Chapter 1 Flashcards
What is toxicology?
The study of of _ or on living organisms?
The study of adverse effect of chemical or physical agents on living organisms
What are the 2 goals of toxicology?
Toxicity of the substance/
safe/acceptable level
Why everything can be toxic?
The dose differentiates remedy and poison.
What is the difference between pharmacology and toxicology?
Pharmacology: therapeutocal
Toxicology: toxicosis or disease effect
Both goes hand in hand
What antiquity contains info on toxic plants and animals?
Ebers payrus
Dioscorides wrote what?
Materia de medica
for treatment/killing/disease
Dioscorides wrote what?
Materia de medica
for treatment/killing/disease
How did Qin Shi Huang die?
Mercury poisoning
What is the role of Cleopatra the Egypt Queen?
Ancient toxicologist
Who is Catherine de Medici?
First experimental toxicologist
Who is Catherine Deshayes?
Resposible for >2000 infants death
What’s wrong with the chimney carcinogen?
Beonzoate -> ethyl ring
Burn tar -> continuous exposure -> skin cancer
What happened in Minamata Bay?
It was a fishery bay. Hg polluants were thrown to the bay, accumulated in seafoods.
What happened in Seveso (Italy)?
An explosive release of TCDD (Dioxin)
What happened in Seveso (Italy)?
An explosive release of TCDD (Dioxin)
What happened in Bhopal, India?
A chemical leak -> 3000 deaths
What’s wrong with Spanish oil syndrome?
Pretend olive oil -> fake oil -> continuous exposure will degenerate neuron.
What toxic substance was found in paper in 1980s?
Dioxin
For the fake milk powder, what was found toxic?
melamine
For the fake milk powder, what was found toxic?
melamine
Can the adverse effects be affecting the next generation?
yes
What’s the issue for fake alcohol for tuourists?
The ethanol was mixed with methanol, where methanol is inedible. Some people lack the enzymes to break down.
What are the 3 classifications of toxicology?
- Descriptive toxicology : What do we expose to? What type of toxin?
- Mechanistic toxicology: Why will it induce adverse effect?
- Analytical toxicology: How much is the dose?
What are the 4 types of applied toxicology?
- Occupational toxicology
- Clinical toxicology
- Forensic toxicology
- Regulatory toxicology
- Developmental toxicology
State the definition of toxicity
The degree to which a susbstance can harm animals or humans
What are the 3 types of toxicity?
- Acute
- Subchronic
- Chronic
Memorize the definition of acute toxicity
Acute toxicity describes the adverse effects of a substance that results from either a single/multiple exposures in a short space of time (< 24hrs). The adverse effects should occur within 14 dats of administration of the substance.
- Exposure is within 24 hrs
- Adverse effect within 14 days
- single/multiple exposure
- A single substance
Memorize the definition of subchronic toxicity
The ability of toxic substance to cause effects for more than 1 year but less than the lifetime of the exposed organism. Usually following exposure to a repeated/continuous dose over a period up to about 90 days.
- Exposed to repeated/ continuous exposure
- Up to 90 days
- One single compound
- Adverse effect > 1 year < life span
Memorize the definition of chronic toxicity
The ability of a substance or mixture of substances to cause harmful effects over an extended period. Usually upon repeated or continuous exposeure, some can last for the entire life of the exposed organism.
- Mixture of substances/ single substance
- Exposure can be the whole life time of the organism
- Adverse effect can be entire life
What are the 8 classifications of toxicants?
- Target use
- Intended use
- Source
- Special effect
- Physical state
- Toxicity
- Chemical composition
- Mechanism of action
Describe immediate toxicity
- Equivalent to acute toxicity
- Cyanide, arsenic
- Easy to detect and can link a particular exposure to a particular chemical.
Describe delayed toxicity
- Long latency period
- Can be 20-30 yrs after exposure before tumours are observed
- The long delayed latent period makes if diffcult to demonstrate/prove the cause&effect
- Asbestos 石棉 (1 exposure can cause adverse effect)
Toxic effects can be reversible or irreversible, T/F?
T
Toxic effects can be reversible or irreversible, T/F?
T
What is the most important factor in determining the reversibility of damage?
Regeneration capcity of tissues
High regeneration capacity makes it better to revover from toxic insult
Is liver damage reversible? Why?
Yes, cuz high regenerative capacity of the liver.
Is brain cell damage reversible? Why?
No, CNS has a limited regenerative capacity
What is special about oedema of the respiratory mucosa?
- It is a reversible toxic effect
- But it can have irreversible consequences
- Asthmatic person exposed to SO2 (irritant), oedema can lead to restriction of airways -> death
- Although oedema itself can be reversed
What are the 2 natures of toxicity
Local (bee) or systematic (snake)
Give some features of systemic effects of toxicants
- Absorbtion and distribution from entry point to a distant site, where adverse effects are produced.
- the target organ is not the site of the highest concentration
- CNS, circulatory, skin, blood and haematopoietic system, visceral organs….
- Muscle and bone are less frequent
Recall the toxicity rating of oral human dose
Read lecture notes, 5 as a unit
What is the meaning of LD50?
The dose that kills 50% of the animals
What are the differences between public perception and scientific evaluation/reality?
- Perception thinks synthetic toxins pose greater carcinogenic hazards than natural toxins
- Proportion of natural chemicals that is carcinogenic when tested in both rats and mice is the same as for synthetic chemicals
- All chemicals arer toxic at some dose
