Forensic Toxicology
Toxicology is the investigation of poisons. Specifically, toxicology is concerned with the chemical and physical features of poisonous chemicals and their physiological effects on living beings, as well as the creation of protocols for the treatment of poisoning. \n
It is well known that drinking a lot of water over a long period of time can cause a dangerous imbalance of electrolytes. This strange habit of drinking a lot of water is called psychogenic polydipsia, and it can happen in some types of schizophrenia.
\ Recently, toxicology has grown to include a wide range of topics. For example, it now looks at the risks of using drugs, pesticides, and food additives, as well as occupational poisoning, environmental pollution, the effects of radiation, and, unfortunately, biological and chemical warfare.
\ The main job of a forensic toxicologist is to find and measure poisons in autopsy tissues and body fluids, as well as in blood, urine, or stomach contents taken from a living person.
\ Without toxicologic examinations that show the presence of the poison in the tissues or bodily fluids of the deceased, poisoning as a cause of death cannot be established beyond a reasonable doubt.
\ When poisoning is not the cause of death, the forensic toxicologist can frequently offer important information about the circumstances of a death.
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History of Forensic Toxicology
Prior to the nineteenth century, physicians, attorneys, and law enforcement agents held erroneous beliefs regarding the symptoms of poisoning.
\ In the early 18th century, Hermann Boerhoave, a Dutch physician, hypothesized that various poisons developed distinctive odors when heated and evaporated.
\ During the Middle Ages, professional poisoners advertised their services to both royalty and commoners. The most prevalent poisons were plant-based (such as hemlock, aconite, and belladonna) and toxic metals (arsenic and mercury salts).
\ Throughout the French and Italian Renaissances, Pope Alexander VI and Cesare Borgia elevated political assassination by poisoning to the status of a noble art.
\ In 1775, the brilliant Swedish chemist Karl Wilhelm Scheele found that chlorine water converted white arsenic to arsenous acid.
\ In 1821, Sevillas used arsine breakdown to detect minute levels of arsenic in the stomach contents and urine of poisoning victims.
\ In 1836, James M. Marsh, a chemist at the Royal British Arsenal in Woolwich, utilized the creation of arsine gas to establish the first accurate method for determining the presence of an absorbed poison in human tissues and fluids, such as liver, kidney, and blood. \n
In the 1800s, forensic toxicology emerged as a distinct scientific subject. In 1814, the "father of toxicology," Mathieiv J. B. Orfila (1787–1853), wrote Traité des Poisons, the first systematic examination of the chemical and physiological nature of poisons.
\ In 1850, Belgian chemist Jean Servials Stas successfully isolated an alkaloid poison by utilizing a solution of acetic acid in ethyl alcohol to extract nicotine from the tissues of the murdered Gustave Fougnie.
\ European toxicologists were at the forefront of the development and application of forensic sciences in the second half of the 19th century.
\ American Board of Forensic Toxicology was established in 1975 in order to examine and certify forensic toxicologists.
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Deaths Investigated by Toxicologists
Accidental Poisoning
Accidental poisonings can occur in the workplace as a result of negligence or incidents that expose personnel to harmful substances. While there is a high risk of unintentional poisoning in industry, today's safety standards and regulations, as well as the availability of emergency medical services, keep industry from becoming a cause of many fatal intoxications. \n
Deaths from Drug Abuse
Many poisonings are caused by drug abuse, which is the non-medical use of drugs or other compounds to alter mood or induce euphoria. Drug abuse can involve using illegal substances like heroin or phencyclidine, as well as restricted or controlled substances like cocaine, barbiturates, and amphetamine. It can also involve using chemicals in ways that aren't compatible with their intended uses, including inhaling solvents and aerosols.
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Suicidal Poisoning
When someone has been poisoned, suicide is a typical cause of death. Carbon monoxide, a gas produced by the incomplete combustion of carbonaceous substances, is the most prevalent suicide substance.
Homicidal Poisoning
Today, poisonings happen often by accident or on purpose, but murder by poison is rare. Finding out that someone was poisoned to kill themself is often the hardest part of an investigation for police and medical professionals. General proof of poisoning comes from knowing what symptoms the person who died had before they died, from the pathologist's examination of the body after death, and from the toxicologist isolating and identifying the poison.
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Toxicological Analysis
Before starting the analysis, the toxicologist has to think about a few things, such as how much of the sample is available, what kind of poison is being looked for, and how the poison might change in the body. Because he only has a small number of samples to work with, the toxicologist must come up with an analytical method that can find the most compounds. \n
Color Test
A color test is a chemical method in which the substance being tested is acted with by a reagent, causing the reagent to change and resulting in the production of an observable color or color change. Color tests can be used to find out whether a particular compound or a class of compounds is present.
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Microdiffusion Test
To quickly isolate and find volatile toxins, microdiffusion analysis is employed. A straightforward microdiffusion device is a small porcelain dish with two distinct compartments, an inner well encircled by an outer well created between the outside edge of the inner compartment's wall and the dish's higher outside wall.
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Chromatography
Chromatography is a way to separate substances. The parts of a sample mixture are spread out between two phases. One phase is fixed, while the other, the mobile phase, moves through a matrix or over the surface of a fixed phase.
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Thin-Layer Chromatography
The stationary phase in thin-layer chromatography (TLC) is an absorbent, frequently silica gel, placed on a sturdy substrate (usually a glass plate).
The toxicologist has a tentative identification of the compound if it migrates the same distance in this TLC solvent system and reacts to the applied sprays in the same way as the reference drug; however, he has ruled out all compounds that do not migrate the observed distance in this TLC solvent system and do not react in the same way as the reference drug.
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Gas Liquid Chromatography
The mobile phase in GLC is an inert carrier gas (such as helium or nitrogen) that flows over a packed column with a stationary phase coated on a solid support or through a narrow column with the stationary phase covering the walls (capillary column).
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High-Performance Liquid Chromatography
In high-performance liquid chromatography, the mobile phase is a liquid that moves continuously under pressure through a column of solid stationary phase.
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Spectroscopy
Spectroscopy is the study of the absorption and emission of light radiation. All molecules absorb radiation; however, the wavelength of the absorbed radiation can range from X-rays to ultraviolet, visible, and infra-red to microwave and radio frequencies.
\n A spectrophotometer is comprised of a radiation source, a sample cell through which the radiation passes, and a detector for measuring the absorption of the radiation.
\ Absorption of ultraviolet (UV) light can induce electronic transitions in organic compounds, promoting electrons from low-energy to high-energy orbitals.
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Mass Spectrometry
Mass spectrometry involves subjecting a sample to an intense bombardment of electrons in order to create a charged molecule or shatter the sample into ionic fragments.
\ The "mass spectrum" depicts the relative abundance of the various mass-to-charge pieces.
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Immunoassay
Antibodies used in immunoassay must strongly bind the target drug while binding poorly or not at all to any other substances.
Therefore, immunoassay methods are ideal for the rapid detection of target toxins in biological samples like urine.
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Interpretation of Findings
The toxicologist must interpret the results of the specimen analysis in terms of the physiological effects of the toxicants at the quantities identified on the deceased.
\ Assessing the physiological significance of analytical results is sometimes the most challenging task a forensic toxicologist faces.
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