Paracelsus A Grandfather of Forensic Toxicology

Paracelsus (1493-1541) was a colorful eccentric, alchemist, philosopher, and writer with unconventional ideas and enormous experimental skills. He was born into a Swiss family and named Philipus Aureolus Theophrastus Bombastus von Hohenheim. The name Bombastus was appropriate, yet he assumed the name Paracelsus, which means "greater than Celsus," a physician in Rome during the first century c.E. From his early teens Paracelsus moved frequently between universities, gathering knowledge and moving on.

Over the years Paracelsus learned and practiced medicine, gaining respect despite his personality. Most of his ideas about healing and chemistry were wrong, but he managed to upset the rusted foundations of medicine and chemistry, which was still being taught based on Roman texts. The modern equivalent would be going to medical school and learning from a book published in 1000,

Portrait of Paracelsus in the Louvre Museum, Paris (A blestock/Jupiterimages)

forming al-chemy, or "the chemistry." Although analysis and transformation of gold and other materials was part of alchemy, from its inception there were strong religious, spiritual, and mystical branches and aspects to it. It was only in the 16th and 17th centuries that the practical superseded the mystical, corresponding with the eventual rise of chemistry as a science.

Alchemists were technologists who learned by experience and passed on what they learned to a select few. It was not of particular interest to them why techniques worked. As long as they did, that was good enough. As a result, innovation came slowly. From the forensic perspective the key contribution of the ancient alchemists was in their interest

before various plagues swept Europe. Science needed a good shaking up, and Paracelsus was the man to do it.

Paracelsus's work in medicinal chemistry led him to state, "What is there that is not poison? All things are poison and nothing [is] without poison. Solely the dose determines the thing that is not a poison." Without a fundamental chemical understanding of medicines, there was no way to know what the appropriate dose was. Above a threshold any therapeutic agent can become toxic and a poison. For its time this was a revolutionary idea and one that started a chain of events that led to effective tests for arsenic in the body. Paracelsus was one of the pioneers of experimental science when science was more philosophical than experimental.

Paracelsus cannot lay claim to being the father of forensic toxicology, but it is fair to call him one of its grandfathers. He created the groundwork for the broader field of toxicology both experimentally and philosophically. He wrote widely, and his works were popular and thus widely disseminated and studied. This is one of the first appearances of modern science. Existing understanding, even if faulty, formed the basis for the next round, leading (ideally) to a continually self-correcting and improving knowledge of the world.

in fire applied to metallurgy and the use of heat as a means of separating materials from one another. Centuries later, pyrochemistry was to play a role in the first viable tests for arsenic.

The ancient era of alchemy ended as the Roman Empire faded and Christianity rose. The church was hostile to science—what it perceived as paganism—and particularly to alchemy and its magical connotations. Several centuries passed before interest in science reawakened. Of most interest here are developments that coincided with the beginnings of the Renaissance. In the Western world a key figure during this period was a man named Paracelsus (1493-1541). He played an important role in the evolution of medicine to include more chemically derived medicines to supplement the plant-based ones that had predominated treatments from ancient times. His beliefs also were rooted in alchemy, particularly those practices related to the purification of metals. This interest set the stage for chemical separations, primitive analytical chemistry, the linkage of medicine to chemistry, and the emergence of chemistry as a recognized natural science. Some authors today credit Paracelsus with being the inspiration for forensic toxicology. During his lifetime it became clear that the tools of forensic toxicology were needed.

From Roman times well into the Victorian era poisoning was a recognized profession and a logical choice for committing and concealing murder. Up until the mid-1900s infectious disease was a common cause of death. The outward symptoms of a clever poisoning looked similar to those of a death caused by infections, typhus, dysentery, and other diseases rampant in those times. Investigators had to rely on observation of symptoms and circumstances rather than on scientific evidence. This state of affairs allowed many murderers to go unpunished and also sent many innocent people to prison or the gallows. Because it was rampant and because it was considered an easy crime to get away with, poisoning drove the development of forensic chemistry more than any other crime. Among poisons, one was the undisputed favorite. Work with this metal, starting in the 1400s, led to the birth of modern forensic toxicology.


Arsenic poisoning commences the story of early forensic science. Arsenic (As) in its elemental form is a metal with an atomic number of 33 (33 protons in the nucleus) and an atomic weight of 74.9 atomic mass units.

Atomic Number 33 Atomic Weight 74.9216

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The symbols used for arsenic in alchemy and the modern periodic table of the elements. Arsenic is central to the history of forensic chemistry.

Because arsenic has two different oxidation states (arsenic III and arsenic V), it can exist in many solid and gaseous forms as well as dissolved in water. All of these different forms, sometimes referred to as species, have different toxicities, and they are usually divided into two groups: organic arsenic compounds (those containing carbon) and inorganic compounds (those without carbon). The organic forms of arsenic are generally less toxic than the inorganic forms. An example of organic form is methyl arsenic acid CH3AsO(OH)2.

The most famous form of arsenic as a poison is arsenic trioxide (As2O3), referred to as white arsenic or simply as arsenic. Dissolved in water, arsenic usually is found as an acid in the form of H3AsO3 (As III) and H3AsO4 (As V). Arsenic is found naturally in the body, but in very low amounts. People have always been exposed to arsenic in drinking water, but the degree of the exposure depends on the water's origin. Drinking water that comes from places where the soil has a high arsenic concentration, such as areas of Bangladesh, China, and the western United States, has higher concentrations of arsenic.

Arsenic has been an ingredient in medicines and cosmetics for at least 2,500 years. Preparations included treatments for skin disorders and syphilis, and as early as 400 b.c.e. it was used by the Greek physician Hippocrates to treat ulcers. Appearing in the late 1700s, a preparation known as Fowler's solution was used to treat skin problems, and later uses of arsenic focused on antimicrobial applications. This is no surprise; poisons are designed to kill, be it microbes, bugs, rats, or people. The use of arsenic as medicine was carried a bit too far in the late 1800s and early 1900s, when some people took arsenic in dilute preparations as a general health tonic. There were also legitimate uses of arsenic. Salvarsan, which contained arsenic, was the first effective treatment for syphilis, a sexually transmitted disease caused by bacteria.

It is not known when the poisonous nature of arsenic was discovered, but records of its use as a poison can be found as early as the fourth century b.c.e., during the Roman era. It was also during this period, in 82 b.c.e, that the first known law against poisoning was passed. From that period until the 1800s arsenic poisoning was widespread and difficult to detect or control. Some of the more famous poisoners include an Italian woman named Toffana, believed responsible for hundreds of deaths, and the Borgias, a prominent Italian family of the 15th and 16th centuries.

Arsenic was derived at that time from minerals and was widely available, but the identification and isolation of the element arsenic is credited to Albertus Magnus (ca. 1208-80), a German scholar, alchemist, and theologian. While there was still no clear understanding of the differences between compounds and elements, the isolation of metallic arsenic proved that the minerals that the Greeks thought were arsenic were in fact combinations of materials. In forensic terms Magnus was the first to use heat to drive off arsenic metal from the chemical matrix of a mineral. Five hundred years later the first forensic tests for arsenic would be based on this same principle.

Magnus noted that if sufficient heat is applied to minerals containing arsenic, the arsenic metal sublimes, which means that it evaporates directly to gas without going through a liquid phase. Magnus trapped this vapor and allowed the metal to condense. The same trick had been used for gold, but Magnus was the first to realize that there was such a thing as metallic arsenic and that a fire assay could be used to isolate it just as fire could be used to isolate and purify gold. For the time this was a significant insight. Gold exists as metallic gold in nature: It usually does not look like gold locked up in ores or rocks.

Magnus, also known as Albert the Great, is notable for other contributions. He became a professor at the University of Paris and counted among his students Thomas Aquinas. He also rose to the rank of bishop in a time when early science and religion were uneasy bedfellows at best. He is quoted with saying, "The aim of natural science is not simply to accept the statements of others, but to investigate the causes that are at work in nature," a sentiment remarkable for its time. As an alchemist, Aquinas was adept at using nitric acid as a means of separating gold from silver. A similar technique would be central in separating arsenic from forensic samples a few centuries later.

Once arsenic could be chemically separated from other materials, the stage was set for dramatic breakthroughs that would gradually spell the end of murder by arsenic poisoning. In 1752 science was applied to an arsenic poisoning case in England, in which a young woman named Mary Blandy was suspected of poisoning her father.

Mary Blandy (ca. 1719-52) was a woman with a problem: Her father disapproved of the man she wanted to marry. To remove the obstacle she allegedly poisoned her father in 1751 with the help of her fiancé, who provided the arsenic powder. Apparently, Mary's first attempt to add the poison to her father's tea failed. The powder formed a film on the surface of the hot liquid, and he refused to drink it. Next, her father and two household employees fell ill after consuming gruel prepared in the house. Because three people showed symptoms of arsenic poisoning, the incident was suspicious and led to an investigation.

The pot used to cook the gruel was the key piece of physical evidence. A government investigator used several tests to determine simple physical and chemical characteristics of a white residue left in the pan to determine that it was arsenic. One test involved heating the powder and noting a strong odor like garlic, characteristic of arsenic, but not conclusive proof of its presence. This and other simple tests led the investigator to conclude that the powder was arsenic. Mary Blandy was arrested, tried, and convicted for the murder of her father. She was executed by hanging in April 1 752. Among her last words was a request to the hangman not to hang her too high, for modesty's sake. Although the scientific tests used in this case were primitive by modern standards, they were among the first recorded use of scientific tests to detect and identify a poisonous material.

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  • eino
    Who is the grandfather of toxicology?
    2 years ago

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