While the technology available to the forensic toxicologist is far superior to that of 170 years ago, the analytical challenges remain the same. And while the understanding of pharmaco/toxicokinetics and dynamics has advanced, the questions remain the same.
It could be the year 1850, or 1950, or 2008…take your pick. It was a few days since the family dinner that the husband took ill. The nausea, vomiting, and diarrhea had been relentless. And that garlic taste in his mouth, it just wouldn’t go away. And finally, almost as a relief, he died. Whether as a relatively new bio-analytical science in 1850, or a discipline with remarkable, state-of-the-art equipment today, forensic toxicology has been asked to address concerns with such cases, to speak for the victimized husband, to tell the story of what caused his illness and death, and to provide the “smoking gun,” the identification of the arsenic that led to the wife’s conviction. Truth be told, however, things are neverso clear. What follows is an accounting of the past, present, and “future” states of forensic toxicology, a discipline key to a wide variety of case types ranging from pre-employment testing to death investigation.
THE DUALITY OF FORENSIC TOXICOLOGY
Forensic toxicology is a scientific discipline with a split personality. While toxicology can be defined as the study of the adverse effects of chemicals on living things, the forensic component also mandates an analytical component. In this latter regard, the forensic toxicologist is also an analyst, or more to the point, an analytical chemist. It is the ability to bridge the two fields that defines the proficiency of any forensic toxicologist. The application of the two fields to cases ranging from: human performance issues, e.g., driving under the influence of alcohol and drugs; workplace testing and athletics; clinical toxicology, e.g., helping to diagnose the poisoned patient; and, postmortem issues, e.g., helping to determine a cause of death, all make this field dynamic and fascinating. However, understanding the modern development of this duality sheds light on the impact of forensic toxicology on our criminal and civil justice systems and society.
The origin of modern analytical toxicology, and for that matter forensic toxicology, is often attributed to a Spanish physician named M.J.B. Orfila who actually practiced his vocation in France during the early to mid-1800s. Despite the establishment of laws against poisoning dating back to 81 B.C.E., it was his analysis of autopsy materials to identify poisons, and the subsequent accounting of such, that represented the first systematic approach to the identification of poisons. It was this approach that led to the first courtroom toxicological testimony by Orfila in 1840 during the trial of Marie Lafarge in France for poisoning her husband to death with arsenic.1-3
If one focuses solely on arsenic, the evolution of bio-analytical forensic toxicology is easily made clear. Even prior to Orfila, a number of chemists worked on the identification of this widely used poison during that time period. Most of the developed tests surrounded the precipitation of arsenic through oxidative and reductive processes. Unfortunately, none of these tests proved sensitive enough for forensic toxicological purposes. However, in 1836, James Marsh, a British chemist, published an improved, sensitive method for the detection of arsenic. This method allowed for the physical presentation of the arsenic finding in a courtroom, and in fact, was the test used by Orfila in the Lafarge case.4 In 1842, Hugo Reinsch developed the namesake test that “plates” arsenic onto copper wire, turning it black. This was followed by Max Gutzheit’s semiquantitative test in 1879, again ultimately involving precipitation of arsenic. This latter test remained a hallmark in arsenic testing for almost 100 years.5 In the mid-1950s, Alan Walsh developed atomic absorption spectrometry. Within a decade or so after that, this instrumental technique was being readily used for a variety of elemental analyses, including arsenic. In the mid-1980s, ICP-MS (inductively coupled plasma-mass spectrometry) was made routinely available, a method recognized as the current standard in arsenic testing.