2. Introduction
• The injury caused by the toxians is called toxic
effects.
• The damages caused by a toxin through out the
body constitute is systemic toxic effects.
• The distribution of toxicants and toxic metabolites
throughout the body ultimately determines the
site, where toxicity occurs.
• The dosage is the most important and critical factor
in determining the toxicity response in the body.
4. Acute toxicity
• The acute toxicity refers to the harmful effects
produced immediately by a toxic agent by a single
exposure to the substance.
• The Toxicity occurs almost immediately in hours or
days after an exposure.
• An acute toxicity exposes is usually a single dose or
a series of doses received within a 24 hour period.
• The adverse effect of an acute toxicity should occur
within 14 days of the administration of the
substance.
5. • Ex:- in 1989, 5,000 people died and 30,000
permanently disabled due to exposure to methyl
isocyanate from an industrial accident in Bhopal
India.
• There is some following acute toxicants
• I) Hydrogen cyanide. II) Nitrogen dioxide
• III) Hydrogen sulphide Iv) Arsenic
• Acute poison enter through the body is inhalation,
ingestion, absorption etc..
• Acute toxicity is expressed in
• LD50:- Lethal dose 50
• LC50:- Lethal concentration 50
6.
7. • The lower the LD value, the less it takes to kill 50%of
the population and their for the greater acute toxicity
of the chemical.
• Acute toxicity have a many symptoms some are
headache, blindness , dizziness,Asthma, pain , metal
impairment.
• Treatment like:-
• Emergency showers
• Emergency eye washes
• Activated charcoal used to bind and remove harmful
substance consumed orally
• Enhanced excretion:- poison can be removed by
diuresis, hemodialysis,peritoneal dialysis.
8.
9. Sub-acute Toxicity
• To determine toxicity after repeated administration
of the test material.
• Repeated dose toxicity testing using oral
administration of a test substance in rodents for 28
and 90 days is used to evaluate sub-acute toxic
effect primary effect on various organ system and
to establish a no observed effect level.
• The animals are observed individually after dosing
periodically during the 24 hours and Daily
thereafter for 14 days.
10.
11. Chronic toxicity
• It represents cumulative damage to specific organ
systems and takes many months or years to become
a recognizable clinical disease.
• Adverse effects associated with chronic toxicity can
be directly Lethal but are more commonly sub
Lethal including changes in growth, reproduction or
behaviour.
• In chronic toxicity the ill effect are produced after a
long time of exposure to toxins it is called delayed
health effect.
• Chronic effect develop slowly.
12. • Chronic effect are produced in two ways namely that is
• i) repeated exposure of the toxin
• ii) continuous exposure of the toxin
• There is some chronic toxicants like
• asbestos , ionizing radiation , heavy metals like
mercury ,cadmium, lead etc.
• Cancer, hearing loss, Kidney Disease ,convulsion,
alcoholics paralysis, damage to brain etc. are chronic
disease effect.
• Ex- Cirrhosis in alcoholics who have ingested ethanol
for several years.
• Pulmonary fibrosis in coal miners ( black lung disease)
13.
14. Sub- Chronic Toxicity
• Sub-chronic toxicity results from repeated exposure
for several weeks or months.
• This is a common human exposure pattern for some
pharmaceuticals and environmental agents.
• Subchronic toxicity study is available to studies of
TCDD have been reviewed by the US EPA 1984 ,1985
and WHO / IPC 1989.
• Ex- workplace exposure to lead over a period of
several weeks can result in anaemia.
