Ecotoxicology

Effects on individuals

Significance/Relevance of acute tests

Effects on individuals – toxicity tests

• Acute toxicity values are no biological constants• Variations between laboratories and experimental

replicates • Differences among species and individuals at different life-

stages • Acute toxicity values are not sufficient for ecotoxicity-

evaluation • Results not transferable to chronic toxicity and no

inclusion of indirect (ecological) effects• Enhancing the significance by using several species, e.g.

SSDs

Species Sensitivity Distributions (SSDs): e.g. CPF

Effects on individuals – toxicity tests Maltby et al. 2002

Lecture contents

• IntroductionPhenomenons and principles

• Exposure (Environmental chemistry)Chemicals in the environment Classes of chemicals Chemical properties Processes

• Effects on individualsDose-response-relationships Acute and chronic toxicity Toxicity testsSubcellular tests, BiomarkerCombined effects

Effects on individuals

Toxicity tests (contd)

Overview of aquatic toxicity tests

Effects on individuals – toxicity tests Fent 2003

Aquatic tests - Algae

Effects on individuals – toxicity tests

72-h EC50: inhibition of cell proliferation and photosynthesis

Fent 2003

Aquatic tests - invertebrates

Effects on individuals – toxicity tests

Daphnia: Acute (48 h) swimming capacity, 21-days repro testChironomus: Acute (96 h) mortality, 28-days reproduction test

(sediment and water exposure)

Daphnia magna EUDaphnia pulex USChironomus riparius EUChironomus tentans US

Fent 2003

Aquatic tests - fish

Effects on individuals – toxicity tests

Fish: - acute (96 h) mortality, - chronic 14-28 days mortality,-ELS, FFLC (fertility, reproduction),- in-vitro cell cultures (genotoxicity)

TroutFathead minnowBluegillZebrafishMedakaCarp

Fent 2003

Comparison ELS and FFLC: NOECs for zebrafish

Effects on individuals – toxicity tests Fent 2003

Effects on individuals

Subcellular tests, Biomarkers

Molecular effects on cells

• Adverse effects on cellular processesa. Disturbance of the Ca 2+ - and Ion-metabolismIncrease of Ca-conc.: Activation of degradation enzymes, destruction

of the cytosceleton, membranes and DNA b. Inhibition of the energy synthesis (ATP, photosynthesis)c. Disturbance/inhibition of enzymatical processesGlutathione to protect Proteinthiole against binding of pollutantsd. Disturbance of the growth regulation

• Effects on cellular structuresInteraction with membrane structuresChange or destruction of membranesInfluence on organelles: mitochondria, lysosomesInfluence on cell nucleus: genotoxicity, cancerogenity

Effects on individuals - Subcellular tests, Biomarkers

Expl: Molecular effects of organotin-compounds

Effects on individuals - Subcellular tests, Biomarkers Fent 2003

Effects on structure and function of cell membranes

Effects on individuals - Subcellular tests, Biomarkers Fent 2003

Permanent cell cultures: Permanent Hepatoma cell line

Germany, 1991: ca. 200 000 fish used in toxicity testing

Effects on individuals - Subcellular tests, Biomarkers Fent 2003

Fish cell test for cytotoxicity

Effects on individuals - Subcellular tests, Biomarkers Fent 2003

In vitro Neutralred-Assay

Effects on individuals - Subcellular tests, Biomarkers Fent 2003

Biomarkers - Summary

• (Subcellular) biologic reaction to environmental chemicals Receptor bindingBiochemical response: Induction of detoxification enzymes, inhibition of

enzymesPhysiological response: avian eggshell-thinning, imposex of fish embryos

• Advantages and disadvantages of subcellular tests or biomarkers?• Advantages

SensitivityDetection of exposure and assessment of mechanisms of toxicityEthical aspects concerning vertebratesScreening tests

• DisadvantagesLack of knowledge on the whole organism: metabolism Chronic effects not well representedResults with little relevance for populations/communities/ecosystems

Effects on individuals - Subcellular tests, Biomarkers

Effects on individuals

Combined effects

Combined effects: overview

Effects on individuals – combined effects

• Two or more substances coexistant: „Mixture toxicity“• Pollutant and another abiotic stressor

Mixture toxicity: Additive effects, Synergism, Antagonism

Effects on individuals – combined effects Moriarty 1988

Calculating mixture toxicity (assumption: additive effect)

Effects on individuals – combined effects Hund & Kördel 1996

Prediciting the mixture toxicity of an increasing no. of substances?

Effects on individuals – combined effects

Funnel Hypothesis

Warne & Hawker 1995

Funnel Hypothesis: real data

Effects on individuals – combined effects Warne & Hawker 1995

Mixture toxicity: substances with similar MoA

Effects on individuals – combined effects

Concentration addition

Grimme et al. 1998

Mixture toxicity: substances with differing MoA

Effects on individuals – combined effects

Response addition

Grimme et al. 1998

Fluoranthene and UV: Effects on frog embryos

Effects on individuals – combined effects

Heavy metal contamination and UV in the Antarctic

Effects on individuals – combined effects

Heavy metal contamination and UV in the Antarctic

Effects on individuals – combined effects

Survival of the amphipodParamorea walkeri

Combined effects: overview

Effects on individuals – combined effects

• Two or more substances coexistentAdditivity, Antagonism, SynergismMixture toxicityFunnel Hypothesis

• Pollutant and another abiotic stressorUV-induced toxicity of PAHsHeavy metals and UV in the Antarctic

• Examinations on different levels

• Important termsAcute, chronic, 96-h LC50, 48-h EC50, NOEC, LOEC, NOEAEC

• Linear and non-linear dose-response-relationships

• Acute and chronic toxicitySpecies differences up to factor 10000Acute (mortality) : chronic (sublethal) = 1 : 1 to 1 : 10000

Effects on individuals - summary

• Species Sensitivity Distributions (SSDs)

• Ecotoxicological testsOECD (GLP), 91/414/EC, REACHAlgae, water-flea, fish as standardset

• Subcellular tests, BiomarkersAlternatives to fishtests?

• Combined effectsMixture toxicityChemical and abiotic stressor

Effects on individuals - summary

Lecture contents (cont.)

• Effects on populations and communitiesMicro- and MesocosmsInteractions, indirect effectsIn situ systemsField studies: ecosystem-effects

• Risk assessment and risk managementAssessment schemesProbabilistic methodsAuthorization of chemicalsRisk mitigation strategies

Organisational

• See you next week• Everybody to think about a question/statement related to

ecotox at the level of individuals for next Tuesday