Forensic toxicology deals with the study of the adverse effects of drugs and chemicals on biological systems, and the interpretation of those results for legal purposes.

Forensic toxicologists perform scientifically validated tests to determine the presence and/or level of drugs or chemicals in the body. The toxicologist may perform tests on a number of bodily fluids including blood, urine, vitreous humour (eye fluid), saliva or tissues and most commonly the liver. There are different types of investigations that may have samples submitted for Toxicology testing.

Impaired driving investigations aim to determine the level of alcohol or drug(s) in the body. These levels are compared to legislated levels to determine if an offence has been committed or to scientific literature to predict human performance, specifically driving ability under the effects of drugs. Drug facilitated sexual assault investigations may aim to determine the presence of any sedating or mood altering drugs within the victim’s body.

Death or homicide investigations may aim to determine what drugs are in the victim’s body at the time of death to determine the individual’s frame of mind. Drug levels can also be used to determine if an individual died from a drug overdose.

A forensic toxicologist may work in a laboratory which focuses primarily on cases proceeding within the criminal system (e.g. RCMP Forensic Laboratory) or in a laboratory which provides information to the coroner/medical examiner and pathologists, for determination of a cause of death. Laboratories may also provide both services (e.g. 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.