Forensic Toxicology

Toxicology Discipline

The Toxicology Discipline of the Alabama Department of Forensic Sciences provides assistance to local, county, state and federal law enforcement agencies in Alabama in death and criminal investigations. This assistance includes laboratory analyses of biological specimens for the presence of drugs and poisons. The findings of these analyses may then be used to establish cause and manner of death or to ascertain or to explain impairment or performance of an individual pursuant to criminal activity.

The Toxicology Discipline currently receives and completes in excess of 4000 cases annually. Specimens are submitted from autopsies conducted by medical examiners associated with the Department. The bulk of the remaining specimens are submitted by local police and county sheriff departments, Alabama State troopers and county coroners. Any law enforcement agency with jurisdiction in the State of Alabama may submit specimens for examination. The goal for turnaround is to complete 100 % of non-homicide cases within 90 days and 100 % of homicide cases within 60 days of receipt in the laboratory. The current average turnaround time is 50 days from receipt in the laboratory with fewer than 5% exceeding 90 days. Current casework based on the nature of the investigation is represented below.

Scope of Analysis

The Toxicology Discipline conducts qualitative and quantitative analyses. Qualitative analyses are used to identify a particular substance in a specimen but not to determine how much of the substance is present. Quantitative analyses are used to both identify a particular substance and to establish how much is present. Quantitative analyses are more complicated than are qualitative analyses because the procedures must be calibrated and controlled for each particular drug. Because of this added complexity and for the sake of timeliness, the Toxicology Discipline may report qualitative findings without quantification or it may limit analyses to specimens where such findings can be reasonably interpreted. Quite often, the mere presence of a substance in a specimen is sufficient to answer the question whether it was consumed.

The Toxicology Discipline routinely conducts quantitative analyses for ethanol (alcohol) and related volatiles such as acetone, methanol and isopropanol.  Headspace/gas chromatography (HS/GC) is employed for this purpose.  This method may be applied to both liquid (blood, urine, etc.) and non-liquid (tissues, etc.) specimens and is specifically calibrated and controlled for these volatile substances.  Non-biological specimens such as beverages may be analyzed as well.  The Toxicology Discipline confirms positive findings by repeat analysis with the same or another specimen collected from the same subject.

The Toxicology Discipline also routinely conducts qualitative analyses for prescribed and non-prescribed drugs.  Some of the many drugs and drug classes detected during these analyses include the sympathomimetic amine class (amphetamine, methamphetamine, MDMA, ephedrine, etc.), cocaine and metabolites, opiate class (morphine, codeine, hydrocodone, oxycodone, etc.), benzodiazepine class (diazepam, alprazolam, etc.), barbiturate class (phenobarbital, butalbital, etc.), cannabinoids (from marijuana), other analgesics (propoxyphene, methadone, tramadol, etc.), antidepressants (amitryptyline, Prozac®, etc.), muscle relaxants and sedatives (Soma®, zolpidem, etc.).  The Toxicology Discipline also routinely conducts analyses for carbon monoxide (as carboxyhemoglobin).  This list is not intended to be complete, rather it represents only a small sampling of the substances that comprise the scope of analysis.  Please contact a laboratory for more specific information.

Because toxicological findings are used in Court, the analyses are conducted according to legally defensible practices and methods.  All submitted specimens are maintained under chain-of-custody and in a secure environment to preserve the material for the intended analyses.  Analyses are conducted in two phases.  The presumptive phase is intended to provide indications whether a particular drug or drug class is present.  Specimens that appear to be presumptively positive are then subjected to the confirmation phase, which is intended to provide more definitive identification of the drug.  Confirmation analyses are typically conducted with methods that have greater specificity than do presumptive analyses and which may examine the chemical structure of the substance as a means of identifying it.  Gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC-MRM MS) are routinely employed for this purpose.  If a specimen is initially subjected to analysis with GC/MS or LC-MRM MS, a confirmatory analysis may be conducted by repeat analysis with another specimen collected from the same subject.  Positive drug findings are reported only when they are confirmed.

Interpretation of Toxicological Results

Toxicological analyses represent a tool for assessing the degree of impairment exerted by a drug or combination of drugs on a consumer.  Because the ultimate degree of impairment is death, toxicological findings are used as part of the determination of cause and manner of death.  In this light, the presence of one or more drugs at concentrations significantly higher than those expected following therapeutic doses may be considered, along with other anatomical conditions or defects, in determining whether drug consumption caused or contributed to death.  Conversely, the lack of adequate drug in a subject may indicate non-compliance to therapy and allow for the conclusion that death was due to conditions that might otherwise have been survivable.

Toxicological findings may be used to assess lesser degrees of impairment such as the performance of an individual pursuant to criminal activity.  A common application is to determine whether an individual has been driving under-the-influence of ethanol (alcohol, DUI) and/or drugs (DUID).  Toxicological findings may also be used to determine whether the actions, behavior or demeanor of a homicide victim or suspect were affected at the time of the incident and, thereby, offer potential mitigating circumstances in adjudication of the crime.

In order to establish impairment from toxicological findings, such findings must include a relevant substance present within a relevant specimen.  The reason for this is that drugs exert their pharmacological effects when they are present in a target organ or organ system.

A relevant (active) substance is one that exerts pharmacological activity and parent drugs typically fit this description.  However, once ingested, normal biochemical processes within the body act upon and convert parent drugs into metabolites, which may or may not exert the same pharmacological activity as the parent drug.  Furthermore, metabolites may co-exist with the parent drug or they may persist after the parent drug has been converted or eliminated.  Consequently, only parent drug and active metabolites are relevant substances for establishing impairment.  That is not to say that the identification of inactive metabolites is without value.  Such may allow for, among other things, the distinction between acute and chronic drug ingestion.

The most significant target organs of forensic toxicological interest are the brain and nerves that comprise the central and peripheral nervous systems.  Blood circulates within the nervous systems and as such, is the most recognized, relevant specimen.  Urine, which is commonly subjected to toxicological analyses, does not circulate within the nervous systems and, therefore, does not qualify as a relevant specimen with which to establish impairment from a toxicological finding.  Nevertheless, a toxicological finding with urine may be used to establish consumption and, depending upon the individual case and other evidence at hand, may be used to explain certain observed behavior.  Toxicological findings in tissues may be considered in postmortem cases where sufficient medical literature exists to relate such findings to death or impairment.

The effects of ethanol and drugs are continuous and progressive, which means generally, the greater the dose, the greater the effect.  However, the progression of effects differs amongst individuals because overall impairment is the collection of all the mental and physical functional responses to ethanol and drugs which are not uniform.  For example, with depressant drugs, low doses will impair one's inhibitions, which results in outwardly and visibly excited behavior.   However, greater doses overcome this excitation and result in lethargy, sleepiness, coma and death from respiratory depression.  The point where one subject appears excited versus lethargic or lethargic versus comatose depends upon the collective degree to which all of the subject's mental and physical functions are affected.  This difference is the result of individual biological characteristics and tolerance (the resistance to some effects and the physiological dependency on continued doses acquired through frequent and repeated exposure to ethanol and/or drugs).  Therefore, while it may be said that people respond differently to drugs (and ethanol), the truth is that people respond the same but to different degrees.

There is a well-documented direct relationship between one's blood ethanol concentration and one's ability to operate a motor vehicle.  Such relationship is reflected in the DUI per se laws.  With drugs, there is also a well-documented direct relationship between one's blood drug concentration and the effect on one's task performance. However, because the degree of effect amongst individuals is so much more varied with drugs  than with ethanol, definitive per se limitations are more difficult to establish scientifically and to apply legally.  Some jurisdictions have zero-tolerance statutes for DUID whereas others employ the expertise of a toxicologist in Court  to reconcile performance impairment with the presence a drug or combination of drugs.

Submission of Specimens

Specimens may be submitted to the Toxicology Discipline in person or by common carrier such as the US Postal Service, UPS, FedEx, etc.  The Department distributes kits, which contain the appropriate tubes, needles, seals, documentation, instructions and address labels for this purpose.  There are two types of kits, one for collecting specimens from live subjects and a second for postmortem specimens and is intended for Coroners.  Individual specimens should be labeled with the name of the subject/suspect and packages should be sealed and initialed.  Submission documentation should be sufficiently completed to allow the laboratory to determine the nature of the case and the most appropriate examinations to conduct. Completed documentation should be inserted into the pouch affixed to the outside of the kit. Kits should be sealed and initialed then submitted to the laboratory.

The antemortem kit is intended for collection of specimens from live subjects and is appropriate for submission of specimens in DUI investigations. This kit contains two 10-mL gray-stopper blood collection tubes and one 100-mL plastic urine cup. The kit also contains a needle, alcohol-free cleansing wipes and seals. The tubes contain sodium fluoride preservative and potassium oxalate anticoagulant. Two completely-filled tubes are recommended for a complete scope of analyses. Urine collection is optional, but highly recommended, especially when gammahydroxybutyrate (GHB) is suspected or there is a delay of more than several hours in collecting the specimens.

Antemortem (DUI) kits bear an expiration date which is intended to relate to the vacuum within the blood collection tubes. Use of expired tubes will not invalidate findings determined with these specimens; however, vacuum within the tubes may be reduced, which may reduce the volume of specimen collected and, accordingly, limit the scope of analyses which may be conducted. It is recommended that expired tubes be replaced with similar tubes from hospital stock. Kits are so marked.

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Antemortem (DUI) Kit Antemortem (DUI) kit contents Properly packaged antemortem
 (DUI) Kit
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Properly sealed blood
Low volume specimen Properly sealed kit

A postmortem kit is intended for Coroners for collection of specimens from deceased subjects. This kit contains two 30-mL screw-cap containers, one for blood and the other for urine. The kit also contains a collection needle and syringe and seals. Both containers should be completely filled with the respective specimens for a complete scope of analyses.

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Postmortem kit contents Postmortem kit needle and syringe Postmortem kit containers
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  Properly sealed postmortem specimens  

By submitting specimens, the investigating agency acknowledges that the Toxicology Discipline will conduct examinations at its discretion pursuant to current policies, procedures and capabilities and the nature of the case as determined from information provided by the submitter.  The investigating agency further acknowledges that specimen volume, condition and relevance may limit the number or types of examinations which may be conducted and that whereas the Toxicology Discipline and the Department will exercise all due diligence to preserve submitted materials, such are biological in nature and, therefore, perishable.

Toxicological Analysis Request Form DFS-59

The Alabama Department of Forensic Sciences Toxicology Discipline operates in the Birmingham/Hoover Regional Laboratory.

Alabama Department of Forensic Sciences
Toxicology Section Birmingham/Hoover Regional Laboratory

2026 Valleydale Road
Hoover, AL 35244-2095
Tel (205) 982-9292
Fax (205) 403-2025
Section Chief: Jason S. Hudson, Ph.D
Toxicology Discipline Chief: Curt E. Harper, Ph.D.

For more information on Forensic Toxicology, please click on the links below.

American Academy of Forensic Sciences
Society of Forensic Toxicologists
National Library of Medicine PubMed Search Engine
Journal of Analytical Toxicology
Journal of Forensic Sciences
Forensic Science International
American Board of Forensic Toxicology
Forensic Toxicologist Certification Board