Forensic toxicology

1. Seema Bansal

2. HISTORY
 50000 BC: used poisonous plants for hunting
 1500 BC: written evidence indicated opium, curare
and metals were used for hunting
 Mathieu Orifila: father of forensic toxicology,
published Traite des Poisons, in 1814.
 Jean Servais Stat: isolated nicotine from dead man’s
tissue
 James M. Marsh: test for presence of arsenic in tissues
in 1836
 Medical examiner’s office and toxicology laboratory
established in New York in 1918

3. TOXICOLOGY
 Science of poisons
 Toxicology is the study of the toxic or harmful effects
of chemicals on humans
 Involves the identification of the substances involved.
 Paracelsus is the Father of Toxicology. According to
him “All things are poison, nothing is without poison,
what matters is the dose”

4. Poison: Any substance which when administered in
living body through any route (Inhalation, Ingestion,
surface absorption, etc) will produce ill-health or
death by its action which is due to its physical,
chemical or physiological properties. Eg: sulphuric
acid, arsenic etc.
Drug (WHO 1996): Any substance or product that
is used or intended to be used to modify or explore
physiological systems or pathological states for the
benefit of the recipient.
Eg: parecetamol, salbutamol, insulin

5. FORENSIC SCIENCE
 Forensic: synonym for “legal”
or “related to courts”
 Answer questions of interest to
a legal system
 It is concerned with the
recognition, identification,
individualization, and
evaluation of physical
evidence.

6. Toxicology is defined as the study of the adverse
effects of chemicals on living organisms.
Forensic toxicology is defined as the application of
toxicology for the purposes of the law.
Postmortem forensic toxicology.
Human performance toxicology.
Forensic drug testing.
FORENSIC TOXICOLOGY

7. FORENSIC TOXICOLOGY
 Hybrid of analytical chemistry and fundamental
toxicological principles concerned with the
medicolegal aspects of the harmful effects of
chemicals on living system.
 Toxicological principles are:
 Study of alcohol, drugs and poisons, including their
chemical composition, preparations and
identification.
 Knowledge about the ADME of above substances
and the factors which determine drug safety and
effectiveness.

8. FORENSIC TOXICOLOGIST
 Members of medico legal team
 Specialized scientists
RESPONSIBILITIES:
 Collection of evidence
 Preservation of samples
 Investigation
 Oral / written reports

9. DEATH SCENE IN LAB
Medico legal investigation team
 The homicide investigator
 The medical examiner
 The forensic pathologist
 The forensic toxicologist
 Proper labeling
 Storage (for collection/ preservation)

10. COLLETION AND
PRESERVATION OF SPECIMENS
 Obtain
 Appropriate container
 Sealing
 Dated & signed
 Taken to laboratory
 Receiving by toxicologist(signed, date and time
recorded)
 Chain of possession must be intact, guaranteeing
complete chronological accountability

11. TOXICOLOGY WORKSHEET

12. TISSUES REQUIRED FOR
ANALYSIS
 BLOOD: 100 ml sample sufficient
Care taken to ensure freedom from
contamination
Heart blood preferred, peripheral blood accepted
 BRAIN: 50 g
Demonstration of alcohol and volatile poisons
KIDNEY: equivalent of one kidney
 Choice for most metals and sulphonamides

13. •LIVER: 100g sample
Site of biotransformation-higher levels found.
•LUNG: 100g
Useful in fatalities due to substance inhalation.
•BONE: 100g
Pesticide or metal suspected.
•HAIR AND NAILS:
chronic metal poisoning suspected.
•URINE:
 available urine collected, if empty, entire
bladder submitted.
Microsugar and acetone determination.

14. •BILE: removed intact
Important route of elimination for many
drugs(morphine, methadone)
•STOMACH CONTENTS:
tablets and capsules in overdose case
Volume of contents recorded

15. LABORATORY ANALYSIS
 Colorimetric screening tests
 Thermal desorption
 Thin layer chromatography
 Gas chromatography
 High performance liquid chromatography
 Enzyme immunoassay
 Atomic absorption spectroscopy

16. DRUG ANALYSIS

17. APPLICATIONS
Identify potential suspects by DNA matching.
Identify crime & catastrophe victims.
Establish Paternity & family relationship.
Identify endangered & protected species.
Detect bacteria & other organism that can pollute
environment.
In transplant programs.

18.  Human performance toxicology is also referred to as
behavioral toxicology; study of human behavior
under the drug influence.
.
 Ethanol and driving
History
Behavioral effect
Specimen
HUMAN PERFORMANCE
TOXICOLOGY

19. ETHANOL TOXICOLOGY
• Cardiovascular System
• Central Nervous
System
• Gastrointestinal Tract
• Kidney
• Liver
ADR OF ETHANOL:

20. Henry’s Law
Ethanol in breath Vs ethanol in blood
2100 to 1 ratio
2300 to 1 ratio
Types of Analyser
Chemical
Reaction of ethanol with potassium
dichromate/sulfuric acid solution
Colored solution that results is measured
spectrophotometrically
IR spectrophotometry
Electrochemical oxidation - fuel cell
BREATH ETHANOL TESTING
Theory

21. BLOOD ETHANOL TESTING
Chemical
 Screening
 Quantitative
 Disadvantage -
aldehydes and
ketones will interfere
with the test
 Enzymatic
• Conversion of NAD to
NADH by ethanol (serum,
urine and whole blood)
 Measured
spectrophotometrically
at 340 nm
• Same reaction with a blue
dye (thiazoyl blue) (serum,
urine, fresh blood and
postmortem blood)
 Measured with a
fluorometer

22. Gas Chromatography
•Can measure ethanol in a wide
range of specimens
•Can distinguish ethanol from
other alcohols, aldehydes and
ketones
•Two common methods
•Head space
•Direct injection
ACETALDEHYDE
(1.414
min.)
EHTANOL
(1.787
min.)
2-PROPANOL
(2.804
min.)
MEK(ISTD)
(5.584
min.)
ACETONE
(2.462
min.)
0 6
BLOOD ETHANOL TESTING

23.  Blood alcohol concentration:
 10-50 mg/dl: Impairment detectable by special tests
 30-120 mg/dl: Beginning of sensory-motor
impairment
 90-250 mg/dl: Sensory-motor in coordination ;
impaired balance
 180-400 mg/dl: Increased muscular in coordination;
apathy; lethargy
 250-400 mg/dl: Impaired consciousness; sleep; stupor
 350-500 mg/dl: Complete unconsciousness; coma
 450 and greater mg/dl: Death from respiratory arrest
ETHANOL IMPAIRMENT
ASSESSMENT

24. Drug Recognition Evaluation - 12 Steps
Breath alcohol test
Interview of the arresting officer.
Preliminary examination of the suspect.
Examination of the eyes.
Divided attention psychophysical tests.
Vital signs examination.
Dark room examination.
Examination of muscle tone.
Examination for injection sites.
Suspect’s statements and other observations.
Opinion of the evaluator.
Toxicological examination.
FORENSIC DRUG TESTING

25. REFERENCES
 Wennig R. Forensic Toxicology. Encyclopedia of Life
Sciences
 Hodgson E. A Textbook of Modern Toxicology.2004(3):
403-406
 Katzung BG, Masters SB, Trevor AJ. Basic and Clinical
Pharmacology. (2012)12: 69-77
 Journal of forensic toxicology and pharmacology; 2013