Introduction
Toxicology is a branch of science that studies the harmful effects of chemicals, situations, or substances on living organisms and the environment. Toxicology explains how chemicals impact living organisms and the environment using scientific data. Forensic toxicology confirms and identifies the presence of toxic substances in tissues, body fluids (urine and blood), and organs. It helps to determine the role and contribution of toxic agents in causing death. Forensic toxicology provides a suitable conclusion during criminal investigations and drug-related poisoning cases.
What Is Forensic Toxicology?
Forensic toxicology rules out the possible cause related to poisoning, medical or legal investigation of death, and drug use. Forensic toxicology uses the principles of toxicology, clinical chemistry, pharmacology, and analytical chemistry to formulate conclusions. It helps not only in legal proceedings but also in obtaining a scientific interpretation of the findings. A forensic toxicologist will conduct these examinations, scientific tests, and studies. The forensic toxicologist collects evidence from the crime scene, like physical samples, pill packets or bottles, powders, chemicals, and trace residues for conducting an investigation.
When Is Forensic Toxicology Analysis Needed?
Forensic toxicology can be applied to investigate and formulate scientific evidence for several situations.
It includes:
-
When a person is suspected of driving after using drugs or alcohol.
-
Drug overdose and intoxication cases.
-
Use of drugs for enhancing performance by sports persons.
-
Drug-induced sexual assault, crimes, and rape.
-
Drug screening for professionals in the workplace.
-
When death is caused by drugs and poisons.
What Are the Branches of Forensic Toxicology?
1. Postmortem Toxicology
Toxicological analysis is done in death investigations to determine the cause of death. The presence of foreign agents and their contribution to death is determined. Effects of alcohol, poisons, and drugs are analyzed using the biological samples taken from an autopsy. Blood, oral fluids, tissues, hair, gastric contents, liver fluids, urine, and more can be used for analysis. Additional data relevant to the situation, like medical history, evidence from the crime scene, and autopsy findings, can also be used to formulate an analysis and interpretation. Forensic toxicologists, government officers, judicial officials, medical examiners, pathologists, and forensic toxicologists will work as a team to determine the manner and cause of death.
2. Forensic Drug Testing (FDT)
Forensic drug testing can be used to find the presence of a drug and its concentration. It is used to rule out drug usage in the workplace, drug-related probation, drug addiction and the use of drugs for enhancement of performance (sports doping). It involves two main steps, screening and confirmation. Spot test kits (marquis test and immunoassays) can be used to confirm the presence of the drug. After screening, samples can be collected for confirmatory tests. Commonly followed confirmatory tests are:
-
Gas chromatography.
-
Mass spectrometry.
-
High-performance liquid chromatography (HPLC).
-
Microcrystalline test.
-
Thin-layer chromatography test (TLC).
3. Human Performance Toxicology
Human performance toxicology will identify the effect of the drug on human activities. Drugs can alter performance, learning abilities, behavior, and skills. This branch of forensic toxicology is used for the investigation of cases involving alcohol and drug-involved driving.
What Are the Biological Samples Used for Forensic Toxicology?
-
Hair - Hair follicles store chemicals in the bloodstream and can be used as a reference for estimating the presence of drugs and harmful chemicals. Chronic alcohol abuse can be investigated using ethyl glucuronide to detect ethanol metabolites. Enzyme-linked immunosorbent assay (ELISA) can be used to analyze hair samples.
-
Blood - It can be used as an important and primary sample for toxicological analysis after the death of a person. It can also be used to estimate the level of alcohol in cases if a person is suspected of drunk driving. Blood sample testing provides an idea about the role of toxic chemicals and drugs in causing death.
-
Saliva or Oral Fluids - Oral fluids or human saliva is an alternative biological matrix to blood for the determination of xenobiotics, drugs of abuse, and other metabolites detection in both living and deceased individuals. The principle behind salivary substance detection is that the concentration of the substance found would be proportional to the fraction of the drug present in blood plasma. Saliva would hence be an important tool in forensic toxicology.
-
Urine - Urine samples can estimate the presence of drug metabolites and drugs. The presence of metabolites will depend on their chemical structure. Different chemicals stay for different amounts of time (alcohol: 7 to 12 hours, cocaine: 2 to 4 days, and morphine: 48 to 72 hours).
-
Nails - Nail examinations and laboratory tests can identify chronic exposure to drugs. Keratinized cells present in the nails can accumulate drugs in chronic users.
-
DNA - When dead bodies are found in unfavorable conditions or in cases where physical examination is not possible, DNA samples can be used. DNA typing, polymerization chain reaction (PCR), and DNA profiling are the commonly used methods.
-
Vitreous Humor - It is a gel-like substance present in the eye. It will be stable after death for months and can be used to determine the presence of various drugs (cocaine).
-
Gastric Contents - Toxicological analysis of gastric contents can be used to determine the presence of drugs, poisons, pills, and other signs.
-
A Post-mortem Sample - Examination of the spleen, liver, gastrointestinal tract contents, vitreous of the eye, and brain will provide valuable information about the cause of death.
How Are Toxins Detected in Forensic Toxicology?
Analytical methods are used to identify and confirm the presence of toxins and drugs in the human body. It includes both quantitative and qualitative tests. Gas-liquid chromatography is the most important test used to separate different compounds from one another in the same sample. Initial screening tests are used to identify the presence of certain chemical compounds before applying analytical tests. Analytical tests are selected based on the requirements and properties of the evidence collected.
Conclusion
Forensic toxicology analyzes biological samples like urine, blood, saliva, hair, and others to identify and confirm the presence of toxins and drugs. Analytical tests done in forensic toxicology gives an idea about the chemical substances present and also the concentration. This evidence can be used in formulating conclusions in medico-legal cases.
