Forensic toxicology is the use of toxicology and related disciplines such as analytical chemistry, pharmacology, and clinical chemistry to aid medical or legal investigations of death, poisoning, and drug use. It involves the analysis of biological samples for the presence of toxins, including drugs, to determine the type of substances present in an individual and if the amount of those substances is consistent with a therapeutic dosage or is above a harmful level. The primary concern for forensic toxicology is not the legal outcome of the investigation or the technology utilized, but rather the obtention and interpretation of results.
Forensic toxicologists work with pathologists, medical examiners, and coroners to help determine the cause or circumstances of death. They analyze various kinds of samples, including blood, urine, gastric contents, oral fluids, hair, and tissues, to determine which toxic substances are present, in what concentrations, and the probable effect of those chemicals on the person. They must consider the context of an investigation, in particular any physical symptoms recorded, and any evidence collected at a crime scene that may narrow the search, such as pill bottles, powders, trace residue, and any available chemicals.
Forensic toxicology can be separated into three disciplines in the United States: postmortem toxicology, human performance toxicology, and forensic drug testing (FDT) . Postmortem toxicology includes the analysis of biological specimens taken from an autopsy to identify the effect of drugs, alcohol, and poisons. Human performance toxicology involves the analysis of biological specimens to determine the effect of drugs and alcohol on a persons ability to perform tasks such as driving or operating machinery. FDT involves the analysis of biological specimens to determine the presence of drugs in individuals who are subject to drug testing, such as athletes or employees.
Forensic toxicologists use highly sophisticated instruments, chemical reagents, and precise methodologies to determine the presence or absence of specific substances in the sample. They must document every step of the process and take care to follow rules regarding chain of custody for physical evidence. The field of forensic toxicology has grown to include drug and alcohol testing for employers and traffic enforcement officials, testing animal samples for wildlife criminal investigators, and testing for “date rape” drugs and performance-enhancing substances. Forensic toxicologists also work on cases involving environmental contamination to determine the impact of chemical spills on the environment.
