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Lecture 12

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University of Waterloo
BIOL 354
Bruce Greenberg

BIOL354 – Environmental Toxicology I Spring 2012 Lecture 12 – Toxicity Test Methods Categories and Types of Tests - Whole organism: Acute (Life/Death); Chronic (Growth or Reproduction); & Multi-species (Life or Growth) - Biomarker/Bioindicator: Biochemical indicator for respiration, mutations, etc. Selection Criteria for Tests - Widely available, culturable w/ sufficient quantities, known history & genetics - Positive controls require known relative toxicity of various toxicants for the specie tested - Specie tested should have a representative sensitivity; interactions b/w organisms & environment must be understood in multi-species tests - Regulatory agency mandates (the species tested must be relevant to the environment) Examples of Tests - Daphnia magna – 48 hours acute test after 48h starvation test o Freshwater flea: Large (2mm), culturable, widely available o Procedure: 10 neonates (<24h old, recently hatched); 5 []s & 1 Negative control in triplicates; Room light; Static renewal (Periodically renewed solution); Lethal end point (immobility or absence); Positive control (Can be done with many chemicals) o Advantages:  Rapid, cheap, small amount of solution = less waste generated  Pathogenic (No gender) - Replication  Can be geared into chronic, life cycle (2 weeks) tests w/bioindicator assessments  High sensitivity to contaminants o Disadvantages:  High sensitivity to contaminants & static renewal (over detection of contaminants)  Starvation test causes extra stress (Might contribute to high sensitivity)  Steep dose response curve (Easy to find L50but rapid change over short period) o E.g. Phenanthrene (PAH) vs. Pheanthrene Quinone (Oxidized PAH photo-oxidation)  Same mechanism, but LC i50much less for O-PAH than for PAH - Lemma gibba – 8 days growth assay o Aquatic plant: Large (fronds 3-5mm diameter & 4-5/plant), culturable, widely available o Procedure: 3 colonies (10 fronds); From log phase (rapid growth) culture to synthetic growth (trace metals) growth medium; 5 []s & 1 Negative control in triplicates; 10x room light; Static renewal (replenish chemical); Growth inhibition end point (Frond #); Positive control (Herbicides) o Advantages:  Rapid, cheap, small amount of solution = less waste generated  Can be used w/ other bioindicator assessments end-points  Lower than average sensitivity to contaminants (biomass -> tolerance) o Disadvantages:  Low sensitivity to contaminants (under detection of toxicity)  Sensitive to light quality; EDTA in media (slow release of nutrients); Labor intensive o E.g. Photoinduced toxicity of PAHs (Growth rate & Chlorophyll) - Hyalella Azteca – 1 to 4 week for growth & survival test or 4 weeks reproduction test(Aquatic or Sediment) o Aquatic amphipod: Small (2-4mm), culturable, widely available o Procedure: 7-14 day old; Feeds on fish food; 5 []s & Negative control in triplicates; Static renewal; Room light; Measurements end point; Positive control (Cu or Cd)
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