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What does the effect of the toxin depend on?
Organism’s maturity, vulnerability (adult vs child)
What is toxicity
The ability of a substance to cause harm
What is exposure
The process by which an organism comes into contact with a substance
What is the effect
Responce of an organism to exposure.
What are the 3 groups we classify acute toxicity by?
Strongly toxic, toxic, harmful
When is a substance strongly toxic?
<25mg/kg
When is a substance toxic?
25-200mg/kg
When is a substance harmful?
200-2000mg/kg
What is a threshold level?
The effect of a substance is observed above a certain dose
What type of substances do not have a threshold + example?
Carcinogenic substances (TCDD)
How can different substances (xonobiotics) have different effects by location?
point of entry, distribution through body into the system
What are the different ways toxins act in the body?
Direct toxicity, Biochemical, Immunotoxic, Carcinogenic, Mutagenic, teratogenic, Organ specific
What is the direct toxic level
A substance acts at a critical location in an organism
What is biochemical toxicity?
The substance affects some biochemical action and affects some vital function
What is competitive inhibition?
When the inhibitor binds to an active site of an enzyme, slowing down reactions (cempetition between the inhibitor and the substrate)
What is non-competitive inhibition?
The inhibitor binds to an enzyme elsewhere, alters it and is unable to perform its function, reaction stops.
What is the immunotoxic effect?
Response to a toxin by changes in the immune system (eg. allergic reaction, immuno-suppression)
What is immuno-suppression?
Suppression of the body’s immune system and altering the ability to fight infections.
What are the basic components of the immune system?
lymphatic system, white blood cells (peripheral leukocytes)
How does an allergic reaction work?
Chemical not recognised as antigen, Binds to physiological protein molecules and chemically alters them, production of antibodies
What is carcinogenicity?
Mutation in DNA, malignant excitation of an infected tissue
What is GROUP 1 of the carcinogenic effect? + example
Proven carcinogen, vinyl chloride
What is GROUP 2 of the carcinogenic effect? + example
Expected carcinogen, DDT
What is GROUP 3 of the carcinogenic effect? + example
Potential carcinogen, polyethylene
What is GROUP 4 of the carcinogenic effect? + example
Non-carcinogen, caprolactam
HPC
highest permissable concentration
LC
lethal concentration
LD
lethal dose
NOAEL
no observable adverse effect
LOAEL
lowest observable adverse effect level