toxicity test methods l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Toxicity Test Methods PowerPoint Presentation
Download Presentation
Toxicity Test Methods

Loading in 2 Seconds...

play fullscreen
1 / 22

Toxicity Test Methods - PowerPoint PPT Presentation


  • 677 Views
  • Uploaded on

Toxicity Test Methods. Chapter 4. Introduction. Working knowledge of standard test methods very important in understanding the field of environmental toxicology Both strengths and weaknesses needed to interpret test results

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Toxicity Test Methods' - finian


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
introduction
Introduction
  • Working knowledge of standard test methods very important in understanding the field of environmental toxicology
  • Both strengths and weaknesses needed to interpret test results
  • Methods were mostly developed in the ’80’s with some modifications since then
  • Most “old” tests have not been replaced with new tests but rather have been “tweaked” over the years
overview
Overview
  • Toxicity tests can range from cell cultures to ecosystem function
  • Most tests fall under two general classifications
    • Single-species
      • Relatively cheaper, shorter, low ecological realism
    • Multi-species
      • Tend to be longer, more expensive and have higher ecological realisms
single species toxicity testing
Single species toxicity testing
  • Daphnia 45-h Acute Toxicity Test
    • Most widely used test for evaluating toxicity of water
    • Three primary species
      • Daphnia magna – general testing
      • Ceriodaphnia dubia – chronic testing over an acute time period
      • Daphnia pulex – evaluation of stormflow toxicity
    • All are easy to culture when published guidelines are followed but some differences in testing procedure
    • Note: algal tests are most likely to show hormesis effect
single species toxicity testing con t
Single species toxicity testing (con’t)
  • Algal 96-h growth toxicity test
    • Examines toxicity to freshwater and marine algae
    • Algae are extremely important because they generate most of the primary productivity in aquatic and marine sytems  effects on algae can have high impact at higher trophic levels in ecosystem
single species toxicity testing con t11
Single species toxicity testing (con’t)
  • Acute toxicity tests with aquatic organisms
    • Multiple tests using a variety of fish, amphibians and macroinvertebrates
    • Endpoint is either death or immobilization
    • More difficult to culture or obtain as test organisms so often use animals collected from the wild or available commercially as “bait”
      • Test organisms may need to be acclimated to laboratory conditions
      • More variability in response because of increased heterogeneity of gene pool
      • Locally collected organisms may provide better indication of effect of xenobiotics on local ecosystems
      • See table 4.5 (p. 80-82) for specific test organisms and test conditions
single species toxicity testing con t13
Single species toxicity testing (con’t)
  • Terrestrial vertebrate toxicity test
    • Mammals, birds
    • Toxicant usually introduced in food (gelatin capsule or gastric lavage)
    • Mammals  surrogate for human health effects
    • Birds  effect of pesticides on non-target species
    • Both animal groups are usually tested for 90 days
    • Endpoint death, test may include urinalysis, hematology, necropsy
single species toxicity testing con t16
Single species toxicity testing (con’t)
  • Frog Embryo Teratogenesis Assay: Xenopus (FETAX)
  • One of few standardized amphibian-based toxicity tests
  • Designed to test teratogenicity of chemicals or effluent using the African Clawed frog as a surrogate for humans
  • Good correlation between known human teratogens and FETAX results
multi species toxicity test
Multi-species toxicity test
  • Artificially contained communities
  • Must contain two or more interacting species
  • Trying to simulate environmental realism but often want to reduce heterogeneity in test conditions
  • Wide range of size and complexity in multi-species test protocols
microcosms and mesocosms
Microcosms and Mesocosms
  • Microcosms
    • Small (can usually be picked up)
    • Assembled to include specific components
    • Highly defined artificial ecosystem
    • Easy, cheap to replicate
    • Moderate level of environmental realism
  • Mesocosms
    • Larger (kiddie wading pool to 3 acre ponds)
    • May include volunteer components so system is less defined
    • Expensive, hard to maintain
    • High level of environmental realism
uses of microcosms and mesocosms
Uses of microcosms and mesocosms
  • 1° - Test for ecosystem level effects of pesticides (FIFRA microcosms)
  • Effects of oil spills on marine ecosystem
  • Effect of draining aquaculture ponds into adjacent stream
  • Any ecosystem level test