When is forensic toxicology used

The degree of decomposition can also interfere with testing as these specimens can be difficult to analyse. Urine is the most common sample used for drug testing in the workplace, but it is not always available for post-mortem testing. Its usefulness lies in the fact that the presence of a substance in the urine is a sign that the substance had been in the blood at an earlier time usually within a few days and had been somewhat processed detecting these metabolites gives proof that the drug had been ingested.

When urine is available, tests are also conducted for presence of drugs of abuse. Depending on the case and the results of initial testing other tissues may need to be analyzed, possibly including stomach contents, liver, etc. The liver is a primary solid tissue for use in post-mortem toxicology because it is where the body metabolizes most drugs and toxicants.

Many drugs become concentrated in the liver and can be found even when there are no levels in the blood. In this latter situation, interpretation of findings is complex. Vitreous Humour - is the clear, gel-like substance that fills the eye. It can be a useful fluid to screen for a range of drugs. Vitreous humour is commonly analyzed for blood alcohol concentrations.

This is of particular interest in motor vehicle trauma, workplace accidents, suicides and homicides. Interpretation of other toxicological findings in vitreous humour is somewhat more complex.

Stomach Contents - Because drugs and poisons can often be ingested, stomach contents can provide important investigative clues. In a case of potential overdose or acute poisoning, high concentrations of drugs or toxins may be detected, depending on how much time elapsed between ingestion and death.

In many cases of acute poisoning, undissolved capsules or tablets may be discovered, allowing relatively simple drug or poison identification. The total amount of a drug or poison present in the stomach is more important than its concentration because it has not been processed by the body yet. Bone and Bone Marrow - Bone, in particular bone marrow, can be used for testing when necessary, but the availability and condition of bones in skeletal remains may limit their usefulness.

There are no data to suggest that bones from one part of the body are better than others for toxicology tests. However, it is always easier to extract samples from larger bones. Interpretation of these findings is often difficult when assisting in a death investigation, because the time that these toxins were deposited in the bones cannot be determined with reasonable certainty.

Hair and Nails - Hair specimens, usually taken from the back of the head, can be used to test for exposure to heavy metals and drugs over a period of weeks to months.

Hair is predominantly used to test for drugs such as amphetamines, cocaine, marijuana THC and heroin, and more recently tests have been created to determine if the deceased was drinking heavily in the last few months before death.

Drug analysis can also be done on finger- and toenails in order to provide an even longer potential window of exposure than hair. However, relatively little is known about how the nails process toxins, so interpretation of results is more difficult. Hair is subject to external contamination issues that can mitigate its value, so special sample preparations in the lab may be needed for a given case. In the typical autopsy, fluids and tissue samples are collected specifically for toxicology testing.

The types of samples collected from the body, and the testing targets in these biological fluids and tissues, are determined by circumstances of the case and the condition of the body.

A forensic toxicologist may work in a laboratory which focuses primarily on cases proceeding within the criminal system e. Laboratories may also provide both services e. The Centre of Forensic Sciences. Forensic toxicology labs use state of the art chemical and biomedical instrumentation capable of detecting small amounts of toxic materials. Currently, there is not one analytical technique that will detect, identify and determine the level of all toxins within the body and therefore the toxicologist must make informed decisions on what analyses to proceed with, based on the amount of sample submitted for analysis and the suspected drugs within the body.

Forensic toxicologists may also provide support to law enforcement in maintaining their impaired driving programs for both drugs and alcohol, and will provide specialized support for the operation of alcohol breath testing instrumentation. Canadian Society of Forensic Science P. This website is protected under Canadian copyright laws.

CSFS retains all rights to its own materials herein. The vitreous humor, the gel-like substance contained within the eye, is highly stable for several months following death and has been used to provide evidence of the consumption of a variety of drugs, including cocaine.

Many drugs and toxins will at some point pass through the liver and can accumulate there, examination of the hepatobiliary system is often highly informative. This system also includes the spleen, which contains a reserve of red blood cells that are frequently used to determine carbon monoxide exposure. Gas-liquid chromatography is among the most versatile and useful of these methods, as it serves to separate multiple compounds from one another in a sample.

The retention time of each compound can be used to infer the structure of the compound. Coupling gas-liquid chromatography with mass spectrometry and nuclear magnetic resonance NMR spectroscopy, provides ample data to identify and quantify a particular compound, even when present in very low concentration.

A number of initial screening tests are usually performed to tentatively check for the presence of certain compounds before more thorough analytical techniques are applied. These tests are often colorimetric in nature, and they may positively or negatively indicate the need for other tests.

Additionally, the choice of analytical techniques to be applied is often influenced by other information gathered relating to the case. For example, track marks on the body of an individual imply the use of intravenous drugs. Michael graduated from Manchester Metropolitan University with a B. He is currently completing a Ph. Greenwood, Michael. What is Forensic Toxicology?. What is Forensic Toxicology? AZoLifeSciences interviews Dr. Chiara De Gregorio about searching for musical rhythms in primates and finding their answer in the Madagascan rainforest.

In this interview, we speak to Roy Smythe, CEO of SomaLogic, about their groundbreaking proteomics technology that can simultaneously measure 7, proteins. Accept Cookie Settings. Download PDF Copy. By Michael Greenwood, M.