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Forensic Toxicology

Forensic toxicology refers to the use of toxicology for the purposes of the law. It is considered a hybrid of analytical chemistry and fundamental toxicology.

 

History of forensic Toxicology

Until the 1700s convictions associated with homicidal poisoning were based only on circumstantial evidence rather than the identification of the actual toxicant within the victim. In 1781, Joseph Plenic stated that the detection and identification of the poison in the organs of the deceased was the only true sign of poisoning. Years later, 1813, Mathieiv Orfila (considered the father of toxicology) published the first complete work on the subject of poisons and legal medicine. By 1836, James M. Marsh developed a test for the presence of arsenic in tissue. Then, in 1839, Orfila successfully used Marsh's test to identify arsenic extracted from human tissues. By 1918, the Medical Examiner's Office and Toxicology Laboratory was established in New York. The chief forensic toxicologist was Alexander O. Gettler who is considered the father of American toxicology.

INVESTIGATION OF TOXICITY-RELATED DEATH/INJURY

The basic phases in conducting an investigation of a suspected toxicant-induced/related death can be viewed as follows:
 
  1. Collection of information and specimens:
When collecting the specimens, many different body fluids and organs should be collected since toxins have different affinities for body tissues and therefore multiple extractions (for specific analyses) may be needed
  1. Documentation process

Labelling and all handling documentation must exist from the beginning of data /specimen collection of analysis. The name of the victim (if known) is recorded along with the name of the medical examiner.The condition of the body when found is described and the date of death is recorded. Additionally the date of request of toxicological analyses is also stated on the report.

Each collected specimen is identified as well as the tests to be performed. In the results section it is necessary that the analyst for each test signs the form identifying the actual results for the tissue tested and the date the results were obtained.

  1. Forensic Toxicological Analysis

 

  •  necessary to know the nature of the toxicant to test.
  •  Furthermore toxicant biotransformation must be taken into account when doing the analyses and making interpretations

Drug Concentrations and Distribution

  • As a rule, the highest concentrations of a poison are found at the site of administration. A large quantity of drug in the GI tract and liver indicates oral ingestion. The gastrointestinal tract may contain large amounts of unabsorbed toxicant. Cases that involve the oral administration of toxicants indicate analysis of GI contents.
  • Blood and tissue analysis is necessary and would still be paramount.
  • Higher concentrations of drug or toxicant in the lungs compared to other tissues may indicate inhalation, compounds located in tissue surrounding an injection site indicates a fresh intramuscular or intravenous injection.
  • Urine analysis is also of great value since the kidney is the major organ of excretion for most toxicants.
  • The liver is usually the first internal organ to be analyzed. After GI tract absorption, toxins are transported to the liver. This is a major center of compound biotransformation
  • Finally blood specimens must be collected with care and thought.When collecting blood, it is advantageous to collect both heart and peripheral blood specimens. Postmortem blood drug concentrations are site-dependent. This site dependency is referred to as 'anatomical site concentration differences' or 'postmortem redistribution.'

 

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