Forensic toxicology is a discipline of forensic science which includes the study of toxic or harmful substances or poisons (any substance which can harm our body) and their effect. It is a special area of analytical chemistry.
Forensic toxicology involves the study of alcohol, drugs (licit and illicit) and poisons with including chemical composition, preparations and identification, postmortem signs of the poisoning etc. It also includes the absorption, distribution and elimination of such toxic substances in the body, their response on the particular part of body which gets affected.
- The toxicity of a substance depends on the dose ingested and also on the age, weight and state of health of the person who takes it.
- Toxic substances can be administered by ingestion, injection or through the skin.
- Toxic materials can be in different forms like gaseous, liquid, solid, animal, mineral, and vegetable etc.
- Usually poisons can be taken by the body in a single massive dose.
- It works in small quantities. So the sensitive analytical instruments are needed for their detection.
- Some toxins have medicinal value, antidotes and can be identified by prompt treatment and their symptoms.
- The extraction of some poisons can be done with use of organic solvents like ether or chloroform.
- Chromatography technique is used to identify poisons.
- The other mostly used technique immunoassay which is used to identify antibodies made up for the foreign bodies in the blood. It’s a developing method.
Forensic Toxicology has been developed around for hundreds of years. The first book on forensic toxicology was published in 1813 by Mathieu Orifila
. He is Spanish chemist and physician who is known as “Father of Toxicology”
published a book a Treatise of General Toxicology.
Another work was done by Albert Swaine
in 1836. The book “Elements of Medical Jurisprudence”
was written by him. This book was based on the theory of Forensic Toxicology. The English chemist James Marsh also discovered a correct way to detect arsenic in the body in 1836.
The main work of a mechanistic toxicologist is to determine the harmful effects of substance on living organisms. They judge the risk of any substance for making it available.
A forensic toxicologist perform a major role in an investigation for recording any physical symptoms or for collecting evidences at a crime scene such as bottles, powders, trace residue, and chemicals. With all these kind of information and samples, the forensic toxicologist must identify about the concentration, nature and effect of toxic substances.
Today one of the popular Forensic Toxicologists is Mr. Olaf H. Drummer who is the president of The International Association of Forensic Toxicologists (TIAFT).
Work of Forensic Toxicologists
- The various types of scientific tests on tissue samples and bodily liquids are performed by forensic toxicologist to know about the existence of any foreign drugs or chemicals in the body.
- Thus forensic toxicologists identify substances in the body which may have caused the crime.
- These identified substances can be various illegal or prescription drugs, alcohol, poison, metals, chemicals, or gasses.
- The job of forensic toxicologist includes drug-testing, environmental areas testing and the presence of “date rape” drugs.
Place of working
- Forensic toxicologists’ work for the legal and medical industries.
- Their reports are very helpful for court cases and in crime sector to solve the murder mysteries.
- They also work with poison control centers of medical field which give the information about safety of food and drugs.
Detection and Classification of Drugs
- Forensic toxicologists will use different kinds of methods for testing of substances which depends on the type of drug.
- Some of the tests are gas-liquid and thin-layer chromatography,
- immunoassay. To use these tests for legal purposes, the technician must confirm about his original results with a second test.
- The spot tests like testing blood or hair samples with a reagent solution are also used for some illegal drugs (marijuana, opiates, cocaine etc).
Forensic serology is the detection and study of various bodily fluids specially blood and show their relationship to a crime scene. The forensic serology involved the testing of the blood, bloodstain and character of blood. A forensic serologist analyzes semen, body fluids, DNA typing.
The fluid portion of blood is plasma containing water, serum (yellowish and contains white cells and platelets). The analyst can know about the freshness of a blood sample because serum clots several minutes after exposure to air. The antibodies present in serum are also very useful in forensic implications.
The forensic serology is all about antigens of red blood cells and antibodies. The fundamental principle of serology is that for every antigen, a specific antibody is present. Two antiserums are needed for blood typing:
When these antiserums are dropped in samples of blood, it makes the difference between the samples of a normal appearance and clotted samples.
For example, Blood of type A will be clotted by anti-A serum while type B will be agglutinated by anti-B serum, AB blood by both and O blood by none of these two. The lectin is the most commonly used types of antiserums. DNA can be extracted from blood and also from bone marrow, tooth pulp, and hair roots.
Blood is commonly used in DNA testing. The steps of process are given below.
The important work of the forensic serologist involves.
- First the blood samples are collected from the victim and crime scene.
- White blood cells and red blood cells are separated.
- The nuclei of white blood cells are used for extraction of DNA.
- DNA strand cut in fragment with the use of specific enzyme.
- These fragments are put into a bed of gel with electrodes.
- DNA fragments are sorted in length by electric current.
- Thus an X-ray photograph /autoradiograph is produced by radioactive treatment of imprints which socks up on an absorbent blotter.
- They perform test for examining the presence of body fluids.
- They evaluate evidences for DNA analysis.
- They also perform polymerase chain reaction (PCR) which based on typing of STR (short tandem repeat sequences) of genomic DNA, or mitochondrial sequence analysis. Then report the results of analysis in court to solve cases.
In the forensic toxicology, various kind of legal and medical case are solved. It was the murder case of Charles Francis Hall in 1871 that became ill after drinking coffee. After a long investigation, it was said that Captain Hall had died from natural reasons.
But the investigation proved that poison was the cause of his death. Scientists had tested that each dose of hair arsenic like leaves a permanent and measurable record in every growing strand which absorb by roots of human hair. If someone dies from arsenic poisoning, there should be a high concentration near the roots.
Fingernails samples will also provide information about that. They went that place and performed an autopsy (it’s a method in which tissue sample are taken from human organs) on the ground because the coffin was frozen into the earth and in the body.
The fat of Hall’s body had been changed into adipocere which is a substance like soap and had an effect on the internal organs. They collected the samples from the soil surrounding the coffin, hair samples, and finger nails and used the modern technique called neutron activation analysis. In this technique, a stream of neutrons is used to irradiate on a specimen who is placed in a nuclear reactor.
The specimen becomes destabilized and than becomes radioactive. This radioactive substance emits gamma rays of a particular wave length. These rays are measured in a spectrometer. Even a small amount of sample can be traced in this treatment. But the soil samples showed a high percentage of arsenic and this was indicating a murder case.
Scientist found from his finger nail samples that he had taken a large amount of arsenic before few days of his death. The differential growth of his nails and hair samples also proved that the arsenic had leached through the coffin into the body. Thus, by using the new technique,it was proved that Hall had been murdered. Thus, the various murder mysteries are solved with the help of forensic toxicology techniques.