Forensic Toxicology is a branch of Forensic Medicine dealing with Medical and Legal aspects of the harmful effects of chemicals on human beings. Below given are described the general considerations of Forensic Toxicology useful for Undergraduate and Post-Graduate Student of Forensic Medicine.
Poisoning in India: Suicidal (KCN, HCL, Opium, Barbiturates, organophosphorus, oxalic acid oleander etc), homicidal(arsenic, aconite, thallium, oleander, madar, carbamates, organophosphorus etc.) and accidental poisoning are seen in India. Older poisons like opium and arsenic are replaced by newer poisons. Common homicidal poisons are: Arsenic, Antimony, Oleander, Nux-Vomica, Madar, powdered glass and aconite.
Cattle Poisoning is also common, the poison used are Arsenic, Abrus precatrotius, Yellow oleander, zinc phosphide, nitrates, aconite etc.
Toxicology is the science dealing with properties, action, toxicity, fatal dose, detection estimation of, interpretation of the result of toxicological analysis and management of Poisons.
Poison: A Poison is defined as 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: alphose, sulphuric acid, arsenic etc.
Drug (WHO 1996): Drug is 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: paracetamol, ciprofloxacin, salbutamol, oestrogen, insulin etc.
Clinical Toxicology: Deals with human diseases caused by, or associated with abnormal exposure to chemical substances.
Toxinology refers to toxins produced by living organism which are dangerous to man, eg: snake venom, fungal and bacterial toxins etc.
Chelating Agents: are the substances which act on absorbed metallic poisons. They have greater affinity for metals as compared to endogenous enzymes. The complex of agent and metal is more water soluble than metal itself, resulting in higher renal excretion of the complex.
E.g.: British anti-lewisite (B.A.L., dimercaprol), E.D.T.A. (ethylene diamine-acetic acid), Penicillamine (Cuprimine), Desferroxamine etc.
Ecotoxicology: It is concerned with the toxic effects of chemical and physical agents on living organisms, especially in population and communities within defined population.
Acute poisoning is caused by an excessive single dose, or several dose of a poison taken over a short interval of time.
Chronic Poisoning is caused by smaller doses over a period of time, resulting in gradual worsening. eg: arsenic, phosphorus, antimony and opium.
Subacute poisoning shows features of both acute and chronic poisoning.
Fulminant poisoning is produced by a massive dose. In this death occur rapidly, sometimes without preceding symptoms.
Parasuicide (attempted suicide or pseudicide) is a conscious often impulsive, manipulative act, undertaken to get rid of an intolerable situation.
Culpable Homicide: Sec 299 IPC; Causing death of a person by an act, with the intention of causing such bodily injury and is likely to cause death, or with the knowledge that he is likely, by such an act to cause death.
Antidote: Antidotes are substances which counteract the effect of poison. They are divided into Mechanical, Chemical, Physiological and specific receptor antagonists.
Laws in relation to poison and drugs: Different sections of Indian penal code
related to poisons are as follows
Sec. 272 I.P.C. - Punishment for adulterating food or drink intended for sale, so
as to make the. same noxious, may extend upto 6 months imprisonment of either
term and/or fine upto one thousand rupees.
Sec. 273 I.P.C. - Punishment for selling noxious food or drink may be
imprisonment of either description for a period of 6. months and or fine upto one
Sec. 274 I.P.C. - Punishment for adulteration of drugs in any form with any
change in its effect knowing that it Will be sold and used as un-adulterated drug,
may be imprisonment of either description for a period-of 6 months and or fine.
Sec. 275 l.P.C. - Punishment for knowingly selling adulterated drugs with less
efficacy or altered action serving it for use as unadulterated may be imprisonment
of either description for 6 months and or fine.
Sec. 276 I.P.C. - Punishment for selling a drug as a different drug or
Preparation, may be imprisonment of either description which may extend upto 6
months and or fine. .
Note - In the State of West Bengal, the punishment for these offences described
under sections 272 to 276 may be upto imprisonment for life with or without fine.
Sec. 277 I.P.C. Punishment for fouling water of public spring or reservoir may
be imprisonment of either description which may extend up to a period of 3 months
and or fine.
Sec. 278 I.P.C. - Punishment for voluntarily making atmosphere noxious to
health is fine which . may extend upto five hundred rupees.
Sec. 284 I.P.C. Punishment for negligent conduct with respect to poisonous
substance may be imprisonment of either description which may extend upto 6
months and or fine which may extend upto one thousand rupees.
Sec. 328 I.P.C. :Punishment' for causing hurt by means of poison or any
stupefying, intoxicating or unwhlolesome drug or any other thing with the intent to
commit an offence shall be imprisonment of either description for a term which may
extend to ten years with or without fine.
Sources of Poison:
1. Domestic or household sources - In domestic environment poisoning may
more commonly occur from detergents, disinfectants, cleaning agents,
antiseptics, insecticides, rodenticides etc.
2. Agricultural and horticultural sources- different insecticidws, pesticides,
fungicides and weed killers.
3. Industrial sources- In factories, where poisons are manufactured or poisons
are produced as by products.
4. Commercial sources- From store-houses, distribution centers and selling
5. From uses as drugs and medicines Due to wrong medication,
overmedication and abuse of drugs.
6. Food and drink contamination in way of use of preservatives of food grains or
other food material, additives like colouring and odouring agents or other ways
of accidental contamination of food and drink.
7. Miscellaneous sources- snakes bite poisoning, city smoke, sewer gas
Classification of poisons
1. According to the site and mode of action
(A). local Action
Strong Acid: mineral acid and organic acid
Metallic: Mercuric Chloride
Mechanical: Glass Powder.
Inorganic: weak acid, weak alkalies, Inorganic non-metals, Inorganic metals.
Organic: Chemical preparations, Animal and vegetable origin
(B) Remote Action
i. Somniferous: opium and its alkaloids, Barbiturates.
ii. Inebriant (Intoxicant): Alcohol, ether, Chloroform.
iv. Deliriant: Dhatura, Belladona, Hyocyamus, cannabia indica.
i. Strychnos Nux Vomica
i. Local Anaesthetics: Cocaine, Procaine.
ii. Relaxants (curare).
KCN, NaCN, Digitalis, Aconite, Nicotine, Quinine, Oleander
Asphyxiants: Carbon Dioxide, CO, hydrogen sulphide
Nephrotoxic: Oxalic Acid, Mercury, Cantherides
Hepatotoxic: Phosphorus, Carbon tetrachloride, Chloroform.
Miscellaneous: Food Poisons.
(C). Combined local and remotes action:
Classification of Poison according to motive or nature of use:
1. Homicidal : Arsenic, Aconite, Digitalis, Abrus Precatorius, Strychnos nux
2. Suicidal: Opium, Barbiturate, Organophosphorus, carbolic acid, copper
3. Accidental: Aspirin, organophosphorus, copper sulphate, snakes bite, Ergot,
CO, CO2, H2S.
4. Abortifacient: Ergot, Quinine, Calotropis, Plumbago.
5. Stupefying agent: Dhatura, cannabis, chloral hybrate.
6. Agents used to cause bodily injury : Corrosive acids and alkalies.
7. Cattle Poison : Abrus precatorius, Calotropis, plumbago.
8. Used for malingering: semicarpus anacardium
Ideal Suicidal poison: should be easily available, No bad taste, cause No pain,
cheap, highly toxic, tasteless or pleasant taste, capable of being taken with food or
Ideal Homicidal poison: it should be cheap, easily available, colorless tasteless
odourless, highly toxic, No residual product lest, S/S resembles natural diseases,
No antidote, Shows no post-mortem changes capable of being administered with
food or drink.
Route of Administration/absorbtion:
Oral (commonest) eg: alphos, acids,
Inhalation: gas poison
Parenteral (IM, IV, Sub-Cutaneous, Intra-Dermal)
Natural Orifices other than mouth (Nasal, Rectal, Vaginal, Urethral),
Ulcers, wounds and intact skin.
Fate of poison in body:
A part of the poison taken orally gets eliminated
unabsorbed by means of defecation and vomiting. Before absorption the poison
may exert its effects in the G.I. Tract. When absorbed, the poison reaches different
parts of the body and organs through circulation. Some poisons reach some
tissues easily. Others may not cross some tissue barrier. Cumulative poisons get
accumulated in some organs or tissues. A part of poison is eliminated as such
through different route of elimination. But major part is detoxified or metabolized in
the body and than excreted after exerting its toxic effects on the body. Liver is the
main organ to detoxify or metabolize most of the poisons.
Certain poisons like Chloroform, Phosphorus, Nitrates and Acetic acid disappear
by evaporation or oxidized or destroyed in the body and no trace of them can be
detected in the body of post-mortem is delayed.
Excretion of poisons:
Unabsorbed poisons are excreted through faeces and
vomitus. Absorbed poisons are excreted mostly by urine. A part of volatile poison
is exhaled out. Some portion of poison is excreted through bile, saliva, milk, sweat,
tear, hair and nails.
Factors influencing the actions of a poison in the body.
1. Quantity: A high dose of poison acts quickly and often resulting in fatal
consequences. A moderate dose causes acute poisoning. A low dose may
have sub-clinical effects and causes chronic poisoning on repeated
exposure. Very large dose of Arsenic may produce death by shock without
dose irritant symptoms, While smaller dose than lethal dose produces its
2. Physical form: Gaseous or volatile poisons are very quickly absorbed and
are thus most rapidly effective. Liquid poisons are more rapid than solid
poisons. Some poisonous vegetable seeds may pass through the intestinal
canal ineffective when taken intact due to their impermeable pericarp. But
when taken crushed, they may be rapidly fatal.
3. Chemical form : Chemically pure arsenic and mercury are not poisonous
because these are insoluble and are not absorbed. But white arsenic(arsenic
oxide) and mercuric chloride are deadly poisonous. Barium sulphide is
deadly toxic but barium sulphate is non-toxic.
4. Concentration (or dilution): concentrated form of poison are absorbed more
rapidly and are also more fatal but there are some exceptions too.
5. Condition of the stomach : food content presence of food-stuff acts as
diluent of the poison and hence protects the stomach wall. Dilution also
delays absorption of poison. Empty stomach absorbs poison most rapidly. In
cases of achlorohydria, KCN and NaCN is ineffective due to lack of
hydrochloric acid, which is required foe the conversion of KCN and NaCN to
HCN before absorption.
6. Route of administration : absorption rate is different for different routes.
7. Age: some poisons are better tolerated in some age groups. Opium and its
alkaloids are tolerated better by elderly subjects but badly by children and
infants. Belladonna group of drugs are better tolerated by children than by
8. State of body health: A well built person with good health can tolerate the
action of poison better than a weak person.
9. Presence of disease : In certain diseased conditions some drugs are
tolerated exceptionally well e.g.: sedatives and tranquilizers are tolerated in
very high dose by manic and deliriant patients.
10. Intoxication arid poisoning states - In certain poisoning cases some
drugs are well tolerated, like, in case of strychnine poisoning, barbiturates
and sedatives are better tolerated. Whereas in case of barbiturate poisoning
any sedative or tranquilizer will accentuate the process of death.
11. Sleep - Due to slow metabolic process and depression of other body
functions during sleep, usually the absorption and action of the poison is also
slow. But depressant drugs may cause, more harm during the state of sleep.
12. Exercise - Action of alcohol on C.N.S. is slowed during exercise because
more blood is drawn to the muscles during exercise.
13. Cumulative action of poisons : Preparations of cumulative poisons
(poisons which are not readily excreted from the body and are retained in
different organs of the body for a long time) like lead may not cause any
toxic effect when enters the body in low dose. But when such poisons enter
over a long period of time, may cause harm when their concentration in
different tissue reaches high level due to their cumulative property.
14. Tolerance may develop by individuals on long term exposue to a
15. Idiosyncracy: some persons may react adversely to a particular drug
though the general population tolerates the drug well.
Signs and symptoms:
The signs and symptoms may be different for different poisons and is responsible
on the nature and action of the poison. They can be local, remote or combined and
are will be taught in the individual poisons.
Diagnosis of poisoning
In the Living
1. History of the case as stated by the patient himself
and his/her relatives or friend. Full information about
time of onset of the present illness, Initial symptoms,
progress, relation with food, condition of other
persons taking same food or drink, possible source,
any previous history of poisoning, H/o depression,
quarrel. Also note down the color, smell, consistency,
taste and quantity of the possible poisonous
2. Signs and symptoms.
3. Details of examination.
4. Preservation and laboratory investigation of vomitus,
excreta, stomach wash, scraps from any stains area
on the body, blood, stained part of the clothes,
contents of a doubtful container, left over ant part of
food or drink.
In the Dead:
1. History of the case as stated by police or relatives. H/o 2 or more vital
points (1 how long the victim survived after initial symptoms. 2. any
2. Post-mortem Examination (external and internal)
3. Chemical Analysis : detection of poison in the body fluids.
4. Preservation of viscera and other material for lab. Examination.
Postmortem Findings in Case Of Death Due To Suspected Poisoning
1. Postmortem staining: Deep blue - In case of asphyxiant poisons and aniline.
Bright red or cherry red - In case of CO and HCN poisoning.
2. Deep cyanosis - With opium and cardiac poisons.
3. Early rigor mortis - With strychnine.
4. Early appearance of the sign of decomposition - With H2S gas.
5. Detectable smell - In case of volatile poisons, opium and HCN, KCN or NaCN.
6. Haemorrhagic spots under the skin and mucus membrane: Phosphorus.
7. Ulceration on lips and near the angles of mouth - Corrosive poisons.
8. Stain near mouth and on hands - Nitric acid and copper sulphate.
9. White froth from mouth and nose Opium and its alkaloids. .
10. Blood tinged froth from mouth and nose Organophosphorus compounds.
11. Alopecia, hyperpigmentation and hyperkeratosis - Arsenic poisoning over a long period.
12. Staining, erosion and ulceration near the female external genitalia - Use of
abortifacient agents or torturing agents.
13. Injection marks - Injection of poisons (snake bite or otherwise), sign of treatment.
The G.I.T. should be examined very carefully since signs of
corrosive or irritant poisons are likely to be find therein. These signs are
Hyperemia, softening, ulceration and perforation. Apart from this below given is a
brief note of internal finding in cases of poisoning.
1. Corrosion, ulceration and desquamation of inner aspects of lips, mucus
membrane of mouth and tongue - Corrosive agents.
2. Soft, swollen, sodden, translucent, bleached tongue and mucus membrane of
3. Hardening of mucus membrane - Phenol
4. Phenol Yellowish discoloration - Nitric acid
5. Bluish discolouration - Copper sulphate
6. Carbonization and charring- Conc. Sulphuric acid
7. Chalky appearance and consistency of teeth -:Sulphuric acid
8. Blue lining in the gum - Chronic lead poisoning
9. Swollen gum, loose teeth, foetid smell - Acute mercuric chloride poisoning;
chronic phosphorus poisoning
10. Corrosion, irritation, desquamation and haemorrhage in the inner wall of the
esophagus - Corrosive and irritant poisons
11. Hardening and whitish discolouration In case of Carbolic acid poisoning
12. Discoloration and staining of inner aspects of mouth - With coloured poisons
13. Oesophageal stricture - A complication of sulphuric acid ingestion
(a) Thickening and softening of the wall -Corrosive and irritant poisons
(b) Hard wall- Carbolic acid
(c) - Hard and leathery wall- Formaldehyde
(d) Hyperemia haemorrhageand desquamation of mucus membrane Irritant poison
(e) Laceration and sloughing Corrosive poison
(f) Perforation - H2SO4 and HN3
(g) Yellowish discolouration of mucus membrane - HNO3; Bluish - CuSO4; Slaty grey - HgCl3
(h) Stomach content - Blood - Corrosive and irritant; Yellowish HNO3 Bluish -
CuSO4 Luminous in dark - Phosphorus; Detectable tablet - soneryl; Powder oxalic
acid, white arsenic; Detectable smell - kerosene, alcohol, chloroform,
organophosphorus compounds, chlorinated hydrocarbons, opium, cyanogen,
formaldehyde, phosphorus; Detectable liquid - kerosene.
15. Small intestine - May show irruption, sometimes may show presence of
16. Large intestine - May show ulcerations, as in case of HgCI3 similar in
appearance of ulcers of bacillary dysentery. It particularly involves the ascending
and transverse colons.
17. Liver - Different degenerative changes occur in cases of poisoning with
poisons like phosphorus, carbon tetra-chloride, chloroform, tetrachlorethylene and
many other poisons. The type and extent of the degenerative changes occur
depending on the type of poison, dose, duration of the exposure and physical
condition of the patient.
18. Kidneys - Swollen, reddish, soft, sometime greasy in touch with haemorrhage
in calyces and other degenerative changes - cases of poisoning with mercury,
oxalic ad carbolic acid, phosphorus, cantherides, viper snake venom and many
others. In case oxalic acid poisoning, white powder of oxalate crystals are present
in the tubules and the calyces .
19. Urinary bladder - Haemorrhage in cases of abrus precatorius, viper snake bite
em, cantheride poisoning.
20. Larynx and trachea - Hyperaemic, inflamed -In cases of inhalation of irritating
gases leaking of corrosive agents while ingestion vomiting; froth in the lumen of
trachea and larynx in case of opium and organo:phosphorus poisoning.
21. Chest cavity -Smell of volatile poisons cyanogen, opium etc. can be detected.
22. Lungs - Voluminous, congested, presence of Tardieu's spots - In case of
asphyxiants and inhaled poisons. Cut section gives blood stained frothy-fluid in
case of opium and other asphyxiants.
23. Heart- Presence of subendocardial haemorrhagic spots in cases of arsenic,
phosphorus, mercuric chloride etc.
24. Brain and spinal cord - Congestion and edema of brain and spinal cord in
cases of cerebral and spinal poison (e.g. strychnine: respectively. Brain may be
congested. oedematous with occasional haemarrhagic points at places in cases of
25. Uterus and vagina- Staining, congestion haemorthage, ulceration in cases of
attempted abortion by use of local abortifacient agents.
Preservation of viscera and other materials
In all cases of poisoning
1. Stomach with its full contents.
2. Half of Liver or 500 gms whichever is more.
3. A loop of small intestine.
4. Half of each kidney.
5. Some portion of spleen
In some particular poisons
1. Blood 100ml: in cases of absorbed poisons.
2. Urine 100ml in all cases where blood is preserved.
3. Part of both lungs in cases of Volatile poisons.
4. Heart in case of cardiac poisons.
5. Brain in cerebral poisons.
6. Spinal in spinal poisons.
7. Bones in arsenic and lead.
8. Hair in arsenic and copper.
9. Nails in arsenic.
10. Skin-scrap from areas stained with a suspected poison.
11. Stained areas of dress, suspected packet of poision, strips of tablets recovered from pocket.
For Viscera: absolute alcohol or rectified spirit. Exception: alcohol, chloroform,
chloral hydrate, formaldehyde, ether, phosphorus (alcohol prevents the luminosity
of phosphorus in dark) etc.
Blood should be preserved in fluoride, oxalate, E.D.T.A., gold chloride or citrate
Urine and clothes: without any preservative.
Management of a case of poisoning
Immediate resuscitative (Basic Management) measures in comatose patient should
be adopted to stabilize respiration, circulation and the correct CNS depression.
A) Airway: opening up and cleaning the airways (oral cavity, Nostrils) of
secretions, vomit or any foreign body. Pull tongue forward
B) Breathing : Supplemental oxygen therapy should be administered
C) Circulation: I.V. fluid administration
D) Depression of CNS should be corrected
1. Removal of patient from source of exposure: Patient should be removed
away from the source of poison as quickly as possible.
2. Removal of the unabsorbed poison . In case of contact poison washing of
affected area with soap water with gentle rubbing will be helpful. In cases of
ingested poisons Gastric lavage is useful within 3 hours of ingestion and is
done by stomach tube( Ewald or Boas tube) or by Ryles tube followed by
emesis (physical or by drugs like Ipecacuanha 1-2 gm, mustard oil 1 Tsf in a
glass of water, concentrated salt solution 6%, Zinc Sulfate 1-2gm in water,
apomorphine hcl 1-2ml o 3 mg /ml). In case of injected poison ligature is
applied above the wound. In cases of inhaled poison the patient should be
immediately removed to fresh air.
3. Diluting the poison and delaying the absorption by water or food.
4. Elimination of absorbed poison by increases urination (diuresis), increased
perspiration (diaphoresis), Dialysis, use of chelating agents.
5. Use of specific antidote
6. Symptomatic treatment including safeguarding respiration and maintenance
Counterindications of gastric lavage with stomach tube:
1. In corrosive poisons.
2. Convulsant poisons.
3. Unconscious or semi-conscious patients
4. In infants and children: Ryles tube or infant feeding tube is used.
Antidote: Antidotes are substances which counteract the effect of poison. They
are divided into Mechanical, Chemical, Physiological and specific receptor
Physical or mechanical antidote prevents the action of poison mechanically,
without destroying or inactivating the damaging actions of the poisons. Eg:
adsorbents like activated charcoal, Demulcents like egg albumin, starch or milk,
Diluents like water or milk, bulky food like boiled rice or vegetables.
Chemical antidotes are substances which disintegrate and inactivate poisons by
undergoing chemical reaction with them. Eg: Weak acids and alkali, common salt,
egg albumin, KMNO4 .
Physiological antidote have their own action producing signs and symptoms
opposite to that produced by the poison.
Eg: Naloxone for morphine, Neostigmine for datura or hyoscin group, Barbiturate
Serological Antidote: Anti-snake venom serum for snake bites poisoning.
Universal Antidote: It is a combination of physical and chemical antidotes. When
the exact nature of poison is not known then universal antidote is used which acts
against a wide range of poisons.
Activated charcoal : 2 parts
Magnesium oxide : 1 part
Tannic acid : 1 part
Dose : 1TSF (15gms) in a glass water (can be repeated)
poisons, tannic acid precipitates alkaloids.
1. Strong liquid tea (contains tannic acid) precipitate alkaloid and metallic
2. Starch for iodine.
3. Milk and raw egg for mercury, arsenic, heavy metal.
4. Flour suspension and mashed potatoes can be used in place of activated
5. Milk of magnesia or soap solution for acid poisoning.
6. Orange, lemon juice or vinegar for alkali poisoning.
Chelating agents are the substances which act on absorbed metallic poisons.
They have greater affinity for metals as compared to endogenous enzymes. The
complex of agent and metal is more water soluble than metal itself, resulting in
higher renal excretion of the complex. Eg: British anti-lewisite (B.A.L.,
dimercaprol), E.D.T.A. (ethylene diamine acetic acid), Penicillamine (Cuprimine),
B.A.L. (British Anti-Lewisite, 2-3 dimercaptopropanol) has 2 unsaturated SH
radicals which combines with metal in circulation , thus tissue enzymes are spared.
Usefuls in cases of Arsenic, mercury, copper, bismuth, gold etc
Dose: 3-4 mg/kg BW as a preparation of 10% with 20% Benzyl benzoate in arachis
oil given deep intra-muscular (may cause embolism on I.V. inj.)4 hourly fo0r first 2
days followed by twice daily for 10 days
E.D.T.A. (Ethylene diamine tetra-acetic acid) it combines with sodium to form
sodium salt and then with calcium to form disodium calcium edentate which
combines with free metal and inactivates it biologically. It is best chelate for lead.
Dose for adults 1gm twice daily at 12 hour interval slow I.V. Injection mixed with
5% glucose saline.
Penicillamine: It has stable SH radical which combines with free metal. Dose
30mg/Kg BW/Day in 4 divide doses for 7 days.
Desferrioxamine: It is specific antidote for iron. Dose 8-12 gm orally. For
absorbed iron 2gm I.V. with 50% laevulose solution.
Duties of a Registered Medical Practitioner in connection with poisoning
(a) Try to save the life of the patient and give emergency necessary
(b) If necessary, the patient should be sent to a better hospital, if possible a
government hospital, if the condition of the patients demands and permits the shift.
(c) To take a detailed history of the case as to when and how the symptoms
started what is the progress; whether related to taking of any food or drink ;
whether the number of sufferer is more than one whether any treatment was
already given and whether there is any history of previous poisoning.
(d) The doctor should himself record full history of the case, the signs and
symptoms and progress.
(e) The doctor should collect and preserve the vomitus, stool, urine, clothes
stained with poison or vomitus, doubtful container with remaining part of the
poison, if any, and if necessary blood, for laboratory investigations.
(f) The doctor should arrange for a reliable attendant of his own choice, for _
(g) The doctor should. inform the police station of the area about the case
irrespective of whether the patient survives or dies and whether it appears to be a
case of suicide or homicide or accident.
(h) If death is apprehended then arrangement for recording dying decleration
should be made.
(i) In case of death, death certificate should mention about the poisoning or
suspected poisoning with recommendation for post-mortem examination. .
WHO recognized Poison Information Centers in India
Poisons Information Centre
National Institute of Occupational Health, Meghani Nagar
Ahmedabad 380 016
Director: Dr A. Dewan
Telephone: +91 79 286 7351
Emergency telephone: +91 79 562 1400
Fax: +91 79 286 6630
Dept of Toxicology
(Incl. Poison Information & Laboratory Services )
Amrita Institute of Medical Sciences & Research
Cochin 682026, South India
Director: Dr V. V. Pillay
Telephone: +91 484 2804852 (O), +91 484 2807055 (R),
9895282388 (Cell 24 hrs)
Fax: +91 484 2802051
Toxicology & IMCU Unit
Government General Hospital
Director: Dr C.Rajendran M.D
Telephone: +91 44 536 3208 or + 91 44 536 3131 ext. 108
Fax: +91 44 538 8521
Web site: http://www.chennaipic.com/
Information also at http://www.whoindia.org/ and go to
Environment health/Poison Prevention/Helpline
National Poisons Information Centre
All India Institute of Medical Sciences , Ansari Nagar
New Delhi 110 029
Telephone: +91 11 6859391
Emergency telephone: +91 11 661123
Fax: +91 11 6859391
Note: The above notes and other teaching material are also available on the departmental website www.forensicindia.com
By: Dr. Imran Sabri, Department of Forensic Medicine, J.N. Medical College, A.M.U. Aligarh.
Forensic toxicology is essentially a specialty area of analytical chemistry. Toxicology is the science of adverse effects of chemicals on living organisms. In general, a toxicologist detects and identifies foreign chemicals in the body, with a particular emphasis upon toxic or hazardous substances. A descriptive toxicologist performs toxicity tests to evaluate the risk that exposure poses to humans. A mechanistic toxicologist attempts to determine how substances exert deleterious effects on living organisms. A regulatory toxicologist judges whether or not a substance has low enough risk to justify making it available to the public.
A toxin is any material exerting a life threatening effect upon a living organism. Poisons are a subgroup of toxins. Toxic materials exist in many forms (gaseous, liquid, solid, animal, mineral, and vegetable), and may be ingested, inhaled, or absorbed through the skin. Poisons generally enter the body in a single massive dose, or accumulate to a massive dose over time. Toxins work in minute quantities or low levels, requiring sensitive analytical instruments for detection. Some toxins have medicinal value, but many produce irreparable damage. Some toxins have antidotes and others do not. Poisons can be combated by prompt treatment, and most organ damage (except for serious CNS injury) may be repairable. Whereas poisons are somewhat easily identifiable by their symptoms, many toxins tend to disguise or mask themselves. Here's a list of the more common poisons and their symptoms:
The true incidence of poisoning in the United States is unknown. Approximately 2 million cases are voluntarily reported to poison control centers each year, and officially, a rather steady figure of about 700 deaths by poisoning is reported each year. Children under age 6 account for the majority of poisonings reported, but adults account for the majority of deaths by poisoning, most of which is intentional rather than accidental. The following tables show a ranking of the most frequently reported poisonings (left) compared to the most frequent deaths by poisoning (right):
Paracelsus (1493-1541) once said "All substances are poisons; there is none which is not a poison. The right dose differentiates a poison and a remedy." Although society wants the toxicologist to categorize all chemicals as either safe or toxic, this is not possible. It is not easy to distinguish toxic from nontoxic substances. A key principle in toxicology is the dose-response relationship. There is a graded dose-response relationship in individuals, and a quantal dose-response relationship in the population. The quantal dose-response is the more important one, used to determine the median lethal dose (LDm) and judge what percentage of the population is affected by a dose increase. Quantal is a term meaning "all or none", and comes closest to a classification of whether something is safe or toxic.
Chemicals are tested for toxicity and the estimation of LDm using at least two (2) animal species by at least two (2) routes of administration. One of these portals or routes of administration is supposed to be the suspected portal for how human beings are exposed. Most animals die within 14 days, and their symptoms are carefully recorded. Subacute exposure is tested for a period of 90 days. Long-term exposure testing takes 6 months to 2 years. Cancer research goes on for the life of the animal, or in the case of the Ames test, to see if reverse mutation occurs to predict carcinogenic effects. Mathematical extrapolation is used to generalize results from animal testing to human risk incidence. A 0.01% risk in the human population represents 25,000 people in a population of 250 million, and to have valid extrapolation at this level, a minimum of 30,000 animals would have to be tested. Humans are generally more vulnerable than animals, so the calculations are inherently conservative.
The toxic effects of substances are not side effects. Side effects are defined as non-deleterious, such as dry mouth, for example. Toxic effects are the undesirable results of a direct effect. They occur in a number of ways, most often produced by a dangerous metabolite of the drug which is activated by an enzyme, light, or oxygen reaction in a process known as biotransformation. Toxic reactions often depend on how metabolites are processed by an individual's body, how proteins build up and bind at effector sites in the body. Some metabolites destroy liver cells, others brain tissue, and still others operate at the DNA level. Toxic reactions are classified as one of three (3) reactions:
pharmacological -- injury to the central nervous system (CNS)
pathological -- injury to the liver
genotoxic -- creation of benign or malignant neoplasms or tumors
If the concentration of toxin doesn't reach a critical level, the effects will usually be reversible. Pharmacological reactions, for example, are of this type. In order to sustain permanent brain damage, dosages must be above a standard critical level. Pathological reactions can be repaired if discovered early enough, but most liver damage occurs over a period of few months to a decade. Genotoxic or carcinogenic effects may take 20-40 years before tumors develop. Most of the time, toxic metabolites are activated by enzymatic transformation, but a few are activated by light. This means that exposure of the skin to sunlight produces a photoallergic reaction or phototoxic reaction within 24 hours. It's important to understand that the target organ of toxicity is not the site where toxin accumulates. Lead poisoning, for example, results in an accumulation of lead in bone marrow, but the toxic effect is the creation of lesions on skin and soft tissue. Carcinogenesis is even more complicated, involving the creation of promotor electrophiles which serve to activate or potentiate the growth of latent tumors given some biological trigger or subsequent environmental attack. Different people, of course, have chemical allergies (as well as food allergies), depending upon the serology of their allergen-antigen history. In such people, toxic reactions take different forms. Other people have what are called idosyncratic reactions, which means they have certain unique genetic triggers. Furthermore, people exposed to multiple toxins can have synergistic reactions, which means that two or more toxins interact at the metabolic level to be greater or less than the effects of the individual toxins.
For certification as a toxicologist, an individual must possess a Ph.D. or doctorate in one of the natural sciences. Undergraduate degrees must also be in these areas (biology or chemistry, usually). Grandfather clauses exist in many states for those lacking the requisite degree level, but who have been working six years or more in the field. Certification is bestowed by the American Board of Forensic Toxicology, and the expert may use the title of "Diplomate" which must be renewed every three years. Board-certified toxicologists will never face difficulties qualifying as an expert witness. State crime laboratories may not have a toxicologist on staff, their functions being performed by a criminalist, a biochemist, a forensic biologist, or other technician. Such personnel would normally possess a Bachelor's or Master's degree. A few states have laws which make toxicological examinations admissible by statute without the necessity for testimony by an expert, the purpose of which is to insulate and protect their crime lab technicians. Other states rely upon their Chief Medical Examiner's office, local hospitals, and forensic pathologists or serologists. Professors are usually not "borrowed" from nearby universities as experts as in the case with forensic serology. Toxicology services vary widely from state-to-state.
There are about 120 poison control centers in the United States, 34 of these designated as regional centers. They are coordinated and served by the FDA's Poisoning Surveillance and Epidemiology Branch. Many toxicologists work for the FDA (Food and Drug Administration) which is responsible for regulating drugs, medical devices, cosmetics, acceptable daily intake (ADI) of food additives, and enforcing the Delany Amendment, which says that no cancer-producing substance should be added to our diet in any amount. Other agencies where toxicologists are often found include the EPA (Environmental Protection Agency) which is responsible for regulation of pesticides, toxic chemicals, hazardous wastes, and toxic pollutants in water and air. OSHA (Occupational Safety and Health Administration) also uses toxicologists to determine if chemicals in workplace air is below a threshold limit value (TLV). The Consumer Products Safety Commission regulates all products, typically those sold for use in homes, schools, or recreation, not regulated by the FDA or EPA.
A forensic toxicologist is normally presented with preserved samples of body fluids, stomach contents, and organ parts. They will have access to the coroner's report which should contain information on various signs and symptoms as well as other postmortem data. The toxicologist needs a through knowledge of how the body alters or metabolizes drugs because few substances leave the body in the same state as they entered. The substances they work with are often derivatives, which is a term meaning a chemical compound which is prepared from a pure compound in order to be more easily detected by the analytical techniques used. They also divide specimens up into acidic and basic fractions for drug extraction from tissue or fluid. Almost all drugs are either acids or bases (on a pH scale from 0 to 14 with closer to 0 being acids and closer to 14 being bases). Acid drugs are easily extracted with a pH solution of less than 7; base drugs are easily extracted with a pH solution of greater than 7. As an example, most of the barbiturate drugs are acid-soluble; most of the amphetamine drugs are base-soluble.
After preliminary acid-base procedures are carried out, and the tissue or fluid sample is now a drug sample, examination continues in two steps: (1) screening tests, and (2) confirmation testing. Screening tests allow the processing of many specimens for a wide range of toxins in a short time. Any positive indications from the screening tests must be verified with a confirmation test. The following are some standard laboratory tests for toxin detection:
Physical tests -- boiling point, melting point, density, and refractive index
Crystal tests -- treatment with a chemical reagent to produce crystals
Chemical spot tests -- treatment with a chemical reagent to produce color changes
Chromatography (thin-layer or gas) -- used to separate components of a mixture
Mass spectrometry -- this is a combination of gas chromatography/mass spectrometry which is generally accepted as the confirmation test of choice. Each toxin has a known mass spectra, or "fingerprint", which is infallible proof of its presence at the chemical level
Ordinarily, the toxicologist is not required to render an opinion of whether the toxin levels in the body were enough to cause death. A few toxicologists may do so, but they must have had special training in physiology, and this is usually the province of the forensic pathologist, in any event. Often, the defense will call their own medical experts to dispute a cause of death claim. Physicians are the only ones qualified to render opinions on the physiological effects of toxins, and forensic law allows them to provide their testimony in the form of hypotheticals, even though they do not have personal knowledge of the case. Low-level toxin cases usually become a real battle of the experts.
Drug overdoses and alcoholic poisonings will provide most of the work for toxicologists, hence a couple of allied subfields may be drawn upon: (1) a field inhabited by what are called Drug Recognition Experts (DRE); and (2) alcohol intoxication measurement (a subject talked about in a previous lecture). Both are sought-after areas of police training. Another related subfield involves carbon monoxide poisoning, which may involve an automobile engineer or fire safety specialist.
The Drug Recognition Expertise evolved out of experiments in California with the LAPD during the 1970s in which police officers were trained to identify and recognize certain types of drugs based upon the impairments and physiological symptoms. The examination that such specially trained police officers conduct goes beyond normal Nystagmus testing and more closely resembles the taking of vital signs by a nurse or paramedic, combined with structured interviewing and observation. DRE's opinions are limited by law to identification of a class or family of drugs, not to a specific drug. Standardized checklists and computer programs exist to make this a growing area of modern drug testing.
The traditional field testing methods run the gambit of color to crystalline tests, and consist of a variety of names, the controversial Nalline test being the most well-known, which presumably indicates recent use of narcotics. Here's a list of some common drugs and specific tests for them:
Opium is a true narcotic, providing an euphoric escape from reality. It is derived from the milky secretions of the poppy bulb before flowering. In raw form, it turns dark brown and stays moist. The most common type of opiates are:
Morphine -- a natural alkaloid that makes up 10% of poppy juice
Paregoric -- morphine mixed with an alcohol solution
Codeine -- alcoholized poppy juice crystals
Heroin -- poppy juice treated with hydrochloric acid; 3x more powerful than morphine
Demerol and Methadone -- synthetic opium-like substances made in laboratories
Marijuana is technically a hallucinogen but has been thrown in with narcotics since Reyna v. State 1968. It tends to make a person lethargic rather than euphoric (an effect like alcohol but without the aggression). It's active ingredient is THC (tetrahydrocannabinol) which is contained mostly in the flower tops and to a lesser extent in stems and seeds. One particular species, Cannabis Sativa, as opposed to other species, e.g. Cannabis Indica, Cannabis Ruderalis, tends to contain more THC (Delta-9-THC) as the main cannabinoid, than the other species, if "species" is the right word since Small & Cronquist's (1976) study found only one single species with two subspecies (Sativa & Indica), each divisible into a cultivated and wild variety. Cannibis Indica has a significant amount of THC as well, along with several other cannabinoids. It should be noted that some experts classify Indica as a subspecies of Sativa, thereby frequently missing an accurate description of Indica's chemical profile. The THC content is heavily affected by the sex of the plant, with female plants generating substantially more resin than their male conterparts. Toward this end, during plant growth, males are generally removed before pollination occurs. The average marijuana cigarette contains only 1% THC while hashish (made from ground flower tops) is 10% THC. Other hallucinogens include:
Peyote -- green, mushroom-like buttons on cactus plants
Psilocybin -- naturally-growing mushrooms
Mescaline -- the active ingredient in peyote, synthetically produced
LSD -- 400 times stronger than mescaline
PCP -- animal tranquillizer
Nutmeg and Jimson Weed -- other naturally-growing plants
Cocaine is technically a stimulant, but has been thrown in with narcotics since too many cases to remember. It's a natural alkaloid found in coca leaves (C17 H22 CLNO4). For making what is called freebase or crack, it's melting point needs to be lowered, and this is done by releasing the hydrochloride in it (HCL) through mixing it with a sodium substance like baking soda, adding water, letting it cook slowly, and then letting it cool off. The crystal residue or pellets are called "crack" which is a widely abused drug. Other stimulants range from the least powerful (benzedrine and dexedrine) to the most powerful (methamphetamine).
Barbiturates are known by the color of their tablets: Nembutal (yellow jackets); Seconal (reds); Tuinal (Christmas trees); and Amytal (blues). Steroids are another group or family of drugs, and the anabolic ones (that promote muscle growth) exist in about 80 different varieties.
So-called designer or "rave" drugs are hallucinogens, mostly, which have been chemically altered in some way to as not to be placed on the controlled substances list. However, under emergency measures, the DEA can put anything on the list they want. Such drugs are: MDMA, XTC, Ice, and Nexus. Here's the controlled substances list and some sample penalties for trafficking:
Quite a few interesting defenses exist to a drug charge. With marijuana, for example, one could raise the "species defense" and then the plant would have to be proved to be Cannibus Sativa. With steroids, one could raise the "roid rage" defense, that their behavior was out of control. A basic defense is that the person was not trying to feel good, but feel better, a "medical necessity" defense. It's unconstitutional to make the status of being an addict a crime in itself (Robinson v. California 1962).
Drug charges can also be challenged on scientific grounds, as follows:
MegaLinks in Criminal Justice Source: http://faculty.ncwc.edu
Forensic Medicine Source:
Clinical Guidelines for the Determination of Death - New York State Dept. of Health (US)
Forensic Pathology, images - WebPath
Forensic Science Service - Birmingham (UK)
Department of Forensic Medicine - Victorian Inst., Monash University (AU).
Zeno's Forensic Site [Z Geradts] - (NL).
Reddy's Forensic Home Page [RP Chamakura]
Forensic Toxicology Page [A Barbour] including the World Wide Web Virtual Library: Forensic Toxicology
Forensic Toxicology Page [A Aggrawal]
The Forensic Science Society - (UK)
A Beginner's Primer on the Investigation of Forensic Science [K Kruglick] - Scientific Testimony (journal)
Osteo Interactive - Univ of Utah (US)
Links to some Forensic Science Resources
Forensic Psychiatry & Medicine [HJ Bursztajn]
Forensic Anthropolgy - Univ of Utah (US)
'The Killer's Trail' - PBS/NOVA
Bite Marks as Evidence to Convict [K Ramsland] - The Crime Library
Victimology [W Petherick] - Crime Library
Victim and Victimology Resources [links ; CL Dreveskracht]
On the History of fingerprints [K Skopitz]
How is DNA Fingerprinting Done? [Brinton and Lieberman] - Univ of Washington
A Mistaken DNA Identification? [AA Moenssens]
DNA Testing: An Introduction For Non-Scientists [DE Riley] - Scientific Testimony
Forensic DNA Typing [JM Butler; sample chapter from the book]
Mitochondrial DNA and Forensics - Mitotyping Tech., LLC
The Innocence Project - (US)
About Paternity testing at the Victorian Institute of Forensic Medicine
About CODIS: Combined DNA Index System - FBI (US)
About Restriction Fragment Length Polymorphisms [J Kimball]
A summary of the technology behind 'Brain Fingerprinting' [LA Farwell; May 2000] - Forensic Evidence
Accidental Fire or Arson? [Cafe and Stern] The Science and "Art" of Fire Investigation , and some Useful Physical Constants for the Fire Investigator [Cafe] -T.C. Forensic (AU)
Microbial Forensics - American Acad. of Microbiology
Forensic Entomology - Natural History Museum (UK)
About Firearms Injuries [EC Klatt]
Crime Scene Investigation - (US)
Crime Library - (US)
'Visible Proofs' - Exhibition at NLM/NIH (US)
Some Sudden Death scenarios [registration required] - Liverpool Hospital/Trauma (AU)
Blood stain pattern analysis with computers [AL Carter] - (CA)
Visible Proofs: Forensic Views of the Body - Exhibition at NLM (US)
Reconstructions based on Unidentified Human Remains - Michigan State Police (US)
The Vidocq Society - Philadelphia (US)
Medical Legal Art - (US)
A guide to Crime and Punishment - About.Com (US)
Crime Magazine - an encyclopedia of crime
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