Carbon monoxide poisoning can occur endogenously from biochemical reactions or exogenously from incomplete combustion of fuels. CO binds strongly to hemoglobin, preventing oxygen transport. Symptoms include headache, weakness and confusion. At autopsy, cherry-red lividity may be seen due to carboxyhemoglobin formation. Blood analysis uses spectroscopic, chemical and instrumental methods to detect elevated carboxyhemoglobin levels above 50-60%, which can be lethal. Precise quantification is important for forensic investigations into causes of death.

1. Carbon Monoxide
Poisoning
NAME – MOHIT
CLASS – M.Sc. Forensic science(II)
Roll no. - 16151027

2. CONTENTS
 Introduction
 Sources of CO
 Fatal Dose
 Toxicokinetics
 Mode of Action
 Autopsy Features
 Forensic Issues
 Sample Stability and Storage
 Analysis
 References

3. INTRODUCTION
 Carbon monoxide is a compound of carbon and oxygen
 Synonyms – Carbonic Oxide, Carbon Oxide, Water gas, Flue gas
 Chemistry –
 Specific gravity-0.967
 Colourless
 Odourless
 Tasteless
 Non-Irritating
 Lighter than Air
 Extremely Stable
 Extremely Flammable

4. SOURCES of CO
 Endogenous
 Exogenous
 Methylene Chloride

5. ENDOGENOUS
 Results from biochemical reaction (Haeme Degradation, Lipid
Peroxidation)
 Never reach toxic levels on its own
 Normal Individual – 1-5%
 Smokers – 5-8%
 Levels increase in case of :
 Haemolytic Anaemia
 Sepsis
SOURCES(cont.)

6. SOURCES(cont.)
EXOGENOUS
 Incomplete combustion of almost any form of fuel or hydrocarbons
hydrocarbons (wood, charcoal, gas, kerosene)
 Automobile exhaust
 Fires
 Tobacco smoke
 Heaters
 Camp stoves

7. METHYLENE CHLORIDE
 Paint and adhesive remover
 Used to decaffeinate coffee or tea
 Can be absorbed through skin
 Converted to CO in liver after inhalation
SOURCES(cont.)

8. FATAL DOSE
 COHb level in blood exceeding 50 to 60 % is potentially lethal
 A CO concentration of 5000 ppm in air is lethal to humans
after five minutes of exposure

9. TOXICOKINETICS
 The lungs avidly absorb CO which combines with
haemoglobin(85%) and myoglobin (15%)
 Elimination occurs exclusively through the lungs

10. MODE OF ACTION
 CO binds to haemoglobin with an affinity 200-250 times
greater then that of oxygen to form Carboxyhaemoglobin
(COHb)
 CO interfere with cellular respiration by inactivating
mitochondrial cytochrome oxidase

11. SYMPTOMS
 Dull headache
 Weakness
 Nausea
 Vomiting
 Confusion
 Dizziness
 Difficult breathing

12. AUTOPSY FEATURES
(A) Lividity of cherry-red or bright
pink colour, as a consequence of COHb
formation
(B) Smoke in the face, nostrils and
mouth is suggestive of CO poisoning

13. Cont.
(D) Smoke soot covering the
larynx, trachea and bronchi
(C) Cutaneous bullae

14. FORENSIC ISSUES
 Circumstances seem to point irrefutably to carbon monoxide
poisoning, but the blood analysis shows low or normal COHb
levels.
 Due to the time gap between analysis, hospital biochemistry
laboratory results and forensic science laboratory results do
not agree.

15. SAMPLE STABILITY AND STORAGE
 Freezing the samples and thawing them only at the time of
analysis
 Anti-coagulated blood should ideally be sealed into vials with
a minimum of air space
 Stored deep frozen or atleast at 3°C prior to assay
 Reducing agent – sodium dithionite

16. ANALYSIS
 SPECTROSCOPIC TEST — The spectrum of the blood will show
two absorption bands similar to those of oxyhaemoglobin, but
placed nearer the violet end. The addition of ammonium
sulphide does not alter the spectrum.
 HOPPE-SEYLER’S TEST — Caustic Soda of specific gravity 1.3 if
added to :
 Normal blood - Greenish colour
 Blood with Carbon Monoxide – Bright Red colour

17. ANALYSIS(cont.)
 KUNKEL’S TEST — The blood, diluted with 4 volumes of water, is
mixed with 3 times its volume of 1% tannic acid solution and
shaken well.
 Carbon Monoxide blood forms a Crimson-Red coagulum, which
retains its colour for several months.
 Normal blood forms a coagulum which is at first red, becomes
brown in the course of one to two hours and then becomes Grey in
in 24 to 48 hours.
 The blood saturated even with 10% Carbon Monoxide responds
responds to this test.

18. ANALYSIS(cont.)
 POTASSIUM FERROCYANIDE TEST — 15 c.c. Of blood is mixed
with an equal amount of 20% potassium ferrocyanide solution
solution and 2 c.c. of dil. acetic acid and shaken gently.
 Blood with carbon monoxide - bright red coagulum
 Normal blood - dark brown coagulum

19. INSTRUMENTAL METHODS
METHODS PRINCIPLE PROBLEMS
Derivative spectroscopy Use of derivative
spectrometry to eliminate
non-specific interference
Strict control over timing
of reading essential
Fourier transform infrared
spectrophotometry
Absorbance measurement at
characteristic bands
Not generally available in
clinical laboratories
GC-TCD Chemical liberation of carbon
carbon monoxide from blood
blood and direct or indirect
measurement of gas
Very precise but complex,
more time consuming

20. cont…
AVOXIMETER 4000
 Allow faster results(in less than 10 sec) to help legal system in closing
cases
 Low blood volume required
 Portable
 Accurate analysis of COHb with refrigerated sample(4°C) for at least 6

21. REFERENCES
 Blyth A W, Blyth M W, Poisons: Their Effects And Detection,
4th Edition, Charles Griffin And Company Ltd., 1906
 Dinis-olivery R J, Carvalho F, Magalhaes T, Santos A,
Postmortem Changes In Carbon Monoxide Poisoning, Clinical
Toxicology 2010; 48 : 762-763
 Modi J P, A Textbook Of Medical Jurisprudence And
Toxicology, 6th Edition, Butter Worth & Co. (India) Ltd., 1940
 Penney D G, Carbon Monoxide Toxicity, 2nd Edition, CRC
Press LLC, 2000
 Pillay V V, Modern Medical Toxicology, 4th Edition Jaypee
Brothers Medical Publishers (P) Ltd, 2013