Classification Of Corrosives According To Forensic Medicine and Toxicology and Explanation of Mineral Acids and Caustic Alkalis

1. Corrosives
By Dr. Salman Ahmed

2. Classification
Mineral Acids
Sulphuric Acid
Nitric Acid
Hydrochloric Acid
Organic Acids
Oxalic Acid
Carbolic Acid
Acetic Acid
Salicyclic Acid
Vegetable Acid
Hydrocyanic Acid

3. Mineral Acids and Caustic Alkalis
 In Dilute Solutions,they act as irritants
 Their action is mainly a local one on the tissues of the
alimentary tract and to some extent on the respiratory tract
 Their action is characterized by (1)extraction of water from
tissues (2)coagulation of cellular proteins(3)conversion of
haemoglobin into haematin

4. General Signs & Symptoms
 Onset is Immediate
 Soon After ingestion, there is burning sensation in the mouth,
throat, esophagus, stomach and abdomen, followed by
intense thirst, difficulty in swallowing, continuous retching and
vomiting of shredded blood stained material
 The Tongue is swollen or shriveled according to the nature of
the corroding agent
 With The ingestion of corrosive acids, the bowels tend to be
constipated and urine scanty but with alkalis, there may be
tenesmus and frequency of stools with blood and mucus

5. General Signs & Symptoms
 Dyspnea is often present from edema of the glottis
 Collapse from shock sets in ,with cold clammy skin, pale
anxious face, sunken eyes, dilated pupils, rapid feeble pulse
and signing respirations
 Consciousness is usually retained until near the end and death
may result from primary shock, suffocation due to edema of
the glottis or perforation of the stomach

6. Treatment
 Stomach tube and emetics are contraindicated
 However, a soft stomach tube or Levine tube can be passed
with care within about an hour of the ingestion of poison to
prevent serious caustic burns of the stomach wall followed by
ulceration, contraction and even stricture
 If an acid has been taken, alkaline carbonates are
contraindicated.Weak alkalis and plenty of water or
neutralizing agents such as milk and egg albumin should be
given
 In case of an alkali,weak acid such as vinegar will neutralize its
effects
 Morphine by injection is necessary to relieve pain,ice to suck to
relieve thirst,intravenous fluids to combat fluid lossand
corticosteroids for shock and to prevent esophegal stricture

7. Postmortem Appearance
 Externally, Lips may be burnt and trickle marks may be found
running from the mouth to the chin, neck, and chest
 Internally, they vary in extent from localized patches to
extensive areas, particularly in stomach
 Perforation in stomach is common with sulphuric acid
 Irritation of the respiratory tract is found in case of volatile
poisons eg Nitric Acid, Hydrochloric acid

8. Medicolegal Aspects
 Attempted Suicide with corrosives is not seen
 Corrosives are rarely used for Homicide owing to their painful
action
 They are sometimes thrown on the face out of jealousy or in
fits of rage, This is known as Vitriolage.They cause severe
injury or even death from accidental spilling

9. Vitriolage
 This means throwing of any corrosive on a person with malicious
intent
 These fluids are usually thrown on the face with the object of
destroying vision or causing facial disfigurement and this results in
grievous hurt
 Sulphuric acid(oil of vitriol) is most commonly employed for this
purpose and hence it is called vitriolage
 Sulphuric Acid produces severe chemical Burns
 They are characterized by discoloration, staining of skin and
clothing(brown or black in Sulphuric Acid and Yellow In Nitric
Acid),trickle marks, absence of vesications and red lines of
demarcation and the presence of the chemical substance in the
stains

10. Treatment
 Immediate treatment consists in washing away the corrosive
acid with large amount of water and soap or dilute solution of
sodium or potassium bicarbonate
 Later, a thick paste of magnesium oxide is applied
 The raw surface may afterwards be covered with antibiotic
ointment
 When the eyes are involved, they should be washed at once
with large amount of water followed by irrigation with 1%
solution of sodium bicarbonate
 A Few drops of olive oil are then instilled into the eyes
 Eye drops containing antibiotics and steroids are helpful

11. Shahnaz Bibi, 35, poses for a photograph in Lahore,
Pakistan, Sunday, Oct. 26, 2008. Ten years ago Shahnaz
was burned with acid by a relative due to a familial
dispute. She has never undergone plastic surgery

12. THANK YOU