Responsibilities of Forensic Toxicologist

Responsibilities of Forensic Toxicologist

Toxicology is the scientific discipline that deals with the study of poisons and their effects on various living beings. While Forensic toxicology deals with the legal and medical aspects of poisons and their harmful effects on the human body.

Earlier toxicology was studied as a separate field dedicated to poisons. With more research and explorations the effects of poisons on the human body also gained attention as an important discipline, which leads to the merging of toxicology with Medical Jurisprudence.

The subject of Toxicology then as a branch of Medical Jurisprudence is to embody all this information into one science. It ranges over the whole vast field of medical learning and knowledge drawn together from a variety of quarters’ facts and principles which are seldom at any other time viewed in combination. 

Now, the person who studies toxicology along with its medicolegal aspects is known as a Forensic Toxicologist. Forensic toxicologists are treated as experts in the court where they represent their opinion based on the analytical results.

Here in this article, we have discussed the various roles of a forensic toxicologist. Briefly, the role of a forensic toxicologist can be listed as follows:

  • The analysis includes detection, identification, and frequently the quantitation of drugs and chemicals in biological samples, which generally are obtained from human subjects;
  • Interpretation of the analytical results that provide opinions as to the meaning of the presence of the detected substances, e.g., the effects that these drugs and chemicals may have produced on the subject.
  • Reporting the presentation of the analytical results and often the interpretation derived from them, either in written form, such as laboratory reports and written reports or as sworn testimony at deposition or trial.

These roles are common to all the areas of forensic toxicology- postmortem forensic toxicology, human-performance forensic toxicology, and forensic urine drug testing.

Role of Forensic Toxicologist

The diverse responsibilities of a forensic toxicologist have been discussed below in detail.

1. Analysis of Drugs

Forensic toxicologists may be involved as experts in a variety of widely disparate events such as automobile accidents, undocumented deaths, therapeutic misadventures, pre-employment physicals, and alleged parole violations. No matter how dissimilar the events may be, the initial role of forensic toxicologists in each case is to determine whether any exogenous drugs or chemicals are present in samples obtained from individuals involved in the event.

The word “analysis” in this context should be considered to refer not only to the analytical methods that will be used to detect these substances but also to the several procedures that occur between the event of interest and the completion of the last analysis to which the sample is subjected.

The methods of analysis that are employed to detect, identify, and quantitate drugs or chemicals present in biological samples will depend upon both the analytical strategy employed by the laboratory as well as any specific evidence that may indicate which drugs or chemical subjects may have been exposed.

Months or even years after the initial analysis, a reanalysis of one or more samples may be required as a result of several circumstances, e.g., the issuance of a court order allowing the defendant’s expert to analyze the samples, the discovery of additional case information suggesting that drugs which were not considered initially, may have been used by the subject, and the development and availability of improved methods allowing more sophisticated and informative analyses to be conducted.

2. Sample Selection

Generally, postmortem toxicologists can select samples required for the initial analysis and any reanalysis from among any in the body, except when the desired samples have been destroyed, e.g., as a result of incineration or putrefaction. Obviously, in the other areas of forensic toxicology, since the subjects usually are living, the samples that are available for analysis are limited usually to blood, urine, saliva, and hair.

Except for sample preservation, forensic toxicologists ordinarily are not directly involved in sample handling. However, they should be involved in establishing procedures for each of the steps of the process so that samples necessary for the analysis and interpretation of results are selected, collected, and transmitted in appropriate manners.

3. Storage Periods

Forensic toxicologists conduct analyses on samples that may have been stored for any or all of three different periods of time, identified in this text as storage periods I, II, and III.

  • Stage I– During this storage period, drugs and chemicals may undergo metabolism, synthesis, no metabolic degradation, or redistribution from one anatomical site to another. Often, as a result of these events, the alterations of analyte concentrations that can occur are of sufficient magnitude to cause errors in interpretations.
  • Stage II– This storage period, is the time between the collection and the initial analysis of the samples, usually in hours, days, or weeks in duration. During this period, the concentrations of drugs and chemicals in samples may be altered as a result of continuing metabolism, synthesis, no enzymatic degradation, or redistribution within the sample.
  • Stage III– In this storage period, long-term storage of samples is necessitated in anticipation of a future need either to repeat certain of the analyses because the results of the original analysis have been challenged or to conduct additional analyses because the continuing investigation has suggested the involvement of drugs or chemicals not considered at the time of the original analysis.

4. Analytical Strategies

The analysis of samples in forensic science laboratories is a systematic process. The first is a presumptive or screening test designed to identify samples that do not require further analysis since the analytes of interest are not detected.

Generally, the methods employed for presumptive analyses have very low detection limits, are easy to perform, inexpensive, and compatible with rapid, batch analysis.

The second component of the analytical strategy is a confirmatory method that is used for the analysis of those samples in which one or more analytes have been presumptively identified. Confirmatory tests are more specific than the presumptive test and, ideally, have detection limits that are equal to or less than those of the presumptive tests.


A forensic toxicologist is one who is capable of dealing with the analytical and medicolegal aspects of poisons. In fact, she/he is eligible to be presented in court as an expert to give her/his opinion based on the analytical results.

Being a forensic toxicologist is not an easy task as it demands a lot of efficiencies to handle the workload of analyzing multiple samples and interpreting the results at the same time.

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