California Sediment Quality Objectives Bioaccumulation Methods

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California Sediment Quality Objectives
Bioaccumulation Methods
A Presentation to the SQO Scientific Steering
Committee July 27, 2005
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Presentation Summary

• Background and Conceptual Model
• Three Lines of Evidence
• Technical Issues With Each Line of Evidence

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Conceptual Model
Exposure Assessment
Effects Thresholds For Humans
Effects Thresholds For Wildlife/Fish
Chemical uptake via diet, respiration
Effects Assessment
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Multiple Lines of Evidence Approach
Exposure Assessment
Effects Thresholds For Humans
Effects Thresholds For Wildlife/Fish
Chemical uptake via diet, respiration
Effects Assessment
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Indirect Effects Multiple Lines of Evidence
(MLOE)
Human Lines of Evidence
Fish and Wildlife Lines of Evidence
Fish Concentration
Fish Concentration
Laboratory Bioaccumulation Concentration
Laboratory Bioaccumulation Concentration
Sediment Concentration
Sediment Concentration
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1. Fish Line of Evidence

• Tissue contaminant concentration in field
  captured fish
• Assesses beneficial use impairment.
• Does not directly implicate sediments
• Other sources (water column, watershed loading)
• Fish movement

Fish Concentration
Laboratory Bioaccumulation Concentration
Sediment Concentration
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2. Sediment Line of Evidence

• Contaminant concentrations in sediments
• Assess whether sediments are a potential source.
• Does not assess variations in bioavailability
• Physical parameters, e.g., soot carbon, paint
  chips.

Fish Concentration
Laboratory Bioaccumulation Concentration
Sediment Concentration
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3. Bioaccumulation Line of Evidence

• Contaminant concentrations in laboratory
  bioaccumulation tests
• Are sediment contaminants bioavailable?
• Has limitations
• Difficulty achieving equilibrium
• Laboratory extrapolation

Fish Concentration
Laboratory Bioaccumulation Concentration
Sediment Concentration
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Technical Issues

• Fish Line of Evidence
• What are appropriate target species?
• What assumptions to use in calculating tissue
  thresholds?
• Consumption rate
• Risk level
• Bioaccumulation Line of Evidence
• What are the most appropriate tests?
• What are appropriate thresholds?
• Sediment Chemistry Line of Evidence
• How address fish movement?
• How translate from fish threshold to sediment
  threshold?

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Technical Issues

• Fish Line of Evidence
• What are appropriate target species?
• What assumptions to use in calculating tissue
  thresholds?
• Consumption rate
• Risk level
• Bioaccumulation Line of Evidence
• What are the most appropriate tests?
• What are appropriate thresholds?
• Sediment Chemistry Line of Evidence
• How address fish movement?
• How translate from fish threshold to sediment
  threshold?

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Target Species
Species previously monitored in CA Bays and
Estuaries with sediment linkage in adult
lifestyle
Arrow Goby Black Surfperch California
Corbina California Halibut California
Killifish Dwarf Surfperch English Sole Leopard
Shark Longfin Sanddab Pacific Sanddab Pacific
Staghorn Sculpin
Saddleback Sculpin Shiner Surfperch Slender
Sole Speckled Sanddab Spotted Sandbass Starry
Flounder Striped Mullet Walleye Surfperch White
Croaker White Surfperch Yellowfin Goby
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Target Species
Prey For Humans and Wildlife
Limited Variation in Diet or Home Range
Sediment Linkage
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Target Species - Sediment Linkage
Bold indicates significant r2 value and positive
slope
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Target Species - Sediment Linkage

• Evaluate different species using mechanistic
  model simulations
• Gobas model parameterized for San Francisco Bay
• Includes dietary and respiratory uptake
• Run simulations setting water vs. sediment input
  to zero to estimate relative influence of
  waterborne vs. sediment contaminants
• Approach may be used locally wherever food web
  data are available

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Target Species - Sediment Linkage
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Technical Issues

• Fish Line of Evidence
• What are appropriate target species?
• What assumptions to use in calculating tissue
  thresholds?
• Consumption rate
• Risk level
• Bioaccumulation Line of Evidence
• What are the most appropriate tests?
• What are appropriate thresholds?
• Sediment Chemistry Line of Evidence
• How address fish movement?
• How translate from fish threshold to sediment
  threshold?

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Fish Tissue Thresholds For Protecting Humans

• Standard risk assessment approach
• Threshold Fish Concentration
• Function of (Toxicity Reference Value,
  Dose, Body Size)
• Threshold choice is in large part a policy
  decision
• Target population to protect
• (e.g., consumption rate)
• Allowable Risk Level

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Fish Tissue Thresholds For Protecting Humans

• Comparison of thresholds using different
  assumptions
• Federal or state recommended policies
• Two additional thresholds represented more or
  less
• conservative assumptions

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Fish Tissue Thresholds For Protecting Humans
Thresholds vary greatly depending on assumptions
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Fish Tissue Thresholds For Protecting Humans
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Exceedances Using Different Thresholds
Effects thresholds vs. organic contaminant
concentrations in three sportfish species (Shiner
Surfperch, California Halibut, and White Croaker)

• Human thresholds generally lower - will drive the
  SQO
• DDT is an exception
• Chlordane generally does not exceed thresholds

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Bioaccumulation Work Group
Appropriate Assumptions for Thresholds
Also Many BTAG Members
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Fish Tissue Thresholds For Protecting Wildlife

• General approach
• Threshold Fish Concentration
• Function of (Toxicity Reference Value,
  Dose, Body Size)
• Dose based on body mass allometry equation
• Statewide based on generic species classes
• Local regulators refine with site-specific data
  for individual water bodies

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Fish Tissue Thresholds For Protecting Wildlife
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Fish Tissue Thresholds For Protecting Wildlife

• Toxicity Reference Values
• DDTs, PCBs, Hg - Using USEPA Region 9 BTAG
  TRV-Low
• Dieldrin - USEPA ECO-SSL values
• Chlordane - no consensus values available
• Mammals - Khasawinah and Grutsch 1989
• Birds - Stickel et al. 1983
• Recall that chlordanes do not exceed thresholds
  for any fish (N 192)

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Fish Tissue Thresholds For Protecting Wildlife

• Avian results lower
• Small animals lower

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Exceedances Using Different Thresholds
Comparison of organic contaminant concentrations
in three sportfish species (Shiner Surfperch,
California Halibut, and White Croaker) to
wildlife and human effect thresholds

• Among wildlife, small birds would drive the SQO
  for
• PCBs and DDTs

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Technical Issues

• Fish Line of Evidence
• What are appropriate target species?
• What assumptions to use in calculating tissue
  thresholds?
• Consumption rate
• Risk level
• Bioaccumulation Line of Evidence
• What are the most appropriate tests?
• What are appropriate thresholds?
• Sediment Chemistry Line of Evidence
• How address fish movement?
• How translate from fish threshold to sediment
  threshold?

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Methods GuidanceTarget Species - Lab Test
Organisms

• Species with existing data in SQO database

• Macoma nasuta is a good species for Laboratory
• Bioaccumulation test
• -Recommended for bed sediment testing (EPA
  guidance)
• -Deposit feeder with high contaminant tolerance
• -Large California database available

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Target Species - Macoma nasuta
Contaminant SF Central Bay San Pedro Bay Tomales Bay San Diego Bay
Total DDTs n 137 n 77 n 12 ND
R2 0.56 0.13 0.12
Total PCBs n 63 ND ND n 14
R2 0.39 0.93
Total HPAHs n 137 n 77 n 11 n 14
R2 0.19 0.39 0.52 0.80
Chlordanes n 137 n 78 n 12 ND
R2 0.64 0.34 0.27
Summary of regression analysis of summed
contaminant concentrations in sediment and Macoma
nasuta tissue. significant
linear relationship (plt0.05) ND No Data
Available
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San Diego
San Pedro
SF
Tomales
Linear (SF)
Bivalve Tissue Concentration (log x1, ug/kg, dry
wt.)
Linear (San Diego)
Linear (Tomales)
Linear (San Pedro)
2
2.5
3
3.5
4
4.5
5
5.5
6
Sediment Concentration (log x1, ug/kg, dry wt.)
Macoma nasuta tissue data indicate different
results for different water bodies. BSAFs vary
among waterbodies
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Technical Issues

• Fish Line of Evidence
• What are appropriate target species?
• What assumptions to use in calculating tissue
  thresholds?
• Consumption rate
• Risk level
• Bioaccumulation Line of Evidence
• What are the most appropriate tests?
• What are appropriate thresholds?
• Sediment Chemistry Line of Evidence
• How address fish movement?
• How translate from fish threshold to sediment
  threshold?

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Bioaccumulation Line of EvidenceMethods of
Evaluation
B

• How establish threshold with this line of
  evidence? Potential methods
• Test for any bioavailability
• Organism tissue concentrations above
  concentrations in control organisms
• Test for bioaccumulation
• BSAF gt 1
• Test for tissue effects threshold exceedance
• Use test organisms as surrogates for dietary
  exposure to fish, wildlife, and humans
• With 28-day test, must correct for lack of
  equilibrium in short time frame

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Bioaccumulation Line of EvidenceMethods of
Evaluation
B

• 3. Test for tissue effects threshold exceedance
• Correcting for lack of equilibrium in 28 day time
  frame
• More conservative approach multiply laboratory
  results by 4 (USEPA Ocean Disposal Testing Manual
  1991)
• Less conservative approach multiply laboratory
  results by factor between 1 and 3, depending on
  compound Kow (USEPA Inland Testing Manual 1998
  McFarland 1994)
• Use longer time frame e.g., 45 day test (very
  costly)

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Technical Issues
S

• Fish Line of Evidence
• What are appropriate target species?
• What assumptions to use in calculating tissue
  thresholds?
• Consumption rate
• Risk level
• Bioaccumulation Line of Evidence
• What are the most appropriate tests?
• What are appropriate thresholds?
• Sediment Chemistry Line of Evidence
• How address fish movement?
• How translate from fish threshold to sediment
  threshold?

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Fish Movement
S

• Fish have variable home ranges and are often not
  captured where sediment data available.
• Approach
• Fish concentrations compared with sediments in a
  disk centered at each fish sampling location.
• Disk size ranged from 0.5 - 15 km (0.5 km
  increments)
• No a priori assumptions about fish home range

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• Identify best spatial scale to combine fish and
  sediment data.

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• Diagnose spatial association between fish and
  sediment contamination for a given water body.

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Technical Issues

• Fish Line of Evidence
• What are appropriate target species?
• What assumptions to use in calculating tissue
  thresholds?
• Consumption rate
• Risk level
• Bioaccumulation Line of Evidence
• What are the most appropriate tests?
• What are appropriate thresholds?
• Sediment Chemistry Line of Evidence
• How address fish movement?
• How translate from fish threshold to sediment
  threshold?

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Translating From Fish Threshold To Sediment
Threshold
S
Effects Thresholds For Humans
Effects Thresholds For Wildlife/Fish
?
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Translating From Fish Threshold To Sediment
Threshold
S

• Potential Approaches
• BAF and BSAF
• Regression Model
• Mechanistic Model
• Combine 1 and 3

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Focus of Effort

• Non-ionic organic compounds with extensive
  exposure and effects data
• PCBs
• Legacy Pesticides (DDTs, Chlordanes, Dieldrin)

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1. BAF and BSAF

• 1. BSAF Lipid-normalized tissue conc./ organic
  carbon-normalized sediment conc.
• 2. BAF Tissue conc. / sediment conc.
• Both methods use paired samples from multiple
  locations, pooling data from a representative
  range when necessary

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BAF vs. BSAF
100
2
R
0.2541
10
BAF
Tissue DDT (ug/kg)
2
R
0.6585
BSAF
1
1
10
100
1000
0.1
Sediment DDT (ug/kg)
DDTs in San Francisco Bay
Macoma clams vs. sediment
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BAF Example Application

• Using the shiner surfperch dataset from San
  Francisco Bay, calculated the BAF for each sample
  (N 43)
• Determined distribution to be log- normal
• Determined geometric mean BAF and used it to
  backcalculate sediment thresholds from tissue
  thresholds
• Less conservative
• Determined 95 CI to estimate high-end BAF and
  backcalculate low end sediment thresholds
• More conservative

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BAF Example Application

• Example results in three thresholds
• More conservative threshold - 95ile BAF using
• CTR tissue criteria
• Intermediate threshold - GeoMean BAF using CTR
• Less conservative threshold - GeoMean using
• US EPA Screening Value for general population

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2. Regression Modeling
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F
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2. Regression modeling

• Cannot predict well outside data range
• High data requirements
• High uncertainty

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Translating From Fish Threshold To Sediment
Threshold3. Mechanistic Modeling

• Uptake
• Dietary
• Gill

• Loss
• Excretion
• Egestion
• Gill Elimination
• Metabolism

Growth
Chemical properties (e.g., Kow) important
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Mechanistic Model Example Application

• Calculate BAFs for pesticides in San Francisco
  Bay
• Using Gobas (1993) model, as updated by Arnot and
  Gobas (2005)
• Inputs required
• Contaminant Kow
• Quantitative representation of food web structure
• Animal body mass, lipid content, feeding strategy
• Water body chemistry (temperature, DO, TSS)

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White Croaker

• Input food web
• data

Shiner Surfperch
Jacksmelt
Zooplankton
Algae
Amphipods
Grass Shrimp
Mollusks
Polychaete Worms
Sediment
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• Model outputs
• BAFs for modeled
• Species
• Can estimate
• Uncertainty using
• Monte Carlo

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4. Combine BAF/BSAF With Mechanistic Model

• Corroborate mechanistic model results with field
  BAF data
• If results don't fit, reevaluate model
  assumptions, and/or collect more data
• Requires same data as mechanistic model, but also
  requires field data to confirm BAFs
• Contaminant concentrations in water and sediments
• Contaminant concentrations in biota of interest

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• Compare results to
• Sediments
• Biota

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Combined Approach For San Francisco BayPesticides
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Combined Approach For San Francisco BayPCBs
Source Gobas and Arnot, 2005
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Ease of Implementation
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Bioaccumulation MethodsSummary

• Indirect effects relies on MLOE fish tissue
  chemistry, bioaccumulation tests, and sediment
  chemistry
• Fish tissue thresholds are driven by policy
  decisions. Modify assumptions to accommodate
  State decision.
• Bioaccumulation - Macoma nasuta an applicable
  test.
• Sediment contamination - number of methods
  available, depending on time, data, and
  expertise.
• BSAF or BAF
• Mechanistic modeling using Gobas model

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Future Steps

• Develop approach to integrate lines of evidence
• Equal weighting?
• Tiered implementation?
• Continue case studies - Newport Bay
• Develop approaches for other contaminants
• Mercury
• PAHs
• Develop guidance manual

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Contact Information

• Ben Greenfield ben_at_sfei.org
• Mike Connor mikec_at_sfei.org
• www.sfei.org
• Acknowledgements
• Ned Black, Michael Anderson, Laurie Sullivan,
  Katie Zeeman, Robert Brodberg and other members
  of Bioaccumulation Work Group
• Beckye Stanton, Regina Donohue, Julie Yamamoto,
  and othe BTAG members
• Frank Gobas and Jon Arnot, Simon Frasier
  University

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Supplemental Information
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Fish Tissue Thresholds For Protecting Humans

• California Toxics Rule gives explicit guidance as
  to fish tissue risk assessment assumptions in
  developing state water quality objectives
• "EPA assumes 6.5 grams per day of contaminated
  fish and shellfish consumptionfor a 70 kilogram
  person in calculating the criteria.For
  carcinogens, the risk assessments are upper bound
  one in a million (10-6) lifetime risk
  numbers.EPA maintains an electronic database
  which contains the official Agency consensus for
  oral RfD assessments and carcinogenicity
  assessments which is known as the Integrated Risk
  Information System (IRIS)."

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Methods GuidanceTarget Species - Small Home
Range
Total PCBs
Spatial patterns in total PCB concentrations and
stable isotope signatures suggest site fidelity
for shiner perch in the San Francisco Estuary