BIOL354 Lecture Notes - Lecture 11: Keith Richards, Bioassay, No-Observed-Adverse-Effect Level
25 Dec 2012
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Document Summary
Risk assessment: mostly depends on the response of the target organism (bio-receptor) [+ve or -ve] The dose makes the poison, and the endpoint makes the experiment : e. g. Spring 2012: degree: lethal vs. sub-lethal (disturbed environment return to equilibrium) Dundus spencer creek: newspaper headline; fertilizer spill; dead fishes (uncommon: types: population > whole organism > biochemical/metabolic, timing: Acute: severe, rapid (<96 hours), [] applied > environmental [] Chronic/sub-acute: less severe, prolonged (>10% life span), [] applied < environmental [] Cumulative: periodical addition (time & method varies) (hard to do, good results) Chronic: mick (discontinued-control) vs. keith (treated: life stage (toxicant sensitivity): Life cycle: lethality, growth, reproduction & development over entire life cycle. Critical life stage: important stages (pre-adult: more physiological changes)(e. g. repro) Early life stage: early in development (most sensitive: physiological changes -> chronic -> population structure. Weakest link incongruity: extrapolation of critical life stage (worst case scenario) results leads to over-estimation of potential risk.
