lecture toxicity testing

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