Tissue Sampling & Analysis PlanTechnical Memorandum on Bioaccumulation ModelingSummary and Discussion

Jennifer Sampson

June 25, 2010

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Discussion Overview

• Tissue Sampling and Analysis Plan

— Objectives of tissue sampling

— Design and rationale

• Technical Memorandum on Bioaccumulation Modeling

— Analysis of area-wide tissue and sediment data

— Literature review

• Goal of this discussion is to assist in your review of these documents

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Tissue Sampling and Analysis Plan

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Objectives of Tissue Sampling

• Human and ecological exposure and risk assessment

— Ingestion exposures for consumers of fish and invertebrates

— Exposures as whole body concentrations for fish and invertebrates

• Development of sediment-tissue relationships to support evaluation of remedial alternatives

— Expand existing datasets to:

» Improve statistical power (with higher sample size)

» Characterize relationship at realistic Site exposures

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Approach to Tissue Sampling

• Gain representation of the range of exposure levels

— Use of “fish collection areas” on the Site, upstream

— Focus on species with small home ranges, close association with sediment

• Expand on existing datasets

— Samples are to be collected as for the TMDL and TDSHS programs

• Address both human health and ecological risk assessment data needs

— E.g., collect both fillet and whole fish tissue

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Overview of Sampling Design

• Fish Collection Areas— Three within the preliminary Site perimeter, one at

upstream background

• Human Health Risk Assessment— Crab edible meat (composites, 5 crabs each)

— Catfish fillet (composites, 3 fish each, skin off)

— Clams (composites to required mass, depurated)

• Ecological Risk Assessment— Clams (Rangia cuneata)

— Whole small fish (Gulf killifish)

— Whole large fish (blue catfish)5

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Tissue Design Summary

Number of Tissue

Collection AreasNumber of Samples Analyzed per Area

Total Number of Samples

Within preliminary Site perimeterCatfish Fillet 3 10 30Whole Catfish 3 3 - 4 10Edible Crab Tissue 3 10 30Small Fish 5 2 10Mollusc 5 5 25

Upstream BackgroundCatfish Fillet 1 10 10Whole Catfish 1 6 6

Edible Crab Tissue 1 10 10Small Fish 2 3 6Mollusc 2 5 10

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Tissue Sampling Areas: Within Preliminary Site Perimeter

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Tissue Sampling Areas: Upstream Background

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Large Fish Collection

• Target species: Blue catfish (300-450 mm)

• Capture methods include set lines, gill nets, hook and line, trawls

• Composite sample consisting of 3 fish

— Fillet (skin on)

— Remainder

• All composites will be single species

• Alternate species are defined in the SAP

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Small Fish Collection

• Target Species: Gulf killifish (50-80 mm)

• Capture methods include beach seines, fish traps, cast nets

• Composite sample consisting of 10 fish

— Whole body

• Bycatch will be used if enough killifish aren’t found

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Bivalve Collection

• Target species: Common rangia

• Capture methods include benthic sediment grab, benthic sledge, shovel/rake

• Clams will be depurated for 24-48 hours prior to processing

• Composite samples

— Number in composite depends on average wet weight to shell length

— All soft tissue and liquids

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Crab Collection

• Target species: Blue crab (125-200 mm)

• Capture methods include: crab traps, trawls

• Composite samples consisting of 3-5 crabs

— Number in composite based average wet weight to shell length

— Muscle tissue only

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Example Tissue Processing Area

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Sample Log-In Procedures

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Species Identification/Confirmation

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Length and Weight Measurements

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Fish Filleting and Dissection

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Upstream as Background

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Upstream as Background: Summary

• Review USEPA 2002 Guidance on Background

— EPA recognizes anthropogenic & natural background

— EPA articulates the relationship between cleanup goals and background

• Uncertainties and data gaps

• Patterns in sediment and source chemistry

• Conceptual framework for bioaccumulation of dioxins and furans

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CERCLA Guidance on Background (EPA 2002)

• Background refers to constituents or locations that are not influenced by releases from a site, and are usually described as naturally occurring or anthropogenic.

• Naturally occurring – substances present in the environment in forms that have not been influenced by human activity.

• Anthropogenic – natural and human-made substances present in the environment as a result of human activities (not specifically related to the CERCLA site in question).

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CERCLA Guidance on Background (EPA 2002)

“The CERCLA program normally does not set cleanup levels below anthropogenic background. The reasons for this approach include cost effectiveness, technical practicability, and the potential for recontamination of remediated areas by surrounding areas with elevated background concentrations. ”

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Upstream Sediments and Sources

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Data Gaps: Upstream Tissue

• Summary statistics for the tissue dataset indicate that more information is necessary

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Data Gaps Include the Upstream Condition

• Available evidence suggests that sediment transport from the impoundments is limited, including upstream transport

— More analysis of upstream transport are planned

• Other dioxin and furan sources occur upstream and regionally, are of interest to the RI/FS, and should be discussed

• Additional information is needed on both sediment and tissue chemistry before upstream can be disqualified as a useful background area

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Technical Memorandum on Bioaccumulation

Modeling

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Bioaccumulation Tech Memo Outline

• Background and Purpose

• Review of Available Modeling Methods

• Analysis of Site-specific Data

• Literature Review

• Conceptual Framework

• Conclusion

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Available Options

• Overly Complex

— PBPK Models

— Food Web Models

• Overly Simple

— Ratios (BSAF, BAF)

• Empirical, Site-specific (MLR)

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systems-biology.com

http://fl.biology.usgs.gov/coastaleco/Tech-Rept-Pinnacles-2002/chapter_2/results_and_discussion/MMS_2002_034_54a.gif

MLR

Modeled Tissue Result

Mea

sure

d Ti

ssue

Dat

a

BSAF

LOG Sediment

LOG

Tis

sue

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Spatial Extent of Tissue Samples

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Analysis Presented in the Tech Memo

• Analysis of Site-specific data yielded generally poor correlations between sediment or water and tissue

— Univariate (tau-b) correlation coefficients <0.58

— Multivariate regressions explained <58 percent of the variation in the tissue data set

— Correlations were strongest for 2,3,7,8-TCDD/F

— Water-tissue and sediment-tissue correlations were not found for most congeners

• Simultaneous review of the literature showed similar patterns to those observed in HSC fish and crab

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Sediment vs. Edible Crab Tissue: tau-b

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Sediment vs. Edible Crab Tissue: MLR

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Results of Literature Review

• Literature indicates that bioaccumulation of dioxins and furans is unlike bioaccumulation of other organic chemicals

— Limits on uptake, especially larger congeners

— Ability to metabolize and excrete dioxins and furans

• Organisms take up 2,3,7,8-TCDD/F more readily than other dioxin and furan compounds, but can also metabolize and excrete them

• Uptake of OCDD is limited, possibly only in the gut

• Dioxins and furans exhibit little to no biomagnification

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At Least Four Metabolic Pathways are Described

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Hu and Bunce 1999

Example of TCDD Metabolism

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Catfish

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Crab

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Tokyo Bay

36Naito et al. (2003)

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Lake Ontario

37Niimi (1996)

San Jacinto

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Memorandum Findings

• Relatively high proportions of 2,3,7,8-TCDD/F can occur in tissue throughout the waterway in the absence of elevated concentrations of these congeners in exposure media (sediment and water)

— A conceptual framework is presented

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Memorandum Findings

• Statistical regression modeling is the most appropriate tool for linking tissue and sediment chemistry

— Empirically based

— Provides a quantitative measure of uncertainty

— Requires minimal assumptions and ancillary data

• Relationships for existing data have low precision

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References Cited

Hu, K., and N.J. Bunce, 1999. Metabolism of polychlorinated dibenzo-p-dioxins and related dioxin-like compounds. J. Toxicol. Environ. Health, Part B 2(2):183–210.

Naito, W., J. Jin, Y-S. Kang, M. Yamamuro, S. Masunaga, and J. Nakanishi, 2003. Dynamics of PCDDs/DFs and coplanar-PCBs in an aquatic food chain of Tokyo Bay. Chemosphere 53:347–362.

Niimi, A.J., 1996. Evaluation of PCBs and PCDD/Fs retention by aquatic organisms. Sci. Tot. Environ. 192:123-150.

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