Class Notes (837,548)
Canada (510,312)
Biology (2,271)
BIOL 354 (37)
Lecture 11

Lecture 11 Summary.docx

2 Pages
208 Views
Unlock Document

Department
Biology
Course
BIOL 354
Professor
Bruce Greenberg
Semester
Summer

Description
BIOL354 – Environmental Toxicology I Spring 2012 Lecture 11: Assessment of Toxicology 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” o E.g. Jimi Hendrix (L50) vs. Keith Richards 50D ) - Categorizing Responses to Toxicants o Degree: Lethal vs. Sub-lethal (Disturbed environment return to equilibrium)  E.g. Dundus spencer creek: Newspaper headline; fertilizer spill; dead fishes (Uncommon) o Types: Population > Whole organism > Biochemical/Metabolic o 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)  E.g. Chronic: Mick (Discontinued-Control) vs. Keith (Treated) o 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) o Physiological changes -> Chronic -> Population Structure  Weakest Link Incongruity: Extrapolation of critical life stage (worst case scenario) results leads to over-estimation of potential risk - Bioassay Strategies o Definition: Biological assay, to estimate the nature, constitution & potency of a chemical by means of the observed response shown by the biological organism o Time: Time for response with set []/dose (hours to days, rarely months) o []/dose: Amount for response within set time  µg/moL (pure); mg/L & ppm (mixture of chemicals, different compounds) o Test types: Static toxicity; static renewal & flow through (difficult to setup & measure) - Dose/Concentration Response Curves o Purpose: Quantify effects of contaminants  Constant: time or []/dose  Higher potency = lower []/dose or time required for response (lower E/50 or E/L50)  Used with or without bioassay (Only need a quantifiable endpoint)  Individual effective dose: Smallest dose needed to affect or kill 1 random individual of the test population o Terminology:  Concentration: Toxicant surrounding/external to the organism  Dose: Toxicant applied internal/taken up by the organism  LC50 EC :50oncentration that cause 50% death/effect of the organisms  NOEC/NOEL: No observed effect concentration/dose  LOEC/LOEL: Lowest observable effect concentration/dose  Preferred, statistically measurable “Lack of proof is not proof of l
More Less

Related notes for BIOL 354

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit