4%	United States
Environmental Protectio
m «Agency
EPA/690/R-14/002F
Final
3-4-2014
Provisional Peer-Reviewed Toxicity Values for
Azodicarbonamide
(CASRN 123-77-3)
Superfund Health Risk Technical Support Center
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268

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AUTHORS, CONTRIBUTORS, AND REVIEWERS
CHEMICAL MANAGER
Zhongyu (June) Yan, PhD
National Center for Environmental Assessment, Cincinnati, OH
CONTRIBUTOR
Q. Jay Zhao, PhD, MPH, DABT
National Center for Environmental Assessment, Cincinnati, OH
DRAFT DOCUMENT PREPARED BY
ICF International
9300 Lee Highway
Fairfax, VA 22031
PRIMARY INTERNAL REVIEWERS
Paul G. Reinhart, PhD, DABT
National Center for Environmental Assessment, Research Triangle Park, NC
Ghazi Dannan, PhD
National Center for Environmental Assessment, Washington, DC
This document was externally peer reviewed under contract to
Eastern Research Group, Inc.
110 Hartwell Avenue
Lexington, MA 02421-3136
Questions regarding the contents of this document may be directed to the U.S. EPA Office of
Research and Development's National Center for Environmental Assessment, Superfund Health
Risk Technical Support Center (513-569-7300).
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TABLE OF CONTENTS
COMMONLY USED ABBREVIATIONS	iii
BACKGROUND	1
DISCLAIMERS	1
QUESTIONS REGARDING PPRTVs	1
INTRODUCTION	2
REVIEW OF POTENTIALLY RELEVANT DATA (CANCER AND NONCANCER)	5
HUMAN STUDIES	13
Oral Exposures	13
Inhalation Exposures	13
ANIMAL STUDIES	18
Oral Exposures	18
Inhalation Exposures	23
OTHER DATA	25
Carcinogenicity	25
DERIVATION 01 PROVISIONAL VALUES	26
DERIVATION OF ORAL REFERENCE DOSES	27
Derivation of Subchronic Provisional RfD (Subchronic p-RfD)	27
Derivation of Chronic Provisional RfD (Chronic p-RfD)	30
DERIVATION OF INHALATION REFERENCE CONCENTRATIONS	32
Derivation of Subchronic Provisional RfC (Subchronic p-RfC)	32
Derivation of Chronic Provisional RfC (Chronic p-RfC)	34
CANCER WEIGHT-OF-EVIDENCE (WOE) DESCRIPTOR	35
DERIVATION OF PROVISIONAL CANCER POTENCY VALUES	36
APPENDIX A. PROVISIONAL SCREENING VALUES	37
APPENDIX B. DATA TABLES	38
APPENDIX C. BMD OUTPUTS	46
APPENDIX D. REFERENCES	47
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COMMONLY USED ABBREVIATIONS
BMC
benchmark concentration
BMCL
benchmark concentration lower confidence limit
BMD
benchmark dose
BMDL
benchmark dose lower confidence limit
HEC
human equivalent concentration
HED
human equivalent dose
IUR
inhalation unit risk
LOAEL
lowest-observed-adverse-effect level
LOAELadj
LOAEL adjusted to continuous exposure duration
LOAELhec
LOAEL adjusted for dosimetric differences across species to a human
NOAEL
no-ob served-adverse-effect level
NOAELadj
NOAEL adjusted to continuous exposure duration
NOAELhec
NOAEL adjusted for dosimetric differences across species to a human
NOEL
no-ob served-effect level
OSF
oral slope factor
p-IUR
provisional inhalation unit risk
POD
point of departure
p-OSF
provisional oral slope factor
p-RfC
provisional inhalation reference concentration
p-RfD
provisional oral reference dose
RfC
inhalation reference concentration
RfD
oral reference dose
UF
uncertainty factor
UFa
interspecies uncertainty factor
UFC
composite uncertainty factor
UFd
database uncertainty factor
UFh
intraspecies uncertainty factor
UFl
LOAEL-to-NOAEL uncertainty factor
UFS
subchronic-to-chronic uncertainty factor
WOE
weight of evidence
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PEER-REVIEWED PROVISIONAL TOXICITY VALUES FOR
AZODICARBONAMIDE (CASRN 123-77-3)
BACKGROUND
A Provisional Peer-Reviewed Toxicity Value (PPRTV) is defined as a toxicity value
derived for use in the Superfund Program. PPRTVs are derived after a review of the relevant
scientific literature using established Agency guidance on human health toxicity value
derivations. All PPRTV assessments receive internal review by a standing panel of National
Center for Environment Assessment (NCEA) scientists and an independent external peer review
by three scientific experts.
The purpose of this document is to provide support for the hazard and dose-response
assessment pertaining to chronic and subchronic exposures to substances of concern, to present
the major conclusions reached in the hazard identification and derivation of the PPRTVs, and to
characterize the overall confidence in these conclusions and toxicity values. It is not intended to
be a comprehensive treatise on the chemical or toxicological nature of this substance.
The PPRTV review process provides needed toxicity values in a quick turnaround
timeframe while maintaining scientific quality. PPRTV assessments are updated approximately
on a 5-year cycle for new data or methodologies that might impact the toxicity values or
characterization of potential for adverse human health effects and are revised as appropriate. It is
important to utilize the PPRTV database flittp://hhpprtv.ornl.gov) to obtain the current
information available. When a final Integrated Risk Information System (IRIS) assessment is
made publicly available on the Internet (www.epa.eov/iris). the respective PPRTVs are removed
from the database.
DISCLAIMERS
The PPRTV document provides toxicity values and information about the adverse effects
of the chemical and the evidence on which the value is based, including the strengths and
limitations of the data. All users are advised to review the information provided in this
document to ensure that the PPRTV used is appropriate for the types of exposures and
circumstances at the site in question and the risk management decision that would be supported
by the risk assessment.
Other U.S. Environmental Protection Agency (EPA) programs or external parties who
may choose to use PPRTVs are advised that Superfund resources will not generally be used to
respond to challenges, if any, of PPRTVs used in a context outside of the Superfund program.
QUESTIONS REGARDING PPRTVs
Questions regarding the contents and appropriate use of this PPRTV assessment should
be directed to the EPA Office of Research and Development's National Center for
Environmental Assessment, Superfund Health Risk Technical Support Center (513-569-7300).
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INTRODUCTION
Azodicarbonamide (ADA), CASRN 123-77-3, is used in the rubber and plastic industries
as a blowing agent in the expansion of several polymers including polyvinyl chloride,
polyolefins, and other natural or synthetic rubbers. The World Health Organization (WHO)
developed a Concise International Chemical Assessment Document (CICAD) for ADA (Cary et
al.. 1999). In that document, it was stated that at around 190-230°C, ADA decomposes into the
gases nitrogen, carbon monoxide, carbon dioxide, and ammonia; solid residues; and sublimated
substances. The U.S. Food and Drug Administration permits the use of ADA as an aging and
bleaching ingredient in cereal flour and as a dough conditioner in bread making, provided that
the total amounts of ADA do not exceed 2.05 g per 100 pounds of flour (0.0045% or 45 ppm)
(NLM. 2011). ADA is poorly soluble in water and has a low vapor pressure, suggesting that it
has low volatility. A table of physicochemical properties for ADA is provided below (see
Table 1).
Figure 1. Chemical Structure of ADA (CASRN 123-77-3)
Table 1. Physicochemical Properties of ADA (CASRN 123-77-3)8
Property (unit)
Value
Boiling point (°C)
ND
Melting point (°C)
225
Density (g/cm3 at 20°C)
1.65
Vapor pressure (lmnHg at 20°C)
1.88 x 10"10
pH (unitless)
ND
Solubility in water (mg/L at 20°C)
35
Relative vapor density (air = 1)
ND
Molecular weight (g/mol)
116.08
aSource: NLM (2011).
ND = no data.
According to the WHO (Cary et al.. 1999). both inhaled and ingested ADA are rapidly
and completely converted to biurea (hydradicarbonamide, or HAD A), the only breakdown
product for ADA that has been identified. The WHO concluded that "it is likely that systemic
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exposure is principally to this derivative rather than to the parent compound" (Gary et at.. 1999).
Because ADA is rapidly and completely converted to HADA (Gary et al.. 1999). conversion of
ADA to HADA is assumed to occur at a 1:1 ratio. In this PPRTV assessment, molecular weight
adjustments were made in cases where dosimetry conversions from administered HADA to ADA
were necessary.
There are a number of studies in the available literature on ADA that present strong
evidence that ADA is a respiratory sensitizer in occupationally exposed humans (Kim et al..
2004; Normand et al.. 1989; Whitehead et al.. 1987; Ahrenholz et al.. 1985; Male et al.. 1985;
Slovak. 1981; Ferris et al.. 1977). Two of these independent studies (Malo et al.. 1985; Slovak.
1981) confirm cases of occupational asthma, with late-phase but not immediate reactions
following exposure to ADA. A recent National Institutes of Health white paper listed several
authoritative groups such as the European Union Health and Safety Executive, the New Jersey
Department of Health and Senior Services, and the Association of Occupational and
Environmental Clinics that have classified ADA as a respiratory sensitizer or asthmagen (MM.
2011). However, the available animal studies do not provide supporting data for ADA-induced
asthma. Several of the human occupational studies measure levels of ADA in the atmosphere
-3
(ranging from 0.01-12 mg/m ), and these concentrations can be adjusted for continuous
exposure to derive a provisional reference concentration (p-RfC) in the absence of suitable
animal data. Because adequate human data are the most relevant for determining the health
effects of a substance to humans and should be used to establish reference values when available,
the occupational studies were used for derivation of the subchronic and chronic p-RfCs for ADA.
Human data have been used on multiple occasions to derive reference values in IRIS, including a
value for beryllium based on respiratory sensitization in exposed persons (U.S. EPA. 1998).
Table 2 provides a summary of available toxicity values for ADA from U.S. EPA and
other regulatory agencies or organizations.
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Table 2. Summary of Available Toxicity Values for ADA (CASRN 123-77-3)
Source/Parametera'b
Value
(Applicability)
Notes0
Reference
Date Accessed
Noncancer
ACGIH
NV
NA
ACGIH C2013^
NA
ATSDR
NV
NA
ATSDR C2013^
NA
Cal/EPA
NV
NA
Cal/EPA (2014a.
b>
l-28-2014d
NIOSH
NV
NA
NIOSH (2010)
NA
OSHA
NV
NA
OSHA (2011.
2006)
NA
IRIS
NV
NA
U.S. EPA
1-28-2014
Drinking Water
NV
NA
U.S. EPA (2012a)
NA
HEAST
NV
NA
U.S. EPA (2011a)
NA
CARA HEEP
NV
NA
U.S. EPA (1994a)
NA
WHO
NV
NA
WHO
1-28-2014
UK HSC/MEL
1 mg/m3
Based on occupationally-induced
asthma.
Carv et al. (1999)
NA
UK HSC/STEL
3 mg/m3
Based on occupationally-induced
asthma.
Carv et al. (1999)
NA
Cancer
HEAST/WOE
NV
NA
U.S. EPA (2011a)
NA
IRIS
NV
NA
U.S. EPA
1-28-2014
HEAST
NV
NA
U.S. EPA (2011a)
NA
IARC
NV
NA
IARC (2013)
NA
NTP
NV
NA
NTP (2011)
NA
Cal/EPA
NV
NA
Cal/EPA (2014b.
2011)
NA
aSources: ACGIH = American Conference of Governmental Industrial Hygienists; ATSDR = Agency for Toxic
Substances and Disease Registry; Cal/EPA = California Environmental Protection Agency; CARA = Chemical
Assessments and Related Activities; HEAST = Health Effects Assessment Summary Tables; HEEP = Health and
Environmental Effects Profile; IARC = International Agency for Research on Cancer; IRIS = Integrated Risk
Information System; NIOSH = National Institute for Occupational Safety and Health; NTP = National Toxicology
Program; OSHA = Occupational Safety and Health Administration; UK HSC = United Kingdom Health and Safety
Commission; WHO = World Health Organization.
bParameters: MEL = maximum exposure limit; STEL = short-term exposure limit.
Information might include details related to the principal study, critical effect, and POD. A discussion of
uncertainty and/or modifying factor(s) is not included because these may differ among agencies/organizations,
precluding comparison.
The Cal/EPA Office of Environmental Health Hazard Assessment (OEHHA) Toxicity Criteria Database
(http://oehlia.ca.gov/tcdb/index.asp') was also reviewed and found to contain no information on ADA.
NA = not applicable; NV = not available.
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Literature searches were conducted on sources published from 1900 through
January 2014, for studies relevant to the derivation of provisional toxicity values for ADA,
CASRN 123-77-3. The following databases were searched by chemical name, synonyms, or
CASRN: ACGIH, ANEUPL, AT SDR, BIOSIS, Cal/EPA, CCRIS, CDAT, ChemlDplus, CIS,
CRISP, DART, EMIC, EPIDEM, ETICBACK, FEDRIP, GENE-TOX, HAPAB, HERO, HMTC,
HSDB, I ARC, INCHEM IPCS, IP A, ITER, IUCLID, LactMed, NIOSH, NTIS, NTP, OSHA,
OPP/RED, PESTAB, PPBIB, PPRTV, PubMed (toxicology subset), RISKLINE, RTECS,
TOXLINE, TRI, U.S. EPA IRIS, U.S. EPA HEAST, U.S. EPA HEEP, U.S. EPA OW, and
U.S. EPA TSCATS/TSCATS2. The following databases were searched for relevant health
information: ACGIH, AT SDR, Cal/EPA, U.S. EPA IRIS, U.S. EPA HEAST, U.S. EPA HEEP,
U.S. EPA OW, U.S. EPA TSCATS/TSCATS2, NIOSH, NTP, OSHA, and RTECS.
REVIEW OF POTENTIALLY RELEVANT DATA
(CANCER AND NONCANCER)
Table 3 provides an overview of the relevant database for ADA and includes all
potentially relevant, repeated short-term-, subchronic-, and chronic-duration studies. Principal
studies are identified in bold. The phrase "statistical significance" used throughout the document
indicates a^-value of <0.05 unless otherwise noted.
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Table 3. Summary of Potentially Relevant Data for ADA (CASRN 123-77-3)
Category
Number of
Male/Female per
Dose Group, Strain,
Species, Study Type,
Study Duration
Dosimetry"
Critical Effects
NOAEL"
BMDL/
BMCLa
LOAEL'
Reference
(Comments)
Notesb
Human
1. Oral (mg/kg-d)a
Acute0
ND
Short-termd
ND
Long-term"
ND
Chronicf
ND
2. Inhalation (mg/m3)a
Acute0
ND
Short-termd
ND
Long-term0
1/0, inhalation,
occupational
exposure, >10 yr
NV
Positive 1% ADA patch test;
subject was diagnosed with
ADA-induced occupational
asthma
NV
DU
NV
Kim et al.
(2004)
PR
4/0, inhalation and/or
dermal, occupational
exposure >3 yr
NV
Shortness of breath; asthma
attacks (at work or after
provocation tests) or asthmatic
bronchitis; decrements in 1-sec
forced expiratory volume
(FEVi); eczema of the hands,
forearms, or face
NV
DU
NV
Normand et al.
(1989)
PR
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Table 3. Summary of Potentially Relevant Data for ADA (CASRN 123-77-3)
Category
Number of
Male/Female per
Dose Group, Strain,
Species, Study Type,
Study Duration
Dosimetry"
Critical Effects
NO A EL"
BMDL/
BMCLa
LOAEL'
Reference
(Comments)
Notesb
Long-term"
2/0, inhalation,
occupational
exposure, >3 yr
NV
Both cases: irritation of the
eyes, cough, dyspnea,
shortness of breath, and
wheezing; decrements in FEVi
(24% decrease 6 hr after
exposure); case 1 diagnosed
with late-onset asthma, case 2
with both immediate- and late-
onset asthma reaction.
NV
DU
NV
Malo et al.
(1985); results
mirror effects in
Whitehead et al.
(1987) and
Slovak (1981)
PR
13/0, inhalation
and/or dermal,
occupational
exposure; spirometry
and exposure
measurements taken
on Monday, Friday,
and the following
Monday of a single
wk; total exposure
history unknown
Full-shift respirable
mass concentrations
were 0.25-0.75 on
Mondays and 0.68 on
Friday (adjusted from
time weighted-average)
6 workers had no complaints; 7
had symptoms: 6 had
productive cough, 5 had
shortness of breath, 5 had
nocturnal cough, 2 felt fatigued
at the end of the work day, and
2 had leg cramps; decreases in
FEVi and mean forced vital
capacity (FVC) were reported
between Monday and Friday
with some recovery the
following Monday after the
weekend with no exposure
NV
DU
0.25-0.75
(adjusted)
Ferris et al.
PR
(1977)
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Table 3. Summary of Potentially Relevant Data for ADA (CASRN 123-77-3)
Category
Number of
Male/Female per
Dose Group, Strain,
Species, Study Type,
Study Duration
Dosimetry"
Critical Effects
NO A EL"
BMDL/
BMCLa
LOAEL'
Reference
(Comments)
Notesb
Long-term"
151 (sex not
provided), inhalation,
occupational
exposure (duration
unknown)
0.7-1.8 (adjusted from
time weighted average)
18.5% (n = 28) of male
subjects diagnosed with asthma
after exposure; re-exposure
caused worsening of
symptoms; 7/13 sensitized
participants still exposed 3 mo
after onset of disease
developed prolonged airway
hyperreactivity to common
irritants
NDr
DU
0.7-1.8
(adjusted)
Slovak (1981)
PR
227 (80/147),
inhalation,
occupational
exposure, average
employment
duration >2.9 yr
Personal sampling
ranged from trace
(i.e., above detection
limit, but below the
quantifiable level) to
0.269 (mean of
0.00689) (adjusted
from time-weighted
average)
Lower respiratory effects and
symptoms of chronic
bronchitis correlated with
work involving ADA
supported by 17 workers
given pre- and
postpulmonary function tests
exhibiting statistically
significant, modest decreases
in FVC and FEV, during
work shift
NDr
DU
0.00689
(adjusted
mean,1984
sampling)
Whitehead et
al. (1987):
NIOSH (1985)
PS, PR
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Table 3. Summary of Potentially Relevant Data for ADA (CASRN 123-77-3)
Category
Number of
Male/Female per
Dose Group, Strain,
Species, Study Type,
Study Duration
Dosimetry"
Critical Effects
NO A EL"
BMDL/
BMCLa
LOAEL'
Reference
(Comments)
Notesb
Long-term"
30 exposed/16
unexposed (sex not
provided), inhalation,
occupational
exposure, average
employment of
6.25 yr
0.054-4.3 (mean: 1.3)
in those directly
exposed and
nondetectable to 0.036
in those indirectly
exposed (mean: 0.0036)
(adjusted from
time-weighted
average)
Increased (18/30, [60%]) lower
respiratory tract symptoms
(coughing, wheezing, and
shortness of breath) compared
with 1/16 (6%) unexposed
workers; increased (26/30,
[87%]) upper respiratory tract
symptoms (nasal stuffiness,
itchy or irritated eyes, and
runny nose) compared with
5/16 (31%) unexposed workers
NDr
DU
0.0036-1.3,
(adjusted
mean,
indirect and
direct
exposure)
Alirenliolz et al.
(1985)
NPR
Chronicf
ND
Animal
1. Oral (mg/kg-d)a
Subchronic
10/10, strain not
reported, mouse,
gavage, 5 d/wk,
13 wk
M: 0.7, 56, 111,223,
446, or 893
F: 0, 111,223,446, 893,
or 1,786
(adjusted)
No observed effects
893 (adjusted)
DU
NDr
IRDC (1982a)
in Carv et al.
(1999); original
study
unpublished and
unavailable
NPR
10/10, strain not
reported, rat, gavage,
5 d/wk, 13 wk
M: 0.7, 71, 357, or
1,786
F: 0, 143,714, or 3,571
(adjusted)
Mortality and pyelonephritis
with casts and crystalline
deposits in renal tubules in
males and females at 1,786 and
3,571 mg/kg-d, respectively
357 (adjusted)
DU
1,786 (FEL;
adjusted)
IRDC (1982b)
in Carv et al.
(1999); original
study
unpublished and
unavailable
NPR
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Table 3. Summary of Potentially Relevant Data for ADA (CASRN 123-77-3)
Category
Number of
Male/Female per
Dose Group, Strain,
Species, Study Type,
Study Duration
Dosimetry"
Critical Effects
NO A EL"
BMDL/
BMCLa
LOAEL'
Reference
(Comments)
Notesb
Subchronic
11-12/0 (12 in
control group and
11 in treatment
group), Sprague-
Dawley rat, diet,
4 wk
0, or 8,600 (adjusted)
Significantly decreased 24-hr
thyroidal 125I uptake
NDr
DU
8,600
(adjusted)
Gafford et al.
(1971)
PR
Chronic
25/25 (F0
generation), albino
FDRL rat, diet, 2 yr8
M: 0, 53.3, 168.5, or
533.1
F: 0, 60.5, 191.1, or
604.7
(adjusted)
M: 0,7
F: 0, 8.20
(adjusted)
No observed effects
533.1
(adjusted)
DU
NDr
Oser et al.
PR
This chronic
study is part
of the
reproductive
study
(1965a)
25/25 (10/10 in
control group), albino
FDRL rat, diet, 1 yrg
M: 0, 3,554, or 7,108
F: 0, 4,035, or 8,063
(adjusted)
No observed effects
7,108
(adjusted)
DU
NV
Oser et al.
CI965b)
PR
2/2, mongrel dog,
diet, 2 yrg
M: 0, 15.33,48.44, or
153.3
F: 0, 13.65,43.14, or
136.5 (adjusted)
No observed effects
136.5
(adjusted)
DU
NV
Oser et al.
CI965c)
PR
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Table 3. Summary of Potentially Relevant Data for ADA (CASRN 123-77-3)
Category
Number of
Male/Female per
Dose Group, Strain,
Species, Study Type,
Study Duration
Dosimetry"
Critical Effects
NO A EL"
BMDL/
BMCLa
LOAEL'
Reference
(Comments)
Notesb
Chronic
2/2, mongrel dog,
diet, 1 yrg
M: 1,022 or 2,044
F: 910 or 1,820
(adjusted)
Most of the treated dogs
became moribund; multiple
renal calculi, bladder calculi,
and chronic pyelonephritis
NDr
DU
NDr
Oser et al.
(1965d); frank
effects and lack
of control
prevent
establishment of
NOAEL/
LOAEL
PR
Developmental
ND
Reproductive
25/25 in F0
generation, 10/10 in
Fl, F2, and F3
generations, albino
FDRL rat, diet,
administered
HADA or ADA
M: 0,53.3,168.5, or
533.1
F: 0,60.5,191.1, or
604.7 (adjusted and
converted from HADA
to ADA dose) or M: 0,
7 F: 0,8.20 (adjusted
ADA dose)
No observed effects
Systemic:
533.1
(adjusted)
Reproductive:
604.7
(adjusted)
DU
NDr
Oser et al.
(1965e)
PS, PR
Carcinogenicity
ND
2. Inhalation (mg/m3)a
Subchronic
10/10, F344 rat,
inhalation, 6 hr/d,
5 d/wk, 13 wk
M: 0, 29.7, 60.6, or 121
F: 0, 30.6, 62.7, or 125
(adjusted,
extrarespiratory RDDR
used for all
concentration groups)
T3 and T4 levels in the highest
male exposure group
significantly elevated (50% and
40%, respectively) compared
with controls
60.6
DU
121
Medinskv et al.
(1990)
PR
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Table 3. Summary of Potentially Relevant Data for ADA (CASRN 123-77-3)
Category
Number of
Male/Female per
Dose Group, Strain,
Species, Study Type,
Study Duration
Dosimetry"
Critical Effects
NO A EL"
BMDL/
BMCLa
LOAEL3
Reference
(Comments)
Notesb
Subchronic
10/10, B6C3FJ
mouse, inhalation,
6 hr/d, 5 d/wk, 13 wk
M: 0, 49.9, 99.4 or 202
F: 0, 47.9, 96.3 or 196
(adjusted;
extrarespiratory RDDR
used for all
concentration groups)
No observed effects
196
DU
NDr
Medinskv et al.
(1990)
PR
10/0, Hartley guinea
pig, inhalation,
6 hr/d, 5 d/wk, 4 wk
0, 14.4, or 52.8
(adjusted;
extrarespiratory
RDDR used for all
concentration groups)
No observed effects
52.8
DU
NDr
Gerlacli et al.
(1989)
PR
Chronic
ND
Developmental
ND
Reproductive
ND
Carcinogenicity
ND
dosimetry: For animal studies, LOAEL, BMDL/BMCL, and LOAEL values are converted to an adjusted daily dose (ADD in mg/kg-d) for oral noncancer effects and a
human equivalent concentration (HEC in mg/m3) for inhalation noncancer effects unless otherwise noted. All long-term exposure values (4 wk and longer) are converted
from a discontinuous to a continuous exposure. Values from animal developmental studies are not adjusted to a continuous exposure.
RDDR = Regional Deposited Dose Ratio.
bNotes: IRIS = utilized by IRIS, date of last update; PS = principal study; PR = peer reviewed; NPR = not peer reviewed; NA = not applicable.
cAcute = exposure for <24 hr (U.S. EPA. 20021.
''Short-term = repeated exposure for >24 hr <30 d (U.S. EPA. 2002).
"Long-term = repeated exposure for >30 d <10% lifespan (based on 70-yr typical lifespan) (U.S. EPA. 2002).
'Chronic = repeated exposure for >10% lifespan (U.S. EPA. 2002).
8= studies were conducted by treating animals with HADA (all the doses in this table have been converted from HADA to ADA).
DU = data unsuitable; DUB = data unamenable to BMDS; NA = not applicable; NV = not available; ND = no data; NDr = not determined; NI = not identified; NP = not
provided; NR = not reported; NR/Dr = not reported but determined from data; NS = not selected.
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HUMAN STUDIES
Oral Exposures
The effects of oral exposure to ADA have not been evaluated in humans.
Inhalation Exposures
The effects of inhalation exposure of humans to ADA have been evaluated in seven
long-term-duration studies (Kim et al.. 2004; Norm and et at.. 1989; Whitehead et al.. 1987;
Ahrenholz et al.. 1985; Male et al. 1985; Slovak. 1981; Ferris et al. 1977). Due to a small
sample size, lack of proper controls, and/or lack of dosimetry information in the studies
conducted by Kim et al. (2004). Normand et al. (1989). Malo et al. (1985). and Ferris et al.
(1977). only three studies (Whitehead et al.. 1987; Ahrenholz et al. 1985; Slovak. 1981) were
considered as potential principal studies and are summarized in this document.
Acute
No acute inhalation studies in humans were identified.
Long-term Studies
Slovak (1981)
Slovak (1981) published a peer-reviewed occupational study of 151 employees (sex of all
employees not provided) that had been or were currently engaged in manufacture, servicing, and
quality control at an ADA plant since it opened in 1966. Slovak (1981) reported that because
ADA had a low acute toxicity, the plant was not designed to appropriately contain and ventilate
air contamination. Dust levels were measured following "standard techniques of industrial
hygiene with personal sampling by Casella pump followed by gravimetric analysis."
Time-weighted average concentrations of 2-5 mg/m3 ADA were reported; however, no
individual, raw exposure data were available. Adjusting for continuous exposure (from
5 working days to a full week) and minute volume, this range is 0.7-1.8 mg/m3. No data were
available for historical measured concentrations. An objective, nurse-administered questionnaire
and a structured, clinical occupational history collected by the study author were used to
determine any medical history of asthma. Workers exposed to ADA with a history of repeated
episodes of wheezing or chest tightness with or without cough were considered to have asthma.
Prick tests were also conducted in asymptomatic and ADA-sensitized exposed workers using 0.1,
1.0, or 5.0% ADA dissolved in dimethylsulfoxide. Spirometry was conducted before and after
shifts for three groups of workers: (1) workers diagnosed with ADA-induced asthma, (2) all
asymptomatic workers employed for at least 1 year in the plant, and (3) control process workers
without any contact to ADA or other lung sensitizers. Eleven workers with ADA-induced
asthma were provided with Wright mini-peak flow meters to self-record readings every 2 hours
during waking hours. Challenge tests were not conducted because such tests were not
considered justified in the occupational setting. It does not appear that study authors used
statistical methods to measure differences (and there were no unexposed workers to use as a
reference population for comparison) although the age and smoking habits of participants with
asthma were reported for the workers included in the study.
Twenty-eight men of 151 (18.5%) participants were diagnosed as having developed
asthma following exposure to ADA. Among these 28 male participants, more than 50%
developed asthma within 3 months of the initial exposure, and 75% developed it within the first
year. Furthermore, 56% had late-onset asthma, 22% had immediate-onset asthma, and 22% had
dual-onset asthma. Approximately 46% (13 participants) reported worsening symptoms and a
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shorter time between exposure at the plant and the reappearance of symptoms over the course of
their ongoing exposure. Based on medical notes taken during past asthma attacks, 12 out of
28 participants that experienced episodes of asthma were confirmed to have had asthma attacks
as a result of ADA exposure. About 44% of the participants reported their condition to the
occupational health department and were transferred to other work. Of the 13 participants that
continued working for more than 3 months, 7 developed subjective airway hyperactivity that
persisted for more than 1 month after cessation of exposure. Of these, 5 of the 8 male
participants exhibited persistent hyperactivity to general irritants such as sulfur dioxide and
tobacco smoke for over 3 years after removal from ADA exposure. The 28 participants whose
exposure ceased within the first 3 months did not exhibit persistent subjective airway
hyperactivity. Prick tests were negative for all concentrations in both asymptomatic and
ADA-sensitized exposed workers. Pre- and postshift spirometry readings were unremarkable
during the study; reversible airflow obstruction was not observed, and no asthma attacks were
observed. Peak flow measurements in sensitized individuals no longer exposed to ADA were
not different during holiday periods and times at work, confirming there was no occupational
exposure still affecting these individuals. Finally, atopy did not differ among ADA-sensitized
workers and unsensitized, asymptomatic workers who worked more than 1 year at the plant,
suggesting that atopy is not predictive of predisposition to ADA sensitivity.
Based on the development of asthma following exposure to ADA and the fact that
subjective airway hyperactivity persisted for at least 1 month following exposures of more than
3 months, Slovak (1981) concluded that ADA is a respiratory sensitizer. A LOAEL of
0.7-1.8 mg/m3 is established based on the respiratory symptoms reported in exposed workers;
the data preclude establishing a NOAEL. Although this study provides support that ADA is a
respiratory sensitizer, the subjects were exposed to a much higher concentration of ADA than the
Whitehead et al. (1987) study (0.00689 mg/m3) which is discussed below.
Whiteheadet al. (1987) andNIOSH (1985)
Whitehead et al. (1987) is selected as the principal study for the derivation of the
subchronic and chronic p-RfCs. In this occupational cross-sectional study, the study authors
evaluated a population of 227 employees (80 men and 147 women) at the Leon Plastics plant in
Grand Rapids, Michigan. The plant performed injection molding of a polyphenylene oxide resin
with ADA as a foaming agent. However, due to changes in plant operations, the use of ADA
decreased dramatically in the 4-5 months prior to this cross-sectional study. Current workers in
injection molding had worked at that job for an average of 3.1 years, compared to 2.9 years in all
other departments. The study authors administered pulmonary function tests (simple spirometry)
to 223 of the 227 workers, and pre- and postshift pulmonary function tests were administered to
17 workers currently working in injection molding to assess short-term pulmonary function
effects. Trained interviewers administered questionnaires that collected information on
occupational history (including departments worked at the Grand Rapids plant); smoking status;
past illness; and respiratory, nasal, eye, and skin symptoms. Pulmonary function values from
employees currently working in injection molding (currently exposed) were compared to those
from employees formerly working in injection molding (formerly exposed) and those of
employees who had never worked in injection molding (never exposed). With respect to the
prevalence of respiratory, nasal, eye, and skin symptoms, the following comparisons were made:
(1) employees currently working in injection molding were compared to employees currently
working in other departments, (2) employees formerly working in injection molding were
compared to employees formerly working in other departments, and (3) employees currently and
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formerly working in injection molding with known exposure to ADA were compared to
employees currently and formerly working in injection molding with no known exposure to
ADA. Logistic regression was used to analyze symptoms by presence or absence of exposure to
ADA as well as sex, age, pack-years smoked, current smoking status, and potential confounding
terms. A best model was found by backward elimination of nonsignificant terms using a
p-yalue <0.10 criterion of significance.
NIOSH (1985) conducted three surveys at Leon Plastics in Grand Rapids, Michigan.
However, in the initial survey conducted on March 24, 1983, exposures (personal and area) were
not measured. In the second and the third surveys conducted on May 2-6, 1983, and
March 11-12, 1984, respectively, NIOSH investigators gathered personal exposure information
and area concentrations of ADA, polyphenylene oxide (not an irritant), and thermal
decomposition products (i.e., styrene, benzene, phenol, xylene, and toluene). Samples were
analyzed using high-performance liquid chromatography (HPLC). During the May 1983 survey,
investigators detected benzene (0.02 mg/m3), styrene (0.09 mg/m3), toluene (1.5 mg/m3), xylene
3	3
(0.03 mg/m ), and phenol (0.5-1.9 mg/m ). In this survey, ADA concentrations of personal
samples ranged from nondetectable to 0.280 mg/m3 (reported as 280 |ig/m3) with a geometric
3	3
mean value of 0.0039 ± 0.0063 mg/m (reported as 3.9 ± 6.3 |ig/m ). Anecdotal interviews with
a focus on respiratory problems were conducted among 16 injection molding workers. In the
third survey in 1984, benzene was not detectable, styrene ranged from 0.1-0.3 ppm, and toluene
ranged from 0.03-0.1 ppm; xylene and phenol were not analyzed. Thirty-two personal sampling
results taken in the March 1984 survey, including 16 of the 17 workers given pre- and postshift
pulmonary function tests, showed that the concentration of ADA ranged from trace amounts
"3
(above the detection limit, but below the quantifiable level) to 0.752 mg/m (reported as
752 |ig/m3) with a geometric mean value of 0.0193 ± 0.0065 mg/m3 (reported as
-3
19.3 ± 6.5 |ig/m , cited from the study). It should be noted that all but 2 of the 32 samples fell
below 0.057 mg/m3. The two highest concentration values (0.368 and 0.752 mg/m3) occurred in
instances where a higher exposure would be expected—in one case, the worker's station was
located directly across from the resin mixing area; in the other case, the worker was a mixer of
ADA (NIOSH. 1985). After adjusting for continuous exposure (from 5 working days to the full
week) and minute volume, the exposure concentrations were ranged from trace to 0.269 mg/m3
"3
with a mean of 0.00689 mg/m (geometric mean; 1984 sampling). Table B. 1 provides the
1984 personal ADA sample results for the 32 workers. Whitehead et al. (1987) was an extended
analysis of the third survey from NIOSH (1985). The dosimetry data from March 1984 were
used for consideration of a study LOAEL because (1) the health study by Whitehead et al. (1987)
was conducted in conjunction with this March 1984 sampling period (and not during
1983 sampling), (2) the Whitehead et al. (1987) study has a relatively larger sample size and
complete health effect data, and (3) personal sampling from March 1984 provides a better
estimate of worker exposure levels.
The results from the Whitehead et al. (1987) study were summarized as follows. No
statistically significant differences in pulmonary function in the total population of workers were
observed when analyzed by departmental status (i.e., former-injection molding workers, current
injection molding workers, and never injection molding workers). However, modest, statistically
significant decrements in mean FVC and one-second FEVi over the work shift in the pre- and
postshift study of 17 injection mold operators were observed. No consistent dose-response
trends were observed in these 17 workers when stratified by measured ADA concentration level
3	3	3
(0-0.02 mg/m , 0.02-0.04 mg/m , or >0.04 mg/m ), years on current job, or the product of both
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measures (concentration x years on job). The respiratory symptoms reported in workers
currently working in injection molding were significantly more prevalent compared with workers
in all other departments. For current injection molding workers, the study authors reported
increased incidences of irritation (burning of the eyes, nose, or throat at least once per month;
odds ratio [OR]: \.ll,p = 0.04), coughing (OR: 1.98,p = 0.02), wheezing (OR: 2.75,p = 0.004),
and headache (OR: 1.82,/? = 0.04) (no confidence intervals for odds ratios were reported, see
Table B.2). The logistic regression analysis of these data yielded even more significant results
when results were adjusted for age, sex, pack-years smoked, and smoking status. In this case,
the study authors reported increased incidences of coughing (OR: 2.61 ,p = 0.002), wheezing
(OR: 3.86, p < 0.001), and headache (OR: 2.62, p < 0.001). The comparison of symptoms
between employees formerly working in injection molding and employees formerly working in
other departments also indicated significantly increased incidences of irritation, coughing,
shortness of breath, and headache (see Table B.2). Similarly, the comparison between
employees currently and formerly working in injection molding with known exposure to ADA
and employees currently and formerly working in injection molding with no known exposure to
ADA showed significant differences in the exposed employees that included increased
incidences of wheezing associated with shortness of breath (based on symptoms established from
American Thoracic Society guidelines; OR: 7.8,p = 0.01), chronic bronchitis (OR: 3.47,
p = 0.02), wheezing (based on symptoms reported by workers; OR: 16.32, p = 0.0001), and chest
tightness (OR: 6.72,p = 0.02) (see Table B.3).
The study authors concluded that there was "convincing evidence" that work in injection
molding was associated with respiratory symptoms including irritation, coughing, and wheezing;
however, the prevalence did not appear to be associated with the amount of time on the current
job (an average of 3.1 years in injection mold workers compared with 2.9 years in other
departments). The NIOSH report concludes that based on the exposure data and the study,
exposure to ADA is "considered the probable cause for the reported symptoms" (NIOSH, 1985).
One factor obscuring the relationship between ADA and health effects was the presence of other
contaminants. However, Whitehead et al. (1987) stated that polyphenylene oxide would not be
an irritant, and the thermal decomposition products were all measured at relatively low levels
(<0.1 mg/m3). Based on the increase in respiratory symptoms in injection molding workers, the
"3
geometric mean exposure concentration of 0.00689 mg/m is considered a LOAEL. The data
preclude establishing a NOAEL.
Ahrenholz et al. (1985)
In a NIOSH Health Hazard Evaluation Report, Ahrenholz et al. (1985) conducted an
occupational survey of exposure and symptoms in a group of workers (sex not provided) at the
Armstrong World Industries Floor plant in Lancaster, Pennsylvania. The plant manufactured
resilient flooring and officially began using ADA powder as a raw material in production during
1970. The initial NIOSH survey took place over November 30 and December 1, 1983, with an
in-depth, follow-up study completed January 8-11, 1984. In 1984, the study authors collected
ADA personal air concentrations using battery-operated sampling pumps for both full-shift and
short-term sampling. Exposure measures were collected from three groups: a directly exposed
group (working directly with ADA over a short period of time), an indirectly exposed group
(working in the vicinity where ADA was used), and an unexposed group (no expected exposure
for full-shift). A total of 30 ever-exposed (indirectly or directly) workers were included in the
study. Sixteen unexposed workers out of 44 total unexposed interviewees (i.e., full-shift with no
expected exposure) were also assessed for exposure and health-related symptoms. The study
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authors reported that the average employment duration for ever-exposed and unexposed workers
was 6.25 years. Health was assessed using a health interview and lung function tests. In the
initial survey, NIOSH investigators conducted brief interviews with employees, reviewed their
medical records, and conducted a medical evaluation to assess whether any reported health
effects were associated with work in departments using ADA. The medical evaluation consisted
of an in-depth questionnaire interview; pre- and postshift auscultation of the chest (listening to
the chest with a stethoscope); pre- and postshift pulmonary function tests (i.e., spirometry
measures of FVC, FEVi, and average rate of flow over the middle two quarters of the effort
[FEF25-75]); and blood serum sampling to analyze antibodies for ADA. The pulmonary function
tests were conducted in 15 of the 30 ever-exposed workers and 11 of the 16 unexposed workers.
Interviews were structured questionnaires designed to collect information about occupational
history, smoking status, and symptoms associated with upper and lower respiratory disease and
hypersensitivity pneumonitis. Investigators considered symptoms to be ADA related if they
were temporally related to work and occurred at times when ADA was handled or in areas where
dry ADA was present.
Results of ADA monitoring indicated that direct, measured exposure values ranged from
3	3
0.15—12 nig/m (n = 8 samples) with a mean exposure level of 3.6 mg/m (Ahrenholz et al..
1985). Indirect exposure values ranged from nondetectable to 0.1 mg/m3 (n = 25 samples) with a
"3
mean of 0.01 mg/m (Ahrenholz et al.. 1985). Control exposure levels ranged between
nondetectable and "trace" with 9 out of 12 samples falling below the detection limit. The mean
control exposure level was 0.001 mg/m ( Ahrenholz et al.. 1985). After adjusting for continuous
exposure (from 5 working days to the full week) and minute volume, direct exposure values were
3	3
0.054-4.3 mg/m with a mean of 1.3 mg/m . Indirect adjusted exposures values were
nondetectable to 0.036 mg/m3 with a mean of 0.0036 mg/m3. See Table B.4 for individual
exposure measurements.
Lower respiratory tract symptoms were reported by 18/30 ever-exposed workers and
1/16 unexposed workers. The study authors reported that these symptoms, including coughing,
wheezing, or shortness of breath, were significantly increased in ever-exposed workers (direct
and indirect exposures combined) versus unexposed workers. The risk of lower respiratory tract
symptoms was significantly increased in ever-exposed workers (risk ratio [RR] = 10,
p < 0.0004). The risk of upper respiratory tract and eye symptoms, including nasal stuffiness,
itchy or irritated eyes, and runny nose, was also statistically significantly increased (RR = 2.8,
p < 0.0001) in ever-exposed workers compared with unexposed workers (symptoms reported by
26/30 ever-exposed workers and 5/16 unexposed workers). See Table B.5 for symptom
prevalence and risk values. No statistically or biologically significant differences in lung
function were observed, as measured by FEVi and FVC tests, between ever-exposed and
unexposed workers (15/30 ever-exposed workers and 11/16 unexposed workers). The study
authors noted that the increased duration of smoking in the unexposed group (mean duration of
smoking: 24 years in unexposed and 16 years in ever-exposed; mean pack-years: 27 years in
unexposed and 18 years in ever-exposed) may have contributed to the lack of decreased
pulmonary function in ever-exposed compared with unexposed workers. Serum samples did not
show positive ADA-specific IgE determinations, and IgG results were not positive in the usual
dilution of greater than 1:50. The study authors concluded that it is unclear whether the potential
sensitization produced by ADA would be mediated through an immune mechanism. The results
suggested that workplace inhalation exposure to ADA may lead to a variety of upper and lower
respiratory tract symptoms. Based on significantly increased symptoms in ever-exposed workers
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(18/30 and 26/30 for lower and upper respiratory tract symptoms, respectively) compared with
unexposed workers (1/16 and 5/16 for lower and upper respiratory tract symptoms, respectively),
a mean exposure concentration from the ever-exposed workers could be identified as a LOAEL.
However, the study authors combined the indirectly and directly exposed workers in a pooled
analysis of symptoms in 18 ever-exposed workers compared with 16 unexposed workers, which
resulted in a range of exposure concentrations between indirect and direct exposures
(0.0036-1.3 mg/m ). As a result, there is uncertainty in identifying the true exposure level in the
"3
ever-exposed group. Thus, a LOAEL presented as a range of 0.0036-1.3 mg/m is established
based on significantly increased respiratory tract symptoms; the data preclude establishing a
NOAEL.
Chronic-duration Studies
No chronic-duration inhalation studies were identified.
ANIMAL STUDIES
Oral Exposures
The effects of oral exposure of animals to ADA have been evaluated in three
subchronic-duration studies (IRDC. 1982a. b; GatTord et al.. 1971). four chronic-duration studies
which includes initial 2-year and follow-up 1 -year studies in both rats and dogs (Oser et at..
1965a. b. c. d). and one reproductive toxicity study (Oser et al.. 1965e).
Subchronic-duration Studies
IRDC (1982a. b)
The original report of IRDC (1982a. b) was unpublished and unavailable for review.
Based on the information obtained from secondary sources by Carv et al. (1999). groups of
10 male mice (strain not reported) received 1, 78, 156, 312, 625, or 1,250 mg/kg-day (0.7, 56,
111, 223, 446, or 893 mg/kg-day, adjusted; it is not clear whether the male treatment lacked a
control group because no control dose is shown and the original study was not available), and
groups of 10 female mice (strain not reported) received 0, 156, 312, 625, 1,250, or
2,500 mg/kg-day (0, 111, 223, 446, 893, or 1,786 mg/kg-day, adjusted) by gavage, 5 days/week
for 13 weeks. No mortalities and no histopathological abnormalities were observed. Based on
no significant effects in this study, a NOAEL of 893 mg/kg-day was established. In another
study by IRDC (1982b). groups of 10 male rats (strain not reported) received 1, 100, 500, or
2,500 mg/kg-day (0.7, 71, 357, or 1,786 mg/kg-day, adjusted; it is not clear whether the male
treatment lacked a control group because no control dose is shown and the original study was not
available) and groups of 10 female rats (strain not reported) received 0, 200, 1,000, or
5,000 mg/kg-day (0, 143, 714, or 3,571 mg/kg-day, adjusted) by gavage, 5 days/week for
13 weeks. Mortality was observed at 1,786 mg/kg-day in males and at 3,571 mg/kg-day in
females. A histopathological study found pyelonephritis and crystalline deposits in renal tubules
in males at 1,786 mg/kg-day and in females at 3,571 mg/kg-day. Based on the observation of
mortality in males, a frank effect level (FEL) of 1,786 mg/kg-day was identified, with a NOAEL
of 357 mg/kg-day.
Gaffordet al. (1971)
In a published and peer-reviewed study bv(GatTord et al .. 1971). groups of male
Sprague-Dawley rats were administered a low iodine diet (Remington, General Biochemicals
Inc., Chagrin Falls, OH) with ADA (Aldrich Chemical Company, Inc., Cedar Knolls, NJ; purity
not reported) thoroughly blended in to produce diets of 0, 1, 5, or 10% ADA, or 5 or 10% HADA
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(the product when ADA is reduced). Another positive control group received a low iodine diet
containing 0.1% methimazole (MMI, a hyperthyroidism drug). The treatment duration varied by
experiment but was either 1 week (0, 1, or 10% ADA; 0.1% MMI positive control; 0 or
10% HAD A), 10 days (0 or 5% ADA; 0 or 5% HAD A), or 4 weeks (0 or 10% ADA). Only the
duration of the 4-week treatment qualifies as a candidate study for the derivation of a subchronic
reference dose; thus, only the results of this experiment are presented here. The 4-week study
included 11 male rats administered a 10% ADA diet and 12 male rats administered a control diet
(containing no ADA or MMI). The calculated adjusted daily doses are 0 and 8,600 mg/kg-day
based on a subchronic Sprague-Dawley male rat food intake factor of 0.086 kg/kg-day (U.S.
EPA. 1988). Animals were administered 0.1 microcurie ((.iCi) of1251 intraperitoneally 1 day
prior to the end of the experiment. At the end of the experiment, animals were sacrificed, and
thyroids were removed. Mean thyroidal 125I uptake, thyroid weight relative to 100 g body
weight, and total body weight were determined. The study authors measured 24-hour thyroidal
radioiodine uptake (it is assumed that the unit is percent) by counting thyroids and standards in
an automatic well counter. No histopathology evaluations were conducted. No details were
provided on the husbandry of the animals or the study's compliance with good laboratory
practice (GLP).
Table B.6 presents the results of 4-week dietary exposure to ADA as reported by GatTord
125
et al. (1971). Thyroidal I uptake was significantly decreased in animals receiving 10% ADA
in the diet (31.59 ± 8.37% compared with 42.42 ± 3.86% in controls;p < 0.001). Although this
effect was statistically significant, the study authors considered it a weak inhibitory effect that
was much smaller and less consistent than the inhibitory effect seen in positive controls given
MMI for 1 week. No statistically significant differences in relative thyroid weight (per 100 g
body weight) and mean body weight were observed compared to the control group. Because
only a single dose was examined in the subchronic-duration experiments, a NOAEL cannot be
identified. A LOAEL of 8,600 mg/kg-day is identified based on decreased 24-hour 125I uptake.
Although the magnitude of this effect was small in the present study, results suggest that thyroid
iodine uptake may be depressed at higher doses of ADA.
Chronic-duration Studies
Oser et al. (1965)
Oser et al. (1965) reports four experiments investigating the chronic oral toxicity of ADA
or HADA in both rats and dogs for 1- and 2-year durations. No effects were observed in the
initial testing conducted in rats and dogs for up to 2 years. In order to elicit toxicity and
determine potential target organs, higher doses were administrated in rats and dogs for 1 year in
a follow-up study. In this document, the Oser et al. (1965) study is divided into five separate
summaries including four chronic-duration studies (Oser et al .. 1965a. b. c. d) and one
reproductive toxicity studv(Oser et al.. l%5e; discussed in the Reproductive Studies section
below). These studies are peer-reviewed, but the study authors did not report whether the studies
were performed in compliance with GLP.
Oser et al. (1965a)
Oser et al. (1965a) conducted a 2-year study in albino rats (FDRL strain; source not
reported). This chronic-duration study is within a three-generation reproductive study in which
the F0 rats (25/sex/group) were dosed for up to 2 years. No effects were observed in these F0
rats at ADA doses up to 533.1 (males) and 604.7 (females) mg/kg-day. Based on the lack of
observed effects in any of the dose groups in this study, a NOAEL of 533.1 mg/kg-day is
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identified in males. To keep the study integrity and avoid redundancy, the study details are
presented in the Reproductive Studies section in Oser et al. (1965e).
Oser et al. (1965b)
In the follow-up study, Oser et al. (1965b) administered doses of 0, 5%, or 10% HADA
(purity and source not reported) to groups of 10/sex/group (controls) or 25/sex/group (treated)
weanling FDRL rats (source not reported) via diet made from flour for 1 year. At study
initiation, rats weighed 50-70 g. HADA was supplemented in a basal diet of Purina Laboratory
Chow; controls received an unmodified basal diet. All animals received extra vitamin
supplements in their food. Because body weight was only reported for 3 separate weeks
(Weeks 0, 12, and 52), study-specific data could not be used for dosimetry conversion. Using
U.S. EPA (1988) body weights and food consumption values, the adjusted ADA daily doses
(converted from HADA to ADA) are 0, 3,554, and 7,108 mg/kg-day in males and 0, 4,035, and
8,063 mg/kg-day in females.
Rats were examined daily, and body weights were recorded weekly; however, data were
not reported for each week. The efficiency of food utilization was calculated using food intake
data. At 12, 26, 44, and 52 weeks, blood was analyzed to determine hemoglobin, hematocrit,
total and differential leukocyte counts, glucose, and nonprotein nitrogen levels. Urine was tested
for albumin, sugar, and pH. Sediment in the urine was examined microscopically. Rats were
necropsied after death or terminal sacrifice at the end of the 1-year study period. At necropsy,
animals were examined for gross abnormalities and the liver, kidneys, spleen, heart, and adrenal
glands were weighed. Histopathological examinations were conducted for all visible
abnormalities as well as salivary, thyroid, and pituitary glands, liver, kidneys, spleen, pancreas,
adrenals, lungs, heart, gonads, stomach, large and small intestines, bladder, and lymph nodes.
The study authors reported no adverse behavioral effects or clinical signs in treated rats. All
animals survived the year with the exception of one male administered 7,108 mg/kg-day. No
treatment-related changes in body weight, organ weight, hematology, or histopathology were
observed. Based on the lack of observed effects in any of the dose groups in this study, a
NOAEL of 7,108 mg/kg-day is identified.
Oser et al. (1965c)
Oser et al. (1965c) also conducted a study where mongrel dogs (2/sex/dose group)
received diets of bread supplemented with 0, 750, 2,370, or 7,500 ppm of HADA for 2 years.
The adjusted ADA daily doses (converted from HADA to ADA) are 0, 15.33, 48.44, and
153.3 mg/kg-day in males and 0, 13.65, 43.14, and 136.5 mg/kg-day in females. Food intake
was recorded weekly for 12 weeks. Body weights were recorded weekly for 12 weeks and
monthly thereafter. At 3, 6, 12, 18, and 24 weeks, blood was analyzed for hemoglobin,
hematocrit, methemoglobin, total and differential leukocyte counts, glucose, and nonprotein
nitrogen. At the end of 2 years, each animal was sacrificed for necropsy. Organ weights were
recorded, and histopathological examinations were conducted on multiple organs including
salivary, thyroid, and pituitary glands, liver, kidneys, spleen, pancreas, adrenals, lungs, heart,
gonads, stomach, large and small intestines, bladder, and lymph nodes. Although this 2-year
study in mongrel dogs was limited by a small sample size, no observed effects were reported by
the study authors. Based on the absence of observed effects in treated dogs, a NOAEL of
136.5 mg/kg-day is identified.
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Oser et al. (I965d)
In the follow-up study, Oser et al. (1965d) administered doses of 5% or 10% HADA to
groups of mongrel dogs (2/sex/group) via diet for 1 year. Using U.S. EPA (1988) body weights
and food consumption values, the adjusted ADA daily doses (converted from HADA to ADA)
are 1,022 and 2,044 mg/kg-day in males and 910 and 1,820 mg/kg-day in females. No control
groups were reported. Food intake and body weights were recorded weekly for 12 weeks and
monthly thereafter. The food intake data were only reported up to the first 12-week period, and
body-weight data were only reported for 0, 12, and 24 weeks and at the terminal stage. At 12,
37, and 40 weeks, blood samples were analyzed to determine hemoglobin, hematocrit,
methemoglobin, total and differential leukocyte counts, glucose, and nonprotein nitrogen. All
dogs that died or became moribund and were sacrificed were examined grossly and
histopathologically. Organ weights were recorded and histopathological examinations were
conducted as in the 2-year dog study. Renal and bladder calculi recovered from the dogs at
autopsy were analyzed chemically for biurea. Initially, the dogs were reluctant to eat the diet,
but eventually, the food intake for the first 12-week period in the 5% HADA groups (average of
17.5 kg per dog) was comparable to the intake of the control dogs in the 2-year study (Oser et al ..
1965c). In most of the dogs, the body weight was fairly constant for the first half year; then
body weight in some dogs precipitously declined or the dogs died. The hemoglobin and
hematocrit values were normal. The total leukocyte counts were within normal limits, but the
counts from dogs that died before terminal sacrifice was not included. In the dogs receiving 5 or
10% HADA, the polymorphonuclear:lymphocyte ratio increased in the latter part of their lives.
Blood sugar levels were normal, but blood nonprotein nitrogen levels increased terminally in
most of the dogs. Weights of the liver, kidneys, spleen, heart, and adrenals were normal within
20-44 weeks. After 44 weeks, the study authors did not provide organ weight information. The
most significant gross finding in both the 5 and 10% HADA treatment groups was the presence
of massive, multiple, renal calculi which, in about half the cases, were accompanied by bladder
calculi. Analyses of calculi specimens indicated the principal constituent (comprising
approximately 80—100%) was HADA. The principal microscopic findings were secondary to the
local irritation of the stones (i.e., chronic pyelonephritis). Of organs and tissues that were
examined, no significant pathological changes were observed in the liver, adrenals, spleen,
bladder, pituitary, brain, and lung (pathology evaluations for other organs were not reported).
The authors concluded that the presence of chronic pyelonephritis and chronic pyelitis seen in
most of the dogs is a consequence of the deposition of the massive urinary and bladder calculi in
the dogs. Because this 1-year study lacked a control group and resulted in frank effects
(mortality) at high ADA doses (up to 2,044 mg/kg-day), the data preclude establishing a NOAEL
or a LOAEL.
Developmental Studies
No oral developmental toxicity studies were identified.
Reproductive Studies
Oser et al. (1965e)
A reproductive toxicity study by Oser et al. (1965e) was selected as the principal
study for the derivation of the subchronic and chronic p-RfDs. In a published,
peer-reviewed, three-generation study, Oser et al. (1965e) examined the reproductive and
developmental effects of ADA (purity and source not reported) or HADA (purity and source not
reported) fed to rats in their diet. Twenty-five female and 25 male weanling albino rats (FDRL
strain; source not reported) weighing 50-70 g received a diet made using flour containing 0- or
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100-ppni ADA, ad libitum. Using body weights and food consumption from U.S. EPA (1988).
the adjusted daily doses for the groups dosed with the parent compound (ADA) are 0 and
7 mg/kg-day for males and 0 and 8.20 mg/kg-day for females.
Additional groups of 25 female and 25 male weanling albino rats were fed diets of
untreated bread supplemented with 0, 750, 2,370, or 7,500 ppm of HADA. Body weight and
food consumption data available in the study report were limited and insufficient to use for
dosimetry calculations. However, using food intake and body weights for a chronic exposure
duration from U.S. EPA (1988)and adjusting for the difference in molecular weight between
ADA and HADA, doses are calculated as 0, 53.3, 168.5, and 533.1 mg/kg-day for males and 0,
60.5, 191.1, and 604.7 mg/kg-day for females.
All animals were housed individually, but environmental parameters (e.g., temperature,
humidity, and lighting) were not described. Mating procedures were not described; therefore, it
is unclear if sibling matings were avoided. F0 rats from both ADA and HADA treatment groups
received their respective diets for 2 years, during which time they delivered two litters,
designated Fla and Fib. Male and female rats (10/sex) from the second Fib litters were mated
to produce two litters of F2offspring (F2a and F2b). Male and female rats of the F2b generation
(10/sex) were also mated to produce F3 offspring (F3a and F3b) although the specific number of
animals mated was not reported. Rats were examined daily, and body weights were recorded
weekly; however, body-weight data were only reported for Weeks 0, 12, 52, and 104. For each
generation of rats, the efficiency of food utilization was calculated using food intake data
recorded during the first 12 weeks of the study. At 6 and 12 weeks (for rats from all generations)
and at 6 months (for rats from the F0, Fl, and F2 generations), blood was analyzed to determine
hemoglobin, hematocrit, total and differential leukocyte counts, glucose, and nonprotein nitrogen
levels. Urine was tested for albumin, sugar, and pH. Sediment in the urine was examined
microscopically. All rats were necropsied after death or terminal sacrifice at the end of the
2-year study period. At this time, F0 rats had completed 2 years on the test diets, whereas Fl and
F2 rats had completed 28 or more weeks, and F3 rats had completed 14 weeks.
At necropsy, all rats from each generation were examined for gross abnormalities, and
the liver, kidneys, spleen, heart, and adrenal glands were weighed. Histopathological
examinations were conducted in all rats for all visible abnormalities as well as the salivary,
thyroid, pituitary glands, the liver, kidneys, spleen, pancreas, adrenals, lungs, heart, gonads,
stomach, large and small intestines, bladder, and lymph nodes. Reproduction and lactational
parameters examined in F0, Fl, and F2 rats included the average number of pups per litter at
birth and weaning, the average weight of pups at 21 days, the fertility index, the gestation index,
the viability index, and the lactation index. Although the study authors included statements
regarding statistical difference in their conclusions, the statistical tests used to analyze the data
were not reported.
Compared with controls, no differences in survival, growth, food consumption,
hematology, or pathology (in F0, Fl, F2, and F3 rats) and reproduction and lactation (in F0, Fl,
and F2 rats) were observed in animals administered either the ADA or HADA diets. See
Table B.7 for a summary of reproduction and lactation outcomes. Although there appear to be
no consistent dose-related trends or generational trends, it should be noted that a number of the
indices may have been affected in a biologically significant manner (e.g., fertility index
[pregnancies ^ matings x 100] in the F0 generation at the highest dose, which was only 70%,
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one-third lower than the index for the control dams). A number of the control groups had low
indices, including fertility in the F0 generation (57% in controls) and viability in several groups
(68% in F0 controls, 62% in F1 controls, and 60% in F2 controls). The study authors stated that
the low fertility indices in F0 rats (control and treatment groups) were possibly due to an
environmental factor (i.e., moving of the laboratory). This study is also limited because it did
not examine all reproductive end points required in the Organisation for Economic Co-Operation
and Development (OECD) Guideline 416 or OPPTS 870.3800. Parental animals were weanlings
at dose initiation rather than the suggested 5 to 9 weeks old. Body weights were not reported for
gestation and lactation Days 0, 7, 14, and 20 or 21. The average weight of pups was only
reported at 21 days. Individual data were not available for pups or adult animals. The study
authors did not monitor female estrous cycles or male sperm parameters (sperm motility and
sperm morphology; total number of homogenization-resistant testicular spermatids and cauda
epididymal sperm). The study authors reported that the "gonads" (strictly defined as the ovaries
and testes) were weighed and examined; it is unclear whether the study authors also included the
uterus, epididymides (total and cauda), prostate, and seminal vesicles with coagulating glands
and their fluids. The number of resorptions and stillbirths were not reported. The study authors
provided no information on gross anomalies, age of vaginal opening and preputial separation, or
anogenital distance in pups, but stated that "all other parameters of reproduction and lactation,
including the number of pups born and weaned, as well as their growth and development, were
comparable among test and control groups". Despite the missing data, this reproductive study is
still considered acceptable. The study involved the treatment of a sufficient number of animals
(25/sex/group, yielding 50 matings in the F0 and 20 in the F1 and F2 generations) for up to
2 years. Based on the reproductive and lactation data provided, it appears that doses of up to
604.7 mg/kg-day ADA did not affect reproduction in FDRL rats. While male gonad weight was
unaffected, no other male parameters were directly measured by the study authors. Because the
female parameters are more comprehensive and closely related to pups, they are used for
identification of the reproductive NOAEL. In females, gonad weight, fertility index
(pregnancies/matings), gestation index, and lactation index were evaluated and unaffected by
treatment. Therefore, a reproductive NOAEL of 604.7 mg/kg-day is identified based on the lack
of effects in females at this dose (the highest tested). In addition, this dose of ADA did not cause
significant changes in hematology, histopathology, and organ/body weights in treated animals.
Based on the absence of effects in treated rats of either sex, a NOAEL of 533.1 mg/kg-day is
identified for systemic effects.
Inhalation Exposures
The effects of inhalation exposure of animals to ADA have been evaluated in three
subchronic-duration experiments within two studies (Medinskv et al.. 1990; Gerlach et al..
1989).
Medinskv et al. (1990)
In a published, peer-re viewed subchroni c-durati on study, Medinskv et al. (1990)
examined the toxic effects of ADA aerosol (98% purity) on F344 rats. Four-week-old F344 rats
were exposed by inhalation, 6 hours/day, 5 days per week for a total 13 weeks. In the basic
study group, 10 female and 10 male per concentration group were exposed to 0, 50, 100, or
-3
204 mg/m ADA aerosol with corresponding mass median aerodynamic diameters (MMADs) of
0, 2.33, 2.45, and 2.37 |im, respectively. Concentrations were adjusted for continuous exposure
and converted to a human equivalent concentration (HEC) using a regional deposited dose ratio
(RDDR) for particles; the HECs are 0, 29.7, 60.6, or 121 mg/m in males and 0, 30.6, 62.7, or
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-3
125 mg/m in females (based on the extrarespiratory RDDR). Mortality/morbidity was observed
twice daily. Histopathology, hematology, body weight, organ weight, sperm morphology, and
vaginal cytology were also evaluated. No mortality or clinical signs related to ADA exposure
were observed. Lung weights of male and female rats were increased (111% of control) only at
3	3
the 50-mg/m exposure level. In addition, males and females exposed to 50 mg/m ADA had
enlarged bronchial and mediastinal lymph nodes at gross necropsy. Histopathological
examination of these nodes suggested moderate-to-severe lymphoid hyperplasia. Both male and
female rats in the 50-mg/m3 exposure group showed lung lesions that consisted of perivascular
cuffing with lymphocytes and a multifocal type II cell hyperplasia that was associated with a
moderate number of mixed inflammatory cells. The study authors suggested a possible immune
reaction to an antigen in the lung. However, no exposure-related lesions were observed
microscopically in rats exposed to 100 or 204 mg/m3 ADA; therefore, the pulmonary effects
"3
observed at 50 mg/m may not be related to exposure. The study authors reported no
exposure-related alterations in blood parameters and no significant changes in the amounts of
examined urinary enzymes. Further, neither effects in right caudal weight, right epididymal
weight, right testicular weight, sperm motility, sperm account per gram caudal tissue, or
incidence of abnormal sperm nor apparent effects on estrual cyclicity or on estrous cycle length
were observed.
In second study group, 10 female and 10 male F344 rats were exposed to the same levels
of ADA as the basic study group mentioned above. Acetylcholinesterase activity in whole blood
and T3 and T4 levels in serum were determined at the end of this 13-week study. While no
significant difference in acetylcholinesterase activities was observed compared to controls, T3
and T4 levels were significantly increased approximately 50% and 40%, respectively, relative to
controls at the highest exposure level in male rats. Therefore, a NOAEL of 100 mg/m3
(HEC = 60.6 mg/m3) and a LOAEL of 204 mg/m3 (HEC = 121 mg/m3) were identified from the
Med in sky et al. (1990) study based on significantly increased T3 and T4 levels in the highest
male exposure group.
Med in sky et al. (1990) also conducted a 13-week inhalation study in B6C3Fi mice. The
experimental design (including number of animals, study duration, target concentrations, and
endpoints [including T3 and T4 measurements] examined) was the same as the 13-week F344 rat
study describe above. The mean terminal body weights in male mice were statistically
significantly depressed by 7% and 9% relative to controls at the 100-mg/m3 (HEC = 99.4 mg/m3)
3	3
and 204-mg/m (HEC = 202 mg/m ) exposure levels, respectively. For female mice, the terminal
body weights were statistically significantly decreased by 6% at the highest concentration
3	3
(204 mg/m ; HEC = 196 mg/m ). However, all these changes were less than 10% compared to
the control; therefore, the decreased body weight is not considered a biologically significant
effect. No additional effects were observed. Therefore, a NOAEL of 204 mg/m
(HEC =196 mg/m3; highest concentration tested) is identified (based on the extrarespiratory
RDDR). The data preclude establishing a LOAEL.
Gerlach et al. (1989)
In a peer-reviewed study by Gerlach et al. (1989). groups of male Hartley strain guinea
pigs were exposed by inhalation to aerosolized ADA at 0, 51, or 200 mg/m3, 6 hours/day,
"3
5 days/week for 4 consecutive weeks. The HECs are 0, 14.4, and 52.8 mg/m (based on the
extrarespiratory RDDR). One group (10 animals per concentration) was tested for specific
airway sensitization to ADA before and 3 days after the 4-week ADA exposure. The other group
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was tested for nonspecific airway sensitization by inhalation challenge with aerosolized
histamine before and after the 4-week ADA exposure. Body, lung, liver, kidney, and thymus
weights were recorded after sacrifice. A skin test for immunological response was also
conducted. Histopathological examination was performed in the nasal cavity, larynx, trachea,
lungs, tracheobronchial and popliteal lymph nodes, and skin test site. No significant effects were
reported. Due to a lack of effects at concentrations up to 200 mg/m3 (HEC = 52.8 mg/m3), a
3	3
NOAEL of 200 mg/m (HEC = 52.8 mg/m ) was identified (based on the extrarespiratory
RDDR) for this study.
OTHER DATA
Several studies examining the mutagenic and genotoxic potential of ADA were
identified. Data on the mutagenicity of ADA are mixed. In vitro studies have found that ADA is
mutagenic with and without metabolic activation in bacteria (Mortelmans et al.. 1986;
Pharmakon Research International. 1984a). However, in vitro assays in mammalian cell
systems, including gene mutation assays in Chinese hamster ovary cells and mouse lymphoma
cells, were negative (Pharmakon Research International. 1984b). In addition, a sex-linked
recessive lethal assay (Yoon et al. 1985) was negative for mutagenicity. Pharmakon Research
International (1984c) and (Hachiva. 1987) also completed intraperitoneal (i.p.) in vivo bone
marrow micronucleus assays in mice (0 or 150 mg/kg-day) which were negative for
genotoxicity. Another in vitro liver unscheduled DNA synthesis assay indicated that ADA is not
genotoxic (Pharmakon Research International. 1984d).
Carcinogenicity
No carcinogenicity studies were identified.
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DERIVATION OF PROVISIONAL VALUES
Tables 4 and 5 present summaries of noncancer and cancer reference values, respectively. IRIS information are indicated in the
tables, if available.
Table 4. Summary of Noncancer Reference Values for ADA (CASRN 123-77-3)
Toxicity Type (units)
Species/Sex
Critical Effect
p-Reference
Value
POD
Method
PODhed/hec
UFC
Principal Study
Subchronic p-RfD
(mg/kg-d)
Rat/M+F
No observed reproductive effects
1 x 10°
NOAF.I.
147.5
100
Oseret al. (1965eN)
reproductive study
Chronic p-RfD
(mg/kg-d)
Rat/M+F
No observed reproductive effects
1 x 10°
NOAF.I.
147.5
100
Oseret al. (1965e)
reproductive study
Subchronic p-RfC
(mg/m3)
Human/not
provided
Respiratory effects, supported by
decrements in lung function (FEV,
and FVC)
7 x 10"6
LOAEL
0.00689
1,000
Whitehead et al. C1987)
Chronic p-RfC
(mg/m3)
Human/not
provided
Respiratory effects, supported by
decrements in lung function (FEVi
and FVC)
7 x 10"6
LOAEL
0.00689
1,000
Whitehead et al. C1987)
Table 5. Summary of Cancer Values for ADA (CASRN 123-77-3)
Toxicity Type
Species/Sex
Tumor Type
Cancer Value
Principal Study
p-OSF
NDr
p-IUR
NDr
DU = data unsuitable; DUB = data unamenable to BMDS; NA = not applicable; NV = not available; ND = no data; NDr = not determined; NI = not identified;
NP = not provided; NR = not reported; NR/Dr = not reported but determined from data; NS = not selected.
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DERIVATION OF ORAL REFERENCE DOSES
Derivation of Subchronic Provisional RfD (Subchronic p-RfD)
The principal study selected for derivation of the chronic p-RfD is the reproductive
study by Oser et al. (1965e). The database for ADA oral toxicity includes three subchronic-
duration toxicity studies (1RDC. 1982a. b; Gafford et al.. 1971). four chronic-duration toxicity
studies (Oser et al, 1965a, b, c. d), and one reproductive toxicity study (Oser et al, 1965e).
Among the subchronic-duration studies, the IRDC study (1982a) in mice identified a NOAEL of
893 mg/kg-day based on no observed effects. The IRDC study (1982b) in rats reported an FEL
and renal effects at the highest dose of 1,786 mg/kg-day. The two IRDC studies (1982a, b),
however, were not considered principal study candidates because the original report was
unpublished and unavailable for review, and information could only be obtained from secondary
sources. The subchroni c-durati on rat study by GatTord et al. (1971) had a LOAEL of
125
8,600 mg/kg-day based on decreased thyroid I uptake. The 2-year dog chronic-duration study
had a NOAEL of 136.5 mg/kg-day based on no observed effects (Oser et al., 1965c). However,
the 1 -year and 2-year dog chronic-duration studies (Oser et al.. 1965c, d) are limited because
both studies were conducted with a very small sample size (2/sex/group) and the 1-year study
lacked a control group (Oser et al.. 1965d). Although the subchroni c-durati on study by Gafford
et al. (1971) showed potential thyroid effects as suggested by the decreased iodine uptake in rat
thyroid at a dose of 8,600 mg/kg-day, and the IRDC (1982b) study showed an FEL and kidney
effects in rats at the highest dose of 1,786 mg/kg-day, these observations were limited due to
limited endpoints examined (no histopatholoev evaluation in GatTord et al., 1971) or lack of
toxicity information (original study was not available for review for IRDC, 1982b). Compared
to the subchroni c-durati on studies, the 1- and 2-year rat chronic-duration studies (Oser et al..
1965a. b) had large sample sizes, longer treatment durations, and evaluated a comprehensive set
of endpoints. These studies are therefore considered more reliable. The 1- and 2-year rat
chronic-duration studies had NOAELs of 7,108 mg/kg-day (Oser et al.. 1965b) and 533.1
mg/kg-day (Oser et al.. 1965a). respectively, based on no observed effects at the highest dose
tested, suggesting that the NOAEL of 7,108 mg/kg-day is protective for systemic toxicity. A
NOAEL of 604.7 mg/kg-day was established based on no observed effects in the rat reproductive
study by Oser et al. (1965e). This study included the examination of parental animals and three
generations of offspring. While the NOAEL of 7,108 mg/kg-day from the 1 -year rat study (Oser
et al., 1965b) is protective for systemic toxicity, the lower reproductive NOAEL of
604.7 mg/kg-day from the rat reproductive toxicity study (Oser et al., 1965e) is selected for
derivation of both subchronic and chronic p-RfDs because (1) there are no data indicating
whether reproductive toxicity would be observed at doses between the reproductive NOAEL of
604.7 mg/kg-day and the systemic NOAEL of 7,108 mg/kg-day, and (2) the reproductive
NOAEL is more sensitive than the systemic NOAEL, thus, it is protective for all potential
reproductive and systemic toxicity.
An example calculation of the adjusted dosimetry for ADA from Oser et al. (1965) is as
follows:
DoseADj = Dose x Food Consumption per Day x (l -h Body Weight Animal) x
(Days Dosed ^ Total Days)
Where:
Food Consumption = 0.0262 kg/day
Body Weight Animal = 0.3194 kg
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DoseADJ = 7,500 ppm (HADA) x 0.0262 kg/day x (1 - 0.3194 kg) x
(730 -h 730)
= 196.5 x 3.1309 kg"1 x 1
= 615.2 mg/kg-day (HADA)
Note: Food consumption and body weight are default values from average of five strains
of female rats (Fischer, Long-Evans, Osborne-Mendel, Sprague-Dawley, and
Wistar; data from Tables 3-5 and Tables 1-6 (U.S. EPA. 1988).
Conversion from HAD A to ADA
Where:
Molecular wt. ADA = 116.08 g/mol
Molecular wt. HADA = 118.09 g/mol
DoseADJ = 615.2x116.08-118.09
= 604.7 mg/kg-day (ADA)
In Recommended Use of Body Weight3/4 as the Default Method in Derivation of the Oral
Reference Dose (U.S. EPA. 2011b). the Agency endorses a hierarchy of approaches to derive
human equivalent oral exposures from data from laboratory animal species, with the preferred
approach being physiologically based toxicokinetic modeling. Other approaches may include
using some chemical-specific information, without a complete physiologically based
toxicokinetic model. In lieu of chemical-specific models or data to inform the derivation of
human equivalent oral exposures, EPA endorses body-weight scaling to the 3/4 power
(i.e., BW3 4) as a default to extrapolate toxicologically equivalent doses of orally administered
agents from all laboratory animals to humans for the purpose of deriving an RfD under certain
exposure conditions. More specifically, the use of BW3 4 scaling for deriving an RfD is
recommended when the observed effects are associated with the parent compound or a stable
metabolite, but not for portal-of-entry effects or developmental end points.
A validated human PBPK model for ADA is not available for use in extrapolating doses
from animals to humans. The selected NOAEL from the rat reproductive study was associated
with the parent compound or a stable metabolite. Furthermore, the NOAEL is not based on
portal-of-entry or developmental effects. Therefore, scaling by BW3 4 is relevant for deriving
human equivalent doses (HEDs) for these effects.
Following U.S. EPA (2011b) guidance, the POD for the rat reproductive study is
converted to an HED through an application of a dosimetric adjustment factor (DAF1) derived as
follows:
DAF = (BWa1/4 - BWh1/4)
:As described in detail in Recommended Use of Body Weight3/4 as the Default Method in Derivation of the Oral
Reference Dose (U.S. EPA. 2011b'). rate-related processes scale across species in a manner related to both the direct
(BW11) and allometric scaling (BW3'4) aspects such that BW34 - BW11 = BW"1'4, converted to a
DAF = BWa1/4 - BWh1/4.
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Where:
DAF = dosimetric adjustment factor
BWa = animal body weight
BWh = human body weight
Using a BWa of 0.25 kg for rats and a BWh of 70 kg for humans (U.S. EPA. 1988). the
resulting DAF is 0.244. Applying this DAF to the NOAEL identified in the rat reproductive
study yields a PODhed as follows:
PODhed =	NOAELadj (mg/kg-day) x DAF
=	NOAELadj (mg/kg-day) x 0.244
=	604.7 (mg/kg-day) x 0.244
=	147.5 mg/kg-day
Subchronic p-RfD = PODhed UFc
= 147.5 mg/kg-day -M00
= 1 x 10° mg/kg-day
Table 6 summarizes the uncertainty factors (UFs) for the subchronic p-RfD for ADA.
Table 6. UFs for the Subchronic p-RfD for ADA
UF
Value
Justification
UFa
3
A UFa of 3 (10°5) has been applied to account for uncertainty in characterizing the
toxicodynamic differences between rats and humans following oral ADA exposure. The
toxicokinetic uncertainty has been accounted for by calculation of a HED through application
of a DAF as outlined in the EPA's Recommended Use of Body Weight3/4 as the Default
Method in Derivation of the Oral Reference Dose U.S. EPA (20 lib).
ufd
3
A UFd of 3 has been applied because there is one acceptable multi-generation reproductive
toxicity studv in rats COser et al.. 1965e) in addition to subchronic- and chronic-duration
studies. However, there is no acceptable developmental toxicity study via the oral route.
UFh
10
A UFh of 10 has been applied for inter-individual variability to account for human-to-human
variability in susceptibility in the absence of quantitative information to assess the
toxicokinetics and toxicodynamics of ADA in humans.
ufl
1
A UFl of 1 has been applied for LOAEL-to-NOAEL extrapolation because the POD is a
NOAEL
UFS
1
A UFS of 1 has been applied because lack of reproductive toxicity was used as the
POD/critical effect and is more sensitive than effects observed in the available subchronic -
and chronic-duration studies.
UFC
100
UFC = UFa x UFd x UFh * UFL x UFS
The confidence in the subchronic p-RfD for ADA is medium as explained in Table 7
below.
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Table 7. Confidence Descriptors for Subchronic p-RfD for ADA
Confidence Categories
Designation"
Discussion
Confidence in study
M
The study does not meet OECD Guideline 416 and
OPPTS 870.3800 guidelines. For example, average weight of
pups was only reported at 21 days, and the study authors did not
monitor female estrous cycles or male sperm parameters (sperm
motility and sperm morphology; total number of
homogenization-resistant testicular spermatids and cauda
epididymal sperm); however, it is a three-generation study with a
suitable number of test animals and a variety of systemic
parameters evaluated.
Confidence in database
M
The database lacks a developmental toxicity study.
Confidence in subchronic
p-RfDb
M
The overall confidence in the subchronic p-RfD is medium.
"L = low; M = medium; H = high.
bThe overall confidence cannot be greater than the lowest entry in the table.
Derivation of Chronic Provisional RfD (Chronic p-RfD)
The principal study selected for derivation of the chronic p-RfD is the reproductive
study by Oser et al. (1965e). The database includes four chronic-duration studies in rats and
dogs (Oser et al.. 1965a. b. c. d). Two of the studies in rats are comprehensive studies and have
NOAELs based on no observed effects at doses up to 533.1 mg/kg-day (Oser et al.. 1965a) and
7,108 mg/kg-day (Oser et al.. 1965b). The 1- and 2-year dog chronic-duration studies by Oser et
al. (1965c. d) are limited due to small sample size (2/sex/group) and lack of a control group in
the 1-year study. While the NOAEL of 7,108 is protective for systemic effects after chronic
exposure, the NOAEL of 604.7 mg/kg-day based on no observed reproductive effects from the
reproductive toxicity study (Oser et al.. 1965e) is selected because it is more sensitive and is
protective for any potential chronic and reproductive toxicity. Therefore, the same POD of
147.5 mg/kg-day (a NOAEL) used for deriving the subchronic p-RfD is used to derive the
chronic p-RfD.
Chronic p-RfD = PODHed UFC
= 147.5 mg/kg-day -MOO
= 1 x 10° mg/kg-day
Table 8 summarizes the UFs for the chronic p-RfD for ADA.
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Table 8. UFs for the Chronic p-RfD for ADA
UF
Value
Justification
ufa
3
A UFa of 3 (10°5) has been applied to account for uncertainty in characterizing the
toxicodynamic differences between rats and humans following oral ADA exposure.
The toxicokinetic uncertainty has been accounted for by calculation of a HED through
application of a DAF as outlined in the EPA's Recommended Use of Body Weight3/4 as
the Default Method in Derivation of the Oral Reference Dose U.S. EPA (201 lb).
ufd
3
A UFd of 3 has been applied because there is one acceptable multi-generation
reproductive toxicity study in rats COser et al.. 1965e) in addition to two
comprehensive chronic-duration studies. However, there is no acceptable
developmental toxicity study via the oral route.
UFh
10
A UFh of 10 has been applied for inter-individual variability to account for human-to-
human variability in susceptibility in the absence of quantitative information to assess
the toxicokinetics and toxicodynamics of ADA in humans.
ufl
1
A UFl of 1 has been applied for LOAEL-to-NOAEL extrapolation because the POD is
a NOAEL.
UFS
1
A UFS of 1 has been applied because lack of reproductive toxicity was used as the
POD/critical effect and is more sensitive than effects observed in the available
subchronic- and chronic-duration studies.
UFC
100
UFC = UFa x UFd x UFh x UFl x UFs
The confidence in the chronic p-RfD for ADA is medium as explained in Table 9 below.
Table 9. Confidence Descriptors for Chronic p-RfD for ADA
Confidence Categories
Designation"
Discussion
Confidence in study
M
The study does not meet OECD Guideline 416 and
OPPTS 870.3800 guidelines. For example, average weight of
pups was only reported at 21 days, and the study authors did not
monitor female estrous cycles or male sperm parameters (sperm
motility and sperm morphology; total number of
homogenization-resistant testicular spermatids and cauda
epididymal sperm); however, it is a three-generation study with a
suitable number of test animals and a variety of systemic
parameters evaluated.
Confidence in database
M
The database lacks a developmental toxicity study.
Confidence in chronic
p-RfDb
M
The overall confidence in the chronic p-RfD is medium.
aL = low; M = medium; H = high.
bThe overall confidence cannot be greater than the lowest entry in the table.
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DERIVATION OF INHALATION REFERENCE CONCENTRATIONS
Derivation of Subchronic Provisional RfC (Subchronic p-RfC)
Whitehead et al. (1987) is chosen as the principal study for the derivation of the
subchronic p-RfC. The effects of inhalation exposure of humans to ADA were evaluated in
seven long-term-duration studies and case reports (Kim et al.. 2004; Normand et al.. 1989;
Whitehead et al.. 1987; Ahrenholz et al, 1985; \1alo et al, 1985; Slovak, 1981; Ferris et al,
1977). Kim et al. (2004). Normand et al. (1989). and Malo et al. (1985) are case studies
(1-4 cases). The case study reports are of limited use because the subjects were self-reported,
and the reports had no control (unexposed subjects) and dosimetry data. While Ferris et al.
(1977) and Slovak (1981) provided dosimetry data, the subjects were exposed to much a higher
3	3
concentration of ADA (0.25-0.75 mg/m and 0.7-1.8 mg/m , respectively) than the Whitehead
et al. (1987) study (0.00689 mg/m3). The Ahrenholz et al. (1985) study design is problematic.
For instance, in this study, the exposed subjects were actually from two different groups: one
group with direct exposure (handling ADA directly), and the other group with indirect exposure
(working in the same room but not handling ADA). As a result, the ADA exposure
concentrations collected from indirectly exposed workers actually are much lower than the direct
3	3
exposure (0.0036 mg/m vs. 1.3 mg/m ). The study authors combined indirectly and directly
exposed workers in a pooled analysis of symptoms compared with unexposed workers, which
resulted in uncertainty in identifying a true exposure level in the exposed worker group.
In the Whitehead et al. (1987) study, a LOAEL was identified as 0.00689 mg/m3
(adjusted) based on respiratory effects including irritation, cough, wheezing (associated with
shortness of breath), and chronic bronchitis, supported by decrements in FEVi and FVC in
ADA-exposed injection molding workers. In the group of 17 workers given pre- and postshift
pulmonary function tests, statistically significant, but modest decrements in mean FEVi and FVC
values were reported although no consistent dose-response trend was present among exposure
levels or years worked in injection molding.
Although the LOAEL of 0.00689 mg/m3 from the Whitehead et al. (1987) study is not the
lowest and most sensitive value in the human database, of all the available human studies, it is
the only study considered as a candidate principal study because the study design was the most
rigorous with (1) a relatively large sample size (total of 227 subjects), (2) comparison of exposed
groups to unexposed controls, (3) complete exposure and health effect data, (4) reporting and
measurement of other chemical exposures in the workplace, and (5) consideration and
adjustment for possible confounders.
Limited subchronic-duration animal inhalation data (Medinsky et al.. 1990; Getiach et
al.. 1989) were available for ADA, but these studies were not selected as the principal study for
derivation of the subchronic p-RfC because their identified NOAEL values (52.8 [guinea pig],
60.6 [rat], and 196 mg/m [mouse]) were well above the LOAEL identified in the Whitehead et
al. (1987) human study (0.00689 mg/m3). Furthermore, adequate human data are considered the
most relevant for determining the health effects of a substance to humans and should be used to
establish reference values when available. Thus, the LOAEL of 0.00689 mg/m3 from the
Whitehead et al. (1987) study is identified as the POD for derivation of the subchronic p-RfC.
An example calculation of the adjusted concentration for ADA is as follows:
ConcADJ = Cone x (VEho ^ VEh) x (work days per week ^ 7 days)
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Where (US. EPA. 1994b):
VEho (human occupational default minute volume) = 10 m /8 hour
"3
VEh (human ambient minute volume) = 20 m /24 hour
ConcADJ = 0.0193 mg/m3 x (10 - 20) x (5 - 7)
= 0.00689 mg/m3. Based on the LOAEL of 0.00689 mg/m3 from the
Whitehead et al. (1987) study as the POD, the subchronic p-RfC is
derived as follows:
Subchronic p-RfC = POD - UFc
= 0.00689 mg/m3-1,000
= 7 x 10"6 mg/m3
Table 10 summarizes the UFs for the subchronic p-RfC for ADA.
Table 10. UFs for the Subchronic p-RfC for ADA
UF
Value
Justification
UFa
1
A UFa of 1 has been applied because a human study is selected as the principal study.
ufd
10
A UFd of 10 has been applied because there are no acceptable two-generation
reproductive toxicity or developmental toxicity studies via the inhalation route.
UFh
10
A UFh of 10 has been applied for inter-individual variability to account for human-to-
human variability in susceptibility in the absence of quantitative information to assess
the toxicokinetics and toxicodynamics of ADA in humans.
ufl
10
A UFl of 10 has been applied for LOAEL-to-NOAEL extrapolation because the POD is
a LOAEL.
UFS
1
A UFS of 1 has been applied because a subchronic-duration study was selected as the
principal study.
UFC
1,000
UFC = UFa x UFd x UFh x UFl x UFs
The confidence in the subchronic p-RfC for ADA is medium as explained in Table 11
below.
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Table 11. Confidence Descriptors for the Subchronic p-RfC for ADA
Confidence Categories
Designation"
Discussion
Confidence in study
M
Confidence in the tmncitJal studv is medium. Whitehead et al. CI987) is a
peer-reviewed, occupational study with individual exposure data. The
critical respiratory effects were also reported in several other
peer-reviewed studies (Kim et al. 2004; Normand et al.. 1989; Ahrenholz
et al.. 1985; Slovak. 1981). However, it is unclear if respiratory effects
occurred in workers exposed below the mean personal sampling value of
0.00689 mg/m3 (adjusted), which was identified as the LOAEL and used
as the POD.
Confidence in database
M
The database contains three long-term human occupational studies that
suffer from some methodological weaknesses but provide convincing data
in support of the critical respiratory effects; four other human case studies
provide supporting evidence. However, no developmental and
reproductive toxicity studies are available.
Confidence in
subchronic p-RfCb
M
The overall confidence in the subchronic p-RfC is medium.
aL = low; M = medium; H = high.
bThe overall confidence cannot be greater than the lowest entry in the table.
Derivation of Chronic Provisional RfC (Chronic p-RfC)
Whitehead et al. (1987) is chosen as the principal study for the derivation of the
chronic p-RfC. The human database is discussed in the Derivation of Subchronic Provisional
RfC section; please refer to this section for an explanation of principal study selection. The
LOAEL (and POD) for the critical effects was identified as 0.00689 mg/m after adjusting for
continuous exposure. Although the principal study. Whitehead et al. (1987). does not meet the
guideline definition of chronic exposure duration for humans put forth in U.S. EPA guidance
(U.S. EPA, 2002), there is no need to extrapolate from subchronic to chronic exposure duration
with respect to effects induced by a respiratory sensitizer. Once sensitized, longer
exposure-duration does not make any difference compared to a short-duration exposure. This
also helps explain why the effect is not dose dependent but still biologically significant. As a
result, the chronic p-RfC has a UFS of 1 (see Table 12). When combined with the other
uncertainty factors, the UFc is 1,000.
Based on the LOAEL of 0.00689 mg/m3 from the Whitehead et al. (1987) study as the
POD, the subchronic p-RfC is derived as follows:
Chronic p-RfC = POD-UFc
= 0.00689-1,000
= 7 x 10"6 mg/m3
Table 12 summarizes the UFs for the chronic p-RfC for ADA. The confidence in the
subchronic p-RfC for ADA is medium as explained in Table 13 below.
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Table 12. UFs for Screening Chronic p-RfC for ADA
UF
Value
Justification
ufa
1
A UFa of 1 has been applied because a human study is selected as the principal study.
ufd
10
A UFd of 10 has been applied because there are no acceptable two-generation
reproductive toxicity or developmental toxicity studies via the inhalation route.
UFh
10
A UFh of 10 has been applied for inter-individual variability to account for human-to-
human variability in susceptibility in the absence of quantitative information to assess
the toxicokinetics and toxicodynamics of ADA in humans.
ufl
10
A UFl of 10 has been applied for LOAEL-to-NOAEL extrapolation because the POD
is a LOAEL.
UFS
1
A UFS of 1 has been applied for using data from a subchronic-duration human study
because with respect to respiratory sensitization, there is no need to extrapolate from
subchronic- to chronic-duration exposure.
UFC
1,000
UFC = UFa x UFd x UFh x UFl x UFs
Table 13. Confidence Descriptors for the Chronic p-RfC for ADA
Confidence Categories
Designation"
Discussion
Confidence in study
M
Confidence in the kev studv is medium. Whitehead et al. n 987^ is a
peer-reviewed, occupational study with individual exposure data.
The critical effects of respiratory effects were also reported in
several other Deer-reviewed studies (Kim et al.. 2004; Normand et
al.. 1989; Ahrenholz et al.. 1985; Slovak, 1981). However, it is
unclear if respiratory effects occurred in workers exposed below the
mean personal sampling value of 0.00689 mg/m3 (adjusted), which
was identified as the LOAEL and used as the POD.
Confidence in database
M
The database contains three long-term human occupational studies
that suffer from some methodological weaknesses but provide
convincing data in support of the critical effects; four other human
case studies provide supporting evidence. However, no
developmental and reproductive studies are available.
Confidence in chronic
p-RfCb
M
The overall confidence in the subchronic p-RfC is medium.
aL = low; M = medium; H = high.
bThe overall confidence cannot be greater than the lowest entry in the table.
CANCER WEIGHT-OF-EVIDENCE (WOE) DESCRIPTOR
A cancer WOE descriptor for ADA cannot be identified (see Table 14).
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Table 14. Cancer WOE Descriptor for ADA
Possible WOE
Descriptor
Designation
Route of Entry (Oral,
Inhalation, or Both)
Comments
"Carcinogenic to
Humans "
NS
NA
No human carcinogenicity data are available.
"Likely to Be
Carcinogenic to
Humans "
NS
NA
No animal carcinogenicity data are available.
"Suggestive Evidence oj
Carcinogenic
Potential"
NS
NA
No animal carcinogenicity data are available.
"Inadequate
Information to Assess
Carcinogenic
Potential"
Selected
Both
This descriptor is selected due to the lack
of any information on the carcinogenicity
of ADA.
"Not Likely to Be
Carcinogenic to
Humans "
NS
NA
There are no data to indicate that ADA is not
carcinogenic.
NA = not applicable; NS = not selected.
DERIVATION OF PROVISIONAL CANCER POTENCY VALUES
The lack of data on the carcinogenicity of ADA precludes the derivation of quantitative
estimates for either oral (p-OSF) or inhalation (p-IUR) exposure.
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APPENDIX A. PROVISIONAL SCREENING VALUES
No screening values are presented.
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APPENDIX B. DATA TABLES
Table B.l. Measured ADA Exposure by Occupation in the Leon Plastics Plant in Grand
Rapids, Michigan"
Sample Description
ADA Concentration (jig/m3)
(personal sampling)
Job Title
Workshift Hours
Duration (min)
Injection mold operator
11-7
451
Trace
Injection mold operator
11-7
447
14
Injection mold operator
11-7
415
10
Injection mold operator
11-7
428
13
Injection mold operator
11-7
449
10
Injection mold operator
11-7
424
11
Injection mold operator
11-7
420
6
Injection mold operator
11-7
448
8
Injection mold operator
11-7
445
6
Material handler
11-7
468
12
Injection mold operator
7-3
444
26
Injection mold operator
7-3
442
22
Injection mold operator
7-3
442
24
Injection mold operator
7-3
412
34
Injection mold operator
7-3
392
27
Injection mold operator
7-3
422
36
Injection mold operator
7-3
22
48
Injection mold operator
7-3
24
57
Injection mold operator
7-3
34
368b
Material handler
7-3
27
752°
Injection mold operator
7-3
36
33
Injection mold operator
3-11
48
12
Injection mold operator
3-11
427
27
Injection mold operator
3-11
455
30
Injection mold operator
3-11
85d
47
Injection mold operator
3-11
455
45
Injection mold operator
3-11
452
48
Injection mold operator
3-11
434
43
Injection mold operator
3-11
437
9
Injection mold operator
3-11
452
8
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Table B.l. Measured ADA Exposure by Occupation in the Leon Plastics Plant in Grand
Rapids, Michigan"
Sample Description
ADA Concentration (jig/m3)
(personal sampling)
Job Title
Workshift Hours
Duration (min)
Injection mold operator
3-11
447
24
Material handler
3-11
436
57
aNIOSH (19851.
bWork station was located across from the resin mixing area.
°Worker mixed ADA with resins.
dSample was terminated early due to the employee's refusal to continue wearing sampling pump.
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Table B.2. Symptoms Reported After Occupational Exposure to ADA in
Current Departments Versus Former Departments3
Symptom
% of Current Other
Department
Workers Reporting
Symptom
(n = 93)
% of Current
Injection Mold
Workers Reporting
Symptom
(n = 110)
Odds Ratio (/>-valuc)
Reported for Current
Department
Odds Ratio (/>-valuc)
Reported for Former
Departments'"
Irritation0
34.4
48.2
1.77 (0.04)
5.25 (0.0001)
Cough
31.2
47.3
1.98 (0.02)
2.83 (0.03)
Wheezingd
14.0
30.9
2.75 (0.004)
2.96 (0.06)
Shortness of
breath6
20.4
20.0
0.97 (0.99)
2.87 (0.03)
Chest tightnessf
15.1
16.4
1.11 (0.80)
1.45 (0.55)
Headache
35.5
50.0
1.82 (0.04)
2.88 (0.02)
Skin rash
18.3
23.6
1.38 (0.35)
1.34 (0.59)
"Whitehead et al. (19871.
bExcludes current department.
"Question asked "Did you have irritation or burning of the eyes, nose, or throat at least once per month while
working in (department name)?"
dQuestions asked about "wheezing or whistling sound in your chest apart from colds."
"Questions asked about "shortness of breath, difficulty catching your breath, or a smothering feeling."
fQuestions asked about "chest tightness or a sensation of a band around the chest."
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Table B.3. Symptoms Reported by Presence or Absence of Potentially Significant Exposure
to ADA in Injection Moldinga'b
Symptom
% Reporting, Unexposed
(n = 34)
% Reporting, Exposed
(n = 136)
Odds Ratio (/j-valuc)
ATS symptoms0
Wheezing associated with:
Shortness of breath
2.9
19.1
7.80 (0.01)
Wheeze most days
11.8
19.1
1.77 (0.27)
Chronic bronchitis'1
11.8
31.6
3.47 (0.02)
Grade 2+ dypsnea"
5.9
12.5
2.29 (0.27)
Symptoms reported while working in injection molding
Irritation
38.2
47.8
1.48 (0.21)
Cough
32.4
41.9
1.51 (0.31)
Wheezing
2.9
33.1
16.32 (0.0001)
Shortness of breath
17.6
20.6
1.21 (0.70)
Chest tightness
2.9
16.9
6.72 (0.02)
Headache
35.3
43.4
1.40 (0.25)
Skin rash
17.6
19.9
1.16(0.49)
"Whitehead et al. (19871.
b"Potentially significant exposure to ADA" defined as persons who worked in injection molding for 1 day or longer
during the period from January I, 1980, through 4 mo before the interview date.
°ATS = American Thoracic Society; standard set of questions.
dCough or phlegm on most days for 3 mo of yr for 2 or more yr.
"Answered "yes" to "have to walk slower than other people of your age on level ground because of shortness of
breath."
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Table B.4. Measured ADA Exposure by Occupation in an Armstrong World Industries
Floor Plant in Lancaster, Pennsylvaniaa'b
Sample Description
ADA Concentration (mg/m3)
Job Title
Duration (min)
Indirect Exposure0
Direct Exposure0
Exposed workers (individual measures)
Leader
346
0.01
ND
Helper
344
0.02
ND
Grinder
32
ND
3.8
308
0.03
ND
Leader
396
BD
ND
Helper
419
Trace
ND
Grinder
56
ND
12
354
BD
ND
Grinder
406
Trace
ND
Grinder
305
BD
ND
Helper
311
BD
ND
Leader
304
0.02
ND
Grinder
53
ND
0.15
257
0.02
ND
Leader
354
0.01
ND
Helper
27
ND
4.8
391
0.02
ND
Leader
397
0.01
ND
Helper
401
0.04
ND
31
ND
4.8
373
0.10
ND
Leader
388
Trace
ND
Helper
385
Trace
ND
11
ND
0.59
353
Trace
ND
Leader
418
BD
ND
Helper
415
BD
ND
7
ND
0.63
409
Trace
ND
Leader
426
Trace
ND
Helper
414
BD
ND
21
ND
1.6
330
0.03
ND
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Table B.4. Measured ADA Exposure by Occupation in an Armstrong World Industries
Floor Plant in Lancaster, Pennsylvaniaa'b
Sample Description
ADA Concentration (mg/m3)
Job Title
Duration (min)
Indirect Exposure0
Direct Exposure0
Unexposed workers (coating and fusion department; individual measures)
Coater operator
423
BD
ND
Roll-up operator
430
Trace
ND
Unroll operator
415
Trace
ND
Roll-up operator
421
BD
ND
Line Operator
380
Trace
ND
Laborer
368
BD
ND
Roll-up operator
363
BD
ND
Leader
369
BD
ND
Coater operator
414
BD
ND
Coater operator
403
BD
ND
Unroll operator
401
BD
ND
Roll-up operator
397
BD
ND
"Alirenliolz et al. (1985').
bTwo workers who had combined indirect and direct exposure are not included in this table.
Direct exposure: short-term exposure while handling the compound; indirect exposure: full-shift worker, working
in the vicinity where ADA was used.
BD = below detection level; ND = no data.
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Table B.5. Symptom Observations and Risk Calculations
After Occupational Exposure to ADAa
Observations
Exposure Group
Ever Exposedb
Never Exposed
Number of participants examined
30
16
Number (%) of participants with lower respiratory tract symptoms
18 (60)
1(6)
Risk ratio for lower respiratory tract symptoms
10*
1
Number (%) of participants with upper respiratory tract/eye symptoms
26 (87)
5(31)
Risk ratio for upper respiratory tract/eye symptoms
2.8**
1
aAlirenliolz et al. (1985').
bThe ever-exposed group included workers both directly and indirectly exposed to ADA.
*p = 0.0004.
**p = 0.0001.
Table B.6. 125I Uptake, Relative Thyroid Weight, Body Weight, and Protein-Bound Iodine
of Male Sprague-Dawley Rats After Dietary Exposure to ADA for 4 Weeks"
Parameter0
Exposure Group,
% Diet (Adjusted Daily Dose, ADD, mg/kg-d)b
0(0)
10 (8,600)
Sample size
12
11
125IUptaked
42.42 ±3.86
31.59 ± 8.37 (74%)***
Relative thyroid weight (g per 100 g body weight)
14.8 ±2.3
13.6 ± 1.9(92%)
Mean total body weight on last day of experiment (g)
214 ± 17
200 ± 17 (93%)
"Gafford et al. (197D.
bCalculated by reviewers using the average body weight provided in the study.
°Values expressed as mean ± SD (% of control); % was calculated.
d24-hr thyroidal 125I uptake (%) ± SD.
***Statistically significant relative to controls,/) < 0.001.
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Table B.7. Mean Reproduction and Lactation Data for
Three-Generation Reproductive Toxicity Study of ADA3
Parameterb
Dose Group (mg/kg-d, adjusted)
0 ppm
(0) HADA
750 ppm
(60.5) HADA
2,370 ppm
(191.1)
HADA
7,500 ppm
(604.7)
HADA
0 ppm
(0) ADA
100 ppm
(8) ADA
F0 generation
Average # pups
At birth
At weaning

8.3
7.8 (94)
9.2(111)
9.7(117)
8.8
8.7 (99)
6.5
6.8(105)
7.8 (120)
7.6(117)
8.0
7.5 (94)
Average pup
weight at 21 d
49.5
47.3 (96)
50.2(101)
50.8 (103)
44.5
44.3 (100)
Fertility index0
57
64 (112)
72 (126)
40 (70)
88
80 (91)
Gestation indexd
100
100 (100)
100 (100)
100 (100)
96
94 (98)
Viability index6
68
70 (103)
67 (99)
84 (124)
84
86 (102)
Lactation indexf
89
89 (100)
85 (96)
88 (99)
84
85 (101)
F1 generation
Average # pups
At birth
At weaning

9.5
9.9(105)
9.8(103)
9.7 (102)
10.0
10.1 (101)
7.2
7.9(110)
8.6(119)
8.3 (115)
8.2
8.3 (101)
Average pup
weight at 21 d
45.0
49.0 (109)
44.0 (98)
46.7 (104)
46.3
47.7 (103)
Fertility index0
95
90 (95)
70 (74)
85 (89)
90
65 (72)
Gestation indexd
95
94 (99)
100 (105)
100 (105)
100
100 (100)
Viability index0
62
80 (129)
83 (134)
82 (132)
80
73 (91)
Lactation indexf
88
95 (108)
96 (109)
92 (105)
91
96 (105)
F2 generation
Average # pups
At birth
At weaning

9.3
8.4 (90)
7.8 (84)
9.1 (98)
9.4
9.5 (101)
6.6
6.0(91)
6.7 (102)
7.9 (120)
8.0
7.9 (99)
Average pup
weight at 21 d
47.1
47.4(101)
46.4 (99)
45.5 (97)
44.2
40.0 (90)
Fertility index0
90
80 (89)
95 (106)
90 (100)
95
90 (95)
Gestation indexd
100
94 (94)
100 (100)
100 (100)
100
95 (95)
Viability index0
60
60 (100)
72 (120)
82 (137)
84
85 (101)
Lactation indexf
93
99 (106)
99 (106)
99 (106)
96
98 (102)
"Oseretal. (1965).
' Parameters presented as mean (% of controls); based on 50 matings per group in F0 and 20 matings per group in F1
and F2.
°Pregnancies ^ matings x 100 (%).
dLitters born pregnancies x 100 (%).
ePups surviving at 4 d ^ pups born x 100 (%).
fPups weaned pups at 4 d x 100 (%).
HADA = biurea, metabolite of ADA parent compound.
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APPENDIX C. BMD OUTPUTS
BMDS was not ran on any of the studies in the database because data were unsuitable.
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