Sample Essay on Forensic Toxicology


Toxicogenomics is an emerging discipline that combines expertise in toxicology, genetics, molecular biology, and environmental health to elucidate the response of living organisms to stressful environments. Forensic science utilizes the new technology to examine the behavior of the gene in different chemically treated environments.

Two significant technologies in toxicogenomics are the DNA microarray, a collection of gene-specific DNA fragments placed on the solid surface, and RNA sequencing whereby advanced sequencing technologies are applied to complementary sequence DNA in order to get information in a given RNA sample. These technological understandings measure the behaviors of thousands of genes at different periods to develop a global picture of the cellular function, for instance, response to a certain drug. Accordingly, the big picture created is regarded as gene-expressions profiles, which fall under the field of toxicology.

The assumption that similar gene-expression profiles direct similar physiological responses inspire the use of gene-expression profiling in toxicogenomics to distinguish the toxicological properties of a given chemical entity. According to Gavin (2014) “The idea motivates the use of bioinformatics clustering approaches, where chemical entities with similar gene-expression profiles are grouped together with the aim to define chemical classes.” Again, connectivity mapping that gives compounds with analogous profiles on the constituent genes may be applied.  Forensic science has tried to generate mechanistic analysis on the biology behind the response of certain compounds to the chemical agents, and the prediction evaluation, where the type of genes acting at an early phase of toxicity is explored.

Toxicology experts analyze individuals and species’ differences in the underlying DNA sequence itself can lead to different responses to the environmental genomics. “The genomics part of toxicogenomics also entails several other forms of profiling technologies including protein profiling and metabolic profiling in a cell or tissue” (Kobilinsky, 2012). Toxicogenomics potentially provides faster and inexpensive approach to finding differences between experimental animal and human responses to chemicals.

Toxicogenomic knowledge creates significant insight on forensic toxicology, which is defined as the application of toxicology in the justice matters. Gavin (2014) notes, “Forensic toxicology covers three major subcategories: postmortem forensic toxicology, human performance toxicology, and forensic drug testing.” Prior to the advent of human performance forensic understanding, for example, alcohol and drug testing in drivers and drug testing in urines, comprises of the investigative cases in toxicology. Forensic toxicologists appreciate this knowledge in conducting examinations on the dead bodies of the individuals and animals.


The primary premise of toxicology and risk assessment is that experimental animals are generally appropriate models with which to identify potential hazards to humans. Fundamentally, the exposure to poisonous substances and the effects are analyzed under the controlled conditions. Once analyzed, each toxin depicts a unique pattern on every gene, simplifying the means of distinguishing and classifying different degrees of toxicity.  However, the dependability of extrapolation for certain chemicals is frequently controversial. “Despite the dependence on animal models for predicting human health effects in the regulatory arena, there can be important differences between how non-human animals and humans respond to chemicals” (Kobilinsky, 2012).

A fundamental question that arises from the toxicogenomic is, “How good can cross-species extrapolation ever be?” this question is tackled through two broad strategies. First, it involves understanding the biologic mechanisms of action of individual compounds from two different perspectives. These are: whether identifying the dominant mechanisms in species such as mice or rats could be enough to generate information concerning human beings, and whether all the potential toxicity mechanisms in a species can be characterized developing reliable information to create a classical version for humans.

The toxicogenomic knowledge is critical in postmortem forensic analysis. Morewitz & In Goldstein (2013) suggest, “Investigation occurs in suspected drug intoxication cases that are not readily diagnosed at the autopsy.” Moreover, the unexplained death cases are under the control of experienced medics.  Occasionally, toxicology studies in such cases are essential in determining the causation of death as well as the making of the final decision. In intravenous drug deaths, a forensic scientist may examine the point where recent injections were conducted, and oral intoxications may be evidenced by the availability of unabsorbed tablet fragments in the stomach. “The only other anatomic findings are pulmonary congestion and edema” (Gavin, 2014).

In case the cause of death is unexplained, the toxicology knowledge applies to rule out poisoning, drug overdose or therapeutic misadventure. Some cases present substantial evidence to indicate drug overdose, drug poisoning, or the suicide notes and drugs containers that help the medical examiners to make valid decisions. Death from arson, exposure to poisonous fumes from incomplete combustion of materials gives a direct link to the intoxication of carbon monoxide. In such cases, forensic toxicology can be helpful to support investigative findings. Conversely, the problems derived from the death of young or middle-aged person without suicide notes or the physical evidence of poisoning or overdose may be resolved with the help of toxicology testing and interpretation.

While an investigation at the scene may indicate the causative agent, toxicology laboratory analysis is needed to identify and quantify the substances present in the biological specimens to determine whether these drugs caused or contributed to the death. “Forensic laboratories utilize varying analytical methodologies, but the commonly used are immunoassay and chromatographic method” (Kobilinsky, 2012). Gas chromatography is normally used in analyzing the toxic levels in Alcohol. Enzymatic and colorimetric methods normally apply in the initial or screening test. The tests on carbon monoxide may occur through spectrophotometric differentiation between oxyhemoglobin, reduced hemoglobin, methemoglobin, and carboxyhemoglobin. Similarly, Cyanide testing involves colorimetric quantitation and diffusion.

Toxicologist investigations are also important in deaths other than drug intoxications, such as homicides and accidental deaths. Many medical examiners routinely perform drug screens on all homicides, for instance, homicides related to drugs, drugs abuse, and pharmacologic effects of drugs.


Although it is common to think that forensic toxicology is interested only in the consumption of illicit drugs such as heroin, some therapeutic drugs such as antidepressants and muscle relaxants have a significant behavioral effect. The behavioral toxicologist must evaluate the effects of therapeutic drugs when administered in a prescribed manner for their normal medical applications, as well as when they are incorrectly administered or abused.

The toxicological analysis of the behavioral effects of drugs should also consider the metabolic profile of the suspected drug or alleged substance. In Morewitz & In Goldstein (2013) assert, “The presence of active metabolites is certainly important in evaluating the behavioral effects of drugs because they contribute to the parent drug’s effects.” The presence of inactive metabolites, although exerting no behavioral effects themselves, may generate some information about the approximate time that drug was used.

The specimen mostly used for establishing does and concentration relationships is blood. Since blood is the most intimately in contact with the central nervous system (CNS), it provides the best information concerning how a drug, it active metabolites, and their concentrations are related to performance impairment. Alternate specimens such as urine, sweat, and hair are becoming increasingly popular, but it is unlikely that a direct behavioral relationship can be established using these specimens.


Gavin, H. (2014). Criminological and forensic psychology.

In Morewitz, S. J., & In Goldstein, M. L. (2013). Handbook of forensic sociology and psychology.

Kobilinsky, L. F. (2012). Forensic chemistry handbook. Hoboken, N.J: John Wiley & Sons.