# Comments of General Motors Corporation on EPA's Draft Framework for Application of the TEQ Methodology for PCDDs/PCDFs and PCBs in Ecological Risk Assessment

## Introduction

This document presents the comments of General Motors Corporation (GM)
on EPA's June 2003 External Review Draft Framework for Application of
the Toxicity Equivalence Methodology for Polychlorinated Dioxins,
Furans, and Biphenyls in Ecological Risk Assessment ("Draft Framework").

GM has reviewed and supports the comments of the PCB Panel of the
American Chemistry Council and the Utilities Solid Waste Activities
Group ("PCB Panel comments"). In several instances, GM refers to these
comments. GM's concerns regarding the Draft Framework document are
primarily focused on EPA's conclusions that assessments of PCBs
conducted using the TEQ approach are "more accurate" and "more certain"
than assessments conducted using the total PCB approach (Draft
Framework, page 71). GM is concerned that these conclusions will be
misinterpreted to mean that the TEQ approach[^1] rather than a total PCB
approach should be used to assess ecological risks at [all]{.underline}
sites where PCBs are present.

GM believes that, whereas the TEQ approach may be an appropriate and
useful approach for ecological risk assessments of PCDDs and PCDFs (or
mixtures of PCBs with substantial amounts of PCDDs and PCDFs), the TEQ
approach should not be the default approach nor should it take the place
of the total PCB approach for assessing ecological risks at all sites
where PCBs are present. The total PCB approach has been used extensively
for evaluating human health and ecological risks and guiding remedial
decisions at PCB sites for many years. The total PCB approach is
environmentally protective and scientifically defensible and is grounded
in well-established and proven protocols. Furthermore, while this
Framework is not policy, EPA has issued numerous guidance documents and
regulations describing and directing the use of the total PCB approach.
Therefore, the Draft Framework should clearly state that the total PCB
approach is still acceptable, especially at sites where the release
being investigated is principally from PCBs.

The Draft Framework does not present the types of analyses required to
evaluate and determine whether one approach is more accurate or more
certain than the other. These types of conclusions need to be supported
by quantitative uncertainty analyses. Moreover, the Draft Framework
fails to consider either the costs associated with changing the way PCBs
are assessed or the potential far-reaching implications that this
recommendation may have on other programs designed to address the
environmental impacts of PCBs. Considering the potential implications of
EPA recommending a TEQ approach rather than, or in conjunction with, a
total PCBs approach, EPA should undertake a complete evaluation of the
merits and limitations of the two approaches, including a rigorous
cost-benefit analysis.

## Comments

### 1) EPA needs to conduct a cost/benefit analysis associated with changing from a total PCB approach to a TEQ approach for assessing ecological risks. 

Implementation of a TEQ approach for evaluating ecological risk of PCBs
will result in much higher costs to the regulated community. As
discussed in the PCB Panel comments, application of a TEQ approach at
PCB sites appears to offer limited advantages and does not necessarily
contribute to better understanding of the problem or better
decision-making ability than use of a total PCB approach. The increased
costs of a TEQ approach for PCB sites is therefore not justified.

Implementation of a TEQ approach will result in increased costs
associated with the following activities:

-   Laboratory analyses, data verification, validation, and management

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-   Ecological risk assessment, including

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-   Transport and fate analysis

-   Exposure modeling

-   Risk Characterization

-   Uncertainty analysis.

Ecological risk assessment for total PCBs currently relies primarily on
analyses of environmental media such as soil, sediment, water, and biota
using EPA method SW-846 8082. These analyses typically cost \$75-110 per
sample (depending on laboratory, and sample preparation, cleanup, etc.).
By contrast, analysis of these same samples for the 12 congeners for
which there are WHO TEFs (the most commonly analyzed congeners) using
EPA method 1668 typically cost \$700-\$1,000, or approximately 10 times
the cost of the existing method SW-846 8082. Ecological risk assessment
of PCBs at typical sites routinely involves collection and analysis of
100 to 300 samples for total PCBs analyses. Investigation and cleanup at
PCB sites, including sites where GM has participated, can require the
collection and analysis of thousands of PCB samples. Based on the per
sample cost estimates provided above, the cost associated with total PCB
analysis of 100 -- 300 samples would be from \$7,500 to \$33,000. In
contrast, if the same number of samples were analyzed for PCB congener
analyses, costs would be between \$70,000 and \$300,000. At sites
involving thousands of samples, the cost differences could approach
millions of dollars for sample analyses alone. In addition, the data
validation process of dioxin-like substances is more rigorous than for
total PCBs and is likely to result in higher costs associated with data
verification, validation, and management. For example, U.S. EPA (2002)
defines a 19-step data validation process for dioxins/furans. Given that
resources are limited at many sites (including EPA sites), switching to
a congener-based approach could result in cutbacks to other aspects of
the investigation, such as fewer samples being collected.

In addition to increased analytical costs, adoption of a TEQ approach
for PCBs will also require a substantial increase in the level of effort
at several stages of the risk assessment process. For example, use of a
TEQ approach for the assessment would involve evaluating bioaccumulation
and exposure for multiple compounds (i.e., congeners) whereas the total
PCB approach involves only a single compound mixture. A similar increase
in effort would be associated with fate and transport modeling. This
fact was partially acknowledged by workshop participants (EPA 2001). For
example, EPA (2001; page 8, item 11) acknowledges that exposure
assessments under the TEQ approach may require more information and
resources " Because physical, chemical, and biological properties vary
among the individual dioxin, furan, and PCB compound" and that "Fate and
transport models used to support the exposure assessment will need to
account for individual compounds through the various modeled
components." Cost increases associated with the increased level of
effort for congener-specific bioaccumulation, exposure, and fate and
transport modeling are more difficult to define, but GM estimates that
implementation of a TEQ approach could easily double the costs required
to evaluate PCBs in an ecological risk assessment. Despite the
workgroup's acknowledgment of these increased costs, EPA has failed to
adequately evaluate the increased costs associated with implementing the
TEQ approach. These costs need to be explicitly acknowledged and
quantified in a formal cost/benefit analysis.

Finally, it unlikely that the handful of commercial analytical
laboratories that currently offer high resolution PCB congener analysis
(e.g., EPA Method 1668\[a\]) could handle the demand if all PCB analyses
for ecological risk assessments were required to be on a
congener-specific basis. In addition to different, more expensive
equipment, congener specific analyses requires specialized training.
Backlogs would cause delays in remediation investigations, drive up
analytical costs, and threaten the environmental benefit derived by more
rapid cleanup of PCB-contaminated sites.

### 2) Framework may be viewed as \"policy\", but lacks typical safeguards/reviews of rulemaking

The framework document states in its disclaimer that "This document is a
draft for external review purposes only and does not constitute U.S.
Environmental Protection Agency Policy". The document also states at
page *vi* that the "framework is not a regulation nor is it intended to
substitute for federal regulations". Despite this disclaimer and caveat,
it must be recognized that the framework document will be cited as EPA
position, and will serve as the basis for decision-making and policy by
regulatory agencies at the state and regional level. Although the TEQ
approach may be appropriate at complex sites involving PCDDs, PCDFs, and
PCBs, it does not represent a better or replacement approach for total
PCBs at all sites. The TEQ approach is still an active area of research
and some of the assumptions are still in the process of being validated.
For example, the National Toxicology Program is currently conducting
research to test some of the assumptions inherent in a TEQ approach.

There is also a high likelihood that, once finalized, the framework will
be used in applications beyond strict ecological risk assessments and by
a wide range of both federal and state agencies. In fact, the workgroup
seems to encourage such an outcome in its discussion of "next steps" (in
the Workshop report at page 19) by suggesting that the framework "would
be useful, ***in the context of ecological risk assessments*** (emphasis
added), to multiple programs engaged in pollution prevention activities
such as water quality standards and NPDES/SPDES permits, planning
activities such as Section 303(d) list generation, total maximum daily
loads (TMDLs), wasteload and load allocations, and remediation
activities such as CERCLA cleanups and Natural Resource Damage
Assessments (NRDAs) by natural resource trustees". This intent is
reinforced in one of the case studies evaluated by EPA (2001) which is a
problem formulation developed for a prospective ecological risk
assessment in support of a TEQ TMDL determination for a hypothetical
paper mill.

Thus, although EPA may not intend the framework to be used as guidance
or regulation, it is very likely that it will in fact be applied as
guidance and policy in practice. There are two far-reaching implications
of this outcome:

-   The framework will be implemented as guidance and policy even though
    it was not subjected to many of the public review and accountability
    requirements of the federal rulemaking process

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-   The framework will be applied to regulatory programs (e.g., Clean
    Water Act) without adequate evaluation of practical implications and
    costs.

When EPA revises the draft framework document, a very clear description
of applications not evaluated in this document should be included.

### 3) Use of TEQ approach for assessment of PCBs does not appear to result in better or more protective risk conclusions than the total PCB approach

Review of ecological risk assessments for PCBs conducted using both the
TEQ and total PCB approaches indicates that both approaches provide
essentially the same answer (see ACC and USWAG comments \[PCB Panel and
USWAG 2003\] for detailed discussion). If anything, the total PCB
approach appears to provide a more protective risk estimate than the TEQ
approach at PCB-dominated sites[^2]. These results are consistent with
data on the weathering of PCBs in the environment that suggest that
weathering tends to result in PCB mixtures that have lower TEQ potency
than Aroclor 1254, which is the basis for most of the toxicity
thresholds used in total PCB approach. Collectively, these data indicate
that, for many sites, use of total PCB is protective and adequate, and
inclusion of the TEQ approach offers very little additional information.
Moreover, these data suggest that although the total PCB approach may
overestimate risks, it is unlikely to result in an underestimate of
ecological risks at PCB-dominated sites.

Another issue identified in the PCB Panel comments that GM believes
warrants discussion in the revised framework document is the fact that
cleanup levels at PCB sites evaluated using the TEQ approach are still
expressed in terms of total PCBs. It is unclear how the purported
benefits of a TEQ approach (e.g., increased accuracy and certainty) are
retained if the results of the assessment are converted back to total
PCBs to facilitate the actual cleanup.

GM believes that it is inappropriate to make broad, definitive
conclusions about the adequacy of the two approaches for ecological risk
assessment. The decision to use a TEQ or total PCB approach should be
based on site-specific information. It would be more helpful and
instructive if EPA conducted a thorough review and analysis of the
technical merits and limitations of both approaches and clearly
identified scenarios where a total PCB approach is adequate, and more
complex scenarios where a TEQ approach may be warranted.

### 4) EPA must conduct a quantitative uncertainty analysis to support its conclusions about the relative certainty and accuracy of the total PCB and TEQ approaches. 

Although EPA identifies many of the uncertainties associated with the
TEQ approach, the discussion is limited and qualitative. The discussion
regarding uncertainties associated with assumptions inherent in the TEQ
(e.g., additivity, representativeness of individual TEFs) are
particularly superficial and incomplete. For the total PCB approach, EPA
makes only passing reference to uncertainties associated with analytical
methods and weathering. Nevertheless, EPA makes the conclusion that the
TEQ approach is "more accurate" and "more certain" for PCB assessments
than the total PCB approach. EPA should either conduct a more thorough
and quantitative uncertainty analysis for the two approaches to support
these conclusions, or remove this language from the Draft Framework.

## Summary

GM acknowledges and appreciates that there is a considerable effort in
the scientific community to increase the sophistication, reliability,
and accuracy of ecological risk assessments for PCBs. GM also
acknowledges that the TEQ approach holds promise for improving
ecological risk assessments for PCBs. However, GM believes that the
information generated and presented by EPA in the Framework fails to
support EPA's conclusions that assessments of PCBs conducted using the
TEQ approach are "more accurate" and "more certain" than assessments
conducted using the total PCB approach. Whereas the TEQ approach
involves a more accurate and detailed description of the precise PCB
mixture present, it does not necessarily lead to a better or different
risk conclusion. Moreover, it appears that at the end of the assessment,
cleanup goals are still expressed on a total PCB basis (i.e., although
we may now be able to measure using a micrometer, we are still cutting
using a chainsaw). GM's main concern is that the framework document will
be interpreted by some as an endorsement of the TEQ approach over the
total PCB approach at all sites where there are PCBs. To avoid this
misinterpretation, EPA must clarify that the TEQ approach is best suited
for sites where PCBs as well as PCDDs and PCDFs are present at
concentrations sufficient to warrant risk assessment and that the total
PCB approach continues to be an acceptable approach for evaluating risks
at sites where PCBs are considered the primary concern rather than
mixtures of PCBs with PCDDs and PCDFs.

GM is also very concerned about the increased costs that would result
from a requirement to perform TEQ-based risk assessments for PCBs.
Increased analytical costs could add hundreds of thousands of dollars to
the price tag of an investigation at a "typical" site and increased
effort for risk assessment tasks could double the cost of an ecological
risk assessment. These costs are dramatically magnified at PCB sites
where thousands of samples may be required. EPA needs to conduct a
thorough cost-benefit analysis to weigh the economic impact of adopting
the TEQ approach at PCB sites against the benefits.

Finally, GM is also concerned that concepts presented in the Draft
Framework may be applied to other regulatory programs not primarily
targeted in the Draft Framework document (e.g., NPDES, TMDL, and NRDA).
The ramifications of the use of the congener-specific TEQ approach for
PCBs are far reaching. EPA needs to be careful and deliberate in how it
goes about implementing such an approach, giving consideration to how
all areas of environmental policy will be affected.

## References

Comments of the Polychlorinated Biphenyls (PCB) Panel of the American
Chemistry Council and the Utilities Solid Waste Activities Group on
EPA's Draft Framework for Application of the TEQ Methodology for PCDD/Fs
and PCBs in Ecological Risk Assessment. October 29, 2003

U.S. EPA. 2000. Exposure and human health reassessment of
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds
(External Review Draft). National Center for Environmental Assessment,
Office of Research and Development, Washington, DC;
EPA/600/P00/001B(a-f).

USEPA. 2001. Workshop report on the application of 2,3,7,8-TCDD toxicity
equivalence factors to fish and wildlife.

U.S. EPA. 2002. FinalNational Functional Guidelines for chlorinated
dioxin/furan data review. U.S. EPA Analytical Operations/Data Quality
Center (AOC). OSWER 9240.1-37 EPA 540-R-02-003.

[^1]: Although EPA states in the Draft Framework that the document does
    not constitute EPA policy and it is not a regulation, these types of
    documents frequently serve as the basis for decision-making and
    policy by regulatory agencies at the state and regional level.

[^2]: The results of several ecological risk assessments conducted using
    both a TEQ approach and total PCB approach are reviewed in the
    comments submitted by the PCB Panel of ACC and USWAG.