Chemcal Risk Assessment Flashcards
Define risk and provide its equation
A risk is the probability of something undesirable happening.
Risk=P*C
P: probability of the unwanted event happening
C: the consequences of the event.
What are they three questions a risk assessment will provide answers to ?
- What can happen?
- How likely is it ? ( probability)
- What are the consequences is it happens?
What are the general principles of chemical risk assessment ?
- Identify that there is a hazard
- Divivde the hazard in to exposure analysis ( how much chemical is there , where is it , is it taken up ?) and effect analysis ( what type effect will occur at which dose ).
- Characterise the risk.
Both exposure analysis and Effect analysis can also be referred to as alternate names what are they ?
Exposure analysis: Predicted environmental concentration (PEC) the expected concentration in the environment
Effect analysis : Predicted no effect concentration (PNEC) the long term safe concentration for plants and animals
What are the different risk characterisations?
If PEC/PNEC< 1 = okay (low risk)
If PEC /PNEC >1 = concern ( high risk)
What is the major problem with risk assessment of chemicals?
The major problem is the difficulty in applying findings obtained from tests done in a laboratory on a singular species to draw conclusions about how the same chemical might affect natural ecosystems with numerous organisms.
Is this true or false .
Saving the most sensitive species is expected to save all other species in the ecosystem.
True
Detail the two steps involved in determining PNEC
- Perform standard Tox tests : here you identify the most sensitive species in an ecosystem and run tox tests.
- Extrapolation: here you begin to predict what the effects will be in the ecosystem after studying the effects on your sensitive species.
What is the formulae for PNEC?
PNEC= observed toxicity / assessment factor or safety margin
What is the formulas for risk ratio or Risk quotient (rq)?
Rq= PEC/PNEC
What is the main aim of water frame work directive and when was it established ?
The main aim is to develop technical guidelines legally binding to ensure environmental quality standards.(EQS)
What is Environmental quality Standards?
These are tools used to assess the chemical status of water bodies.
The pollutants in the env. can be grouped into two name them and the information known about them.
- Priority pollutants : regulated under the WFD environmental quality standards. Annual average concentration is known . Maximum allowable concentration is known. Made up of 29 chemicals 4 metals.
- Emerging pollutants : not regulated, little to no studies done about them, may cause harm to the environmental ecosystems. Comprises of pharmaceutical products, personal care products, flame retardants detergents and many more. There are sometimes challenges in detecting them because technology to detect them have not yet been invented.
Answer true or false to this question :
Mixture toxicity has a higher effect than single components
True
There are three possible effect of chemical mixtures on organisms. Name and define them.
Additive effect: this is when the effect of two or more substances used together is equal to the sum of the effect of the substances used individuallly.
Synergistic effect : this is when two or more substance act together to enhance their effects. In this case the sum of their effect together is way more than the sum of their individual effects.
Antagonistic effect: this is when the sum of the effect of two or miOre substances is less than the sum of their individual effects.
