lecture toxicity testing
TRANSCRIPT
Marine Pollution and Ecotoxicology – 2008
Introduction to Toxicity testing of chemicals
Practical course
Marine Pollution and Ecotoxicology – 2008
The role of toxicity testing in ecotoxicology
Aquatic toxicity: The negative effects of a substance on the living organisms (obtained from testing on aquatic animals and plants)
Degradability: The persistence of the substance in the environment (dependent on molecular chemistry of the chemical)
Bioaccumulation: The accumulation of a substance in living organisms, which may or may not lead to a toxic effects (often obtained by experimenting and /or modeling or use of bioconcentration factors (BCF) or bioaccumulation factor (BAF).
Toxicity is among 3 specific properties of a chemical used to describe its potential hazard to the aquatic environment
Marine Pollution and Ecotoxicology – 2008
The goal of toxicity tests
To determine the level (concentration) of a chemical in the water that will cause unacceptable negative effects
on the environment
How do you calculate PNEC from toxicity data?
PECPNEC
Risk Quotient =
Remember… ERA
Marine Pollution and Ecotoxicology – 2008
In the case of aquatic ecotoxicology, preferably toxicity data should be obtained from species representing 3 different trophic levels
PNEC is traditionally calculated from toxicity studies
algae
invertebrate
fish
Principle Principle
How is toxicity data presented?
Marine Pollution and Ecotoxicology – 2008
Some terminologies
Effects: e.g.
Accumulation, Cellular, Mortality, Behaviour, Ecosystem, Physiology, Biochemical, Growth, Population, Reproduction
End-point: Concentration of the chemical in the water at which a certain Level of the Effect is observed e.g.
Concentration in the water at which 50% of the experimental organisms are dead in 48h or LC50 (48h)
Concentration in the water at which 5% of the new born have deformations or EC5
Marine Pollution and Ecotoxicology – 2008
The best data set should include results from 3 trophic levels (algae, invertebrates and fish)
Long-term end-points are preferred i.e. NOEC
If no long-term data is possible or available then use short-term toxicity data i.e. LC50 or EC50.
Data needed to calculate PNEC
Marine Pollution and Ecotoxicology – 2008
Available dataAssessment / application factor
At least one short-tern L(E)C50 from each of three trophic levels of the base-set (Fish, Daphnia and
Algae) 1000
One long-term NOEC (either fish or Daphnia) 100Two long-tern NOECs from species representing two trophic levels (Fish and/or Daphnia and/or
algae)50
Long-term NOECs from at least three species (nornally Fish, Daphnia and algae) representing
three trophic levels10
Calculation of PNEC based on available toxicity data
Use of toxicity data
Marine Pollution and Ecotoxicology – 2008
General principal:
Dose versus Effect relationships
Dose-effect curves and how to determine NOEC
Dose / exposure concentration
effect individual Population Ecosystem
Marine Pollution and Ecotoxicology – 2008
Determine a dose / concentrations at which no significant toxic effect is observed
How to determine toxicity
Dose / exposure concentration
effect
No Observed Effect Concentration (NOEC)
Marine Pollution and Ecotoxicology – 2008
Toxicity of essential and non-essential substances
Marine Pollution and Ecotoxicology – 2008
How to determine toxicity
Dose / exposure concentration
effect
Effects and End-points
1. Acute effect • Mortality
End-points LC values i.e LC50
2. Chronic effects • reproduction• growth e.t.c.• species distribution• biodiversity e.t.cend-points EC values i.e. EC50
NOEC
Marine Pollution and Ecotoxicology – 2008
• Determine the LC50(24h) of copper or cadmium on artemia salina
• For reporting compare and discuss the toxicity of these two heavy metals.
Practical exercise