Forensic Toxicology KJC unit-1.pptx Introduction to Poison

Forensic Toxicology
By: Nandini Katare

Syllabus
 Unit 1: Corrosives and Irritants
Classification of poisons based on mode of action; Corrosives: action, signs and symptoms,
forensic significance; acids: mineral and organic acids; Alkalis: caustics and salts; Irritants:
action, signs and symptoms, forensic significance; Inorganic irritants: arsenic, mercury, lead,
phosphorus; Organic irritants- Plant irritants: abrus, castor, calotropis, marking nut; Animal
irritants: snakes, snake venom, scorpion, wasps, bees, cantharides; Mechanical irritants.
 Unit 2: Systemic poisons
Neurotics: action, signs and symptoms, forensic significance; Cerebral poisons: inebriants:
ethanol, methanol, chloral hydrate; somniferants: opium, opiates, opioids; Deliriants: cocaine,
dhatura, cannabis; Barbiturates; Tranquilizers; Anti-histamines; Spinal poisons: strychnine;
Peripheral poisons: pesticides (Organophosphates, Organochlorines, Carbamates, pyrethroids)
Cardiacs: action, signs and symptoms, forensic significance; Oleander, digitalis, rodenticides
(phosphides)
Asphyxiants: action, signs and symptoms, forensic significance; Asphyxiating gases: CO, CO2,
H2S, nerve gas.

Unit: 3: Extraction methods
Systematic extraction, isolation, identification, estimation from viscera, blood and urine by
distillation, acid digestion, wet digestion, ammonium sulphate method; Modified stas-otto method of
following poisons: Common volatile poisons, plant poisons, insecticides, metal poisons, pesticides;
Dry ashing; miscellaneous extraction techniques; Automated extraction system.
Unit: 4: Analysis of Toxicological Samples
Classification of poisons based on chemical nature; collection and preservation of viscera, blood and
urine; processing of viscera in lab; Spot tests; Instrumental techniques: Thin Layer Chromatography,
High Performance Liquid Chromatography, Gas Chromatography, Spectroscopy, hyphenated
techniques, role of forensic toxicologist; Format of report writing; Section 293 CrPC; Expert
testimony.
Unit 5: Analysis of Narcotic Drugs and Psychotropic Substances
Role of forensic chemist, evidence handling techniques, analysis of NDPS evidence as prescribed by
WHO Manual, DFSS manual, spot tests, microcrystal tests, extraction methods; Analysis of cocaine,
cannabis, barbiturates, benzodiazepines, amphetamines, opiates and hallucinogens (LSD, psilocybin
and mescaline) using TLC, UV-Vis spectrophotometry, IR spectrophotometry, GC, HPLC, MS, GC-MS,
NMR and XRD; Clandestine laboratory investigation and designer drugs, NDPS act. Importance of hair,,
nail and body fluids in drug analysis.

Introduction- Toxicology
 The word “Toxicology” is derived from the Greek word “toxicon”
which was used as a poisonous substance in arrowheads.
 Conventionally, the toxicology may be defined as the science
representing the character, source, knowledge, lethal dose, fatal
effect, analysis of poisons and their curative measures.
 More precisely, Toxicology can be said as the study of antagonistic
effects of chemical or physical agents on living organisms.

Definition- Forensic Toxicology
 Forensic toxicology is a specialized branch of forensic
science that deals with the study of toxic substances and
their effects on the human body in the context of legal
investigations.
 This field plays a crucial role in understanding the
presence of drugs, poisons, and other toxic chemicals in
biological specimens and their potential contribution to
criminal activities, accidents, or unexplained deaths.

Key Components of Forensic Toxicology:
 Identification of Toxic Substances
 Quantification of Substances
 Interpretation of Findings
 Postmortem Toxicology
 Drug Facilitated Crimes
 Workplace and Environmental Exposure
 Expert Testimony:

Poison
 Poison is any substance (solid, liquid, gas) which if assimilated in the
living body or brought into contact with any part thereof, will lead to
deterioration of health or may eventually lead to death by its
constitutional or local effects.
 Every agent may be harmful if acting on an organism at a high enough
dose.
 Poison may also be defined, as a material which when administered,
inhaled or ingested is capable of acting deadly on the human body. Thus
almost anything is a poison.

 There is very minute difference between medicines or
poison, a medicine in a toxic dose is a poison and a poison in
a small dose may be a medicine.
 According to law the key distinction between a medicine
and poison is the intent with which it is given to a person.
 Therefore, if the substance is administered with the
intention to save a life, it is a medicine but it acts as a poison
if it is given with the intent to cause harm to the body.

Classification of poison
 Classification of poisons can be done according to
 A) Mode of action
 B) Chemical nature
 Both classifications have their own importance in forensic
investigation. Mode of action helps in determining the type of
poison and on the other hand chemical nature of poison helps in
analyzing it.

Classification of Poison on the mode of
Action:
 Poisons can be classified into three major categories based on
their mode of action:
 1. Corrosives
 2. Irritants
 3. Systemic

Forensic Toxicology KJC unit-1.pptx Introduction to Poison

1. Corrosive Poison:
 A corrosive poison is simply a highly active
irritant and not only produces inflammation
but also actual ulceration of the tissues.
 Basically a corrosive poison fixes, destroy and
erodes the surface with which it comes in
contact i.e. they produces local action.

 They act by extracting water from the tissues and
coagulate cellular proteins.
 This group consists of strong acids and strong alkalis.
 These include mineral acids, such as sulphuric acid,
nitric acid, hydrochloric acid; organic acids, such as
oxalic acid, carbolic acid, acetic acid, salicylic acid;
concentrated alkalis such as, caustic soda, carbonates,
ammonium, sodium and potassium.

Fig showing action of acid on the dermal
tissue

2. Irritants
 Irritant poisons causes pain in abdomen, vomiting and
purging. In post-mortem appearance they are usually
evident to the naked eye and shows redness or ulceration
of the gastrointestinal tract.
 This group is further divided into; inorganic, organic, and
mechanical substances. Corrosives in dilute solutions act as
irritants.

Difference between Irritants and
Corrosives
 Irritant Poison causes reversible damage to skin or
other organ system, whereas a corrosive agent
produces irreversible damage, namely, visible
necrosis into integumentary layers, following
application of a substance for up to 4 hours.
 Corrosive reactions can cause coagulation or
liquefaction necrosis.

Types of Irritant Poison
 Inorganic Irritant Poison:
 The inorganic subgroup consists
of non-metallic and metallic
poisons.
 Examples of nonmetallic poisons
are phosphorous, chlorine,
bromine and iodine etc.
 The metallic poisons include
arsenic, antimony, mercury, lead,
copper, thallium, zinc,
manganese, barium and
radioactive substances.
 Organic irritant Poison:
 This group of poisons
comprises of animal and plant
poisons.
 Examples of plant poison are
abrus precatorius, castor,
marking nut, ergot, calotropis
etc.
 The animal poisons include
snakes, insects, cantharides,
spider etc.

Effects of Irritant Poison on Skin

Neurotics
 Neurotics, also known as psychoactive substances, significantly impact
the nervous system, leading to alterations in mood, perception, and
behavior.
 These substances specifically target and damage the central nervous
system (CNS), peripheral nervous system (PNS), or both, leading to a
wide range of neurological effects.

Mechanisms of Action:
• Depressants: Neurotics like alcohol, benzodiazepines, and barbiturates depress
the central nervous system, leading to reduced neural activity. This can result in
sedation, relaxation, and impaired cognitive and motor functions.
• Stimulants: Substances like cocaine, amphetamines, and caffeine increase
neural activity, leading to heightened alertness, euphoria, and increased energy.
• Hallucinogens: Drugs such as LSD, psilocybin, and PCP alter perception,
cognition, and mood, often inducing hallucinations.
• Opioids: Including opium, heroin, and prescription painkillers, opioids act on
specific receptors in the brain and spinal cord, relieving pain and inducing a sense

Signs and Symptoms:
• Depressants:
• Slurred speech.
• Impaired coordination.
• Sedation or drowsiness.
• Respiratory depression.
• Stimulants:
• Increased heart rate.
• Agitation.
• Elevated blood pressure.
• Insomnia.

• Hallucinogens:
• Altered perception of reality.
• Hallucinations.
• Distorted sense of time.
• Changes in mood.
• Opioids:
• Euphoria.
• Analgesic (pain relief).
• Constricted pupils.
• Respiratory depression.

Forensic Significance:
• Toxicological Analysis: Post-mortem toxicological analysis of blood, urine,
or tissues helps identify the presence and concentration of neurotics.
• Cause of Death Determination: Determining whether the use of neurotics
directly contributed to or caused the individual's death.
• Impairment in Legal Cases: Assessing the role of neurotics in criminal
cases, especially those involving impaired driving or violent behavior.
• Differentiation from Natural Causes: Confirming whether observed
symptoms are due to the effects of neurotics rather than natural medical
conditions.

Action:
 Corrosives are substances that can cause damage to living
tissues and materials by chemical action. They typically act by
breaking down and destroying the molecular structure of
tissues.
 The severity of the damage depends on factors such as the
concentration of the corrosive substance, the duration of
contact, and the specific properties of the corrosive.

Signs and Symptoms
 Skin Exposure: Redness, blistering, and burns.
 Eye Exposure: Redness, pain, swelling, and
potentially irreversible damage to the cornea.
 Inhalation: Respiratory distress, coughing, and
damage to the respiratory tract.
 Ingestion: Burning sensations in the mouth,
throat, and stomach, along with nausea,
vomiting, and abdominal pain.

Acids: Mineral Acids
 Hydrochloric Acid (HCl): Found in stomach acid;
exposure can lead to burns and corrosion.
 Sulfuric Acid (H2SO4): Highly corrosive; can cause
severe burns and tissue destruction.
 Nitric Acid (HNO3): Strong oxidizing agent; corrosive
to tissues and can cause respiratory distress.
Fig. Showing Acid burns

Organic Acid
 Acetic Acid (CH3COOH): Found in vinegar; can cause irritation and
burns.
 Formic Acid (HCOOH): Found in ant venom; exposure can lead to
burns and respiratory distress.

Alkalis
 Caustics:
 Sodium Hydroxide (NaOH): Highly corrosive; causes severe
burns and tissue destruction.
 Potassium Hydroxide (KOH): Similar corrosive effects to
sodium hydroxide.
 Salts:
 Alkali salts can include compounds like sodium carbonate
(Na2CO3) and potassium chloride (KCl).
Fig. Showing caustic Soda
burns

Signs and Symptoms:
 Similar to corrosives; alkalis tend to penetrate tissues
deeply, causing extensive damage.
 Ingestion may result in abdominal pain, vomiting, and
potential perforation of the digestive tract.

 Identification of the corrosive substance involved is crucial for forensic
investigations specially in Vitriolage cases.
 Analysis of the victim's clothing, personal items, and the scene can
provide valuable evidence and Autopsy findings may reveal the extent
of internal damage caused by the corrosive substance.

Inorganic Irritants:
1. Arsenic
 Arsenic is a heavy metal that can enter the body through ingestion,
inhalation, or skin contact.
 It interferes with cellular processes, leading to toxicity.

Forms of Arsenic Poisoning
Acute Inorganic Arsenic Poisoning
Chronic Inorganic Arsenic Poisoning
Arsine Gas Poisoning

Signs and Symptoms:
 Gastrointestinal symptoms (vomiting, abdominal pain,
diarrhoea).
 Neurological symptoms (headache, confusion).
 Chronic exposure may lead to skin and increased risk
of cancer.

Skin changes and appearance of Aldrich Mees
lines on Nails due to chronic arsenic poisoning

 Detection of arsenic in bodily fluids, tissues, and hair is crucial for
forensic analysis.
 Historical cases have involved arsenic poisoning for homicidal
purposes.

2. Mercury
 Mercury can exist in different forms (elemental, inorganic,
and organic) and affects various organs.
 Inorganic mercury can cause renal and gastrointestinal
damage

Signs and Symptoms:
 Neurological symptoms (tremors, irritability).
 Gastrointestinal symptoms (nausea, vomiting).
 Renal damage.
Forensic Significance:
 Detection of mercury in tissues and bodily fluids is important.
 Occupational exposures, environmental sources, or intentional
poisoning may be considered (Mimimata Disaster).

3. Lead
 Lead primarily affects the nervous system and can lead to systemic
toxicity.

Forms of Lead(Pb)
Compound Common name Feature

Types of Pb Poisoning
1. Acute
2. Chronic

Forensic Significance:
 Lead exposure is often associated with occupational or
environmental sources.
 Detection of lead in blood, bones, and tissues is important for
forensic analysis.

4. Phosphorus
 White phosphorus is highly toxic and can cause severe burns.

Cont…
White phosphorus burns

Fig. Showing Match factory worker at the end of 19th century suffering from phossy
jaw with pathological fracture of the mandible and fistula formation

Organic Irritant Poison:
Plants

Marking Nut or Semecarpus
Anacardium

Kannada Geru
Malayalam
Alakkucheru Cherkuru Cheru Cheru
maram Perkuru Sambiri Temprakku T
henkotta

Fatal Dose- 5 to 10 gm
Fatal Period- 12-24 hrs

Treatment
 If Ingested:
 Gastric Lavage
 Demulcent Drinks
 If applied Externally
 Wash with lukewarm water containing
antiseptic

Post-mortem Appearance
Blisters seen in Mouth, throat
and Stomach which are
congested and inflamed.

Ricinus Communis
Malyalam-Aavanakku
Kannada-Oudla

Ricinus Communis (Castor, Arandi)

Uses
• Oils
• Candles
• Cosmetics, Soaps
• Lubricants in jets
• Purgative

Typical Umbrella Used in Homicide

Abrus Precatorius
Kannada-Gulugunji
Malayalam-Chuvannakunni Gunj Kakani
Kunni Kunnikuru

Calotropis
Kannada: bili aekka, bili aekkada gida
• Malayalam: erikku, erukku

Slide Title
Product A
 Feature 1
 Feature 2
 Feature 3
Product B
 Feature 1
 Feature 2
 Feature 3

Organic Irritant -Animal Poison

Venom
 Venom is an animal poison,
contains different types of
antigens (proteins enzymes like
protease, phosphodiesterases,
hyaluronidases, phospholipase) .
 Of the 2500-3000 species of snakes
distributed world-wide, about 500 are
poisonous to Humans.

Snakes
 Snakes belong to the class Reptilia, order squamata, and sub-order
Serpentes.Snakes are nocturnal reptiles & undergo
hybridization.
 The three main families of poisonous snakes exists are the Elapidae
(cobras), the Viperidae (vipers) and the Crotalidae (pit vipers).
 The elapids cover around half the world’s species of venomous
snakes and contain the Cobras and the Mambas.

Classifications of snakes
 According to the dominant venom:
 Snake venom: Mixture of specific toxins
(peptides& small proteins as hemotoxin,
neurotoxin, cardio toxin, …) and spreading
factors (enzymes as hyalourindase,
phospholipase A, …)
1. Hemotoxic: vipers
2. Neurotoxic : cobra
3. Myotoxic : Sea snakes

 Neurotoxic venom:
 Dominant in cobra venom
 50-75% have low MW so, dialyzable
 Act mainly on neuromuscular junctions -> weakness
 dangerous when affect respiratory muscles ->
respiratory failure.
 Hemotoxic venom :
 Dominant in viper snake venom
 Have high MW so, not dialyzable
 Mainly composed of hemolysin, thromboplastin,
cardiotoxin
 Can cause: hemolysis, destruction of vascular
endothelium, cerebral and intestinal hemorrhage,
hypotension & shock, and tissue necrosis.

 Neurotoxic Venom:
 Start 15-45 minutes after biting
 Local : fang mark (2 punctures), pain, redness, hotness, swelling,& may
wet gangrene (generally less prominent than with hemotoxic venom)
 Systemic : 1 st sign is ptosis & numbness in lips & tongue – giddiness –
heaviness in bitted limb – salivation & vomiting – blurred vision –
dysarthria – dysphagia – bradypnea – convulsions – coma & death due to
resparatory failure

 Hemotoxic Venom:
 Local : prominent and include: fang marks, severe pain, redness,
ecchymosis, hotness, edema and swelling of affected limb & dry
gangrene
 Systemic : nausea, vomiting – hypotension with rapid weak pulse –
bleeding from mucous membranes – acute renal failure due to
hemoglobinuria – coma and death due to circulatory collapse

Clinical Manifestations
 The manifestations & severity of the case are depended on:
1. Amount of venom injected
2. Species of snake & nature of venom
3. Site of bite
4. Time of bite
5. Condition of fangs
6. Pathogens in mouth of snake
7. Death may occur immediately due to neurogenic shock

Composition of Snake Venom
 The cobra venom in Neurotoxic and produces muscular paralysis involving firstly the
muscles of the mouth, throat and lastly muscles of respiration, seats the action of venom
being upon the motor nerve cells, the action resembling curare. It consists of:
 (i) Neurotoxin
 (ii) Cholinesterase
 (iii) Proteases
 (iv) Phosphatidases
 (v) Hyaluronidase
 (vi) Ribonuclease
 (vii) Thromboplastin
 (viii) Fibrinolysin
 (ix) Proteolysin
 (x) Cardiotoxin

 The viperine venom is predominantly haemolytic and hemotoxic. It causes
lysis of red cells and other tissue cells and coagulation disorders bringing
about coagulation of the blood and clotting of the pulmonary arteries.
 There will be haemorrhage from the site of bite, associated with the necrosis
of renal tubules, convulsions from intra-cerebral haemorrhage. It consists of:
 (i) Proteases (ii) Hyaluronidase (iii) Haemorrhagin (iv) Haemolysin (v)
Leucolysin (vi) Lecithinase (vii) Cytolysin (viii) Thromboplastin (ix)
Phospholipase- A (x) Proteinases.

 Fatal doses of various bites are:
 (i) Dried cobra venom : 12 - 15 mg
 (ii) Dried viper venom : 15 - 20 mg
 (iii) Dried krait venom : 5 - 6 mg
 (iv) Dried Saw Scaled viper venom : 8 mg
 Fatal Period:
 The death may occur instantaneously from neurogenic shock resulting from
fright
 otherwise the fatal period is:
 (i) In colubrine bite : ½ - 24 hours
 (ii) In viperine bite : 2 - 4 days

Management of toxicity
 Reassurance of patient is important
 First step is to examine the site of bite and decide if the bite is poisonous or not to avoid
unnecessary use of polyantivenom as it is risky and expensive
 Immobilize the affected limb
 Stop venom absorption as possible using tourniquet proximal to bite (just enough to obstruct
lymph drainage not venous drainage) and make 2 small incisions over fang marks, and suction
 Don’t use ice fomentations to avoid gangrene or give aspirin to avoid bleeding

 Supportive Treatment:
1. Open IV line and correct fluid, electrolytes
and acid-base balances
2. In all cases of snake bite either poisonous or
nonpoisonous, we have to give broad spectrum
antibiotics and anti-tetanic serum owing to
pathogens found in snake mouth

 Specific treatment :
 Antivenoms can be classified into:
1. Monovalent (when they are effective against a given species' venom)
2. Polyvalent (when they are effective against a range of species, or several different species at
the same time).
 Dose : depends on severity of bite not age or body size so the dose for a pediatric is equal to an
adult dose:
- mild give 3-5 vials
- moderate give 5-10 vials
- severe cases give 10 vials & maintain with more vials according to situation

 Antivenoms are purified by several processes but will still contain other serum proteins that can
act as antigens .
 Some individuals may react to the antivenom with an immediate hypersensitivity reaction (
anaphylaxis ) or a delayed hypersensitivity ( serum sickness ) reaction and antivenom should,
therefore, be used with caution.
 Despite this caution, antivenom is typically the sole effective treatment for a life-threatening
condition
 The side effects are manageable, and antivenom should be given as rapidly as the side effects
can be managed.

SCORPIONS
 Scorpions are poisonous arthropods
that have a fleshy segment body with
four pair of legs, a pair of claws and a
tail.
 The posterior segment is long and
bulbous and contains the venom gland
and a hollow sting at the end of the
tail in its last joint.

 The sting communicates with the venom gland by means of a duct
and it then inject venom in the injury produced by it.
 The adult scorpion are 2 - 20 cm long and big, black coloured are
more dangerous than the small, brown ones.
 The scorpion’s bites are mainly accidental as they live in cracks and
holes in the houses.

 The main toxins include phospholipase, acetylcholinesterase,
hyaluronidase, serotonin, and neurotoxins.
 The venom of Buthus species of India contains
Phospholipase- A, which causes gastrointestinal and
pulmonary haemorrhages, and disseminated intravascular
coagulation.
 Scorpion venom is clear and colourless toxalbumin. Generally
more toxic, more variability of specific toxins & more
multiplicity of antigens than snake venom
Scorpion Venom

 Consists of amino acids, peptides & small proteins (mainly
neurotoxin , nephrotoxin, cardiotoxin, hemolytic toxin,
histamine, serotonin, anti-ACh-esterase) & enzymes as
phospholipases, hyaluronidases, phosphodiesterase.
 Injectable LD: up to 50 μ g
 Human have unique variable susceptibility to scorpion venom

Toxic Mechanism of Scorpion Venom
 Neurotoxin:
 Block voltage-gated Na+ & K+ channels….prolonged action potential &
excessive release of catecholamine…..adrenergic manifestations
 The long-chain polypeptide neurotoxin causes stabilization of voltage-
dependent sodium channels in the open position, leading to continuous,
prolonged, repetitive firing of the somatic, sympathetic, and
parasympathetic neurons.
 This repetitive firing results in autonomic and neuromuscular over-excitation
symptoms, and it prevents normal nerve impulse transmissions

 the short polypeptide neurotoxin blocks the potassium channels.
 Anti-cholinesterase….. accumulation of Ach…..cholinergic manifestations.
 Somatic and cranial nerve hyperactivity results from neuromuscular overstimulation.
 Serotonin may be found in scorpion venom and is thought to contribute to the pain associated
with scorpion envenomation.

Factors Affecting Severity of Scorpion
Sting
 Age & body size of the victim
 Species & size of scorpion
 The amount of venom injected
 Site & number of stings
 Individual susceptibility to venom
A smaller child, a lower body weight, and a larger ratio of venom to body
weight lead to a more severe reaction

Signs and Symptoms
 Local: severe intense pain, edema, numbness & tenderness.
 CVS: sinus arrhythmias, hypertension, pulmonary edema, ischemic changes in ECG, complications
are more in children with increased LDH & CPK.
 CNS : agitation, paresthesia ,irritability & (restlessness, severe involuntary shaking &jerking
extremity due to somatic skeletal neuromuscular dysfunction). cerebral edema -> convulsions &
coma
 Others: nausea & vomiting, hypothermia , blurring of vision, tongue fasciculation slurred speech,
diaphoresis, tearing

Management of Scorpion Sting
 First aid: like snake but, it is mandatory to control local pain
(use local anaesthesia) to make the patient calm which is
very important procedure in management
 Specific treatment: use polyantivenom as in snake
 Supportive treatment: support CV functions to avoid
complications
- Symptomatic treatment

 Don't attempt to cut the wound and suck out the poison. This can cause infection or transfer
the venom into the bloodstream of the person attempting to remove the poison.
 Scorpions cannot usually deliver enough venom to kill a healthy adult.
 While venom toxicity varies among species, some scorpions contain very powerful neurotoxins,
which, ounce for ounce, are more toxic to humans than the venom of cobras.
 However, scorpions inject relatively small amounts of venom (compared to snakes), so the
overall dose of toxins per sting is survivable.

CANTHARIDES (SPANISH FLY)
 The beetle Cantharis vesicatoria, known as ‘Spanish fly’ contains
a vesicant, ‘cantharidin’.
 Contact of either with the live or the dried beetle with the skin
results in immediate burning with vesication.
 Besides this, other beetles causing similar representations
includes Epicauta cinerea (blister beetle) and members of genus
Paederus.

 Cantharidin is a powerful vesicant and may be
administered in the form of powdered beetles or the
tincture.

 Fatal Dose
 Cantharidin is a nephrotoxic or kidney poison
and is readily absorbed from all surfaces
including the skin.
 10 mg. of Cantharidin or 1.5 gm of powder
cantharides is found to be a fatal dose.

 While snakebites are more common in tropical countries such as India, anaphylactic
reaction to hymenoptera stings are much more common in temperate countries. This is
despite the gross under-reporting of such stings.
 Hymenoptera stings are unvaryingly caused by the Honeybee (Apis mellifera), Paper
Wasp (Polistes annularis; Ropalidia gregaria), European Wasp (Vespula germanica),
Hornets (Vespa & Dolichovespula sp.), and Yellow Jackets (Vespula pensylvanica).
 A few incidents result from stings of fire ants (Solenopsis invicta) and rarely Jumper
Ants (Myrmecia pilosula).

Ants
 Ants release a chemical called formic
acid onto your skin when they bite.
The release of this acid, along with the
pinch from their mandibles, causes
symptoms of an ant bite.
Some people are allergic to formic acid,
which can cause a reaction in your body
beyond the site of the ant bite.

A B
Image showing swelling due to wasp sting and ant bite

Mechanical irritants
 Mechanical irritants refer to
substances or agents that cause
irritation or damage to tissues through
physical or mechanical means.
 Unlike chemical irritants that induce
irritation through chemical reactions,
mechanical irritants act by physically
disrupting or damaging the cells and
tissues they come into contact with.

 Examples of mechanical irritants
can include abrasive particles,
sharp objects, or physical forces
that lead to friction, abrasion, or
tearing of tissues.
 These irritants can cause pain,
inflammation, and tissue damage
at the site of contact.

 The effects of mechanical irritants can vary
depending on factors such as the nature of
the substance or force, the duration of
exposure, and the specific tissues involve.
 Fine or coarse particles with abrasive
properties can cause irritation when they
come into contact with the skin or mucous
membranes. Examples include sand, dust,
or metal filings.

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