support the cause of death. Joseph Plenck (Josephi Iacobi Plenk) was the first to suggest that the proof of poisoning was by the identification of the poison in biological tissues; published in his work Elementa medicinae et chirurgiae forensis, published in 1786 [13].

The development of various analytical techniques; such as the Marsh test for arsenic in 1836 [14], the separation of alkaloidal drugs from biological matrixes in 1850 [15], and instrumental analysis began to evolve in the 1960s. More recently, spectrophotometric methods and chromatographic methods, such as gas and liquid chromatograph along with various hyphenated instrumental platforms, for example, gas chromatography–mass spectrometry and liquid chromatography–tandem mass spectrometry has led to a rapid increase in the ability to detect poisons in decedents [16].

Although detection methods of drugs and poisons were improving, the application of these in forensic work in the United States did not begin to evolve until 1804 [17]. The errors of the coroner system, as brought over from England, were being recognized, which lead to the formation of the office of the Chief Medical Examiner for the state of Massachusetts in 1877. The Chief Medical Examiner’s Office of New York saw its beginnings in 1918, with the toxicology laboratory founded under the direction of Dr. Alexander Gettler.

In fact, the development of various medical examiner systems throughout the United States, evolved out of the eventual detection of poisoners and the need for a more sophisticated investigation of death. Nannie Doss was a prolific serial killer in Tulsa, Oklahoma, USA from the late 1920’s until the mid-1950’s [18,19]. She dispatched several of her husbands, children, sisters, mother, mother-in-law, and a grandson with arsenic. Her final discovery led to legislation in the state of Oklahoma (USA) forming what is now known as the Office of the Chief Medical Examiner (personal communication: the author spent several years working for the office as the Chief and Deputy Chief Toxicologist).

Due to the ever increasing number of therapeutic agents, illicit/designer drugs that are prevalent in our society today; toxicological examinations continue to play a significant role in the evaluation of a death investigated by a Coroner or Medical Examiner system. Although the ability to detect and quantitate drugs and poisons in biological material has significantly improved over the last century; the questions remains the same: Did a drug or combination of drugs alter the decedents behavior, play a direct casual role in the death or contribute to the death or in some instances was the absence of a medication, for example, an antiseizure medication, a factor in the death or circumstances leading up to the death?

There are no “absolute” rules for the interpretation of postmortem toxicological results. The proper interpretation of toxicological results requires a global awareness of the challenges and pitfalls associated with the test results and the inclusion of the totality of circumstances surrounding the death. The first and foremost consideration of postmortem toxicological results is that they cannot and should not be interpreted in a vacuum; nor can one just pick up The Red Book or a table listing “toxic or lethal” drug concentrations to form a conclusion on what role a drug played in the death. The determination of how the toxicological results will impact the ultimate opinion of the cause and/or manner of death must incorporate not only the laboratory findings, but also include the decedent’s medical history, predeath clinical findings, scene investigation, and a thorough autopsy examination. The challenge is that in some medical examiner/coroner cases some or all of this information may be incomplete or not available at all.

Death investigations can be affected by a variety of unusual complexities. These confounding factors or artifacts impacting the interpretation of results may arise from preanalytical factors, the specimen container, and/or storage conditions, prior medical therapy may mislead the investigation as well as medical intervention prior to the death. Artifacts leading to misinterpretation may also be introduced due to or...