Toxicology Case Studies Flashcards
What does Paul Anastas define Green Chemistry as:
“Green Chemisty is the design of chemical products and processes that reduce or eliminate the use and/or generation of hazardous substances to health or the environment”
What is Toxicity?
An adverse health effect caused by a chemical
What is Toxicology?
The study of how chemicals interfere with the normal function of a biological system to cause an adverse health effect
(particularly human health)
Paracelsus is a 15th centry physician and the ‘Father of Toxicology’
What does her say about toxicology?
“All substances are poisons; there is none which is not a poison. The right dose differentiates a poison and a remedy”
What is ‘LD₅₀’
- The median dose of a material that cases the death of 50% of tested organisms
- When delivered all at one
- (Obviously this cannot be tested for humans)
What is ‘LC₅₀’
The median concentration of a material that causes the death of 50% of tested aquatic organisms
The higher the LD₅₀ or LC₅₀ of a given material….
…. the less toxic it is
Why can we not always use animal data to indicate the toxicity of a compound on other animals or humans?
Sometimes an animals has particular sensitivity to a compound
Toxicity is a function of…
Toxicity = f(does, expose, time)
* The real problems are difficulty of testing mixtures of chemicals (because of the number of possible combination)
* Also, chemicals can be transformed in the environment - perhaps resulting in worse effects
List some determining factors of Toxicity
- Route of Exposure (oral, dermal, inhalation)
- Dose
- Frequency of exposure
- Duration of exposure (some species can be sick hence reducing the duration)
- Biological properties (age, gender etc)
- Chemical properties
What does In vivo mean
(relative toxicity testing)
- In or on a living organism e.g. animal or human
- Animal models have been used for a long time
What does In Vitro mean
(relative to toxicity testing)
- Within the confines of a test tube or lab dish
- Became more plausible due to high throughput screening
- Tests individual cells, hence the effect may be seen much more rapdily
What does “in situ” mean?
In its original place
What does “In silico” mean?
Using computers and computer simulations to predict the effect of chemicals
Toxicity assessments that use computation resources to organise, analyse, model, simulate or predict the toxicity of chemicals
Would you use ‘In Silico’ testing on its own?
Probably not
Instead to compliment ‘in vitro’ and ‘in vivo’ toxicity tests to potentially minimise the need for animal testing, reducing the cost/time of toxicity test and improve predictions
Brings a unique advantage of being able to estimate toxicity of chemicals before they have been synthesised
A paper released in 2020 talked about how the Coho Salmon were found to be dying when trying to breed in the urban creeks in the US Pacific Northwest
What was the problem?
- After analysis of over 200 compounds
- 6PPD was found to be the issue, tho not toxic itself
- It is a tyre additive, were when the rubber wears off the tyre additive gets washes out by the rain and runs into the creeks
- It then becomes oxidised by ozone to form 6PPD-quinone which is what was killing the salmon
- The quinone was 100x more toxic than the original 6OOD additive
What does Green Toxicology promote?
New techniques to..
* reduce animal testings
* the amounts of chemicals used + disposed of during tests
* Increased consideration of toxicity in synthesis, use and regulation of chemicals
