ESM 202

1
ESM 202

• Assessing the Effects of Chemicals on Ecosystems

2
Human vs. Ecotoxicology

• Human Toxicology
• Deals with acute (e.g. occupational health) and
  chronic (e.g. cancer, liver damage) human health
  issues
• Focus on individuals
• Goal acceptable risk to human receptors

• Ecotoxicology
• Deals with effects on all other organisms,
  including acute and chronic effects
• Focus on populations
• Goal minimize loss of biota and ecosystem
  integrity

3
(No Transcript)
4
Effect of Chemicals
5
(No Transcript)
6
(No Transcript)
7
Methods

• Toxicity Tests/Bioassays
• Acute
• Chronic
• Field Assessments/Surveys
• Bioaccumulation Studies
• Biomarkers
• Microcosm Mesocosm Studies

8
Toxicity Tests

• Provide a direct measure of biological uptake of
  the toxicants
• Establish link between site contamination and
  adverse ecological effects
• May provide info on synergistic or antagonistic
  interactions among chemicals
• Direct extrapolation of lab to field should be
  carefully evaluated
• May do an in situ toxicity test under field
  conditions

9
Toxicity Tests

• Toxicity tests can be used for both aquatic and
  terrestrial systems
• Aquatic tests are more developed
• Endpoints are mortality, growth and/or
  reproduction
• Vertebrates
• Rodents
• Fish
• Birds

10
Toxicity Tests

• Invertebrates
• Insects
• Amphipods (crustacea related to shrimp and krill)
• Plankton
• Microbes
• Luminescent bacteria (Microtox)
• Plants
• Aquatic or terrestrial
• Vascular or non-vascular

11
Toxicity Tests

• Environmental Matrices
• Water
• freshwater
• estuarine/marine
• Sediments
• freshwater
• estuarine/marine
• Soils
• Used to develop Water Quality Criteria (WQC) for
  different uses

12
Toxicity Tests/Bioassays

• Standardized methods
• EPA
• US Army Corps of Engineers
• ASTM
• Org. of Economic Cooperation and Development
  (OECD)
• Aquatic Toxicity tests for
• fish
• invertebrates
• algae

13
Acute Aquatic Toxicity Tests

• Most frequently used (short less expensive)
• Relates dose (Cw x time of exposure) to time of
  death for a particular test organism
• Produce concentration/response curve
• Ranges from 1 to 4 days for aquatic tests and up
  to 10 days for assessment of sediment toxicity
• Done in laboratory under controlled conditions

14
Acute Aquatic Toxicity Tests
15
Chronic Aquatic Toxicity Tests

• Longer tests 7 - 30 days
• Objective is to expose for at least 1/10th of
  lifetime
• Effect of different Cw on growth, reproduction,
  behavioral, physiological or other biological
  function
• Sub-chronic only exposed during part of
  life-cycle (usually early stages)
• Life-cycle tests have been done for only a few
  contaminants

16
Chronic Aquatic Toxicity Tests
17
Chronic Aquatic Toxicity Tests
18
Sediment Toxicity
19
Sediment Toxicity
20
Toxicity Tests
21
USEPA
WATER QUALITY CRITERIA AND STANDARDS PROGRAM
Compilation of National Recommended Water Quality
Criteria and EPA's Process for Deriving New and
Revised Criteria
22
Terrestrial Toxicity Tests

• Direct exposure of test biota to media samples
  from a site
• Indirect exposure to filtered water exposed to
  soil or sediments samples
• Exposure to leachates from a site
• Controlled exposure to a specific contaminant
  using soil from the site

23
Terrestrial Toxicity Tests

• Test biota
• soil microbes and fungi - critical role in C, N,
  S, P cycling, plus production of SOM and other
  organics
• invertebrates (earthworms and insects) provide
  essential ecosystem functions
• These tests are fast, simple and relatively
  inexpensive, with relevant results to evaluate
  effects on ecosystem biogeochemical functions

24
Terrestrial Toxicity Tests

• Vertebrates
• amphibian survival, growth and reproductive
  success
• avian and small mammal reproductive success and
  body burden
• Feeding studies (small mammal and avian toxicity
  tests) are useful to determine potential uptake
  and transfer within the food web - potential
  human exposure route
• Standard protocols have been derived from
  veterinary studies and FDA methods, but many are
  still under development
• Longer than invertebrate tests

25
(No Transcript)
26
Terrestrial Toxicity Tests

• Vegetation
• mostly crops
• primary endpoints are
• survival seed germination test
• growth seedling growth rate and root elongation
  test
• reproduction success vascular plant toxicity
• photosynthesis rates chlorophyll fluorescence
  assay
• can be applied in lab or in the field
• nutrient,water and light limitations can
  complicate analysis of results
• longer term studies

27
(No Transcript)
28
Field Assessments

• Field surveys link chemical analyses and toxicity
  tests with actual effects
• Provide information on extent and patterns of
  contamination
• Indicate presence of sensitive plants or animals
• At larger scale provide info on structure,
  function and dynamics of populations

29
(No Transcript)
30
Field Assessments

• Survey of some or all the populations in the
  aquatic or terrestrial community
• Community structure and/or function are assessed

31
Field Assessments
32
(No Transcript)
33
Field Assessments

• Remote sensing methods
• current resolution may be at 10m or less
  depending on quality of satellite data
• Ground-truthing direct observation
• Long-term monitoring
• Population surveys

34
Biomarkers

• Biological measure of an organisms response to a
  contaminant
• Analyze biological tissues, fluids or cells to
  determine if affected by pollution
• Integrates temporal exposure and multiple
  exposure pathways
• Evaluates pollutant and by-products

35
(No Transcript)
36
Bioaccumulation

• Evaluate net accumulation of chemical in organism
  through ingestion of water or food containing the
  chemical
• Measures difference between rate of ingestion and
  rate of excretion
• Particularly useful for highly accumulating
  chemicals
• metals
• PCBs, some pesticides

37
(No Transcript)
38
Micro and Mesocosm

• Controlled experiments in lab or field to study
  changes at any level
• population
• community
• ecosystem
• Microcosm are small studies, usually in lab
• Mesocosm are large, containing many species,
  usually outdoors

39
Micro and Mesocosm

• Advantages of microcosm studies
• Better than single-species studies
• More space efficient
• Easier to maintain controlled conditions
• Replication and standardization easier
• Low chance of contaminating the environment

40
Micro and Mesocosm

• Issues with Microcosm
• Cant simulate certain processes (e.g. acid
  deposition from environment)
• small population sizes gt extinctions?
• Extrapolation of results
• May leave out a critical and/or sensitive
  component of ecosystem

41
Ecological Risk Assessment

• Problem Formulation
• Gather info, including data, about the problem
• Define assessment endpoints
• Develop a conceptual model
• Plan the analysis phase

42
(No Transcript)
43

• Critically evaluate others data
• How was it gathered or generated?
• Was it well-performed?
• Do the data relate to the concern?

44

• Characterizing exposure
• one part of the overall analysis phase
• End product is an exposure profile outlining
  the types and amounts and circumstances of likely
  exposure.

45
(No Transcript)
46

• Characterizing Ecological effects
• Mainly what is todays subject
• Correlation is not necessarily causality!

47
The Next Wave ToxCast

• EPAs new program for screening toxic chemicals
  using HTS technology
• http//www.epa.gov/ncct/toxcast/index.html
• Initially, pesticides with many endpoints
• Zebra fish development among assays
• Large datasets, aimed at predictive capabilities
  in toxicity assessment

48
Summary

• Methods for assessing effect vary from
• single chemical/single species
• short-term to multiple stressors
• ecosystem/long-term
• Ability to relate cause and effect varies
  accordingly (easier for simpler system)
• Need studies at all scales (temporal and spatial)
  to have better understanding
• Be critical of a standard developed with just one
  methodology!