Toxicology

Toxicology is the study of adverse effects of drugs and chemicals on biological systems.  Forensic toxicology involves the application of toxicology for the purposes of the law, or in a medicolegal context.  A forensic toxicologist answers questions such as:

  • Did prescription or illegal drugs cause or contribute to this person’s death?
  • Was this person impaired by drugs or alcohol while they were driving? or,
  • Was a drug used to facilitate a criminal act?


Answering questions like these often requires forensic toxicologists to work with, and share information with, law enforcement, forensic pathologists, death investigators, crime scene investigators, clinicians, other forensic scientists, and legal professionals.

Scope of Work

The field of forensic toxicology involves three main sub-disciplines: postmortem forensic toxicology, human performance toxicology, and forensic drug testing.  These specialized fields offer a variety of exciting career paths.  In postmortem forensic toxicology, forensic toxicologists work with pathologists, medical examiners, and coroners to help establish the role of alcohol, drugs, and poisons in the causation of a death.  The forensic toxicology laboratory identifies and quantifies the presence of drugs and chemicals in biological fluids and tissues that are taken from the body during the autopsy.  A wide array of specimens may be encountered in postmortem toxicology investigations including blood, urine, vitreous fluid from the eye, liver, brain, and other tissues, as well as hair and nails.  Once the testing is complete, a forensic toxicologist then interprets these findings.  This information helps a forensic pathologist determine the cause and manner of death.

The forensic toxicologist uses state-of-the-art analytical techniques, such as those used in hospital or research laboratories, to isolate and identify drugs and poisons from complex biological specimens.  This requires knowledge of analytical chemistry procedures and instrumental analysis.  Forensic toxicology laboratories use a variety of different techniques, including gas and liquid chromatography, mass spectrometry, spectrophotometry, and antibody-based immunoassays.  Qualitative and quantitative methods of analysis are used to determine which drugs or poisons are present, and at what concentration.  Forensic toxicologists must have an inquiring mind and the ability to apply their knowledge of chemistry and pharmacology to solve real world puzzles.

Human performance toxicology deals with the effects of alcohol and drugs on human performance and behavior.  Drug and alcohol use can have serious medicolegal consequences and is involved in an array of criminal investigations, ranging from impaired driving, to vehicular assault and homicide, to drug-facilitated crimes such as sexual assault.  Criminal investigation analysis involves the same application of techniques as in the death investigation setting, but specimens are typically collected from living persons.  Blood and urine are commonly encountered, but oral fluid, hair, and other specimens are also used.  Forensic toxicologists are frequently asked to determine the timing and extent of impairment resulting from different patterns of drug and alcohol use.  The interpretation of the test results in this area is the greatest challenge, requiring the application of knowledge from clinical and medical studies and experience in the field, to give an opinion about the effects of a drug or combination of drugs on an individual at the time of a crime or accident.

Forensic drug testing is performed in a wide variety of other settings including the workplace, doping control in sports, probation and parole, as well as compliance monitoring and testing.  The use of drugs by people in the workplace has significant safety and economic consequences.  This is particularly important for people employed in hazardous or safety-sensitive industries such as transportation and the military.  The scope of drug testing is often limited however, compared with human performance or postmortem toxicology, but the throughput of testing can be greater.  Workplace drug testing laboratories may perform tens of thousands of tests per day and many times require specialized configurations of equipment such as multiplexing, which decreases analysis time and improves productivity.  Urine is the most common specimen tested but oral fluid, hair, sweat, and other matrices are also used.  As with all of the forensic disciplines, there is a strong emphasis on record keeping, chain-of custody documentation, stringent quality control, and data management.

In forensic toxicology, the interpretation and communication of the results can be more challenging than the analysis itself.  The results obtained are often determined using scientific tests and procedures that are complex and difficult for most juries and lawyers to understand.  Therefore, a toxicologist must have strong communication skills so the information can be presented fairly and clearly in court.

Education and Training

A bachelor’s degree in the life or physical sciences is the first step towards pursuing a career in forensic toxicology.  A solid background in chemistry and coursework in pharmacology and toxicology are needed.  Many forensic toxicologists have masters or doctoral degrees.  Some enter toxicology after working in, or pursuing education in, other areas such as medicinal chemistry, pharmacology, or clinical chemistry.  While relevant educational requirements are necessary to enter the field of forensic toxicology, training in the laboratory furthers an individual’s knowledge, experience, and ability to provide interpretation of the results.  The American Board of Forensic Toxicology (www.abft.org) offers professional certification to scientists working in the area of forensic toxicology.

Career Opportunities

Forensic toxicology is an exciting and rewarding profession, where science intersects with medicine and the law.  It offers the opportunity to interact with other professionals with wide-ranging backgrounds and expertise.  Forensic toxicologists may work in medical examiner laboratories, crime laboratories, military, government, or private sector facilities. Other career opportunities exist in hospitals, universities, and industry.

The Society of Forensic Toxicology (www.soft-tox.org) is a leading professional society for toxicologists in the United States.  The International Association of Forensic Toxicologists (www.tiaft.org) is another excellent source of international reference materials.  Similarly, there are regional professional organizations that can provide additional resources including the California Association of Toxicologists (www.cal-tox.org) and the Southeastern Association of Toxicologists (www.sat-tox.org).  These websites provide many additional details concerning career opportunities and advances in the field of forensic toxicology.

©2021 American Academy of Forensic Sciences