Physical-chemical fate properties
Aquatic ecotoxicity test
Partitioning
Degradation
Various
100
Which substance is most volatile from its pure state at 20oc A: vapor pressure 100 Pa at 20oC B: vapor pressure 200 Pa at 20oC C: vapor pressure 200 Pa at 15 oC
Substance C as it has the highest vapour pressure at 20oC
100
When conduction fish tests there are three systems which can be applied. One is a static test system, what are the two remaining systems.
Flow through and semi-static
100
What does the abbreviation EPM stand for?
Equilibrium partitioning method
100
What is the difference between ‘Primary biodegradation’ and ‘Ultimate biodegradation’?
Primary biodegradation is a structural change of a substance (transformation), whereas ultimate biodegradation is degradation resulting in the formation of CO2 and biomass (mineralisation)
100
In a GLP study who is the single point of study control?
Study director
200
Substances A, B and C are present in water at the same concentration. Which substance would you expect evaporates the fastest from a water phase - and why A: Vapor pressure 100 Pa; Mw=100 g/mole; Water solubility = 2 mg/L B: Vapor pressure 200 Pa; Mw=100 g/mole; Water solubility = 10 mg/L C: Vapor pressure 200 Pa; Mw=100 g/mole; Water solubility = 5 mg/L
A: H=100*100/2 Pa m3/mole = 5000 Pa m3/mole B: H =200*100/10 Pa m3/mole = 2000 Pa m3/mole C: H =200*100/5 Pa m3/mole = 4000 Pa m3/mole A is expected to evaporate the fastest, as it has the highest Henrys constant
200
During a test it is important to measure pH, oxygen and temperature- why?
These are all factors which can influence the outcome of the test - for example these factors may have an effect on survival
200
For which of the following substances should the fate calculcations not be based on a logKow-correlation A: Dodecane B: 4-Tert-butyl-iso-nonane C: Cobber sulphate
C, as it is an inorganic substance
200
What are the requirements to biomass (in mg SS/L), duration (in days) and pass level(s) (in %) for a positive ready biodegradability test?
≤ 30 mg SS/L, 28 days, 60% (BOD or CO2) or 70% (DOC removal)
200
What is the relevant environmental compartment for a respiration inhibition test?
Sewage treatment plant (microorganisms in the aeration tank)
300
Consider three hydrocarbons A, B and C. Log Kow (A) = 2.8 Log Kow (B) = 5.5 Log Kow (C) = 3.0 From this information, which substance would you expect to adsorb most strongly to soil and sediment?
Substance B, as it has the highest logKow. As the substances belong to the same chemical familiy, they are expected to adsorp in a similar manner.
300
Which test is considered the most sensitive of the fish tests and why?
OECD 210 “Fish early life stage test “ . It covers several life stages of the fish from the newly fertilized egg through hatch to early stages of growth.
300
Is equilibrium between the various environmental compartments obtained at steady-state?
No, environment seeks equilibrium, however the steady-state depends on the various process rates
300
What is the recommended concentration of test substance in a biodegradation simulation test?
1-100 µg/L
300
In general terms which substance properties allows the registrant not to make an environmental exposure assessment?
The substance has a very low potential for bioaccumulation, and a low toxicity and is readily degraded
400
Which of the below substances A, B and C do you expect has the highest removal in an STP (measured as % removed from the water phase) and why. None of the substances are biodegradable! The molecular weight is 100 g/mole of A, B, C. A: vapor pressure 10 Pa, water solubility 1 mg/L, logKow=3 B: vapor pressure 1 Pa, water solubility 0.1 mg/L, logKow=7.5 C: vapor pressure 10 Pa, water solubility 100 mg/L, logKow=3
Substance B, as it (together with A) has the highest volatilty (Henrys constant). But as B also has the highest logKow, it will also adsorb strongest to the sludge
400
Mention 3 factors which should be kept in mind regarding the test substance when choosing the two test concentration for a bioconcentration test
1)Water solubility (Concentrations should be below the solubility of the test substance). 2)The analytical detection limit (concentration should be at least 10 times the limit). 3)The LC50: The highest concentration should be around 1% of the LC50.
400
Which substance has the highest potential for bioaccumulation: A: logKow = 5; BCF (Fish) = 5000 B: logKow = 6; BCF (fish) = 2000 C: logKow = 4; BCF (fish) = 4000
Substance A, as it has the highest BCF
400
What is the half-life in freshwater that leads to fulfillment of P in the PBT assessment?
>40 days
400
Which substance is -according to the following data - the most ecotoxic? A has a higher EC50 than B. B has a lower EC50 than C?
Substance B, as it has the lowest EC50
500
Mention 3 properties that makes a substance a ’difficult substance’
High volatility, Rapid degradation, Low water solubility (<100 mg/L)
500
Two toxicity studies with fish have been carried out for a substance with a logKow of 4: Experiments 1: 50 g rainbow trout. Result: LC50 = 12 mg / l Experiment 2: 200 mg zebra fish. Result: LC50 = 2 mg / l Based on bioaccumulation considerations - explain the observed differences in the LC50
Within 96 hours, it is possible to achieve a balanced equilibrium in test with zebrafish and thus the maximum toxicity will be reached. In the experiment with rainbow trout, an equilibrium will not be reached within the 96 hours due to fish size, and the substance maximal toxicity is thus not obtained.
500
Which of the following substances would you think leaches mostly to ground water from soil: A: Ready biodegradable; Kd=500 l/kg B: Readily biodegradable; Kd = 10 l/kg C: Not biodegradable; Kd= 10 l/kg
C as it has the lowest Kd (together with B) and is not degradable
500
The laboratory manager decides to apply OECD 301 A to measure the readily biodegradability of a very hydrophobic hydrocarbon. Is this a wise decission and why (not)?
OECD 301 A is based on DOC. Sorption may interphere with DOC measurements. So this was not a wise decission. Note that the laboratory manager is a chemical engineer - not knowing much about biodegradation!
500
What is the difference between a GLP test protocol amendment and a deviation ?
Amendments: an intended change to the study plan after the study initiation date. Deviations: an unintended deviation from the study plan after the study initiation date
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