	United States

Environmental Protection Agency	Office of Water4304T	  SEQ CHAPTER \h \r
1 EPA-822-F-08-002

June 2008

	Methodology for Deriving Ambient Water Quality Criteria  for the
Protection of Human Health (2000)

Draft Technical Support Document, 

Volume 3: Development of Site-Specific Bioaccumulation Factors

EPA has released for scientific views a draft of a third technical
support document to accompany the Methodology for Deriving Ambient Water
Quality Criteria for the Protection of Human Health, published in 2000.
The Draft Technical Support Document, Volume 3: Development of
Site-specific Bioaccumulation Factors (Site-specific TSD”) contains
technical details on how states and tribes may develop site-specific
bioaccumulation factors (BAFs) for use in deriving site-specific ambient
water quality criteria for protecting human health.  The first two
technical support documents are entitled Technical Support Document,
Volume 1: Risk Assessment and Technical Support Document, Volume 2:
Development of National Bioaccumulation Factors (National TSD).

Background

Aquatic organisms can accumulate chemicals in their bodies when they are
exposed to these chemicals through water, their diet, and sediment. This
process is called bioaccumulation. The extent of bioaccumulation by
aquatic organisms varies widely depending on the chemical and the
species, but it can be extremely high for some highly persistent and
lipid-soluble chemicals. For such highly bioaccumulative chemicals,
concentrations in aquatic organisms may pose unacceptable human health
risks from eating fish and shellfish even when concentrations in water
are too low to cause unacceptable health risks from drinking the water. 

In order to prevent harmful exposures to chemicals in water through
eating contaminated fish and shellfish, Clean Water Act Section 304(a)
national water quality criteria recommendations (“304(a) criteria”)
for protecting human health must address chemical bioaccumulation in
aquatic organisms.  Technical Support Document, Volume 2: Development of
National Bioaccumulation Factors (“National TSD”) describes how to
calculate national bioaccumulation factors for use in 304(a) criteria.  

In developing the National TSD, EPA envisioned the development of a
second technical support document to address bioaccumulation and provide
guidance on how to modify the national bioaccumulation factors (BAFs) to
derive BAFs that are more representative of the bioaccumulation
potential at a given location (i.e., site-specific BAFs).  The draft
Site-specific TSD provides guidance on different approaches that
investigators can take to develop site-specific BAFs, and the factors
that should be considered when selecting an approach for a given
situation.  Neither of the bioaccumulation TSDs should be used alone to
derive BAFs, but rather should be used in conjunction with the 2000
Human Health Methodology.  The intended audience for the draft
Site-specific TSD includes state and tribal water quality staff
scientists or risk assessors (“investigators”) who are responsible
for deriving state or tribal water quality standards, stakeholders
interested in developing site-specific BAFs, and other users interested
in site-specific bioaccumulation issues for other applications.  

About this Technical Support Document

In 2000, EPA published the Methodology for Deriving Ambient Water
Quality Criteria for the Protection of Human Health ("2000 Human Health
Methodology") that updated and revised the existing 1980 Ambient Water
Quality Criteria National Guidelines. The 2000 Human Health Methodology
incorporates scientific advancements made over the past two decades in
chemical risk assessment, exposure assessment, and bioaccumulation. 

EPA developed detailed procedures and guidelines described in the 2000
Human Health Methodology for estimating BAF values for use in deriving
or revising ambient water quality criteria. The National TSD discusses
the technical basis for developing national BAFs, the underlying
assumptions and uncertainties inherent to the approach, and applying the
bioaccumulation component of the 2000 Human Health Methodology. The
draft Site-specific TSD expands on the information presented in the
National TSD by providing users specific information on how to calculate
site-specific BAFs for use in modifying the national 304(a) criteria. 
The draft Site-specific TSD presents methods for states, tribes and
other interested parties to calculate BAFs that are specific to their
site.  The goal in deriving site-specific BAFs is to determine the most
accurate estimates of bioaccumulation feasible for each site.  The draft
Site-specific TSD follows the same methodology presented in National
TSD.  

Technical Information

Using the 2000 Human Health Methodology, water quality criteria are
derived using a bioaccumulation factor to reflect the uptake and
retention of a chemical by fish and shellfish from all sources (e.g.,
water, food, sediment).  The National TSD and the draft Site-Specific
TSD include a framework for selecting the appropriate procedure for
deriving a BAF that is based on chemical properties, biological activity
and scientific information.  The draft Site-Specific TSD expands on this
information by providing information on sampling and statistical
techniques, modification of existing national BAFs for site-specific
application, and empirical calculations of site-specific BAFs.  

How do I get a copy of the draft technical support document?

EPA requests scientific views on all aspects of the draft Site-Specific
TSD, including the soundness of the technical approaches described in
the document, the usefulness of the document for states and tribes in
calculating site-specific BAFs, and the document’s clarity of
presentation.  You can get copies of "Methodology for Deriving Ambient
Water Quality Criteria for the Protection of Human Health, Draft
Technical Support Document, Volume 3: Development of Site-Specific
Bioaccumulation Factors" (EPA-822-B-08-001) by   HYPERLINK
"http://www.epa.gov/waterscience/criteria/humanhealth/method/" 
downloading the document from EPA's web site  at
www.epa.gov/waterscience/criteria/humanhealth/method/index.html.

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