United States
Environmental Protection
Agency
Office of Research and
Development
Washington DC 20460
EPA/630/R-94/006
November 1994
Report on the
Technical Review
Workshop on the
Reference Dose for
Aroclor 1016
RISK ASSESSMENT FORUM
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EPA/630/R-94AJ06
November 1994
REPORT ON THE TECHNICAL REVIEW WORKSHOP ON
THE REFERENCE DOSE FOR AROCLOR 1016
Prepared by:
Eastern Research Group, Inc.
110 Hartwell Avenue
Lexington, MA 02173
EPA Contract No. 68-CO-0068
September 1994
Risk Assessment Foium
U.S. Environmental Protection Agency
Washington, DC
Printed on Recycled Paper
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NOTICE
Mention of trade names or commercial products does not constitute endorsement or
recommendation for use. Statements are the individual views of each workshop participant; none
of the statements in this report represent analyses or positions of the Risk Assessment Forum or the
U.S. Environmental Protection Agency (EPA).
This report was prepared by Eastern Research Group, Inc. (ERG), an EPA contractor, as
a general record of discussions during the Technical Review Workshop on the Reference Dose for
Aroclor 1016. As requested by EPA, this report captures the main points and highlights of
discussions held during workshop sessions and includes brief summaries prepared by the workshop
chairs of the three technical issues discussed. The report is not a complete record of all details
discussed, nor does it embellish, interpret, or enlarge upon matters that were incomplete or unclear.
In particular, each of the three technical issue summaries was prepared at the workshop by the
individual chairs based on the panel's discussions during the workshop. Thus, there may be slight
differences between the chairs'recommendations.
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CONTENTS
Foreword v
SECTION ONE—OVERVIEW ,. 1-1
General Summary . .... .. 1-1
Background of Reference Dose for Aroclor 1016 .. 1-4
SECTION TWO—CHAIRPERSON'S SUMMARY OF THE WORKSHOP .. ... 2-1
Dr. MariGolub
SECTION THREE—REVIEW GROUP SUMMARIES 3-1
Critical Effects Issues 3-1
Dr. Thomas Burbacher
Exposure Issues 3-12
Dr. Nancy Kim
Uncertainty Factors Issues 3-17
Dr. Man Golub
SECTION FOUR—HIGHLIGHTS FROM TECHNICAL REVIEWERS' PRELIMINARY
COMMENTS . 4-1
SECTION FIVE—REFERENCES 5-1
APPENDICES A-E: EPA PREMEETING MATERIALS
APPENDIX A. Final Participant List A-l
APPENDDC B. Agenda B-l
APPENDIX C. Charge to Reviewers C-l
x,
APPENDIX D. Background Information for Technical Reviewers D-l
APPENDIX E. Premeeting Comments E-l
APPENDICES F-G: OBSERVERS AND OBSERVER MATERIALS
APPENDIX F. Final Observer List F-l
APPENDK G. Observer Comments G-l
iii
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FOREWORD
This report includes information and materials from a technical review workshop organized
by the U.S. Environmental Protection Agency's (EPA's) Risk Assessment Forum for EPA*s
Reference Dose/Reference Concentration (RfD/RfC) Work Group. The meeting was held in
Washington, DC, at the Barcelo Washington Hotel on May 24-25,1994. The subject of the technical
review was the Integrated Risk Information System (IRIS) RfD entry for Aroclor 1016, a
polychlorinated biphenyl (PCB). The expert technical review panel was convened to independently
evaluate whether the RfD for Aroclor 1016 is based on a scientifically responsible analysis that
represents full consideration of the available data and clear articulation of that analysis in the IRIS
RfD entry. .. ,
Notice of the workshop was published in the Federal Register on May 5,1994 (59 FR 23202).
The notice invited members of the public to attend the workshop as observers and provided logistical
information to enable observers to preregister. Observers attending the workshop included
representatives from federal government, industry, academia, consulting firms, and the press.
In outlining the scope of the technical review, EPA explained that RfDs are developed using
both science and professional judgment. The purpose of this expert technical review is to evaluate
and assess the scientific foundation and reasonableness of the IRIS entry. Although a long, and
often controversial, history surrounds Aroclor 1016, EPA asked the expert review panel to
concentrate on technical issues concerning the selection of a principal study, selection of critical
effects, selection of uncertainty factors, and weight-of-evidence conclusions. EPA also requested
panel members to consider four broad options for the Aroclor 1016 RfD as potential
recommendations to the RfD/RfC Work Group.
A balanced group of 13 expert technical reviewers representing government, academia,
environmental groups, and industry were selected to participate in the workshop. Selected reviewers
provided scientific expertise in the following disciplines: qualitative and quantitative effects of PCBs
in humans and in animals; PCBs and perinatal toxicity; PCBs and neurobehavioral effects; and
hazard and risk evaluation for data on health effects other than cancer.
EPA sought comments from these experts on the IRIS entry and related scientific sources.
Although EPA would welcome consensus, the expert technical review panel was assembled to
generate an array of expert opinions and recommendations. EPA did not expect to resolve all
uncertainties in the data and methods associated with the RfD for Aroclor 1016. EPA will use
reviewers comments and recommendations and conclusions drawn from this technical review
workshop as guidance in considering revisions to the RfD entry and maintaining the scientific
integrity of IRIS.
In addition to the technical review experts and observers, the Risk Assessment Forum invited
EPA staff who developed the RfD entry to serve as technical resources at the workshop. Also
available as technical resources to the workshop participants were Drs. Deborah Barsotti and Susan
Schantz, who conducted the underlying studies that served as the basis of the RfD.
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The workshop report is organized as follows. The report opens with a brief overview of the
workshop and background of the Aroclor 1016 RfD (section 1) and is followed by the chairperson's
summary (section 2) and the three chairs' summaries of technical issues discussed at the workshop
(section 3). Highlights of the technical reviewers' preliminary comments are provided in section 4.
Appendices to the workshop report consist of EPA premeeting materials, including the agenda, list
of participants, charge to reviewers, background materials, and premeeting comments (Appendices
A-E) and observers and observer materials, including the list of observers and observer comments
(Appendices F-G).
Dorothy E, Patton, Ph JX
Executive Director and Chair
Risk Assessment Forum
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SECTION ONE
OVERVIEW
GENERAL SUMMARY
The workshop provided a forum for the expert panel to technically review the scientific
underpinnings and reasonableness of all elements of the reference dose (RfD) for Aroclor 1016 as
entered into EPA's Integrated Risk Information System (IRIS). IRIS is an on-line database
developed by EPA to communicate chronic non-cancer and cancer health hazard information for
over 500 substances. Workshop participants contributed useful and substantive suggestions and
recommendations for EPA's RfD/Reference Concentration (RfC) Work Group to consider when
revising the RfD for Aroclor 1016. Section 3 of this report provides summaries and
recommendations prepared by the three workshop chairpersons.
In general, technical reviewers found the principal study to be well conducted. Because the
principal study was not designed to evaluate reproductive effects, information that would be useful
for assessing the significance of low birth weight as a critical effect could not be easily ascertained.
Several technical reviewers discussed whether low birth weight is in fact a sensitive and specific
effect. Moreover, some reviewers expressed the opinion that comparisons between exposed groups
of test animals might be a more appropriate measure of this effect than comparing test animals to
controls. Reviewers also had concerns about the appropriateness of the controls, and the placement
of animals from the colony into control groups and test groups was questioned. Technical reviewers
all agreed that additional information on weight and the colony was needed to monitor the variability
of body weight independent of other effects.
Technical reviewers agreed that the behavioral endpoint of learning and memory deficits
should have been addressed in the RfD for Aroclor 1016 and not overlooked due to a lack of
expertise within the RfD/RfC Work Group. Reviewers suggested that learning and memory deficits
may be of greater concern than low birth weight. Although the studies were considered well
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conducted, the research results indicate that further study is warranted to determine the specific
deficit or the underlying mechanism for the deficit Reviewers recommended that EPA obtain
adequate expertise to allow full consideration of this "co-critical" effect
Although some similarities exist between the blue pigmentation effects observed in animals
exposed to Aroclor 1016 and Aroclor 1248, discussions indicated that the hyperpigmentation
observed in test animals was qualitatively different than the type of pigmentation effects seen in
Aroclor 1248-exposed animals. Because limited published data are available on this subject,
technical reviewers recommended that the RfD/RfC Work Group consider the reviewers' premeeting
comments and workshop discussions in revising the RfD entry. At the time of the workshop,
however, reviewers did not consider hyperpigmentation a critical effect for Aroclor 1016.
While discussing exposure issues, reviewers commented that it is difficult to discuss work
performed 20 years ago given today's knowledge of polychlorinated biphcnyl (PCB) congeners.
Reviewers agreed that a body burden existed and that it was dose related, but they could not
determine if the measured concentrations were steady state. Reviewers also questioned, without
agreement, whether reaching a steady state is an important issue. Nonetheless, reviewers did reach
consensus on the recommendation that exposure levels should be recalculated using actual
analytically measured concentrations in feed (i.e., 0.700 +/- 0.130 ppm and 0.164 +/- 0.031 ppm)
rather than protocol-specified target tissue concentrations (i.e., 1 ppm and 0.25 ppm).
Considerable discussion took place on the issue of whether exposure to chemicals other than
Aroclor 1016 occurred. Technical reviewers agreed that the issue of potential contamination by
polychlorinated dihenzofurans (PCDFs) required no further action. Several recommendations were
made, however, concerning elucidation of whether other PCB contamination, specifically, Aroclor
1248, occurred. These include:
• reevaluating ctiromatograms (e.g., evaluate confounding factors [peaks 125 and 146]);
• quantitating Aroclor 1248 chromatogram peaks (i.e., look for consistency among
similar animals);
• comparing results of infants exposed to either Aroclor 1248 or Aroclor 1016;
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• comparing data on infants at birth versus nursing infants;
• examining whether the Aroclor 1016 was contaminated with Aroclor 1248;
• assessing the consistency of non-1016 PCB concentrations across animals;
• determining the source of the contamination; and
• developing a better approximation of the real dose.
In general, technical reviewers had difficulty discussing uncertainty factors issues associated
with the RfD for Aroclor 1016. Reviewers pointed out that until the issues associated with critical
effects and exposure are resolved, assigning uncertainty factors is premature: Gan uncertainty factors
/
be discussed independent of the confidence in the principal study? Technical reviewers suggested
that if values other than 10 are chosen as uncertainty factors, then comprehensive justifications
should be provided. Moreover, a modifying factor (MF) should be used if the" principal study has
flaws or uncertainty (e.g., issues concerning the controls or contamination).
Most reviewers expressed the opinion that the primary studies provided sufficient weight of
evidence. It was recommended that the results of non-Aroclor 1016 studies should be used in
weight-of-evidence conclusions if they are adequately qualified. Given the available data, reviewers
were unable to comment on the confidence of the oral RfD for Aroclor 1016 because additional
analyses are needed to evaluate the issues identified during the workshop on critical effects and
exposure.
A strong difference of opinion was voiced by technical reviewers on which of four options
under consideration should be recommended to EPA. The options, as posed in the Charge to
Reviewers (see Appendix C), are:
• Option A—Confirm the Aroclor 1016 RfD value with minor refinements.
• Option B—Confirm the Aroclor 1016 RfD value, but revise the text to include an
analysis of data limitations and uncertainties.
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• Option C—Revise the Aroclor 1016 R£D value and accompanying analysis.
• Option D—Provide other suggestions, including the availability of information
published after the RfD was entered on IRIS.
The disparate opinions offered were based on each reviewer's individual level of confidence in the
principal studies used to derive the oral RfD for Aroclor 1016.
Among issues discussed, technical reviewers recommended:
i
• recalculating exposure levels and the no observed adverse effect level (NOAEL)
based on the measured (actual) concentrations in feed; and
• addressing confidence in the overall RfD by:
— reexamining chromatograms;
— including behavioral effects; and
— evaluating the background (contaminant) levels of exposure to non-Aroclor
1016 chemicals.
BACKGROUND OF REFERENCE DOSE FOR AROCLOR 1016
Aroclors are commercial designations for complex mixtures of PCB isomers and congeners,
each consisting of two joined benzene rings and up to ten chlorine atoms. The four-digit number
in the Aroclor name indicates the type of isomer mixture (first two digits) and. the approximate
weight percent of chlorine in the mixture (last two digits). These PCB mixtures can be contaminated
with compounds such as PCDFs.
Widespread commercial use of PCBs as dielectrics in transformers and capacitors and as
cooling fluids in hydraulic systems, among other uses, began in the 1920s. A general ban of PCBs
took effect January 1977 under the Toxic Substances Control Act (TSCA). Although PCBs are no
longer produced in the United States, they are stable and persistent chemicals that have been
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distributed worldwide. Given the pervasiveness of PCBs, they are currently found in most
environmental media, including water, sediments, and soil.
I
Five years ago, EPA's RfD/RfC Work Group began to develop information for use by
scientists and regulators in assessing the risk to humans from exposure to Aroclor 1016 via contact
with contaminated environmental media. The work group collected and evaluated a broad range
of information in preparing an analysis for the reference dose, focusing on principal studies, endpoint
selection, uncertainty factors, and weight- of-evidence analysis. As hi all cases, given the range of
available information, establishing an RfD is ultimately a product of scientific judgment.
The RfD analysis was completed in December 1992. In January 1993, EPA entered the RfD
for Aroclor 1016 into IRIS. Responding to questions raised by an external organization, EPA senior
management requested that the IRIS entry be technically reviewed. The Risk Assessment Forum,
an EPA group separate from the RfD/RfC Work Group, convened this workshop to gather experts
. to independently review the RfD for Aroclor 1016 and related scientific sources.
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SECTION TWO
CHAIRPERSON'S SUMMARY OF THE WORKSHOP
Man Golub, Chair
California Regional Primate Research Center
University of California
Davis, CA
INTRODUCTION
On May 24 and 25,1994, EPA convened a technical workshop in Washington, DC, to assess
whether the reference dose for Aroclor 1016 is based on a scientifically responsible analysis that
represents full consideration of available data (see Appendix D) and whether that analysis is clearly
articulated in the RfD entry on IRIS. Thirteen technical reviewers participated in the workshop (see
Appendix A).
In the first part of the Charge to Reviewers (see Appendix C), members of the workshop
panel were invited to comment on the major elements of the RfD entry. While comments on all
technical aspects of the RfD entry were welcomed, comments on the following four elements were
of particular interest:
• selection of the critical study;
• selection of critical effects;
• selection of uncertainty factors; and
• weight of evidence conclusions.
In the second part of the charge, panel members were asked to consider a selection of four
possible recommendations concerning the RfD entry. Each reviewer was asked to identify a
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preferred option, highlighting primary considerations and noting any suggested changes. The options,
listed in full in the Charge to Reviewers, were to:
• confirm the RfD value with minor text refinements;
• confirm the RfD value, but revise the text to include a more comprehensive analysis
of the data;
• revise the RfD value and the accompanying analysis; or
• offer other suggestions (e.g., concerning use of data published after the RfD was
entered on IRIS in December 1992).
ISSUES
In the workshop panel's deliberations (see section 3 of this report for summaries), issues
identified in premeeting comments from review group members were considered under the general
topics of critical effects, exposure, and uncertainty factors. An added feature of the meeting was the
attendance of the principal investigators who conducted the critical studies. These investigators—Dr.
Deborah Barsotti and Dr. Susan Schantz—were on hand to serve as resource persons, and they were
called upon frequently to provide additional information relevant to the discussions. Relevant
information included confirmation of the lack of randomization or balance in maternal characteristics
in assigning animals to treatment groups.
A major barrier to the workshop panel's review was identified as the unavailability of data
that had been collected in the critical study. The absence of the information was attributable to the
time that had elapsed since the study was completed in 1980 and the objective of the study, which
did not concern development of an RfD. Concerning critical effects—one of three specific aspects
of the RfD reviewed during the workshop—the group agreed that it was important to obtain the
missing information to complete the review. Thus, the group's final recommendations were
considered provisional, pending the outcome of an analysis of the missing data. The issues awaiting
resolution concerned the appropriateness of the control group and the possible effect that other
chemicals besides Aroclor 1016 may have had on the study results.
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RECOMMENDATIONS
The workshop panel proposed a two-tiered recommendation. The first part of the
recommendation is to revise the NOAEL by using data from the analysis of Aroclor 1016 hi chow
to calculate administered dose. The NOAEL dose had been calculated from the diet formulation
(i.e., the amount of Aroclor 1016 added to the diet). This recommended revision would result in
a change in the concentration of Aroclor 1016 in the diet from 025 ppm to 0.17 ppm.
The second part of the recommendation is to obtain and analyze chromatogram and maternal
weight data from the critical study to provide an understanding of the impact that other chemicals
besides Aroclor 1016 had on the observed toxic effects, and to ensure that the control group was
appropriate despite the lack of randomization in group assignment It was the understanding of
workshop panel members that these data had been obtained during the critical study, even though
the current existence and location of the data were not known. This recommendation represented
a strong consensus within the group. Nonetheless, the group was split concerning the degree of
confidence that could be placed in the RfD, pending the outcome of additional data analyses.
Eight of the twelve panel members agreed that the statement of "medium" confidence could
be made pending the results of the analyses. Two members contended that confidence should be
"very low" or "highly uncertain" on the issue of causality pending the results of the analysis. Another
member characterized his confidence as "indeterminate" on the issues of background contamination
and appropriateness of controls pending the results of additional analyses, and one member said that
no confidence statement could be made.
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SECTION THREE
REVIEW GROUP SUMMARIES
Critical Effects Issues
Thomas M. Burbacher, Chair
Department of Environmental Health
School of Public Health and Community Medicine
University of Washington
Seattle, WA
INTRODUCTION
The primary basis for the RfD for Aroclor 1016 is a series of reports on a group of female
rhesus monkeys and their offspring published between 1984 and 1991 (see Barsotti and van Miller,
1984; Levin et al., 1988; Schantz et al., 1989; Schantz et al., 1991). The critical effect listed in the
RfD was reduced birth weight in rhesus monkey offspring (Barsotti and van Miller, 1984). Postnatal
neurobehavioral effects (learning and memory deficits) and transient dermal hyperpigmentation in
offspring (Schantz et al., 1989; Levin et al., 1988; Barsotti and van Miller, 1984) also were considered
but not listed as critical effects. The purpose of this review group session was to evaluate the
scientific basis for:
• EPA's selection of low birth weight as the critical effect for the Aroclor 1016 RfD;
• EPA's decision to exclude neurobehavioral effects as a critical effect for the Aroclor
1016 RfD; and
• EPA's decision to exclude dermal hyperpigmentation as a critical effect for the
Aroclor 1016 RfD.
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SELECTION OF LOW BIRTH WEIGHT AS THE CRITICAL EFFECT
Background
A significant decrease in the birth weights of rhesus monkey offspring was reported at a
maternal dose of 1 ppm Aroclor in diet (0.028 mg/kg-day intake) but not at 0.25 ppm (0.007 mg/kg-
day intake) (Barsotti and van Miller, 1984). The study results were used as the basis for the RfD
of 0.07 jtg/kg-day for Aroclor 1016. Although the mean (+SD) birth weights of rhesus monkey
offspring studied were reported (table 1), the report did not include the weight; of the individual
monkeys, the offspring sex distribution in each group, or information regarding the maternal or
paternal characteristics of the groups. The premeeting comments of the review panel indicated that
this information is considered crucial for evaluating the scientific basis of the selection of low birth
weight as the critical effect for the Aroclor 1016 RfD. Thus, in response to a request for additional
information about the study from the review workshop's co-chairs, EPA provided the information
shown in tables 2,3, and 4.
The workshop panel considered the additional information useful, but was concerned about
the lack of available data on the parents of the study offspring. Information regarded as particularly
relevant included:
• genetic stock of the animals;
• maternal age, weight, parity, time in colony; and
• paternal age, weight, and reproductive history.
Additional information regarding the experimental protocol for control and exposed adults also was
considered important
This information was considered important .because these factors also may influence birth
weight. Thus, if these factors were not considered in the design of the study, the association between
Aroclor exposure and reduced birth weight might not be as straightforward as the one presented in
the RfD entry for IRIS. Information regarding possible contamination of the Aroclor diet also was
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TABLE 1
WEIGHTS OF INFANTS WHOSE MOTHERS WERE EXPOSED TO AROCLOR 1016
PRIOR TO AND DURING PREGNANCY AND LACTATION
Level of Aroclor 1016 In Diet (jtg/g)
1.0 (N=8)
0.25 (N=8)
Controls (N=9)
Average Birth Weight (g)
(±SD)
422 (27)
491 (23)
512 (64)
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TABLE 2
ADDITIONAL DATA RELEVANT TO LOW BIRTH WEIGHT: CONTROLS
(Provided by EPA, 5/19/94)
Offspring
No.
AG63
AG65
AG66
AG68
AG70
AG71
AG74
AG88
AG96
Sex
F
M
F
F
M
M
M
M
F
Birth
Date
4/22/78
4/26/78
4/26/78
5/03/78
5/04/78
5/08/78
5/27/78
8/13/78
9/28/78
Birth Weight
(g)
510
565
550
400
560
595
495
570
445
Gestation**
Mother
No.
PP12
PP13
PP14
PP18
PP33
PP37
PP48
PF74
PP66
Father
No.
PP06
PP02
PP01
1630*
PP05
PP02
1630
PP06
PP02
*Father No. 1630 received Aroclor 1248.
**Data exist but are not available for review.
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TABLES
ADDITIONAL DATA RELEVANT TO LOW BIRTH WEIGHT: 1-PPM GROUP
(Provided by EPA, 5/19/94)
Offspring
No.
AG81
AG85
AG90
AG92
AG93
AH02
AH06
AH14
Sex
F
F
M
M
F
M
F
F
Birth
Date
7/07/78
7/28/78
8/30/78
9/02/78
9/09/78
10/06/78
10/18/78
12/19/78
Birth Weight
(g)
430
410
480
385
440
405
425
405
Gestation
159
164
164
152
165
163
169
151
Mother
No.
PF79
PP88
PP89
PP70
PP87
PP76
PP81
PP64
Father
No.
1632*
PP01
PP05
PP02
PP05
PP01
PP04
PP04
*Father No. 1632 received Aroclor 1248.
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TABLE 4
ADDITIONAL DATA RELEVANT TO LOW BIRTH WEIGHT: 0.25-PPM GROUP
(Provided by EPA, 5/19/94)
Offspring
No.
AG77
AG79
AG87
AG94
AG97
AH03
AH04
AH13
Sex
F
F
F
F
F
M
F
M
Birth
Date
5/27/78
7/06/78
8/09/78
9/14/78
9/27/78
10/12/78
10/14/78
12/05/78
Birth Weight
(g)
480
495
470
515
495
450
525
500
Gestation**
169
163
162
171
166
164
161
165
Mother
No.
PP83
PP82
PP56
PP75
PP62
PP67
PF72
PP78
Father
No.
PP03
PP01
PP04
PP06
PP03
PP03
1632*
PP05
*Father No. 1632 received Aroclor 1248.
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considered important by the panel; however, since this topic was the focus of a subsequent workshop
session, further discussion was postponed.
During the workshop, it was determined that data on the age of the mothers did not exist,
since all were feral animals imported to the facility and no effort was made to estimate ages based
on dentition. It was also determined that, while the true parity of the mothers was not known, data
regarding colony parity were available. Colony parity of the control mothers was thought to be
around 3, while colony parity of exposed mothers was known to be 0. The difference was
attributable to the length of time that the mothers were in the colony prior to the study; the control
mothers were imported in 1973 and the exposed mothers in 1976, approximately 1 year prior to the
beginning of the study. While the females were imported 3 years apart, it was determined that the
same primate supplier was used for each group and the location of the females prior to importation
was likely the same. Although very little data regarding maternal size were included in the original
report, maternal weights were noted throughout the study. If available, data on maternal weight at
initiation of the study and at critical tunes during the study would provide important information
regarding the possible effects of maternal size or maternal weight gain on birth weight. Weight and
reproductive data also were collected on the fathers in the study, but no data exist regarding the age
of these animals. In regard to experimental protocol, it was determined at the workshop that all
procedures were performed on exposed and control subjects throughout the study.
Review Group Recommendations
While the review group understood the difficulties associated with gathering information on
a study that is over 15 years old, it felt that every effort should be made to collect additional data
on the parents of the offspring so that the reduced birth weight effect can be adequately evaluated.
The work group also made the following specific recommendations:
• Available data regarding characteristics of the parents of offspring studied should be
reviewed to provide a better description of the control and exposure groups. Since
no data exist regarding parental age and since colony parity and time in the colony
are known to differ across the groups, the primary goal of such a review should be
to provide further data regarding maternal weight. Data indicating that the maternal
weights across the groups were similar would strengthen the conclusion that the
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reduced birth weight effect was associated with Aroclor 1016 exposure. Maternal
weight gain during the study should also be examined since the little data that were
included in the original report indicate that maternal weight gain from the beginning
of the study until the end, when the offspring were weaned, was substantially lower
for the 1-ppm exposure group when compared to the 0.25-ppm group. This may
indicate that the Aroclor exposure hindered normal maternal weight gain during
crucial periods of offspring development.
The proposed RfD entry indicates a significant reduction in weights for the 1-ppm
group when compared to the controls. The results of a statistical comparison of the
birth weights of the two exposed groups also should be included in the entry to
indicate whether the difference in the birth weights of the exposure groups is
significant
The association between Aroclor body burden and birth weight should be
investigated. Since data are available regarding PCB levels in skin or fat, analysis of
the birth weights according to maternal and offspring body burden using the results
of the biopsies should be reported.
A comparison of birth weights reported for this study against normative data from
rhesus monkeys should be included in the entry. Data from the same colony of
animals during the same period of time also would strengthen the basis of the critical
effect determination.
EXCLUSION OF NEUROBEHAVIORAL EFFECTS AS A CRITICAL EFFECT
Background
A significant increase in the number of trials required to learn a simple spatial discrimination
task was reported for offspring at a maternal dose of 1 ppm Aroclor in diet (0.028 migVkg-day intake),
but not at 0.25 ppm (0.007 mg/kg-day intake) (Schantz et al., 1989). A significant decrease in the
number of trials required to learn a simple shape discrimination/reversal task also was reported for
offspring at a maternal dose of 1 ppm Aroclor in diet (0.028 mg/kg-day intake), but not at 0.25 ppm
(0.007 mg/kg-day intake) (Schantz et al., 1989). Finally, a significant decrease in the percent of
correct responses for a delayed spatial alternation task was reported for offspring at a maternal dose
of 1 ppm Aroclor in diet (0.028 mg/kg-day intake) when compared to offspring receiving 0.25 ppm
(0.007 mg/kg-day intake) but not to controls (Levin et al.; 1988).
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Schantz et al. (1989) indicated that results of the discrimination-reversal study are consistent
with effects attributable to hipppcampal damage, as performance on spatial tasks is adversely
affected while performance on object-oriented tasks is facilitated. The results of the delayed spatial
alternation task, indicating that the 1-ppm offspring performed at a lower rate of correct response
than controls while the 0.25-ppm offspring performed at a higher rate than controls, were considered
possibly related to the differential effects of exposure on attention (Levin et al., 1988).
The RfD entry indicates that "evaluation of these data is complicated by possible
inconsistencies hi the outcome of both the discrimination-reversal learning tests (learning was
unpaired and facilitated on different problems) and the delayed spatial alternation test (performance
significantly differed between the two exposed groups, but not between either test group and the
control)." Additional information provided to the workshop group indicated that the effects on
learning were not chosen as a critical effect due to the "biphasic nature of the response and the lack
of statistical power hi measuring differences to controls."
Review Group Recommendations
The statements above quoted from the RfD entry do not provide sufficient evidence to
discount the inclusion of spatial discrimination effects as a critical effect for Aroclor 1016. Offspring
from the 1-ppm maternal dose group required 2.5 times as many trials as the controls to learn the
spatial discrimination. The design of the discrimination-reversal study was adequate and the
procedures were appropriate for the age of the monkeys. Moreover, the results of the object-
oriented discrimination-reversal task should not be considered contrary evidence for an Aroclor
effect on spatial learning. The statement regarding "the biphasic nature of the response" addresses
concerns regarding the delayed spatial alternation data but does not address the significant learning
decrement observed in the spatial discrimination task. As a result, the review group made the
following recommendations:
• Discrimination-reversal data should be reviewed to determine whether the number
of trials in which the monkeys did not respond (i.e., balk trials) differed across the
groups and influenced the results.
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Data should be provided regarding the performance of the groups across trials (e.g.,
learning curves).
The RfD entry indicates a significant increase in the number of trials that monkeys
in the 1-ppm group required to learn a discrimination task when compared to the
controls. The results of a statistical comparison of the performance of the two
exposed groups also should be included in the entry to indicate whether the
difference in the number of trials needed by monkeys in die exposure groups to learn
the discrimination task is significant.
The association between Aroclor body burden and performance on these tasks
should be investigated. Since data are available regarding PCS levels in skin or fat,
analysis of the learning data according to maternal and offspring body burden using
the results of the biopsies should be reported.
Based on the results of the studies at this time, the deficit observed hi spatial
discrimination learning hi the 1-ppm group should be considered a critical effect for
Aroclor 1016.
EXCLUSION OF DERMAL HYPERPIGMENTATION AS A CRITICAL EFFECT
Background
Barsotti (1980) reported that "six of the 8 infants of the 1.0 ppm group, 1 of the 8 infants
of the 0.25 ppm group and 2 of the 7 infants from the 0.025 ppm group developed
hyperpigmentation. These changes were similar to those described in the infants that were exposed
to Aroclor 1248." The hyperpigmentation effects were summarized in the RfD entry in the following
manner: "Hyperpigmentation was present at birth in the low- and high-dose infants but did not
persist once dosing stopped. This clinical change was determined not to be a critical adverse effect."
Review Group Recommendations
No information was provided in the RfD entry concerning the determination not to select
hyperpigmentation as a critical effect. Apparently the basis of the decision was that the effect was
only transient. After questioning whether hyperpigmentation developed postnatally or was present
at birth, the review group determined that the RfD entry was not accurate and that
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hyperpigmentation developed postnatally. Details regarding the characteristics of the
hyperpigmentation in the exposed offspring were not found hi the original report (Barsotti, 1980)
or in the RfD entry. Apparently the hyperpigmentation was not similar to the chloracne and
pigmentation observed hi humans exposed to tetrachlorodibenzo-p-dioxin (TCDD); rather, it
appeared as an exaggeration of the blue pigmentation pattern commonly seen hi rhesus neonates.
Based primarily on the fact that the hyperpigmentation does not match clinical signs hi humans, the
review group recommended the following:
• The RfD entry should be corrected to indicate that the hyperpigmentation was not
present at birth but developed postnatally.
• The hyperpigmentation should be described hi detail and compared to the known
clinical signs in humans of PCB exposure, such as chloracne and pigmentation.
• Based on the results of the study, at this time hyperpigmentation should not be
considered a critical effect for Aroclor 1016.
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Exposure Issues
Nancy Kim, Chair
Division of Environmental Health Assessment
New York State Department of Health
Albany, NY
INTRODUCTION
Premeeting comments on exposure issues that were addressed by the groujp focused on two
minor areas and one major aspect of the critical study. The two minor issues discussed concern the
doses of Aroclor 1016 that the rhesus monkeys in the study received and whether steady-state
conditions were reached before the animals were bred. The major issue discussed concerns whether
the study annuals were exposed to other chemicals, and if so, what the levels of those other
exposures are and what the effect of these exposures might be on the outcome of the study and on
the proposed RfD for Aroclor 1016.
DOSE
Background
The monkeys were fed diets calculated to contain 1.0 ppm, 0.25 ppm, and 0 ppm of Aroclor
1016. These concentrations were used to calculate the average total intake of 18.41 +/- 3.64 mg/kg
and 4.52 +/- 0.56 mg/kg for the 1.0-ppm and 0.25-ppm dose groups, respectively (Schantz et al.,
1989). The three diets were analyzed for Aroclor 1016 content and the actual concentrations were
0.700 +/- 0.130 (N=12) ppm, 0.164 +/- 0.031 (N=12) ppm, and 0.005 +/- 0.001 (N=9) ppm in the
1.0-ppm, 0.25-ppm, and control chow groups, respectively.
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Review Group Recommendations
The review group recommended that dose levels be recalculated using the actual
concentrations, which would result in a reduction in dose levels of about 30 percent The group also
recommended that an attempt be made to correlate body burden measurements with health endpoint
data.
STEADY-STATE CONDITIONS
Background
The issue of whether the monkeys' body burden had reached steady-state conditions at the
time of conception could be important for determining the uncertainty factor if the study is
determined not to be a chronic study. In the study, the level of PCBs hi the adipose tissue increased
during the dosing period between 4 months and 7 months, which could indicate that steady-state
conditions had not been reached. To reach a conclusion on this issue, however, a pair-wise
comparison would have to be made rather than using a comparison of the average Aroclor 1016
adipose tissue concentrations.
Review Group Recommendations
The review group considered the data inadequate to reach a conclusion on steady-state
conditions and felt that the issue is unlikely to be resolved. Thus, the review group found no basis
for recommending that the issue be investigated further.
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POSSIBLE EXPOSURE TO OTHER CHEMICALS
Background and Discussion
The review group focused much of its discussion on the possibility that the monkeys were
exposed to other substances besides Aroclor 1016. Along with exposure to Aroclor 1016 in the
control diet, specific substances that were discussed include PCDFs and other possible Aroclors,
particularly Aroclor 1248.
Barsotti and van Miller (1984), Barsotti's thesis (1980), and the IRIS document all stated in
slightly different ways that the Aroclor 1016 fed to the monkeys did not contain chlorinated
dibenzofurans (CDFs). This issue was clarified by Dr. Deborah Barsotti, who stated at the workshop
that J. McKinney had analyzed the Aroclor 1016 used in the experiments to determine the tri-,
tetra-, penta-, and hexa-CDF content. None was observed at the detection limit of 5 ppb. The
consensus within the review group was that this additional information clarified the issue and that
no further information was needed.
Another exposure issue concerned whether Aroclor 1016 was in the diet of the control
animals. This issue was raised because Barsotti (1980 at p. 185) states, "Control adipose samples
contained PCBs based on Aroclor 1016 standard at the level of 0.69 +/- 0.38 /ig/gm on the lipid
basis. Three animals sampled had adipose PCB levels below the limit of confident detection for this
analysis." This finding is unexpected because there was no known source of exposure to Aroclor
1016. Dr. Barsotti stated that the analytical results were quantitated as Aroclor 1016, without a
specific determination as to which Aroclors were present. The PCB mixture might have come from
the fish meal in the Purina monkey chow. The Great Lakes fish used in the chow contained PCBs,
although probably not Aroclor 1016. Dr. Barsotti's statement helped to alleviate the concern and
clarified that Aroclor 1016 was not known to be in the control diet. This issue could be clarified,
however, by looking at the chromatograms and confirming the identity of the PCB mixture.
Most of the review group's discussions about exposure focused on the likelihood of exposure
to other possible Aroclors, particularly Aroclor 1248. Barsotti (1980 at p. 192) states, "We have
shown that the concentration of PCBs in control monkey chow is in the range of 1 - 50 ppb on the
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basis of an Aroclor 1248 standard." A second question about Aroclor 1248 exposure arose because
peaks with relative retention" times of 125 and 146 were on the gas chromatograms of the tissue
samples; these peaks may be indicative of Aroclor 1248 exposure.
The importance of possible Aroclor 1248 exposure depends on whether contamination is
consistent across all exposure groups. This is partially dependent on whether the contamination was
in the chow from the manufacturer or whether some contamination was introduced during the
pelleting operation. Judging from premeeting comments, some review group members considered
this a relatively minor issue because (1) the contamination appeared to be consistent across all dose
groups and at orders of magnitude less than the Aroclor 1016 exposure, (2) body burden data were
available, and (3) hyperpigmentation was not observed in the control animals. Others considered
this a major issue, given that some of the effects can be caused by Aroclor 1248 (or other, dioxin-like
chemicals), and a causal association cannot be established without a definitive chemical
characterization of the diet.
Review Group Recommendations
The review group made the following recommendations:
The 1.0-ppm9 0.25-ppra, and control chow were analyzed 12, 12, and 9 times,
respectively, throughout the study. Data and chromatograms should be examined to
determine the Aroclor 1248 content.
Chromatograms for the tissue analyses could be examined, looking for consistency
among similar animals in levels of peaks that are not from Aroclor 1016. The data
for the control and exposed animals would have to be reviewed separately because
the control animals were older and had been on commercial chow longer and, thus,
would be expected to have higher levels of Aroclor 1248 in their tissues.
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Chromatograms for the tissues of the offspring could be reviewed. Reviewing results
for tissues at birth might be easier and would have less confounding information than
the chromatograms of tissues after nursing. Levels of individual peaks from tissues
after nursing would be more complex because of greater differences in, for example,
metabolism and excretion when the chemicals were ingested with milk in contrast to
exposure in utero.
Chromatograms from tissues of the Aroclor 1016 infants could be compared to those
from the Aroclor 1248 infants, looking for similarities. This information could help
to determine the magnitude of the exposure to Aroclor 1248.
Birth weight study results from the infants on Aroclor 1248 could be compared with
the birth weight results for the infants on Aroclor 1016. For example, the average
birth weight in the 1.0-ppm Aroclor 1016 infants was 422 g +/- 29 g and the average
birth weight of the Aroclor 1248 infants was 476 g +/- 42 g. The experimental
design would have to be compared; however, these data, at first glance, suggest that
Aroclor 1016 has a greater effect on birth weight than Aroclor 1248. If this were
true, contamination by Aroclor 1248 may be of less importance.
In reviewing the chromatograms, one would need to keep in mind the difference in
the pharmacokinetics of the various congeners.
The chromatogram of the Aroclor 1016 mixture that was used to prepare the chow
could be examined to look for Aroclor 1248 peaks.
In general, when reviewing the chromatograms, two different approaches are
possible! One approach would be to "eye-ball" the similarities or differences; the
other would be to quantitate the different peaks. It may be possible to combine
these approaches in an efficient manner. For example, "eye-balling" a number of
chromatograms may help to suggest an answer to some of these questions. Then the
peaks of a minimal number of chromatograms could be quantified to document the
findings.
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Uncertainty Factors Issues
Man Golub, Chair
California Regional Primate Research Center
University of California
Davis, CA
INTRODUCTION
The review group's consideration of uncertainty factors (UFs) began with a review of changes
that EPA's RfD/RfD Work Group made during development of the RfD between January 1990 and
January 1993, when the entry was loaded onto IRIS. During this development process, a number
of alternatives were considered for the value of the five UFs. In addition, the statement concerning
weight of evidence, the studies cited as supporting the RfD, and the statement and justification for
the section on confidence evolved hi response to discussions by the RfD/RfC Working Group and
comments received from an EPA internal peer review.
ISSUES IDENTIFICATION
The workshop's technical review group began its discussions with identification of several
issues concerning UFs derived from the workshop's premeeting comments:
• Some review group members felt that the value of the composite uncertainty factor
'• was appropriate and were not concerned about the distribution among the various
component UFs. One reviewer suggested eliminating the presentation of individual
UFs.
• The UFS (subchronic to chronic) received the most attention hi premeeting
comments. All possible alternatives for the UFS were suggested by individual
reviewers, including not using this factor and using values of 1, 3, or 10. Use of
these options would depend on whether the critical study was considered to be
subchronic, chronic, or "more than subchronic, less than chronic."
• Values of 1 rather than 3 were suggested for the UFA (interspecies extrapolation)
and the UFH (intraspecies extrapolation) based on the strong similarity of non-human
primates to humans and the strong identification of the fetus as a member of a
sensitive population.
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Two reviewers commented on the possibility of reconsidering the dose selected as the
NOAEL and altering UFs based on this result. One review group member suggested
that the 0.25-ppm diet group be used as the LOAEL rather than the NOAEL.
Another reviewer suggested that a modifying factor (MF) be added to take into
account that the NOAEL might be lower if a benchmark dose, based on modeling
of the dose-response curve, were used. .
REVIEW GROUP RECOMMENDATIONS
Weight of Evidence
The review group considered it important to discuss the weight of evidence section of the
RfD entry before addressing issues concerning UFs. The discussion that ensued focused on whether
studies that did not use Aroclor 1016 dosing should be cited as supporting evidence. This group of
studies primarily report on the consequences of human exposure to PCBs via environmental media.
The review group recommended that these studies not be used as supporting evidence for
hyperpigmentation since the effect in monkeys did not resemble that reported for TCDD/PCB
exposure in humans. In general, studies in humans where exposures were not limited to Aroclor
1016 should not be cited as supporting evidence, the review group recommended, unless the effects
reported were similar to those observed in the critical study for the RfD. Even then, the degree of
support provided by such studies should be qualified. This recommendation was made specifically
in regard to information from the Yusho and Yu-Cheng poisoning incidents (Rogan, 1989), and the
studies of birth weight from Michigan populations exposed to PCBs via fish consumption.
Similarly, the review group suggested that more emphasis be given to the studies of Taylor
et al. (1984,1989), in which occupational exposures were more specific to Aroclor 1016. A review
group member also commented that Aroclor 1016 had a fairly unique or characteristic composition
of congeners compared to other PCB commercial mixtures. Thus, scientific data comparing mixtures
suggest that data from environmental exposures in humans is not as valuable as supporting evidence
for Aroclor 1016 as for some other commercial mixtures.
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On another issue, one review group member said that a discussion of the differences between
mink and human reproductive characteristics should be included if data on reproduction in mink are
cited as supportive. Another group member suggested that the section on supporting studies be
reorganized and reworded to reflect the relative weight of supporting studies.
Values for Uncertainty Factors
In the discussion about values for specific UFs, review group members noted that, while non-
human primates are known to be similar to humans, there are major differences between non-human
primate species. Moreover, the rhesus monkey is not necessarily representative of all non-human
primates. A group member pointed out that the supporting studies on similarity between monkeys
and humans in FCB metabolism and clearance were limited to two congeners. Thus the UFA was
appropriately set at 3 rather than 1. Review group members also commented that use of data
developed by Hugh Tilson (of the EPA Health Effects Research Laboratory at Research Triangle
Park, NC) to justify behavioral outcome similarities between monkeys and humans should be
qualified by the fact that these studies did not use Aroclor 1016.
A review group member commented on the UFH, noting that if behavioral endpoints were
considered co-critical, the RfD's statement on transplacental exposure would not be appropriate
since transmammary exposure also occurred. A fairly extensive discussion of the history and value
of the use of behavioral endpoints for RfD determination followed. A consideration of problems
and issues past and present resulted in general agreement regarding qualified support for the use
of behavioral endpoints in RfD development.
The review group did not feel it appropriate to discuss the UFS and UFD (database
deficiencies). One review group member, however, provided a suggestion and strong justification
for use of an MF to cover issues of background contamination and appropriateness of controls.
When carried forward to.other discussions, this suggestion retained its strength.
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Confidence
Discussion of the RfD entry's section on confidence immediately focused on the importance
of the analysis of chromatograms and weight data in allowing selection of a level of confidence. This
discussion carried over into formulation of a recommendation from the workshop panel in the final
session of the meeting.
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SECTION FOUR
HIGHLIGHTS FROM TECHNICAL REVIEWERS' PRELIMINARY COMMENTS
Prior to the workshop, each technical reviewer was asked to prepare written comments on
the major elements of the RfD entry, covering selection of a principal study, selection of critical
effects, selection of uncertainly factors, and weight-of-evidence conclusions. Relying on their
technical knowledge and best professional judgment, reviewers also considered four broad options
as potential recommendations to the RfD/RfC Work Group. Appendices C and D provide the
Charge to Reviewers and background information, respectively. Technical reviewers' premeeting
comments are presented in Appendix E.
Three critical health effects issues were identified by technical reviewers:
• low birth weights;
• learning and memory deficits; and
• hyperpigmentation.
The point was made by several reviewers that the principal study was not designed as a
reproductive study; rather, it was designed to investigate metabolic issues—the low birth weight
effect was unexpected. As a result, reviewers identified the following factors other than Aroclor
1016 as important for evaluating the low birth weight effect:
• maternal age;
• maternal weight and weight gain;
• maternal parity;
• time hi colony;
• paternal factors (e.g., age, weight, time in colony, and reproductive history);
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• colony versus study controls (i.e.,. What was the protocol during the study?);
• contamination of diet;
» Aroclor 1016 feeding protocol;
• paternal exposure;
-• • external factors (e.g., housing and temperature);
.*
• identification of genetic stock of controls and test animals;
• randomization; and
• comparison of exposed animals only.
Regarding the last two factors, many comments were made on the sources of animals and whether
any counterbalancing occurred in selecting test and control animals from different groups.
Reviewers inquired, for instance: How representative were control animals to test animals? Were
they totally randomized? If different exposures are being compared, reviewers suggested, then
randomization is a critical factor that must be considered.
To measure learning and memory, test animals were tested at 14 months and 4 years of age
using several discrimination-reversal (DR) problems (e.g., simple spatial DR, modified spatial DR,
color DR, shape DR, and delayed spatial alternation). Technical reviewers questioned why learning
and memory deficits were not listed as a "co-critical" effect. Reviewers also took issue with the
reason this effect was not chosen as critical: the reasoning was based on the biphasic nature of
effects and the lack of statistical significance from controls, but reviewers pointed out that DR is
considered a straight effect, not biphasic. Technical reviewers also observed that deficits in original
learning and borderline effects on reversal are similar to deficits observed in non-human primates
with discrete lesions on the prefrontal cortex. Other data identified as necessary for assessing this
effect are general study conditions, postnatal exposures, and learning curves.
As with behavioral endpoints, reviewers questioned why hyperpigmentation was not
considered a "co-critical" effect. Comments covered such issues as whether hyperpigmentation is a
clinical or a toxicological effect. Reviewers also queried: Is the hyperpigmentation an indication
of exposure and therefore an effect? If the finding is similar and consistent regarding effects with
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other chlorinated compounds, can it be ignored? It was noted that hyperpigmentation is usually
associated with exposures to FCBs with higher chlorination than Aroclor 1016.
Technical reviewers' comments addressed three issues related to exposure:
• Was a steady-state concentration reached?
• Was the exposure dose calculated using the protocol-specified target tissue
concentration (i.e., 1 ppm) or the actual concentration measured in the feed (i.e., 0.7
ppm)?
• What other chemicals were measured (e.g., PCDFs, Aroclor 1016 in control diets,
Aroclor 1248, other PCBs) and what concentrations were detected?
Referring to Table 6-1 hi Dr. Deborah Barsotti's thesis (1980) on levels of PCBs fa the
adipose tissue of female monkeys consuming Aroclor 1016, comments were made on the different
levels observed between the 1-ppm and 0.25-ppm groups. The variance observed in the 1-ppm group
was explained by the rapid metabolism and excretion of most Aroclor 1016 congeners. Because only
total PCBs were measured, however, it is difficult to tell which congeners were at a steady state.
Because samples were collected and analyzed for every batch of feed prepared, the
concentrations measured were considered representative of the entire study period. Exposure was
calculated, however, using the protocol-specified target tissue concentrations of 1 ppm (18.41 mg/kg)
and 0.25 ppm (4.52 mg/kg), rather than the actual measured levels (0.700 +/- 0.130 and 0.164 +/-
0.031) in the feed. Reviewers indicated that doses should be recalculated based on actual measured
concentrations in the feed.
Many comments addressed the potential contamination of the feed with other chemicals.
The Aroclor 1016 stock was analyzed for PCDFs, but measured concentrations were less than 5 ppb,
the analytical detection limit. Concern was raised over the presence of Aroclor 1016 in five out of
eight animal's adipose tissue before dosing occurred; Aroclor 1016 would not be expected. It was
pointed out, however, that the commercial monkey chow contained fish meal that was prepared from
fish caught in the Great Lakes (which is contaminated with PCBs). The monkey chow manufacturer
certified that a minimum amount of PCBs was present, but would not specify which congeners.
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Low levels (0.50 ppb) of Aroclor 1248 and other FCBs were detected in the commercial
monkey chow, and conclusions about the presence of these non-Aroclor 1016 PCBs were made based
on observed effects (i.e., hyperpigmentation). The lack of information on the processing and analysis
of feed for control and test animals, however, left many questions unanswered:
• Was the food contamination from the manufacturer or from the pelleting operation?
• What analytical data on tissues and diet are available?
• When was the feed analyzed?
• Was the feed processed differently for control and test animals?
• If Aroclor 1248 was present in the feed, why were effects not seen in controls and
at all exposure levels?
• What effect does inter-animal variability have on the results?
Various explanations for the presence of Aroclor 1248 were presented, including:
• Since Aroclor 1248 also was being studied at this facility at the same time studies
were being conducted on Aroclor 1016, some of the animals could naive inadvertently
been exposed to Aroclor 1248.
• Aroclor 1248-like peaks on chromatograms could be the result of bioaccumulation,
given the nature of the congeners.
One reviewer asked: At what level of contamination does the Aroclor 1016 data become unusable?
Although technical reviewers generally considered the total uncertainty factor of 100 selected
for the Aroclor 1016 RfD to be reasonable for the chosen critical effect, several reviewers raised
issues concerning the assignment of individual uncertainty factors:
• If little concern exists about the distribution and justification of individual
uncertainty factors (e.g., UF^ UFH, UFD, and UFS), could the discussion of
individual uncertainty factors be eliminated?
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• Uncertainty factors for interspecies (UFJ and intraspecies (UFg) extrapolations
should not both rely on species similarities. Also, species similarities should not be
used unless sufficient data exists to support such a determination.
• The uncertainty factor for extrapolation from subchronic to chronic exposures (UFS)
should be reevaluated based on a determination of whether (and when) a steady-
state body burden had been reached.
Technical reviewers' comments on the weight-of-evidence conclusions spanned from the
specific to the general. Overall, many of the reviewers found that the, primary studies provided
sufficient weight of evidence. One reviewer suggested that the discussion should be reorganized to
reflect the two-fold purpose of the section: to summarize the remaining literature and to justify the
critical study. Several reviewers recommended that the mink studies not be used as supporting
evidence. Another reviewer asked that the role of behavioral studies as supporting evidence be
clarified.
Reviewers' preliminary comments indicated that all four recommendations posed in the
Charge to Reviewers—options A, 8, C, and D—were considered viable recommendations, with more
reviewers favoring options B and C. If, however, the exposure levels are adjusted for the actual
concentrations in the feed versus what was called for in the protocol, then options A and B can be
eliminated since the NOAEL will be recalculated. One reviewer suggested that the data be
reexamined to determine if a basis exists to support the RfD.
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SECTION FIVE
REFERENCES
Barsotti, D.A. 1980. Ph.D. Thesis. Gross, clinical, and reproductive effects of polychlorinated
biphenyls in the rhesus monkey. August, 1980. Available through the University Library,
University of Wisconsin, Madison, Wisconsin.
Barsotti, D.A., and J.P. Van Miller. 1984. Accumulation of a commercial polychlorinated biphenyl
mixture (Aroclor 1016) in adult rhesus monkeys and their nursing infants. Toxicol. 14:31-44.
Levin, E.D., S.L. Schantz, and R.E. Bowman. 1988. Delayed spatial alternation deficits resulting from
perinatal PCB exposure in monkeys. Arch. Toxicol. 62:267-273.
Rogan, WJ. 1989. Yu-Cheng, Chapter 14. In: Halogenated Biphenyls, Terphenyl, Napthalenes,
Dibenzodioxins and Related Products, 2nd ed., R.D. Kimbrough and A.A. Jensen, Ed.
Elsevier Science Publishers Amsterdam.
Schantz, S.L., E.D. Levin, and R.E. Bowman. 1989. Effects of perinatal PCB exposure on
discrimination-reversal learning in monkeys. Neurotoxicol. Teratol. 11:243-250.
Schantz, S.L., E.D. Levin, and R.E. Bowman. 1991. Long-term neurobehavioral effects of perinatal
polychlorinated biphenyl (PCB) exposure in monkeys. Environ. Toxicol. Chem. 10:747-756.
Taylor, P.R., C.E. Lawrence, H.L. Hswang, et al. 1984. Polychlorinated biphenyls: Influence on
birthweight and gestation. Am. J. Public Health. 74:1153-1154.
Taylor, P.R., J.M. Stelma, and C.E. Lawrence. 1989. The relation of polychlorinated biphenyls to
birth weight and gestational age in the offspring of occupationally exposed mothers. Am. J.
Epidemiol. 129:159-169.
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APPENDICES A-E
EPA PREMEETXNG MATERIALS
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APPENDIX A
FINAL PARTICIPANT LIST
A-l
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£
LLI
U.S. Environmental Protection Agency
TECHNICAL REVIEW WORKSHOP ON THE REFERENCE DOSE (RfD)
FOR AROCLOR 1016
Barcelo Washington Hotel
Washington, DC
May 24-25,1994
FINAL PARTICIPANT LIST
Henry Anderson
Chief Medical Officer
Wisconsin Bureau of Public Health
1400 East Washington Avenue - Room 96
Madison, WI 53703
608-266-1253
Fax: 608-267-4853
Douglas Arnold
Research Scientist
Toxicology Research Division
Health and Welfare Canada
Sir Frederick G. Banting
Research Centre (2nd E)
Tunney's Pasture
Ottawa, Ontario K1AOL2
Canada
613-957-0992
Fax: 613-941-6959
Thomas Bnrbacher
Research Associate Professor
Department of Environmental Health
School of Public Health and
Community Medicine
University of Washington
(SC-34)
Seattle, WA 98195
206-685-7674
Fax: 206-685-4696
Peter deFur
Senior Scientist
Environmental Defense Fund
1875 Connecticut Avenue, NW
Washington, DC 20009
202-387-3500
Fax:202-234-6049
Mari Golub
California Regional Primate Research Center
University of California - Davis
Pedrick and Hutchinson Road
Davis, CA 95616
916-445-0933 (Monday and Wednesday)
916-752-5119 (Tuesday and Thursday)
Fax:916-327-7340
RoIfHarhmg
Professor of Environmental Toxicology
The University of Michigan
2504 School of Public Health
109 South Observatory
Ann Arbor, MI 48109-2029
313-936-0787
Fax: 313-971-418Q
Nancy Kim
Director
Division of Environmental Health Assessment
New York State Department of Health
2 University Place - Room 350
Albany, NY 12203-3399
518-458-6438
Fax: 518-458-6436
(over)
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Ralph Kodell
Deputy Director Richard Seegal
Division of Biometry and Risk Assessment Research Scientist IV
National Center for Toxicological Research Wadsworth Center for
3900 NCTR Road (HFT-20) Laboratories and Research
Jefferson, AR 72079 New York State Department of Health
501-543-7008 Box 509
Fax: 501-543-7662 Empire State Plaza - Room E208
Albany, NY 12201-0509
Pfaffip Leber 518-473-4378
Project Coordinator Fax: 518-486-1505
The Goodyear Tire and Rubber Company
142 Goodyear Boulevard
Akron, OH 44305
216-796-1046
Fax: 216-796-3304
John Moore
President
Institute for Evaluating Health Risks
1101 Vermont Avenue, NW - Suite 608
Washington, DC 20005
202-289-8721
Fax:202-289-8530
James Olson
Department of Pharmacology and
Therapeutics
State University of New York
102 Farbcr Hall
Buffelo,NY 14214
716-829-2319
Fax:716-829-2801
Stephen Safe
Professor
Department of Veterinary Physiology and
Pharmacology
Texas A & M University
Highway 60 - VMA Bunding
College Station, TX 77843-4466
409-845-5988
Fax: 409-862-4929
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APPENDIX B
AGENDA
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U.S. Environmental Protection Agency
TECHNICAL REVIEW WORKSHOP ON THE REFERENCE DOSE (RtD)
FOR AROCLOR 1016
Barceto Washington Hotel
Washington, DC
May 24-25,1994
AGENDA
Co-Chairs
Dr. Mari.Golub
California Environmental Protection Agency
University of California - Davis
Dr. Thomas Burbacher
School of Public Health and
Community Medicine
University of Washington
Dr. Nancy Kim
Division of Environmental Health Assessment
New York State Department of Health
TUESDAY, MAY 24
7:30AM Registration and Onsite Check-in
8-.30AM Welcome
Dr. Dorothy Patton
Risk Assessment Forum
U.S. Environmental Protection Agency
Introduction/Workshop Structure
Dr. Golub
Effects Issues
Chain Dr. Burbacher
8:45 AM Summary of Comments
9:OOAM Panel Discussion
10:15 AM BREAK
10:30AM Panel Discussion (continued)
12:15PM Wrap Up
(over)
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TUESDAY, MAY 24 (continued)
12:30PM LUNCH
Exposure Issues
Chain Dr. Kim
1:45PM Summary of Comments
2:OOPM Panel Discussion
3:30PM Wrap Up
3:45PM BREAK
4:OOPM Observer Comments
5:OOPM Adjourn
WEDNESDAY, MAY 25
Uncertainty Factor Issues
Chain Dr. Golnb
8:OOAM Summary of Comments
8:15AM Panel Discussion
10:OOAM Wrap Up
10:15AM BREAK
10:30AM Workshop Panel Recommendations to EPA
Dr. Golub
12:OONOON Adjourn
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APPENDIX C
CHARGE TO REVIEWERS
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CHARGE TO REVIEWERS
FOR THE RfD FOR AROCLOR 1016
As described in the background section, EPA's RfD/RfC work
group collects and evaluates a broad range of information in
preparing an analysis for each reference dose, focussing on
principal studies, endpoint selection, uncertainty factors, and
weight of evidence analysis. In all cases, a range of
information exists and the RfD is ultimately a product of
scientific judgment. The issue for,the peer review is whether
the RfD for Aroclor 1016 is based on a scientifically responsible
analysis that represents full consideration of the available data
and clear articulation of that analysis in the RfD entry on IRIS.
This charge has two parts. The first part invites highly
specific comments on the major elements of the RfD entry
(Attachment 1) . The second part asks peer reviewers to consider
four broad options as potential recommendations to the RfD work
group.
Note: -The RfD analysis was completed in December 1992. For this
reason, references and analysis do not include research published
after that date. See Part II, Option D.
NOTE: For your information, the RfD/RfC work group and the Risk
Assessment Forum .are separate•agency organizations. When
questions were raised about the RfD entry for Aroclor 1016,
senior agency management asked the Risk Assessment Forum staff to
organize an independent technical review. The Forum will collect
reviewer comments and workshop recommendations and conclusions,
and make these materials available to the RfD/RfC work group,
senior agency management, and the public. This charge was
prepared by the RAF staff based on materials prepared or supplied
by RfD/RfC work group members.
jfc
Part I. Comments. While EPA invites comment on any and all
technical aspects of the RfD entry for Aroclor 1016, we are
particularly interested in comments and analysis on the four
major elements.in the RfD for Aroclor 1016.
Selection of Principal Study
Typically, EPA's RfD/RfC .work group bases an RfD on a single
experimental value, the NOAEL or the LOAEL, derived from a single
"principal" toxicity study. The study designated as the
principal study will usually have the lowest NOAEL and/or lowest
LOAEL among all the studies evaluated. In addition, the
principal study must be of sufficient quality, clearly identify
effects observed at the NOAEL and LOAEL, and must be supported by
the weight of evidence of the entire data base.
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1. The principal study used for the Aroclor 1016 RfD was
published as four periodic reports on a single group of
rhesus monkey mothers and their offspring, including
follow-up data for up to four years after birth. The
four reports (Barsotti and van Millar, 1984; Levin et
al. 1988; Schantz et al; 1989; Schantz et al; 1991),
were all drawn from Dr. Barsotti's doctoral
dissertation and each was published in the peer review
literature.
2. The principal study has not been corroborated in a
second non-human primate (NHP) species. However, the.
RfD work group concluded that evidence of adverse
health effects observed in the rhesus monkeys in this
study was consistent with data from certain studies >in
other species including macaque monkeys, pastel mink,
rats, and humans.
3. The authors of the principal study, as well as various
independent analyses, have identified several factors
that have led to questions about the principal study.
These factors include: low level Aroclor 1048
contamination of the diet; small and variable treatment
group sizes; control animals held under laboratory
conditions for longer time periods than the treated
animals; exclusion of the lowest dose group from
published reports because'of PBB contamination of the
feed; questions about conformity with GLP standards.
4. The RfD workgroup evaluated the principal study in
terms of each of these factors, including'additional
data analysis, and concluded that these.factors did not
disqualify use of these reports as the principal study.
These considerations are described in-the RfD meeting
notes.
Please review Attachment l*and comment on selection and use of
the four reports listed above as the primary basis for the RfD
for Aroclor 1016, including the relevance of other studies, .
questions raised about the principal study, and any other
considerations bearing on the scientific reliability of this
study for this purpose.
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Selection of Critical Effects
Observations in the rhesus monkeys used in the principal study
and in other species demonstrate that pre-natal exposure to PCBs
may affect many organ systems.
1. Reduced birth weight in the rhesus monkeys in the
principal study was identified as the critical effect
for the RfD, and postnatal neurobehavioral effects and
transient dermal pigmentation attributed to Aroclor
1016 exposure were also considered.
2. Endpoints observed in other studies included chloracne,
dermal pigmentation/ facial edema -and biochemical
changes in the central nervous system in monkeys;
adrenal effects in rats, immunologic effects in mice,
and reproductive effects in mink. Although this
information was regarded as consistent evidence of PCB
effects, none of these effects was used as the basis
for the RfD.
3. The RfD workgroup considered the confounding factors
listed above (see page 2) and concluded that these
factors did not compromise the data on reduced birth
weight in these animals.
4. Certain human studies show comparable effects in the
offspring of women exposed to PCB mixtures
occupationally or from eating PCB-contaminated fish.
This is consistent qualitatively with the animal
studies on the general question of PCB exposure, but is
not specific for Aroclor 1016.
Please review Attachment 1 and comment on selection of low birth
weight as the critical effect for the Aroclor 1016 RfD, along
with information on postnatal neurobehavioral effects.
Selection of Uncertainty Factors
When the Agency develops an RfD, it first considers whether there
is a minimum data base available. If only a minimum data base (a
single well conducted subchronic study that only defines a LOAEL)
is available, the Agency considers five area of uncertainty and
quantitatively accounts for them. These areas of uncertainty
include interspecies extrapolation (UFA), intraspecies
extrapolation (UFH), database deficiencies (UFD), subchronic to
chronic exposure extrapolation (UFS), and LOAEL to NOAEL
extrapolation (UFL) . An explanation of how the Work Group
quantitatively accounted for uncertainty in the Aroclor 1016
database is included below.
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1. The RfD workgroup practice is to evaluate five full
areas of uncertainty that are assigned a factor of 10
unless other data suggest a factor less than 10
(usually 1 or 3).
2. For Aroclor 1016, the RfD/RfC.Work Group used four
areas of uncertainty for interspecies extrapolation
(UF;J , intraspecies extrapolation (UFH), database
deficiencies (UFD), and subchronic to chronic exposure
.extrapolation (UFS) . For each UF application the
available information warranted the use of a factor of
less than 10.
• UFA = 3 - Similarity of NHP to human in general,
and specifically metabolism of PCBs and response
to PCB (chloracne, developmental toxicity,
neurobehavioral effects) warrant use of half-log
UF.
• UFH = 3 - Transplacental exposure of infants to
PCB indicate sensitive subpopulation. Appropriate
use of NHP as principal study argue for less than
10.
• UFD = 3 - An extensive database for both human
exposure and animal studies is available.
However/ since specific studies relating to male
reproductive effects and two-generation
reproductive studies were not available, a half-
log factor was used. Also, it is expected that
PCBs will cause the same reproductive effects in
humans.
• UFS = 3 - A true chronic exposure study was not
conducted in monkeys, although the duration of
exposure was considered much greater than
subchronic and long-term latent effects were
observed. The mothers were probably dosed to
"steady state" and were exposed for all of
gestation. It is apparent from the human data
that the developmental effects are most likely the
most sensitive critical effect and the
availability of a chronic duration study would not
necessarily provide a more sensitive NOAEL.
Therefore, a total of less than 10 is warranted.
3. Total UF = 100 is lower than average when compared to
other RfD files examined by the Work Group. This
addresses the overall strength of the file, confidence
in the file and assuredness in identification of a
dose-response for the most sensitive endpoint in a most
relevant species, rhesus monkeys. The RfD work group
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concluded that the identified deficiencies of the
principal study are offset by the weight of evidence of
the supporting data.
Please review Attachment 1 and comment on the uncertainty factor
analysis for Aroclor 1016.
Weight of Evidence Conclusions
The RfD for Aroclor 1016 is based on evaluation of several lines
of animal and human evidence.
Primary Evidence Used for the RfD
1. The NHP study provides conclusive data that the reduced
birth weight of infants and neurobehavioral effects is
consistent with effects observed in other species
including the human. Birth weight has also been
affected in mink; behavioral effects have been noted in
rodents.
2. The developmental and neurobehavioral effects in the
NHP are considered most predictive of effects in
humans, although methodological considerations
precluded using the neurobehavioral effects and
transient dermal pigmentation as co-critical.
Secondary Evidence
1. In another NHP study with Aroclor 1016, investigators
have reported a change in dopamine concentration in
different brain regions.
2. Chloracne and pigmentation have been observed in both
NHP and humans.
3. Mink have also been demonstrated to have an adverse
developmental effect (decreased fetal birth weight and
reduced litter size) following Aroclor 1016 exposure.
4. In vitro metabolism of several PCB congeners is similar
for NHP and humans.
Evidence less consistent with the RfP conclusions
1. There is difficulty in assessing human response-
exposure to a mixture of congeners. Additionally, the
chlorination profile is difficult to characterize both
in human exposures and in environmentally occurring
mixtures.
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2. The developmental toxicity and neurobehavioral effects
are not well characterized in rodent species. However,
the NHP is judged to be a better predictor of human
effects as demonstrated by the quantitative data of the
principal study 'and the qualitative observations of
humans. The behavioral effects were not chosen as
critical given the biphasic nature of the response and
the lack of statistical power in measuring differences
to controls.
Please review Attachment 1 and comment on the weight of evidence
analysis.
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Part II. Recommendations. A range of recommendations might
arise from the peer review. We are interested in your
recommendation as to four broad options.
1. Option A^ Confirm the Aroclor 1016 RfD value as
presented in the IRIS entry, with minor refinements in
the text as recommended during this peer review.
2. Option B. Confirm the Aroclor 1016 RfD value as
presented in the IRIS entry, but revise the text to
include a more comprehensive analysis of data
limitations and related uncertainties.
3. Option C. Revise the Aroclor 1016 RfD value and
accompanying analysis in line with peer review
recommendations.
4. Option D. Any other suggestions, including suggestions
regarding information published after the RfD was
entered on IRIS in December .1992.
Please identify your preferred option, highlighting the primary
considerations influencing your choice, along with, any
recommended changes.
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APPENDIX D
BACKGROUND INFORMATION FOR TECHNICAL REVIEWERS
D-l
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Background Information
Reference Dose/Reference Concentration (RfD/RfC). An RfD
or. RfC is based on the assumption that thresholds exist for
certain toxic effects, e.g., cellular necrosis, but may not exist
for other toxic effects e.g., carcinogenicity. Generally, an RfD
or RfC is an estimate (with uncertainty spanning perhaps an order
of magnitude) of a daily exposure to the human population
(including sensitive subgroups) that is likely to be without an
appreciable risk of deleterious effects during a lifetime.
Accompanying the RfD or RfC are statements on uncertainty and
EPA's confidence in the RfD or RfC and in the underlying data.
RfD/RfC Work Group. The purpose of the RfD/RfC Work Group
is to reach consensus on oral RfDs or inhalation RfCs for
noncancer chronic human health effects developed by or in support
of program offices and the regions. The work group also works to
resolve inconsistent RfDs/RfCs among program offices and to
identify, discuss, and resolve generic issues associated with
methods used to estimate RfDs/RfCs.
Scientists from a mix of pertinent disciplines are selected
by executive appointment from all major Agency program and
regional offices. In addition, scientists from ATSDR and FDA are
invited to work group meetings as observers to assist the Agency
in the information gathering process.
The RfD/RfC Work Group usually meet every other month for
two days. Substances are discussed at the request of any Agency
office or region. The requesting office generally prepares a
file that consists of a summary sheet, a copy of the critical
study, and supporting documentation.
The work group meets to review the file and determines if
the substance-specific summary is adequate. Work group consensus
must be reached on each RfD or RfC. (Note: Consensus generally
means that no member office is aware either of information that
would conflict with the RfD or RfC, or of analyses that would
suggest a different value that is more credible.) Once unanimous
consensus is reached, the substance-specific summary for the RfD
or RfC is .prepared for inclusion on IRIS.
In some cases, the work group agrees that adequate
information is not available to derive an RfD or RfC. A message
is then put on IRIS, which states that the work group reviewed
the specific substance and determined that the health effects
data for the substance were inadequate for derivation of an RfD
or RfC.
Scope of the Technical Review. Although any discussion of
EPA's RfD program presents several generic issues, the May
technical review meeting is sharply focused on the science-based
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- 2 -
information and analyses relevant to Aroclor 1016. Several
limitations are important.
First, the technical review of the Aroclor 1016 RfD entry
focuses on scientific and technical issues for that chemical
only. Larger issues regarding the generic RfD process" are being
addressed by the Agency as a separate effort (58 FR 11490;
February 25, 1993).
Second, while we would welcome consensus, the issues are
complex and EPA does not expect the technical reviewers to reach
consensus on all issues raised in the workshop. Rather, the
purpose of this workshop is to collect expert opinions and
recommendations on reasonable approaches to some difficult and
potentially controversial scientific issues.
Finally, EPA does not expect to resolve all uncertainties in
the data and methods associated with the RfD for Aroclor 1016.
However, with the help of the technical reviewers, EPA expects to
identify the most important areas of uncertainty, useful options
for addressing the uncertainties, and the expected impacts of
these uncertainties on the RfD entry.
IRIS. The Integrated Risk Information System (IRIS) data
base, developed by the U.S. EPA, contains Agency consensus
positions on the potential adverse human health effects of
approximately 500 specific substances. IRIS is the Agency's^
primary vehicle for communication of this information following
comprehensive review by intra-Agency work groups. EPA developed
IRIS for Agency staff in response to a growing need for
consistent risk information on chemical substances for use in
decision-making and regulatory activities.
NOTE: For further information, refer to the attached IRIS
Fact Sheet.
RfD File. A public file is maintained on each IRIS entry
and is available for inspection in Cincinnati. Documents
contained in the file may include but are not limited to the RfD
entry, the principal study as identified in the IRIS summary
sheet and other supporting toxicological studies, and final work
group meeting notes.
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Integrated
System
The Integrated Risk Information System (IRIS) data base,
developed by the U.S. Environmental Protection Agency (EPA), is
EPA's primary vehicle for communication of chronic non-cancer
and cancer health hazard information for over 500 substances. This
information is summary in nature, representing Agency consensus
positions following comprehensive review by intra-Agency work
groups. IRIS is a resource that points the user to the underlying
human and/or animal data used to support the Agency's position.
The system contains hazard identification and dose-response
information, but does not include exposure assessment informa-
tion. The data in IRIS, combined with specific exposure informa-
tion, can be used to help characterize the public health risks of a
given situation. This risk characterization can then serve as input
for a risk management decision designed to protect public health.
IRIS users are cautioned that quantitative risk estimates are
subject to varying degrees of uncertainty and that the existence of
such uncertainty* should be taken into account in preparing site
specific risk analyses. While the data base is updated monthly to
reflect intra-Agency work group decisions, in some cases new
health hazard data may have been generated on a particular
substance since an on-line file was reviewed by the work groups.
These data may not yet be reflected on the system, and should be
considered in developing risk characterizations.
For more information on IRIS and access, contact:
Risk Information Hotline (Staffed by Labat-Anderson Inc.)
Environmental Criteria and Assessment Office
Office of Research and Development
U.S. Environmental Protection Agency
26 West Martin Luther King Drive
Cincinnati, Ohio 45268 USA
Telephone: (513)569-7254 FAX: (513)569-7159
Office of Health and Environmental Assessment
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0462
Aroclor 1016; CASES 12674-11-2 (11/01/93)
Health risk assessment information on a chemical is included in IRIS only
after a comprehensive review of chronic toxieity data by work groups composed
of U.S. EPA scientists from several Program Offices. The summaries presented
in Sections I and II represent a consensus reached in the review process. The
other sections contain U.S. EPA information which is specific to a particular
EPA program and has been subject to review procedures prescribed by that
Program Office. The regulatory actions in Section IV may not be based on the
most current risk assessment, or may, be based on a current, but unreviewed,
risk assessment, and may take into account factors other than health effects
(e.g., treatment technology). When considering the use of regulatory action
data for a particular situation, note the date of the regulatory action, the
date of the most recent risk assessment relating to that action, and whether
technological factors were considered. Background information and explan-
ations of the methods used to derive the values given in IRIS are provided in
the five Background Documents in Service Code 5, which correspond to Sections
I through V of the chemical files.
STATUS OF DATA FOR Aroclor 1016
File On-Line 01/01/93
Category (section) Status Last Revised
Oral RfD Assessment (I.A.) on-line 11/01/93
Inhalation RfC Assessment (I.B.) no data
Carcinogenic!ty Assessment (II.) no data
Drinking Water Health Advisories (III.A.) no data
U.S. EPA Regulatory Actions (IV.) no data
Supplementary Data (V.) no data
.1. CHRONIC HEALTH HAZARD ASSESSMENTS FOR NONCARCINOGENIC EFFECTS
I .A. REFERENCE DOSE FOR CHRONIC ORAL EXPOSURE (RfD)
Substance Name -- Aroclor 1016
CASRN -- 12674-11-2
Last Revised -- 11/01/93
The Reference Dose (RfD) is based on the assumption that thresholds exist for
certain toxic effects such as cellular necrosis, but may not exist for other
toxic effects such as carcinogenic!ty. In general, the RfD is an estimate
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(with uncertainty sparging perhaps an order of magnitude; of a daily exposure
to the human population (including sensitive subgroups) that is likely to be
without an appreciable risk of deleterious effects during a lifetime. Please
refer to Background Document 1 in Service Code 5 for an elaboration of these
concepts. RfDs can also be derived for the noncarcinogenic health effects of
compounds which are also carcinogens. Therefore, it is essential to refer' to
other sources of information concerning the carcinogenicity of this substance.
If the U.S. EPA has evaluated this substance for potential human carcinogen-
icity, a summary of that evaluation will be contained in Section II of this
file when a review of that evaluation is completed.
NOTE: A peer review of the non-cancer oral reference dose for Aroclor 1016,
to determine the adequacy of the studies underlying the reference dose for use
in risk assessments or otherwise, has been tentatively scheduled for December
1993.
I.A.I. ORAL RfD SUMMARY
Critical Effect Experimental Doses* UF MF RfD
Reduced birth weights NOAEL: 0.25 ppm in feed 100 1 7E-5
(0.007 mg/kg-day) mg/kg-day
Monkey Reproductive
Bioassay LOAEL: 1 ppm in feed
(0.028 mg/kg-day)
Barsotti and van Miller,
1984; Levin et al., 1988;
Schantz et al., 1989, 1991
^Conversion Factors: Dams received a total average intake of 4.52 mg/kg (0.25
ppm) or 18.41 mg/kg (1 ppm) throughout the 21.8-month (654 days) dosing •
period. These doses are equivalent to 0.007 mg/kg-day and 0.028 mg/kg-day for
the identified NOAEL and LOAEL respectively.
I .A. 2. PRINCIPAL AND SUPPORTING STUDIES (ORAL RfD)
Barsotti, D.A. and J.P. van Miller. 1984. Accumulation of a commercial
polychlorinated biphenyl mixture (Aroclor 1016) in adult rhesus monkeys and
their nursing infants. Toxicology. 30: 31-44.
Levin, E.D., S.L. Schantz and R.E Bowman. 1988. Delayed spatial alternation
deficits resulting from perinatal PCB exposure in monkeys. Arch. Toxicol.
62: 267-273.
Schantz, S.L., E.D. Levin, R.E. Bowman et al. 1989. Effects of perinatal FCB
exposure on discrimination-reversal learning in monkeys. Neurotoxicol.
Teratol. 11: 243-250.
Schantz, S.L., E.D. Levin and R.E. Bowman. 1991. Long-term neurobehavioral
effects of perinatal polychlorinated biphenyl (PCB) exposure in monkeys.
Environ. Toxicol. Chem. 10: 747-756.
These are a series of reports that evaluated perinatal toxicity and long-
term neurobehavioral effects of Aroclor 1016 in the same groups of infant
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monkeys. Aroclor 1016 is a commercial mixture of polyclorinated biphenyls
(FCBs) devoid of chlorinated dibenzofurans (Barsotti and van Miller, 1984).
Analysis of the commercial feed used for this study revealed contamination
with congeners specific for Aroclor 1248, present in the parts per billion
range. These congeners were present in the control as well as test diets.
Aroclor 1016 was administered to groups of 8 adult female rhesus monkeys via
diet in concentrations of 0, 0,25 or 1.0 ppm for approximately 22 months.
Based on a reported total Aroclor intake of 4.52 and 18.41 mg/kg over the 22-
month exposure period (Schantz et al., 1989, 1991), the low- and high-doses
are estimated to be 0-.007 and 0.028 mg/kg-day, respectively. Exposure began 7
months prior to breeding and continued until offspring were weaned at age 4
months. No exposure-related effects on maternal food intake, general
appearance, hematology, serum chemistry (SGFT, lipid, and cholesterol
analyses) or number of breedings were observed (Barsotti and van Miller,
1984). All monkeys had uncomplicated pregnancies, carried their infants to
term and delivered viable offspring. Teratologic examinations were not
performed. Mean birth weights of the infants in the control, 0.007 and 0.028
mg/kg-day dose groups were 521 g, 491 g and 442 g, respectively (Barsotti and
van Miller, 1984). The decrease in birth weight in the high-dose group was
significantly (p<0.01) lower than in controls. Further statistical analysis
of the infant birth weight data by the Agency indicated that gestation length
did not significantly affect birth weight and the distribution of male and
female infants in the various dose groups could not account for the difference
in birth weights among the dose groups. Agency reanalysis of the data
confirmed the significant decrease in body weight for the high-dose infants,
although slightly different average values were obtained. Males that had
sired some infants were exposed to Aroclor 1248, so the birth weight data were
also analyzed excluding these infants. The results for this adjusted data
indicated that control infants weighed 528 g, low-dose infants weighed 486 g,
and high-dose infants weighed 421 g. Even with this adjustment there was
still a significant difference (p<0.01) in birth weight for the high-dose
group when compared with controls. No significant differences between
treatment and control groups were detected in -neonatal head circumference or
crown-to-rump measurements. Both exposure groups showed consistent weight
gains, but infant weights in the high-dose group were still lower (864 g) at
weaning, although not significantly different from the controls (896 g).
Hyperpigmentation was present at birth in the low- and high-dose infants but
did not persist once dosing was stopped. This clinical change was determined
not to be a critical adverse effect. The concentration of Aroclor 1016 in
breast milk was higher than the maternal dose. No exposure-related
bematologic effects were observed in the infants during the nursing period
(Barsotti and van Miller, 1984)'. One of the offspring in the high-dose group
went into shock and died on the day following weaning for unknown reasons
(Schantz et al., 1989, 1991).
Behavioral testing of the infant monkeys was first performed at age 14
months and no overt signs of PCB toxicity were observed (Schantz et al., 1989,
1991) . Two-choice discrimination-reversal learning was assessed using simple
left-right spatial position, color and shape discrimination problems, with and
without irrelevant color and shape cues. One of the offspring in the low-dose
group stopped responding early in testing for an unknown reason and could not
be induced to resume; therefore, test results were obtained using 6, 7 and 6
infants in the control, low- and high-dose groups, respectively. The
offspring in the high-dose (0.028 mg/kg-day) group were significantly (p<0.05)
impaired in their ability to learn the spatial position discrimination problem
(i.e., achieved 9 correct choices in 10 trials), requiring more than 2.5 times
as many trials as their age-matched controls. There were no significant
learning differences between these groups on this problem during overtraining
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(ability to achieve greater than or equal to 90% corre*._ choices in two
consecutive daily sessions) or position reversals. The only other exposure-
related effect was significantly facilitated learning ability (p<0.05) on the
shape discrimination problem at 0.028 mg/kg-day.
Performance on delayed spatial alternation (a spatial learning and memory
task) was assessed in the offspring monkeys at age 4-6 years (Levin et al.,
1988; Schantz et al., 1991). The two Arodor-exposed groups were not
significantly different from controls (p<0.05) in test performance. However,
the exposed groups did significantly (p<0.05) differ from each other. The
difference between the two exposed groups was due to a combination of
facilitated performance at the low-dose (0.007 mg/kg-day) and impaired
performance at the high-dose (0.028 mg/kg-day). Although these data are
insufficient for establishing an exposure-effect relation due to the lack of
difference between exposed and control groups, the investigators; suggested
that the performance deficit at 0.028 mg/kg-day may have been exposure-
related. The investigators noticed that a paradoxical biphasic effect
occurred on the same test when comparing low-dose and high-dose infants. This
sane effect has been observed for lead-exposed monkeys.
To summarize the above, adult monkeys that ingested 0.007 or 0.028 mg/kg-
day doses of Aroclor 1016 for approximately 22 months showed no evidence of
overt toxicity. Effects occurring in the offspring of these monkeys consisted
of hairline hyperpigmentation at greater than or equal to 0.007 mg/kg-day, and
decreased birth weight and possible neurologic impairment at 0.028 mg/kg-day.
Based on the reduced birth weights of prenatally-exposed monkeys, the 0.007
mg/kg-day dose is the NOAEL and the 0.028 mg/kg-day dose is a LOAEL in
monkeys.
The results of the neurobehavioral tests in the monkey offspring at 14
months and 4-6 years of age indicate adverse learning deficits at the 0.028
mg/kg-day maternal dose. Evaluation of these data is complicated by possible
inconsistencies in the outcome of both the discrimination-reversal learning
tests (learning was impaired and facilitated on different problems) and the
delayed spatial alternation test (performance significantly differed between
the two exposed groups, but not between either test group and the control).
However, there is evidence suggesting that deficits in discrimination-reversal
learning and delayed spatial alternation are related to decreased brain
dopamine (Schantz et al., 1991), which has been observed in monkeys orally
exposed to Aroclor 1016 (Seegal et al., 1990, 1991). Behavioral dysfunctions,
including deficits in visual recognition and short-term memory, also have been
observed in infants of human mothers who consumed fish contaminated with FOB
mixtures of unknown composition (Fein et al., 1984a,b; Jacobsen et al., 1985,
1990; Gladen et al., 1988).
I.A.3. UNCERTAINTY AND MODIFYING FACTORS (ORAL RfD)
UF -- A 3-fold factor is applied to account for sensitive individuals. The
results of these studies, as well as data for human exposure to PCBs, indicate
that infants exposed transplacentally represent a sensitive subpopulation. A
factor of 3 is applied for extrapolation from rhesus monkeys to human. A full
10-fold factor for interspecies extrapolation is not considered necessary
because of similarities in toxic responses and metabolism of PCBs between
monkeys and humans and the general physiologic similarity between these
species. In addition, the rhesus monkey data are predictive of other changes
noted in human studies such as chloracne, hepatic changes, and effects on
-------
reproductive function. A factor of 3 is applied because of limitations in the
data base. Despite the extensive amount of animal laboratory data and human
epidemiologic information regarding FCBs, the issue of male reproductive
effects is not directly addressed and two-generation reproductive studies are
not available. As the study duration was considered as somewhat greater than
subchronic, but less than chronic, a partial factor of 3 is used to account
for extrapolation from a subchronic exposure to a chronic RfD.
MF -- None
I .A.4. ADDITIONAL STUDIES / COMMENTS (ORAL RfD)
Male pig-tailed macaques [Maceca nemistrina], (number not reported, age 3-
7 years, 5-9 kg initial body weight) were administered Aroclor 1016 dissolved
in corn oil on bread in doses of 0, 0.8, 1.6 or 3.2 mg/kg-day for 20 weeks
(Seegal et al., 1991). There were no overt signs of intoxication or exposure-
related effects on body weight gain. Neurochemical analyses of various
regions of the brain were performed following termination of exposure. Dose-
related decreased concentrations of dopamine were observed in the caudate
nucleus, putamen, substantia nigra, and hypothalamus, but not in the globus
pallidus or hippocampus. There were no exposure-related changes in
concentrations of norepinephrine, epinephrine, or serotonin. Other neurologic
endpoints were not evaluated.
Subchronic oral studies of Aroclor 1016 have been performed in species
other than monkeys. These species were tested at doses higher than the 0.007
and 0.028 mg/kg-day doses fed to monkeys in the principal studies.
Groups of 10 female Sprague-Dawley rats (age not reported, body weight
approximately 225-250 g at start) were fed 0, 1, 5 or 50 ppm Aroclor 1016 in
the diet for 5 months (Byrne et al., 1988). The Aroclor was dissolved in
acetone that was evaporated from the diet prior to feeding. Using a. rat food
consumption factor of 0.05 kg food/kg bw (II.S. EPA, 1987), the doses are
estimated to be 0, 0.05, 0.25 and 2.5 mg/kg-day- Serum levels of adrenal
cortical hormones were evaluated four times throughout the treatment period.
Adrenal dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHS)
levels were significantly (p<0.05) reduced at all treatment levels after
approximately 100 days of exposure. Serum corticesterone (the principal
glucocorticoid in rats), adrenal weight, adrenal histology, and nonadrenal
endpoints other than food consumption were not evaluated. Food consumption
did not significantly differ between and among control and treatment groups.
Because insufficient information is available to determine whether the
decreases in circulating adrenal hormones were physiologically significant, it
is uncertain whether the doses are NOAELs or LOAELs for Aroclor 1016 in rats.
Male Balb/c mice (18-20 g body weight) were fed Aroclor 1016 mixed in diet
at concentrations of 0 or 5 ppm for 3 or 6 weeks (Loose et al., 1978). Using
a mouse food consumption factor of 0.13 kg food/kg bw (U.S. EPA, 1987), the
dose is estimated to be 0.65 mg/kg-day. Sensitivity to Salmonella typhosa
endotoxin (15 mice per endotoxin dose) and resistance to infection by
Plasmodium berghei (malaria parasitemia; number of mice not reported) were
evaluated. Sensitivity to the endotoxin was significantly (p<0.05) increased
after 3 weeks of exposure as indicated by endotoxin LD50 values of 152 and 844
ug in the Aroclor-exposed and control groups, respectively. Sensitivity to
the endotoxin after 6 weeks of Aroclor exposure was not evaluated. There were
no significant (p<0.05) effects of Aroclor exposure for 3 or 6 weeks on
-------
malaria lethality as indicated by post-Inoculation sur\./al time, No other
endpoints were evaluated in this study. When injected into neonates, splenic
cells from C57B1/6 male mice exposed to 167 ppm (21.71 mg/kg-day) dietary
Aroclor 1016 for 3 weeks elicited a greater graft-versus-host reaction than
controls (Silkworth and Loose, 1978). Based on the decreased resistance to
infection leading to death, 0.65 mg Aroclor 1016/kg-day suggests a LOAEL for
iraBunotoxicity for subchronic exposure in male mice.
Aulerlch and Ringer (1977) performed a. breeding study in which groups of 8
female and 2 male adult pastel mink were fed diets containing 0 or 2 ppm
Aroclor 1016 for 39 weeks or until the kits were 4 weeks of age. The Aroclor
was dissolved in acetone which was evaporated from the diet prior to feeding.
Using assumed values of 150 g/day for food consumption and 0.8 kg for body
weight for female mink (Bleavins et al., 1980), the estimated dose of Aroclor
1016 is 0.4 mg/kg-day. Monthly determinations showed no statistically
significant differences (p<0.05) between the control and treated mink in body
weight gain, hemoglobin, and hematocrit. Additionally, tabulated data showed
no treatment-related effects on female survival, numbers of females mated,
number of females that gave birth, number of kits born alive or dead, number
of births per female, average birth weight or number of kits alive at 4 weeks.
The evidence for lack of treatment-related effects on body weight, hematology,
reproduction and survival suggests that 0.4 mg/kg-day is a NOAEL for Aroclor
1016 in mink.
Groups of adult Pastel mink were fed a diet containing 0 ppm (24 females
and 6 males) or 20 ppm (12 females and 3 males) Aroclor 1016 during a 247-day
breeding study (Bleavins et al., 1980). Aroclor was dissolved in acetone
which was evaporated from the diet prior to feeding. Using assumed values of
150 g/day for food consumption and 0.8 kg for body weight for female mink
reported by the investigators, the estimated dose of Aroclor 1016 is 3.8
mg/kg-day. There were no deaths in the exposed or control males. Mortality
was higher in the exposed females [25% (3/12) compared with 12.5% (3/24) in
controls], but no clear difference in survival time was observed. Necropsies
for gross abnormalities were performed on all control and treated mink that
died; these showed effects only in the treated mink consisting of emaciation
characterized by an almost complete absence of body fat. Histologic
examinations were not performed. The incidence of mated females giving birth
was reduced in the exposed group [44.4% (4/9) compared with 76.2% (16/21) in
controls], but average-gestation length, live births'and birth weight did not
significantly differ (p>0.05) between exposed and control groups. Body weight
at age 4 weeks, average number of infants per lactating female and infant
biomass (average body weight gain through age four weeks x average number of
infants raised per lactating female) were significantly (p<0.05) reduced in
the exposed group. Mortality during the first 4 weeks of life was increased
in the exposed group [56.0% (14/25) compared with 24.1% (19/79) in controls].
The investigators noted that the adverse effects on reproduction do not appear
to be due to an effect on spermato genes is, since FOB-treated male mink have
had acceptable levels of reproduction when mated to untreated females in other
studies. The evidence for impaired reproduction and increased maternal and
postnatal mortality suggests that 3.8 mg Aroclor 1016/kg-day is an FEL in
mink. Although the FEL from this study and NOEL of 0.4 mg/kg-day from
Aulerich and Ringer (1977) suggest that the dose-severity slope for Aroclor
1016 in mink is steep, neither study tested sufficient numbers of animals or
dose levels to allow'definitive conclusions to be drawn.
Dermal lesions including skin irritation, chloracne and increased
pigmentation of skin and nails have been observed in humans occupationally
exposed to Aroclor 1016 and other Aroclor formulations by both inhalation and
-------
dermal routes (Fischbein et al., 1979, 1982, 1985; Ouw -c al., 1976; Smith et
al.f 1982). However, insufficient data are available to determine possible
contributions of Aroclor 1016 alone, extent of direct skin exposure and
possible contaminants in these occupational studies.
Decreased birth weight has also been reported in infants born to women who
- were occupationally exposed to Aroclor 1016 and other Aroclor formulations
(Taylor et al., 1984, 1989),.ingested PCS-contaminated fish (Fein et al.,
1984a,b) and ingested heated Kanechlor PCBs during the Yusho and Yu-Cheng
incidents (Rogan, 1989; Yamashita, 1977). Due to uncertainties regarding
actual sources of FOB exposure, and other confounding factors and study
limitations, the decreases in human birth weight cannot be solely attributed -
to PCBs, particularly specific PCB mixtures. However, due to the consistency
with which the effect has been observed, the human data are consistent with
the Aroclor 1016-induced decreased birth weight in monkeys reported in the .
principal studies.
The human data available for risk assessment of Aroclor 1016 are useful
only in a qualitative manner. Studies of the general population exposed to
FCBs by consumption of contaminated food, particularly neurobehavioral
evaluations of infants exposed in utero and/or through lactation, have been
reported, but the original PCB mixtures, exposure levels and other details of
exposure are not known (Kreiss et al., 1981; Humphrey, 1983; Fein et al.,
1984a,b; Jacobson et al., 1984a, 1985, 1990a,b; Rogan et al., 1986; Gladen et
al., 1988). Host of the information on health effects of FCB mixtures in
humans is available from studies of occupational exposure. Some of these
studies examined workers who had some occupational exposure to Aroclor 1016,
but in these studies concurrent exposure to other Aroclor mixtures nearly
always occurred, exposure involved dermal as well as inhalation routes (the
relative contribution by each- route was not known), and monitoring data were
lacking or inadequate (Fischbein et al., 1979, 1982, 1985; Fischbein, 1985;
Warshaw et al., 1979; Smith et al., 1982; Lawton et al., 1985).
Information specifically on the oral absorption of Aroclor 1016 is.not
available, but studies of individual congeners and PCB mixtures of higher
chlorine content in animals indicate, in general, that PCBs are readily and
extensively absorbed. These studies have found oral absorption efficiency on
the order of 75 to >90% in rats, mice, monkeys and ferrets (Albro and
Fishbein, 1972; Allen et al., 1974; Tanabe et al., 1981; Bleavins et al.,
1984; Clevenger et al., 1989). A study of a PCB mixture containing 54%
chlorine provides direct evidence of absorption of PCBs in humans after oral
exposure (Buhler et al., 1988), and indirect evidence of oral absorption of
PCBs by humans is available from studies of ingestion of contaminated fish by
the general population (Schwartz et al., 1983; Kuwabara et al., 1979). There
are no quantitative data regarding inhalation absorption of PCBs in humans but
studies of exposed workers suggest that PCBs are well absorbed by the
inhalation and dermal routes (Maroni et al., 1981a,b; Smith et al., 1982;
Wolff, 1985). PCBs distribute preferentially to adipose tissue and
concentrate in human breast milk due to its high fat content (Jacobson et al.,
1984b; Ando et al., 1985).
The metabolism of PCBs following oral and parenteral administration in
animals has been extensively studied and reviewed, but studies in animals
following inhalation or dermal exposure are lacking (Sundstrom and Hutzinger,
1976; Safe, 1980; Sipes and Schnellmann, 1987). Information on metabolism of
PCBs in humans is limited to occupationally exposed individuals whose intake
is derived mainly from inhalation and dermal exposure (Jensen and Sundstrom,
1974; Wolff et al., 1982; Schnellmann et al., 1983; Safe et al., 1985; Fait et
-------
al., 1989). In general, metabolism of PCBs depends on the number and position
of the chlorine atoms on the phenyl rings of the constituent congeners (i.e.,
congener profile of the FOB mixture) and animal species. • Although only
limited data are available on metabolism of PCBs following inhalation
exposure, there is no reason to suspect that PCBs are metabolized differently
by this route.
Data exist on the in vitro hepatic metabolism and in vivo metabolic
clearance of 2,2', 3,3', 6,6' -hexachlorobiphenyl and 4,4'-dichlorobiphenyl
congeners in humans, monkeys, dogs, and rats (Schnellmann et al., 1985). Both
of these congeners are present in Aroclor 1016, but the hexacblorobiphenyl is
only a minor constituent. For each congener, the Vmax values for metabolism
in the monkey, dog and rat are consistent with the respective metabolic
clearance values found in vivo. Thus, the kinetic constants for FOB
metabolism obtained from the dog, monkey, and rat hepatic microsomal
preparations were good predictors of in vivo metabolism and clearance for
these congeners. In investigations directed at determining which species most
accurately predicts the metabolism and disposition of FCBs in humans, the in
vitro metabolism of these congeners was also studied using human liver
microsomes (Schnellmann et al., 1983, 1984). Available data suggest that
metabolism of FCBs in humans most closely resembles that of the monkey and
rat. For example, the in vitro apparent Km and Vmax for humans and monkeys
are comparable. These studies show consistency between the in vitro and in
vivo findings and collectively indicate that metabolism of the two congeners
is similar in monkeys and humans.
I .A. 5. CONFIDENCE IN THE ORAL RfD
Study -- Medium
Data Base -- Medium
RfD -- Medium
Confidence in the critical studies is rated medium since essentially only
one group of monkeys has been examined. The initial study was well conducted
in a, sensitive animal species (rhesus monkeys) that closely resembles humans
for many biological functions. These studies evaluated many sensitive
endpoints of FCB toxicity said the effects observed have also been documented
for human exposure. Many sophisticated reproductive and neurologic tests were
performed over 6 years and many clinical chemistry determinations were
conducted on the dams during the exposure period; Very extensive analyses of-
feed samples and tissue samples from dosed monkeys were performed. Although
contamination of the qontrol laboratory primate diet With FCBs other than
those found in Aroclor 1016 was detected, the level of contamination was at
the level of parts per billion and dosing of Aroclor 1016 was in the parts per
million range. Because the contamination was consistent across all treatment
groups and controls, quantitative comparison of adverse effects can be made.
The investigators carefully documented the levels of test material and
contaminant throughout the exposure and post-exposure period in animal
tissues. Because the system of placentation, hemothelial-chorial with
bidiscoidal distribution, is similar for Rhesus monkeys and humans, it is felt
that toxic events that are induced during gestation for Rhesus monkeys will be
highly predictive.of similar events in humans. Historically, developmental
neurobehavioral effects observed in rhesus monkeys are predictive of similar
effects in humans. Although these studies were performed in an academic
setting prior to the era of Good Laboratory Practices- Quality Control-Quality
Assurance, the study report provides ample documentation of the experimental
-------
protocol and quality o£ data collected. While the group sizes for this study
are small (8 monkeys/group) when compared with the standards for rodent
studies they are within the acceptable range for studies of large mammalian
species as determined by EPA.
The data base for FCBs in general is extensive. Studies examining Aroclor
1016 have been performed in rhesus monkeys, mice, rats and mink. However,
despite the extensive amount of data available only medium confidence can be
placed in the data base at this time. It is acknowledged that mixtures of
FCBs found in the environment do not match the pattern of congeners found in
Aroclor 1016, therefore the RfD is only given medium confidence. For those
particular environmental applications where it is known that Aroclor 1016 is
the only form of FOB contamination, use of this reference dose may rate high
confidence. For all other applications only medium confidence can be given.
The U.S. EFA recognizes that there is a diversity of opinion among scientists
concerning the use of the monkey studies for determining FOB toxicity.
However, all of the studies in the vast data base for this chemical mixture
support the conclusions reached ,in this document.
_I.A.6. EPA DOCUMENTATION AND REVIEW OF THE ORAL RfD
Source Document -- This assessment is not presented in any existing U.S. EPA
document.
Other EPA Documentation -- U.S. EPA, 1980, 1984, 1989, 1990
Agency Work Group Review -- 02/21/90, 03/25/92, 06/23/92, 09/24/92, 10/15/92,
11/04/92, 02/11/93
Verification Date -- 11/04/92
I.A.7. EPA CONTACTS (ORAL RfD)
John L. Cicmanec / OHEA -- (513)569-7481
Michael L. Dourson / OHEA (513)569-7531
I.E. REFERENCE CONCENTRATION FOR CHRONIC INHALATION EXPOSURE (RfC)
Substance Name -- Aroclor 1016
CASRN -- 12674-11-2
Not available at this time.
-------
_II. CARCINOGENICITY ASSESSMENT FOR LIFETIME EXPOSURE
Substance Name -- Aroclor 1016
CASRN -- 12674-11-2
This substance/agent has not: been evaluated by the U.S. EPA for evidence of
human carcinogenic potential.
III. HEALTH HAZARD ASSESSMENTS FOR VARIED EXPOSURE DURATIONS
III .A. DRINKING WATER HEALTH ADVISORIES
Substance Name -- Aroclor 1016
CASRN — 12674-11-2
Not available at this time.
III.B. OTHER ASSESSMENTS
Substance Name -- Aroclor 1016
CASRN — 12674-11-2
Content to be determined.
JD7. U.S. EPA REGULATORY ACTIONS
Substance Name -- Aroclor 1016
CASRN — 12674-11-2
Not available at this time.
_V. SUPPLEMENTARY DATA
Substance Name -- Aroclor 1016
-------
CASRN — 12674-11-2
Not: available at this time.
_VI. BIBLIOGRAPHY
Substance Name -- Aroclor 1016
CASRN -- 12674-11-2 s>
Last Revised -- 02/01/93
VI.A. ORAL RfD REFERENCES
Albro, P.W. and L. Fishbein. 1972. .Intestinal absorption of polychlorinated
biphenyls in rats. Bull. Environ. Contain. Toxicol. 8: 26-31.
Allen, J.R. and D.H. Norback. 1976. Pathobiological responses of primates to
polychlorinated biphenyl exposure. In: Proceedings of the National Conference
on Polychlorinated Biphenyls. EPA 560/6-75-004. p. 43-49.
Allen, J.R., L.J. Abrahamson and D.H. Norback. 1973. Biological effects of
polychlorinated biphenyls and triphenyls on the subhuman primate. Environ.
Res. 6: 344-354.
Allen, J.R., D.H. Norback and I.C. Hsu. 1974. Tissue modifications in
monkeys as related to absorption, distribution, and excretion of
polychlorinated biphenyls. Arch. Environ. Contain. Toxicol. 2: "86-95.
Ando, M., H. Saito and I. Wakisaka. 1985. Transfer of polychlorinated
biphenyls (PCBs) to newborn infants through the placenta and mothers' milk.
Arch. Environ. Contam. Toxicol. 14: 51-57.
Aulerich, R.J. and R.K. Ringer. 1977. Current status of PCB toxicity to
mink, and effect on their reproduction. 'Arch. Environ. Contam. Toxicol. 6:
279-292.,
Barsotti, D.A. 1980. PhD Thesis. "Gross, Clinical, and Reproductive Effects
of Polychorinated Biphenyls in the Rhesus Monkey", August, 1980. Available
through the University Library, University of Wisconsin, Madison, Wisconsin.
Barsotti, D.A. and J.P. Van Miller. 1984. Accumulation of a commercial
polychlorinated biphenyl mixture (Aroclor 1016) in adult rhesus monkeys and
their nursing infants. Toxicology. 3fr: 31-44.
/ .
Barsotti, D.A., R.J. Marlar and J.R. Allen. 1976. Reproductive dysfunction
in rhesus monkeys exposed to low levels of polychlorinated biphenyls (Aroclor
1248). Food Cosmet. Toxicol. 14:99-103.
Becker, G.M., W.P. McNulty and M. Bell. 1979. Polychlorinated biphenyls-
induced morphologic changes in the gastric mucosa of the rhesus monkey.
Lab. Invest. 40: 373-383.
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Bleavins, M.R., R.J. Aulerich and R.K. Ringer. 1980. Polychlorinated
biphenyls (Aroclors 1016 and ,1242): Effects on survival and reproduction in
mink and ferrets. Arch. Environ. Contain. Toxicol. 9: 627-635.
Bleavins, M.R., W.J. Breslin, R.J. Aulerich et al. 1984. Placental and
mammary transfer of a polychlorinated biphenyl mixture (Aroclor 1254) in the
European ferret (Hustela putorius furo). Environ. Toxicol. Cheat. 3: 637-644.
Buhler F., P. Schmidt and C.H. Schlatter. 1988. Kinetics of PCB elimination
in man. Chemosphere. 17: 1717-1726.
Byrne, J.J., J.P. Carbone and M.G. Fepe. 19*88. Suppression of serum adrenal
cortex hormones by chronic low-dose polychlorobiphenyl or polybromobiphenyl
treatments. Arch. Environ.-Con tarn. Toxicol. 17: 47-53.
Clevenger, M.A., S.M. Roberts, D.L. Lattin et al. 1989. The pharmacokinetics
of 2,2',5,5'-tetrachlorobiphenyl and 3,3',4,4'-tetrachlorobiphenyl and its
relationship to toxicity. Toxicol. Appl. Pharmacol. 100: 315-327.
Fait, A., E. Grossman, S. Self et al. 1989. Polychlorinated biphenyl
congeners in adipose tissue lipid and serum of past and present transformer
repair workers and a comparison group. Fund. Appl. Toxicol. 12: 42-55.
Fein, G.G., J.L. Jacobson, S.W. Jacobson et. al. 1984a. Intrauterine exposure
of humans to PCBs: Newborn effects. U.S. Environmental Protection Agency,
Duluth, MN. EPA 600/13-84-060. NTIS PB84-188*887.
Fein, G.G., J.L. Jacobson, S.W. Jacobson et al. 1984b. Prenatal exposure to
polychlorinated biphenyls: Effects on birth'size and gestation age. J.
Pediatr. 105(2): 315-320.
Fischbein-, -A. 1985. Liver function tests in workers with occupational
exposure to polychlorinated biphenyls (PCBs): Comparison with Yusho and Yu-
Cheng. Environ. Health Perspect. 60: 145-150.
Fischbein, A., M.S. Wolff, R. Lilis et al. 1979. Clinical findings among
PCB-exposed capacitor manufacturing workers. Ann. NY Acad. Sci. 320:
703-715.
Fischbein, A., M.S. Wolff, J. Bernstein et al. 1982. Dermatological findings
in capacitor manufacturing workers exposed to dielectric fluids' containing
polychlorinated biphenyls (PCBs). Arch. Environ. Health. 37: 69-74.
Fischbein, A., J.N. Rizzo, S.J. Solomon et al. 1985. Oculodermatological
findings in workers with occupational exposure to polychlorinated biphenyls
(PCBs). Br. J. Ind. Med. 42: 426-430.
Gladen, B.C., W.J. Rogan, P. Hardy et al. 1988. Development after exposure
to polychlorinated biphenyls and dichlorodiphenyl dichloroethene
transplacentally and through human milk. J. Pediatr. 113(6): 991-995.
Humphrey, H.E.B. 1983. Population studies of PCBs in Michigan residents.
In; PCBs:-Human and Environmental Hazards, F.M. D'ltri, M. Kamriii, Ed.
Butterworth, Boston, MA. p. 299-310.
Jacobson, J.L., S.W. Jacobson, P.M. Schwartz et al. 1984a. Prenatal exposure
to an environmental toxin: A test of the multiple effects model. Dev. •
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Psycho. 20(4): 523-5~~.
Jacobson, J.L., 6.G. Fein, S.W. Jacobson et al. 1984b. The transfer of
polychlorinated biphenyls (FCBs) and polybrominated biphenyls (PBBs) across
the human placenta and into maternal milk. Am. J. Public Health. 74: *
378-379.
Jacobson, S.W., G.G. Fein, J.L. Jacobson et al. 1985. The effect of
intrauterine PCB exposure on visual recognition memory. Child Dev. 56:
853-860.
Jacobson, J.L., S.W. Jacobson and H.E.B. Humphrey. 1990a. Effects of in
utero exposure to polychlorinated-biphenyls and related contaminants on
cognitive functioning in young children. J. Pediatr. 116(1): 38-45.
Jacobson, J.L., S.W. Jacobson and H.E.B. Humphrey. 1990b. Effects of
exposure to PCBs and related compounds on growth and activity in children.
Neurotoxicol. Teratol. 12: 319-326.
Jensen, S. and G. Sundstrom. 1974. Structures and levels of most
chlorobiphenyls in two technical PCB products and in human adipose tissue.
Ambio. 3: 70-76. - .
Kreiss, K., M.M. Zack, R.D. Kimbrough et al. 1981. Association of blood
pressure and polychlorinated biphenyl levels. J. Am. tied. Assoc. 245(24):
2505-2509.
Kuwabara, K., T. Yakushiji, I. Watanabe et al. 1979. Increase in the human
blood PCB levels promptly following ingestion of fish containing PCBs. Bull.
Environ. Contam. Toxicol. 21: 273-278..
Lawton, R.W., M.R. Ross, J. Feingold et al. 1985. Effects of PCB exposure on
biochemical and hematological findings in capacitor workers. Environ. Health
Perspect. 60: 165-184.
Levin, E.D., S.L. Schantz and R.E. Bowman. 1988. Delayed spatial alternation
deficits resulting from perinatal PCB exposure in monkeys. Arch. Toxicol.
62: 267-273.
Loose, L.D., J.B. Silkworth, K.A. Pittman et al. 1978. Impaired host
resistance to endotoxin and malaria in polychlorinated biphenyl- and
hexachlorobenzene-treated mice. Infect. Immun. 20: 30-35.
Maroni, M., A. Colombi, G. Arbosti et al. 1981a. Occupational exposure to
polychlorinated biphenyls in electrical workers. II. Health effects. Br. J.
Ind. Med. 38: 55-60.
Maroni, M., A. Colombi, S. Cantoni et al. 1981b. Occupational exposure to
polychlorinated biphenyls in electrical workers. I. Environmental and blood
polychlorinated biphenyls concentrations. Br. J. Ind. Med. 38: 49-54.
Ouw, H.K., G.R. Simpson and D.S. Siyali. 1976. Use and health effects of
Aroclor 1242, a polychlorinated biphenyl in an electrical industry. Arch.
Environ. Health. 31: 189-194.
Rogan, W.J. 1989. Yu-Cheng, Chapter 14. In: Halogenated Biphenyls,
Terphenyls, Naphthalenes, Dibenzodioxins and Related Products, 2nd ed., R.D.
Kimbrough and A.A. Jensen, Ed. Elsevier Science Publishers, Amsterdam.
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p. 401-415.
Rogan, W.J., B.C. Gladen, J.D. McKInney et al. 1986. Neonatal effects'of
transplacental exposure to PCBs and DDE. J. Pediatr. 109(2): 335-341.
Safe, S. 1980. Metabolism, uptake, storage and bi.oaccumulati.on. In:
Halogenated BIphenyls, Terphenyls, Naphthalenes, Dibenzodioxins and Related
Products, R.D.Kimbrough, Ed. Elsevier Science Publishers, Amsterdam, p. 81-
107.
Safe, S., S. Bandiera, T. Sawyer et al. 1985. PCBs: Structure-function
relationships and mechanism of action. Environ. Health Perspect. 60: 47-56.
Schantz, S.L., E.D. Levin, R.E. Bowman et al. 1989. Effects of perinatal PCB
exposure on discrimination-reversal learning in monkeys. Neurotox. Teratol.
11: 243-250.
Schantz, S.L., E.D. Levin and R.E. Bowman. 1991. Long-term neurobehavioral
effects of perinatal polychlorinated biphenyl (PCB) exposure in monkeys.
Environ. Toxicol. Chem. 10(6): 747-756.
Schnellmann, R.G., C.W. Putnam and 1.6. Sipes. 1983. Metabolism of
2,2',3,3',6,6'-hexachlorobiphenyl and 2,2',4,4',5,5'-hexachlorobiphenyl by
human hepatic microsomes. Biochem. Pharmacol. 32: 3233-3239.
Schnellmann, R.G., R.F. Volp, C.W. Putnam and 1.6. Sipes. 1984. The
hydroxylation, dechlorination and glucuronidation of 4,4'-dichlorobiphenyl by
human hepatic microsomes. Biochem. Pharmacol. 33: 3503-3509.
Schnellmann, R.G., E.M. Vickers and 1.6: Sipes. 1985. Metabolism and
disposition of polychlorinated biphenyls. In: Reviews in Biochemical
Toxicology, Vol. 7, E.Hodgson, J.R. Bend and R.M.< Philpot, Ed. Elsevier
Press, Amsterdam, p. 247-282.
Schwartz, P.M., S.W. Jacobson, G. Fein et al. 1983. Lake Michigan fish
consumption as a source of polychlorinated biphenyls in human cord serum,
maternal serum, and milk. Am. J. Public Health. 73: 293-296.
Seegal, R.F., B. Bush and W. Shain. 1990. Lightly chlorinated 0-substituted
PCB congeners decrease dopamine in nonhuman primate brain and in tissue
culture. Toxicol. Appl. Pharmacol. 106(1): 136-144.
Seegal, R.F., B. Bush and K.O. Brosch. 1991. Comparison of effects of
Aroclor 1016 and Aroclor 1260 on non-human primate catecholamine function.
Toxicol. 66(2): 145-164.
Silkworth, J.B. and L.D. Loose. 1978. Cell mediated immunity in mice fed
either Aroclor 1016 or hexachlorobenzene. Toxicol. Appl. Pharmacol. 45: 326.
(Abstract)
Sipes, I.J. and R.G. Schnellmann. 1987. Biotransformation of PCBs metabolic
pathways and mechanisms. In: Polychlorinated Biphenyls (PCBs): Mammalian and
Environmental Toxicology, S. Safe, Ed. Environmental Toxic Series, Vol. 1.
Springer Verlag New York, Inc., Secaucus, NJ. p. 98-110.
Smith, A.B., J. Schloemer, L.K. Lowry et al. 1982. Metabolic and health
consequences of occupational exposure to polychlorinated biphenyls. Br. J.
Ind. Med.. 39: 361-369.
-------
Sundstrom, G. and 0. Hutzinger. 1976. The metabolism of chlorobiphenvls: A
review; Chemosphere. 5: 267-298.
Tanabe, S., Y. Nakagawa and R. Tatsukawa. 1981. Absorption efficiency and
biological half-life of individual chlorobiphenyls in rats treated with
Kanechlor products. Agric. Bipl. Chem. 45: 717-726.
Taylor, P.R., C.E. Lawrence, H.L. Hwang et al. 1984. Polychlorinated
biphenyls: Influence on birthweight and gestation. Am. J. Public Health. 74:
1153-1154.
Taylor, P.R., J.M. Stelma and C.E. Lawrence. 1989. The relation of
polychlorinated biphenyls to birth weight and gestational age in the offspring
of occupationally exposed mothers. Am. J. Epidemiol. 129: 395-406.
Tryphonas, L., S. Charbonneau, H. Tryphonas et al. 1986a. Comparative
aspects of Aroclor 1254 toxicity in adult cynomolgus and rhesus monkeys: A
pilot study. Arch. Environ. Contain. Toxicol. 15: 159-169.
Tryphonas, L., D.L. Arnold, Z. Zawidzka et al. 1986b. A pilot study in adult
rhesus monkeys (M. mulatta) treated with Aroclor 1254 for two years. Toxicol.
Pathol. 14: 1-10.
U.S. EPA. 1980. Ambient Water Quality Criteria Document for Polychlorinated
Biphenyls. Prepared by the Office of Health and Environmental Assessment,
Environmental Criteria and Assessment Office, Cincinnati, OH for the Office of
Water Regulations and Standards, Washington, DC. EPA 440/5-80/068. NTIS
PB81-117798/AS.
U.S. EPA. 1984. Health Effects Assessment for Polychlorinated Biphenyls.
Prepared by the Office of Health and Environmental Assessment, Environmental
Criteria and Assessment Office, Cincinnati, OH for the Office of Solid Waste
and Emergency and Response, Washington, DC.
U.S. EPA. 1987. Recommendations for and Documentation of Biological Values
for Use in Risk Assessment. Prepared by the Office of Health and
Environmental Assessment, Environmental Criteria and Assessment Office,
Cincinnati, OH for the Office of Solid Waste and Emergency Response,
Washington, DC. EPA 600/6-87/008. NTIS PB88-179874/AS.
U.S. EPA. 1989. Ambient Water Quality Criteria Document Addendum for
Polychlorinated Biphenyls. Prepared by the Office of Health and Environmental
Assessment, Environmental Criteria and'Assessment Office,, Cincinnati, OH for
the Office of Water Regulations and Standards, Washington, DC.
U.S. EPA. 1990. Drinking Water Criteria Document for Polychlorinated
Biphenyls (PCBs) (Final). Prepared by the Office of Health and Environmental
Assessment, Environmental Criteria and Assessment Office, Cincinnati, OH for
the Office of Drinking Water, Washington, DC.
Warshaw, R., A. Fischbein, J. Thornton et al. 1979. Decrease in vital
capacity in PCB-exposed workers in a capacitor manufacturing facility. Ann.
NY Acad. Sci. 320: 277-283.
Wolff, M.S. 1985. Occupational exposure to polychlorinated biphenyls (PCBs).
Environ. Health Perspect. 60: 133-138.
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Wolff, M.S., J. Thornton, A. Fisehbein et al. 1982. disposition of
polychlorinated biphenyl congeners in occupationally 'exposed persons.
Toxicol. Appl. Fharmacol. 62: 294-306.
Ynraashita, F. 1977. Clinical features of polychlorobiphenyls (FOB)-induced
fetopathy. Pediatrician. 6: 20-27.
VLB. INHALATION RfD REFERENCES
None
VI.C. CARCINOGENICITY ASSESSMENT REFERENCES
None
VI.D. DRINKING WATER HA REFERENCES
None
_VII. REVISION HISTORY
Substance Name -- Aroclor 1016
CASRN -- 12674-11-2
Date
Section Description
08/01/91 I.A. Oral RfD now under review
08/01/92 I.A. Work group review dates added
10/01/92 I.A. Work group review date added
12/01/92 I.A. Work group review dates added
01/01/93 I.A. Oral RfD assessment on-line
01/01/93 VI .A. Oral RfD references on-line
02/01/93 VI.A. Oral RfD references corrected
03/01/93 I.A.6. Work group review date added
09/01/93 I.A. Oral RfD noted as going to be externally peer reviewed
11/01/93 I.A. Note revised
-------
SXNONYMS
Substance Name -- Aroclor 1016
CASRN -- 12674-11-2
Last Revised -- 01/01/93
12674-11-2
AROCLOR 1016
HSDB 6352
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W*TI6 STATES ENVIRONMEHTJOT^ROTECnON AGENCY
WASHMOTON.B.CL tMOO
JAN 12 633
efrccoF
Mr. Stephen B. Hamilton, Jr.
Manager, Environmental Science and Technology
General Electric Company
3135 Easton Turnpike
Fairfield, CT 06431
Dear Mr.
I am writing to follow op with you regarding issues raised at oar meeting of
January 6, 1993, where we discussed the Environmental Protection Agency's (EPA)
Reference Dose (RfD) for Aroclor 1016. As 1 indicated to yon at the meeting, we
share your concern in assuring flu: the RfD for Aroclor 1016 is based on sound
aa'roce. Considering the issues raised at the meeting, I believe that a peer review of
these data would be appropriate.
Ih&ve asked ORD't Risk Assessment Forum to conduct this peer review in fee
Bear future. The peer review will focus on the Wisconsin primate data on which the
calculation of the RfD for Aroclor 1016 was primarily based, and will also examine
other data relevant to this RfD as it appears on the Integrated Risk Information System
(IRIS), as well as the background documents. Any additional information thai you
might be able to provide to fl»e Agency relevant to the RfD for Aroclor 1016 win be
appreciated. Ibis information and any questions you might have should be directed to
Dr. Dorothy Panon, Director of tfae Risk Assessment Forum, at (202) 260-6743.
Sincerely yours,
Erich W. Bretthaoer *
'Assistant Administrator
for Research and Development
CR F. Henry Habichtn
William Fariaad
Dorothy Patson
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I UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
^ OFFICE OF RESEARCH AND DEVELOPMENT
ENVIRONMENTAL CRITERIA AND ASSESSMENT OFFICE
CINCINNATI. OHIO 45268
January 28, 1993
MEMORANDUM
SUBJECT: Change in NOAEL for Aroclor 1016 from verified
Concentration
FROM: John L. Cicmanec, D.V.M. ClJ 9 fj^^^^J—*
RfD/Rf C Work Group Member %rWr< ^ v
TO: RfD/RfC Work Group
During the process of final editorial review of the Aroclor
1016 file, just before it was loaded onto IRIS, Gary Foureman
discovered that we had erroneously transposed the dosage of 0.008
mg/kg-day as the NOAEL dose instead of the correct value of 0.007
mg/kg-day. The 0.008 mg/kg-day is used in the earliest published
paper of the series of key references Barsotti, D.A. and Van
Miller, J. P. "Accumulation of a commercial polychlorinated
biphenyl mixture (Aroclor 1016) in adult rhesus monkeys and their
nursing infants", Toxicology 30:31-44, 1984. The correction to £he
value of 0.007 mg/kg-day was made in the Schantz paper, Schantz,
S. L., Levin, E. D., Bowman, R. E., Heironimus, M. P., and
Laughlin, N. K., "Effects of perinatal PCB exposure on
discrimination-reversal learning in monkeys", Neurotox. and
Teratol. 11:243-250, 1988. The change resulted from the
investigators taking a second, more critical, look at the actual
dosing information.
This matter is being brought to the attention of the entire
Work Group for the purpose of providing formal documentation of the
change as it will appear in the meeting notes.
Printed on Recycled Paper
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04/O4/92 13; 50 9202 280 0393
VSBPA. ORD-OHEA
ECAO-CIN
Po*t-ft™ brand fax transmits! memo 7671 |*ot
jr—- J a_lLUlBM^ y^__L——
Co.
Co.
put
July SO. 1992
Mr. F. Henry Habkht. H
Deputy Administrator
U. S, Environmental Protection Agency
401 M Street SW
Washington, DC 80460
Dear Hank:
We understand mat EPA is considering establishing a non-cancer reference
dose (Rfd) for PCB Arodor 1016 in the IRIS database in August or September.
Currently, no Rfd exists for non-cancer effects and EPA's standard setting and
risk assessment is driven solely by the cancer risk attributed to PCBs by EPA.
GE's scientists tell me that this new Rfd would in most instances result in
clean up standards for PCBs which are even more stringent than those
currently established using cancer toadcity as the primary risk driver.
35fe-3?e concerned that adding a non-cancer Rfd to IRIS iiTw-considered •
(^grematurc'and ask that you have your staff reconsider this propogedracSon. la
ttuTTegard, we request a meeting with you and appropriate members of your
staff to outline our specific concerns before EPA takes any action:
Summarized below are some of die numerous factors which militate in favor, of
much more careful consideration by EPA:
• The Administrator has told us that a comprehensive reassessment of
hontJECBs are regulated js underway. Indeed, that reassessment appears
to be progressing at a deliberate but slow pace considering the
convincing nature of new evidence on PCB cancer toxicity. The
mtroductionjzf-a-non-cancer Rfd during the interim appears to defeat
and predetermine the outcome of the comprehensive
reassessment. Moreover, the speed with which this is occurring
contrasts with the much slower pace of the general PCB reassessment,
You have directed a thorough review of how the IRIS process can be
improved. None of die process changes now being considered by the
Agency, e.g. public participation, peer review and better expressions of
uncertainties, were used in establishing the proposed Rfd for PCBs. It is
antithetical to your attempt to open the IRIS process to hurriedly create
an Rfd for PCBs, which is one of the mosfiSentifically controversial
and environmentally ubiquitous chemical^Tbefbre the process
improvements you seek are implemented.
• You have also directed a shift away from single-number risk as*
to a broader approach of risk management that considers the
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08/04/92 13:51 9202 260 0393 USEPA ORD-OHEA •»-»* ECAO-CIN Qj 002/002
uncertainties of t^hg scientific information available and a variety of
exposure scenarios. A single number R£d reverts the regulatory
approach for PCBs back to policy by the numbers and will remit in die
risk assessment process not talcing into account more real world, actual
risks.
• The animal studies that will be relied upon for the Aroclor 1016 Rfd and
other PCB Rfds have been criticized in the scrennfic community. As
stated above, the process used in this instance allowed little opportunity
. for a thorough and open review. In addition) die Agency has no
guidelines for measuring many of the health effects that would be
considered for other Aroclor Rfds, e.g. unmunotoxieny. These effects
should not be measured and translated into IRIS standards until there is
scientific agreement on the measurements and die real concerns raised
by the criticisms of the studies have been resolved. Zh short, what is die.
rush here?
• Finally the proposed Rfd would be inconsistent with risk standards set
by other agencies, e.g. FDA. We are unaware of any significant
interagency coordination on this issue.
Hank, I believe that top EPA management attention to this important Agency
action is warranted to Insure that good science is translated into good policy.
I have asked Dr. Steve Hamilton of my staff to meet as soon as possible with
Erich Bretthauer on the science issues. I will call you shortly to set a meeting
date for us to «fiy"« the science as well as the policy implications.
Stephen D. Ramsey
SDE^an
CK 1L Bretthauer
R» Guhnond
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tmal Baric Ctrnptfr
eptember 3,1992
Dr. F. Henry Habichtn
Deputy Administrator
U.S. Environmental Protection Agency
401M Street SW
Washington, DC 20460
Dear Hank
I wanted to follow-up my fetter to you of July "30,1992 concerning EPA'* plans to
establish a new non-cancer reference dose (RfD) for PCB Arodor 1016. Members
of Erich Bretthauer's staff met with Dr. Steve Hamilton and Me. Marion
Kerrington of my ttaff on August 20. While the meeting was informative and
candid, and much appreciated by us, we continue to be very concerned with the
Agency's plans to establish the RfD in the IRIS database at a time when
revaluation of the IRIS process is ongoing but has not yet been completed. This
is particularly the case when, the data and studies upon which this action will be
based are seriously flawed. Because this issue is so important to GE, to EPA and
to the public/1 ask mat before a final.decision is reached, we have an opportunity
to meet with you to give you our reasons why a decision at this time would be
premature and ill-adviaed. I've summarized our concerns below.
As we understand it, EPA is planning to establish a reference dose (RfD) of 8 X10
(-5) mg/kg/day for Arodor 1016 based on reproductive studies in rhesus
monkeys carried out by Drs. James Allen, D. Barsotti and colleagues at the
University of Wisconsin - Madison in the 1970s. At the meeting of August 20,
Dr. Hamilton outlined seven examples of known dosing and/or cross
contamination problems that demonstrate the unreliable nature of the chemical
handling and dose administration practices that were employed in those studies.
Chemicals involved in these studies included various Arodor PCB mixtures,
polybrominated biphenyls and TCDD. For example, one third of the test group
receiving Arodor 1016 had to be dropped from the published account of jus
work because the animals received polybrominated biphenyls as well as PCB.
The remaining test population, as well as some of the controls, also received
tome level of Arodor 1248, the Arodor mixture containing the highest
tration of TCDD equivalents. As a result of mis attts-contamination,
•trong peaks were observed in the gas chromatograms from tissue samples of the
Arodor 1016 study representing "dloxin-like" congeners that are not present in
1016. We believe that the presence of these congeners can account for the
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X/1C/S2 17:04 t*202 200.
anomalous diojdn-like toxic effects and the reproductive effects observed an me
offspring of the test animals. Alternatively, one cannot rule out the presence of
dloxln, itself, possibly resulting; from cross-contamination from a concurrenitty
run experiment.
In addition, PCBs quantitated as Arodor 1016 were found In tissue sample* taken
from five of 8 randomly selected animals before the experiment b^gftt.
Therefor^, we maintain that it is impossible to determine from these tacts the
identity of the tcodcantCfi) or the dose at which an effect was observed. A
reference dose based upon such data would be meaningless.
Members of your, staff indicated that they were familiar with scene of the
problems that we described, but had discounted their significance. Part of their
reasoning was that the reference dose calculated for 1016 was similar to mat
calculated for Arodor 1248 based on work by the same investigators. Since the
1248 study suffered from similar quality problems as the 1016 study, a similar
result is not surprising and certainly does not justify the use of bad data. We
obviously strenuously disagree about the significance of these flaww in the ways
the studies were conducted. Many tosdcologists who are familiar with the field of
halogenated hydrocarbon toxicological research know about the problems with
the rhesus monkey studies carried out at the University of Wisconsin in me
1970s. Several notable scientists have expressed their disbelief on learning that
EPA plans to use this work as a basis for. quantitative risk assessment
Aside from the suspect quality of the data, we are also concerned about the
approach the Agency has proposed to take in applying uncertainty factors to
derive the KID for Arodor 1016. At the August 20 meeting, we learned for the
first time of the assumptions to be used to account for uncertainties associated
with the primate studies. Serious questions arise about the appropriateness of
using certain of these safety factors that we would like to discuss further with
your staff before any deqp^" ie made to finalize the proposed Arodor 1016 RfD.
I find it very disturbing mat the plan to establish the 1016 RfD is occurring at a.
time when the IRIS process is undergoing review to determine how it cart be
improved through public participation, peer review and other mechanisms that
wfll ensure an open and thorough review of the effects of chemical substances.
Given the amount of criticism the scientific community has leveled against me
University of Wisconsin studies, it is especially troubling that the Agency is
moving forward with establishment of the 1016 RfD before, review of the IRIS
process has been completed.
Ac you are aware, once EPA establishes a reference dose for PCBs, If: will be
virtually impossible to alter it. States will follow EPA's lead in theiir risk
assessment approaches. It will become a regulatory totem which will be virtually
rnitouchable. This decision is going to drive very costly dean-up and compliance
decisions which win result in the expenditures of millions and perhaps billions
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of dollars by American companies. Great care must be taken to make sure such a
decision is the right one, based on unquestionable science, not rushed to decision
on a Sawed record.
Given the importance of tjhe establishment of this RfD to the regulated
community/ the apparent Impasse in discussions between GE and EPA scientists
on substantial scientific issues and EPA's plans for improving me DOS review
process, I request mat EPA place the establishment of me RfD lor Arodor 1016 on
hold until a thorough review of PCS risk science can be completed and presented
to EPA's Science Advisory Board.
Finally, on a related matter, my staff was told that the requested re-evaluation of
cancer potency factors for PCBs, based on the data from the re-read of the Ever
tumor slides performed by the Institute for Evaluating Health Risks QEHR), is
not going forward. Dr. Dorotibiy Cantor, an assistant to Don Clay, acknowledged
in a meeting in February, 1992 involving GE and Region H mat EPA considers
the re-read to be of high quality, the result of a process overseen, by EPA and
other government scientists. Administrator Reilly has on several occasions told
G.E.'s Chairman that such a review was in fact underway. We would appreciate
knowing the status of the Agency's evaluation of PCBs. If no such review is to be
performed, it is even more alarming to us that EPA would move rapidly to
develop a non-cancer reference dose based on low quality data while not moving
forward with an evaluation of cancer potency factors which is based on high
quality data.
I understand mat the EPA staff will consider further the scientific
reviewed by us and that the earliest entry of the Arodor RfD into the IRIS data
base is now October 1, 1992. I plan to be out of the country until the first week in
October. If you feel you must proceed with the October 1 entry, I request that you
meet with members of my staff in my absence. The optimum time for me to
meet with you is October 15 or 16 in Washington.
Mr. Larry Boggs of my staff wfflbe contacting you regarding a meeting tune,
ly yours,
SDR/bJb
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10 Little Britain Road
Newburgh.N.Y. 12550
•(914)569-8010 PAX (914) 562-5271 •
JAMES B. BACON DAVID S. BBRNZ
October 15, 1992
Williaa S. Reilly, Administrator
USX 2?A
410 Main Street. li.W.
BOOB 1200 / West Tower
Washington/ D.C. 20460
Ret S-uperfund review of PCB contamination in the Hudson
River.
Dear NT. Rsilly,
Z writ* to urge you to have EPA's Environmental
Criteria and Assessment Office proaulgate a Reference Dose
Value for the non-carcinogenic health effects of PCBs as
soon as possible. This number must be assigned in time to
be included in the current reassessment of the PCB problem
in the Hudson River by EPA Region 2.
As you know, the General Electric Company baa been
identified as the responsible party for the federal Hudson
River PCB suparfund site which is on the national priorities
list. Throughout, G-E. has attempted to manipulate the
reassessment process and now seeks to avoid inclusion of the
non-cancer risks of FCBs in the ongoing reassessment. Z am
particularly disturbed by G.E's exertion of political
influence over the SPA reassessment far outside the
legitimate processes provided for expressing its concerns.
No doubt, C.B. hopes to avoid liability by delaying or
weakening the reassessment process until a flood or other
event spreads the PCB hot-spats and makes a clean-up
impracticable. G.&.'s back-door influence is unconscionable
and must: not be allowed to prevent EPA from doing its job.
Tha public interest requires inclusion of the non-cancer
risks in EPA's assessment as many people continue to a»t
fish caught in the Hudson River.
Furthermore, If 6.2. is permitted to exert undue
influence to escape liability here, it will only make EPA's
job more difficult when attempting to hold G-E. and
responsible parties accountable elsewhere.
As an attorney with some limited experience in
environmental lav, I am keenly aware of the complexity of
the issues involved when dealing with the liability of a
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large company for a toxic clean-up.' Yet the public
deserves, and the lav provide* for a PCS clean-up of the
Hudson River paid for by the responsible party. Anything
you can do to expedite this will be greatly appreciated by
»any.
Thanks, in advance for your time and consideration.
Yours truly,
David Bernz, Esql
cc: Hon. Hamilton Fish, Meaber of Congress
Hudson River Sloop Clearwater, Inc.
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aber 28, 1992
William Reilly, Administrator
USA SPA
410 Hain St. N.W.
Ra. 1200, West Tower
Washington, D.c. 20460
Dear Mr. Reilly:
We, the undersigned, include organizations and individuals
•who have maintained a long-standing commitment to the remediation
of the PCS problem that plagues the Hudson River* We are writing
to you at this time to express our extreme concern regarding 'Che
efforts of the General Electric Co. (G.B.) to influence BPA's
superfund review of this site.
As you know, G.E. has been identified as the responsible
party for the federal Hudson River FCB 'superfund site which, is on
the National Priorities list. It has now come to our attention
that 6.2. is attempting to exert pressure on the federal EPA -in
an effort to derail the promulgation of a numerical value
(Reference Dose Value or RfD) for the non-carcinogenic health
effects of PGBs by EPA's Environmental Criteria and Assessment
Office (ECAO).
At this tine, the EPA Region 2 office is in the midst of the
second phase of a Remedial Investigation/Feasibility study for
this site, which- includes a human health risk assessment. Region
|0
2 has indicated that it intends to include non-carcinogenic
-------
toacicities of FCBs in its assessment, providing that ECAO is able
to provide a numerical value before .the review La completed.
dearly/ it is in G.B. *c interest to delay ECAO approval of
an RfD for PCBs, in an attest to prevent thin information from
being factored into the decision for the Hudson River Super fund
site. However, it is clearly not in the public's interest that
sound scientific information which is critical to this decision
be omitted. Further, because FCBs are the tenth most common
contaminant at federal Superfund sites, and the priority
pollutant: at 185 sites, the negative implications of G.B. *s
actions are far reaching.
It is of utmost importance that SPA not deviate from its
normal procedures for promulgation and incorporation of a
toxioity value into the Integrated Risk information System (IRIS)
database. If 6.5. has legitimate questions or concerns regarding
the numerical value SPA derives, federal regulations (Federal
Register Vol. 53, No. 106, 6/2/88) provide a clear process
through, which the concerns of outside parties-can be raised and
evaluated, and an appropriate response made.
A report by the U.S. Off ice .of Technology Assessment
("Coming clean, Superfund Problems Can Be Solved", 1989)
criticized EPA for allowing responsible parties to influence
Superfund decisions. G.E, which is responsible for over 5O
federal Superfund sites, acre than any other corporate polluter,
-------
been particularly aggressive in reeking to influence publc
opinion, elected officials, public agencies, the press and the
scientific community in relation to toe Hudson River FOB
Suparfund site.
For over 20 years, the Hudson River and people along its
snores have suffered the impact* of extensive PCS contamination.
We urge SPA to act without further delay, to adopt a value for
the non-cancerous health effects of PCBs, so that EPA's ultimate
decision on the Hudson River can be one based on sound science
and responsible public policy.
Bridget Barclay
Hudson River sloop dearwater. Inc.
Sarah Clark
Environmental Defense Fund
Derry Bennett
American Littoral Society
Lee Wasseman
Environmental Planning Lobby
Jane NcgaJci
N.J. Environmental Federation
Ann Raba
Citizens Environmental Coalition
Sincerely,
Cara Lee
Scenic Hudson, Inc.
Leona Hoodes
Orange Environment
Sarah Meyland
Citizens Campaign
David Killer
National Audubon Society
Tom Lake
Fisherman
Cindy Zipf..
Clean ocean Action
Sarah Chasis
Natural Resources Defense Council
Bamabus KcHenry
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cos CongrMSVcoan Hita Lovey
Congressnan Hanilton Fiih, . tTr.
Congretfaxian George Hochbrueckner
Senator Daniel P. Xoynihan
HYS Attorney General Robert Abrams
NYS Acsenblyman Maxtric« Hlnch«y
NYS A0s«atblyman George Pataki
H2S Senator Hary Goodbne
Congrecsaan Matthew HCBagh
Xhonas Jorling, Conaissioner of Enviroraa«ntal conservation
Dr. Andrew Carlson/ NYS Dept. of Health
SPA .Region 2
Eric Bretthauer, Assistant Administrator, EPA Office of
Sesearch and Development
F. Henry Habiclit, EPA Deputy administrator
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON. D.C. 20460
OFFICE OF
RESEARCH AND DEVELOPMENT
May 25, 1990
SUBJECT: RfD Meeting - February 21, 1990
FROM:
Vr"Of f ice of Teqgnology Transfer and Regulatory Support
TO: RfD Work Group
-------
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Chemical Name* Aroclor 1016 (Oral) Date: 02/21/90
CAS#: 12674-11-2
Office: OTTRS/ODW
Previously Verified: No
Previous Discussion Dates: None.
Outstanding Issues: None
1. Documentation:
Adequate. However, ODW questioned the usefulness of RfDs for
individual Arochlors as their occurrence in the environment is
as a mixture. OTTRS noted Region 5 requested an RfD for this
specific Arochlor (Attachment #5). OHEA noted the lack of a
multigeneration study as a gap in the data base.
2. Study:
Appropriate. HERL pointed out that there was a lower dose
group which was not included in the study description. OTTRS
was asked to obtain these data (Allen work).
3. Uncertainty Factor: Appropriate
4. Modifying Factor: None
5. Calculation: Correct
6. Confidence Statement: Not discussed
7. Are the old issues resolved: None
8. Outstanding issues:
The work group is considering whether RfDs should be written
for individual Arochlors.
9. Additional work:
OTTRS was asked to include the Allen work, check the CRAVE
meeting notes for the Arochlor discussion, and talk to the
regions about Arochlor mixtures in the field. ODW was asked
to write-up their position and show comparable toxicity data
for other Arochlors for the work group to consider.
-------
10. New Status: The RfD for Arochlor 1016 is
ON IRIS: NOT ON IRIS:
No change to IRIS (IR) , Verified (V)
Pending change to IRIS (RE) X Under Review (UR)
Withdraw and new RfD __, Not Verified (NV)
Verified (WV)
Withdraw and Still
Under Review (WR)
New Verification Date:
-------
I.A. REFERENCE DOSE FOR CHRONIC ORAL EXPOSURE (RfDoV
Substance Name — Aroclor 1016
CASRN -- 12674-11-2
Preparation Date — 01/20/90
I.A.I. ORAL RfO SUMMARY
Critical Effect •• Experimental Doses* UF MF RfD
Reduced birth weight NOEL: 0.25 ppm diet 100 1 1E-4
(approx. 0.01 mg/kg mg/kg/day
Monkey Reproductive bw/day)
Bloassay
LOAEL: 1.0 ppm diet
Barsottl and van {approx. 0.04 mg/kg
Miller, 1984 bw/day)
•Conversion Factors: Dietary concentrations were converted to mg/kg bw/day
dose rates by assuming that the pregnant monkeys consumed 4.2% of their body
weight per day on average.
__I.A.2. PRINCIPAL AND SUPPORTING STUDIES (ORAL RfD)
Barsottl, D.A. and J.P. van Miller. 1984. Accumulation of a commercial
polychlorlnated blphenyl mixture (Aroclor 1016) 1n adult rhesus monkeys and
their nursing Infants. Toxicology. 30: 31-44.
In animals, Aroclor 1016 given 1n the diet to 24 female rhesus monkeys
for 87 plus or minus 9 weeks at 0, 0.25 or 1.0 ppm (8 animals/group) evoked
no aim'* tarn ties of clinical, gross or reproductive parameters 1n the
were bred, conceived and experienced uncomplicated
birth weight of Infants 1n the control, 0.25 and 1.0 ppm
groups were SiS >J«s or minus 64, 491 plus or minus 24, and 422 plus or minus
29 g, respectively. The high-dose birth weight was significantly smaller
than control (p<0.01). No significant differences between experimental and
control groups were detected In neonatal head circumference or crown to rump
measurements. Both experimental groups showed consistent weight gains, but
at weanling, Infant weights from the high-dose group remained lower (although
not statistically so). This study demonstrated a NOEL of 0.25 ppm and a
LOAEL of 1.0 ppm.
In humans. YamashHa (1977) reported four cases of Infants born to
mothers who had Yusho during pregnancy. The amount of PCB-cantamlnated oil
consumed during pregnancy was approximately 1.1-10.5 L. Maternal symptoms
Included acneform eruptions, folllcular accentuation; dark orown pigmentation
on the skin, mucous membranes and nails; and hypersecretlon of the me1 bom1 an
gland. Three of the four Infants, Including one full-term (40 weeks
gestation), one premature (36 weeks, gestation), and one 2 weeks later than
term (42 weeks gestation), were small-for-gestat1onal age (both weight and
1158R -1- 01/19/90
-------
height). Other clinical features among the four Infants Included dark brown
pigmentation on the Skin and mucous, membranes, glng' 1 hyperplasla, eruption
of teeth at birth, spotted calcification on the parleio-ocdpUal skull and
the large or wide fontanels and sagittal suture, facial edema and
exophthalmic eyes.
Kuratsune et al. (1969) summarized four studies of 10 live and 3
stillborn births from February 15 to January 31, 1968, to 11 females with
Yusho during pregnancy and 2 wives of males with Yusho during the female's
pregnancy. The amount of Kanechlor-contaminated oil consumed during
pregnancy was 0.3-2.6 L (Yamaguchl et al., 1971). Of 10 live and 2 stillborn
births. 9 had unusually grayish, dark-brown stained skin, 5 had similar
pigmentation of the glnglva and nails and most had Increased eye discharge
(Yamaguchl et al., 1971; Takl et al., 1969; Funatsu et al., 1971). Of the 13
Infants, 12 were described as smaller than the national Japanese standards
and 4 as small-for-dates babies {Yamaguchl et al., 1971; Tak1 et al., 1969).
A study of Individuals who consumed moderate quantities of
PCB-contamlnated lake fish Indicated that PCBs crossed the placenta. PCB
exposure, as measured by both contaminated fish consumption and cord serum
PCB levels, predicted lower birth weight and smaller head circumference of
Infants born to these mothers (Fein et al., 1984).
High PCB serum levels were found In some women who had recent or former
missed abortions with mean PCB serum levels of 103.04, 82.00 and 20.69 ppb
for recent missed abortions, former missed abortions and control groups.
respectively {Bercovld et al., 1983). Some women with premature delivery
had mean PCB serum levels of 128 ppb 1n the premature delivery group vs. 26.5
ppb In the 'control group (Uasserman et al., 1982). The higher PCB serum
levels were associated with Increased Incomplete abortions (Bercovlcl et al..
1983) and premature deliveries (Wasserman et al.. 1982),' but a definitive
causal relationship cannot be established, as only small numbers of women
were examined {up to 17 symptomatic; up to 10 asymptomatic), and some of
these women had high serum levels of some organochloHne Insecticides (DOT
Isomers and their metabolites, llndane, dleldrln, heptachlor epoxlde).
The effects discussed In these human studies are almost certainly evoked
by dUf*r«nt PCBs (Indeed the Japanese studies were reporting on the Yusho
}&cl«*»i 4*tch was also caused 1n part by exposure to polychlorlnated
dtt>*n/«t *>***). However, a consistent finding among these human studies Is a
reduced birth weight. While not definitive In their own right, these human
studies Indirectly support the Agency's choice of the critical effect from
the BarsotU and van Miller (1984) study, used as the basis of the RfO.
I.A.3. UNCERTAINTY AND MODIFYING FACTORS (ORAL RfO)
UF s 100. This represents a 10-fold factor to account for sensitive
Individuals and another factor of 10 to account for uncertainties In both
animal to human (about 3-fold) and subchronlc to chronic (about 3-fold). A
full 10-fold factor for animal to human 1s not considered necessary because
of the similarity In metabolism between monkeys and humans (V. supra), and
1158R -2- 01/19/90
-------
the general similarity between these two species. A full 10-fold factor for
subchronlc to chronic Is not considered necessary because of Interim duration
of the exposure 1n the critical study.
MF = 1.
l.A.4. ADDITIONAL COMMENTS (ORAL RfO)
Commercial PCB mixtures vary 1n PCB Isomer and congener composition, and
Impurities. In general, PCB mixtures produce low to moderate acute toxldty
1n mammalian species, but produce pronounced toxldty after short-term,
subchronlc and chronic exposures. In addition, as reported for other
halogenated aromatic hydrocarbons, PCBs exhibit significant Interspedes
variability In toxldty. In considering the health effects of PCBs 1n
.animals. It Is Important to consider the Isomer and congener composition of
the PCBs, potential Impurities, the length of exposure and the species under
Investigation. The data presented 1n this IRIS file refers specifically to
Aroclor 1016 and should not be used for other PCBs without proper analysis.
Aroclor 1016 given 1n the diet to pastel mink of both sexes for 8 months
at 0 (24 females and 6 males) or 20 pom (12 females and 3 males) Induced
emaciation characterized by an almost complete absence of body fat In 3/12
females that died. The 3/24 females that died In the control group did not
exhibit this extreme condition (Bleavlns et a!., 1980). Aroclor also reduced
reproductive performance as only 4/9 females mated produced kits (versus
lfe/?l In control). Aroclor 1016 given In the diet to 8 female and 2 male
•Ink at 2 ppm for 10 months evoked no significant differences In body weight
gain, hemoglobin or packed cell volume. Nor were effects seen on
reproductive parameters, kit growth, or adult or kit mortality (Aulerlch and
Ringer. 1977). These two studies Indicate a range 1n the possible
experimental threshold for the reproductive and developmental toxlclty of
Aroclor 1016 In mink of between 2 and 20 ppm of diet. The dose-severity
slope appears to be steep, however, and neither study tested sufficient
animals 1n order to draw definitive conclusions.
Aroclor 1016 given In the diet to about 15 BALB/CJ male mice for 6 weeks
at 167 ppm Increased the mortalities caused by S. typhosa endotoxln and P.
berghel. but failed to demonstrate hlstopathologlcal changes 1n lung, thymus,
mesenterlc lymph nodes or spleen. Hlstopathologlcal examination of the liver
revealed hepatocytlc hyperplasla (Loose et al., 1978). Aroclor 1016 given 1n
the diet to an unreported number of C57B1/6 male mice for 3 weeks at 167 ppm
elicited a.greater graft versus host response from splenic cells from treated
mice when Injected Into neonates. This Indicates the Aroclor 1016 may
activate donor lymphocytes (Sllkworth and Loose. 1978). These latter two
studies Indicate that Immunologlcal effects are occurring In mice at dietary
concentrations of about 8- or 170-fold higher than concentrations that evoke
reproductive and developmental effects In mink and monkeys, respectively.
In the past 60 years, large numbers of workers have been exposed to PCBs
In the manufacture or use of PCB-contalnlng products; however, evaluation of
any health effects 1s complicated by exposure to other chemicals. Generally
speaking, symptoms associated with PCB exposure do not correlate with
duration and Intensity of exposure In the workplace (U.S. EPA, 1988). For
1158R -3- 01/19/90
-------
example, It appears -that Individual susceptibility to chloracne is more
important than duration and extent of PCB exposure. This data Indicate that
a reduction In the UF for subchronlc to chronic exposure may be appropriate.
Data exists on the In vitro hepatic metabolism and In vivo metabolic
clearance of 2,2',3,3',6,6'-hexa-CB and 4,4'-d1-CB In.humans, monkeys, dogs
and rats (Schnellmann et al., 1985). For each PCB, the Vmax values for
metabolism In the monkey, dog and rat are consistent with the respective
metabolic clearance values generated from 1n vivo studies. Thus, the kinetic
constants for PCB metabolism obtained from the dog, monkey and rat hepatic
mlcrosomal preparations were good predictors of 1n vivo metabolism and
clearance for these PCBs.
In Investigations directed at determining which species most, accurately
predicts the metabolism and disposition of PCBs In humans, the In vitro
metabolism of 2,2',3,3',6,6'-hexa-CB and 4,4'-d1-CB was also Investigated 1n
human liver mlcrosomes (Schnellmann et al., 1983, 1984). Available data
suggest that the human metabolism of PCBs would most closely resemble that of
the monkey and rat, but not the dog. For example, the In vitro apparent Km
(urn) and Vmax (pmoles/nmoles P-450/mln) are comparable between humans and
monkeys with values for the Kms of 2.2',3,3',6,6'-hexa-C8 and 4,4'-dt-C8 of
8.8 and 0.43 In humans and 5.2 and 0.92 1n monkeys, respectively. Values for
Vmax for these two PCBs were 19 and 4.4 In humans as compared to 14 and 4.3
1n monkeys, respectively. In vivo data on the relative persistence of
specific PCBs In humans are also consistent with the above In vitro results
on the metabolism of PCBs.
These metabolism studies collectively Indicate that the monkey Is
comparable to humans for these two PCBs and that In vitro results are
consistent with 1n vivo results. The use of a monkey study as a basis of the
RfO
-------
I.A.b. EPA DOCUMFMTA110N AND REVIEW OF THE ORAL RfD
U.S. EPA. 1988. Drinking Water Criteria Document fot Polychlorlnated
Blphenyls (PCBs). Environmental Criteria and Assessment Office, Cincinnati.
OH. ECAO-C1N-414, April.
Agency RfD Work Group Review: 02/ /SO
Verification Date:
I.A.7. EPA CONTACTS (ORAL RfD)
Michael L. Dourson / ORO .— (513)569-7531 / FTS 684-7531
Krlshan Khanna / ODW —.(202)382-7588 / FTS 382-7588
_VI. REFERENCES
Aulerlch, R.3. and R.K. Ringer. 1977. Current status of PCS toxIcHy to
mink, and effect on their reproduction. Arch. Environ. Contarn. Toxlcol. 6:
279-292.
Barsottl, D.A. and 3.P. van Miller. 1984-. Accumulation of a commercial
polychlorlnated blphenyl mixture (Aroclor 1016) In adult rhesus monkeys and
their nursing Infants. Toxicology. 30: 31-44.
Bercovld, B.. M. Wassermann, S. Cucos, H. Ron. D. Uassermann and A. Pines.
1983. Serum levels of polychlorlnated blphenyls and some organochloMne
Insecticides 1n women with recent and former missed abortions. Environ.
Res. 30(1): 169-174.
Bleavlns. M.R.. R.J. Aulerlch and R.K. Ringer. 1980. Polychlorlnated
blphenyls (Aroclors 1016 and 1242): Effects on survival and reproduction In
mink and ferrets. Arch. Environ. Contam. Toxlcol. 9(5): 627-635.
Fein, G.G., 3.L. Jacobson, S.W. Jacobson, P.M. Schwartz and J.K. Dowler.
1984. Prenatal exposure to polychlorlnated blphenyls: Effects on birth size
and gestatlonal age. 3. Pediatrics. 105: 315-320.
Funatsu, I., et al. 1971. A chloroblphenyls Induced fetopathy. Fukuoka
Acta. Med. 62: 139. (3ap.)
Kuratsune. M.. et al. 1969. An ep1dem1olog1c study on "Yusho" or
chloroblphenyls poisoning. Fukouka Acta Med. 60: 513. (Jap.)
Loose, L.D...K..A. Plttman, K.-F. Benltr, J.B. SUkworth. W. Mueller and F.
Coulston. 1978. Environmental chemical-Induced Immune dysfunction.
Ecotoxlcol. Environ. Saf. 2: 173-198.
1158R -5- 01/19/90
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Schnellmann, R.G., 0 u. Putnam and 1.6. Slpes. 1983. Metabolism of
2.2'.3.31,6.6'-hexachlorob1phenyl and 2,2' ,4.4' .5.5' Hexachloroblphenyl by
human hepatic mlcrosomes. Blochem. Pharmacol. 32:3233-3239.
Schnellmann, R.G., R.F. Volp, C.W. Putnam and I.G. Slpes. 1984.. The
hydroxylatlon, dechlorlnatlon and glucuronldatlon of 4,4'-d1chlorob1phenyl by
human hepatic ralcrosoraes. Blochem. Pharmacol. 33: 3503-3509.
Schnellmann, R.G., E.M. Vlckers and I.G. Slpes. 1985. Metabolism and
disposition of polychlorlnated blphenyls. In: Reviews 1n Biochemical
Toxicology, Vol. 7, E. Hodgson, J.R. Bend and R.M. Phllpot, Ed. Elsevler
Press. Amsterdam, p. 247-282.
Sllkworth, J.B. and L.O. Loose. 1978. Cell mediated Immunity 1n mice fed
either Aroclor 1016 or hexachlorobenzene. Toxlcol. Appl. Pharmacol. 45:
326. (Abstract)
Takl. I., S. Hlsanaga and Y. Amagase. 1969. Report on Yusho
(chloroblphenyls poisoning) pregnant women and their fetuses. Fukuoka Acta.
Med. 60: 471. (Jap.)
Wasserman. M.. H. Ron, B. Bercovlcl. D. Wassermann, S. Cucos and A. Pines.
1982. Premature delivery and organochlorlne compounds: Polychlorlnated
blphenyls and some organochlorlne Insecticides. Environ. Res. 28(1):
106-112.
Yamaguchl, A., T. Yoshlmura and M. Kuratsune. 1971. A survey on pregnant
women and their babies having consumed rice oil contaminated with
chloroblphenyls. Fukuoka Acta Med. 62: 117. (Jap.)
Yamashlta, F. 1977. Clinical features of polychlorblphrenyls (PCB)-lnduced
fetopathy. Paediatrician. 6: 20-27.
1158R -6- 01/19/90
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SUBJECT: RfD/RfC Work Group Meeting—March 24, 25 and 26, 1992
TO: RfD/RfC Work Group
FROM: Annie M. Jarabek
Office of Health and Environmental Assessment
Research Triangle Park, NC
Michael L. Dourson
Office of Health and Environmental Assessment
Cincinnati, OH
NAME
K. Bailey
M. Barren
R. Benson
J. Cicmanec
S. Chou
M. Copley
S. Dapson
B. Davis
M. Dourson
G. Foureman
E. Francis
G. Ghali
L. Hall
R. Hill
L. Ingerman
A. Jarabek
T. McMahon
B. Means
B. Mintz
M. Morris
E. Ohanian
Y. Patel
W. Phang
K. Poirier
J. Risher
S. Rotenberg
S. Segal
P. White
R. Whiting
IN ATTENDANCE WERE:
OFFICE
March 24, 1992
OW
OSW
Region VIII
OHEA/STA
ATSDR
OPP/HED
OPP/HED
OSWER
OHEA/STA
OHEA/HPA
OTTRS/ORD
OPP/HED
HERL/ORD
OPPTS
SRC
OHEA/HPA
OPP/HED
OERR
OW/OST
OW/OST
OW/OST
OW
OPP/HED
OHEA/CMA
Region IV
Region III
Clement
OHEA/EAG
OPP/HED
PHONE
260-5535
260-6977
330-1543
684-7481
236-6037
3O5-7661
260-9493
684-7533
629-1183
260-7891
365-7490
629-2774
260-2897
(315) 426-3405
629-4847
260-2201
260-9569
260-0312
260-7571
260-5849
684-7462
257-1586
597-2842
(703) 934-3768
260-2589
365-5473
-------
Chemical Name: Aroclor 1016 (RfD) Date: 03/25/92
CAS#: 12674-11-2
Office: OHEA/STA
Previous Decision: Under Review
Previous Discussion Dates: 2/21/90
Outstanding Issues: OTTRS to include Allen work and discuss with
the regions which aroclor mixtures are found in the environment.
OST was asked to write-up their position and show comparable
toxicity data for other aroclors.,
1. Documentation:
Sufficient. OHEA/STA distributed a handout (Attachment #11)
on the distribution of PCB congeners in different aroclor
formulations.
2. Rationale:
A series of studies in the same group of monkeys (Barsotti
and van Miller 1984; Levin er al. 1988; Schantz et al. 1989,
1991) were chosen as co-critical studies. In these studies,
the monkeys were exposed to a commercial mixture of aroclor
1016 (containing no chlorinated dibenzofurans) prenatally
and throughout lactation until weaning at 4 months.
Behavioral testing began at 14 months of age (with choice
discrimination-reversal tests) and again at 4-6 years of age
with a delayed spatial alternation test. Reduced birth
weights and learning deficits in offspring that occurred at
a LOAEL of 18.4 mg/kg for 21.8 months (0.028 mg/kg/day) (no
NOAEL established) were identified as the critical effects.
There was a significant difference between the high-dose
group (0.028 mg/kg/day) and the controls in the first
behavioral test conducted at 14 months, and the two treated
groups were significantly different from each other but not
from control in the second behavioral test conducted at 4-6
years.
10
-------
3. Study:
OW noted that they had reservations regarding the analytical
characterization of aroclors, their concerns included (1)
the presence of trace contaminants cannot be ruled out and
(2) the arochlor mixtures present in the environment are
different than those used experimentally. The Work Group
viewed OW concerns as risk characterization issues rather
than issues regarding dose-response.
Hyperpigmentation was observed in the offspring of animals
exposed to both 0.007 mg/kg/day and 0.028 mg/kg/day and this
effect was not considered adverse; however, OHEA/STA
expressed concern with how to handle this effect. The Work
Group agreed with OHEA/STA that the hyperpigmentation at the
low-dose level was of concern, but not considered to be
adverse, especially since the effect was reversible.
Region VIII suggested that the 0.007 mg/kg/day dose level be
called out as a NOAEL and that the critical studies should
be considered developmental studies rather than reproductive
studies.
OHEA/HPA suggested that the low-dose level may be a LOAEL
for learning deficits. The Work Group-was uncomfortable in
interpreting the learning data and suggested that HERL/NTD
review the effects.
4. Uncertainty Factor:
The uncertainty factor will be influenced by the NOAEL/LOAEL
designation and the determination if the critical studies
are developmental studies.
5. Modifying Factor: Not discussed
6. Calculation: Not discussed
7. Confidence Statement: Not discussed
8. Are the old issues resolved: None
9. Outstanding issues:
OHEA/STA to ask HERL/NTD to review the critical studies to
determine if the low-dose level is a LOAEL.
11
-------
10. Additional work:
1) OW was asked to provide OHEA/STA with a statement of.
their concerns about' the characterization of the aroclors.
OHEA/STA was asked to incorporate this statement into the
additional comments section.
2) OW requested that the discussions for each of the
critical studies be better delineated.
3) As discussed in #3.
11. New Status: The RfD for aroclor 1016 is
ON IRIS: NOT ON IRIS:
No change to IRIS (IR) ' Verified (V)
Pending change to IRIS (RE) X Under Review (UR)
Withdraw and new RfD Not Verifiable (NV)
Verified (WV)
Withdraw and Still
Under Review (WR)
New Verification Date: r
12
-------
_I. -CHRONIC HEALTH HAZARD ASSESSMENTS FOR NONCARCINOGENIC EFFECTS
_I.A. REFERENCE DOSE FOR CHRONIC ORAL EXPOSURE (RfD)
Substance Name — Aroclor 1016
CASRN — 12674-11-2
Preparation Date •«- Pending
_I.A.l. ORAL RfD SUMMARY
Critical Effect Experimental Doses* UF MF RfD
Reduced birth weights; NOAEL: None 1000 1 3E-5
Learning deficits in mg/kg/day
offspring LOAEL: 18.4 mg/kg for
21.8 months (0.028 mg/kg/day)
Monkey Reproductive
Bioassay . -
Barsotti and van Miller,
1984; Levin et al., 1988;
Schantz et al., 1989, 1991
*Conversion Factors: Dosage corresponds to a reported total average intake of
4.52 mg/kg bw during an average exposure period of 21.8 months (Schantz et
al., 1989, 1991). Aroclor 1016 was administered as 0.25 ppm in the diet.
_I.A.2. PRINCIPAL AND SUPPORTING STUDIES (ORAL RfD)
Barsotti, D.A. and J.P. van Miller. 1984. Accumulation of a commercial
polychlorinated biphenyl mixture (Aroclor 1016) in adult rhesus monkeys and
their nursing infants. Toxicology. 30: 31-44.
Levin, E.D., S.L. Schantz and R.E Bowman. 1988. Delayed spatial alternation
deficits resulting from perinatal PCB exposure in monkeys. Arch. Toxicol.
62: 267-273.
Schantz, S.L., E.D. Levin, R.E. Bowman et al. 1989. Effects of perinatal PCB
exposure on discrimination-reversal learning in monkeys. Neurotoxicol.
Teratol. 11: 243-250.
Schantz, S.L., E.D. Levin and R.E. Bowman. 1991.. Long-term neurobehavioral
effects of perinatal polychlorinated biphenyl (PCB) exposure in monkeys.
Environ. Toxicol. Chem. 10: 747-756.
These are a series of reports that evaluated perinatal toxicity and
long-term neurobehavioral effects of Aroclor 1016 in the same groups of infant
monkeys. Aroclor 1016 was administered to groups of 8 adult female rhesus
monkeys (body weight not reported) vTa diet in concentrations of 0, 0.25 or
1.0 ppm for 2118+/-2.2 months. The Aroclor 1016 was a commercial mixture found
to be devoid of chlorinated dibenzofurans (Barsotti and van Miller, 1984).
AROCHLOR.RFD -1- 02/11/92
-------
Exposure began 7 months prior to breeding (6 control females and 7 exposed
females per dosage were bred to unexposed males) and continued until offspring
were weaned at age 4 months. Based on a reported total Aroclor intake of
4.52+/-0.56 and 18.41+/-3.64 mg/kg over the 21.8-month exposure period
(Schantz et al., 1989, 1991), the low and high dosages are estimated to be
0.007 and 0.028 mg/kg/day, respectively. No exposure-related effects on
maternal food intake, general appearance, hematology (complete blood counts),
serum chemistry (SGPT, lipid and cholesterol analyses) or number of breedings
were observed (Barsotti and van Miller, 1984). All monkeys had uncomplicated
pregnancies, carried their infants to term and delivered viable offspring. No
teratologic examinations were performed. Mean birth weights of the infants in
the control, 0.007 and 0.028 mg/kg/day dosage groups were 512+/-64 g, 491+/-24
g and 42Z+/-29 g, respectively (Barsotti and van Miller, 1984). .The decrease
in birth weight in the high dosage group was significantly (p<0.01) lower than
the age-matched controls. No significant differences between treatment and
control groups were detected in neonatal head circumference or crown-to-rump
measurements. Both exposure groups showed consistent weight gains, but infant
weights in the high dosage group were still lower (S64+/-97 g) at weaning
although not significantly different from the controls (896+/-90 g). It was
not reported whether the hyperpigmentation was present at birth or developed
during nursing, which may be likely due to concentration of Arocllor 1016 in
breast milk and consequent higher than maternal mg/kg/day dose. No exposure-
related hematologic effects were observed in the infants during the nursing
period (Barsotti and van Miller, 1984). One of the offspring in the high
dosage group went into shock and died on the day following weaning for unknown
reasons (Schantz et al., 1989, 1991).
Behavioral testing of the infant monkeys was first performed at age 14
months and no overt signs of PCB toxicity were observed (Schantz et al., 1989,
1991). Two-choice discrimination-reversal learning was assessed using simple
left-right spatial position', color and shape discrimination problems, with and
without irrelevant color and shape cues. One of the offspring in the low
dosage group stopped responding early in testing for an unknown reason and
could not be induced to resume; therefore, test results were obtained using 6,
7 and 6 infants in the control, low and high dosage groups, respectively. The
offspring in the high dosage (0.028 mg/kg/day) group were significantly
(p<0.05) impaired in their ability to learn the spatial position
discrimination problem (i.e., acheive 9 correct choices in 10 trials),
requiring more than 2.5 times as many'trials as their age-matched controls.
There were no significant learning differences between these groups on this
problem during overtraining (ability to achieve greater than or equal to 90%
correct choices in two consecutive daily sessions) or position reversals. The
only other exposure-related effect was significantly (p<0.05) facilitated
learning ability on the shape discrimination problem at 0.028 mg/kg/day.
Performance on delayed spatial alternation (a spatial learning and
memory task) was assessed in the offspring monkeys at age 4-6 years (Levin et
al., 1988; Schantz et al., 1991). The two Aroclor-exposed groups were not
significantly different (p<0.05) from controls in test performance. However,
the exposed groups did significantly (p<0^.05) differ from each other. The
difference between the two exposed groups was due to a combination of
facilitated performance at the low dosage (0.007 mg/kg/day) and impaired
performance at the high dosage (0.028 mg/kg/day). Although these data are
AROCHLOR.RFD -2- 02/11/92
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insufficient for establishing an exposure-effect relation due to the lack of
difference between exposed and control groups, the investigators suggested
that the performance deficit at 0.028 mg/kg/day may have been exposure-
related. The investigators noticed that a paradoxical biphasic effect
occurred on the same test when comparing low dose and high dose infants. This
same effect has been observed for lead-exposed monkeys. Impaired performance
at higher doses may be due to a more pronounced reduction of attention that
detracted from the cues critical for performing the task itself.
As summarized .above, monkeys that ingested 0.007 or 0.028 mg/kg/day
dosages of Aroclor 1016 for approximately 22 months terminating during
lactation showed no evidence of maternal toxicity. Effects occurred in the
infants of these monkeys which consisted of hairline hyperpigmentation at
greater than or equal to O.OO7 mg/kg/day, and decreased birth weight and
possible neurological impairment at 0.028 mg/kg/day. Although incompletely
described and reversible following cessation of lactation exposure, evidence
from other studies of PCBs indicates that the increased skin pigmentation was
potentially adverse. In particular, hyperpigmention is part of the spectrum
of mildly adverse dermal effects characteristic of PCBs and related compounds.
Dermal lesions including skin irritation, chloracne and increased pigmention
of skin and nails have been observed in humans occupationally exposed to
Aroclor 1016 and other Aroclor formulations by both inhalation and dermal
routes (Fischbein et al., 1979, 1982, 1985; Ouw et al., 1976;'Smith et al.,
1982). Insufficient data are available to determine possible contributions of
Aroclor 1O16 alone, direct skin exposure and contaminants in these
occupational studies. Chloracne and other dermal lesions, including dark
brown hyperpigmentation of the gingival and buccal mucosa, lips, conjunctivae
and nails, are prominant manifestions in people who consumed heated rice oil
contaminated with Kanechlor PCBs in Japan (Yusho incident) and Taiwan (Yu-
Cheng incident) (Kuratsune, 1989; Kashimoto and Miyata, 1989; Rogari, 1989).
Additionally, babies born live or stillborn to mothers who had Yusho and Yu-
Cheng exposure during pregnancy had similar hyperpigmentation and other dermal
lesions. Effects of Yusho and Yu-Cheng exposure cannot be attributed
specifically to PCBs due to relatively high concentrations of polychlorinated
dibenzofurans (PCDFs), which are generally thought to be the primary causal
agent (Kuratsune, 1989; Kashimoto and Miyata, 1989). These studies do
demonstrate, however, sensitivity of humans to 2,3,7,8-tetrachlorodibenzo-p-
dioxin (TCDD)—like toxicity, which is relevant to Aroclor 1016 assessment
because Aroclor 1O16 contains congeners structurally similar to TCDD and
dibenzofuran. Dermal effects similar to those associated with human
occupational and Yusho/Yu-Cheng PCS exposure are well documented in monkeys
following subchronic oral exposure to Aroclors 1248 or 1254 (Allen and
Norback, 1976; Allen et al., 1973, 1974; Barsotti et al., 1976; Becker et al.,
1979; Tryphonas et al., 1986a,b). Existing information therefore strongly
suggests that chronic direct exposure to Aroclor 1016 is likely to have caused
dermal effects in monkeys more severe than the reversible hyperpigmentation
resulting from transplacental/transmammary -exposure alone. Additionally, the
oral studies of Aroclors 1248 and 1254 in monkeys indicate that exposures
sufficient to cause dermal lesions are also likely to cause nondermal effects
such as developmental and hepatic toxicity. Based on the learning deficits
described above and the reduced birth weiq^rs cf prenatally-exposed monkeys,
the-O.028 mg/kg/day dosage is a LOAEL in
AROCH_OR.RFD -3- , O2/11/9C
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Decreased birth weight has also been reported in infants born to women
who were occupationally exposed to Arocior 1016 and other Aroclor formulations
(Taylor et al., 1984, 1989), ingested PCS-contaminated fish (Fein et al.,
19S4a,b) and ingested heated Kanechlor PCBs during the Yusho and Yu-Cheng
incidents (Rogan, 1989; Yamashita, 1977). Due to uncertain!ties regarding
actual sources of PCB exposure, contaminants and other confounding factors and
study limitations, the decreases in human birth weight cannot be attributed to
PCBs, particularly specific PCB mixtures. However, due to the consistency
with which the effect has been observed, the human data indirectly support the
Aroclor 1016-induced decreased birth weight in monkeys. The results of the
neurobehavioral tests in the monkey offspring at 14 months and 4-6 years of'
age indicate adverse learning deficits at the 0.028 mg/kg/day maternal dosage.
Evaluation of these data is complicated by possible inconsistencies in the
outcome of both the discrimination-reversal learning tests (learning was
impaired and facilitated on different problems) and the delayed spatial
alternation test (performance significantly differed between the two exposed
groups, but not between pither centred group and the- control U However, there
is evidence suggesting that deficits in di^r^Tiiriatigrf-rPVPrSZl ieaming *na
qplsVPd. £pa.t4-3l alternation are related to decreased brain dopamine (Schantz
et al., 1991), which has been observed in monkeys orally exposed to Aroclor
1016 (Seegal et al., 199O, 1991). Behavioral dysfunctions, including deficits-
in visual recognition and short-term memory, also have been observed.in
infants of human mothers who consumed fish contaminated with unknown PCB
mixtures (Fein et al., 1984a,b; Jacobsen et al., 1985, 199O; Gladen et al.,
1988). -
I.A.3 UNCERTAINTY AND MODIFYING FACTORS (ORAL RfD)
UF—100O. This represents a 10—fold factor to account for sensitive
individuals, and factors of 3-fold for each of the following: extrapolation
from animal to human, extrapolation from LOAEL to NOAEL, extrapolation from
subchronic to chronic and incomplete data base. A full lO-fold factor for
interspecies extrapolation is not considered necessary because of similarities
in toxic responses and metabolism of PCBs between monkeys and humans and the
general physiologic similarity between these species. A full 10-fold factor
for estimating a NOAEL from a LOAEL is not considered necessary because the
LOAEL was only mildly adverse as indicated by lack of maternal' toxicity. A
-------
_I.A.4 ADDITIONAL COMMENTS
Male macaque monkeys (number not reported, age 3-7 years, 5-9 kg inital
body weight) were administered Aroclor 1016 dissolved in corn oil on bread in
dosages of 0, 0.8, 1.6 or 3.2 mg/kg/day for 20 weeks (Seegal et al., 1991).
There were no overt signs of intoxication or exposure-related effects on body
weight gain. Neurochemical analyses of various regions of the brain were
performed following termination of exposure. Dose-related decreased
concentrations of dopamine were observed in the caudate nucleus, putamen,
substantia nigra and hypothalamus, but not in the globus pathidus or
hippocampus. There were no exposure-related changes in concentrations of
norepinephrine, epinephrine or serotonin. Other neurologic endpoints were not
evaluated in this study.
Subchronic oral studies of Aroclor 1016 have been performed in species
other than monkeys. As summarized below, these species were tested at dosages
higher than the 0.007 and 0.028 mg/kg/day dosages fed to monkeys in the
principal studies.
Groups of 10 female Sprague-Dawley rats (age not reported, body weight
approximately 225-250 g at start) were fed 0, 1, 5 or 50 ppm Aroelor 1016
(purity and lot number not reported) in the diet for 5 months (Byrne et al.,
1988). The Aroclor was dissolved in acetone which was evaporated from the
diet prior to feeding. Using a rat food consumption factor of 0.05 kg food/kg
bw, the dosages are estimated to be 0.05, 0.25 and 2.5 mg/kg/day. Serum levels
of adrenal cortex hormones were evaluated 4 times throughout the treatment
period. Adrenal dehydroepiandrosterone (DHEA) and dehydroepiandrosterone
sulfate (DHS) levels were significantly (p<0.05) reduced at 0.05 mg/kg/day and
higher doses after approximately 100 days of exposure. Serum corticosterone
(the principal glucocorticoid in rats), adrenal weight, adrenal histology and
nonadrenal endpoints other than food consumption were not evaluated. Food
consumption did not significantly differ between and among control and
treatment groups. Because insufficient information is available to determine
whether the decreases in circulating adrenal hormones were physiologically
significant, it is uncertain whether the dosages are NOAELs or LOAELs for
Aroclor 1016 in rats.
Male Balb/c mice (age not reported, 18-20 g body weight at start) were
fed Aroclor 1016 (purity and lot number not reported) mixed in diet at
concentrations of 0 or 5 ppm for 3 or 6 weeks (Loose et al., 1978). Using a
mouse food consumption factor of 0.13 kg food/kg bw, the dosage is estimated
to be 0.65 mg/kg/day. Sensitivity to Salmonella typhosa endotoxin (15 mice
per endotoxin dose) and resistance to infection by Plasmodium berghei (malaria
parasitemia; number of mice not reported) were evaluated. Sensitivity to the
endotoxin was significantly (p<0.05) increased after 3 weeks of exposure as
indicated by endotoxin LD50 values of 152 and 844 ug in the Aroclor-exposed
and control groups, respectively. Sensitivity to the endotoxin after 6 weeks
of Aroclor exposure was not evaluated. There were no significant (p<0.05)
effects of Aroclor exposure for 3 or 6 weeks on malaria lethality as indicated
by postinoculation survival time. No other endpoints were evaluated in this
study. Splenic cells from C57B1/6 male mice (18-20 g body weight at start,
number and age not reported) exposed to 167 ppm (2.1.7.1 mg/kg/day) dietary
Aroclor 1016 for 3 weeks elicited a greater graft-versus-host reaction than
AROCHLOR.RFD -5- 02/11/92
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controls when injected into neonates (Silkworth and Loose, 1978). Based on
the decreased resistance to infection leading to death, 0.65 mg Aroclor
1016/kg/day is a LOAEL for imnunotoxicity for subchronic exposure in male
mice.
Aulerich and Ringer (1977) performed a breeding study in which groups of
8 female and 2 male adult pastel mink (body weight not reported) were fed
diets containing 0 or 2 ppm Aroclor 1016 (purity and lot number not reported)
for 39 weeks or until the kits were 4 weeks of age. The Aroclor was dissolved
1n acetone which was evaporated from the diet prior to feeding. Using assumed
values of 150 g/day for food consumption and 0.8 kg for body weight for female
mink (Bleavins et a!., 1980), the estimated dosage of Aroclor 1016 is 0.4 ,
mg/kg/day. Monthly determinations showed no statistically significant
(p<0.05) differences between the control and treated mink in body weight gain,
.hemoglobin, and hematocrit. Additionally, tabulated data showed no treatment-
related effects on female survival, numbers of females mated, number of
females that gave birth, number of kits born alive or dead, number of births
per female, average birth weight or number of kits alive at 4 weeks.
Additional salient information regarding the design or results of this study
were not reported. The evidence for lack of treatment-related effects on body
weight, hematology, reproduction and survival suggests that 0.4 mg/kg/day is a
NOEL for Aroclor 1016 in mink.
Groups of adult Pastel mink (body weight not reported) were fed diet
containing 0 ppm (24 females and 6 males) or 20 ppm (12 females and 3 males)
Aroclor 1016 (purity and lot number not reported) during a 247-day breeding
study (Bleavins et a!., 1980). The Aroclor was dissolved in acetone which was
evaporated from the diet prior to feeding. Using assumed values of 150 g/day
for food consumption and 0.8 kg for body weight for female mink reported by
the investigators, the estimated dosage of Aroclor 1016 is 3.8 mg/kg/day.
There were no deaths in the exposed or control males. Mortality was higher in
the exposed females [25% (3/12) compared to 12.5% (3/24) in controls], but no
clear difference in survival time was observed. Necropsies for gross
abnormalities were performed on all control and treated mink that died; these
showed effects only in the treated mink consisting of emaciation characterized
by an almost complete absence of body fat. Histologic examinations were not
performed. The incidence of mated females giving birth was reduced in the
exposed group [44.4% (4/9) compared to 76.2% (16/21) in controls], but average
gestation length, live births and birth weight did not significantly differ
(p>0.05) between exposed and control groups. Body weight at age 4 weeks,
average number of infants per lactating female and infant biomass (average
body weight gain through age four weeks x average number of infants raised per
lactating female) were significantly (p<0.05) reduced in the exposed group.
Mortality during the first 4 weeks of life was increased in the exposed group
[56.0% (14/25) compared to 24.1% (19/79) in controls]. The investigators
noted that the adverse effects on reproduction do not appear to be due to an
effect on spermatogenesis since PCB-treated male mink have had acceptable
levels of reproduction when mated to untreated females in other studies. The
evidence for impaired reproduction and increased maternal and postnatal
mortality suggests that 3.8 mg Aroclor 1016/kg/day is an PEL in mink.
Although the PEL from this study and NOEL of 0.4 mg/kg/day from Aulerich and
Ringer (1977) suggest that the dose-severity slope for Aroclor 1016 in mink is
steep, neither study tested sufficient numbers of animals or dosage levels to
draw definitive conclusions.
AROCHLOR.RFD -6- 02/11/92
-------
Human data directly useful for risk assessment of Aroclor 1016 are not
available. Studies of the general population who presumably were exposed to
PCBs by consumption of contaminated food, particularly neurobehavioral
evaluations of infants exposed in utero and/or through lactation, have been
reported, but the original PCS mixtures, exposure levels and other details of
exposure are not known (Kreiss et al., 1981; Humphrey, 1983; Fein et al.,
1984a,b; Jacobson et al., 1984a, 1985, 1990a,b; Rogan et al.,_ 1986; Gladen et
al., 1988). Most of the information on health effects of PCB mixtures in
humans is available from studies of occupational exposure. Some of these
studies examined workers who had some occupational exposure to Aroclor 1016,
but sequential or concurrent exposure to other Aroclor mixtures nearly always
occurred, exposure involved dermal as well as inhalation routes (relative
contribution by each route not known), and monitoring data are lacking or
inadequate (Fischbein et al., 1979, 1982, 1985; Fischbein, 1985; Warshaw et
al., 1979; Smith et al., 1982; Lawton et al., 1985).
Information specifically on the oral absorption of Aroclor 1016 is not
available, but studies of individual congeners and PCB mixtures of higher
chlorine content in animals indicate, in general, that PCBs are readily and
extensively absorbed. These studies have found oral absorption efficiency on
the order of 75 to >90% in rats, mice,.monkeys and ferrets (Albro and
Fishbein, 1972; Allen et al., 1974; Tanabe et al., 1981; Bleavins et al.,
1984; Clevenger et al., 1989); A study of a 54% chlorine PCB mixture provides
direct evidence of absorption of PCBs in humans after oral exposure (Buhler et
al., 1988), and indirect evidence of oral absorption of PCBs by humans is
available from studies of ingestion of contaminated fish by the general
population (Schwartz et al., 1983; Kuwabara et al., 1979). There are no
quantitative data regarding inhalation absorption of PCBs in humans but
studies of workers exposed suggest that PCBs are well absorbed by the
inhalation and dermal routes (Maroni et al., 1981a,b; Smith et al., 1982;
Wolff, 1985). PCBs distribute preferentially to adipose tissue and
concentrate in human breast milk due to its high fat content (Jacobson et al.,
1984b; Ando et al., 1985).
The metabolism of PCBs following oral and parenteral administration in
animals has been extensively studied and reviewed, but studies in animals
following inhalation or dermal exposure are lacking (Sundstronr and Hutzinger,
1976; Safe, 1980; Sipes and Schnellmann, 1987). Information on metabolism of
PCBs in humans is limited to occupationally exposed individuals whose intake
is derived mainly from inhalation and dermal exposure (Jensen and Sundstrom,
1974; Wolff et al., 1982; Schnellmann et al., 1983; Safe et al., 1985; Fait et
al., 1989). In general, metabolism of PCBs depends on the number and position
of the chlorine atoms on the phenyl- ring of the constituent congeners (i.e.,
congener profile of the PCB mixture) and animal species. Although only
limited data are available on metabolism of PCBs following inhalation
exposure, there is no reason to suspect that PCBs are metabolized differently
by this route.
Data exist on the in vitro hepatic metabolism and in vivo metabolic
clearance of 2,2',3,3',6,6'-hexachlorobiphenyl and 4,4'-dichlorobipheny1
congeners in humans, monkeys, dogs and rats (Schnellmann et al., 1985). Both
of these congeners are present in Aroclor 1016, but the hexachlorbiphenyl is
only a minor constituent. For each congener, the Vmax values for metabolism
in the monkey, dog and rat are consistent with the respective metabolic
AROCHLOR.RFD -7- 02/11/92
-------
clearance values found in vivo. Thus, the kinetic constants for PCB
metabolism obtained from the dog, monkey and rat hepatic microsomal
preparations were good predictors of in vivo metabolism and clearance for
these congeners. In investigations directed at determining which species most
accurately predicts the metabolism and dispostion of PCBs in humans, the in
vitro metabolism of these congeners was also studied using human liver
microsomes (Schnellmann et a!., 1983, 1984). Available data suggest that
metabolism of PCBs in humans would most closely resemble that of the monkey
and rat. For example, the in vitro apparent Km and Vmax are comparable
between humans and monkeys. These studies show consistency between the in
vitro and in vivo findings and collectively indicate that metabolism of the
two congeners is similar in monkeys and humans.
__I.A.5. CONFIDENCE IN THE ORAL RfD
Study: Medium
Data Base: Medium
RfD: Medium
The critical study (i.e., series of studies on the same animals) rates a
medium confidence. This was well conducted in a sensitive animal species that
closely resembles man in many respects, and evaluated sensitive endpoints of
PCB toxicity in maternal animals and offspring. The data base rates medium
confidence based on limited toxicity and reproductive data in different
species. Although specific data on Aroclor 1016 are not extensive, the
critical effect is consistent with those of other PCBs and the available human
toxicity data are consitent with the animal findings. Medium confidence in the
RfD follows.
_I.A.6. EPA DOCUMENTATION AND REVIEW OF THE ORAL RfD
U.S. EPA. 1980. Ambient Water Quality Criteria Document for Polychlorinated
Biphenyls. Prepared by the Office of Health and Environmental Assessment,
Environmental Criteria and Assessment Office, Cincinnati, OH for the Office of
Water Regulations and Standards, Washington, DC. EPA-440/5-80/068. NTIS
PB81-117798/AS.
U.S. EPA. 1984. Health Effects Assessment for Polychlorinated Biphenyls.
Prepared by the Office of Health and Environmental Assessment, Environmental
Criteria and Assessment Office, Cincinnati, OH for the Office of Emergency and
Remedial Response, Washington, DC. EPA-540/1-86/004. • NTIS 86-134152/AS.
U.S. EPA. 1989. Ambient Water Quality Criteria Document Addendum for
Polychlorinated Biphenyls. Prepared by the Office of Health and Environmental
Assessment, Environmental Criteria and Assessment Office, Cincinnati; OH.
AROCHLOR.RFD -8- 02/11/92
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U.S. EPA. 1990. Drinking Water Criteria Document for Polychlorinated
Biphenyls (PCBs). Prepared by the Office of Health and Environmental
Assessment, Environmental Criteria and Assessment Office, Cincinnati, OH for
the Office of Drinking Water, Washington,,DC. Final. ECAQ-CIN-414 (December,
1990).
Agency RfD Work Group Review:
Verification Date: , . .
I.A.7. EPA CONTACTS (ORAL RfD).
John L. Cicmanec / ORD -— (513)569-7481 / FTS 684-7481
-./'—(") - / FTS
_VI. REFERENCES
Albro, P.W. and L. Fishbein. 1972. Intestinal absorption of polychlorinated
biphenyls in rats. Bull. Environ. Contam. Toxicol. 8: 26—31.
Allen, J.R. and D.H. Morback. 1976. Pathobiological responses of primates to
polychlorinated biphenyl exposure. In: Proceedings of the National Conference
on Polychlorinated Biphenyls. EPA 56O/6-75-OO4. p. 43-49.
Allen, J.R., L.J. Abrahamson and D.H. Norback. 1973. Biological effects of
polychlorinated biphenyls and triphenyls on the. subhuman primate. Environ.
Res. 6: 344-354.
Allen, J.R., D.H. Norback and I.C. Hsu. 1974. Tissue modifications in
monkeys as related to absorption, distribution, and excretion of
polychlorinated biphenyls. Arch. Environ.. Contam. Toxicol. 2: 86-95.
Ando, M., H. Saito and I. Wakisaka. 1985. Transfer of polychlorinated
biphenyls (PCBs) to newborn infants through the placenta and mothers' milk.
Arch. Environ. Contam. Toxicol. 14: 51-57.
Aulerich, R.J. and R.K. Ringer. 1977. Current status of PCB toxicity to
mink, and effect on their reproduction. Arch. Environ. Contam. Toxicol. 6:
279-292.
Barsotti, D.A., R.J. Marlar and J.R. Allen. 1976. Reproductive dysfunction
in rhesus monkeys exposed to low levels of polychlorinated biphenyls (Aroclor
1248). Food Cosmet. Toxicol. 14: 99-1O3.
Barsotti, D.A., and J.P. Van Miller. 1984. Accumulation of a commercial
polychlorinated biphenyl mixture (Arochlor 1016) in adult rhesus monkeys and
their nursing infants. Toxicology 30:31-44.
AROCHLOR.RFD -9- . 02/11/92
-------
Seeker, G.M., W.P. McNulty and M. Bell. 1979. Polychlorinated biphenyls-
i^duced morphologic changes in the gas.ric mucosa of the rhesus monkey.
Invest. 4O: 373.
Bleavins, M.R., R.J. Aulerich and R.K. Ringer. 198O. Polychlorinated
biphenyls (Aroclors 1O16 and 1242): Effects on survival and reproduction in
mink and ferrets. Arch. Environ. Contam. Toxicol. 9: 627-635i
Bleavins, M.R., W.J. Breslin, R.J. Aulerich,et al. 1984. Placental and
mammary transfer of a polychlorinated ciphenyl mixture (Aroclor 1254) in the
European ferret (Mustela putorius furo;. Environ. Toxicol. Chem. 3: 637-644.
Buhler F., P. Schmid and C.H. Schlatter. 1988. Kinetics of PCB elimination
in man. Chemosphere. 17: 1717-1726.
Byrne, J.J., J.P. Carbone and M.G. Peoe. 1988. Suppression of serum adrenal
cortex hormones by chronic low-dose pclychlorobiphenyl or polybromobiphenyl
treatments. Arch. Environ. Contam. lexical. 17: 47-53.
Clevenger, M.A., S.M. Roberts, D.L. La-tin et al. 1989. The pharmacokinetics-
of 2,2',5,5'-tetrachlorobiphenyl and 3,3',4,4'-tetrachlorobiphenyl and its
relationship to toxicity. Toxicol. Apol. Pharmacol. 10O: 315-327.
Fait, A., E. Grossman, S. Self et al. 1989. Polychlorinated biphenyl
congeners in adipose tissue lipid and serum of past and present transformer
repair workers and a comparison group. Fund. Appl. Toxicol. 12: 42-55.
Fein, G.S., J.L. Jacobson, S.W. Jacobson et al.. 1984a. Intrauterine exposure
of humans to PCBs: Newborn effects. U.S. Environmental Protection Agency,
Duluth, MN. EPA 60O/53-84-O6O. NTIS =384-188-887.
Fein, G.B., J.L. Jacobson, S.W. Jacobson et al. 1984b. Prenatal exposure to
polychlorinated biphenyls: Effects on Girth size and gestation age. J...
Pediatr. 105: 315-32O.
Fischbein, A. 1985. Liver function tests in workers with occupational
exposure to polychlorinated biphenyls (PCBs): Comparison with Yusho and Yu-
Cheng. Environ. Health Perspect. 6O: 145-15O.
Fischbein, A., M.S. Wolff, R. Lilis et al. 1979. Clinical findings among
PCB-exposed capacitor manufacturing workers. Ann. NY'Acad. Sci. 32O:
703-715.
Fischbein, A., M.S. Wolff, J. Bernstein et al. 1982. Dermatological findings
in capacitor manufacturing workers exposed to dielectric fluids containing
polychlorinated biphenyls (PCBs). ArcD- Environ. Health. 37: 69-74.
Fischbein, A., J.N. Rizzc, 5.J. Solomor et Al. ^785- Oculodermatological
findings in workers with occupational- eApo<5^re to pclychlorinated biphenyls
(PCBs). 3r. J. Ind. Med. 42: 426-43O.
AROCHJDR.RFD -1C- 02/11/92
-------
G laden, B.C., 1-..J. Rogan, P. Hardy et al. 1988. Development after exposure
to polychlorinated biphenyls and dichlorodiphenyl dichloroethene
transplacentallv and t~-ough human milk. J. Pediatr. 113: 991-995.
Humphrey, H.E.E. 1983. Population studies of PCBs in Michigan residents.
In: PCBs: Human and Environmental Hazards, P.M. D'ltri, M. Kamrin, Ed.
Butterworth, Boston, MA., p. 299-31O.
Jacobson, J.L., S.W. Jacobson, P.M. Schwartz et al. I984a. Prenatal exposure
to an environmental toxin: A test of .the multiple effects model. Dev.
Psychobiol. 20: 523-532.
Jacobson, J.L., 3.G. Fein, S.W, Jacobson et al. 1984b. The transfer of
polychlorinated biphenyls (PCBs) and polybrominated biphenyls (PBBs) across
the human placenta and into maternal milk. J. Public Health. 74: 378-379.
Jacobson, S.W., 3.G. Fein, J.L. Jacobson et al. 1985. The effect of
intrauterine PC3 exposure on visual recognition memory. Child Dev. 56:
856-860.
Jacobson, J.L., S.W. Jacobson and H.E.B. Humphrey. 199Oa. Effects of in
utero exposure to polychlorinated-biphenyls and related contaminants on
cognitive-functioning in young children. J. Pediatr. 116: 38-45.
Jacobson, J.L., S.W. Jacobson and H.E.B. Humphrey. l99Ob. Effects of ,
exposure to PCBs and related compounds on growth and activity in children.
Neurotoxicol. Teratol. 12: 319-326.
Jensen, S. and G. Sundstrom. 1974. Structures and levels of most
chlorobiphenyls in two technical PCS products and in human adipose tissue.
Ambio. 3: 70-76.
Kashimoto, T. and H. Miyata. 1986. Differences between Yusho and other kinds
of poisoning involving only PCBs. Chapter 1. In: PCBs and the Environment,
J.S. Waid, Ed., Vol.. 3. CRC Press, Boca Raton, p. 2-26.
Kreiss, 1C., M.M. Zack, R.D. Kimbrough et al. 1981. Association of blood
pressure and polychlorinated bipnenyl levels. J. Am. Med. Assoc. 245:
2505-5O9.
Kuratsune, M. 1989. Yusho, with reference to Yu-Cheng. Chapter 13. .In:
Halogenated Biphenyls, Terphenyls, Naphthalenes, Dibenzodioxins and related
Products, 2nd ed.,.R.D. Kimbrough and A.A. Jensen, Ed. Elsevier Science
Publishers, Amsterdam, p. 381-4OO.
Kuwabara, K., T. Yakushiji, I. Watanabe et al. 1979. Increase in the human
blood PCB levels promptly following ingestion of fish containing PCBs. Bull.
Environ. Contarn. Toxicol. 21: 273-278.
*>*»
Lawton, R.W., M.R. Ross, J. Feingold et al. 1985. Effects of PCB exposure on
biochemical and hematological findings in capacitor vsorkers. Environ. Health
Perspect. 6O: 165-184.
AROCHLOR.RFD -11- O2/11/92
-------
Levin, E. D., S. L. Schantz, and R. E. Bowman. 1988. Delayed spatial
alternation deficits resulting from perinata PCS exposure in monkeys. Arch
Toxicol 62:267-273.
Loose, L.D., J.B. Silkworth, K.A. Pittman et al. 1978. Impaired host
resistance to endotoxin and malaria in polychlorinated biphenyl- and
hexachlorobenzene—treated mice. Infect. Immun. 20: 3O-35.
Maroni, M., A. Columbi, B.'Arbosti et al. 198la. Occupational exposure to
polychlorinated biphenyls in electrical workers. II. Health effects. Br. J.
Ind. Med. 38: 55-6O.
Maroni, M., A. Columbi, G. Arbosti et al. 1981b. Occupational exposure to
polychlorinated biphenyls in electrical workers. I. Environmental and blood
polychlorinated biphenyls concentrations. Br. J. Ind. Med. 38: 49-54.
Ouw, H.K., G.R. Simpson and D.S. Silyali. 1976. Use and health effects of
Aroclor 1242, a polychlorinated biphenyl in an electrical industry. Arch.
Environ. Health. 31: 189-194.
Rogan, W.J. 1989. Yu-Cheng, Chapter 14. In: Halogenated Biphenyls,
Terphenyls, Naphthalenes, Dibenzodioxins and Related Products, 2nd ed., R.D.
Kimbrough and A.A. Jensen', Ed. Elsevier Science Publishers, Amsterdam, p.
4O1-15. , .
Rogan, W.J., B.C. Gladen, J.D. McKinney et al. 1986. Neonatal e?ffects of
transplacental exposure to PCBs and DDE. J. Pediatr. 109: =335-341.
Safe, S. 198O. Metabolism, uptake, storage and bioaccumulation of
halogenated aromatic pollutants.. In: Halogenated Biphenyls, Terphenyls,
Naphthalenes, Dibenzodioxins and Related Products, R.D.Kimbrough, Ed.
Elsevier Science Publishers, Amsterdam, p. 81-1O7.
Safe, S., S. Bandiera, T. Sawyer et al. 1985. PCBs: Structure-function
relationships and mechanism of action. Environ. Health Perspect,. 60: 47-56.
Schantz, S.L., E.D. Levin, R. E. Bowman et al. 1989. Effects of perinata PCS
exposure on discrimination-reversal learning in monkeys. Neurotox. Teratol.
11:243-250.
Schantz, S.L., E.D. Levin and R.E. Bowman. 1991. Long-term neurobehavioral
effects of perinatal polychlorinated biphenyl (PCB) exposure in monkeys.
Environ. Toxicol. Chem. 10(6): 747-756. -
Schnellmann, R.B., C.W. Putnam and I.G. Sipes. 1983. Metabolism of
2,2',3,3',6,6'-hexachlorobiphenyl and 2,2',4,4" ,5,5'-hexachlorobiphenyl by
human hepatic microsomes. Biochem. Pharmacol. 32: 3233-3239.
f- ,
Schnellmann, R.G., R.F. Volp, C.W. Putnam and I.G. Sipes. 1984. The
hydroxylation, dechlorination and glucuroniCation of 4,4'-dichlorobiphenyl by
human hepatic microsomes. Biochem. Pharmacc::. 33: 3503-3509.
AROCHLOR.RFD -12- . 02/11/5'"
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Schneilmann, R.G., E.M. Vickers and I.G. Sipes. 1985. Metabolism and
disDosition of polychlorinated biphenyis. In: Reviews in Biochemical
Toxicology, Vol. 7, E.Hodgson, J.R.' Bend and R.M. Philpot, Ed. Elsevier
Press, Amsterdam, p. 247-282.
Schwartz, P.M., S.W. Jacobson, 6. Fein et al. 1983. Lake Michigan fish
consumption as a source of polychlorinated biphenyis in human cord serum,
maternal serum, and milk. Am. J. Public Health. 73: 293-296.
Seegal, R.F., B. Bush and W. Shain. 199O. Lightly chlorinated 0-substitutsa
PC3 congeners decrease dopamine in nonhuman primate brain and in tissue
culture. Toxicol. Appl. Pharmacol. 1O6(1): 136-144.
Seegal, R.F., B. Bush and K.O. Brosch. 1991. Comparison of effects of
Aroclor 1016 and Aroclor 126O on non-human primate catecholamine function.
Toxicol. 66(2): 145-164.
Silkworth, J.B. and L.D. Loose. 1978. Cell mediated immunity in mice fed
either Aroclor 1016 or hexachlorobenzene. Toxicol. Appl. Pharmacol. 45: 326.
(Abstract)
Sipes, I.J. and R.G. Schneilmann. 1987. Biotransformation of PCBs metabolic
pathways and mechanisms. In: Polychlorinated Biphenyis (PCBs): Mammalian and
Environmental Toxicology, S. Safe, Ed. Environmental Toxic Series, Vol. 1. ,
Springer Verlag New York, Inc., Secaucus, NJ.
Smith, A.B., J. Schloemer, L.K. Lowry et al. 1982. Metabolic and health
consequences of occupational exposure to polychlorinated biphenyis. Br. J.
Ind. Med. 39: 361-369.
Sundstrom, G. and O. Hutzinger. 1976. The metabolism of chlorobiphenyls.
Chemosphere. 5: 267-298.
Tanabe, S., Y. Nakagawa and R. Tatsukawa. 1981. Absorption efficiency and
biological half-life of individual chlorobiphenyls in rats treated with
Kanechlor products. Agric. Biol. Chem. 45: 717-726.
Taylor, P.R., C.E. Lawrence, H.L. Hwang et al. 1984. Polychlorinated
biphenyis: Influence on birthweight and gestation. Am. J. Public Health. 74:
1153-1154.
Taylor, P.R., J.M. Stelma and C.E. Lawrence. 1989. The relation of
polychlorinated biphenyis to birth weight and gestational age in the offspring
of occupationally exposed mothers. Am. J. Epidemiol. 129: 395-4O6.
Tryphonas, L., S. Charbonneau, H.. Tryphonaa et al. 1986a. Comparative
aspects of Aroclor 1254 toxicity in adult cynomolgus and rhesus monkeys: A
pilot study. Arch. Environ. Contam. Toxicol. 15: 159-169.
Trypnonas, L., D.L. Arnold, Z. Zawldzka et al. I986b. A pilot study in adult
rhesus monkeys (M. mulatta) treated with Aroclor 1254 for two years. Toxicoi.
• Pathol. 14: 1-1O. . .
AROCHLOR.RFD -'-- O2/11/<5I
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Warshaw, R., A. Fischbein, J. Thornton et al. 1979. Decrease in vital
capacity in PCE-exposed workers in a capacitor manufacturing facility. Ann.
NY Acad. Sci. 320: 277-283.
Wolff, M.S. 1995. Occupational exposure to polychlorinated biphenyls (PCBs)
EJnviron. Health Perspect. 6O: 133-138.
Wolff, M.S., J. Thornton, A. Fischbein et al. 1982. Disposition of
polychlorinated biphenyl congeners in occupationally exposed persons.
Toxicol. Appl. Pharmacol. 62: 294-3O6.
Yamashita, F. 1977. Clinical features of polychlorobiphenyls (PCB)-induced
fetopathy. Paediatrician. 6: 2O-27.
AROCH-OR.RFD -14- , O2/11/*.
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEA.RCH AND DEVELOPMENT
ENVIRONMENTAL. CRITERIA AND ASSESSMENT Or RCE
CINCINNATI. OHIO A526B
SUBJECT:
TO:
FROM:
RfD/RfC Work Group Meeting—June 23, 24, and 25, 1992
RfD/RfC Work Grcn
Daniel Guth I
(Acting Co-Chair^
Annie M. Jarabek)
Office of Health and Environmental Assessment
Research Triangle Park, NC
Michael. L. Dourson _
Office of Health and Environmental Assessment
Cincinnati, OH
Kenneth A. Poirier
(Acting Co-Chair for M. Dourson},
Office of Health and Environmen
Cincinnati, OH
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Chemical Name: Arochlor 1016 (RfD) Date: 06/23/92
CAS#: 12674-11-2
Office: OHEA/STA
Previous Decision: Under Review
Previous Discussion Dates: 02/21/90, 03/25/92
Outstanding Issues: The Work Group requested OHEA/STA to ask
HERL to review learning deficit data from critical studies.
1. Documentation: Adequate. , . .
2. Rationale:
A series of developmental toxicity studies in the same group
of monkeys (Barsotti and van Miller 1984; Levin et al. 1988;
Schantz et al. 1989, 1991) were chosen as co-critical
studies. In these studies, the monkeys were exposed to a
commercial mixture of Arochlor 1016 (containing no
chlorinated d'ibenzofurans) prenatally and throughout
lactation until weaning at 4 months. Behavioral testing
began at 14 months of age (two choice discrimination-
reversal test) and again at 4-6 years of age (delayed
spatial alternation test). Reduced birth weight that
occurred at a LOAEL of 18.4 mg/kg for 21.8 months (0.030
mg/kg/day) (NOAEL = -4.6 .mg/kg for 21.8 months [0.008
mg/kg/day]) was identified as the critical effect.. OHEA/STA
conducted additional" statistical analyses with raw data
obtained from the investigators. Based on the results of
these analyses, gestation length, sex, and sire ID were •
ruled out as causes of the significant decrease in birth
weight observed in the high-dose animals. At the Work
Group's request, HERL/NTD evaluated the neurobehavioral
data; and concluded that because the dosed groups did not
differ significantly from control (even though they differed
significantly from each other), neurotoxicity should not be
considered a critical effect. Hyperpigmentation was
observed-in the offspring of animals exposed to both 0.008
mg/kg/day and 0.030 mg/kg/day, but this effect was not
considered adverse. OPPT questioned the appropriateness of
the dose calculation; the doses were calculated for the
entire dosing period (including the lactation period) but
the critical effect occurred during gestation and at birth.
OPPT suggested that the doses be calculated based on food
intake and body weight during pregnancy only. OHEA/STA
responded that these data were not available, but agreed to
add some text that more accurate doses could not be
calculated. The Work Group concurred with the choice of
critical study and effect.
11
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3. Study:
OHEA/STA stated that R. MacPhail (HERL/NTD) evaluated the
Schantz et al. (1989, 1991) and Levin et al. (1988) studies.
Dr. MacPhail concluded that since the neurological effects
observed in the arochlor 1016 exposed monkeys did not differ
from the controls, neurotoxicity should not be highlighted
as an effect.
OHEA/STA obtained exact birth,weight data from the
investigators. Gestational length, sex and sire were
factored out in the statistical analysis of the data
(Attachment #5). A significant reduction in birth weight
was observed in the high dose group. The Work Group agreed
with the selection of the principal studies, critical•effect
and N.OAEL/LOAEL designation.
4. Uncertainty Factor:
OHEA/RDT suggested that an additional uncertainty factor of
3 be included for the lack of male reproductive toxicity
data and a multigeneration reproduction study. Region VIII
commented that an uncertainty factor of 3 for use of a
subchronic study was not needed because the principal study
is a developmental toxicity study. OHEA/HHAG responded that
there was a potential for longer term effects due to storage
in adipose tissue. OPPT suggested decreasing the
interspecies variability uncertainty factor to 3 because a
sensitive species is being used. OHEA/CMA commented that
they were uncomfortable with an overall uncertainty factor
of 100, with medium confidence in the study, data base and
RfD. After extended discussion, the Work Group agreed with
an overall uncertainty factor of 100; 3H, 3A, 3S, and 3DB.
The Work Group asked that the discussions of the uncertainty
factors for intra- and inter-species extrapolation, and lack
of lifetime data and data base deficiencies be combined.
5. Modifying Factor: None
6. Calculation:
OPPT commented that the doses for the principal studies
should not be calculated for the duration of the entire
dosing period but rather up until parturition. OHEA/STA
responded that the data were not available to calculate
doses until parturition. The Work Group requested that
OHEA/STA include a statement to this effect.
12
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7. Confidence Statement:
OHEA/RDT requested that the data base gap (lack of male
reproduction and multigeneration reproduction studies) be
called out. The Work Group agreed with medium confidence in
the study, data base and RfD.
8. Are the old issues resolved: -Yes.
9. Outstanding issues: None,
10. Additional work:
1) OHEA/STA was asked to revise the statement on page 2
that arochlor 1016 in breast milk was higher than the
maternal mg/kg/day dose.
2) OST was asked to include a discussion of risk
characterization for arochlors. OST agreed.
3) The Work Group requested that Dr. MacPhail's comments on
the neurological effects be included in the IRIS file.
4) OHEA/STA was asked to rewrite the uncertainty factor
text to call out 4 partial areas of uncertainty.
11. New Status: The RfD of 8 E-5 mg/kg/day for arochlor 1016 is
ON IRIS: NOT ON IRIS:
No change to IRIS (IR) X Verified (V)
Pending change to IRIS (RE) Under Review (UR)
Withdraw and new RfD Not Verifiable (NV)
Verified (WV)
Withdraw and Still
Under Review (WR)
New Verification Date: 06/23/92
13
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
ENVIRONMENTAL CRITERIA AND ASSESSMENT OFFICE
CINCINNATI. OHIO 45268
SUBJECT: RfD/RfC Work Group Meeting-September 22, 23 and 24, 1992
TO: RfD/RfC Work Group
FROM: Annie M. Jarabek
Office of Health and Environmental Assessment
Research Triangle Park, NC
Daniel Guth
(Acting co-chair for A. Jarabek on September 22 and 23)
Office of Health and Environmental Assessment
Research Triangle Park, NC
Michael L. Dourson
Office of Health and Environmental Assessment
Cincinnati, OH
Printed on Recycled Pace'
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GENERAL INTEREST
1. Daniel Guth (ECAO/HPA) served as acting co-chair for Annie Jarabek on September 22
and 23.
2. OHEA/STA requested that methyl mercury RfD be withdrawn from the agenda.
3. OHEA/HPA requested that the d-limonene RfD be withdrawn from the agenda.
4. Due to time constraints, the RfC for dichlorvos was not discussed at the meeting.
GENERAL DISCUSSION
Arochlor 1016 RfD - John Cicmanec COHEA/STAI
At the September 22 meeting, John Cicmanec discussed correspondence on Arochlor
1016 from General Electric. General Electric raised a number of issues regarding the
proposed RfD summary sheet (verified by the RfD/RfC Work Group) in an August 20, 1992
discussion with John Skinner and Bill Farland. These points were re-emphasized in a follow-
up letter from Stephen Ramsey to Hank Habicht (dated September 3, 1992). As noted by
John Cicmanec, these issues were discussed in detail at the previous two Work Group
meetings. The newly revised summary sheet provides clarification to the General Electric
issues by specific additions to the text pertaining to description of the principal study,
uncertainty factor, and confidence statement The Work Group was asked to submit
comments on the revised summary sheet to John.
IRIS RfD Background Document —Bob Benson (Region VIIR
At the September 24 meeting, Bob Benson presented a draft of the revised IRIS RfD
Background Document (Attachment 2) and requested comments from the Work Group.
Several members felt that the discussion on biological significance (Section 1.3.1.1) was
confusing and suggested using a different example. It was also suggested that this discussion
belongs in Section 1.3.1.2.2.
Bob requested that Work Group members provide minor and editorial comments to him in
writing. Theac-comments will be incorporated and another draft circulated.
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
ENVIRONMENTAL. CRITERIA AND ASSESSMENT OFFICE
CINCINNATI. OHIO 45268
November 16, 1992
SUBJECT: Review Notes of the Special October 15th Teleconference Meeting for the
RfD/RfC Work Group
FROM: 1~ Annie M. Jarabek OVft/.A Ovv/v^-o-v—
Co-Chair, RfD/RfC Work Group
Office of Health and Environmental Assessment
Kenneth A. Poirier, Ph.D.
Co-Chair, RfD/RfC Work
Office of Health and Environmental Assessment
TO: RfD/RfC Work Group Members
Printed on Recycled Paoer
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ALDICARB:
OPP described 'the changes in the summary sheet that were made in response to
the discussion held on September 23rd at the previous Work Group meeting. The RfD
is still based on the NOAEL described in the Rhone-Poulonc (1992) acute human study
that identified the critical effect as sweating. The rationale for choosing this effect and
the short duration of exposure is detailed in 1 .A.3. of the summary sheet on page 6. The
proposed UF of 10 was questioned. Region 1 thought that the agreed upon UF at the
previous meeting was 30, not 10. OHEA-Cin responded that a UF of 10 was an open
question pending additional explanation as provided above. Region 8 questioned why
headaches were not considered as the critical effect at the lowest dose of exposure in the
Rhone-Poulonc study. OPP reiterated the comments from the previous meeting.
Headaches are consistent with carbamate exposure, however, a joint OPPT/OW/OHEA
expert panel discounted headaches as a possible effect of treatment in this particular
exposure group because the headaches appeared toward the end of the 6 hour
observation time, rather than soon after exposure as expected from other data on
carbamates. OPP agreed to add this additional information to the summary sheet.
OHEA-HQ introduced the comments provided in a memo by Elaine Francis (OHEA)
and questioned the choice of an UF of 10 especially in light of how uncertainty factors
have historically been assigned. OHEA-RTP raised a concern on the subjectivity of the
measurements for the appearance and degree of sweating reported in the Rhone Poulonc
(1992) study. OSW and Region 8 questioned the lack of adequate documentation for
the absence of long-term human sequelae. However, it was pointed out that the
complete data base supports the endpoint of sweating as the critical effect based on the
consequences of cholinesterase inhibition. OPP also responded that it is more difficult
to justify an additional UF given what is known specifically for aldicarb and the
carbamates in general. Although several members of the Work Group expressed some
reservation for using an UFH of 10, after extended discussion-this value had the
consensus of the Work Group. OHEA commented that UF as proposed is consistent
with what has been historically used in other files. OPP stated that this reflects the data
known for human poisoning episodes.
Additional discussion was centered around the confidence statements. Given the
lack of knowledge of long-term human effects, the confidence in the data base was
deemed to be medium. Additional, study confidence in the text was suggested as being
medium to low, given the issues of subjectivity of reporting effects, duration of exposure
and small subject number in the Rhone-Poulonc (1992) study. There was no change
suggested for the confidence of the RfD.
The RfD for Aldicarb was verified at 1E-3 mg/kg-day on 10/15/92.
AROCHLOR 1016:
The primary contact, John Cicmanec, was unable to attend the special
teleconference due to previously scheduled travel. Mike Dourson filled in for John
Cicmanec. The changes to the text that were made in response to General Electric's
comments to both Hank Habicht and Erich Bretthauer were highlighted along with a
-------
more detailed memo from John Cicmanec to the Work Group regarding these points. It
was agreed that although there are some deficiencies in the Arochlor 1016 primate
studies, OHEA-HQ pointed out that they are minor in light of the fact that behavioral
testing in primates are much more reliable than any other non-human species and that
non-human primates represent the best choice for determining critical effects. OHEA-
HQ also pointed out that there were no problems with using these studies relative to
reproductive or developmental toxicity endpoints.
The Work Group was in unanimous agreement that the primate studies of
Barsotti meet the criteria of developing an RfD for Arochlor 1016. Unfortunately, due
to the length of time of the preceding discussion, insufficient time was available in the
assigned teleconference window to complete discussion of revisions to the Arochlor 1016
summary sheet. A final decision was, therefore, deferred to the November meeting.
The RfD for Arochlor 1016 is verified pending approval of the summary sheet by
the RfD/RfC Work Group.
RfD/RfC Work Group Members/Mailing List:
Larry Anderson (TS-796) Annie Jarabek (MD-52)
Monica Barren (OS-331) James Murphy (TS-796)
Robert Beliles (RD-689) Nancy Pate (MD-13)
Robert Benson (Region 8) Yogendra Patel (WH-586)
Nancy Chiu (WH-586) William Pepelko (RD-689)
John Cicmanec (ECAO-Cin) Kenneth Poirier (ECAO-Cin)
Eric Clegg (RD-689) Jon Rauscher (Region 6)
Gary Foureman (MD-52) Samuel Rotenberg (Region 3)
George Ghali (H7509C) Jennifer Seed (TS-796)
Lee Gorsky (Region 5) Mary Beth Smuts (Region 1)
Dan Guth (MD-52) Gary Welker (Region 7)
Larry Hall (MD-02) John Whalan (H7509C)
Rick Whiting (H7509C)
CC:
S. Chou (ATSDR) J. Patterson
D. Davoli (Region 10) S. Segal (ICF)
M. Dourson RfD file for Aldicarb
C. Freeman (OSHA) RfD file for Arochlor 1016
L. Ingerman (SRC-NY)
A.'Mahfouz (WH-586)
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Environmental Criteria and Assessment Office (MD-52)
Research Triangie Park, North Carolina 27711
DATE: July 6, 1993
SUBJECT: RfD/RfC Work Group Meeting Notes from November 4-5, 1992
FROM: Gary L. Foureman _
Acting Co-Chair, RfD/RfC Work Group
Office of Health and Ehvironmental Assessment
Environmental Criteria and Assessment Office/RTF (MD-52)
Kenneth A. Poirier
Co-Chair, RfD/RfC Work Group
Office of Health and Environmenal Assessment
Environmental Criteria and Assessment Office/CIN (MS-114)
-------
Chemical Name: Arochlor 1016 (RfD) Date: 11/04/92
CAS#: 12674-11-2
Office: OHEA/STA
Previous Decision: V
Previous Discussion Dates: RfD: 02/21/90, 03/25/92, 06/23/92, 09/24/92; 10/15/92;
RfC: None; CRAVE: None
Outstanding Issues: Address submitted comments in the text.
1. Documentation:
Adequate. Verified in June. Material received by ORD management following .the
June verification warranted a reexamination of the RfD summary sheet by the
primary contact. This resulted in additional clarification and documentation of the
uncertainty factor text, revision/expansion of the confidence statement with an
emphasis on the close parallel between changes seen in the Rhesus monkey and '
humans and a clarification that the principal study is a reproductive toxicity study.
OHEA/HPA questioned the significance of the Taylor et al. (1984, 1989) studies
discussed in the Principal and Supporting Studies section. OHEA/STA responded
that these studies provided positive results for developmental effects in humans
apd were most supportive of the critical effect seen in monkeys. OHEA/HPA
requested that the discussion of the Yusho and Yu-Cheng incidents be
. deemphasized and moved to the Additional Comments section because the effects
seen in these incidents were due primarily to PCDFs and not PCBs. Region VIII
requested that since the Barsotti Ph.D. dissertation was cited in the text of the
summary sheet it should be included in the references. OST requested that a
statement be added to the effect that environmental exposures to the PCBs will be
different than experimental exposure to commercial mixtures (i.e., Arochlor 1016).
OHEA/HHAG mentioned that it is also important to point out that these compounds
(i.e., the PCBs) are known to have adverse ecological effects and that the RfD is
protective only for human health.
2. Rationale:
A series of developmental toxicity studies in the same group of monkeys (Barsotti
and van Miller 1984; Levin et al. 1988; Schantz et al. 1989, 1991) were chosen as
co-principal studies. In these studies, monkeys were exposed to a commercial
mixture of Arochior 1016 (containing no chlorinated dibenzofurans) prenatally and
throughout lactation until weaning at 4 months. Behavioral testing began at 14
months of age (two choice discrimination-reversal test) and again, at 4-6 years of
age (delayed spatial alternation test). Reduced birth weight occurred at a LOAEL of
18.4 mg/kg for 21.8 months (0.03 mg/kg/day) (NOAEL = 4.6 mg/kg for 21.8
months [0.008 mg/kg/day]) and was identified as the critical effect. OHEA/STA
conducted additional statistical analyses with raw data obtained from the
investigators. Based on the results of these analyses, gestation length, sex, and
sire ID were ruled out as causes of the significant decrease in birth weight observed
in the high-dose animals. Hyperpigmentation was observed in the offspring of
-------
animals exposed to both 0.008 mg/kg/day and 0.030 mg/kg/day, but this effect
was not considered adverse. The Work Group concurred with the choice of
principal study and critical effect.
3. Study:
Region VIII requested that a more complete discussion of the feed contamination
problems in this study be incorporated and should include the fact that
contamination with other PCBs occurred in all groups and that the concentration of
the contaminants was lower than those at which a decrease in birth weight would
likely be seen. OHEA/HPA pointed out that there is a discrepancy between the
Schantz et al. papers and the Barsotti paper with regard to the birth weight of the
infants, and that this discrepancy should be pointed out. Region VIII noted that the
OHEA/STA statistical analyses included data from fathers that were treated with
Arochlor 1248 and that these data should be excluded from the analyses. The
Work Group noted that exclusion of these data should have no impact on the
results. (A statement should be added to the text that 1 -2 males in each group
received Arochlor 1248 instead of Arochlor 1016, but that further analysis showed
that this did not affect the results.
4. Uncertainty Factor:
In the revised summary sheet presented to the Work Group, OHEA/STA changed
the uncertainty factors from four factors of 3 to a factor of 10 for sensitive
individuals, a factor of 3 for interspecies extrapolation, and a factor of 3 for
database deficiencies. OHEA/RDTB noted that according to the developmental
toxicity risk assessment guidelines, an additional uncertainty factor should be
incorporated to account for less than chronic duration exposure when calculating an
RfD. This uncertainty factor is obviated only when deriving an RfDDT. Region III
questioned why an uncertainty factor of 3 was used to extrapolate from monkeys
to humans. OHEA/HHAG responded that previous work with Rhesus monkeys
(e.g., Tilson's work) provides good support that the monkey is a better predictor of
toxicity in humans than any rodent species and that a full uncertainty factor of 10
is thus not necessary. OHEA/CMA stated that four uncertainty factors of 3 each
for UF[H], UF[A], UF[S], and UF[D] is a more tenable position. The critical points
for database deficiencies include: the principal study has not been repeated, and in
general, there is a lack of multigeneraltional reproductive toxicity studies and
specifically, a lack of information on effects on reproductive function jn males that
were exposed in utero . OHEA/HPA questioned why UFH = 3. OHEA/STA
responded that the effect was seen in what is presumed to be the most sensitive
subset of the population (i.e., the fetus of non-human primate). The Work Group
agreed to a total uncertainty factor of 100 comprised of four factors of 3 each.
5. Modifying Factor: None
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6. Calculation: Not discussed.
7. Confidence Statement: ,
The confidence statement was rewritten as described in #1 above. OHEA/HHAG
questioned why the confidence in the study was not high because of the way it is
written, and suggested that the weaknesses of the database and study be more
clearly delineated to justify the medium confidence rating. OHEA/HPA requested
that there be a separate discussion of the study and database confidence because
as it is now written, the confidence statement focuses primarily on the study. The
Work Group agreed to medium confidence in the study, data base, and RfD.
8. Are the old issues resolved:
Yes. The Work Group felt that the changes incorporated into the summary sheet
adequately addressed the points submitted to ORD management.
9. Outstanding issues: None
10. Additional work:
1) The uncertainty factor text has to be rewritten to reflect four factors of 3.
; 2) The confidence statement has to be rewritten to separately discuss the
database and to more clearly point out the deficiencies in the study and the
database.
3) The discussion of the Yusho and Yu-Cheng incidents needs to be deemphasized
and moved into the Additional Comments section.
4) Discussion has to be added to the Additional Comments section regarding the
fact that environmental exposures will not be the same as commercial mixtures and
that PCBs have adverse ecological effects.
5) The feed contamination problem in the principal study has to be more fully
discussed.
6) The discrepancy in the birth weights between the Schantz et al. papers and the
Barsotti papers needs to be mentioned.
7) A statement should be added to the discussion of the principal studies that 1 -2
males in each group received Arochlor 1248 instead of Arochlor 1016, but that this
did not affect the results.
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I. A. REFERENCE DOSE FOR CHRONIC ORAL EXPOSURE (RfD)
'
Chemical — Aroclor 1016
CASRN — 12674-11-2
On-line: Pending
• ,,
THIS IS THE LATEST VERSION 1 ! (Y\le. :Vi
)
_ I.A.I. ORAL RfD SUMMARY
Critical Effect Experimental Doses*
UF
MF
^^sr^oisriiT^
* f ^ ..rt^x.w ^ •*• •* ff * *%
RfD
~^^^j^
iegtt''?-ff.*g-n>-,:U:-,r#V!:K&i.
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^Conversion Factors: Dos age corresponds to a reported total average intake of
4.52 mg/kg bw during an average exposure period of 21.8 months (Schantz et
al., 1989, 1991). Arochlor 1016 was administered as 0.25 ppm in the diet.
_ I .A. 2. PRINCIPAL "AND SUPPORTING STUDIES (ORAL RfD)
Barsotti, D.A. and J.P. van Miller. 1984. Accumulation of a commercial
polychlorinated biphenyl mixture (Arochlor 1016) in adult rhesus monkeys and
their nursing infants. Toxicology. 30: 31-44.
Levin, E.D., S.L. Schantz and R.E Bowman. 1988. Delayed spatial alternation
deficits resulting from perinatal PCB exposure in monkeys. Arch. Toxicol.
62: 267-273.
Schantz, S.L., E.D. Levin, R.E. Bowman et al. 1989. Effects of perinatal PCB
exposure on discrimination-reversal learning in monkeys. Neurotoxicol.
Teratol. 11: 243-250.
Schantz, S.L., E.D. Levin and R.E. Bowman. 1991. Long-term neurobehavioral
effects of perinatal polychlorinated biphenyl (PCB) exposure in monkeys.
Environ. Toxicol. Chem. 10: 747-756.
These are a series of reports that evaluated perinatal toxicity and
long-term neurobehavioral effects of Arochlor 1016 in the same groups of
infant monkeys. Arochlor 1016 was administered to groups of 8 adult female
rhesus monkeys (body weight not reported) via diet in concentrations of 0,
0.25 or 1.0 ppm for 21.8+/-2.2 months. The Arochlor 1016 is a commercial
mixture devoid of chlorinated dibenzofurans (Barsotti and van Miller, 1984).
Exposure began 7 months prior to breeding (6 control females and 7 exposed
NAME
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females per dose were bred to unexposed males) and continued until offspring
were weaned at age 4 months. Based on a reported total Arochlor intake of
4.52+/-0.56 and 18.41+/-3.64 mg/kg over the 21.8-month exposure period
(Schantz et al., 1989, 1991), the low and high doses are estimated to be 0.008
and 0.03 mg/kg/day, respectively. No exposure-related effects on maternal food
intake, general appearance, hematology, serum chemistry (SGPT, lipid and
cholesterol analyses) or number of breedings were observed (Barsotti and van
Miller, 1984). All monkeys had uncomplicated pregnancies, carried their
infants to term and delivered viable offspring. Teratologic examinations were
not performed. Mean birth weights of the infants in the control, 0.008 and
0.03 mg/kg/day dose groups were 512+/-64 g, 491+/-24 g and 422-f/-29 g,
.respectively (Barsotti and van Miller, 1984). The decrease in birth weight in
the high dose group was significantly (p<0.01) lower than controls. Further
statistical analysis of the infant birth weight data indicated that gestation
length did not significantly affect birth weight and the distribution of male
and female infants in the various dose groups could not account for the
difference in birth weights among the dose groups. No significant differences
between treatment and control groups were detected in neonatal head
circumference of crown-to-rump measurements. Both exposure groups showed
consistent weight gains, but infant weights in the high dose group were still
lower (S64+/-97 g) at weaning although not significantly different from the
controls (896+/-90 g). Hyperpigmentation was present at birth in the low and
high dose infants but did not persist once dosing was stopped. This clinical
change was determined not to be a critical adverse effect. The concentration
of Arochl.or 1016 in breast milk was higher than the maternal mg/kg/day dose.
No exposure-related hematologic effects were observed in the infants during
the nursing period (Barsotti and van Miller, 1984). One of the offspring in
the high dose group went into shock and died on the day following weaning for
unknown reasons (Schantz et al., 1989, 1991).
Behavioral testing of the infant monkeys was first performed at age 14
months and no overt signs of PCS toxicity were observed (Schantz et al.,. 1989,
1991). Two-choice discrimination-reversal learning was assessed using simple
left-right spatial position, color and shape discrimination problems, with and
without irrelevant color and shape cues. One of the offspring in the low
dosage group stopped responding early in testing for an unknown reason and
could not be induced to resume; therefore, test results were obtained using 6,
7 and 6 infants in the control, low and high dosage groups, respectively. The
offspring in the high dosage (0.03 mg/kg/day) group were significantly
(p<0.05) impaired in their ability to learn the spatial position
discrimination problem (i.e., achieved 9 correct choices in 10 trials),
requiring more than 2.5 times as many trials as their age-matched controls.
There were no significant learning differences between these groups on this
problem during overtraining (ability to achieve greater than or equal to 90%
correct choices in two consecutive daily sessions) or position reversals. The
only other exposure-related effect was significantly facilitated learning
ability (p<0.05) on the shape discrimination problem at 0.03 mg/kg/day.
Performance on delayed spatial alternation (a spatial learning and
memory task) was assessed in the offspring monkeys at age 4-6 years (Levin et
al., 1988; Schantz et al., 1991). The two Arochlor-exposed groups were not ~
significantly different from controls (p<0.05) in test performance. However,
the exposed groups did significantly (p<0.05) differ from each other. The
NAME -2- 00/00/91
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difference between the two exposed groups was due to a combination of
facilitated performance at the low dose (0.008 mg/kg/day) and impaired
performance at the high dose (0.03 mg/kg/day). Although these data are
insufficient for establishing an exposure-effect relation due to the lack of
difference between exposed and control groups, the investigators suggested
that the performance deficit at 0.03 mg/kg/day may have been exposure-related.
The investigators noticed that a paradoxical biphasic effect occurred on the
same test when comparing low-dose and high-dose infants. This same effect has
been observed for lead-exposed monkeys. Impaired performance at higher doses
may be .due to a more pronounced reduction of attention that detracted from the
cues critical for performing the task itself.
As summarized above, adult monkeys that ingested 0.008 or 0.03 mg/kg/day
dosages of Arochlor 1016 for approximately 22 months, terminating during
lactation, showed no evidence of maternal toxicity. Effects occurred in the
infants of these monkeys consisting of hairline hyperpigmentation at greater
than or equal to 0.008 mg/kg/day, and decreased birth weight and possible
neurological impairment at 0.03 mg/kg/day. Dermal lesions including skin
irritation, chloracne and increased pigmentation of skin and nails have been
observed in humans occupationally exposed to Arochlor 1016 and other Arochlor
formulations by both inhalation and dermal routes (Fischbein et a!., 1979,
1982, 1985; Ouw et a!., 1976; Smith et al., 1982). Insufficient data are
available to determine possible contributions of Arochlor 1016 alone, direct
skin exposure and contaminants in these occupational studies. Chloracne and
other dermal lesions, including dark brown hyperpigmentation of the gingival
and buccal mucosa, lips, conjunctivae and nails, are prominent manifestations
in people who consumed heated rice oil contaminated with Kanechlor PCBs in
Japan (Yusho incident) and Taiwan (Yu-Cheng incident) (Kuratsune, 1989;
Kashimoto and Miyata, 1986; Rogan, 1989). Additionally, babies born live or
stillborn to mothers who had Yusho and Yu-Cheng exposure during pregnancy had
similar hyperpigmentation and other dermal lesions. Effects of Yusho and Yu-
Cheng exposure cannot be attributed specifically to PCBs duetto relatively
high concentrations of polychlorinated dibenzofurans (PCDFs)', which are
generally thought to be the primary causal agent (Kuratsune, 1989; Kashimoto
and Miyata, 1989). These studies demonstrate human toxicity similar to that
seen with the nonhuman primate studies.' Sensitivity of humans to 2,3,7,8-
tetrachlorodibenzo-p-dioxin (TCDD) is relevant to Arochlor 1016 assessment
because Arochlor 1016 contains congeners structurally similar to TCDD and
dibenzofuran. Dermal effects similar to those associated with human
occupational and Yusho/Yu-Cheng.PCB exposure are well documented in monkeys
following subchronic oral exposure to Aroclors 1248 or 1254 (Allen and
Norback, 1976; Allen et al., 1973, 1974; Barsotti et al., 1976; Becker et al.,
1979; Tryphonas et al., 1986a,b). Based on the reduced birth weights of
prenatally-exposed monkeys, the 0.03 mg/kg/day dose is a LOAEL in monkeys.
Decreased birth weight has also been reported in infants born to women <•
who were occupationally exposed to Arochlor 1016 and other Arochlor
formulations (Taylor et al., 1984, 1989), ingested PCB-contaminated fish (Fein
et al., 1984a,b) and ingested heated Kanechlor PCBs during the Yusho and Yu-
Cheng incidents (Rogan, 1989; Yamashita, 1977). Due to uncertainties
regarding actual sources of PCB exposure, and other confounding factors and
study limitations, the decreases in human birth weight cannot be solely
attributed to PCBs, particularly specific PCB mixtures. However, due to the
consistency with which the effect has been observed, the human data is
NAME -3- 00/00/91
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consistent with the Arochlor 1016-induced decreased birth weight in monkeys.
The results of the neurobehavioral tests in the monkey offspring at 14 months
and 4-6 years of age indicate adverse learning deficits at the 0.03 mg/kg/day
maternal dose. Evaluation of these data is complicated by possible
inconsistencies in the outcome of both the discrimination-reversal learning
tests (learning was impaired and facilitated on different problems) and the
delayed spatial alternation test (performance significantly differed between
the two exposed groups, but not between either control group and the control).
However,, there is evidence suggesting that deficits in discrimination-reversal
learning and delayed spatial alternation are related to decreased brain
dopamine (Schantz et al., 1991), which has been observed in monkeys orally
exposed to Arochlor 1016 (Seegal et al., 1990, 1991). Behavioral dysfunctions,
including deficits in visual recognition and short-term memory, also have been
observed in infants of human mothers who consumed fish contaminated with
unknown PCB mixtures (Fein et al., 1984a,b; Jacobsen et al., 1985, 1990;
Gladen et al., 1988).
_ I.A.3. UNCERTAINTY AND MODIFYING FACTORS (ORAL RfD)
ai gnk'Bys^anax^iumansr,and cthe genera^ j
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MF - 1.
_I.A.4. ADDITIONAL STUDIES / COMMENTS (ORAL RfD)
Male macaque monkeys (Macaca nemistrina age 3-7 years, 5-9 kg initial body
weight) were administered Arochlor 1016 dissolved in corn oil on bread in
doses of 0, 0.8, 1.6 or 3.2 mg/kg/day for 20 weeks (Seegal et al., 1991).
There were no overt signs of intoxication or exposure-related effects on body
weight gain. Neurochemical analyses of various regions of the brain were
performed following termination of exposure. Dose-related decreased
concentrations of dopamine. were observed in the caudate nucleus, put amen,
substantia nigra and hypothalamus, but not in the globus pallidus or
hippocampus. There were no exposure-re! ated changes in concentrations of
norepinephrine, epinephrine or serotonin. Other neurologic endpoints were not
evaluated.
Subchronic oral studies of Arochlor 1016 have been performed in species
other than monkeys. As summarized below, these species were tested at doses
higher than the 0.008 and 0.03 mg/kg/day doses fed to monkeys in the principal
studies.
NAME
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Groups of 10 female Sprague-Dawley rats (age not reported, body weight
approximately 225-250 g at start) were fed 0, 1, 5 or 50 ppm Arochlor 1016
(purity and lot number not reported) in the diet for 5 months (Byrne et al.,
1988). The Arochlor was dissolved in acetone that was evaporated from the
diet prior to feeding. Using a rat food consumption factor of 0.05 kg food/kg
bw, the doses are estimated to be 0.05, 0.25 and 2.5 mg/kg/day. Serum
levels of adrenal cortical hormones were evaluated 4 times throughout the
treatment period. Adrenal dehydroepiandrosterone (DHEA) and
dehydroepiandrosterone sulfate (DHS) levels were significantly (p<0.05)
reduced at 0.05 mg/kg/day and higher doses after approximately 100 days of
exposure. Serum corticosterone (the principal glucocorticoid in rats),
adrenal weight, adrenal histology and nonadrenal endpoints other than food
consumption were not evaluated. Food consumption did not significantly differ
between and among control and treatment groups. Because insufficient
information is available to determine whether the decreases in circulating
adrenal hormones were physiologically significant, it is uncertain whether the
doses are NOAELs or LOAELs for Arochlor 1016 in rats.
Hale Balb/c mice (age not reported, 18-20 g body weight at start) were
fed Arochlor 1016 mixed in diet at concentrations of 0 or 5 ppm for 3 or 6
weeks (Loose et al., 1978). Using a mouse food consumption factor of 0.13 kg
food/kg bw, the dosage is estimated to be 0.65 mg/kg/day. Sensitivity to
Salmonella typhosa endotoxin (15 mice per endotoxin dose) and resistance to
infection by Plasmodium berghei (malaria parasitemia; number of mice not
reported) were evaluated. Sensitivity to the endotoxin was significantly
(p<0.05) increased after 3 weeks of exposure as indicated by endotoxin LD50
values of 152 and 844 ug in the Arochlor-exposed and control groups,
respectively. Sensitivity to the endotoxin after 6 weeks of Arochlor exposure
was not evaluated. There were no significant (p<0.05) effects of Arochlor
.exposure for 3 or 6 weeks on malaria lethality as indicated by post
inoculation survival time. No other endpoints were evaluated in this study.
When injected into neonates, splenic cells from C57B1/6 male mice exposed to
167 ppm (21.71 mg/kg/day) dietary Arochlor 1016 for 3 weeks elicited a greater
graft-versus-host reaction than controls (Silkworth and Loose, 1978). Based
on the decreased resistance to infection leading to death, 0.65 mg Arochlor
1016/kg/day is a LOAEL for iramunotoxicity for subchronic exposure in male
mice.
Aulerich and Ringer (1977) performed a breeding study in which groups of
8 female and 2 male adult pastel mink were fed diets containing 0 or 2 ppm
Arochlor 1016 for 39 weeks or until the kits were 4 weeks of age. The
Arochlor was dissolved in acetone which was evaporated from the diet prior to
feeding. Using assumed values of 150 g/day for food consumption and 0.8 kg
for body weight for female mink (Bleavins et al., 1980), the estimated dosage
of Arochlor 1016 is 0.4 mg/kg/day. Monthly determinations showed no
statistically significant differences (p<0.05) between the control and treated
mink in body weight gain, hemoglobin, and hematocrit. Additionally, tabulated
data showed no treatment-related effects on female survival, numbers of
females mated, number of females that gave birth, number of kits born alive or
dead, number of births per female, average birth weight or number of kits
alive at 4 weeks. The evidence for lack of treatment-related effects on body
weight, hematology, reproduction and survival suggests that 0.4 mg/kg/day is a
NOEL for Arochlor 1016 in mink.
NAME -5- 00/00/91
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Groups of adult Pastel mink (body weight not reported) were fed a diet
containing 0 ppm (24 females and 6 males) or 20 ppm (12 females and 3 males)
Arochlor 1016 during a 247-day breeding study (Bleavins et a!., 1980). The
Arochlor was dissolved in acetone which was evaporated from the diet prior to
feeding. Using assumed values of 150 g/day for food consumption and 0.8 kg
for body weight for female mink reported by the investigators, the estimated
dosage of Arochlor 1016 is 3.8 mg/kg/day. There were no deaths in the exposed
or control males. Mortality was higher in the exposed females [2556 (3/12)
compared to 12.5% (3/24) in controls], but no clear difference in survival
time was observed. Necropsies for gross abnormalities were performed on all
control and treated mink that died; these showed effects only in the treated
mink consisting of emaciation characterized by an almost complete absence of
body fat. Histologic examinations were not performed. The incidence of mated
females giving birth was reduced in the exposed group [44.4% (4/9) compared to
76.2% (16/21) in controls], but average gestation length, live births and
birth weight did not significantly differ (p>0.05) between exposed and control
groups. Body weight at age 4 weeks, average number of infants per lactating
female and infant biomass (average body weight gain through age four weeks x
average number of infants raised per lactating female) were significantly
(p<0.05) reduced in the exposed group. Mortality during the first 4 weeks of
life was increased in the exposed group [56.0% (14/25) compared to 24.1%
(19/79) in controls]. The investigators noted that the adverse effects on
reproduction do not appear to be due to an effect on spermatogenesis since
PCB-treated male mink have had acceptable levels of reproduction when mated to
untreated females in other studies. The evidence for impaired reproduction
and increased maternal and postnatal mortality suggests that 3.8 mg Arochlor
1016/kg/day is an PEL in mink. Although the FEL from this study and NOEL of
0.4 mg/kg/day from Aulerich and Ringer (1977) suggest that the dose-severity
slope for Arochlor 1016 in mink is steep, neither study tested sufficient
numbers of animals or dosage levels to allow definitive conclusions to be
drawn.
The human data available useful for risk assessment of Arochlor 1016
are useful only in a qualitative manner. Studies of the general population
who were exposed to PCBs by consumption of contaminated food, particularly
neurobehavioral evaluations of infants exposed in utero and/or through
lactation, have been reported, but the original PCB mixtures, exposure levels
and other details of exposure are not known (Kreiss et a!., 1981; Humphrey,
1983; Fein et a!., 1984a,b; Jacobson et al., 1984a, 1985, 1990a,b; Rogan et
a!., 1986; Gladen et al., 1988). Most of the information on health effects of
PCB mixtures in humans is available from studies of occupational exposure.
Some of these studies examined workers who had some occupational exposure to
Arochlor 1016, but in these studies concurrent exposure to other Arochlor
mixtures nearly always occurred, exposure involved dermal as well as
inhalation routes (relative contribution by each route was not known), and
monitoring data were lacking or inadequate (Fischbein et al., 1979, 1982,
1985; Fischbein, 1985; Warshaw et al., 1979; Smith et al., 1982; Lawton et
al., 1985).
Information specifically on the oral absorption of Arochlor 1016 is not
available, but studies of individual congeners and PCB mixtures of higher
chlorine content in animals indicate, in general, that PCBs are readily and
extensively absorbed^ These studies have found oral absorption efficiency on
the order of 75 to >90% in rats, mice, monkeys and ferrets (Albro and
NAME -6- 00/00/91
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Fishfaein, 1972; Allen et al., 1974; Tanafae et al., 1981; Bleayins et al.,
1984; Clevenger et al., 1989). A study of a PCB mixture containing 54 %
chlorine provides direct evidence of absorption of PCBs in humans after oral
exposure (Buhler et al., 1988), and indirect evidence of oral absorption of
PCBs by humans is available from studies of ingestion of contaminated fish by
the general population (Schwartz et al., 1983; Kuwabara et al., 1979). There
are no quantitative data regarding inhalation absorption of PCBs in humans but
studies of exposed workers suggest that PCBs are well absorbed by the
inhalation and dermal routes (Maroni et al., 1981a,b; Smith et al., 1982;
Wolff, 1985). PCBs distribute preferentially to adipose tissue and
concentrate in human breast milk due to its high fat content (Jacobson et al.,
1984b; Ando et al., 1985).
The metabolism of PCBs following oral and parenteral administration in
animals has been extensively studied and reviewed, but studies in animals
following inhalation or dermal exposure are lacking (Sundstrom and Hutzinger,
1976; Safe, 1980; Sipes and Schnellmann, 1987). Information on metabolism of
PCBs in humans is limited to occupationally exposed individuals whose intake
is derived mainly from inhalation and dermal exposure (Jensen and Sundstrom,
1974; Wolff et al., 1982; Schnellmann et al., 1983; Safe et al., 1985; Fait et
al., 1989). In general, metabolism of PCBs depends on the number and position
of the chlorine atoms on the phenyl rings of the constituent congeners (i.e.,
congener profile of the PCB mixture) and animal species. Although only
limited data are available on metabolism of PCBs following inhalation
exposure, there is no reason to suspect that PCBs are metabolized differently
by this route.
Data exist on the in vitro hepatic metabolism and in vivo metabolic
clearance of 2,2',3,3',6,6'-hexachlordbiphenyl and 4,4'-dichlorobiphenyl
congeners in humans, monkeys, dogs and rats (Schnellmann et al., 1985). Both
of these congeners are present in Arochlor 1016, but the hexachlorobiphenyl is
only a minor constituent. For each congener, the Vmax values for metabolism
in the monkey, dog and rat are consistent with the respective metabolic
clearance values found in vivo. Thus, the kinetic constants for PCB
metabolism obtained from the dog, monkey and rat hepatic microsomal
preparations were good predictors of in vivo metabolism and clearance for
these congeners. In investigations directed at determining which species most
accurately predicts the metabolism and disposition of PCBs in humans, the in
vitro metabolism of these congeners was also studied using human liver
raicrosomes (Schnellmann et al., 1983, 1984). Available data suggest that
metabolism of PCBs in humans most closely resemble that of the monkey and rat.
For example, the in vitro apparent Km and Vmax for humans and monkeys are
comparable. These studies show consistency between the in vitro and in vivo
findings and collectively indicate that metabolism of the two congeners is
similar in monkeys and humans.
I .A. 5. CONFIDENCE IN THE ORAL RfD
NAME -7- 00/00/91
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•&'AJ» -.2 _£A:»_ _*_.<'?'.- j k. '' ^i _ f J*»^1|»«|»<.V»» I »W .^»<,»,j^l«l/i»**t'; *^^»Hl"-*-'!;\»»^-%»»*«l»»«-»>»V/^w^»%^fT"*'*JJ«« ^!U<.>-trgJg
stootlesxJers^pel^djrm^Ai^an^aci^
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wheii. compared ^o^th
___I.A.6. EPA DOCUMENTATION AND REVIEW OF THE ORAL RfD
EPA source document - U.S. EPA. 1980. Ambient Water Quality Criteria
Document for Polychlorinated Biphenyls. Prepared by the Office of Health and
Environmental Assessment, Environmental Criteria and Assessment Office,
Cincinnati, OH for the Office of Water Regulations and Standards, Washington,
DC. EPA-440/5-80/068. NTIS PB81-117798/AS.
Other EPA Documentation - U.S. EPA. 1984. Health Effects Assessment for
Polychlorinated Biphenyls. Prepared by the Office of Health and Environmental
Assessment, Environmental Criteria and Assessment Office, Cincinnati, OH for
the Office of Emergency and R- I.A.5.
U.S. EPA. ,1989. Ambient Water Quality Criteria Document Addendum for
Polychlorinated Biphenyls. Prepared by the Office of Health and Environmental
Assessment, Environmental Criteria and Assessment Office, Cincinnati, OH.
U.S. EPA. 1990. Drinking Water Criteria Document for Polychlorinated
Biphenyls (PCBs). Prepared by the Office of Health and Environmental
Assessment, Environmental Criteria and Assessment Office, Cincinnati, OH for
the Office of Drinking Water, Washington, DC. Final. ECAO-CIN-414 (December,
1990). •
NAME
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Agency Work Group Review: ../../..
Verification Date: 6/24/92
I.A.7. EPA CONTACTS (ORAL RfD)
John L. Cicraanec / ORD — (513)569-7481 / FTS (513) 569-7481
Michael L. Dourson / Ord (513)569-7531 / FTS (513) 569-7531
JI. REFERENCES
Albro, P.W. and L. Fishbein. 1972. Intestinal absorption of polychlbrinated
biphenyls in rats. Bull. Environ. Contam. Toxicol. 8: 26-31.
Allen, J.R. and D.H. Norback. 1976. Pathobiological responses of primates to
polychlorinated biphenyl exposure. In: Proceedings of the National Conference
on Polychlorinated Biphenyls. EPA 560/6-75-004. p. 43-49.
Allen, J.R., L.J. Abrahamson and D.H. Norback. 1973. Biological effects of
polychlorinated biphenyls and triphenyls on the subhuman primate. .Environ.
Res. 6: 344-354.
Allen, J.R., D.H. Norback and I.C. .Hsu. 1974. Tissue modifications in
monkeys as related to absorption, distribution, and excretion of
polychlorinated biphenyls. Arch. Environ. Contam. Toxicol4 2: 86-95.
Ando, M., H. Saito and I. Wakisaka. 1985. Transfer of polychlorinated
biphenyls (PCBs) to newborn infants through the placenta and mothers1 milk.
Arch. Environ. Contain. Toxicol. 14: 51-57.
Aulerich, R.J. and R.K. Ringer. 1977. Current status of PCB toxicity to
mink, and effect on their reproduction. Arch. Environ. Contam. Toxicol. 6:
279-292.
Barsotti, D.A., R.J. Marlar and J.R. Allen. 1976. Reproductive dysfunction
in rhesus monkeys exposed to Tow levels of polychlorinated biphenyls (Aroclor
1248). Food Cosmet. Toxicol. 14: 99-103.
Barsotti, D.A., and J.P. Van Miller. 1984. Accumulation of a commercial
polychlorinated biphenyl mixture (Arochlor 1016} in adult rhesus monkeys and
their nursing infants. Toxicology 30:31-44.
Becker, G.M., W.P. McNulty and M. Bell. 1979. Polychlorinated biphenyls-
induced morphologic changes in the gastric mucosa of the rhesus monkey.
Invest.' 40: 373.
Bleavins, M.R., R.J. Aulerich and R.K. Ringer. 1980. Polychloriinated
biphenyls (Arochlors 1016 and 1242): Effects on survival and reproduction in
mink and ferrets. Arch. Environ. Contam. Toxicol. 9: 627-635.
NAME -9- 00/00/91
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Bleavins, M.R., W.J. Breslin, R.J. Aulerich et al. 1984. Placenta! and
mammary transfer of a polychlorinated biphenyl mixture (Aroclor 1254) in the
European ferret (Mustela putorius furo). Environ. Toxicol. Chem. 3: 637-644.
Buhler F., P. Schmid and C.H. Schlatter. 1988. Kinetics of PCB elimination
in man. Chemosphere. 17: 1717-1726.
Byrne, J.J., J.P. Carbone and M.G. Pepe. 1988. Suppression of serum adrenal
cortex hormones by chronic low-dose polychlorobiphenyl or polybromobiphenyl
treatments. Arch; Environ. Contam. Toxicol. 17: 47-53.
Clevenger, H.A., S.M. Roberts, D.L. Lattin et al. 1989. The pharmacokinetics
of 2,2',5,5'-tetrachlorobiphenyl and 3,3',4»4'-tetrachlorobiphenyl and its
relationship to toxicity. Toxicol. Appl. Pharmacol. 100: 315-327.
Fait, A., E. Grossman, S. Self et al. 1989. Polychlorinated biphenyl
congeners in adipose tissue lipid and serum of past and present transformer
repair workers and a comparison group. Fund. Appl. Toxicol. 12: 42-55.
Fein, G.G., J.L. Jacobson, S.W. Jacobson et al. 1984a. Intrauterine exposure
of humans to PCBs: Newborn effects. U.S. Environmental Protection Agency,
Duluth, MN. EPA 600/53-84-060. NTIS PB84-188-887.
Fein, G.G., J.L. Jacobson, S.W. Jacobson et al. 1984.b. Prenatal exposure to
polychlorinated biphenyls: Effects on birth size and gestation age. J.
Pediatr. 105: 315-320.
Fischbein, A. 1985. Liver function tests in workers with occupational
exposure to polychlorinated biphenyls (PCBs): Comparison with Yusho and Yu-
Cheng. Environ. Health Perspect. 60: 145-150.
Fischbein, A., M.S. Wolff, R. Lilis et al. 1979. Clinical findings among
PCB-exposed capacitor manufacturing workers. Ann. NY Acad. Sci. 320:
703-715.
Fischbein, A., M.S. Wolff, J. Bernstein et al. 1982. Dennatological findings
in capacitor manufacturing workers exposed to dielectric fluids containing
polychlorinated biphenyls (PCBs). Arch. Environ. Health. 37: 69-74.
Fischbein, A., J.N. Rizzo, S.J. Solomon et al. 1985. Oculodermatological
findings in workers with occupational exposure to polychlorinated biphenyls
(PCBs). Br. J. Ind. Med. 42: 426-430.
Gladen, B.C., W.J. Ro'gan, P. Hardy et al. 1988. Development after exposure
to polychlorinated biphenyls and dichlorodiphenyl dichloroethene
transplacentally and through human milk. J. Pediatr. 113: 991-995.
Humphrey, H.E.B. 1983. Population studies of PCBs in Michigan residents.
In: PCBs: Human and Environmental Hazards, F.M. D'ltri, M. Kararin, Ed..
Butter-worth, Boston, MA. p. 299-310.
Jacobson, J.L.,'S.H. Jacobson, P.M. Schwartz et al. 1984a. Prenatal exposure
to an environmental toxin: A test of the multiple effects model. Dev.
Psychobiol. 20: 523-532.
NAME -10- 00/00/91
-------
Jacobson, J.L., G.G. Fein, S.W. Jacobson et al. 1984b. The transfer of
polychlorinated biphenyls (PCBs) and polybrominated biphenyls (PBBs) across
the human placenta and into maternal milk. J. Public Health. 74: 378-379.
Jacobson, S.W., G.G. Fein, J.L. Jacobson et al. 1985. The effect of
intrauterine PCB exposure on visual recognition memory. Child Dev. 56:
856-860.
Jacobson, J.L., S.W. Jacobson and H.E.B. Humphrey. 1990a. Effects of in
utero exposure to polychlorinated-biphenyls and related contaminants on
cognitive-functioning in young children. J. Pediatr. 116: 38-45.
Jacobson, J.L., S.W. Jacobson and H.E.B. Humphrey. 1990b. Effects of
exposure to PCBs and related compounds on growth and activity in children.
Neurotoxicol. Teratol. 12: 319-326.
Jensen, S. and G. Sundstrom. 1974. Structures and levels of most
chlorobiphenyls in two technical PCB products and in human adipose tissue.
Ambio, 3: 70-76.
Kashimoto, T. and H. Miyata. 1986. Differences between Yusho and other kinds
of poisoning involving only PCBs. Chapter 1. In: PCBs and the Environment,
J.S. Waid, Ed., Vol. 3. CRC Press, Boca Raton, p. 2-26.
Kreiss, K., H.M. Zack, R.D. Kimbrough et al. 1981. Association of blood
pressure and polychlorinated biphenyl levels. J. Am. Med. Assoc. 245:
2505-509.
Kuratsune, H. 1989. Yusho, with reference to-Yu-Cheng. Chapter 13. In:
Halogenated Biphenyls, Terphenyls, Naphthalenes, Oibenzodioxins and related
Products, 2nd ed., R.D. Kimbrough and A.A. Jensen, Ed. Elsevier Science
Publishers, Amsterdam, p. 381-400.
Kuwabara, K., T. Yakushiji, I. Watanabe et al. 1979. Increase in the human
blood PCB levels promptly following ingestion of fish containing PCBs. Bull.
Environ. Contam. Toxicol. 21: 273-278.
Lawton, R.W., M.R. Ross, J. Feingold et al. 1985. Effects of PCB exposure on
biochemical and hematological findings in capacitor workers. Environ. Health
Perspect. 60: 165-184. •
Levin, E. D., S. L. Schantz, and R. E. Bowman. 1988. Delayed spatial
alternation deficits resulting from perinatal PCB exposure in monkeys. Arch
Toxicol 62:267-273.
Loose, L.D., J.B. Silkworth, K.A. Pittman et al. 1978. Impaired host
resistance to endotoxin and malaria in polychlorinated biphenyl- and
hexachlorobenzene-treated mice. Infect. Immun. 20: 30-35.
Haroni, M., A. Columbi, G. Arbosti et al. 1981a. Occupational exposure to
polychlorinated biphenyls in electrical workers. II. Health effects. Br. J.
Ind. Med. 38: 55-60.
NAME -11- 00/00/91
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Maroni, M., A. Columbi, G. Arbosti et al. 1981b. Occupational exposure to
polychlorinated biphenyls in electrical workers. I. Environmental and blood
polychlorinated biphenyls concentrations. Br. J. Ind. Med. 38: 49-54.
Ouw, H.K., G.R. Simpson and D.S. Silyali. 1976. Use and health effects of
Aroclor 1242, a polychlorinated biphenyl in an electrical industry. Arch.
Environ. Health. 31: 189-194.
Rogan, W.J. 1989. Yu-Cheng, Chapter 14. In: Halogenated Biphenyls, =
Terphenyls, Naphthalenes, Dibenzodioxins and Related Products, 2nd ed., R.D.
Kimbrough and A.A. Jensen, Ed. Elsevier Science Publishers, Amsterdam, p.
401-15.
Rogan, W.J., B.C. Gladen, J.D. McKinney et al. 1986. Neonatal effects of
transplacental exposure to PCBs and DDE. J. Pediatr. 109: 335-341.
Safe, S. 1980. Metabolism, uptake, storage and bioaccumulation of
halogenated aromatic pollutants. In: Halogenated Biphenyls, Terphenyls,
Naphthalenes, Dibenzodioxins and Related Products, R.D.Kimbrough, Ed.
Elsevier Science Publishers, Amsterdam, p. 81-107.
Safe, S., S. Bandiera, T. Sawyer et al. 1985. PCBs: Structure-function
relationships and mechanism of action. Environ. Health Perspect. 60: 47-56.
Schantz, S.L., E.D. Levin, R. E. Bowman et al. 1989. Effects of perinata PCB
exposure on discrimination-reversal learning in monkeys. Neurotox. Teratol.
11:243-250.
Schantz, S.L., E.D. Levin and R.E. Bowman. 1991. Long-term neurobehavioral
effects of perinatal polychlorinated biphenyl (PCB) exposure in monkeys.
.EnViron. Toxicol. Chem. 10(6): 747-756.
Schnellmann, R.G., C.U. Putnam and I.G. Sipes. 1983. Metabolism of
2,2',3,3',6,6'-hexachlorobiphenyl and 2,2',4,4',5,5'-hexachlorobiphenyl by
human hepatic microsomes. Biochem. Pharmacol. 32: 3233-3239.
Schnellmann, R.G., R.F. Volp, C.W. Putnam and I.G. Sipes. 1984. The
hydroxylation, dechlorination and glucuronidation of 4,4'-dichlorobiphenyl by
human hepatic microsomes. Biochem. Pharmacol. :33: 3503-3509.
Schnellmann, R.G., E.M. Vickers and I.G. Sipes. 1985. Metabolism and
disposition of polychlorinated biphenyls. In: Reviews in Biochemical
Toxicology, Vol. 7, E.Hodgson, J.R. Bend and R.M. Philpot, Ed. Elsevier
Press, Amsterdam, p. 247-282.
Schwartz, P.M., S.W. Jacobson, G. Fein et al. 1983. Lake Michigan fish
consumption as a source of polychlorinated biphenyls in human cord serum,
maternal serum, and milk. Am. J. Public Health. 73: 293-296.
Seegal, R.F., B. Bush and W. Shain. 1990. Lightly chlorinated 0-substituted
PCB congeners decrease dopamine in nonhuman primate brain and in tissue
culture. Toxicol. Appl. Pharmacol. 106(1): 136-144.
NAME -12- 00/00/91
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Seagal, R.F., B. Bush and K.O. Brosch. 1991. Comparison of effects of
Aroclor 1016 and Aroclor 1260 on non-human primate catecholamine function.
Toxicol. 66(2): 145-164.
Silkworth, J.B. and L.D. Loose. 1978. Cell mediated immunity in mice fed
either Aroclor 1016 or hexachlorobenzene. Toxicol. Appl. Pharmacol. 45: 326.
(Abstract)
Sipes, I.J. and R.G. Schnellmann. 1987.. Biotransformation of PCBs metabolic
pathways and mechanisms. In: Polychlorinated Biphenyls (PCBs): Mammalian and
Environmental Toxicology, S. Safe, Ed. Environmental Toxic Series, Vol. 1.
Springer Verlag New York, Inc., Secaucus, NJ.
Smith, A.B., J. Schloemer, L.K. Lowry et al. 1982. Metabolic and health
consequences of occupational exposure to polychlorinated biphenyls. Br. J.
Ind. Med. 39: 361-369.
Sundstrom, G. and 0. Hutzinger. 1976. The metabolism of chlorobiphenyls.
Chemosphere. 5: 267-298.
Tanabe, S., Y. Nakagawa and R. Tatsukawa. 1981. Absorption efficiency and
biological half-life of individual chlorobiphenyls in rats treated with
Kanechlor products. Agric. Biol. Chem. 45: 717-726.
Taylor, P.R., C.E. Lawrence, H.L. Hwang et al. 1984. Polychlorinated
biphenyls: Influence on birthweight and gestation. Am. J. Public Health. 74:
1153-1154.
Taylor, P.R., J.M. Stelma and C.E. Lawrence. 1989. The relation of
polychlorinated biphenyls to birth weight and gestational age in the offspring
of occupationally exp.osed mothers. Am. J. Epidemic!. 129: 395-406.
Tryphonas, L., S. Charbonneau, H. Tryphonas et al. 1986a. Comparative
aspects of Aroclor 1254 toxicity in adult cynomolgus and rhesus monkeys: A
pilot study. Arch. Environ. Contam. Toxicol. 15: 159-169.
Tryphonas, L., D.L. Arnold, 1. Zawldzka et al. 1986b. A pilot study in adult
rhesus monkeys (M. mulatta) treated with Aroclor 1254 for two years. Toxicol.
Pathol. 14: 1-10.
Warshaw, R., A. Fischbein, J. Thornton et al. 1979. Decrease in vital
capacity in PCB-exposed workers in a capacitor manufacturing facility. Ann.
NY Acad. Sci. 320: 277-283.
Wolff, M.S. 1985. Occupational exposure to polychlorinated biphenyls (PCBs).
Environ. Health Perspect. 60: 133-138.
Wolff, M.S., J. Thornton, A. Fischbein et al. 1982. Disposition of
polychlorinated biphenyl congeners in occupationally exposed persons.
Toxicol. Appl. Pharmacol. 62: 294-306.'
Yamashita, F. 1977. Clinical features of polychlorobiphenyls (PCB)-induced
fetopathy. Pediatrician. 6: 20-27.
NAME -13- 00/00/91
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SUBJECT: RfD/RfC Work Group Meeting—February 9-11,1993
TO: RfD/RfC Work Group
FROM: Annie M. Jarabek
Office of Health and Environmental Assessment
Research Triangle Park, NC
Kenneth A. Poirier
Office of Health and Environmental Assessment
Cincinnati, OH
NAME
L Anderson
R. Beliles
R. Benson
S. Chou
J. Cicmanec
E. Clegg
G. Foureman
J. Gift
L Gorsky
M. Greenberg
0. Guth
LHall
J. Hinz
A. Jarabek
J. Murphy
N. Pate
Y. Patel
W. Pepelko
K. Poirier
S. Segal
J. Whalan
R. Whiting
IN ATTENDANCE WERE:
OFFICE
February 9,1993
OPPT
OHEA/HHAG
Region Vill
ATSDR
OHEA/STA
OHEA/RDTB
OHEA/HPA
OHEA/HPA
Region V
OHEA/HPA
OHEA/HPA
ORD/HERL
OHEA/HPA
OHEA/HPA
OPPT/HERD
OAQPS
OW/OST
OHEA/HHAG
OHEA/CMA
Clement/OHEA-RTP
OPP/HED
OPP/HED
PHONE
(202) 260-1564
(202) 260-3018
(303) 293-1694
(404)639-6308
(513) 569-7481
(202)260-8914
(919)541-1183
(919) 541-4828
(312) 353-5598
(919) 541-4156
(919) 541-4930
(919) 541-2774
(919) 541-4154
(919) 541-4847
(202) 260-1294
(919) 541-5347
(202) 260-5849
(202) 260-5904
(513) 569-7462
(703) 934-3768
(703)305-6511
(703) 305-5473
-------
7. Update on the RfD for Arochlor 1016: The RfD for Arochlor 1016 was loaded onto IRIS
on January 1, 1993. Industry representatives met with Erich Bretthauer (AA, ORD) on
January 6,1993 to discuss this RfD. Mr. Bretthauer agreed that industry had some valid
concerns regarding the RfD for Arochlor 1016, and recommended that this RfD be sent to the
Risk Assessment Forum who will arrange for an external review of the file.»
8. Update on IRIS Quality Assurance Team (QAT): Annie Jarabek (OHEA/HPA) explained
that the IRIS QAT was appointed by Hank Habicht. The QAT is developing a questionnaire
for various IRIS users (e.g., state and local governments, environmental, and industry groups).
The questionnaire is aimed at establishing how peer review of the information on IRIS might
be accomplished. Work Group members will also be interviewed. A Federal Register Notice
wilf soon be published regarding IRIS (in particular, reiterating how the IRIS Submissions Desk
can be used and discussing the existence and mission of the QAT).
9. Kenneth Poirier passed out a paper by Renwick entitled "Safety factors and establishment
of acceptable daily intakes" from a symposium attended by Mike Dourson (OHEA/STA)
(Attachment 2).
10. Robert Beliles (OHEA/HHAG) stated that he had a problem with the atrazine RfD. He
questioned why the 2-year dog study was used instead of the 2-year rat study. In addition, a
developmental effect was seen at the same dose identified as the critical effect level and
blood dyscrasias occurred in both rats and dogs with the LOEL in dogs being one-tenth of
the rat LOEL, Rick Whiting (OPP) responded that he would bring this file back at the March
meeting so that the Work Group could revisit these issues.
11. A copy of the updated IRIS Reference Dose Background Document was passed out
together with a copy of the memo from the Work Group Chairs to BiH.Fariand requesting that
the updated background document undergo appropriate review and approval for inclusion on
3)rv^
-------
Aroclor 1016
John Cicmanec (OHEA/STA) passed out a memorandum regarding the RfD for Arocior 1016
(Attachment 9). This RfD was verified on November 4, 1992 at 8E-5 mg/kg-day. In the
process of loading this file onto IRIS, an error in the transposition of the NOAEL dose was
noticed. The correct NOAEL is 0.007 mg/kg-day, rather than 0.008 mg/kg-day as written in
the summary sheet. Correction of this mistake resulted in an RfD of 7E-5 mg/kg-day. The
correct RfD was loaded onto IRIS, and the memorandum served to bring the mistake and its
resolution to the attention of the entire Work Group.
9
-------
-------
«,
«,
BRIEFING PACKAGE
MICHAEL DOURSON
TO
JOHN SKINNER
AUGUST 2, 1992
-------
f
Arochlor 1016 Reference Dose
Review Status of the Arochlor
1016 RfD
December 1989: Development of a arochlor 1016 IRIS file for
work group discussion
February 1990: First EPA work group discussion of 1016
April 1990: Arochlor J016 is loaded onto IRIS Service code 8
(i.e., notification of EPA discussion)
March 1991: OHEA notifies interested EPA scientists and
managers and ATSDR of its intent to develop RfDs for
commercial PCB mixtures
, 7
February 1992: OHEA interacts with GE scientists at Region II
- Hudson river site
March 1992: GE scientists send the critical study for arochlor
1016 to OHEA
March 1992: Second EPA work group discussion of 1016
May 1992: OHEA sends the results of its statistical analysis of
the critical study on arochlor 1016 to GE
June 1992: Unanimous EPA work group verification of the
arochlor 1016 RfD
October 1992: Anticipated IRIS load
INTRA-AGENCY RfD/RfC WORK GROUP
-------
*
Arochlor 1016 Reference Dose
Critical Effect: Reduced birth weights
in rhesus monkeys
Studies: A series of developmental and
reproductive studies in rhesus
monkeys by Barsotti and colleagues
No Observed Adverse Effect Level:
0.008 mg/kg/day
Lowest Observed Adverse Effect
Level: 0.03 mg/kg/day
Uncertainty and Modifying Factor:
This factor is judged to be 100.
Reference Dose: 8 x 10(-5) mg/kg/day
INTRA-AGENCY RfD/RfC WORK GROUP '
-------
« Arochlor 1016 Reference Dose
^
uy
UNCERTAINTY FACTORS
for arochlor 1016
VALUE EXTRAPOLATION
3 AVERAGE HUMAN TO
SENSITIVE HUMAN
3 ANIMAL TO HUMAN
3 SHORT TERM TO LONG
TERM EXPOSURE
1 LOAEL TO NOAEL
3 MINIMUM TO COMPLETE
DATA BASE
The composite factor of 100 was judged to
be appropriate by the work group in June
nf1QO9
of 1992.
INTRA-AGENCY RfD/RfC WORK GROUP
-------
*.
Aroclor 1016 Reference Dose —
Confidence in the RfD
The Agency has medium confidence
in the Reference Dose based on ...
medium confidence in the critical
studies since they were well
conducted and evaluated sensitive
endpoints, and
medium confidence in the data base
due to limited toxicity and
reproductive data.
The available human toxicity data are
consistent with the animal findings.
Both together form a plausible
picture of toxicity for arochlor 1016
in humans.
Draft IRIS Language INTRA-AGENCY RfD/RfC WORK GROUP
-------
BRIEFING PACKAGE
GENERAL ELECTRIC
TO
ENVIRONMENTAL PROTECTION AGENCY
AUGUST 2, 1992
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•
-------
18V
CHAPTER SIX
THE UPTAKE AND ACCUMULATION OF AROCLOR 1016 IN ADULT
IHESUS WONKEYS AND THEIR OFFSPRING
It has long been felt that the higher chlorinated the PCB mixtures
the more potent of inducers of enzymatic activity and toxfcity the PCBs
were (Litterst et al_. ,1972; Chen and Dubois, 1973; JoRnstone-efral.,
1974; Grote et al.,1975}. The biologic activity differed Between PCB
mixtures and isomers. The degree of chlorination of the PCBs was re-
* ~* •*•
lated to the fate in the body. The higher the degree of chlorination
the less would be excreted by the body .(Matthews and Anderson, 1975;
Peterson et^a_l_., 1976; Allen and Norback, 1976). Due to tfiis property
of the PCB mixtures a new product was developed that would Be a good
dielectric and heat transfer fluid but contained a lower percentage of
the higher chlorinated PCBs. It was through that these would be less
persistent in the environment. The Aroclor 1016 contains about 41X
chlorine and differs from Aroclor 1242 with its 42X chlortne by weight
by containing only 1/10 the level of penta- and hexachlorfnated B1-
phenyls. In feeding studies comparing the storage and distribution of
*
Aroclors 1016 and 1242, Burse and her colleogues (1974) found that
the adipose plateaus of PCBs were higher in value with Aroclor .1016.
They found that the level of PCBs throughout the experimental period
was higher for Aroclor 1016 in the brain, liver and urine. From studies
with isoraers it has been suggested that the position of the chlorines.
and the unsubstituted carbon atoms Influence the. behavior of PCBs. Un-
substituted pairs of carbons at the 3,4 positions lead to raptt. elintn-
ation of the PCBs from the body (Gage and Holm, 1976).
-------
182
Recently PCS isomers have been classed as two different types of
enzyme inducers: phenobarbital and 3-methylcholanthrene (3-MC) types.
No one isomer can be identified as both types of inducers at this time.
The Aroclor mixtures are composites of both types of inducers (Gold-
stein, 1979). The 3,3',4,4'-configuration of the biphenyl appears to
be I minimum requirement for the 3-MC type -Jnducer which is the-toxic
element of the PCB mixtures (Yoshimura ejt aK, 1979}. Thus the Aroclor
mixtures behave 1n biological systems according to the types of Inducers
that are present and this does not necessarily depend upon the degree
of chlorination but more importantly the position of thfc cElortnes.-r.
TLittle is known about the activity of Aroclor 1016 1n biological
systems. For this reason this reported study was undertaken to eval-
uate: 1} the gross, clinical and reproductive health of female rhesus
monkeys fed diets containing Aroclor 1016 at the levels of 1.0, 0.25^
and 0.025 ppm; 2} the storage of PCBs in the, female, the pregnant
female and the lactating female; 3) the accumulation of PCBs in the
Infants through ^n utero and transmamrnary movement of PCBs and the
effects this movement of PCBs might have on the Infants.
MATERIALS AND METHODS
Twenty-four adult female rhesus monkeys were procured from an im-
porter and placed in quarantine for three months. The animals were
housed 1n rooms whose climatic conditions mimicked that of a 20 day
period in the breeding season of the animals' native India in respect
to temperature, lighting and humidity. During this time the monkeys
were examined dally, given food and water ad libitum and supplemented
with fruit twice weekly. On the day of their arrival 1n the colony
-------
183
and monthly thereafter during the quarantine period the animals were
given intradermal tuberculin 1n the upper eyelid and examined 48 hours
thereafter for any reaction. Body weights were U^n biweekly, hemo-
grans monthly and serum chemistry analyses (serum totll llpld, choles-
terol and glutaraic pyruvate transamlnase j(SGPT)j weri performed every
third month. The mensirual cycles were observed *nd recorded as .to
menstrual cycle length and mensus length and Inttnilty. Once an.anlmal
has demonstrated regularity of three cycles blood Wtl drawn through-
out an entire menstrual cycle to obtain serum for determinations of
17-0-estradiol and progesterone levels (Chapters 2 *nd 4). Eight females
from the "general colony served as controls.
Following the completion of the pretreabnent evictions the animals
were divided.into four groups of 8. Three of the groups were placed
on the diets containing 1.0,0.25 and 0.025 ppta Aroclor 1016 ( < 3 ppb
dlbenzofurans, McKinney, personal communication). The remaining eight
females received diets to which no additional PCS wil *dded. The diet
was prepared by adding the appropriate amount of Aroclor 1016 stock to
the appropriate amount of corn oil to produce 240 ml of PCB containing
oil. This was added to 50 Ibs of ground Purina monkey chow (Ralston
Purina, St. Louis, MO.) and mixed for 10 minutes. To this mixture
approximately 2000 ml of water was added and the chow was pelleted.
The bagged pellets were color coded and labeled with the concentration
of the diet and the date. Samples were taken for analysts *" hexane
rinsed vials and labeled as to diet and date. Tht difts were stored
frozen until used. GC analysis for PCBs on the feed w« employed
-------
184
(AOAC.1975).
After the animals were placed on the experimental diets, complete
blood counts were performed monthly. Serum chemistry assays were done
every third, month. Radioimmurioassays for the levels of 17-£-estrad1ol
and progesterone was performed on the serum obtained after 3 and 6 .:•
months en the experimental diets.
Following the completion of the abovt determinations, atteapts were
made to breed the four groups of-females'to control males during the
appropriate time of the cycle as determined by the length of the pre-
vious mentrual cycle (Chapter 2). The females were housed with the
males for 96-120 hours. This procedure continued until the feaale
became pregnant or the breeding trial was terminated. Serum was taken
from blood drawn 20 days after the mean breeding day. This was used for
•
mouse bioassay for monkey chorionie gonsdotrophin to confirm pregnancy
1n the case of early abortion (Wilson e£ «1_.,1972). Pregnancy was
confirmed by rectal palpation of the uterus at day 35 post-mating.
When the Infants were born they were weighed, abdominal skin biopsies
were taken, and measurements of the head circumference as well -as crown
to rump lengths determined. A maternal skin and subcutaneous fat biopsy
was performed at this time. Similar biopsy procedures were employed
on the mother and Infant after an additional three months. At one week
post-partum and every other week thereafter until the infant was four
months old, the infant-mother pair were separated and a milk sacple
was taken for PCB analysis. In addition the infants were weighed and
hemograras were performed at this time. At four months of age the In-
fants were weaned, they were given a general anesthetic and roesenteric
-------
185
fat was taken at laparotomy (Appendix Vf). In groups of eight, based
on the parturition date, the animal were removed from the diets and
subcutaneous and mesenteric fat was taken by laparotomy.
A complete necropsy was performed on all animals that died during
this project. Tissues were fixed in neutral buffered formalin, dehy-
drated, embedded in parafift'- and sectioned at 5 v» Following -deparaf-
fination, the tissues were stained with hematoxylin and eosin and ex-:
amlned by light microscopy. In addition, liver,' adipose and adrenal '
samples were taken for PCS analysis.
RESULTS
At the time of arrival the female monkeys appeared healthy. This
was substantiated by their normal hematology and serum chemistries,
and the absence of positive tuberculin reactions. Some the animals
appeared younger than others. This was further clarified by the Ir-
regularities in their menstrual cycles. As a result of this Immaturity
nine oonths in the controlled experimental environment were required
for all the animals to establish a regular menstrual cycle.
The 6C analyses of the four diets for Aroclor 1016 content were
0.700±0.130 pg/gm, 0.164+0.031 v9/gn>» 0.023+0.001 yg/gro and O.OOSi
0.001 vg/gm in the 1.0 ppm, 0.25 ppm, 0.025 ppm and control groups,
respectively. Purina monkey chow has been found to contain 1-50 ppb
Aroclor 1248. Ltrait of detection for feed was CUOQ5 yg/gro-,
Control adipose samples contained PCBs based on Aroclor 1016 stand-
ard at the level of 0.69*0.38 vg/gm on the lipid basis. Three animals
sampled had adipose PCS levels below the limit of confident detection
for this analysis.
-------
186
amount of Aroclor 1016 accumulating in the subcutaneous tissues
of the animals was 2.-16+1.10 vfl/gm. 1.30*0.83 vg/gm and 0.29*0.14 pg/
gm after four months on the experimental diets and 5.03±3.45 vg/gm»
1.61±0.43 pg/gra and 0.35±0.16 yg/gra after seven months on the diets
for the 1.0 ppm, 0.25 pptn and 0.025 ppm groups,respectively (Table 6-1).
It was at this time that a contamination peak was noticed 1n the" GC ..
analysis for the samples 1n the 0.025 ppra Aroclor 1016 group. .This
contamination was determined to be polybrocnlnated blphenyl .(PBB)." It was
concluded that the 0.025 pptn Aroclor 1016 group received PBB diets for
a undetermined time due to a mix up at the pelleting site. • Due'to. this
unfortunate situation the procedures at the pelleting operation were
changed to avoid future reoccurrence of such a situation. For the
purpose of this report the 0.025 ppra Aroclor 1016 values will be re-
ported but tMs contamination by PBB will be considered.
Prior to breeding there were no changes 1n the food Intake, general
appearance, hemograras or serum chemistries. In addition the menstrual
cycles of the animals were unmodified as a result of the PCS exposure
(Chapter 2). The levels of the circulating serum estradiol and pro-
gesterone during the third and sixth month of the experiment were de-
termined to- be similar to those recorded prior to the administration
of the diets containing PCBs.
After having consumed 8.8±1.9 mg of Aroclor 1016/kg of body weight
1n the 1.0 ppm group, 2.0±0.4 mg/kg in the 0.25 ppra group and 0.20 ±
0.0 ng/kg 1n the 0.025 group, the animals conceived following one to
five breedings (Table 6-2) The reproductive capability of this group
-------
. w
1s discussed in Chapter 2.
In addition to the maintainance of normal hemograms and serum chem-
istry levels, these animals had uncomplicated pregnancies. One animal
from the 0.025 ppm group had a stillborn Infant that resulted fron
malpresentation of the Infant. This was not considered to be statisti-
cally significant when compared to other experimental and control~groups
front the colony (Chapter 2) nor was 1t considered PCB or.PBB exposure
related. There were no gross or oicroscoplc changes In this stillborn
Infant that were attributable to PCB or PBB exposure. The analysis
of the stillborn** tissues for Aroclor 1016 showed transplacental nove-
ment of this compound. This was also true of PBB. The adipose tissue
contained 0.60 pg/gm Aroclor 1016 and the other tissues revealed the
characteristic 1016.patterns, but the quantltatlon was oat^posiible.
At birth the Infants of the 0.25 and 0.025 ppm groups were similar
in size and weight to those of the control Infants (Table 6-3). The
Infants of the 1.0 ppm females had birth weights significantly less
than the other infants as determined by Student's t test (p<0.05).
Samples of the infant skin taken at birth showed levels of Aroclor
1016 on the lipid basis from 3.37±n.76 ppm in the 1.0 ppm group, 1.65*
0.84 ppra in the 0.25 ppm group and only trace amounts In the lowest
dose'group (Table 6-4). Maternal fat samples (lipid basis) had 2.92±
0.70 vg/gm» 1.29±0.53 pg/gra and 0.73+0.78 wg/gm Aroclor 1016 In the
1.0, 0.25 and 0.025 ppm groups, respectively. (Table 6-1). The levels
of Aroclor 1016 in the adipose tissues of the Bothers were similar
after four and seven months on the diets and at parturition. Mesenteric
fat samples taken when the adult females where removed from the diets
-------
188
and their Infants at weaning contained considerable PCBs. The samples
obtained from the 1.0 ppm mothers contained 4.30+1.50 ppra PCS (lipid
basis) while their infants' mesenteric fat contained 27.54±7.19 ppra
PCB (lipid basis). The 0.25 ppm mothers showed levels of 1.50±0.53
ppra (lipid basis) their infants showed levels of 10.39*3.69 ppm PCB
(lipid basis). The 0.025 ppm group was considerably lower (Table ^-1
and 6-4). Milk fat levels of PCB obtained biweekly throughout the four
hionths of nursing averaged 3.44±0.31 ppra, 1.47±0.37 ppra and trace levels
for the 1.0, 0.25 and 0.025 pom groups, respectively (Table 6-5).
When the adults were removed from the experimental diets'no "gross
hematological or clinical chemistry alterations Mere observed (Table*
6-6 and 6-7) The animals maintained normal food consumption and body
weights throughout the experimental period (Tables 6-2 and 6-8).
During the four months of nursing all the Infants showed consistent
weight gain .however, the Infants from the 1.0 ppm group did not attain
body weights equal to those of the other groups (Table 6-3). In addi-
tion to the differences in weights four of the eight Infants froo the
1.0 ppm group developed marked hyperpigmentation of the skin about the
hairline of the face and down the middle of, the scalp. Similar changes
1n skin color were observed In the other two groups to varying degrees.
Hematological determinations conducted on the infants during the course
of nursing were similar to those recorded in the control infants (Table
6-9). The total Intake of Aroclor 1016 by the adult females at the
time the Infants were weaned was 19.U4.4 mg/kg for the 1.0 ppm group,
4.6±0.6 ng/kg for the 0.25 ppm group and 0.5±0.1 mg/kg for the 0.025
ppm group (Table 6-2).
-------
189
Analysis of Aroclor 1016 levels. 1n the tissoes of the adults and
infants as well as the mother's milk Indicated trmplacental and
mammary movement of the PCBs. The accumulation of Aroclor 1016 in the
adults did not include the total spectrum of peaks observed in the
Aroclor 1016 standard (Figure 6-1). There MS a preferential accumula-
tion of three peaks with relative retention tfees (HZT) of 37. 47 .and
70 (relative to DDE) representing approximately 901 of the Aroclor 1016
present (Figure 6-2). "These three peaks represent approximately 451
of the standard.for Aroclor 1016.
The infants.at- birth showed an accumulation of all the Aroclor 1016
peats in their skin. The peaks with RRT's of 37, 47 and 70 comprised
the uajority of the PCB's representing approxinately 801 of the Aroclor
1016 present. By the end of the nursing period (four »onths of age)
mesenteric fat biopsies from the infants showed an accumulation of
Aroclor 1016 peaks similar to that in the adults (Figure 6-3). However.
the contribution of the peaks with RRT's of 37 and 70 was greater in
the infants than the adults. These two peaks represented approximately
805 of the total Aroclor 1016 present in the infants as compared tc
approximately.601 in the adults. The peak with RRT of 47 comprised
only 5-101 of the Aroclor 1016 in the infants but comprised approxima-
tely 251 in the adult. Four months after weaning the pattern of Aroclor
1016 peaks in the jnesenteric fat of the infants was similar to that
observed at the time of weaning although the total levels had decreased
(Table 6-4).
The analyses of milk samples indicated that almost til of the Arpclor
1016 peaks were excreted via this lactational process (Figure 6-5).
-------
190
The relative quantities of the Individual peaks were different from the
standard with peaks with RRT's of 37 and 70 representing a greater per-
centage of the total.
In almost, all of the GLC analyses, two peaks with RRT's of 125 and
146 were observed (Figures 6-2,6-3,6-4). These peaks cochrooatographed
with two of the major peaks observed 1n commercial mixtures of higher
'chlorine content. These peaks were also seen 1n samples from control
animals (Figure 6-6). In «n1lk samples, these peaks were frequently
masked by a large peak presumably due to I1p1d which was not removed
during cleanup procedures (Figure 6-5).
DISCUSSION
In the past 1t has been proposed that the lower chlorinated PCS
mixtures such as Aroclor 1016 would be nore rapidly metabolized and
thus be less toxic than the higher chlorinated mixtures. There are
Indications from the presently reported study that the response of
monkeys chronically exposed to low levels of Aroclor 1016 are similar
to those observed when low levels of. Aroclor 1248 was employed (Chapter
5). Thus H would appear that there are circumstances were the toxic
manifestations produced by the lower chlorinated PCB mixtures are sim-
ilar to those caused by the mixtures comprised of more highly chlor-
inated species.
The preferential accumulation of the 3 peaks presumably Indicates
the ability of the nonhuman primate to metabolize and excrete some of
-the compounds in the Aroclor 1016 mixture more readily than others.
The accumulation of the peak with RRT Is surprising based on the 1den-
-------
191
tificatton of this peak as a trichlorobiphenyl by Sawyer (1978 a,b).
All previous studies have Indicated that trichlorobiphenyls are read-
ily metabolized and excreted by birds and mammals (Matthews et al.»
1978). A recent report of the Yusho women exposed to the contamina-
ted rice oil indicated thatthe'ailk contained PCB residues with tri-
and tetrachlorinated species. The specif 1c .-structure, of the residual
conponents was 4,4'-substitut.ion pattern (Yakushiji e£ al_.,1979)..
The identification of almost all of the Aroclor 1016 peaks in the
skin of the neonates presumably indicates the inability of the fetus
touetabolize the compounds which are .easily metabolized in adults
and older infants. This conclusion is further substantiated by a
loss of these peaks in the infants even while nursing. The decrease
in Aroclor 1016 levels in the infants after weaning is not readily
explained. Based, on the accumulation of certain peaks in the adults
it would seem unlikely that extensive metabolism of these peaks would
occur in the infants. This possibility cannot be ruled out. However,
another explanation may be that the decrease in PCB concentration may
be due to an increase of size with e subsequent dilution of the PCBs
without excretion. A third possible explanation for these findings
•is that during the rapid period of growth, the dynamic shift in major
anabolic pathways may alter the storage, distribution and elimination
of the PCBs. The understanding of these results is further complica-
ted by the differences observed in relative quantities of certain
peaks between the infants and adults. The importance of the accum-
ulation or metabolism of certain compounds on the toxic effects that
-------
192
are Induced in these animals cannot be evaluated on the basis of the
information that is available.
Of particular interest is the finding of the multiple peaks of
Aroclor 1016 In the mothers' milk. This observation way Indicate
that ingested PCBs are readily transferred to milk fat during periods
of heavy lactation before significant metabolism can occur. The'pos-
sibility that in utero and mammary exposure of the.infants to the
compounds that are readily metabolized by the adult may have causative
relation on the intoxication that developes in the infant. Studies to
date have not elucidated the compounds responsible for toxicity in.
the mixtures that are employed. In the light of.Goldstein's (1979)
and Yoshimura's -(1979) observations as to the nature of the isoraers
present in the mixtures,identification of the isomers with the RRT's
mentioned previously and their classification as to the type of fndo*
cers would be important. This information is presently being sought.
The finding of higher chlorinated PCBs in control and experimental
samples is not surprising since PCBs have been shown to be ubiquitous
in the environment. They have been found 1n commercial monkey chow
also (Coleman and Tardiff, 1979). We have shown that the concentra-
tion of PCBs in control monkey show 1s in the range of 1-50 ppb on
the basis of an Aroclor 1248 standard. Incidental findings of.PCB
levels up to 1.0 ppm in fat samples of monkeys from our. colony are
not unusual. These levels however did not affect Infants from con-
trol animals or the reproductive capabilities of the adults (Chapter
2). These may be nontoxic congeners which are stored 1n the adipose
-------
193
tissue of mammals.
In contrast to the severe signs of Intoxication observed in the
infants that received larger doses of PCBs (Chapter 5} the adult
females which were employed in the present study did not show any
overt signs of PC6 intoxicatibn. In addition, their general body
health,'food consumption, body weights, hematology, 'serum chemistry
and reproductive processes were -unaltered -when coraped>withvtfie:eon-.;
trol monkeys from our colony (Chapter 2). The unfortunate PBB con-
tamination of the 0.025 ppn PCB group did not appear to alter any of
the toxic parameters, However, this cannot be concluded until the'
behavioral evaluation of the infants is completed. ';•
Even though the adult animals were normal in all of the para-
meters evaluated such was not the case with their infants;. In addi-
tion to the 1.0 ppn PCB infants being smaller and showing difficulty
tn weaning (one infant died from the stress of maternal separation)
Six of the 8 infants of the. 1,0 ppra group, 1 of the 8 infants of the
0.25 ppm group and 2 of the 7 infants from the 0.025 ppm group devel-
oped hyperpigmentation. These changes were similar to those described
in the infants that were exposed to Aroclor 1248 (Chapter 5).
It appears that levels of Aroclor 1016 which range from 1.0 to
0.25 ppm ( the 0.025 ppm group would be excluded from this discussion
for the above stated reasons) will not produce any overt signs of
intoxication even when the period of exposure exceeds 18 months in
the adult female monkeys. However when infants are born to these
seaingly normal adult monkeys,they will exhibit manifestations of
-------
194
Intoxication. There Is sufficient PCB exposure via transplacental
and secretion during lactation by the mothers to produce signs of PCB
intoxication in the infants. The highest level of PCB consumption
ocdr during the four months of nursing with a concomitant increase
fn body burden of PCBs.
The effects of PCB accumulation 1n ths tissues of the Infants are
subtle and wild manifestations.of Intoxication could be qverlooked
easily if they ocurred fn a colony were these particular parameters
were not being evaluated optically.
In the light of the ubiquitous distribution of PCBs in our en-
vironment at the present time, their presence 1n the food chain, of
human consumption, their detectabillty 1n ppm concentrations 1n the
hunan ad'ipose tissues and the manifestation of experimental Intoxica-
tion of primates at dose levels of ppb, it would seen that judicious
concern needs to be afforded to this Important environmental contam-
inant. This study suggests such evaluation will probably require more
exacting procedures than are presently available to detect minimal
and symptoms of Intoxication 1n animals and nan.
-------
195
FIGURE 6-1 Gas chroroatographic tracing of 1 ng Aroclor 1016 FDA "
standard 1151 C77029). Attenuation - 64, Temperature «
200° C. The numbers assigned to the peaks designate the
relative retention times with reference to p.p'-DDE as
100.
-------
196
FIGURE I
r
-------
197
FIGURE 6-2 Gas chromatographlc tracing of a subcutaneous fat sample
from monkey *79 after receiving Aroclor 1015 in the diet
at 1.0 ppm for 18 weeks. Attenuation « 8; Temperature »
200°C. The numbers assigned to the peaks designate the
relative retention times with reference to p,p'-DDE as
100. The level of Aroclor 1016 on the whole tissue basis
was 2.27 pg/gm and 3.25 vg/gm on a lipid basis.
-------
198
FIGURE I
-------
FIGURE 6-3 Gas chromatographic tracing of a mesenteHc fat sample
taken from monkey /79's infant AG-81 (1.0 ppm Aroclor
1016) at the time of weaning from the Bother. Attenua-
tion « 32; Temperature * 200° "C. The numbers assigned
to the peaks designate the relative retention times with
reference to p,p'-DDE as 100. The level of Aroclor 1016
on a whole tissue basis was 10.43 pg/gra and 31.31 pg/gm
on a lipid basis.
-------
200
FIGURE 3
-------
FIGURE 6-4 Gas chromatographic tracing of a mescnterlt fat sample
taken from monkey #79's Infant AG-81 (1.0 ppm Aroclor
1016) four months after weaning from the mother. Atten-
uation = 8; Temperature * 200° C. The numbers assigned
to the peaks designate the relative retention times with
reference to p.p'-DDE as 100. The level of Aroclor 1016
on a whole tissue basis was 1.96 yg/gm and 2.96 ug/gm on
a llpld basis. Note that peak 47 has been partially
resolved Into two parts when compared to Figure 6-3.
-------
202
FIGURE 4
-------
203
FIGURE o-5' Sas chromatographic tracing of a milk sample taken frcra
monkey 179 (1.0 ppm Aroclor 1016} during tfie nursing
period. Attenuation e 8; Temperature « 200° C. The
numbers assigned to the peaks designate the relative
retention times with reference to p.p'-DDE as 100 The
level of Aroclor 1016 on a whole milk basis was 0.11
pg/gm and 2.99 ng/gm on a lipid basis.
-------
204
name s
j—i—i—i—«-H—«—I t. 1—«—I-
-------
205
FIGURE 6-6 Gas chromatographic tracing of a subcutaneous fat sample
taken from monkey #33 (control) at parturition of her
infant. Attenuation = 16; Temperature = 210° C. The
numbers.assigned to the peaks designate the relative
retention times with reference to p.p'-DDE as 100. The
level of Aroclor 1016 on a whole tissue basis was 0.36
vg/gm and 0.40 vg/gm on a lipid basis.
-------
FIGURE 6
206
-------
207
TABLE 6-1 Levels of PCBs (Fat Basis) in the Adipose of Female Konkeys
Consuming a Diet Containing Aroclor 1016
diets
1.0
0.25
U.U25
Control
After 4 mo.
on diet
(pg/gm)
2.16±1.10
1.30+0.83
(n=8)
0.29+0.14
C«-5)
After 7 mo.
on diet.
(pg/gm)
5.03±3.54
(n=6)
1.61+0.43
(n=6)
0.35±0.16
(n-6)
At parturition
(pg/gm)
2.92+0.70
(n=8)
1.29±0.53
-------
208
TABLE 6-2 Intake of Aroclor 1016 by Adult Female Rhesus Monkeys
Level in
diet
(pg/gm)
1.0
0.25
0.025
Intake after
7 months
(mg/kg)
6.H0.9
1.7±0.3
0.2iO.O
Intake at
Conception
(mg/kg)
8.9±1.i
2.0±0.4
0.2iO.O
Intake at
Parturition
(mg/kg)
10.812.1
2.610.3
0.310.0
Intake at
Weaning
(rag/kg)
18.U3.1
4.510.6
0.510.1
Values = Heansil standard deviation
-------
209
TABLE 6-3 Weights and Measurements of Infants whose Mothers were
Exposed to Aroclor 1016. prior to and durfng Pregnancy
and Lactation
Level in
diet
(yg/gm)
1.0
0.25
0.025
Control
Height at
Birth
(gm)
422±27
491 ±23
489±54
512±64
Weight at
17 wks of
age (gm)
864±97
939±72
939±59
896±90
Head
Circumference
(on)
19.U0.51
1 9.3±0.45
19.2±0.47
19.5±0.50
Crown to Rump
Length
(on)
15.7±0.9
16.5±0.8
16.9±1.0
16.8il.3
Values s Means* 1 standard deviation
-------
210
TABLE 6-4 PCB Levels (Fat Basis) in the Tissues of Infants whose
Mothers Consumed Aroclor 1016
Level in Diet At Birth Skin 4 mo. of Age 8 mo. of Age
Hesenterlc Fat Hesenteric Fat
(pg/gra) (pg/gm) (yg/gm)
1.0
0.25
0.025
Control
3.37+0.76
(n=8)
1.65±0.84
(n=7)
*0.23
(n=3)
***1.0.;2.07
27.5U7.19
(n=8)
10.39±3.69
(n=8)
2.74±0.47
(n=7)
3.75±1.00
(n=5l
1.96+0.54
Cn=5]
**0. 61+0.30
Cn=6)
0.46+0.16
Cn=6l
*2/3 samples were below the limit of detection for thfs analysis
(0.02 yg/gm)
** 1/6 samples was below the limit of detection for thfs analysis
*** 4/6 samples were below the limit of detection for this analysis
Values e Means 1 standard deviation
-------
211
TABLE 6-5 PCBs in Breast Milk (Lipid Basis) from Female Rhesus
Monkeys that have Consumed Diets Containing Aroclor 1016
Level in During 1st During 2nd During 3rd During 4th
diet mo. lactation mo. lactation mo. lactation mo. lactation
(jig/gm) (pg/gm) (vg/gm) (vg/gm) (vg/gm)
1.0
0.25
0.025
Control
3.00±0.60
(n=8)
1.08+0.35
(n=8)
*0.69
(n-6)
***0.49,0.45,
1.07
(n=8)
3.7010.94
Cn-7)
1.23+0.17
(n=8)
N.D.
(n=6)
0.94
(n=8)
3.46±1.19
(n=8)
1.7410.53
(n=8)
N.D.
(n=6)
****0.62,1.02
(n=8)
3.6010.88
(n=8)
.1.8310.75
(n=8)
**0.48
(n=7)
****0.40,1.06
Cn=8)
*5/6 samples were below the level of detection
** 6/7 samples were below the level of detection
*** 5/8 samples were below the level of detection
**** 6/8 samples were below the level of detection
N.D.» not detectable, below the level of detection (0.02
Values * Heansil standard deviation
-------
212
TABLE 5-6 Hemograms of Female Monkeys Exposed to Aroclor 1016 for
Approximately Twenty Months
Level 1n Hematocrit Hemoglobin White Blood Cell
diet *
(Vg/gm) X (s/dl) (x 103)
Initial20 monthsInitial20 monthsInitial20 months
1.0 38±5 4U3 12.6+1.7 12.8±0.9 7.6±2.5 8.2±1.5
0.25 41±2 40±2 13.5±0.6 13.4±1.3 11.2±4.2 .8.9±2.4
0.025 36±7 40±2 12.U2.2 12.5+1.2 11.2±2.5 8.3±2.6
Values = Meant! standard deviation
-------
213
TABLE 6-7 Serum Chemistry Determinations of Female Rhesus Monkeys
Exposed to Aroclor 1016 for Approximately Twenty Months
Level in Total Lipid SGPT Cholesterol
diet (vg/gm) (mg/dl) (units) (mg/dl)
•Initial Final Initial Final Initial Final
1.0 4 33 ±70 415±133 9.4+9.1 13.3±6.8 150±32 162+11
0.25 460±103 390±94 17.6±7.5 11.4+3.2 155+33 156±41
0.025 428+79 446±123 15.3+8.4 14.3±5.5 136+25 140+21
Values * Kean+1 standard deviation
-------
.214
TABLE 6-8 Body Weights of Adult Female Rhesus Monkeys that Consumed
a Diet Containing Aroclor 1016 for Approximately Twenty
Months
Level In. diet Initial Body Weights Body Weight after
Weaning
(kg) (kg)
1.0
0.25
0.025
5.04±1.07
4.88±0.60
4.85±0.76
5.18±0.95
5.47+0.80
5.30±0.75
Values « Meant! standard deviation
-------
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-------
19 '84 39;49 ECftO CIN FST Pt2
Date : April 6,1991
To : Dr. John L Cicmanec,
ECAO
From : Amy Feng, Sr. Statistician
Computer Sciences Corporation
Subject: Statistical Analysis of PCS (1016) Dosed Monkey Birth Weight Data.
Results : A statistically significant difference in birth weights was found
between control and high dose (1000 ppb) groups (p=0.003). A
statistically significant difference was also found between sex birth
weights regardless of dose (p-0.0496). No statistically significant
difference was found in birth weights among gestation length
(p=0.675).
The PCB (1016) dosed monkeys' birth weight data were analyzed using a two-
factor (sex, dose) analysis of variance (ANOVA) followed by Tukey's multiple
comparison procedure to test for a dose-related effect. Initially, gestation length
and the monkey sire ID were included in the ANOVA model. Gestation length
was not reported for the control group. Therefore, a three way (SEX, DOSE,
SIRE ID) ANOVA with gestation days as covariate was performed for only the
dosed groups. No statistically significant effect of gestation length was detected.
Then, the ANOVA model including DOSE, SEX, DOSE*SEX, and SIRE ID was
tested. No statistically significant difference was found for SIRE ID and the
interaction DOSE*SEX. The final model, then, included only DOSE and SEX as
explanatory variables for the dependent variable, birth weight.
The necessary assumption of ANOVA procedure was tested and met; Bartlett's
statistics for the homogeneity of variance and Shapiro-Wilk statistics for the
normality of data.
Tables of summary statistics and test results are included. Please let me know
if you need further information.
cc. RH
LK
-------
-------
MfiY 19 "34 09:58 ECAO GIN FST
P. 3
PCB (1016) Dosed Monkeys' Birth Weight Data
Table 1. Summary Statistics
Dose (ppb)
0
25
250
1000
F
M
Mean Birth
Weight
521.11
465,00
491.25
422.5Q
463.33
502.67
N
9
8
8
8
18
15
STD
64,60
60.42
24.18
28.91
48.51
64.34
MAX
535
560
525
480
550
595
MIN
400
380
450
385
380
385
Table 2. Analysis of Variance
Factor
SEX
DOSE
GESTATION LENGTH
SIRE ID
DOSE-SEX
ANOVA*
p-value
Q.04961
O.OQ251
0.6752
0.1563
0.2913
Tukey's Multiple*
Comparison Procedure
F M
1000 25 250 0
— __ _
41
* Two-tailed p-vaiue from analysis of variance (ANOVA).
Dose (SEX) groups connected by solid line are not statistically different
(a=0.05). Dose (SEX) groups are arranged in order of increasing mean
birth weight.
1 Two-way (SEX, DOSE) ANOVA, no interaction term included.
2 Three-way (SEX, DOSE, and SIRE ID) ANOVA, gestation length as
covariate, no interaction term included, excluding the control group.
3 . Three-way (SEX, DOSE, and SIRE ID) ANOVA, all interaction terms
included.
-------
19 '94 09:51 ECfiO CIN FST
w, HAQISON j 3-*?-S2
J PRIHATS LABORATORY"
P.4
5135837475J* 2
FOB {1016} Subjact* In 1978 Experiment
Subjtct Sox
No.
Control*
DOB Birth Wt Qast
(daya)
Mdtbar Fcthar
AQ09
AGB5
AQ86
AQ68
AQ70
AQ71
AQ74
AQ88
AQ96
tppm
AQ81
AfiBS
AQ90
AG92
AQ93
AHQ2
AH05
AH14
250ppb
AG77
AG79
AQ87
A<394
AG97
AH03
AH04
AH13
25ppb
1-1
AQ78
AG80
AGB3
AQ64
AG69
AQ99
AH09
r
M
F
F
M
M
M
M
*
F
F
M
M
F
M
F
F
F
F
F
F
F
M
F
M
M
M
F
F
M
F
M
M
4/22/76
4/23/78
4/28/78
5/3/78
5/4/76
5/8/78
£27/78
8/1 a/78
9/28/78
7/7/78
7/2B/7S
6/30/76
9/2/78
9/1/78
10/6/78
10/18/78
12/19/78
5/27/76
7/B/7S
6/9/78
9/14778
9727/78
10/12/78
10/14/73
12/5/78
6725/76
7/5/78
7/1/78
7/22/76
7/25/78
6/29/76
9/26/76
11/14/78
510
666
550
400
480
595
495
570
446
430
410
480
385
440
405
425
406
480
495
470
615
495
450
525
500
k-
640
535
360
475
470
490
590
430
f
f
f
f
*
f
*
*
f
159
164
164
152
165
183
189
151
189
163
162
171
J66
164
161
165
155
166
164
173
167
167
181
162
PP12
PP13
PP14
PP18
PF33
PP37
PP46
Pl»74
PP66
PP70
PP88
PP89
PP70
PP87
PP76
PP81
PP64
PP83
PP82
PP56
PP75
PP62
PN7
PP72
PP78
PP77
PP69
PP64
PP80
PP73
PP86
PPS8
PP06
PP02
PP01
1630
PPOS
PP02
1630
PP06
PP02
1632-
PP01
PPQ5
PP02
PP05
PP01 <3>
PP04
PP04'
PP03
PP01
PP04
PP06
PP03
PP03®
1632 **
PP06
1632 **
PP06
1632 *"
PP06
PP06
PP06
PP05
PP06
dtscl 1/3/79
stilt-birth
* Father 1630 rtctfvtd 5ppm PCB (1246) In (fl«t (12/1/73 -1/13/75}, tetol of 450 m* PCB
**Fathir 1632 raetlvMl Sppm PCB (1248) In dltt (12/1/73 - 4/28/75). total not eateufettd
f Gtttstion dttt for IndlvkJual control 8§ havt not bun found, Howaver, a Blotroo r«eord
(whart thay wart bom) flJvw • maan of 164.7 day* with a ttandard daviatlen o'f ±3,5 days.
<8> AH02 & AH03, (Titad aa tamalaa at Blotren, ravtalad at maitt at tha Prfmat*
-------
MAY 19 '94 09=51 ECHO CIN FST
P.5
PCB (1016) Dosed Monkey Birth Weight Data
BRTHUT
560 1
550 1
540 H
530
520
$10
SCO
490 1
480 I
470 1
460 I
450 H
440 n
430 1
420 -1
1000
-------
MfiY 19 '94 10--S5 ECflO CIN FST
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
HEALTH EFFECTS RESEARCH UBOFWTORY
RESEARCH TIMNSUE PARK. NC 27711
RCSEMWH ANPOEVaCPMENT
-Kay 20, 1992
Rf D for Araclor 1016
R,C. MacPhail, Chief
Heurdbehavioral Toxicology
3Mu Cioaanac, M«nber
JfcCD Workgroup Cojaioittee
X have carefully read the Materials you supplied on the
proposed RJD for Araclor loifi* While in general z agree with tbe
derivation of the S£D and appraisal of th« mpportlng lltaratur*r
2 do !have *oma spacifie eonanents to make • r«gardi3ig the package.
First , there is an iqcott«i«tajicy in the body-walgfet- dRtat^
tlia infanta bojm to mothers deposed" to ' l.'0""pp& Axracleir'idici* Xho
Barsotti and van Miller (1984) paper states that the n*aa weight
iSMMi'422 ± 29 y».. £ could not find in that artieia whether tue
variability 'im'aaaure vaa an SS or SO. In scj^aatz at al» -(ISM) ,
hovftver, the veight is ^iyen as. -442 ± 29 g. While here.;' 'tew;- 'th
variability esfeinate is' uncertain, tth* Ilrst experinen-t in
sehants et 9!. (1989] on Araclor 1248 presents birth weights as
wean ± SD. I believe therefore the variability estimates are
BD», hut cannot he certain. This doee not resolve the problem,
however, of discrepancies in the birth weights ef the 1.0 ppja-
exposed Tjonkays in the two publications.
Pleaee also note that the dose rates given en p. 2 o£ the
&£D write-up are slightly different from these hased on th« data
given in S chant « et al. (1989; see p. 2
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MSY 19 '94 10:55 £CAO CIN FST
P.3
As regards the Levin et al. (1988> seaalts, ^tttfllittt±. *
dose nor the high-doae Airaalor 10i6-e*p«*ea TOi*«^««sSia*fiatti
control* In the delayed spatla^ altearnation taafc, but the two
groups differed fro* each other. Accuracy was significantly
high«r in the low-dooV wohkeys/ suggesting a ttipbaaic »f£«et;JoS
Araclor 1016 on p«r$ermaaee accuracy. Xt «nould be acted that
biphaaic effects ara not uncom&OR in n.eurobohayiezal toxicology;
th* authors rapott*fi obtainiji? « *i»L«- .*ipb««io
_,.
v£th l«ad. ? It is, however, g«a»rally cl?nai<3«red inappropriate to
in
1 conclude "that such an affact axifltc in the .absano^ of
»tati-ert4.aally.r«liable tr«atnant diff«r«nce« from
"
therefore agree with your appraisal "of •tth« results of this study.
As a. minor point, however , it should be noted en p. 3 that the
authors believed the greater accuracy in the low-aose aonkey was
also due to an attentienal deficit (!.«., they attended to fewer
irrelevant stimuli and therefore performed the task more
accurately than controls) . .
Finally, i£ the high doae from Sebants et al. (1989) is
accepted «s th« LOAEL, wouldn't the low dose be, by definition r
the MQABL?
I hope these comaents are useful. Z must say that I
the«c difficult ftrtic3.es to "digest,11 as key pieces of data were
left out of many of the papers and could only be gotten by cross-
referencing the papers, It is not clear to ae how many
experimental animals were studied in all the tests that have been
published! Please do not hesitate to contact me if I may be of
further service.
cc: &. Ball
H. Tilson
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1
^ ? UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
r OFFICE OF RESEARCH AND DEVELOPMENT
ENVIRONMENTAL CRITERIA AND ASSESSMENT OFFICE
CINCINNATI. OHIO 45268
May 12, 1994
Us. Claire W. Stine
Mail Stop 8101
U.S. EPA
401 M St., SW
Washington, D.C. 20460
Dear Ms, Stine:
In preparation for the Aroclor 1016 Workshop which will be
held later this month I would like to provide information regarding
normal body weight ranges for adult female rhesus monkeys (Macaca
TOulatta) as well as birth weight data for infant female and male
rhesus monkeys.
The sources I have been able to draw from are data collected
at Litton Bionetics Kensington, MD. , a commercial animal research
laboratory where I was employed from 1972 to 1982, and the
Wisconsin Regional Primate Research Center which includes some data
for the Biotron facility where the Barsotti studies were conducted.
laboratory Adult Females Birth Weights Birth Weights
Females Males
(kg.) (gms.) (gms.)
Litton 5.1 +/-1-2 474 +/~54 504 +/-23
Wisconsin 4.5-7.5 (range) 4ss +/-4S 494 +/-30
5 . 3 (mean)
The data sources for the Litton Bionetics material are
"Management of a Laboratory Breeding Colony Macaca mulatta" . D.A.
Valerio, R. L. Miller, J. R. M. Innes, K. D. Courtney, A. J.
Pallotta and R. M. Guttmacher, Academic Press, New York, 1969.
and some study reports that I had available. These data are taken
from approximately 400 breeding females and 3000 laboratory-born
infants. The information for the Bionetics colony was obtained for
a period prior to and concurrent with the Barsotti study. The
source for the Wisconsin data are personal conversations with Dr.
Dan Houser, the veterinarian for the Wisconsin Primate Center. At
the time of -the Barsotti study, the Biotron facility was not under
Dr. Houser «s care but for a later period it was under his care,
therefore this information is for a later period than the Barsotti
study. The data is taken from representative groups of monkeys but
not all breeders and newborns for the- Wisconsin Primate Center and
the Biotron facility. I realize that this information does not
Printed on Recycled Paper
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pertain directly to Biotron colony averages at the time of the
Barsotti study but it is the best that I can obtain and it should
serve as some basis for comparison with the experimental test
groups.
icerely yours,
/dohn L. Cicmanec, D.V.M.
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Publications Made Available to Technical Reviewers
D. Barsotti and J. van Miller. 1984, Accumulation of a
commercial polychlorinated biphenyl mixture (Aroclor 10X6) in
adult rhesus monkeys and their nursing infants. Toxicology,
30: 31-44.
E. Levin, S. Schantz, and R. Bowman. 1988 Delayed spatial
alteration deficits resulting from perinatal PCB exposure in
monkeys. Archives of Toxicology, 62: 267-273.
S. Schantz, E. Levin, R. bowman, M. HeironimuS, and N. Laughlin,
1989. Effects of perinatal PC? exposure on discrimination-
reversal learning in monkeys. Neurotoxicoiogy and Teratology,
ll: 243-250.
S. Schantz, E. Levin, and R. Bowman. 1991. Long-term
neurobehavioral effects of perinatal polychlorinatsd biphenyl
(PCB) exposure in monkeys. Environmental Toxicology and
Chemistry, 10: 747-756.
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APPENDIX E
PREMEETING COMMENTS
E-l
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United States
Environmental Protection Agency
Technical Review Workshop on
the Reference Dose for Aroclor 1016
Premeeting Comments
Washington, DC
May 24-25,1994
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TABLE OF CONTENTS
Premeeting Comments:
Henry Anderson
Douglas Arnold
Thomas Burbacher
Peter deFur
Mari Golub
Rolf Hartung
Nancy Kim
Ralph Kodell
t
Philip Leber
John Moore
James Olson
Stephen Safe
Richard Seegal
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Premeeting Comments
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Henry Anderson
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Henry A. Anderson, M.D.
Technical Review Workshop on the Reference Dose (RfD) for Aroclor 1016
Pre-Workshop Comments
April 26, 1994
Parti
Element 1: Selection of Principal Study
While perhaps obvious to some, it would be useful to have a statement on why an Aroclor 1016
RfD is needed. In the concluding paragraph in the "Confidence" section the suggestion is made that it
will be of limited utility and the confidence in the RfD is only medium apparently because it is assumed
it will be used as a surrogate for assessing the toxicity of matures of PCS.
Since the decision was made to evaluate whether it was possible to develop an RfD, the initial
decision must be made whether there are sufficient studies of Aroclor 1016 to adequately characterize
chronic toxicity and quantitatively derive an RfD. I found the studies summarized sufficient to place
bounds around the dose at which toxicity likely occurs. It was the collective results rather than any one
study that convinced me that an RfD was appropriate and verifiable. Of the available studies of Aroclor
1016, the series of prospective studies of rhesus monkeys best met the stated criteria for selection of a
"principal study" for RfD development. My brief review of the alternatives to these studies as
replacements, found the rat, mouse and mink studies to be less desirable. It is a judgement call whether
the rhesus monkey studies should be excluded because of QA/QC concerns.
The reasons to utilize these studies need to be more clearly detailed in the beginning of the IRIS
documentation. I found the rhesus studies certainly had "warts" but I did not feel they individually or
collectively had fatal flaws. Hypothetically, if these studies were excluded, the decision becomes whether
the remaining data base is sufficient to support the development of an RfD. I did not find any of the
remaining studies as convincing as the rhesus studies - even with their detracting elements. The use of
the NOAELs or LOAELs derived from the rat, mouse or mink studies present greater uncertainties in
extrapolation which would need to be accounted for, following the RfD development protocol, through
application of greater uncertainty factors. It would not be unreasonable to see a combined uncertainty
factor of 3,000-10,000 required with such studies. The resulting RfD would be similar or lower than
the proposed RfD based on the rhesus studies, and present lower confidence.
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Henry A. Anderson, M.D.
Because the rhesus studies have detracting factors which suggest caution in their use, it becomes
especially important for the IRIS material to highlight the consistency within the collective studies as well
as between Aroclors and perhaps discuss the range of possible RfDs from the various studies. The
arguments for why the rhesus monkey is the best species can be found in the document, but it takes some
hunting. It would help if the arguments supporting the selection of the "principal study" were clearly
stated in the beginning. While I support the committee conclusion, the justification and decision analysis
was spread out in the document and required some hunting. The descriptive study data is concisely
summarized, but the committee interpretation and judgement decision process is less well delineated.
It would be helpful if a separate paragraph or section would discuss the confounders in the
principal studies and the committee decision on the implications to the RfD process more clearly
summarized. Additional analyses were performed by the Agency. It should be explained why these were
done. The additional analyses (among the reasons appears to be to assess whether decreased gestation
length could explain the decreased body weights) need to be better explained and whether the analyses
resolved the committee questions. Thus strengthening the study findings and the resulting RfD.
Element 2: Selection of Critical Effects
I support decreased birth weight as an appropriate "critical effect" for the development of the
RfD. Decreased birth weight is a well recognized adverse event in animal toxicology. It is not usually
considered one of the more subtle toxicologic endpoints. While decreased birth weight is a non-specific
adverse effect indicator (compared to specific organ system evaluations such as neuro:behavior, hepatic
or immune system function), it has proven a useful animal predictor of potential human risk. Decreased
birth weight is also an important indicator of health status in humans. The mean birth weight of the 1
ppm group was 20% less than the controls and the 0.25 ppm group was decreased by 8% (but not
statistically significant). This supports a dose-response relationship. But does the 0.25 ppm group
represent a NOAEL? It is only a sample size issue that keeps the 8% decrease from being significant.
That 0.25ppm is a NOAEL for this endpoint is supported qualitatively by the 0.025 ppm group that was
deleted because of cross-contamination. Despite the contamination, the mean birth weights were the same
as the 0.25 ppm group. The impact on birth weight does seem to occur somewhere between the 0.25
ppm and 1.0 ppm dosage.
In any animal or human study the control group is critical to understanding the effect. An
alternative to a toxic effect could be that the control births were heavier than normal. If available, it
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Henry A. Anderson, M.D.
would be useful to see historic birth weights from this colony. No mention is made of whether the 1 ppm
group birth weights were significantly different from the 0.25 ppm study group. If significant, or very
close, this would support the interpretation of a toxic effect rather than an artifact possibly due to the
control monkeys being better acclimated to the colony, and more mature causing larger babies and the
significant group differences.
Greater detail of the re-analysis purpose and results would be helpful. While I think I understand,
being more explicit would help IRIS users and strengthen the decision to use these studies.
The discussion accurately reflects the complexity of understanding the pathologic mechanism and
interpreting neuro-behavior test results. These can be confusing to understand and difficult to interpret.
In any case, I would not interpret these data to provide strong support for a LOAEL at 0.25 ppm Aroclor
1016, the low-birth weight NOAEL.
My interpretation of these rhesus monkey studies is that the investigators did a good job of
choosing exposures that likely bracket the true NOAEL and provide greater detail of study design, dose
and identification of possible cqnfounders than most studies used to derive RfDs. At this point, I am not,
convinced that the study results are significantly impacted by the confounders.
Element 3: Selection of Uncertainty Factors
I can support a total uncertainty factor of 100 as being a reasonable choice. The assignment and
combination of individual uncertainty factors is a professional judgement. The fact that the choice was
a committee determination strengthens the consensus decision. Even with the best of studies and data
sets, uncertainty factors less than 100 are seldom used - except for when strong human data is available.
Thus, considering the characterized weaknesses in the studies and the lack of multiple studies in the same
species, a higher uncertainty factor - perhaps 300 could also be defended (3 for sensitive individuals, 3
for monkey to man, 3 or 10 for Aroclor 1016 specific data limitations, and 3 or 10 for sub-chronic to
chronic. My acceptance of the 100 (3,3,3,3) is based on the extensive data on all PCBs and the opinion
it is unlikely 1016 would provide any surprises if all the PCB studies had been done using 1016.
An additional reason for not considering the study a "chronic" study (supporting increasing the
uncertainty factor) is the observation that the body burden of Aroclor 1016 did not appear to have reached
steady-state at the time of conception (doubled between the 4 and 7th month of dosing) and went up at
parturition. Although the daily dose of Aroclor 1016 was steady, the tissue levels of PCB appear to have
been increasing over the course of the pregnancy. If body burden (tissue concentration) is a significant
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Henry A. Anderson, M.D.
contributor to the toxicity, then attributing the effect to the daily dose may underestimate the "chronic"
toxicity, if tissue levels have not equilibrated. This issue becomes even more important if the toxic effect
is the result of a narrow time period during the early rather than the late pregnancy stages,
Element 4: Weight of Evidence Conclusions
It would be helpful if a "critical issues" section were added. The summary in the "Charge to
Reviewers" does a nice job and a similar approach would be helpful hi this section. The purpose of this
section seems to be twofold. First to concisely summarize the remaining literature, and second, to point
out how those studies support specific decisions made hi constructing the RfD. Since perhaps the most
important information is the NOAEL, LOAEL reports from the studies, it might be useful to have a table
listing these. This would be more convenient than having to read all the summaries to get that
information.
I would move the portions that are justification for the critical study (such as the similarity of
human and monkey metabolism) into the first section. Similarly the discussion of placentatioh in the
"Confidence" section is further support of the study choice and would contribute to the initial section.
I think it would be helpful to include a discussion/description of the Aroclor 1016 tissue levels
described in the various studies. While traditional toxicologic descriptions of dose use the mg/kg/day
convention, the actual tissue-delivered-dose can provide additional useful information. As mentioned in
an earlier section, the issue of achieving equilibrium between dose and circulating/tissue PCB is worth
discussing. Does being on the steep slope of accumulation differ from being on a more gradual increase
as equilibrium is neared? These tissue data would be especially useful hi comparing the animal doses to
what is seen in humans.
Part H
My initial recommendation to RfD/RfC work group is Option B. After reviewing the IRIS assessment,
the background material sent to the reviewers and the Agency for Toxic Substances and Disease Registry
(ATSDR) toxicological profile for the PCBs, my initial impression is that the proposed Aroclor 1016 RfD
reasonably reflects the chronic toxicity of the compound. Since scientific research seldom (if ever)
provides a truly definitive data-set which uniformly meets every expectation, the differing scientific
approaches to addressing the realities of the Aroclor 1016 study deficiencies via the risk assessment
process will trigger debate. The background material indicates that the RfD/RfC work group was well
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Henry A. Anderson, M.D.
aware of the problematic aspects of the Aroclor 1016 data base. I found their evaluation approach
appropriate, if not always clearly enunciated and documented. The studies are well presented, but the
decision logic not always 'clear.
Of course, I may change my recommendation based upon the other reviewers comments and the
workshop deliberations. I look forward to a lively discussion.
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Douglas Arnold
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D.L Arnold
Premeeting Comments
A. Part I - Selection of Principal Study
The selection of Barsotti's study, wherein female monkeys were fed graded dosages
of Aroclor 1016 and their infants subsequently underwent behavioral testing, is the
appropriate principal study for the RfD Workshop's consideration based upon my
knowledge of the published studies dealing with Aroclor 1016. However, there are
several underlying concerns with the determination of the reference dose described in
Attachment 1 of the packet received from ERG that require comment.
1. In Part I. A.1. Oral RfD Summary, the matter of how much Aroclor 1016 was
consumed by the female monkeys is not clearlyievident.
a) "Conversion Factors: Dams received a total average intake of 4.52 mg/kg (0.25
ppm) or 18.41 mg/kg (1 ppm) throughout the 121.8 month (654 days) dosing
period".
In Barsotti and van Miller, Toxicology 30: 31-44 (1984):
p.33 "Daily food and Aroclor 1016 consumption was calculated by counting the
remaining (feed) pellets and subtracting from the quantity offered".
-)
p.35 "Feed Analysis: The results of the analysis of the 3 diets for Aroclor 1016
content were 0.700±0.130 (N=12), 0.164±0.031 (N=12) and 0.005±0.001 (N=9)
ppm in the 1.0 and 0.25 ppm Aroclor 1016 diets and control chow, respectively".
p.35 "...the calculated intake of Aroclor 1016 (based on 1.0 ppm PCB) was...".
Schantz et al Neurotoxicoloav and Teratology 11:243-250 (1989):
p.244 "For the PCB-exposed groups, the PCB intake of each animal was estimated
by multiplying the number of grams of food consumed by the PCB concentration in
the feed".
It would appear that the Aroclor 1016 consumption was determined solely by
counting the number of feed pellets given, determining how many were left, and
assuming all of the "missing" pellets were consumed. This is an extremely crude
manner in which to determine even qualitative consumption. There appears to be no
consideration given to a monkey's habit of lobbing its feed cubes out of its cage
and/or "losing" significant amounts of feed in the fecal pans beneath its cage. In
short, consumption of Aroclor 1016 may have been overestimated by 1-20%.
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D.L. Arnold
Secondly, Barsotti's and van Miller's analysis of the 1 ppm and 0.025 ppm Aroclor
1016 diets was found to be 30% and 34%, respectively, short of the desired
concentration.
In summary, Aroclor 1016 consumption appears to have been overestimated,
firstly, because the "missing" feed cubes were assumed to have been consumed
and, secondly, because the diets do not appear to contain the amount of Aroclor
1016 required by the protocol. Neither of these shortcomings appears to have been
addressed when the Conversion Factors were calculated.
*
b) Further to this point, from Barsotti's thesis:
p. 188 'The total intake of Aroclor 1016 by the adult females at the time the infants
were weaned was 19.1 ± 4.4 mg/kg for the 1.0 ppm group, 4.6 ± 0.6 mg/kg for the
0.25 ppm group and 0.5 ±0.1 mg/kg for the 0.025 ppm group (Table 6-2)".
p.208, Table 6-2.
Intake of Aroclor 1016 by Adult
Female Rhesus Monkeys
Level of 1016 in diet
Intake at Weaning
(mg/kg)
1
0.25
0.025
18.1±3.1
4.5±0.6
0.5±0.1
There is an obvious discrepancy between the text values and the Table values.
c) In addition to the discrepancy noted above, Schantz et al (1989), adds further
confusion to this matter.
p.247 "Cumulative PCB intake by the 0.25 ppm and 1.0 ppm mothers averaged 4.52
± 0.56 mg/kg or 7.58 ± 0.28 ug/kg/day and 18.41 ± 3.64 mg/kg or 29.7 ± 2.3
ug/kg/day, respectively11.
Regardless of the obvious discrepancies in Aroclor 1016 consumption values
between Barsotti's thesis and Schantz et al (1989), the calculation of Aroclor 1016
consumption data to 1/100 of a mg is totally inappropriate given the rather crude
manner in which feed consumption was determined/calculated.
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D.L. Arnold
2. Some comments pertaining to Part I. A. 2. Principal and Supporting Studies (Oral
RfD).
a) 1st para., 3rd line:
"Aroclor 1016" is a commercial mixture of polychlorinated biphenyls (PCBs) devoid
of chlorinated dibenzofurans (Barsotti and van Miller, 1984)".
Barsotti and van Miller, 1984 p.33:
"...as was previously reported for American PCBs, (Aroclor 1016) was found to be
devoid of chlorinated dibenzofurans [19, J. McKinney personal comm.]".
In the RfD quote, it appears that the Agency has accepted the contention of
Barsotti and van Miller that Aroclor 1016, and by implication, the Aroclor 1016 used
by Barsotti, does not contain any chlorinated dibenzofurans (CDF). However, the
quote from Barsotti and van Miller (1984) is ambiguous. Reference 19 is an article
authored by Bowes et al (Nature 256:305-307, 1975) in which Bowes et al did not
detect any CDF congeners with 4, 5 or 6 chlorine atoms in the one sample of Aroclor
1016 they analyzed, but Bowes et al did report finding CDF in the other commercial
PCBs they tested even though Bowes et al cited previous reports that had not always
detected CDF in similar commercial PCB mixtures. Consequently, it appears there
was some controversy regarding the presence or absence of CDF in various
commercial PCB mixtures when these reports were first published.
The intent of the personal communication from J. McKinney is unclear.
Barsotti's thesis adds further confusion to the issue of whether CDFs were
present in the lot of Aroclor 1016 she used:
"Three of the groups were placed on the diets containing 1.0, 0.25 and 0.025 ppm
Aroclor 1016 (<5 ppb dibenzofurans, McKinney, personal communication)."
(p.183)
Appendix V of Barsotti's thesis, entitled PCB Analysis, does not indicate that the
Aroclor 1016 used in her study was ever analyzed for contaminants. Appendix V
only describes the analytical techniques employed in the analysis of the feed,
monkey tissues and the breast milk for PCBs. (Barsotti's thesis, Appendix V, pp.231-
236.)
In summary, there is no substantive indication either in the Barsotti and van Miller
paper or in Barsotti's thesis that the Aroclor 1016 used by Barsotti was ever analyzed
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D.L. Arnold
for contaminants, and as a consequence, there appears to be no basis in fact for the
contention in the RfD that the Aroclor 1016 used by Barsotti was devoid of CDF.
(Might it be useful to have Dr. Barsotti present at the Workshop so that this and
other issues which may be raised could be answered authoritatively?)
b) 1st para., line 5:
"Analysis of the commercial feed used for this study revealed contamination with
congeners specific for Aroclor 1248, present in the parts per billion range".
Barsotti's thesis p. 192:
'The finding of higher chlorinated PCBs in control and experimental samples is
not surprising since PCBs have been shown to be ubiquitous in the environment.
They have been found in commercial monkey chow also (Coleman and Tardiff,
1979). We have shown that the concentration of PCBs in control monkey show
(sic) is in the range of 1-50 ppb on the basis of an Aroclor 1248 standard".
The RfD statement clearly states that the monkey chow was contaminated with
Aroclor 1248. However, the support for such a statement is unclear.
Barsotti's thesis suggests that the higher chlorinated chromatographic peaks
found when she analyzed her diets for PCBs was associated with the Aroclor mixture
1248, but the higher chlorinated peaks were found in both the control and test diets.
Both the RfD statement and Barsotti's thesis indicate that the levels of the purported
Aroclor 1248 peaks were in the ppb range without further elaboration. However, one
is unable to ascertain from either Barsotti's thesis or the RfD as to when the feed
may have been contaminated; that is, prior to receipt from the manufacturer or during
the pelleting operation.
The analytical methodology used by Coleman and Tardiff as well as the Barsotti
analytic methodology (Appendix V) appear to be the same AOAC (Association of
Official Analytical Chemists) method. Coleman and Tardiff reported detecting PCBs
in 11 of the 12 fed samples they analyzed, but the levels of contamination were less
than 10 ppb, having previously indicated their limit of detection for PCBs was 10 ppb.
However, Coleman and Tardiff do not comment as to whether the PCBs they
detected may have originated from higher or lower chlorinated PCBs congeners.
Consequently, what information does the Agency have in support of its contention
that Barsotti's test diets were contaminated with Aroclor 1248 after the feed left
Purina's facilities; that is, the contamination occurred during the pelleting process?
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D.L. Arnold
As previously indicated (A.1.a), Barsotti and van Miller reported that they analyzed
their test diets on 12 different occasions and the control diet on 9 different occasions.
Consequently, if Barsotti's diets had been contaminated during the pelleting process
with Aroclor 1248, some analytical data should be available to indicate whether the
contamination did occur during the pelleting process as well as indicating the
duration of the purported contamination. Will the analytical data for Barsotti's diets
be made available to the workshop participants?
c) 1st para., line 14:
"No exposure-related effects on maternal food intake...".
Barsotti's thesis:
p. 182 During the monkeys quarantine period the monkeys were "given food and
water ad libitum...".
p. 186 "Prior to breeding there were no changes in food intake...".
p.188 'The animals maintained normal food consumption and body weight..."
referring to the adult females.
Barsotti and van Miller (1984):
p.33 "All animals were offered 200 g of chow/day".
The amount of feed offered to the monkeys during the experimental period is
ambiguous based solely on the comments in Barsotti's thesis. One might assume ad
libitum feeding could easily have been used in view of the manner in which feed
consumption was calculated (item A.1.a). However, the Barsotti and van Miller
(1984) manuscript states that the monkeys were restricted to 200 gms of feed per
day. The troubling aspect of this is that the additional caloric requirements of .
gestation and lactation may not have been met by the 200 gm daily portion of feed. If
the caloric requirements were not met by the 200 gms of feed per day, what effect, if
any, might this have upon the infant's birthweight? If there was any effect upon
birthweight, might one expect the effect to be dose-related? In view of a possible
dietary restriction, might the infant birth weight differences be analagous to the
wasting syndrome reported for some halogenated hydrocarbons?
d) 1st para., line 14-16:
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D.L. Arnold
"No exposure-related effects on maternal food intake, general appearance,
hematology, serum chemistry (SGPT, lipid, and cholesterol analysis) or number of
breedings were observed (Barsotti and van Miller, 1984). All monkeys had
uncomplicated pregnancies, carried their infants to term and delivered viable
offspring".
Barsotti and van Miller (1984):
p.36 "...there were no changes in (maternal) food intake or general appearance of
the experimental animals. No significant differences were found in any
hematological or serum chemistry values between the 3 groups.
p.36 "After 2.2 ± 0.8,2.5 ±1.3 and 1.2 ± 0.4 breeding attempts, all of the females
conceived in the 1.0 and 0.25 ppm Aroclor groups and controls, respectively".
Barsotti's thesis p. 186:
"Prior to breeding there were no changes in the food intake, general appearance,
hemograms, or serum chemistries. In addition the menstrual cycles of the
animals were unmodified as a result of the PCB exposure (Chapter 2). The levels
of the circulatory serum estradiol and progesterone during the third and sixth
month of the experiment were determined to be similar to those recorded prior to
the administration of the diets containing PCBs".
Some (J.A. Moore (1993) IEHR PCBs and Primate Reproduction Meeting August
30-31,1993; IEHR, Suite 608, 1101 Vermont Avenue, N.W., Washington, D.C.,
2005) have suggested that the birth weight reduction observed when PCBs were fed
to rhesus monkeys were secondary to maternal toxicity. However, the above
statements from Barsotti and van Miller (1984) and Barsotti's thesis clearly indicate
that there was no apparent maternal toxicity evident. Consequently,-maternal toxicity
was not necessary for the marked dose-related decrease in infant birthweight.
However, one might muse that the approximate two-fold increase in breeding
attempts to attain 100% impregnation in the Aroclor 1016 groups - while not
statistically significantly different from the control group, possibly due to the small
number of monkeys used in each test group - might be biologically significant and
consequently, a suggestive indication of possible maternal toxicity.
e) 1st para., lines 22-34 re:
Statistical analysis of the infant birthweights
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D.L. Arnold
Birthweight vs. gestation length
Birthweight vs. sex of the infants
Birthweight vs. paternal exposure to Aroclor 1248
In view of the amount of birthweight reanalysis done by the Agency, one must ask
why no reanalysis was done regarding the distribution of shared paternity described
by Schantz et al., 1989; Table 2.
f) 1st para., lines 28-29:
"Males that had sired some infants were exposed to Aroclor 1248...".
Schantz et al, 1989, p.247:
"Beginning in the seventh month of exposure, seven of the females in each group
were bred to unexposed males".
Schantz et al. Environmental Toxicology and Chemistry 10:747-756 (1991), p.749:
'The mothers of both PCB-exposed and control subjects were bred with
unexposed male breeders".
Levin et al. Archives of Toxicology 62:267-273 (1988), p.269:
"Seven of the females in each group were bred to unexposed males".
What is the Agency's basis for concluding that some of the sires for the Aroclor
1016 females were, in fact, exposed to Aroclor 1248?
g) 1st para., lines 39-40
"Hyperpigmentation was present at birth in the low- and high-dose infants but did
not persist once dosing was stopped".
This sentence suggests that the infants were actually dosed. The only exposure
to PCBs that the infants received was in utero. via lactation and whatever amount of
their dam's diet they may have ingested. Therefore, it might be more correctly
indicated that hyperpigmentation did not persist once the infants were weaned and/or
placed in their own cage.
h) 1st para., lines 41-42:
'The concentration of Aroclor 1016 in breastmilk was higher than the maternal
dose".
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D.L Arnold
This statement might be clarified to indicate whether the comparison is on a wet
weight or lipid basis.
3. Comments concerning Part I.A.3. Uncertainty and Modifying Factors
a) Line 6 "...because of similarities in toxic responses and metabolism of PCBs...".
Is the data base sufficient that such an assumption is justified, or is it a case of
the limited data available indicating that humans and monkeys may metabolize PCBs
similarly? The last paragraph of Section I.A.4. and the May 25,1990, memorandum
of Dr. Mike Dourson both indicate that the metabolism of two PCB congeners is
similar in monkeys and humans. In my opinion, this is not sufficient evidence to
conclude that humans and monkeys metabolize PCBs similarly.
b) Line 8-9:
"In addition, the rhesus monkey data are predictive of other changes noted in
human studies such as chloracne,...".
Chloracne is far from a universal finding when PCBs are fed to monkeys, as per
the following references:
Yoshihara et al (1979) Fukuoka Acta Medica 70:135-171 :
Male and female rhesus monkeys were fed daily dosages of 0.25 or 0.5 mg KC-
400/kg/day.
p.10 "...acneform eruptions, for instance - were not always evident".
Truelove et al (1982) Archives of Environmental Contamination and Toxicology
11:583-588:
Aroclor 1254 was fed to pregnant cynomolgous monkeys for approximately 60
days during gestation and for a total of 178 to 207 days after parturition at levels
of 100 and 400 ug/kg bw/day.
No chloracne was observed.
Tryphonas et al (1984). Toxicology Pathology 12:10-25:
Aroclors 1248 and 1254 were fed 3 days per week at levels of 4.7 and 11.7 mg/kg
bw, respectively to female cynomolgous monkeys for 29-164 days. Death or
morbidity generally determined the length of dosing.
No chloracne was reported.
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D.L. Arnold
Tryphonas et al (1986). Toxicologic Pathology 14:1-10:
Aroclor 1254 was fed to female rhesus monkeys for 5 days/week at a level of 200
pg/kg bw/day for 27-28 months.
No chloracne was reported.
Tryphonas et al (1986) Archives of Environmental Contaminantion and Toxicology
15:159-169:
Aroclor 1254 was fed to female cynomolgous monkeys for 5 days/week at a level
of 200 |jg/kg bw/day for 12-13 months.
No chloracne was reported.
Arnold et al (1990) Food and Chemical Toxicology 28:847-857:
Aroclor 1254 was fed to female cynomolgous (55 weeks) and rhesus (120 weeks)
monkeys at a level of 280 ug Aroclor 1254/kg bw/day.
No chloracne was reported.
Arnold et al (1993) Food and Chemical Toxicology 31:799-810:
Aroclor 1254 was fed to female rhesus monkeys at levels of 5, 20,40, or 80 ug/kg
bw/day for more than 3 years.
No chloracne was reported.
c) Line 14:
"As the study duration was considered as somewhat greater than subchronic...".
This appears to be a rather unfortunate phraseology; that is, how can the duration
of dosing be somewhat greater than subchronic but less than chronic when the only
three choices are acute, subchronic and chronic? Might the author be trying to
indicate that the dosing duration for this monkey study greatly exceeded the minimum
requirements for a subchronic study with this species but was not sufficient for a
chronic study?
4. Comments concerning Part l.A.5. Confidence in the Oral RfD.
a) Para. 1, line 2: *
"The initial study was well conducted...".
While the benchmark for a well-conducted study could be an invitation to an open-
ended discussion, it is obvious that the level of conduct for this study would have
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D.L. Arnold
been much improved if the diets had been analyzed prior to their being fed, and
contaminated diets discarded.
b) Para. 1, lines 9-11:
"Although contamination of the control laboratory primate diet...".
See A.2.b regarding the substantiation of the contention as to when and/or if the
primate diets were contaminated with Aroclor 1248.
The apparent contamination of the diets with another halogenated compound as
well as conceivably with nonAroclor 1016 congeners, without information concerning
the apparent duration of the contamination, makes the evaluation/extrapolation of
these data more difficult. However, the lack of hyperpigmentation in Barsotti's
control infants does indicate that the purported nonAroclor 1016 congeners present
in the diet were of very minimal, if any, lexicological significance.
B. Selection of Critical Effects
The reduction in birthweight of the treated dams' infants, in a dose-related manner, is
the most significant toxicological effect observed. This finding takes on added
significance in view of the fact that it occurred without any apparent maternal toxicity (see
A.2.d). However, as pointed out above (A.2.d), it is tempting to speculate as to whether
the increased number of matings in the treated groups required to attain 100%
impregnation is biologically and toxicologically noteworthy.
C. Selection of Uncertainty Factor
As pointed out in A.4.a, one could argue as to what may constitute a '"well
conducted' subchronic study that only defines a LOAEL". If there was consensus by the
Workshop members that this study was something less than "well conducted", then
consideration of a larger uncertainty factor would be appropriate. However, the
seemingly predetermined use of the factors 1, 3 or 10 may truncate such a discussion.
The UFS= 3 may be in need of some revision, if a major consideration for its selection
was that "the mothers were probably dosed to 'steady state'". There are very few studies
in the published literature that provide any direct insight into this consideration; however,
the following studies do provide some information for consideration.
1. Barsotti, et al (1976) Food and Cosmetic Toxicology 14:99-103, p.100:
'The data obtained from the fat biopsies on the female animals (fed Aroclor 1248
at dietary levels of 2.5 or 5.0 ppm) showed an accumulation of PCB isomers in the
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D.L. Arnold
adipose tissue. After a 6 month exposure period, the PCB level in the adipose
tissue of the animals receiving 5 ppm attained a plateau, subsequent values
varying little with continued consumption of the diet. A similar level was attained
in 1 yr by the group given 2.5 ppm PCB".
2. Yoshimura et al. (1981) Fukuoko Acta Medica 72:156-184, p.162:
'The fact that the blood PCB concentration gradually rose when KC-400 was
given (at dietary levels of 0.25 and 0.5 mg/kg) to rhesus and cynomolgous
monkeys is the same as in the case of the preliminary study, and in the first
administration experiment it reached a maximum at around five months after the
commencement of administration".
While one might construe this statement to suggest a qualitative pharmacokinetic
steady state approximating 5 months, subsequent work has demonstrated that the
level of PCBs in blood is often related to its lipid content; therefore, blood is not the
most appropriate specimen for obtaining data regarding steady state PCB
determinations.
3. Arnold et al. (1993) Food and Chemical Toxicology 31:799-810, p.800:
"...it required approximately 25 months to attain a satisfactory qualitative steady
state for 90% of the (Aroclor 1254) treated monkeys (rhesus)". (Dose levels were
5, 20, 40, or 80 pg/kg bw/day.)
D. Weight of Evidence Conclusions
1. Primary Evidence Used for the RfD, iteml:
'The NHP provides conclusive data...".
The use of the word conclusive seems inappropriate since the second sentence in
the introduction of the RfD states "The summaries presented in Sections I and II
represent a consensus..."; suggesting a lack of complete harmony amongst the
Agency's reviewers.
2. Secondary Evidence, item 2:
"Chloracne and pigmentation have been observed in both NHP and humans".
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D.L. Arnold
Has chloracne been reported when monkeys were exposed to Aroclor 1016? The
production of chloracne when monkeys were fed Aroclors was not consistently
observed as previously mentioned (A.3.b).
3. Secondary Evidence, item 4:
"]n vitro metabolism of several PCB congeners is similar for NHP and humans".
Several is defined by Webster's Ninth New Collegiate Dictionary as "more than
two but fewer than many".
Section.I.A.4, last para., of the RfD - "Data exist on the ]n vitro hepatic metabolism
and |n vivo metabolic clearance of 2, 2', 3, 3', 6, 6' - hexachlorobiphenyl and 4, 4' -
dichlorobiphenyl congeners in humans, monkeys, dogs, and rats (Schnellman et al.,
1985). Both of these congeners are present in Aroclor 1016, but hexachlorobiphenyl
is only a minor constituent". Since two congeners does not constitute several
congeners, was some data inadvertently left out of the RfD summary?
E. Part II. Recommendations
My preceding comments indicate that I do have some difficulty with the current text
regarding the analysis/evaluation of the Barsotti - Aroclor 1016 monkey study data. It is
my opinion that the limitations regarding the data have not been adequately elaborated.
In addition, I also have some concerns about the uncertainty factors. Consequently, if I
have to choose an option based on the information provided in the package I received
from ERG, I would choose Option C. However, if appropriate information is available at
the Workshop, I would be prepared to switch to Option B.
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Thomas Burbacher
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EPA TECHNICAL WORKSHOP ON THE REFERENCE DOSE
FOR AROCLOR 1016-PREMEETING COMMENTS.
Thomas M. Burbacher
Comments on the selection and use of the four reports listed in attachment 1 as
the primary basis for the RFD for Aroclor 1016.
The 4 reports used as the primary basis for the RFD for Aroclor 1016 come
from essentially 1 longitudinal study of the reproductive and offspring
developmental effects of prenatal and early postnatal Aroclor exposure in
nonhuman primates. Three of the reports describe procedures to assess the
learning and memory abilities of Aroclor and nonAroclor exposed monkeys or
"controls". While these reports describe adequate experimental procedures to
test learning and memory in nonhuman primates, the scientific reliability of
these reports (and the first report) rest largely on decisions made during the
initial phase of this longitudinal study. For it is these early decisions that
determine the validity of making comparisons across the Aroclor exposed groups
and the "control" group.
The information supplied to me to date is too sketchy to evaluate whether
the scientific reliability of these reports is of sufficient quality to be used as the
primary basis for the RFD for Aroclor 1016.1 do, however, have serious
reservations about the quality of the initial phase of the study based on the
information provided. I will go into a little detail regarding the basis for my
reservations but I would like to mainly provide a series of questions that I
believe must be answered before a full evaluation of these reports can be made.
It is possible that all of these questions have been answered sufficiently during
previous deliberations of this issue. If this is the case, it should not be too much
trouble to supply these answers to the panel for this technical review.
> When designing a nonhuman primate study to assess the reproductive and
offspring developmental effects of a compound, one of the first orders of business
is carefully choosing your adult subjects. Ideally, the adult animals that are
chosen are of known age and parity, are healthy as determined by past medical
records and weights and have a history of no previous invasive-studies. Females
and males can then be assigned to different exposure and control groups to
counterbalance these factors across groups. As anyone who has been involved in
nonhuman primate studies knows, however, the ideal situation rarely occurs.
When this happens, it is up to the investigator to do the best he or she can to
provide groups of adults balanced on as many potentially confounding factors as
possible. My first series of questions relates to the characteristics of the adult
monkeys at the beginning of the study (when Aroclor exposure began).
-What were the estimated ages of the adult animals in the different groups?
-What were the weights of the adult animals in the different groups?
-What were the colony parities of the 8 females from the general colony who
served as controls? I am assuming that the colony parities of the Aroclor
exposed monkeys was 0.
-What was the reproductive history of the males used in the study?
-Were any of the adult animals used in previous invasive studies?
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EPA TECHNICAL WORKSHOP ON THE REFERENCE DOSE
FOR AROCLOR 1016-PREMEETING COMMENTS.
Thomas M. Burbacher
Comments on the selection and use of the four reports listed in attachment 1 as
the primary basis for the RFD for Aro'clor 1016 (continued).
Another important design consideration for these studies relates to the
procedures that are used on adult animals during the entire investigation
(including the baseline period). My second series of questions relates to the
procedures that were used on adult females prior to and during Aroclor
exposure.
-Were the same procedures used on all adult females during the period just prior
to initiating the Aroclor and control diets (was there a baseline period)?
-If so, how long was this period and what procedures were used?
-Were the same procedures used on all adult females during the remainder of the
'study?
-If not, what procedures were differentially used and how?
-Were procedures used to collect data on the daily intake of the Aroclor and
control diets?
-If so, are data available concerning the intake of Aroclor during different stages
of the study (e.g.., prepregnancy, pregnancy, etc.)?
-Were procedures used to collect data on the weights of adult females during the
study
-If so, are data available concerning the weights of females during different
stages of the study (e.g.., conception, delivery, etc.)?
There are several other aspects of the initial phase of the study that are not clear
from the information provided. The above questions deal with the most
important aspects and should be considered a priority for the technical review.
The results of the other studies described in attachment 1 provide little
relevant information regarding the association between Aroclor 1016 exposure
and decreased birth weight or learning and memory deficits. The studies in mink
used an exposure level (2ppm) that showed no effects or a level (20ppm) that was
associated with frank maternal and infant toxicity. Reduced weights at this level
provide little information regarding possible effects at subtoxic exposures. While
the results of the studies of humans exposed to PCB do indicate a birth weight
and memory effect, these results cannot be associated directly with Aroclor 1016.
In summary, the information provided thus far indicates that previous ,
reviews of the principal study have concluded that they are of sufficient scientific
quality to be used as a basis for the RDF for Aroclor 1016.1 would assume that
the questions listed above have been answered to the satisfaction of the
reviewers during these previous reviews. If this is the case, it should not be too
much trouble to get the information needed to respond to these questions for the
current technical review.
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EPA TECHNICAL WORKSHOP ON THE REFERENCE DOSE
FOR AROCLOR 1016-PREMEETING COMMENTS.
Thomas M. Burbacher
Comments on the selection of low birth weight as the critical effect for the
Aroclor 1016 RFD, along with information on postnatal neurobehavioral effects-
Birth weight in nonhuman (and human) primates is associated with many
maternal, paternal and environmental factors. Well designed studies of
reproductive outcome and offspring development attempt to control the possible
confounding effects due to these factors in the design of the study or test for
these effects in the analysis of the data. For the principal study, the potential
effects of maternal age, parity, and weight on decreased birth weight should be
considered. Maternal weight gain during pregnancy should be examined for it's
possible contribution to decreased birth weight and paternal age and weight
effects should be considered. (See comments to first issue for more detail).
The learning effects observed in the Aroclor 1016 offspring at 1.5 years of
age are likely to be influenced less by the factors described above than is
decreased birth weight. The increase in the number of trials to learn a simple
spatial discrimination task in the high dose Aroclor 1016 group may be
important evidence of a learning deficit caused by Aroclor exposure. This was the
first task in a series of 4 tests for these monkeys. No effects were observed for
the subsequent 2 tests and the same group of monkeys performed better than
controls on the last test, a color discrimination reversal task, although no details
were provided regarding where the effects were observed (on original learning or
reversals). Finally, the performance of the Aroclor 1016 infants on a spatial task
at 4 to 6 years of age was not different than controls. The learning deficit of this
Aroclor 1016 monkeys was, therefore, very specific. Further studies in the area
of possible learning deficits associated with Aroclor 1016 exposure are needed to
clarify this issue.
In summary, decreased birth weight can be caused by many potentially
confounding factors that have to be considered in studies of nonhuman (and
human) primates. It is impossible to tell whether these factors were considered
in the principal study until more data are reviewed (see comments to first issue).
The data presented relating to the learning deficit on the spatial discrimination
task may provide a better endpoint for the critical effect for Aroclor 1016. Given
the specificity of the effect, however, more studies should be pursued prior to any
regulatory actions.
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EPA TECHNICAL WORKSHOP ON THE REFERENCE DOSE
FOR AROCLOR 1016-PREMEETING COMMENTS.
Thomas M. Burbacher
Comments on the weight of evidence analysis.
The weight of evidence analysis indicates that "the nonhuman primate
study provides conclusive data that the reduced birth weight of infants and
neurobehavioral effects is consistent with effects observed in other species
including the human". The results of studies on mink are used as supportive for
the reduced birth weight effect, while studies in rodents are used as supportive
evidence for the neurobehavioral effects.
As mentioned earlier, the mink studies used an exposure level (2ppm) that
showed no effects or a level (20ppm) that was associated with frank maternal
and infant toxicity. Reduced weights at this level provide little information
regarding possible effects at subtoxic exposures. The reference to results from
rodent studies as supportive for the neurobehavioral effects could not be
confirmed with the information provided.
The weight of evidence analysis also indicates that "methodological
considerations precluded using the neurobehavioral effects and transient dermal
pigmentation as co-critical. It is not obvious why methodological considerations
preclude these effects and not the decreased birth weight effect.
Some of the secondary evidence listed provides support for the effects
reported in the in primary study. The studies of changes in dopamine may be
associated with the learning deficit observed, although effects observed in adult
animals may not be particularly relevant to developmental exposure. The
chloracne and pigmentation observed in nonhuman and human primates seems
similar. The similarity in iiivitro metabolism of PCB congeners supports the use
of nonhuman primates as an animal model. The decreased birth weight-effects in
•mjn'k- are most likely not very relevant due to the doses used.
In summary, it is noted in attachment 1 that the data base available for
PCBs is extensive. This may be the case when this data base is compared to most
other compounds. However, until the reliability of the primary study is
confirmed and additional supportive studies using relevant doses and procedures
are performed, I would judge the weight of evidence for the RFD for Aroclor 1016
as weak.
RECOMMENDATIONS
Based on the current information, my preferred option would be C, Revise
the Aroclor 1016 RFD value and accompanying analysis in line with peer review
recommendations. This recommendation is preferred because more detail of the
limitations and associated analysis of the critical study are needed to provide a
convincing argument for using the study. The descriptions of supportive studies
in the analysis should also include more discussion regarding the limitations of
the studies. Finally, this section should also be updated with relevant data
published after 1992..
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Peter deFur
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Peter L. deFur
Selection of Principal Study
The principal study, dissertation research conducted by Dr.
Barsotti, and subsequently published in a series of papers in
peer-reviewed literature, is appropriate for setting the Rfd for
Arochlor 1016. The experimental design, confirmation of
administered doses, range of doses, choice of measurement end
points and follow-up for as much as four years are strengths of
the research. The results of the research from this experiment
are consistent with results of related work on other species,
although there have been no published corroborations in rhesus
monkeys. Factors in the original study, cited in the
accompanying materials, leading to questions regarding use of
Barsotti and Van Miller et seq., for setting the Rfd, are not
sufficient to discount this study.
Selection of Critical Effects
The choice of low birth weight as the critical effect for setting
an Rfd is appropriate at this time. The advantages of low birth
weight are the comparability to human effects, the power of this
measure as a predictor of later adverse effects and the apparent
sensitivity of the fetus. This latter is consistent with recent
published research on the fetal sensitivity of rats to a chemical
(2,3,7,8 TCDD) believed to act through a mode of action common to
the PCB's (Mably et al., 1992).
Selection of Uncertainty Factors
The uncertainty factor analysis for Arochlor 1016 is consistent
with guidelines and practices used by the Agency. Using an
uncertainty less than 10, based on the similarities between the
experimental animals and humans, confirmatory results in other
species and consistency with other results are appropriate
choices for the Agency.
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Peter L. deFur
The selection of four categories of uncertainty and exclusion of
the fifth category, NOAEL to LOAEL extrapolation, is based on the
non-significance of the somewhat reduced birth weight of the
experimental group at what was subsequently determined as LOAEL.
The Agency may wish to consider further examination of this
LOAEL. Considering that the low dose group had a reduced birth
weight, albeit not statistically significant, delayed
neurobiological and chronic health effects should be evaluated.
Weight of Evidence Conclusions
The primary and secondary evidence support this Rfd for Arochlor
1016. The results are conclusive and consistent both within the
study by Barsotti and Van Miller and the research on other
species. The difficulty in assessing human responses to known
exposure conditions does not weaken the conclusions based on the
experimental results.
Recommendation
Confirm the Arochlor Rfd value as in the IRIS entry, with any
text modifications resulting from this review.
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Mari Golub
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Man S. Golub, Ph.D.
COMMENTS FOR TECHNICAL REVIEW WORKSHOP ON AROCLOR1016 RfD
INTRODUCTION
After reviewing the materials provided, it is my opinion that the issue that requires most
attention from scientific reviewers is selection of endpoint.
Two issues that would profit from clarification based on more information are: the RfD
workgroup birthweight analysis; and the rationale for selection of some uncertainty factors.
Diet contamination does not appear to be a major issue from a scientific point of view since
internal dose measures are available and the experimental design is not confounded.
PARTI. COMMENTS
Selection of principal study .
1) Identification of the database:
There are a limited number of studies using Aroclor 1016 dosing. Although the
database for PCB1 mixtures with similar chlorine content is more extensive, there is no
indication that chlorine content is an important determinant of noncancer toxicity. In
addition for some commercial PCB mixtures with similar chlorine content (Kanechlor
300, Fenclor 42) contamination with PCDF2 and TCDD3 may be an issue. Since the
RfD is for Aroclor 1016, these studies are not strictly relevant and it seems appropriate
to limit the selection of studies to those using Aroclor 1016 dosing.
1 polychlorinated biphenyls
2 polychlorinated dibenzofurans
3 2,3,7,8-tetrachloro-dibenzo-dioxin
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Man S. Gdlub, Ph.D.
I am somewhat confused by the statement that the four published reports (designated as
the "principal studies") were drawn from the Barsotti doctoral dissertation, since Dr.
Barsotti is no included as an author. Perhaps it is meant that the four reports are based
on the same groups of animals that were dosed in connection with the Barsotti thesis.
The principal studies used the lowest dosing range; by exclusion they provide the
lowest LOAEL/NOAEL. The fact that sensitive endpoints were used in the principal
studies prevents any apparent inconsistency with LOAELs and NOAELs from other
studies. In particular the mink studies, which also use reproductive endpoints, showed
more severe effects at the higher dose range. Similarly, working backward from tissue
analysis data, Tilson et al.4 calculated that RfDs for developmental exposure to
environmental PCBs derived from human studies would be somewhat lower (.002-.07
ug/kg/day) than the Aroclor 1016 RfD derived here from nonhuman primate studies.
2) Quality of study:
Several basic and important features identify this as a good developmental toxicity
study: (1) chemical analysis of administered material; (2) measures of internal dose;
(3) route of exposure relevant to humans; (4) dose response design; (5) good level of.
detail In presentation (means, variance and n are presented for all measures); (6)
adequate determination of maternal toxicity; (7) statistical group differences with
appropriate analysis; (8) publication in peer reviewed journals.
The study did not contain a maternally toxic dose; the Barsotti thesis chapter states that
food intake, hematology, clinical chemistry and appearance were not affected hi the
treated dams. It would be helpful to know how the doses were selected for the study
and whether information on the maternally toxic dose was available. However, this is
not an important consideration since the purpose of the maternally toxic dose is to
preclude false negative findings based on use of an inappropriately low dose range.
Since the study did identify an effect, the dose range was de facto appropriate.
4 Tilson HA, Jacobson JL, Rogan WJ. Polychlorinated biphenyls and the developing nervous system: cross-species
comparisons. Neurotoxicology and Teratoloy 1990:12;239-248.
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Mari S. Golub, Ph.D.
A similar point applies to group size. The group size should be selected to provide for
sufficient power to detect group differences in the endpoint of concern. Since group
differences were detected, the group sizes were de facto large enough. Lack of
confidence in small groups is not appropriately based on statistical considerations;
statistical tests are adjusted for group size. However, evidence for balance in
background variables between groups is important when groups are small, and more
information on this would be valuable. The description of differences hi tune in the
laboratory is potentially relevant to balance in background factors. However, I am not
aware of any information indicating mat this factor influences birthweight.
Details are not available in the provided materials to evaluate all the challenges
presented in item 3 under Selection of Principal Study. However, the charge to
reviewers states that the RfD workgroup has considered these issues and they should be
able to respond to requests for information at the workshop. My comments are based
on the material available and my experience.
The issue of contamination is not clear to me. The control diet was apparently
contaminated with small amounts of both Aroclor 1016 and 1248. Whether the source
of contamination was in manufacture or processing in the lab is not known. Since this
exposure was common to all groups it would not have biased group comparisons.
There were undoubtedly other low level contaminant exposures from drinking water,
cage materials etc. as well as from the diet.
No specifics were mentioned concerning lack of conformity with GLP standards. At
the tune the study was designed, published GLP guidelines would not have been
available. However, formal GLP standards were derived from existing practices which
should be sufficient to judge the quality of the study.
Selection of critical effect
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Man S. Golub, Ph.D.
The three effects noted hi the principal studies are reduced birthweight, altered discrimination
learning and hyperpigmentation. The reason for not using the discrimination learning and
hyperpigmentation endpoints is briefly described as "methodological" (page 5 of Charge to
Reviewers).
Both low birthweight and altered discrimination learning occurred at the .028 mg/kg/day dose
level. It would seem that both these effects should be mentioned ("co-critical").
The documents mention several reasons why the "behavioral" measures were not used. Page 6
of Charge to Reviewers states that "the behavioral effects were not chosen as critical given the
biphasic nature of the response and the lack of statistical power in measuring differences to
control". This comment seems to apply to the delayed spatial alternation but not the
discrimination reversal tasks. The report of the June 1992 workgroup states that Dr. (Robert)
McPhail of HERL evaluated the studies and concluded that the neurological effects observed in
the Aroclor 1016 treated monkeys did not differ from the controls. However, no rationale for
this conclusion is provided.
A possible factor arguing against use of the discrimination learning effect is the fact that spatial
discrimination was unpaired while visual discrimination was enhanced. The authors of the
Schantz et al. 1989 article provide a convincing biological plausibility argument for the pattern
of effects seen in the discrimination reversal tasks. While both tasks involve discrimination,
the brain systems involving spatial and visual information processing are clearly distinct.
Other behavioral tasks do not assess these same functions. Facilitation of performance of some
tasks has been noted in other developmental toxicity syndromes such as those produced by lead
and mercury in nonhuman primates as well as in brain lesion syndromes as cited the authors.
Abnormalities of most specific endpoints can occur in either direction from the norm. An
exception is a global performance measure like IQ or school performance. Testing protocols
for nonhuman primates do not include such global measures of behavioral competence but are
geared toward specific functions.
Very limited rationale is given for exclusion of the hyperpigmentation endpoint from
consideration. This endpoint was apparently identified as critical in connection with the March
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Mari S. Golub, Ph.D.
1992 meeting of the RfD workgroup. However, tbe June 1992 meeting designates
hyperpigraentation as "not considered adverse". This issue deserves some attention since the
NOAEL would be lower. If hyperpigmentation involves a pathological change in skin, rather
than a compensatory change, it should be considered an adverse effect in my understanding of
the use of the term is risk assessment. I am unclear on the designation of this effect as
"clinical", apparently as opposed to "lexicological". The degree of functional impairment at
the NOAEL is not particularly relevant to determination of adverse since a continuum of
pathology would be expected at higher dose.
Finally, the RfD workgroup analysis of the birthweight data, including gestational age and sex,
is not provided. Additional factors valuable in analysis and interpretation of this effect are
maternal weight gain and maternal age/size. Maternal age/size, sex and gestational age would
be likely to cause group differences in crown-rump as well as weight. Because the products of
conception are a fairly small percent of pregnant weight hi primates, weight gain is not
necessarily tied to fetal weight; however, weight loss could be a relevant factor.
Selection of uncertainty factors
Although the general concept of reduced uncertainty factors and the total UF seem reasonable I
am unclear on the specific rationale presented.
1) Ufa:
I agree that species similarity warrants a reduced safety factor. Since apparently the
only reduction 'consistent with policy is to 3 this is probably appropriate.
2) Ufs:
It was my understanding that subchronic to chronic uncertainty factors were
inappropriate for developmental toxicity studies (USEPA guidelines) because dosing
during brief critical periods can be effective. Although this is an RfD and not an RfDat
(as stated in the notes from the November 1992 workgroup meeting) the same logic
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Man S. Golub, Ph.D.
should apply. Consideration of bioaccumulation may be relevant but this .is not
explained. The RfD documents suggest that the monkeys were in steady state for
accumulation at the time of conception; thus, longer exposure would be irrelevant. I
would appreciate some discussion of chronic vs subchronic developmental toxicity
studies and the role of bioaccumulation.
3) Ufh:
While fetuses in utero may be a sensitive population no rationale for this is presented.
It would seem that nursing infants would be at greater risk at the same level of
environmental exposure due to PCS accumulation in milk. The mention of the use of
nonhuman primates as a iactor hi setting this uncertainty factor is confusing. Shouldn't
this be taken into account in Ufa?
this be taken into account in Ufa?
I agree that a lower than average safety factor is appropriate for this RfD due to
relevant species and sensitive endpoints. I also agree that confidence in the database is
enhanced by the large database on dosing with commercial PCB mixtures and on
environmental PCB exposure in humans. Although male reproductive and
multigeneration studies are lacking, general environmental exposures in domestic and
wildlife populations suggest an opportunity to observe such effects. Further, studies
with commercial mixtures in laboratory animals have demonstrated lowered sperm
counts and lower reproductive organ weights in males at doses in the maternally toxic
dose range for exposed females5.
Weight of evidence conclusions
I agree with the weight of evidence conclusion. Although the database on Aroclor 1016
administration is limited, the database on PCB exposure (secondary evidence) including both
humans and animals is consistent with the selection of this study for the RfD, with the
5 Golub MS, Donald JM, Reyes JA. Reproductive toxicity of commercial PCB mixtures: LOAELs and NOAELs
from animal studies. Environmental Health Perspectives 1991:94;245-253.
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Mari S. Golub, PhD.
NOAEL, and with the rationale for safety factors. Although mechanisms for growth
retardation and developmental neurotoxicity have not been identified, mechanism studies
indicate perturbation of relevant hormonal, metabolic and brain biochemical systems. No
studies demonstrating a lack of effect of Aroclor 1016 at these dose levels on these parameters
are present in the database.
The problem of dosing with commercial mixtures versus environmental media contamination is
a major problem that has been impeding use of scientific information in risk assessment.
Hopefully, the exposure assessment and risk characterization components of the risk
assessment process will be effective in dealing with this issue in specific cases. At the moment
there is no indication that distinct syndromes at distinct dose ranges are produced by exposures
via environmental media as versus commercial mixtures. This is illustrated by the literature on
mink, where a syndrome initially associated with a contaminated food source was reproduced
by administration of commercial mixtures of PCBs.
PARTH. RECOMMENDATIONS
The IRIS RfD entry could profitably be strengthened in areas identified by the committee.
Most likely, this will involve extending rationale in some areas; the materials provided do not
permit the reviewer to reconstruct the basis for the conclusions in the RfD entry. However, it
is possible that revision of the RfD will be warranted because conclusions are not backed up by
a strong rationale. This may be the case for selection of endpoint. Thus, my choice of options
would be either A or C depending on the additional information supplied by RfD workgroup
resource persons at the meeting, particularly on the issue of selection of endpoint. However,
given the extensive previous internal and external review and public comment on the RfD, I
would anticipate that A would be the more likely recommendation at the conclusion of the peer
review.
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Rolf Hartung
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RolfHartung
Comments on the Principal Study
The most disconcerting fact about the reference dose (RfD) for Aroclor 1016 (A-1016) is that it is
based upon a single group of rhesus monkeys (8 animals per dose level) which received 0.25 or 1.0 ppm of
A-1016 in the diet - 8 more animals served as control. Effects were measured in the offspring that were
produced during the 22 month exposure period. Basic questions which were not addressed in the RfD
document are: 1.- what was the food intake and 2.- what where the body weights of the pregnant rhesus
monkeys at the various exposure levels throughout the exposure period?
The 16 exposed monkeys were acquired in 1977, while the 8 control animals were acquired 4 years
earlier in 1973. Aside from similarity in breeding success, there is no assurance of similarities in age, body
weight, condition, or even whether these two groups originated from the same genetic stock. The
appropriateness of the controls is hi question, especially when one is trying to assess subtle quantitative
differences. If the ages or the genetic stock of the control and exposed monkeys were different, then the
differences in a non-specific response, such as birth weights, between exposed and control groups could in
large part be due to such differences, rather than being due to exposures to A-1016. This potential
compromise of the data may even extend to learning and behavioral differences.
The current write-up of the RfD does not assess all of the factors cited above. In my mind there are
unresolved questions regarding the suitability of the principal study and the critical effects that were chosen
for the RfD. Furthermore, questions concerning the reliability of the administered dose must be settled.
Selection of Critical Effects
Bodyweights and birthweights are highly non-specific responses, which are not by themselves
characteristic of a toxic insult, as an elevated serum transaminase level or histopathologic change might be.
This is not meant to assert that body weights or birthweights cannot be used as critical end-points, but it does
mean that it is very important to assess the influences of potential confounding factors. This has not been done
effectively.
The fact that reduced weights were reported in other studies, albeit at much higher doses, is not very
corroberative hi this case. The reason for this is that reduced weights occur at some dose level in almost any
study.
Uncertainty Factors
The selected uncertainty factors are dependent upon the selection of the critical effect and upon the
relevant principal study. If that selection is in question and if other studies br other effects need to be selected,
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RolfHanung
then the uncertainty factors are bound to change as a consequence.
Weight of the Evidence
The Aulerich and Ringer (1977) study in mink suggests an NOEL (not an NOAEL) of 0.4 mg/kg/day
or higher, because this was the highest dose tested and therefore this is a free-standing NOEL.
It is suggested that the number of mink tested in the Bleavins, et al. (1980) was insufficient, even
though the number of mink tested is higher than the number of rhesus monkeys that were tested in the principal
study. We are obviously not very consistent here!
The results of the mink studies are very interesting, but is this the appropriate species to consider?
Is the reproductive physiology of the Mustelidae, with its many examples of delayed implantation and
development, an appropriate model for assessing the reproductive physiology of humans? [R.K. Enders
(1952). Reproduction in the mink (Mustela vison). Proc. Am. Philosophical Soc. 96(6):691-755.].
Furthermore, the mink has been shown to be much more sensitive to tetrachlorobiphenyls than the rat, and
to develop apparently species-specific responses in the form of a necrotizing enteritis [D.M. Gilette, R.D.
Corey, LJ. Lowenstine and L.R. Shull (1987). Comparative Toxicology of Tetrachlorobiphenyls in Mink and
Rats. Fund. Appl. Toxicol. 8:15-22].
Recommendations
My preferred option is £ for the reasons indicated in my comments. .
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Nancy Kim
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Nancy K. Kim, Ph.D.
Part I. Selection of the Principal Study
Given the data base for Aroclor 1016, the choice of principal and supporting studies on which
to base the RfD is reasonable. The issues that have been raised about impurities and
handling of animals are legitimate, but the dose response in birth weight helps to off-set the
importance of these questions.
Although human studies are used to support the finding of reduced birthweight in rhesus
monkeys, one problem with the studies is the apparent inconsistency between the severity
of the effect in humans and monkeys, given similar PCB serum levels. For example, Taylor
et al. estimated that an increase in a woman's PCB serum level from 10 to 20 parts per
billion (ppb) would be associated with a decrease in birthweight of 23 grams (g), or about
0.7 percent given an expected birthweight of 3,300 g. In the 1016 study, an increase in the
mean PCB serum level in rhesus monkeys from 12 ppb (dose level = 0.007 milligrams per
kilogram per day—mg/kg/day) to 27 ppb (dose level = 0.028 mg/kg/day) was associated with
a reduction in birthweight from 486 g to 421 g, a 13 percent decrease. Even though the
studies differ in many ways and each has its own limitations, such a disparity in findings
raises concerns about possible differences in sensitivity between the two species and
suggests additional work on interspecies sensitivities to PCBs is warranted.
Selection of Critical Effects
The selection of low birth weight as the critical effect for Aroclor 1016 is appropriate given
the present data base. The study shows a clear cut effect for the endpoint, a no-observed
effect level (NOEL) and a dose response. The possibility of neurobehavioral effects raises
concern, but given the questions associated with those effects and the studies, it is prudent
to view those results with some uncertainty. The Agency may want to examine these
findings in conjunction with the experts who participated in developing the neurotoxicity risk
assessment guidelines.
The Agency needs to state clearly why it did not use the neurobehavioral effects in
determining the NOEL/lowest-observed effect level (LOEL). The studies are discussed and
the IRIS write-up leaves the impression that PCBs probably did cause the observed
neurobehavioral effects. If so, the Agency should state clearly why these data weren't used
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Nancy K. Kim, Ph.D.
and what additional data are required before the Agency would use neurobehavioral data to
develop an RfD.
Hyperpigmentation was mentioned as being present at birth in both the high and low dose
Infants and it did not persist once dosing stopped. The Agency determined that this was not
a critical adverse effect and the impression is given that at least part of the basis was that
it was transitory. Given that a RfD is meant to be a lifetime exposure level without an
appreciable risk of adverse effects, one could argue that the hyperpigmentation is an
adverse effect, would not be transitory under continuous exposure conditions and should
be considered in the RfD development. Another possible concern is whether a relationship
exists between hyperpigmentation and melanoma, a cancer linked to PCBs in a recent
epidemiological study of capacitor workers.
Selection of Uncertainty Factors - -
The magnitude of the uncertainty factor seems appropriate. However, the Agency derives
the overall uncertainty factor by considering and developing an individual factor for five
areas of uncertainty, and then multiplying them to obtain the overall uncertainty factor. In
the case of Aroclor 1016, the four factors of three lead to an uncertainty factor of one
hundred. One inherent problem-with the Agency's generic process for determining
up.
uncertainty factors is that it requires the "pigeon-holing" of factors that cross the areas of
uncertainty. In the charge of reviewers, the use of a non-human primate (NHP) is given as
the reason for the factor of three for both the uncertainty factor for interspec'ies extrapolation
(UF/») and the uncertainty factor for intraspecies extrapolation (UFH). Its Use on UFA is
appropriate, but its use under UFW seems inappropriate. Moreover, its use implies using an
uncertainty factor of three for UF* for every developmental/reproductive toxicant when the
chronic reference dose is based on effects caused by transplacental exposure. Thus, the
process for choosing an uncertainty factor for a specific toxicant may lead to some generic
policies that are unintended. The selection of the overall uncertainty factor should be
provided in a weight of the evidence approach, without using mathematical formulae. The
basis for setting uncertainty factors should be compared for Aroclor 1016 and Aroclor 1254.
Weight of the Evidence Approach
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Nancy K. Kim, Ph.D.
The weight of the evidence approach described in [he charge to the reviewers and in the
IRIS write-up are similar, but both are somewhat paradoxical regarding the weight of the
evidence given to the neurobehavioral studies. The charge to reviewers states (page 5,
item 1 under Primary Evidence Used for the RfD) that. "The NHP study provides conclusive
data that...neurobehavioral effects is consistent with effects observed in other species,
including humans." However, on page 6 (item 2) it states that. "The behavioral effects were
not chosen as critical given the biphasic nature of the response and the lack of statistical
power in measuring differences to controls." •
Part II. Recommendations
I recommend option B. The RfD value is reasonable, given the existing data. The text
should be rewritten to give a clear understanding of the Agency's rationale for dismissing
the possible neurobehavioral and dermal effects as basis for a RfD.
Because IRIS is used by many people who are not familiar with the toxicological data base
for PCBs, the write-up should be careful to give accurate impressions. For example, the
eighth paragraph under additional studies has the sentence, "due to uncertainties regarding
-actual sources of PCB exposure, and other confounding factors and study limitations, the
decreases in human birth weight cannot be solely attributed to PCBs, particularly specific
PCB mixtures." Having the word 'solely' in the sentence would lead someone unfamiliar
with the Yusho and Yu-Cheng incidents to assume thai the effects were primarily due to
PCBs. In addition, the last sentence of this paragraph overstates the weight of evidence that
PCBs caused birth weight reductions in humans.
The basis behind the selection of the uncertainly factor should be rewritten.
Additional technical issues that could be developed in tho future include comparing
reproductive/developmental effects with serum levels across species and developing
toxicity equivalency factors for reproductive/developmental offocts for individual congeners.
#41190561
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Ralph Kodell
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Review of RfD for Aroclor 1016 Ralph L. Kodell
Part I. Comments.
Selection of Principal Study
The principal study has several weaknesses, but I do not think
that they are serious enough to disqualify the data.
I agree that the low level contamination of the diet with
Aroclor 1048 does not compromise the comparisons of dosed groups to
controls, since the contamination was consistent across treatment
groups, and its concentration was orders of magnitude less than the
levels of Aroclor 1016.
The small treatment group sizes are not that much of a
concern, particularly since there was sufficient statistical power
to detect a difference between the high dose and control. For
monkeys, eight animals per group is a fairly high number.
Exclusion of the lowest dose group from published reports
because of PBB contamination does not appear to compromise the
study.
My main concern, in terms of study design, is the fact that
the animals were not assigned randomly to treatment groups.
Apparently, the animals in the Aroclor 1016 groups all came from a
homogeneous group, but the controls came from a different source.
Presumably, the control animals were older, having been obtained
approximately 4 years before the treated animals. Since there is
a confounding of animal source and Aroclor treatment, it's not
possible to determine either 1) whether the observed effect in the
high dose group was due to Aroclor 1016 or to a difference in
animals, or 2) whether the failure to detect an effect at the low
dose was due to there being no real Aroclor effect, or due to a
difference in animals that masked -the Aroclor effect. Since the
high dose group and low dose group differed significantly from one
another (not shown, but true), it is reasonable to attribute the
effect seen at the high dose to Aroclor 1016. There is less
certainty associated with identifying the low dose as a NOAEL for
Aroclor 1016, although it might be reasonable to do so.
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Ralph L. Kodell
Selection of Critical Effects
Assuming that the principal study is acceptable, then average
birth weight is a relevant response on which to base the RfD. It
appears that the neurobehavioral data support the birth weight
data, in that an effect of Aroclor was detected at the high dose
but not the low dose. The cited human data are consistent with the
reduced birth weight attributed to Aroclor 1016 in the principal
study.
None of the additional studies appears to offer a better basis
for setting an RfD. Certainly, none of them establishes a lower
NOAEL than that in the principal study.
Selection of Uncertainty Factors
The overall uncertainty factor of 100 seems appropriate,
although I would partition it out differently.
UFA: A factor of 3 is justified by the documented
similarities between monkeys and humans. I think 10 would be
unnecessarily conservative.
UFH: I agree that transplacentally exposed infants are a
sensitive subpopulation. Thus, it seems that a factor of 1 could
be justified, and that the present factor of 3 is conservative.
UFD: I believe that the questions raised regarding the
principal study, along with the noted lack of data on other types
of reproductive studies, definitely demand a factor of at least 3.
Since I plan to suggest a modifying factor, I would leave UFD at
the present value of 3.
UFS: I'm not sure what is considered an appropriate duration
for a chronic study in monkeys. But I feel that a factor of 3, as
used, is adequate to cover the uncertainty.
Assuming that the observed effect on birth weight is truly due
to Aroclor 1016, then the small sample size of the principal study
and the confounding of Aroclor treatment with animal source become
more of a concern, since the mean birth weight at the NOAEL was
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Ralph L. Kodell
numerically lower than the control, although not statistically so.
If a benchmark-dose approach were to be used, it is possible that
a value lower than the established NOAEL would be identified as the
benchmark dose. I believe that there is sufficient uncertainty
regarding the design and conduct of the study to warrant a
Modifying Factor of 3.
Thus, although I would lower UFH from 3 to 1 and add a
modifying factor of 3, I would still come out with the same overall
uncertainty factor of approximately 100.
Weight of Evidence Conclusions
I believe that the primary and secondary evidence are well
summarized in Attachment 1. I think that a medium level of
confidence in the RfD for Aroclor 1016 is about right for the
reasons stated in Attachment 1.
Part II Recommendations.
At the present time, I would choose Option B. I think that
the RfD for Aroclor 1016 should be confirmed as presented in the
IRIS entry, but that the text should be revised to include a
broader discussion of data limitations and related uncertainties.
In spite of the limitations of the principal study on which
the RfD for Aroclor is based, I doubt that a better, more
appropriate data set can be identified as the basis for setting a
revised RfD. Also, given the chosen principal study, I think that
birth weight is the most appropriate endpoint on which to base the
RfD. Although I think the principal study does provide the best
data available, I believe that it has sufficient limitations to
warrant applying a modifying factor of 3. However, I would offset
this additional factor of 3 by reducing the UFS from 3 to 1, since
I consider transplacentally treated infants to represent a
sensitive subpopulation. .
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Philip Leber
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P. Leber
COMMENTS CN REVIEW OF RfD FOR Arochlor 1016
A. SiilfclgB:, ftD
, 1994
I. Suitability of Etcpcsed Study (Earsotti) as Basis of RfD
A. Real concerns exist with regards to the adequacy of the published
information en. this study. In. general, sufficient cfc=tr"i is not given in a
nutter of areas to substantiate cause-and-ef f eat findings for Arochlor
1016 and adverse findings in rhesus ncnkeys. ihe bases for this
conclusion are presented below:
1. Characteristic*! of the test chemcal/diet.
mf ornation presented is very sketchy, and inadequate to provide the
reviewer imderstanding of what test animals were exposed to during
study. For exairple, the material was indicated to be Arochlor 1016
without a detailed description of the percentages of not only how many
chlorines were bonded to the diphenyl moiety but which isomers were
found. Ihis is profoundly important as it is new koowi that certain KBs
have TCED-like activity (some was seen in this study) whereas others are
deroid. of this toxic activity.
Secondly, the papers indicate that the test material was devoid of
"dibsnzofurans", citing personal communications with MdKinney. No
mention was made on whether chlorinated dibenzodioxins were looked
for or found. Additionally, the possible presence of these contaminants is
such an important issue that a detailed report on analytical efforts to
evaluate the test material not only for trace amounts of the dibenzo-
furans and -dioxins but also to provide a full qualitative and quantitative
accounting of the makeup of the test substance.
ihe basis for the need for more conprehensive data on test material
identity is nultitudincus. First, if a ftCEL or IOEL is to re darived from this
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P. Leber
type of study, what conclusions can be reached in terms of what caused
the various toxicities? Bar instance, if the material was 90% component A/
8% £, and 1% C_, what is the causative- principle for each toxic response,
A, B, orC? Ms is a pertinent issue in this study- since only certain
(unknown) constituents or metabolites of the test substance,appeared in
maternal or offspring fatty tissues or maternal milk.
Secondly, a perhaps more importantly, how" can the Agency regulate
EOBs on a basis other than on individual iscmar basis? Clearly, if
component Q_ accounts for the toxicity of the test mixture, REDs/RfCs need
to be established for this substance and rot the mixture as a whole, m
the scenario where A and B do not account for significant toxicity, how
would having an RfD for the mixture rationally address health effects,
particularly since the ratios of A, B, and C are likely going to change once
introduced into the environment.
Ihirdly, there is evidence that monkeys were inadvertently exposed
to EBBs, Arcchlor 1248, or unspecified BCBs. wMle it has been estimated
that the' exposures were quite low, it raises a question" of how thoroughly
the diets were examined to ascertain the exclusion of halogenated
dibanzo-furans or -dioxLns. The adverse findings in this study suggest a
potent activity on the part of the test substance, and since it; is known that
there are potential contaminants of PCBs/EEBs that possess the qualitative
Quantitative attributes which could lead to the findings observed in the
study, any conclusions which attribute cause-and-effeet are tenuous until
test diets are unambiguously shown to be devoid of these contaminants.
It was stated that women which were exposed to BCBs 'gave birth to
lower-^weight offspring, and that this information is consistent with the
Barsotti study results. Again, however, it is acknowledged that the
chemical etiology in the human episodes is not clear, and therefore, it is
tenuous to be discussing an RED for the 1016 mixture where only one
component may be important toxicolcgically, both for lab animals and
humans.
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P. Leber
It is concluded that because of incomplete analytical information on the
test material, there are tasks which cannot be performed with any
scientific certainty. The first is a txramLcgical issue which involves the
chemical causation in the Barsotti study. Are the adverse effects
reported related to a KB isomer, and if so, which one(s) and at what
concentrations, or are they related to perhaps to a non-KB (e.g.,
chlorinated dibenzodioxin). Secondly, when NOELs and LOELs are
proposed from this study, and an RED is derived for Arachlor 1016, how
can the Agency apply this reference dose to environmental media which
will be assessed, as containing certain KB isonars. For example, if the
Agency finds 2,3,3',4 tetrachlorodiphenyl chemical in stream sediments
but only has RfDs for Arochlors (mixtures), how can risks be assessed in this
situation? , ,
2. lack of adequate information on test animals.
The "thesis" of Barsotti did. not include certain information on the control
female rhesus monkeys in the study. Because these animals are outbred,
it is iitportant to characterize the test groups and controls as fully as
possible, and to ensure randan assignments of test animals. There is no
evidence that animal randanizations (essential for minimizing bias in this
.type of study) were performad, either for maternal or paternal monkeys.
AcbHticrally, initial and weaning body weights for dams were given only
for KB test groups but not controls. Since offspring weights can be
related to maternal body weight (BW), inclusion of these data are
inportant if deficits in the offspring are being used as a criterion for
adverse effects. Descriptions of procedures on health status that are
normally carried out during quarantine periods, breeding and dosing
schedules,- male and female mating histories and design of pairings of
rhesus monkeys, were also absent.
Although birth weight deficits can be a legitimate adverse effect for
basing risk assessments, the 6 and 15% decreases in this parameter
appear to be very "soft" findings in this study because of the apparent
heterogeneity of the maternal population (BMs, lengths of time within the
colony, age?, other unknowns), and the low number of animals in the test
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P. Leber
groups. In addition, although the infants continued to be eocposed via
maternal milk to Arochlor, 17^week data indicate that the BW difference
between controls and high-dose rhesus were virtually eliminated. In other
.wards, it may be expected that this gap would have widened as infants'
exposures continued.
3. Uncertainty Factors
mterspecies (UFA)
The rhesus is very sensitive to the effects of KB products as is the human.
However, before assuming that a value of 3 is needed which implies that
the human is more sensitive, a cotparison between thresholds or
sensitivities for effects such as chloracne or neurological effects may
indicate that a value of _l_is appropriate.
Intraspecies (UFa)
It's true that transplacentally-exposed infants appear to be a sensitive
population. A value of_3_is appropriate for the uncertainty factor.
Overall Database (UFD)
Since developmental endpoints appear to represent the most sensitive
endpoint for exposure to Arcchlor 1016 and this has been evaluated in a
species which has a susceptibility similar to that of humans, a factor of 3 s
quite adequate for this category.
Lack of Chronic Data (UFs)
The Agency acknowledges that animals in the Barsotti study were
exposed to "steady state" levels, and that consistent with human findings,
developmental effects are likely the most sensitive effects from exposure
to these agents with chronic testing not likely leading to a lower NDAEL.
It is proposed that given the partial accounting for the dewelcpnental
endpoint in the UFD factor of 3 presented above, a value of_l_appears to
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P. Leber
be adequate. Nb otbsr toxLcities were noted other than those
considered to be "developmental" in the 22 month study.
Because of the evidence that rhesus are a very sensitive species, and
that the developmental endpoint appears to be represent a most
sensitive finding following exposures to PCB products/ an overall UP of 10
Applied to the 1OVEL for the study appears to be scientifically justified.
4. Weight of Evidence
Study
It appears that the exposure of pregnant montosys to a test diet which
contained chemicals including those in Arochlor 1016 led to adverse
effects in offspring. Hawever, in the determination of an RED for Arochlor
1016 per se. the confidence in this study is considered low. This isbasasl in
part upon the fact that, qualitatively and quantitatively, there are many
laacertainties in the ccnpositions of the test material and diets. 3ii
addition, as it was stated in cotmunications for this review, the 1016 is
expected to be less toxic than the more highly chlorinated products.
However, this study denonstrated very high potency for 1016, raising the
question whether effects are related to the main components (BCB
isoners) or trace contaminants.
Data Base
Unquestionably, adverse effects have been observed in many species
including humans as a result of exposure to PCS products which may
include certain highly potent reaction products that interact at dietary
concentration in the ppb range with the TCDD receptor to cause an array
of taxacities. It is also kncwn that certain KB isomars have greater
toxicity due to certain ranformational features. VJhile data exist which
support the findings in the Earsotti study, conclusions addressing chemical
OTuse-ard-effect also exist in this literature. Again, in the determination
of an RED for Arochlor 1016 par se. the confidence in this informaticn is
considered low.
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P. Leber
RfD " ' • .
Overall, the confidence in the RED must be considered low.
5. Recommendation for Action. , .
Potion D
l&r suggestion is to consider RfDs for components of KB products
according to findings for individual coiponents. While this may at first be
considered, to be tedious (given the nultitude of isoners), invite) and
modern conputer SAR techniques are approaching adequacy for
ranking these discrete chemicals in terms of toxic actions. Using
databases from "purer" PCBs will be needed. Such an approach avoids
the substantial problems posed by (a) trying to develop RfDs when relying
solely on data derived on chemical mixtures such as that developed by
Earsotti, and (b) applying RfD values to PCB contamination scenarios
where the chemical analytical findings cannot be related to discrete
products (e.g., Arochlor 1016 ). While there may be occasions where only
one source of contamination is likely (as is suggested), the makeup of the
contaminated media will be constantly shifting. Attempted application
of an RfD derived from a "mixture" tax study to an environmental media
"mixture" condition appears to be a scientifically untenable exercise.
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John Moore
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John A. Moore
Part I. Comments
SELECTION OF THE PRINCIPAL STUDY
The reference dose document clearly states that the critical effect selected was reduced birth weight. Thus
the primary data source is Dr. Barsotti's doctoral thesis, a secondary source is the Barsotti and Van Miller
(1984) article in Toxicology that drew from her thesis data. The Schantz et al. (1989) (1991) and Levin et
al. (1988) papers do not reflect data from the Barsotti thesis. Rather, they reflect studies performed on
some offspring from the Barsotti research that was performed at later time periods. Statement 1 on page 2
of the Charge to Reviewers should be corrected to reflect these facts.
The Charge To Reviewers states that the principal study must be of "sufficient quality." While the term is
not further defined, sufficient quality must be judged in the context of its proposed use in a risk assessment.
In this instance there is a need to 1) critically assess the certainty that Aroclor 1016 does affect infant
primate birth weight, and 2) review the logic applied in quantitatively extrapolating from experimental data
to establish a value relevant to human health. Several issues merit review that are summarized below.
COMPARABILITY OF CONTROL AND TREATMENT GROUPS:
Issue: Birth weight is known to be affected by maternal age, parity, and nutritional status, factors
that were not controlled in allocating monkeys to either control or treatment groups or within
treatment groups.
Discussion: All primates were identified as feral animals with no reference as to geographic
habitat or country of origin. Dr. Barsotti was quite clear in stating that the control monkeys were a
group that had been in captivity since 1973 and that the animals used in the Aroclor 1016 dose
groups were received from shipments in 1976 (7/21/76 and 10/20/76; Table 2-2, page 56 of
thesis).
It was stated that some of the animals appeared younger than others which was clarified by
irregularities in their menstrual cycles (thesis page 185). It was further stated that because of this
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John A. Moore
immaturity nine months were required before regular menstrual cycles were established. No such
issues'were raised in a discussion of the control monkeys.
Concern: An Aroclor 1016 "effect" was determined by a comparison of birth weights from treated
and control groups. The treated and control groups had a number of important differences other
than exposure to Aroclor 1016. Treated and control monkeys differed by several years as to. length
of time they were in a closely controlled environment and fed a standard laboratory diet. Given the
three-year difference in dates of receipt, it is reasonable to assume that the controls were older than.
the treated monkeys. It is quite probable that there was a difference in reproductive parity between
control and treated monkeys. It is known that there were significant age differences within the
group of primates that were assigned to one of three treatment groups; there is no indication that
allocation within treatment groups considered this factor. • Small group size could magnify any
effect due to this factor.
CHEMICAL CONTAMINATION
Issue: General procedures in use at the time were not sufficiently stringent to preclude cross
contamination between studies with PCBs, PBBs or TCDD. There is substantial reason to believe
such events occurred in the Aroclor 1016 study which call into question any judgment that there
was a clear causal relationship between exposure to the test material and reduced birth weight.
Background: Barsotti acknowledged that the Aroclor 1016 group that received 0.025 ug/gm in the
diet had, through procedural error, received a PBB diet for an unknown period of time. This error
was detected when unexpected peaks were observed in gas chromatograms of tissues although no
chromatograms were found in the thesis to verify the point.
Barsotti acknowledged in her thesis that the commercial diet used at the primate center contained
low levels (0-50 ppb) of PCB which they characterized as being similar to Aroclor 1248.
The toxic effects of Aroclor 1248 were studied at Wisconsin, indeed these studies constituted the
major portion of the Barsotti thesis. Aroclor 1248, which contains a much greater proportion of
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John A. Moore
contaminant, attain levels in control animals equivalent to the mean levels observed in 5 mothers at
parturition who had consumed a diet containing 0.025 ug/kg for over a year (Table 6-1, page 207
of thesis). The control diet was reported to contain Aroclor 1016 only at the limit of detection
(0.005 ug/gm).
Table 6-4 (thesis page 210) lists two control infants as having Aroclor 1,016 skin levels (fat basis)
of 1.0 and 2.07 ug/gm which is well within the range reported for the 7 infants born of mothers
who had been fed a diet that contained 0.25 ppm Aroclor 1016 for almost a year. This does not
track at all with what is known about the pharmacokinetics of these materials. It does raise
questions about what exactly was the maternal exposure.
SELECTION OF CRITICAL EFFECTS
For all of the reasons outlined in the previous section, selection of lower birth weight can not be considered
a critical effect with even a small degree of confidence.
Section 7 of the material provided to us contains material associated with a 06/23/92 RfD/RfC Work
Group meeting. In that document it is stated that HERL/NTD reviewed the neurobehavioral data,
concluded that because the dosed groups did not differ significantly from the controls neurotoxicity should
not be considered a critical effect. It further stated that Dr. McPhail had reviewed the Schantz et al. (1989)
(1991) and Levin et al. (1988) papers in reaching the above conclusion.
While it would have been of value to have included Dr. McPhail's written review in the material provided to
us, it must be assumed that he represents the scientist with the best qualifications to critically review such
data. It was noted that despite the extensive number of meetings held to review this data, the individuals
who actually reviewed the material and their qualifications and experience were never identified; in fact
those who attended meetings apparently were not recorded.
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John A. Moore
SELECTION OF UNCERTAINTY FACTORS
It is not apparent that an uncertainty factor needs to be applied based on the logic that this is a less than a
chronic study. A study that has a dose regime that spans almost an entire year would seem to qualify as
chronic especially since there was data presented that indicated steady state tissue levels were reached after
about four months of dietary exposure.
WEIGHT OF EVIDENCE CONCLUSION
Primary evidence: The material provided disputes the statement on page 5 of the Charge to Reviewers, i.e.,
there was no conclusive evidence of neurobehavioral effect. Further, there are no human data that identify
Aroclor 1016 as having neurobehavioral effect. There is little certainty of judgment associated with
extrapolating results from higher chlorinated PCBs to results observed with lower mixtures.
Partn. Recommendation
Option D. Withdraw the RfD for Aroclor 1016 and state that there is insufficient data to permit the
establishment of such a value for this PCB mixture.
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James Olson
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James R. Olson
5/2/94
Comments Regarding the RfD for Aroclor 1016
Aroclor 1016 is a commercial mixture of PCBs containing about 41% chlorine by weight.
The Drinking Water Criteria Document for PCBs ( US EPA, 1989 ) summarized the relative
composition of Aroclor 1016 as containing 1% mono Cl, 20% di Cl, 57% tri Cl, 21 % tetra
Cl, and 1% penta Cl biphenyls. A comprehensive list of individual congeners was not
included in this document. PCB Congeners representative of Aroclor 1016 have been
detected in finished drinking water obtained from the Hudson River and samples from well
water taken during the National Organic Monitoring Survey ( US EPA, 1989 ). Since PCBs
are always present in biological and environmental specimens as a complex mixture of
individual congeners, with varying pharmacokinetics and environmental persistence, it is
most of the time not possible to specify PCB levels in terms of a specific commercial
formulation, such as Aroclor 1016. While this is a major limitation of developing a RfD for
Aroclor 1016, there are few alternatives based on the available scientific data.
-It would be useful to define the chemical composition of Aroclor 1016 in greater detail in
the RfD Summary.
-The RfD Summary should also contain some discussion of the limitations associated with
giving a RfD in terms of a complex commercial formulation.
Selection of Principal Study
The principal study used for the Aroclor 1016 RfD was published 'as four periodic reports
on a single group of rhesus monkey mothers and their offspring, including follow-up data for
up to four years after birth ( Barsotti and van Miller, 1984; Levin et ah, 1988; Schantz et
al., 1989; Schantzetal., 1991).
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J.R. Olson
The following comments are related to problems associated with the above studies.
Selection of Controls:
Eight animals purchased in 1973 were used as controls, while 16 animals acquired in
1977 served as experimentals (Barsotti and van Miller, 1984). All animals were purchased
from the same supplier. There remains a question as to whether the Aroclor and control
exposures occurred during the same time. If the entire study was conducted at the same
time, the control animals had 3-4 years longer to acclimate to the laboratory conditions.
Data on the age and body weight of the control animals was also not provided. This is of
concern since body weight data on the Aroclor exposed adult female monkeys was given
prior to exposure and at weaning ( Table 6-8, p 214 of Barsotti's
dissertation); Birth weight could vary with the age and body weight of the animal. In
addition, no data were given on the reproductive history of the animals. Birth weight could
also vary with the number of prior pregnancies which resulted in live births. Perhaps it
would be possible to get answers to these questions.
Although some questions remain regarding the control group, the data support a dose
related decrease in the birth weight of the offspring with exposure to Aroclor 1016. A
significant decrease was reported between the control and high dose group. Furthermore,
there was a significant decrease in birth weight between the high (1 ppm in food) and low
(0.25 ppm) exposure groups ( p < 0.001, unpaired t-test). Aroclor 1016 concentrations in
the skin of the infants at birth further confirms the dose related transplacental exposure of the
infants to Aroclor 1016.
Dosing and Contamination Issues:
In the original study, a 0.025ppm 1016 in the food exposure group was also included.
Published data from the study did not include this group due to PBB contamination in this
diet. This problem was'identified by the authors because they conducted extensive analysis
of animal tissues and diet during the study and discovered the PBB contamination.
The ubiquitous presence of PCBs appears to be responsible for the monkey chow
containing from 1-50 ppb PCBs based on an Aroclor 1248 standard. The higher chlorinated
PCBs were found in control and experimental diets and tissues.
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J.B. Olson
Dosing and contamination issues are of some concern but appear to be largely due to the
ubiquitous low level persistence of PCBs in the environment. The strength of the study is
still the dose related decrease in birth weight which is related to tissue levels of Aroclor 1016
in the infants. Another strength of the study is the extensive chemical analysis of the diet
and animal tissues, confirming exposure to Aroclor 1016.
Although there are problems associated with these studies, these factors do not appear at
this time to disqualify use of these reports as the principal study.
Selection of Critical Effects
Reduced birth weight in the rhesus monkeys in the principal study was identified as the
critical effect for the RfD. As stated above, there was not only a significant decrease in
birth weight in the high exposure (Ippm) group relative to the control, but also between the
high exposure (Ippm) and low exposure (0.25ppm) group. The dose related decease in birth
weight was also directly related to tissue levels of Aroclor 1016 in the infant monkeys at
birth. Thus, tissue dosimetry data is available to directly confirm the transplacental exposure
of the new born monkeys to Aroclor 1016.
The reduced birth weight reported in Barsotti and van Miller (1984) was also used as the
key study to obtain a RfD for Aroclor 1016 in the Drinking Water Criteria Document for
PCBs ( US EPA, 1989).
Neurobehavioral effects and transient dermal pigmentation attributed to Aroclor 1016 in
the principal study have also been reported in other monkey studies with PCB exposure and
in humans with PCB exposure. The RfD Summary provides a good overview of related,
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J.R. Olson
supportive studies.
Selection of Uncertainty factors
The total UF of 100 appears appropriate based on the 4 areas of uncertainty considered in
the RfD. A UF of 100, based on other considerations, was also applied in calculating the
RfD for Aroclor 1016 in US EPA, 1989.
Weight of Evidence Conclusions
The RfD Summary supports the medium degree of confidence in the Study, Data Base,
and RfD.
PART II Recommendations
At this time, based on my review and the above comments, I would favor Option A or B.
Confirm the Aroclor 1016 RfD value as presented in the IRIS entry, but revise the text to
include limitations, uncertainties, and other recommendations made during the peer review.
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Stephen Safe
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Stephen H. Safe
Review: Technical Review Workshop on the Reference Dose for Aroclor 1016
Reviewer: Dr. S. Safe
Veterinary Physiology and Pharmacology
Texas A&M University
College Station, TX 77843-4466
TEL: 409-845-5988 / FAX: 409-862-4929
Attachment 1 briefly outlines the principal and supporting studies which are being utilized to
derive the RFD values for the PCB mixture, Aroclor 1016. Based on the known characteristics and
composition of Aroclor 1016, there were some unusual and unexpected effects noted in these
animals, namely:
(i) the apparent dose-dependent decrease in body weight in control (528 g), low dose (486 g)
and high dose (421 g) infants and
(ii) hyperpigmentation in the low and high dose infants which did not persist.
s
There is good evidence that the effects noted above tend to be associated with aryl hydrocarbon
(Ah) receptor-mediated responses caused by aromatic hydrocarbons including polychlorinated
biphenyls (PCBs), dibenzofurans (PCDFs) and dibenzo-p-dioxins (PCDDs). Moreover, examination
of recent analytical data reported for Aroclor 1016 and the results of other feeding studies with
Aroclor 1016 and other Aroclors indicate that the data reported by Barsotti and coworkers are
problematic. A brief discussion of the inconsistencies between the studies utilized for deriving the
RFD and other data is noted below. The major reason for this discussion is to point out the
discordance between the observed data (i.e. hyperpigmentation and body weight loss) and the
results expected for Aroclor 1016.
Aroclor 1016 - Analytical Data. Aroclor 1016 was prepared as a blend of PCBs which
primarily contained di-tetrachlorpbiphenyl congeners and virtually none of the higher chlorinated
biphenyls which are found in mixtures such as Aroclor 1242 which has a similar chlorine content (by
weight). This is clearly illustrated in the paper by Schulz et al. (Environ. Sci. Technol. 23, 852, 1989)
who reported the high resolution analysis of Aroclors 1221, 1016, 1242, 1254 and 1260 and several
Clophen mixtures. A similar chromatogram has been reported by Wolff and coworkers (Toxicol.
Appl. Pharmol. 49, 199, 1982; Environ. Health Persp. 60, 133, 1985). Moreover, in the study by
Wolff and coworkers, the gas chromatographic pattern observed in Aroclor 1016-exposed workers
is similar to the pattern for Aroclor 1016. In contrast, the PCB gas chromatographic pattern
observed for various fat extracts from Aroclor 1016-exposed monkeys (Barsotti and Van Miller)
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Stephen H. Safe
shows at least 3 higher molecular weight PCBs which are not detected in Aroclor 1016. These
peaks are routinely detected in fat samples from animals treated with higher chlorinated PCS
mixtures suggesting that the animals used in this study were exposed to higher chlorinated PCBs
(or-PCB mixtures) in addition to Aroclor 1016. These PCBs may have been present as impurities
in the feed or in Aroclor 1016 or in the monkeys used in this study. These analytical data suggest
that the animals used in the Barsotti and Van Miller study were exposed to Aroclor 1016 and higher
chlorinated PCBs and therefore standard setting (I.e. RFD) for Aroclor 1016 based on this study is
problematic.
Aroclor 1016: Predicted versus Observed Toxicities. High resolution GC analysis of
Aroclor 1016 (Environ Sci. Technol. 23, 852, 1989) also shows that relatively low levels of the
"dioxin-like" (Ah receptor agonists) coplanar and monoortho coplanar PCBs are present in these
mixtures compared to that observed for higher chlorinated commercial PCE3s. Using a toxic
equivalency factor (TEF) approach, "dioxin" or toxic equivalents (TEQs) for Aroclor 1016 are low (<
1 ppm?) compared to the values for Aroclors 1242 (696 ppm), 1254 (146 ppm) and 1260 (53 ppm)
(Safe, C.RC. Crit Rev. Toxicol., in press, 1994). For example, recent studies in my laboratory have
determined the dose-response induction of hepatic microsomal EROD activity (an Ah receptor-
mediated response) in .female Sprague-Dawley rats. The results showed that at a dose of 50 mg/kg
only minimal induction was observed for Aroclor 1016. The relative potencies of the Aroclors roughly
paralled their TEQs (Safe, 1994 and unpublished results).
EROD Induction in the Rat by Aroclors.
Treatment
Aroclor 1260
Aroclor 1254
Aroclor 1242
Aroclor 101 6*
EROD Activities (pmol/mg/min)
dose (mg/kg) 0
14 ±3
80 ±16
78 ±11
82 ± 6.6
0.5
16 ±7.3
93±30
104 ±31
84 ± 7.3
5.0
34 ±13
218 ±177
465 ± 545
76 ±16
50
149-± 78
4243 ± 524
2692 ± 1293
124 ± 20
* induction is increased at higher doses and this may be related to induction of CYP1A2.
Not surprisingly, the results reported in I.A.4. ADDITIONAL STUDIES/ COMMENT (ORAL RFD) of
Attachment 1 show that the typical "dioxin-like" effects of Aroclor 1016 such as body weight loss and
hyperpigmentation are not observed whereas in studies with higher chlorinated PCBs, these effects
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Stephen H. Safe
are reported. This point is noted by Barsotti and Van Miller (pp. 40 and 41); however, they do report
some decreased body weights and hyperpigmentation suggesting that these effects may be
associated with the higher chlorinated PCBs which have contaminated this study.
In my opinion, there is a problem in setting an RFD value for Aroclor 1016 when some of the
observed responses may be associated with PCBs other than Aroclor 1016.
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Richard Seegal
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Richard F. Seegal
Part One: Reviewer Comments.
Charge #1. Selection and Use of Non-human Primate (NHP) Reports as the Primary Basis for
Aroclor 1016 RfD.
The reports listed in Attachment #1 (Barsotti and van Miller, 1984; Levin et al, 1988; Schantz
et al., 1989; Schantz et al., 1991) provide in-depth analysis of the reproductive and neurobehavioral
consequences of perinatal exposure of Macaca mulatto (rhesus macaque) to Aroclor 1016. Because the
developing organism is most sensitive to exposure to putative toxicants (Tilson et al., 1990) and because
the NHP metabolizes polychlorinated biphenyls (PCBs) in a manner similar to humans (Matthews and
Dedrick, 1984), these studies provide an appropriate basis for setting RfDs for Aroclor 1016.
Although these studies originated from a single laboratory and have not been replicated in other
laboratories, the dose-related deficits in birth weight and discrimination reversal learning are sufficient
to conclude that low-dose perinatal exposure to Aroclor 1016 may induce adverse health effects in
humans. This conclusion is based on the following lines of evidence.
a. Perinatal exposure to 1 ppm of Aroclor 1016 resulted in significant decreases in birth
weight (Barsotti, Thesis, Table 6-3, p. 209). Decreases in birth weight were reported only in the high-
dose animals. However, examination of the summary data in that table suggests that there are also
significant differences between the high and low dosed offspring (422 g vs. 491 g) — i.e. a dose-
response relationship. Thus, General Electric's (GE) comments that control animals were 'not
adequately matched to experimental animals, had longer to acclimate to laboratory conditions and may
have been obtained from different geographic sources' appear to be unfounded since birth weight
differences exist between low and high dose 1016 animals obtained at the same time and maintained
in the laboratory for the same time period.
b. Errors due to cross contamination of Aroclor 1016 chow with either polybrominated
biphenyls (PBBs) or Aroclor 1248 were identified and appropriately handled. GE states that
'congeners with relative retention times (RRTs) of 125 and 146 were present in both the milk of
monkey mothers and infants' adipose tissue'. Barsotti, in her thesis, noted that primate chow contained
1-50 ppb of Aroclor 1248. This level of contamination is not uncommon and most likely reflects low-
level contamination of the primate chow. If this was the source, all NHPs, including controls, would
have been exposed to the same contaminants. If the 1248 congeners were present in the original
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Richard F. Seegal
Aroclor 1016 mixture, they were present at concentrations of between 1 and 50 ppb. At that level of
contamination, the high dose Aroclor 1016 animals, exposed to 1 ppm of Aroclor 1016, would have
been exposed, at most, to 50 parts per quadrillion of congeners derived from Aroclor 1248.
Inadvertent exposure of low dose Aroclor 1016 animals to PBBs was detected when adipose
and milk samples were analyzed for PCBs. These animals were withdrawn from the study and any
potential concerns over co-exposure are not relevant to addressing the 'fitness' of these studies in setting
RfDs for Aroclor 1016.
c. Concerns over possible erroneous dosing of either or both Aroclor 1248 and Aroclor
1016 exposed animals may be due to differences in the ability of congeners present in these
mixtures to induce hepatic enzymes and enhance metabolism of parent congeners.
GE states that 'newborn offspring from NHPs fed Aroclor 1248 in their diet had an average
level of PCB in skin-adipose of 2.8 jtg/g while offspring from mothers exposed to 1 ppm of Aroclor
1016 had an average of 3.37 ppm'. GE concludes that this anomalous finding was due to erroneous
dosing. However, there are two reasons for discounting these statements. First, the degree of variance
in the measures of the PCB residues indicates "that there may be no significant differences in body
burdens. Secondly, concentrations of mono-ortho and coplanar congeners are much greater hi Aroclor
1248 than in Aroclor 1016 (Hong et al, 1993). Based on toxic equivalent factors (TEFs), (Safe, 1987),
Aroclor 1248 contains approximately 300 tunes the TEF equivalents of Aroclor 10l6 (Hong et al.,
1993). In addition, Aroclor 1248 exposed animals received 2.5 times the dose level of Aroclor 1016
animals, resulting in approximately a 750 fold greater exposure to PCB congeners that induce aryl
hydrocarbon hydroxylase activity and enhance the metabolism of mono-ortho and coplanar PCBs.
Furthermore, the three persistent congeners present in Aroclor 1016 (2,4,4'; 2,4,2',4' and 2,5,2',5') are
also present at similar concentrations in Aroclor 1248 and would accumulate at the same rate. Based
on these differences in metabolic potential between Aroclor 1248 and Aroclor 1016, it is highly unlikely
that erroneous dosing, in either the Aroclor 1248, or more importantly, in the Aroclor 1016 exposed
animals is responsible for the observed differences in skin/adipose concentrations of PCBs.
d. Adult exposure of Macaca nemestrina, pig-tailed macaques, to higher levels of Aroclor
1016 resulted in significant decreases in regional brain dopamine (DA) concentrations (Seegal et al.,
1991). Although these doses (0.8, 1.6 and 3.2 mg/kg/day) were significantly higher than those used in
the Barsotti-derived animals, chemical analyses of serum concentrations of PCBs demonstrated that
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Richard F. Seegal
these levels were .similar to those seen in workers occupationally-exposed at the GE Fort Edwards
factory (Lawton et al., 1985). Furthermore, w,hen similarly treated high-dose animals were removed
from exposure for 24 weeks, brain and serum levels of PCBs decreased dramatically, hi the absence
of any return to control levels for brain DA. These findings are important since experimental alterations
in brain DA concentrations have been shown to alter learning and memory process in both NHPs and
rodents (Sawaguchi et al, 1988; Archer et al, 1988).
e. Chemical analysis of PCB residues in the brains of Aroclor 1016 sub-chronically treated
adult NHPs reveal the presence of only three congeners (BZ #28, 47 and 52) (Seegal et aL, 1990).
These findings are remarkably similar to the tissue residues seen in both adult and perinatally-exposed
Aroclor 1016 animals by Barsotti (Thesis; Barsotti and van Miller, 1984). When cells hi culture were
exposed to these congeners, either alone or as a mixture that reflected the congener ratios seen in NHP
brain, there were significant decreases in cellular DA concentrations (Seegal et al, 1990). Further
studies by Shain et al (1991) have demonstrated that lightly chlorinated, ort/zo-substituted congeners,
but not dioxin-like congeners, also significantly reduce cellular DA concentrations.
In addition, in studies underway, perinatal exposure of rats to 2,4,2',4' results in significant
decreases in brain DA concentrations, reinforcing the finding that congeners derived from Aroclor 1016
are capable of altering central nervous system biogenic amine function. In turn, these neurochemical
changes would be likely to affect the neurobehavioral dependent variables.
Charge #2. Selection of Critical Effects: Low Birth Weight versus Neurobehavioral Changes.
Perinatal exposure to 1 ppm of Aroclor 1016 resulted in a 15-20% decrease in body weight.
However, there were greater absolute decreases in body weight between the low dose and high dose
animals than between controls and low dose animals. These results suggest that the Aroclor 1016
induced decreases in body weight would have been evident even without comparisons to the control
animals.
A more sensitive measure of perinatal exposure to Aroclor 1016 is provided by examination of
the discrimination reversal data presented in papers by Schantz and Levin. In these papers the
investigators determined that exposure to 1 ppm of Aroclor 1016 resulted in a 2.5 fold increase hi the
number of original learning trials required for perinatally-exposed NHPs to reach a criterion of 9/10
correct trials. The magnitude of these changes are obviously much greater than those seen for
alterations in birth weight and strongly suggests that alterations in behavior may be a more sensitive
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Richard F. Seeeal
measure of toxicant exposure than decreases in body weight. Indeed, NHPs with lesions in the
dorsolateral area of the prefrontal cortex show a pattern of deficits that are very similar to those
observed in the 1 ppm Aroclor 1016 exposed offspring (deficits on original learning and early reversals,
but no deficits on later reversals). The similarity between the behavioral deficits induced by perinatal
exposure to Aroclor 1016 and discrete lesions of the prefrontal * cortex emphasize the validity of the
discrimination reversal task in detecting alterations in cognitive function in NHPs and minimize
concerns over the lack of statistically significant differences observed between the 1 ppm Aroclor 1016-
exposed offspring and control animals on later reversal problems. This point needs to be further
developed and stressed.
Charge #3. Uncertainty Factor Analyses for Aroclor 1016.
In Attachment #5 'Charge to Reviewers for the RfD for Aroclor 1016' four areas of
uncertainty are assigned factors ranging from 1 to 10. The RfD work group has assigned uncertainty
factors (UF) of three for all areas of uncertainty resulting in a total UF of less than 100. The total UF
is less than the average for other agents examined by the RfD. However, it is suggested the UFD and
UFS be further reduced because of the following evidence.
For UFD a factor of three was assigned because studies 'relating to male reproductive effects
and two-generation reproductive studies were not available'. All offspring were sired by unexposed
males (Schantz et aL, 1991) and hence the possibility of male-induced reproductive and neurobehavioral
deficits can be ruled out. Furthermore, statistical analyses of 'paternity effects' were conducted and no
evidence of male-induced effects in offspring were found. Hence, there is no statistical evidence that
possible male-induced reproductive alterations were responsible for any of the observed effects on birth
weight or neurobehavioral change. I suggest that UFD be changed from three to two. If two-generation
reproductive studies had been carried out the UFD could have conceivably resulted in further decreases
to one.
For UFS, an uncertainly of three was assigned because the duration of exposure was not of
sufficient duration to warrant being called a 'true' chronic study. However, exposure to 1 ppm of
Aroclor 1016 for 21.8 months appears to be of sufficient duration to result in steady state levels being
reached in the mothers. This statement is based on the lack of statistically significant change in Aroclor
1016 milk concentrations in the 1 ppm exposed female NHP throughout the four month period of
lactation. If steady state levels had not been reached, continued exposure to Aroclor 1016 during
lactation would have resulted in a further elevation in Aroclor 1016 concentrations. Thus, the
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Richard F. Seegal
statistically significant doubling of Aroclor 1016 milk concentrations seen in the 0.25 mg group argues
that steady state levels had not been achieved in the lower dose animals.
Charge #4. Weight of Evidence Conclusions: Data Consistent with RED Conclusions.
Conclusions based on review of Attachment #1 and the four key papers provide sufficient
weight of evidence that perinatal exposure to Aroclor 1016 may yield significant adverse health effects
in humans. This statement is based on the following lines of evidence
a. Perinatal exposure to 1 ppm Aroclor 1016 results in significant decreases in birth weight of
exposed offspring and a 2.5 fold increase in the number of trials required to reach criterion on a
discrimination reversal task. These data alone, should be sufficient to reach the conclusion that the RfD
for Aroclor 1016 is scientifically valid.
b. Additional data gathered in adult NHPs exposed to Aroclor 1016 demonstrates that congeners
present in this commercial mixture are sufficient to significantly alter brain DA concentrations and that
these decreases persist following removal of the animals from exposure (Seegal et al, 1994).
Experimental alterations of DA concentrations in the prefrontal cortex of NHPs resulted in deficits on
cognitive tasks similar to those seen with exposure to Aroclor mixtures, reinforcing the importance of
the findings that exposure of NHPs to Aroclor mixtures, including Aroclor 1016, induce cognitive
deficits by altering brain concentrations of DA.
Data Less Consistent with RfD Conclusions.
Although 'there is difficulty in assessing human response-exposure to a mixture of congeners',
data gathered by Seegal et al. (1991, 1994) following sub-chronic exposure of NHPs to Aroclor 1016,
as well as the original chromatographic data from Barsotti (Thesis) ('peaks with RRTs of 37, 47 and
70 comprised the majority of the PCBs representing approximately 80% of the Aroclor 1016')
demonstrate that there is a selective accumulation of a small number of Aroclor 1016 congeners.
Indeed, Schantz et al. (1991) state that the RRT peak 37 consists 'primarily' of 2,4,4' while RRT peak
47 includes 2,4,2',4' and 2,5,2',5'. Using high-resolution glass capillary gas chromatography, we
(Seegal et al., 1990) have shown that congeners accumulating in the NHP following adult exposure to
Aroclor 1016 are 2,4,4'; 2,4,2',4' and 2,5,2',5'. Thus, the animals exposed by Barsotti et al to Aroclor
1016 accumulated the same congeners. Although in-vivo exposure to these three congeners has not yet
been conducted, we have shown that in-vitro exposure to the three congeners that accumulated in NHP
brain significantly reduced cellular DA concentrations. We suggest that chemical analyses of target
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Richard F. Seeeal
organs or body burdens following exposure to complex mixtures of congeners will provide more insight
to the lexicological actions of the congeners and considerably less confusion than examination of
congeners in the original dosing mixture.
Part Two: Recommendations.
I prefer a combination of Options A and C for the following reasons.
Based on statements made hi the above text, I strongly feel that the criticisms raised by General
Electric Corporation concerning the possible cross-contamination of the diets and the use of
inappropriate control groups are not based on an accurate reading or interpretation of the data presented
in the key articles. Thus, Option A would be the appropriate recommendation.
However, the statistically-significant deficits seen in the Aroclor 1016 exposed animals during
the original learning of the discrimination reversal learning tasks strongly suggests that the
neurobehavioral data should be incorporated or 'factored' into the RED for Aroclor 1016. Hence, the
reason for also recommending Option C.
-------
Richard F. Seegal
Literature Cited
Archer T, Danysz W, Fredriksson A, Jonsson G, Luthman J, Sundstrom E, Teiling A. Neonatal
6-hydroxydopamine-induced dopamine depletions: Motor activity and performance in maze learning.
Pharmacol. Biochem. Behav. 1988; 31:357-364.
Barsotti DA, Van Miller JP. Accumulation of a commercial polychlorinated biphenyl mixture (Aroclor
1016) in adult rhesus monkeys and their nursing infants. Toxicology 1984; 30:31-44.
Hong C-S, Bush B, Xiao J, Qiao H. Toxic potential of non-ortho and mond-ortho coplanar
polychlorinated biphenyls in Aroclors, seals and humans. Arch. Environ. Contain. Toxicol. 1993;
25:118-123.
Lawton RW, Ross MR, Feingold J, Brown JF,Jr.. Effects of PCB exposure on biochemical and
hematological findings in capacitor workers. Environ. Health Perspect. 1985; 60:165-184.
Levin ED, Schantz SL, Bowman RE. Delayed spatial alteration deficits resulting from perinatal PCB
exposure in monkeys. Arch. Toxicol. 1988; 62:267-273.
Matthews HB, Dedrick RL. Pharmacokinetics of PCBs.^nw. Rev. Pharmacol. Toxicol. 1984; 24:85-103.
Safe S. Determination of 2,3,7,8-TCDD toxic equivalent factors (TEFs): Support for the use of the in
vitro AHH induction assay. Chemosphere 1987; 16:791-802.
Sawaguchi T, Matsurhura M, Kubota K. Dopamine enhances the neuronal activity of spatial short-term
memory task in the primate prefrontal cortex. Neurosci. Res. 1988; 5:465-473.
Schantz SL, Levin ED, Bowman RE, Heironimus MP, Laughlin NK. Effects of perinatal PCB exposure
on discrimination-reversal learning in monkeys. Neurotoxicol. Teratol. 1989; 11:243-250.
Schantz SL, Levin ED, Bowman RE. Long-term neurobehavioral effects of perinatal polychlorinated
biphenyl (PCB) exposure in monkeys. Environ. Toxicol. Chem. 1991; 10:747-756.
-------
Richard F. Seegal
Seegal RF, Bush B, Shain W. Lightly chlorinated ortho-substituted PCB congeners decrease dopamine
in nonhuman primate brain and in tissue culture. Toxicol. Appl. Pharmacol. 1990; 106:136-144.
Seegal RF, Bush B, Brosch KO. Comparison of effects of Aroclors 1016 and 1260 on nonhuman
primate catecholamine function. Toxicology 1991; 66:145-163.
Seegal RF, Bush B, Brosch KO. Decreases in dopamine concentrations in adult non-human primate
brain persist following removal from polychlorinated biphenyls. Toxicology 1994; 86:71-87.
Shain W, Bush B, Seegal RF. Neurotoxicity of polychlorinated biphenyls: Structure-activity relationship
of individual congeners. Toxicol. Appl. Pharmacol. 1991; 111:33-42.
Tilson HA, Jacobson JL, Rogan WJ. Polychlorinated biphenyls and developing nervous system:
cross-species comparisons. Neurotoxicol. Teratol. 1990; 12:239-248.
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APPENDICES F-G
OBSERVERS AND OBSERVER MATERIALS
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APPENDIX F
FINAL OBSERVER LIST
F-l
-------
U.S. Environmental Protection Agency
TECHNICAL REVIEW WORKSHOP ON THE REFERENCE DOSE (RID)
FOR AROCLOR1016
Barcelo Washington Hotel
Washington, DC
May 24-25,1994
FINAL OBSERVER LIST
Donald Barnes
Staff Director
Science Advisory Board
U.S. Environmental Protection Agency
401 M Street, SW
Washington, DC 20460
202-260-4126
Fax: 202-260-9232
Deborah Barsotti
Exxon Biomedical Sciences, Inc.
Metflers Road (CN2350)
East Millstone, NJ 08875-2350
908-873-6349
Fax: 908-873-6009
Elise Ann Brown
Toxicologist
Food Safety and Inspection Service
U.S. Department of Agriculture
300 12th Street, SW - Room 602
Washington, DC 20250
202-205-0367
Fax: 202-205-0145
John Brown
Manager, Environmental Toxicology
Research and Development
General Electric Corporation
P.O. Box 8
Schenectady, NY 12301-0008
518-387-7987
Fax: 518-387-7611
John Cicmanec
Veterinary Medical Officer
U.S. Environmental Protection Agency
26 West Martin Luther King Drive (MS-190)
Cincinnati, OH 45268
513-569-7481
Fax: 513-569-7916
Michael Dourson
Chief, System Toxicants Assessment Branch
U.S. Environmental Protection Agency
26 West Martin Luther King Drive (MS-190)
Cincinnati, OH 45268
513-569-7533
Fax:513-569-7916
Stephen Hamilton
Manager, Environmental Science and
Technology
General Electric Corporation
3135 Easton Turnpike
Fairfield,CT 06431
203-373-3316
Fax: 203-373-3389
Terry Harvey
Director
Environmental Criteria and Assessment Office
U.S. Environmental Protection Agency
26 West Martin Luther King Drive
Cincinnati, OH 45268
513-569-7531
Fax:513-569-7475
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Krishan Khanna
Pharmacologist
U.S. Environmental Protection Agency
401 M Street, SW (4304)
Washington DC 20460
202-260-7588
Fax: 202-260-1036
Carole Kimmel
Senior Level Scientist
Reproductive and Developmental
Toxicology Branch
Office of Research and Development
U.S. Environmental Protection Agency
401 M Street, SW (8602)
Washington, DC 20460
202-260-7331
Fax: 202-260-8719
Gary Kimmel
Reproductive and Developmental
Toxicology Branch
Office of Research and Development
U.S. Environmental Protection Agency
401 M Street, SW (8602)
Washington, DC 20460
202-260-5978
Fax: 202-260-8719
Edward Ohanian
Chief, Human Risk Assessment Branch
Office of Water
U.S. Environmental Protection Agency
401 M Street, SW (4304)
Washington, DC 20460 ,
202-260-7571
Fax: 202-260-1036
Dorothy Patton
Executive Director
Risk Assessment Forum
U.S. Environmental Protection Agency
401 M Street, SW (8101)
Washington, DC 20460
202-260-6743
Fax:202-260-3955
Resha Putzrath
Principal
Step 5 Corporation
1101 17th Street, NW - Suite 501
Washington, DC 20036
202-429-8761
Fax: 202-429-8762 .,
Sara Thurin Rollin
Reporter
Chemical Regulation Reporter
The Bureau of National Affairs, Inc.
1231 25th Street, NW
Washington, DC 20037
202-452-4584
Fax:202-452-4150
Susan Schantz
Assistant Professor of Toxicology
Institute for Environmental Studies
University of Illinois at Urbana-Champaign
1101 West Peabody Drive
Urbana, IL 61801
217-333-6230
Fax: 217-333-8046
JaySilkworth
Staff Toxicologist
Research and Development
General Electric Corporation
P.O. Box 8
Schenectady, NY 12301-0008
518-387-5895
Fax: 518-387-7611
Clare Stine
Risk Assessment Forum
U.S. Environmental Protection Agency
401 M Street, SW (8101)
Washington, DC 20460
202-260-6743
Fax: 202-260-3955
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Kamala Tripathi
Toxicologist
Chemistry Division
Food Safety and Inspection Service
U.S. Department of Agriculture
300 12th Street, SW - Room 603
Cotton Annex Building
Washington, DC 20250
202-2054)230
Fax: 202-205-0145
William Wood
Associate Director
Risk Assessment Forum
U.S. Environmental Protection Agency
401M Street, SW (8101)
Washington, DC 20460
202-260-6743
Fax: 202-260-3955
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APPENDIX G
OBSERVER COMMENTS
G4
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The Composition of the PCB Residues in Aroclor 1016/1248-Dosed Rhesus Monkeys
as Indicated by Barsotti's Packed Column Gas Chromatograms
by John F. Brown, Jr.
General Electric Corporate Research and Development
P.O. Box 8, Schenectady, New York 12301-0008 (518) 387-7987
During the May 24, 1994 discussions of the U.S. EPA Technical Review
Workshop on the Reference Dose (RfD) for Aroclor 1016, members of the Review Panel
repeatedly raised questions regarding the interpretation and interpretability of the gas
chromatograms (GCs) published by Barsotti and Van Miller in 1984. Since I have done a
great deal of work in PCB GC data analysis and interpretation during the past decade, I
should like to address some of the questions raised, and also indicate what sort of
conclusions can be drawn from the available GC data.
1. Identification of PCB Congeners Giving Peaks Resolved on an SE-30 Packed
Column. Many different types of PCB compositions have now been characterized
by both low resolution packed column GC, which was in general use in the
1970's, and high resolution capillary GC, which has been increasingly used in
recent years. Comparisons between the two types of GCs show that for the
commercial PCB products (e.g., Aroclors), the observed packed column peaks
(generally identified by relative retention times (RRTs), relative to DDE=100)
usually represent envelopes of 2-6 individual PCB congener peaks, most of which
are resolvable on suitable capillary columns. This means that it is generally not
possible to assign a packed column Aroclor peak to an individual PCB congener.
However, the PCB residues in higher animals that have been dosed with the lower
Aroclors, such as 1016, 1242, 1248, or even 1254, have a greatly simplified
congeneric composition, owing to the metabolism and elimination of most of the
lower PCB congeners originally present. As a result, most of the packed column
GC peaks exhibited by animal tissue residues are given by single congeners, and
the remainder are mostly simple binary mixtures. The identities of the
metabolically-resistant congeners giving the more commonly observed SE-30
peaks from some or all of these Aroclors have been reported (Brown et al., 1989)
as follows:
SE-30 Major Minor
RRT Component (No.) Component (No.)
37 2,4,4' CB (28)
47 2,2',4,4' CB (47) 2,2',5,5' CB (52)a
70,70A*> 2,4,4',5 CB (74) 2,3',4,4' CB (66)*>
78 2,3,4,4' CB (60)
84 2,2',4,4',5 CB (99) 2,2',4,5,51 CB (101)a
98 2,2',3,4,4t CB (85) + DDE
125 2,3',4,4',5 CB (118)
146 2,3,3',4,4' CB (105) 2,2',4,4',5,5' CB (153)c
174 2,2',3,4,41,5' CB (138) 2,3,3',4',5,6 CB (163)
a. Observed only in lightly metabolized specimens.
b. PCB No. 66 often resolved from PCB No. 74 even on packed columns.
c. Resolved from PCB No. 105 on mixed phase (pesticide) packed columns,
although not on SE-30; generally a dominant rather than a minor,
component of Peak 146 in environmental samples.
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Generally speaking, the quantitation of the packed column peaks, e.g., by the
products of the peak area and peak response factor, as in the method of Webb and
McCall (1973), is not much less precise than that for capillary GC peaks. As a
result, even though Barsotti's analyses were done by a now-obsolete procedure,
there is no methodological basis for challenging either the magnitudes of the
various PCB peaks observed or the identities of their major components. The
Webb and McCall procedure used should have required the determination of the
amount of PCB associated with each individual packed column peak, and then
adding these numbers to determine the total PCB present. If the original records
still exist, they should contain listings for the levels of each individual peak.
2. Characterization of Operative Metabolic Systemfs) from Residual PCB Congener
Distribution. It will be noted from the above table that the residual PCB
congeners in a well-metabolized specimen consist almost entirely of congeners
with 4,4'-substitution. Within this group, however, important variations in
relative persistence can occur. This was first reported by Masuda et al. (1974),
who noted that in chloracne patients who had ingested rice oil (yusho)
contaminated with PCB-PCDF mixtures, packed column Peaks 37, 70, 78, and
125 were either missing or sharply reduced, and Peak 146 somewhat reduced as
well, whereas Peaks 84,98+DDE, and 174 were unaffected, giving a peculiar GC
pattern termed "Pattern A." This was later recognized to have resulted from the
increased metabolism of the mono-ortho PCB congeners (e.g., PCB Nos. 74,60,
118, and 105) by the PCDF-induced cytochrome P4501A isozymes operating in
addition to the cytochromes with P4502B-like selection patterns which are
responsible for most of the PCB metabolism seen in normal humans, mice, eels,
crabs, etc. (Brown et al., 1989; 1992). Neither humans who were occupationally
exposed to Aroclors 1016, 1242, and 1254 (Brown et al., 1989; 1991) nor mice
dosed with Aroclor 1254 (Anderson et al., 1991) have shown "Pattern A" tissue
residues; however, in rats dosed with Aroclors 1242 or 1254, which are known to
be good inducers of P4501A isozymes in that animal, Pattern A is strongly
developed (Brown et al., 1994). Since Aroclor 1248 is known to induce P4501A
activity in the closely related cynomolgus monkey (Iverson et al., 1982) one
would also expect to find Pattern A in the monkey PCBs as well. However, a
recent examination of the residues in rhesus monkeys that had been chronically
dosed with Aroclor 1254 (Mes et al., 1989; Arnold et al., 1990; Brown, Arnold,
Mes, and Bryce, 1994, manuscript in preparation) showed exactly the opposite
• pattern, i.e., a preferential loss of di-orr/zo-substituted congeners (and in an
unusual selection pattern at that) relative to the mono-ortho congeners. This
unusual metabolic process was apparently able to overcome any tendency for
preferential mono-ortho congener removal by P4501A, and leave tissue residues
dominated by mono-ortho 4,4'-substituted congeners, e.g., PCB Nos. 105, 118,
and 156 from Aroclor 1254. In the Barsotti monkeys, it may be noted that four of
the five major peaks, i.e., Peaks 37, 70, 125, and 146 are given by mono-ortho's.
Peak 47 is not, but it is also the peak that dwindles away after the cessation of
dosing (Barsotti and Van Miller, Figure 4). Thus, the particular set of
4,4'-substituted PCB congeners that remain in the Barsotti monkeys are those that
would be expected in view of those observed by both packed column and
capillary GC in 1254-dosed monkeys.
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3. Calculation of Relative Contributions of Aroclor 1016 and 1248 to the PCS
Residues in Barsotti's Monkeys. During the panel discussions on May 24,
Professor Hartung correctly pointed out that to determine the relative proportions
of Aroclors 1016 and 1248 administered to the Barsotti's monkeys from the
composition of the residual PCBs in the monkey tissue would require quite
elaborate pharmacodynamic calculations. I would also add that the clearance rate
constant data needed to perform such calculations, although now known for the
human, are not known for the monkey.
However, for purposes of estimating toxic effects, it is probably more important
to determine the relative contributions to retained body burden, rather than
administered dose, since it is the retained PCBs that determine the internal
exposure of the animal.
Figure 1 shows a capillary GC for the brain PCB residues remaining in a pig-
tailed macaque that had been dosed with Aroclor 1016, as reported by Seegal et
al. (1990). (I have been informed by Seegal's co-author, Dr. Brian Bush, that the
chromatograms for other tissues from these animals were virtually identical to the
one shown as Figure 1.) It will be noted that the Seegal monkey's chromatogram
shows individual congener peaks for 2,4,4' CB, corresponding to packed column
Peak 37; for 2,2',5,1,5I- and 2,4,2',4 CB, corresponding to the marginally
bifurcated packed column Peak 47; and some very small unlabelled peaks in the
region expected for packed column Peak 70. The relative sizes of the peaks
corresponding to packed column Peaks 37, 47, and 70 are approximately as they
are in the Aroclor 1016 standard (Barsotti and Van Miller, Figure 1). By contrast,
the packed column GCs of the PCBs in Barsotti monkeys (Figures 2, 3) show
additional strong peaks with RRTs 70,125, and 146, and weaker ones at RRT 174
and in the RRT range 78-100. The additional peaks seen are those of the
4,4l-substituted tetra-, penta- and hexachlorobiphenyls present in .Aroclor 1248 or
1254 (see above table) and in approximately the relative proportions expected
from the packed column chromatograms of Aroclor 1248 (Webb and McCall,
1973). This Aroclor 1248 reference GC also shows, however, that any
contribution of Aroclor 1248 to the total would have to include substantial
contributions to Peaks 37. and 47 as well as giving Peaks 78-98, 125, 146, 174,
and most of Peak 70.
In order to estimate the relative contributions of Aroclors 1016 and 1248 to the
Barsotti monkey GCs, I first focused on GCs (e.g., Barsotti Figure 4) where all of
the peaks appeared to be on scale, so that they could be seen in their entirety. I
then estimated the relative area of each peak in mm2 by multiplying its height by
its half-width. Lacking any data on individual peak response factors for the GC
instrument used, I assumed that the quantity of PCB in each peak was
proportional to peak area. Any resultant errors were, however, at least partly
cancelled by applying the same procedure to the peaks in the Aroclor standards. I
then calculated, by the method of successive approximations, the relative
contributions of Aroclor 1016 and 1248 to the observed GC, assuming that each
of the persistent peaks would appear in the GC in the same proportions as in the
original Aroclor. The results for the relatively highly metabolized (low Peak 47)
PCBs of Barsotti and Van miller's infant monkey 4 mo. after weaning (their
Figure 4) are given below:
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Peak Total Area Attrib. to Attrib. to
No. (mm2) Aro. 1016 Aro. 1248
37 102 55 47
47 6 2 4
70 106 8 98
78-98 18- — 18
125 49 — 49
146 29 -- 29
174 8 — 8
Total 318 65 253
(%) (100%) (20%) (80%)
The results indicated that about 80% of the tissue residues in the infant monkey
remaining after 4 mo. recovery came from Aroclor 1248 rather than 1016. A
similar calculation for the same infant monkey at the time of weaning from
Figure 3 was a bit more difficult because Peaks 37 and 70 were off-scale;
however, guesses as to their areas from their widths suggested an Aroclor 1248
contribution around 60%. One might be concerned, however, over the apparently
large size of Peak 70 in Figure 3, which suggests the possibility that it might be
coming from a non-PCB contaminant If, as an extreme case, one were to assume
that Peak 70 came entirely from a contaminant, Peaks 37 and 47 entirely from
Aroclor 1016, and Peaks 78-174 from metabolized Aroclor 1248 residues, the
contribution of such residues to total peak area in Figure 4 would be 49%, and to
those of Figure 3, 35%. In short, the range of estimated contributions of Aroclor
1248 to the observed monkey PCB GCs was 35-80%, with the smaller numbers
requiring an assumption of analytical error concerning the true levels of Peak 70.
Lest anyone miss the point that tissue residues hi at least some of the 1016-dosed
monkeys must have come largely from Aroclor 1248,1 attach a copy of an old
SE-30 packed column chromatogram of Aroclor 1248, as shown as Figure 6 in the
original Webb and McCall paper of 1973, which was cited by Barsotti and Van
Miller as the basis for their analytical procedure. This chromatogram shows the
metabolically-resistant Aroclor 1248 peaks at RRT 37, 47, 70, 125, and 146 hi
just about the same relative proportions as in the monkey of Barsotti's Figure 3,
whereas Seegal's monkey (Figure 1), which received only Aroclor 1016, showed
significant levels of only the congeners corresponding to packed column peaks 37
and 47. In short, Barsotti and Van Miller's published chromatograms are simply
incompatible with their statement that the PCB given to the animals Was
essentially Aroclor 1016.
4. Sources of the Higher PCBs. The source(s) of the Barsotti monkeys' PGBs of
Peaks 70-174 remain problematic. One identified contributor is the monkey
chow, which did indeed contain low levels of PGBs. However, the adipose PCB
level hi control monkey No. 33 was only 0.36 ppm, and the GC pattern (Barsotti
and Van Miller Figure 6) showed little Peak 70 and Peak 146 > Peak 125, which
was more suggestive of the metabolized residues of an Aroclor 1254-like PCB
composition than Aroclor 1248. Thus, neither the level nor pattern of the higher
PCB peaks (i.e., those in the RRT range 70-174) in the control monkey that got
the same chow as the test animals seem consistent with the hypothesis that the
chow was the major sources of the higher PCBs seen in the test animals. Instead,
we must conclude that either Aroclor 1248 was inadvertently mixed into the feed,
along with the Aroclor 1016 that was on test, or else that the monkeys in the 1016
test groups were inadvertently given some of the Aroclor 1248-dosed feed that
-------
was being given to other test groups at the site. In view of the facts that one of the
original three Aroclor 1016 test groups was found, according to Barsotti's thesis,
to have received substantial quantities of PBB, which was also on test at the same
time, the latter possibility requires very serious consideration, and suggests that
the U.S. EPA should make an examination of the animal feeding records, as well
as getting analyses on any residual samples of the feed used. The alternative
possibilities, namely, that the higher PCBs came from either the chow as
purchased or from an error in the selection of the Aroclor added to it in preparing
the feed, could be easily assessed by checking out the relative levels of Peaks 125
plus 146 in the monkeys of the various study groups.
If it becomes necessary to obtain new chromatograms of stored monkey tissues in
order to make this assessment, or to assess the possibility that much of the
Peak 70 arose from a non-PCB impurity that was not removed by the analytical
clean-up procedure used, General Electric would be willing to provide or support
the appropriate GC analyses, subject to U.S. EPA involvement and overview.
5. Toxicological Implications. The hyperpigmentation and neurobehavioral effects
observed in Barsotti's Aroclor 1016/1248-dosed monkeys were more
conspicuously seen in the 1248-dosed monkeys, and have been already attributed
to the presence of toxic congeners such as 2,4,5,3',4'-pentachlorobiphenyl (Levin,
Schantz, Bowman, 1988). Since these, and other, congeners with dioxin-like
activities are lacking in Aroclor 1016, we must conclude that the hyper-
pigmentation and neurobehavioral effects arose from the inadvertent presence of
Aroclor 1248, rather than from the Aroclor 1016 itself.
Whether the weakly dioxin-like activity of the higher PCBs present in the
1016-dosed monkeys could also explain the seemingly reduced birth weight is
still problematical. In the Canadian studies of 1254-dosed rhesus monkeys there
were extensive observations of dioxin-like effects on the fingernails, meibomian
glands, and reproductive success, but reportedly no birth weight depression.
However, in view of the uncertain comparability between the test groups and
controls, the reality of the association between Aroclor 1016 and birth weight
depression remains uncertain.
In summary, advances in the understanding of PCB metabolism and
chromatography that have occurred in recent years have significantly increased the
interpretability of the sort of gas chromatograms shown in the Barsotti and Van Miller
report of 1984. It is now apparent that the internal PCB exposures experienced by the
monkeys that were given Aroclor 1016 were roughly half derived from higher Aroclors
rather than 1016 itself, and that the unambiguous toxic effects seen were characteristic of
those higher Aroclors. Accordingly, it seems most inappropriate to be using any results
observed in this seriously flawed study as a basis for an official agency position on the
risks posed by Aroclor 1016.
References
Anderson, L.M., Fox, S.D., Dixon, D., Beebe, L.E., and Issaq, HJ. 1991. Environ.
Toxicol. Chem. 10,681-690.
Arnold, D.L., Mes, J., Bryce, R, Karpinski, K., Bickis, M.G., Zawindzka, Z.Z., and
Stapley, R.F. 1990. Fd. Chem. Toxicol. 18, 847-857.
-------
Barsotti, D.A. and Van Miller, J.P. 1984. Toxicology 30,31-44.
Brown, J.F. Jr., Lawton, R.W., Ross, M.R., Feingold, J., Wagner, R.E., and Hamilton,
S.B. 1989. Chemosphere 19, 829-834.
Brown, J.F. Jr., Lawton, R.W., Ross, M.R., and Feingold, J. 1991. Chemosphere 23,
1811-1815.
Brown, J.F. Jr. 1992. Marine Environ. Res. 34,261-266.
Brown, J.F. Jr., Hamilton, S.B. Mayes, B.A., and Moore, J.A. 1994. The Toxicologist
14,432.
Iverson, F., Truelove, J., and Hierlihy, S.L. 1982. Fd. Chem. Toxicol. 20,307-310.
Levin, E.D., Schantz, S.L., and Bowman, R.E. 1988. Arch. Toxicol. 62,267-273.
Masuda, Y., Kagawa, R., and Kuratsune, M. 1974. Bull. Environ. Contain. Toxicol. 11,
213-216.
Mes, J., Arnold, D.L., Bryce, F., Davies, D.J., and Karpinski, K. 1989. Arch. Environ.
Contam. Toxicol. 18, 858-865.
Seegal, R.F., Bush, B., and Shain, W. 1990. Toxicol. Appl. Pharmacol. 106,136-144.
Webb, R.G. and McCall, A.C. 1973. /. Chromatog. Sci. 11,366-373.
Atts.
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SEEGAL. BUSH. AND SHAIN
47
2.5.2-.51
2A2-.4-
15
90
TIME (min)
FIG. I. Glass capillary gas chromatogram of Aroclor 1016 congeners present in the caudate^of the nonhuman
primate, Macaco nemesirina. following exposure to 3.2 mg/(kg-day) Aroclor 1016 for 20 weeks.
o
o
-. a.
Fig. 2. Gas chromatographic tracing of a subcutaneous fat sample from monkey No. 79 after
receiving 1.0 ppm Aroclor 1016 in the diet for 18 weeks. The level of Aroclor 1016 on a whole
tissue basis was 2.27 ppm and 3.25 ppm on a lipid basis. (Attenuation = 8; Temperature = 200°C).
Fig. 3. Gas chromatographic tracing of a mesenteric fat sample taken from monkey No. 79's
infant AG81 (1.0 ppm Aroclor 1016 group) at the time of weaning. The level of Aroclor 1016 on a
whole tissue basis was 10.43 ppm and 31.31 ppm on a lipid basis. (Attenuation = 32;
Temperature = 200°C).
-------
1248
47
Figure 6. EC chromatogram of Aroclor 1248 chromatographed
on SE-30 with a Ni-63 detector operated in thfe DC mode.
The peak identification numbers correspond to the retention
time relative to p,p'-DDE=100.
1173.
4U.S. GOVERNMENT PRINTING OFFICE: 1995 - 650-006/00238
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