DRAFT DELIBERATIVE: FOR INTERAGENCY REVIEW ONLY.

DO NOT DISTRIBUTE OUTSIDE YOUR AGENCY.

EPA/635/R-14/303

Interagency Review Draft

www.epa.gov/iris 

Toxicological Review of Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX)

(CASRN 121-82-4) 

In Support of Summary Information on the

Integrated Risk Information System (IRIS)

Supplemental Information

September 2014

NOTICE

This document is an Interagency Review Draft. This information is distributed solely for the 

purpose of pre-dissemination peer review under applicable information quality guidelines. It has 

not been formally disseminated by EPA. It does not represent and should not be construed to 

represent any Agency determination or policy. It is being circulated for review of its technical 

accuracy and science policy implications.

National Center for Environmental Assessment

Office of Research and Development

U.S. Environmental Protection Agency

Washington, DC 
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This document is a draft for review purposes only and does not constitute Agency policy.

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DISCLAIMER

This document is a preliminary draft for review purposes only. This information is 

distributed solely for the purpose of pre-dissemination peer review under applicable information 

quality guidelines. It has not been formally disseminated by EPA. It does not represent and should 

not be construed to represent any Agency determination or policy. Mention of trade names or 

commercial products does not constitute endorsement of recommendation for use.
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This document is a draft for review purposes only and does not constitute Agency policy.

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CONTENTS

APPENDIX A. ASSESSMENTS BY OTHER NATIONAL AND INTERNATIONAL HEALTH AGENCIES ............ A-1

APPENDIX B. ADDITIONAL DETAILS OF LITERATURE SEARCH STRATEGY | STUDY SELECTION 

AND EVALUATION............................................................................................................ B-1

APPENDIX C. INFORMATION IN SUPPORT OF HAZARD IDENTIFICATION AND DOSE-RESPONSE 

ANALYSIS.......................................................................................................................... C-1

C.1. CHEMICAL PROPERTIES.......................................................................................... C-1

C.2. TOXICOKINETICS..................................................................................................... C-2

C.2.1. Absorption................................................................................................. C-2

C.2.2. Distribution ............................................................................................... C-6

C.2.3. Metabolism............................................................................................... C-8

C.2.4. Excretion ................................................................................................. C-10

C.2.5. Physiologically-Based Pharmacokinetic (PBPK) Models ......................... C-12

C.3. HUMAN STUDIES.................................................................................................. C-30

C.4. OTHER PERTINENT TOXICITY INFORMATION....................................................... C-38

APPENDIX D. DOSE-RESPONSE MODELING FOR THE DERIVATION OF REFERENCE VALUES FOR 

EFFECTS OTHER THAN CANCER AND THE DERIVATION OF CANCER RISK 

ESTIMATES ...................................................................................................................... D-1

D.1. BENCHMARK DOSE MODELING SUMMARY FOR NONCANCER ENDPOINTS......... D-1

D.1.1. Evaluation of Model Fit............................................................................ D-2

D.1.2. Model Selection ....................................................................................... D-2

D.1.3. Modeling Results...................................................................................... D-3

D.2. BENCHMARK DOSE MODELING SUMMARY FOR CANCER ENDPOINTS .............. D-39

D.2.1. Evaluation of Model Fit and Model Selection........................................ D-39

D.2.2. Modeling Results.................................................................................... D-40

REFERENCES FOR APPENDICES .................................................................................................................. R-1
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TABLES 

Table A-1. Assessments by Other National and International Health Agencies....................................... A-1

Table B-1. Summary of detailed search strategies for RDX (Pubmed, Toxline, Toxcenter, TSCATS)........ B-3

Table B-2. Summary of detailed search strategies for RDX (DTIC) ......................................................... B-10

Table B-3. Processes used to augment the search of core databases for RDX....................................... B-11

Table B-4. Summary disposition of DTIC database citations .................................................................. B-13

Table C-1. Chemical identity and physicochemical properties of RDX ..................................................... C-1

Table C-2. Distribution of RDX or radiolabel from administered RDXa ..................................................... C-8

Table C-3. Principal urinary metabolites of RDX in miniature swine 24 hours after dosing with 

RDX................................................................................................................................. C-10

Table C-4. Elimination t1/2 values for RDX or radiolabeled RDX.............................................................. C-11

Table C-5. Parameter values used in the Sweeney et al. (2012a) and Sweeney et al. (2012b) 

PBPK models for RDX in rats, humans, and mice........................................................... C-14

Table C-6. Parameters values used in the EPA application of the rat, human, and mouse models....... C-17

Table C-7. Doses, dosing formulations, and absorption rate constants in animal and human 

studies............................................................................................................................ C-19

Table C-8. Sensitivity coefficients for rat and human RDX PBPK models ............................................... C-27

Table C-9. Summary of case reports of exposure to RDX ....................................................................... C-31

Table C-10. Epidemiologic studies of RDX: summary of methodologic features.................................... C-35

Table C-11. Summary of in vitro studies of the genotoxicity of RDX...................................................... C-41

Table C-12. Summary of in vivo studies of the genotoxicity of RDX....................................................... C-44

Table C-13. Summary of in vitro and in vivo studies of the genotoxicity of RDX metabolites ............... C-45

Table D-1. Noncancer endpoints selected for dose-response modeling for RDX.................................... D-1

Table D-2. Model predictions for convulsions in female F344 rats exposed to RDX by gavage for

90 days (Crouse et al., 2006); BMR = 10% extra risk ...................................................... D-3

Table D-3. Model predictions for convulsions in female F344 rats exposed to RDX by gavage for 

90 days (Crouse et al., 2006); BMR= 5% extra risk ......................................................... D-6

Table D-4. Model predictions for convulsions in female F344 rats exposed to RDX by gavage for 

90 days (Crouse et al., 2006); BMR= 1% extra risk ......................................................... D-9

Table D-5. Model predictions for convulsions in male F344 rats exposed to RDX by gavage for 90 

days (Crouse et al., 2006); BMR = 10% extra risk ......................................................... D-11

Table D-6. Model predictions for convulsions in male F344 rats exposed to RDX by gavage for 90 

days (Crouse et al., 2006); BMR = 5% extra risk ........................................................... D-14

Table D-7. Model predictions for convulsions in male F344 rats exposed to RDX by gavage for 90 

days (Crouse et al., 2006); BMR = 1% extra risk ........................................................... D-17

Table D-8. Model predictions for convulsions in male and female F344 rats exposed to RDX by 

gavage for 90 days (Crouse et al., 2006); BMR = 10% extra risk .................................. D-19

Table D-9. Model predictions for convulsions in male and female F344 rats exposed to RDX by 

gavage for 90 days (Crouse et al., 2006); BMR = 5% extra risk .................................... D-22

Table D-10. Model predictions for convulsions in male and female F344 rats exposed to RDX by 

gavage for 90 days (Crouse et al., 2006); BMR = 1% extra risk .................................... D-25

Table D-11. Model predictions for convulsions in female F344 rats exposed to RDX by gavage on 

gestation days 6−19 (Cholakis, 1980); BMR = 10% extra risk ....................................... D-27

Table D-12. Model predictions for convulsions in female F344 rats exposed to RDX by gavage on 

gestation days 6−19 (Cholakis, 1980); BMR = 5% extra risk ......................................... D-29
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Table D-13. Model predictions for convulsions in female F344 rats exposed to RDX by gavage on 

gestation days 6−19 (Cholakis, 1980); BMR = 1% extra risk ......................................... D-31

Table D-14. Model predictions for testicular degeneration in male B6C3F1 mice exposed to RDX 

by diet for 24 months (Lish et al., 1984); BMR = 10% extra risk................................... D-33

Table D-15. Model predictions for prostate suppurative inflammation in male F344 rats exposed 

to RDX by diet for 24 months (Levine et al., 1983); BMR = 10% extra risk................... D-36

Table D-16. Cancer endpoints selected for dose-response modeling for RDX...................................... D-39

Table D-17. Model predictions for combined alveolar/bronchiolar adenoma and carcinoma in 

female B6C3F1 mice exposed to RDX by diet for 24 months (Lish et al., 1984); 

BMR = 10% extra risk .................................................................................................... D-40

Table D-18. Model predictions for combined alveolar/bronchiolar adenoma and carcinoma in 

female B6C3F1 mice exposed to RDX by diet for 24 months (Lish et al., 1984); 

BMR = 5% extra risk ...................................................................................................... D-43

Table D-19. Model predictions for combined hepatocellular adenoma and carcinoma in female 

B6C3F1 mice exposed to RDX by diet for 24 months (Parker et al., 2006); BMR = 

10% extra risk................................................................................................................ D-45

Table D-20. Model predictions for B6C3F1 female mouse combined hepatocellular adenoma and 

carcinoma in mice exposed to RDX by diet for 24 months (Parker et al., 2006); 

BMR = 5% extra risk ...................................................................................................... D-47

Table D-21. Model predictions and oral slope factor for hepatocellular carcinomas in male F344 

rats administered RDX in the diet for 2 years (Levine et al., 1983).............................. D-52

Table D-22. Model predictions for combined hepatocellular adenoma and carcinoma in F344 

rats exposed to RDX by diet for 24 months (Levine et al., 1983); BMR = 5% extra 

risk................................................................................................................................. D-53

FIGURES 

Figure C-1. PBPK model structure for RDX in rats and humans.............................................................. C-12

Figure C-2. EPA rat PBPK model predictions fitted to observed RDX blood concentrations in male 

and female SD rats following intravenous exposure..................................................... C-17

Figure C-3. EPA rat PBPK model predictions fitted to observed RDX blood concentrations 

following oral exposure to RDX dissolved in water. ...................................................... C-20

Figure C-4. EPA rat model predictions fitted to observed RDX blood concentrations following 

oral exposure to RDX in dry capsules.. .......................................................................... C-20

Figure C-5. Effect of varying oral absorption parameters on EPA rat model predictions fitted to 

observed RDX blood concentrations following oral exposure to coarse grain 

RDX................................................................................................................................. C-21

Figure C-6. EPA rat model predictions fitted to observed RDX brain tissue concentrations 

following oral exposure to RDX.. ................................................................................... C-21

Figure C-7. EPA rat model predictions fitted to observed RDX blood concentrations following 

oral exposure to fine grain RDX in a saline slurry .......................................................... C-22

Figure C-8. Comparison of EPA rat model predictions with data from Schneider et al. (1978) for 

the subchronic gavage study. ........................................................................................ C-24

Figure C-9. Comparison of EPA rat model predictions with data from Schneider et al. (1978) for 

the subchronic drinking water study ............................................................................. C-24
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Figure C-10. EPA human model predictions fitted to observed RDX blood concentrations 

resulting from an accidental ingestion of RDX by a 14.5-kg boy (Woody et al., 

1986).............................................................................................................................. C-26

Figure C-11. EPA human model predictions fitted to observed RDX blood concentrations 

resulting from accidental exposure to adults assumed to be 70 kg (Ozhan et al., 

2003). ............................................................................................................................. C-26

Figure C-12. Comparison of EPA mouse PBPK model predictions with data from oral exposure to 

RDX dissolved in water. ................................................................................................. C-28

Figure D-1. Plot of incidence rate by dose, with fitted curve for selected model, for convulsions 

in female F344 rats exposed to RDX by gavage for 90 days (Crouse et al., 2006). ......... D-4

Figure D-2. Plot of incidence rate by dose, with fitted curve for selected model, for convulsions 

in female F344 rats exposed to RDX by gavage for 90 days (Crouse et al., 2006).......... D-7

Figure D-3. Plot of incidence rate by dose, with fitted curve for selected model, for convulsions 

in female F344 rats exposed to RDX by gavage for 90 days (Crouse et al., 2006).......... D-9

Figure D-4. Plot of incidence rate by dose, with fitted curve for selected model, for convulsions 

in male F344 rats exposed to RDX by gavage for 90 days (Crouse et al., 2006)........... D-12

Figure D-5. Plot of incidence rate by dose, with fitted curve for selected model, for convulsions 

in male F344 rats exposed to RDX by gavage for 90 days (Crouse et al., 2006)........... D-15

Figure D-6. Plot of incidence rate by dose, with fitted curve for selected model, for convulsions 

in male F344 rats exposed to RDX by gavage for 90 days (Crouse et al., 2006)........... D-17

Figure D-7. Plot of incidence rate by dose, with fitted curve for selected model, for convulsions 

in male and female F344 rats exposed to RDX by gavage for 90 days (Crouse et 

al., 2006). ...................................................................................................................... D-20

Figure D-8. Plot of incidence rate by dose, with the fitted curve of the selected model, for 

convulsions in male and female F344 rats exposed to RDX by gavage for 90 days 

(Crouse et al., 2006)...................................................................................................... D-23

Figure D-9. Plot of incidence rate by dose, with the fitted curve of the selected model, for 

convulsions in male and female F344 rats exposed to RDX by gavage for 90 days 

(Crouse et al., 2006)...................................................................................................... D-25

Figure D-10. Plot of incidence rate by dose, with the fitted curve of the selected model, for 

convulsions in female F344 rats exposed to RDX by gavage on gestation days 6–

19 (Cholakis, 1980)........................................................................................................ D-27

Figure D-11. Plot of incidence rate by dose, with the fitted curve of the selected model, for 

convulsions in female F344 rats exposed to RDX by gavage on gestation days 6–

19 (Cholakis, 1980).. ...................................................................................................... D-29

Figure D-12. Plot of incidence rate by dose, with the fitted curve of the selected model, for 

convulsions in female F344 rats exposed to RDX by gavage on gestation days 6–

19 (Cholakis, 1980)........................................................................................................ D-31

Figure D-13. Plot of incidence rate by dose, with fitted curve for selected model, for testicular 

degeneration in male B6C3F1 mice exposed to RDX by diet for 24 months (Lish et 

al., 1984) ....................................................................................................................... D-34

Figure D-14. Plot of incidence rate by dose, with fitted curve for selected model, for prostate 

suppurative inflammation in male F344 rats exposed to RDX by diet for 24 

months (Levine et al., 1983) ......................................................................................... D-37

Figure D-15. Plot of incidence rate by dose, with the fitted curve for the selected model, for 

combined alveolar/bronchiolar adenoma and carcinoma in female B6C3F1 mice 

exposed to RDX by diet for 24 months (Lish et al., 1984); BMR = 10% extra risk; 

dose shown in mg/kg-day............................................................................................. D-41
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Figure D-16. Plot of incidence rate by dose, with fitted curve for selected model, for combined 

alveolar/bronchiolar adenoma and carcinoma in female B6C3F1 mice exposed to 

RDX by diet for 24 months (Lish et al., 1984) ............................................................... D-43

Figure D-17. Plot of incidence rate by dose, with fitted curve for selected model, for combined

hepatocellular adenoma and carcinoma in female B6C3F1 mice exposed to RDX 

by diet for 24 months (Parker et al., 2006)................................................................... D-45

Figure D-18. Plot of incidence rate by dose, with fitted curve for selected model, for B6C3F1

female mouse combined hepatocellular adenoma and carcinoma in mice 

exposed to RDX by diet for 24 months (Parker et al., 2006) ........................................ D-47

Figure D-19. Plot of incidence rate by dose, with fitted curve for selected model, for combined 

hepatocellular adenoma and carcinoma in F344 rats exposed to RDX by diet for 

24 months (Levine et al., 1983) .................................................................................... D-53
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ABBREVIATIONS

ACGIH American Conference of Governmental

Industrial Hygienists 

AIC Akaike’s information criterion 

ALT alanine aminotransferase 

AST aspartate aminotransferase 

ATSDR Agency for Toxic Substances and 

Disease Registry 

AUC area under the curve

BMD benchmark dose 

BMDL benchmark dose lower confidence limit 

BMDS Benchmark Dose Software 

BMDU benchmark dose upper bound

BMR benchmark response 

BUN blood urea nitrogen 

CAS Chemical Abstracts Service 

CASRN Chemical Abstracts Service Registry 

Number 

CICADS Concise International Chemical 

Assessment Documents

CNS central nervous system 

CSF cerebrospinal fluid

CYP450 cytochrome P450 

d.f degrees of freedom

DMSO dimethylsulfoxide 

DNA deoxyribonucleic acid 

DNX 1‐nitro-3,5‐dinitroso-1,3,5‐

triazacyclohexane 

DTIC Defense Technical Information Center

EEG electroencephalography

EHC Environmental Health Criteria 

EPA Environmental Protection Agency 

ER extra risk

FDA Food and Drug Administration 

FM Fort Meade

GI gastrointestinal 

HERO Health and Environmental Research 

Online

HGPRT hypoxanthine-guanine 

phosphoribosyltransferase

HMX cyclotetramethylene-tetranitramine

i.p. intraperitoneal 

i.v. intravenous 

IARC International Agency for Research on 

Cancer

IH industrial hygiene

IPCS International Programme on Chemical 

Safety

IRIS Integrated Risk Information System 

LAAP Louisiana Army Ammunition Plant

LC50 median lethal concentration 

LD50 median lethal dose 

MNX hexahydro‐1‐nitroso‐3,5‐dinitro‐

1,3,5-triazine 

MRL Minimal Risk Level

NADPH nicotinamide adenine dinucleotide 

phosphate

NAP National Academies Press

NAS National Academy of Science

NCE normochromatic erythrocytes

NCEA National Center for Environmental 

Assessment 

NCI National Cancer Institute 

NCTR National Center for Toxicological 

Research

ND not detected

NIEHS National Institute of Environmental 

Health Sciences

NIOSHTIC National Institute for Occupational

Safety and Health Technical 

Information Center

NR not reported

NSCEP National Service Center for 

Environmental Publications

NTP National Toxicology Program 

ORD Office of Research and Development 

PBPK physiologically based pharmacokinetic 

PCE polychromatic erythrocytes

PEL permissible exposure limit

PND postnatal day

POD point of departure 

REL recommended exposure limit

ROD record of decision

SD standard deviation 

STEL short-term exposure limit

TLV threshold limit value

TNT trinitrotoluene

TNX 1,3,5-trinitroso-1,3,5-triazacyclohexane 

TSCATS Toxic Substances Control Act Test 

Submissions

TWA time-weighted average 

UF uncertainty factor

WHO World Health Organization 
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APPENDIX A. ASSESSMENTS BY OTHER NATIONAL 

AND INTERNATIONAL HEALTH AGENCIES

1 Table A-1. Assessments by Other National and International Health Agencies 

Organization Toxicity value

Agency for Toxic Substances and 

Disease Registry (ATSDR, 2012) 

Acute oral minimal risk level (MRL)—0.2 mg/kg-d

Basis: tremors and convulsions in rats (Crouse et al., 2006); 

application of a composite uncertainty factor (UF) of 30 (3 for 

extrapolation from animals to humans with dosimetric adjustments 

[PBPK modeling] and 10 for human variability)

Intermediate oral MRL—0.1 mg/kg-d 

Basis: convulsions in rats (Crouse et al., 2006); application of a 

composite UF of 30 (3 for extrapolation from animals to humans with 

dosimetric adjustments [PBPK modeling] and 10 for human 

variability)

Chronic oral MRL—0.1 mg/kg-d 

Basis: tremors and convulsions in rats (Levine et al., 1983); application 

of a composite UF of 30 (3 for extrapolation from animals to humans 

with dosimetric adjustments [PBPK modeling] and 10 for human 

variability)
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Organization Toxicity value

American Conference of 

Governmental Industrial Hygienists

(ACGIH, 2011, 2001) 

Threshold Limit Value (TLV)—0.5 mg/m3, time weighted average (TWA) 

for an 8-hr workday in a 40-hr workweek

Basis: Intended to minimize the potential for adverse hepatic, 

prostate, and hematopoietic effects reported in long-term oral 

studies in experimental animals. ACGIH documentation does not 

describe how dose-response data from oral studies was extrapolated 

to inhalation exposures, or whether other factors were applied to 

account for extrapolation of animal data to humans.

Skin notation indicates potential for systemic exposure and/or toxicity 

via dermal absorption. 

Basis: A report of five cases of RDX-exposed munition workers with 

convulsions and/or loss of consciousness in a plant where mechanical 

ventilation was absent, material handling was poorly controlled, and 

rules regarding wearing of respirators and hand-washing were often 

ignored {Kaplan, 1965, 630095}. Authors identified inhalation, 

ingestion, and possibly skin absorption as exposure routes; dermal 

exposure was not specifically documented. {ACGIH, 2001, 

630056@@author-year} acknowledged that data related to dermal

exposure and toxic effects were very limited, but that “a conservative 

approach to minimize potential toxic effects warrants inclusion of a 

skin notation for cyclonite.”

Class A4 (Not classifiable as a human carcinogen)

Basis: Statistically significantly increased incidence of hepatocellular 

adenomas and carcinomas in B6C3F1 mice {Lish, 1984, 

630027@@author-year} were determined to be of little biological 

significance.

Australian National Industrial 

Chemicals Notification and 

Assessment Scheme (NICNAS Health 

Substances Information System 

Database 

http://www.nicnas.gov.au/industry/ai

cs/search.asp, accessed May 2, 2012)

Exposure Standard—1.5 mg/m3 TWA for an 8-hr workday

Basis: adopted from the ACGIH TLV established in 1969

Skin absorption notice indicates that absorption through the skin may be 

a significant source of exposure

Basis: adopted from ACGIH

National Institute of Occupational 

Safety and Health (NIOSH Pocket 

Guide online 

http://www.cdc.gov/niosh/npg/defaul

t.html, accessed May 2, 2012)

Recommended Exposure Limit (REL)—1.5 mg/m3 TWA for up to a 10-hr 

workday during a 40-hr workweek

Basis: adopted from the ACGIH TLV established in 1969

Skin designation indicates potential for dermal absorption

Basis: adopted from ACGIH

Occupational Safety and Health (OSHA 

PEL for Maritime and Construction 

Industries; 29 CFR 1915.1000 Table ZShipyards and 29 CFR 1926.55 

Appendix A)

Permissible Exposure Limit (PEL)—1.5 mg/m3 TWA for an 8-hr workday in 

a 40-hr workweek

Basis: adopted from the ACGIH TLV established in 1969

Skin designation indicates that cutaneous exposure may contribute to 

overall exposure and measures should be taken to prevent skin 

absorption. 

Basis: adopted from ACGIH
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APPENDIX B. ADDITIONAL DETAILS OF LITERATURE 

SEARCH STRATEGY | STUDY SELECTION AND 

EVALUATION

The literature search for RDX was conducted in five online scientific databases; the most 

recent update was conducted in January, 2014. The detailed search strategy used to search four of 

these databases—Pubmed, Toxline, Toxcenter, and TSCATS—is provided in Table B-1. The search 

strategy used to search the Defense Technical Information Center (DTIC) database is described in 

Table B-2. The computerized database searches were augmented by review of online regulatory 

sources as well as “forward” and “backward” Web of Science searches of two recent reviews 

(Table B-3).

Defense Technical Information Center (DTIC) Literature Search and Screen 

Eight hundred sixty-seven RDX-related citations were identified in the DTIC database; 

510 were the full-text documents with unlimited distribution, 307 were classified as “distribution 

limited to U.S. Government agencies only,” and 50 were classified as “distribution limited to 

Department of Defense only.” Of the 867 citations, eight citations with unlimited distribution and 

10 citations with limited distribution were selected for further review. The eight citations with 

unlimited distribution (that were not duplicated in other databases) were uploaded to the Health 

and Environmental Research Online (HERO) website1 (http://hero.epa.gov). The 10 limiteddistribution citations were evaluated for pertinence to the health effects of RDX (i.e., with a focus on 

whether they provided additional primary health effects data) to determine whether EPA should 

seek authorization for public distribution and upload to HERO. A review of the abstract or full-text 

of the documents associated with the citation resulted in the following determinations:

• 4 of the 10 citations were excluded from further consideration because the reports were not 

specific to RDX, or addressed environmental properties (e.g., leaching);

• 3 of the citations were excluded because they did not provide additional primary health effects 

data. The citations either described a study plan for, or reported data from, experiments that 

 

1HERO is a database of scientific studies and other references used to develop EPA’s risk assessments aimed 

at understanding the health and environmental effects of pollutants and chemicals. It is developed and 

managed in EPA’s Office of Research and Development (ORD) by the National Center for Environmental 

Assessment (NCEA). The database includes more than 300,000 scientific articles from the peer-reviewed 

literature. New studies are added continuously to HERO. 
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1 were subsequently published (Williams et al., 2011; Hathaway and Buck, 1977) and had 

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already been identified by the literature search strategy;

• 1 citation was identified as actually having unlimited distribution (duplicate record in DTIC 

database), and was added to the HERO database (Lish et al., 1984); 

• 1 citation provided animal inhalation data and was considered pertinent, but was not brought 

forward for further review because flaws in the design of study were such that results would not 

be considered credible. These study design issues included lack of a control group, small 

numbers of animals, incomplete information on dosage or exposure levels, and inadequate 

reporting; 

• 1 citation did not have an abstract or full text available outside of the Department of Defense. 

Based on the title, this report appeared to deal specifically with the manufacture and 

chemical/explosive properties of RDX. Given the available information, it was determined that it 

was unlikely the report would provide primary health effects data that warranted further 

review. 

The rationales for exclusion of the other 849 references that were not selected for further 

consideration are summarized in Table B-4.

Disposition of Studies Kept for Further Review in July 2013 Preliminary Materials

In EPA’s 2013 Preliminary Materials for the Integrated Risk Information System (IRIS) 

Toxicological Review of Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 15 studies were identified as 

“kept for possible further review,” including papers with no abstract, inadequate information in the 

abstract, or available only in a foreign language. EPA sought input from the public on the utility of 

these studies in the development of the Toxicological Review. No public comments on the 

usefulness of these 15 papers to assessing the health effects of RDX were received at the December 

2013 bimonthly meeting discussion of the RDX preliminary materials. Upon further review, none of 

the 15 references were determined to be pertinent to an assessment of the health effects of RDX 

following chronic exposure or a source of information significantly different from other studies 

identified through the literature search. Of the 15 citations reviewed:

• 5 of the 15 references described case reports of animal poisoning. 

• 5 of the 15 articles were in a foreign language and either due to their age (published before 

1960) or title were determined not to provide additional information to substantively inform the 

toxicity of RDX. 

• 2 of the 15 references were not published in the peer-reviewed literature and did not appear to 

significantly add to other literature sources.

• 1 of the 15 references, based on limited information, appeared to be a site-specific investigation 

of poisonings that did not substantively address the chronic toxicity of RDX.
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

 B-3 DRAFT―DO NOT CITE OR QUOTE

1 • 1 of the 15 references, based on limited information, appeared to be a review/annotated 

2

3 

4 

5 

6 

7 

8 

9 

10

11

12

13

14

15

bibliography of other literature and would not significantly add to the literature already 

identified through the literature search process. 

• 1 of the 15 references was a meeting abstract.

Additional References Not Specific to RDX

During assessment development, 93 additional references were cited as sources of 

information used to help explain or clarify an issue raised in assessing the health effects of RDX, but 

were not specific to RDX and were not identified through the chemical-specific literature search 

strategies described in Figure LS-1. Other references cited in the Toxicological Review that are not 

specific to RDX include EPA guidelines and related documents. These references were tracked in 

HERO as an additional search strategy (“references added during assessment development”). For 

transparency, those articles are then automatically included as Secondary Sources of Health Effects 

Information in the overall literature search strategy. 

Table B-1. Summary of detailed search strategies for RDX (Pubmed, Toxline, 

Toxcenter, TSCATS)

Database Set # Terms Hits

PubMed

Date: 

4/2012

1A1 ((((121-82-4) OR (Cyclonite[tw] OR Cyclotrimethylenetrinitramine[tw] 

OR "cyclotrimethylene trinitramine"[tw] OR "Hexahydro-1,3,5-trinitro1,3,5-triazine"[tw] OR "Hexahydro-1,3,5-trinitro-s-triazine"[tw] OR 

Hexogen[tw] OR "1,3,5-trinitro-1,3,5-triazine"[tw] OR "1,3,5-Triaza1,3,5-trinitrocyclohexane"[tw] OR "1,3,5-Trinitro-1,3,5-

triazacyclohexane"[tw] OR "1,3,5-Trinitrohexahydro-1,3,5-triazine"[tw] 

OR "1,3,5-Trinitrohexahydro-s-triazine"[tw] OR "1,3,5-

Trinitroperhydro-1,3,5-triazine"[tw] OR "Esaidro-1,3,5-trinitro-1,3,5-

triazina"[tw] OR "Hexahydro-1,3,5-trinitro-1,3,5-triazin"[tw] OR 

"Perhydro-1,3,5-trinitro-1,3,5-triazine"[tw] OR 

Cyclotrimethylenenitramine[tw] OR Trimethylenetrinitramine[tw] OR 

"Trimethylene trinitramine"[tw] OR Trimethyleentrinitramine[tw] OR 

"Trinitrocyclotrimethylene triamine"[tw] OR 

Trinitrotrimethylenetriamine[tw] OR "CX 84A"[tw] OR Cyklonit[tw] OR 

Geksogen[tw] OR Heksogen[tw] OR Hexogeen[tw] OR Hexolite[tw] OR 

"KHP 281"[tw] OR "PBX (af) 108"[tw] OR "PBXW 108(E)"[tw] OR 

"Pbx(AF) 108"[tw]) OR (rdx[tw])) NOT medline[sb]) OR (((121-82-4) OR 

(Cyclonite[tw] OR Cyclotrimethylenetrinitramine[tw] OR 

"cyclotrimethylene trinitramine"[tw] OR "Hexahydro-1,3,5-trinitro1,3,5-triazine"[tw] OR "Hexahydro-1,3,5-trinitro-s-triazine"[tw] OR 

Hexogen[tw] OR "1,3,5-trinitro-1,3,5-triazine"[tw] OR "1,3,5-Triaza1,3,5-trinitrocyclohexane"[tw] OR "1,3,5-Trinitro-1,3,5-

triazacyclohexane"[tw] OR "1,3,5-Trinitrohexahydro-1,3,5-triazine"[tw] 

OR "1,3,5-Trinitrohexahydro-s-triazine"[tw] OR "1,3,5-

Trinitroperhydro-1,3,5-triazine"[tw] OR "Esaidro-1,3,5-trinitro-1,3,5-

triazina"[tw] OR "Hexahydro-1,3,5-trinitro-1,3,5-triazin"[tw] OR 

"Perhydro-1,3,5-trinitro-1,3,5-triazine"[tw] OR 

Cyclotrimethylenenitramine[tw] OR Trimethylenetrinitramine[tw] OR 

337
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

 B-4 DRAFT―DO NOT CITE OR QUOTE

Database Set # Terms Hits

"Trimethylene trinitramine"[tw] OR Trimethyleentrinitramine[tw] OR 

"Trinitrocyclotrimethylene triamine"[tw] OR 

Trinitrotrimethylenetriamine[tw] OR "CX 84A"[tw] OR Cyklonit[tw] OR 

Geksogen[tw] OR Heksogen[tw] OR Hexogeen[tw] OR Hexolite[tw] OR 

"KHP 281"[tw] OR "PBX (af) 108"[tw] OR "PBXW 108(E)"[tw] OR 

"Pbx(AF) 108"[tw]) OR (rdx[tw])) AND (to[sh] OR po[sh] OR ae[sh] OR 

pk[sh] OR (me[sh] AND (humans[mh] OR animals[mh])) OR ci[sh] OR 

bl[sh] OR cf[sh] OR ur[sh] OR ((pharmacokinetics[mh] OR 

metabolism[mh]) AND (humans[mh] OR mammals[mh])) OR "doseresponse relationship, drug"[mh] OR risk[mh] OR "toxicity tests"[mh] 

OR noxae[mh] OR cancer[sb] OR "endocrine system"[mh] OR 

"endocrine disruptors"[mh] OR "Hormones, Hormone Substitutes, and 

Hormone Antagonists"[mh] OR triazines/ai OR ("Inhalation 

Exposure"[Mesh] OR "Maternal Exposure"[Mesh] OR "Maximum 

Allowable Concentration"[Mesh] OR "Occupational Exposure"[Mesh] 

OR "Paternal Exposure"[Mesh] OR "Environmental 

Exposure"[Mesh:noexp])))) NOT (((((121-82-4) OR (Cyclonite[tw] OR 

Cyclotrimethylenetrinitramine[tw] OR "cyclotrimethylene 

trinitramine"[tw] OR "Hexahydro-1,3,5-trinitro-1,3,5-triazine"[tw] OR 

"Hexahydro-1,3,5-trinitro-s-triazine"[tw] OR Hexogen[tw] OR "1,3,5-

trinitro-1,3,5-triazine"[tw] OR "1,3,5-Triaza-1,3,5-

trinitrocyclohexane"[tw] OR "1,3,5-Trinitro-1,3,5-

triazacyclohexane"[tw] OR "1,3,5-Trinitrohexahydro-1,3,5-triazine"[tw] 

OR "1,3,5-Trinitrohexahydro-s-triazine"[tw] OR "1,3,5-

Trinitroperhydro-1,3,5-triazine"[tw] OR "Esaidro-1,3,5-trinitro-1,3,5-

triazina"[tw] OR "Hexahydro-1,3,5-trinitro-1,3,5-triazin"[tw] OR 

"Perhydro-1,3,5-trinitro-1,3,5-triazine"[tw] OR 

Cyclotrimethylenenitramine[tw] OR Trimethylenetrinitramine[tw] OR 

"Trimethylene trinitramine"[tw] OR Trimethyleentrinitramine[tw] OR 

"Trinitrocyclotrimethylene triamine"[tw] OR 

Trinitrotrimethylenetriamine[tw] OR "CX 84A"[tw] OR Cyklonit[tw] OR 

Geksogen[tw] OR Heksogen[tw] OR Hexogeen[tw] OR Hexolite[tw] OR 

"KHP 281"[tw] OR "PBX (af) 108"[tw] OR "PBXW 108(E)"[tw] OR 

"Pbx(AF) 108"[tw]) OR (rdx[tw])) NOT medline[sb]) OR (((121-82-4) OR 

(Cyclonite[tw] OR Cyclotrimethylenetrinitramine[tw] OR 

"cyclotrimethylene trinitramine"[tw] OR "Hexahydro-1,3,5-trinitro1,3,5-triazine"[tw] OR "Hexahydro-1,3,5-trinitro-s-triazine"[tw] OR 

Hexogen[tw] OR "1,3,5-trinitro-1,3,5-triazine"[tw] OR "1,3,5-Triaza1,3,5-trinitrocyclohexane"[tw] OR "1,3,5-Trinitro-1,3,5-

triazacyclohexane"[tw] OR "1,3,5-Trinitrohexahydro-1,3,5-triazine"[tw] 

OR "1,3,5-Trinitrohexahydro-s-triazine"[tw] OR "1,3,5-

Trinitroperhydro-1,3,5-triazine"[tw] OR "Esaidro-1,3,5-trinitro-1,3,5-

triazina"[tw] OR "Hexahydro-1,3,5-trinitro-1,3,5-triazin"[tw] OR 

"Perhydro-1,3,5-trinitro-1,3,5-triazine"[tw] OR 

Cyclotrimethylenenitramine[tw] OR Trimethylenetrinitramine[tw] OR 

"Trimethylene trinitramine"[tw] OR Trimethyleentrinitramine[tw] OR 

"Trinitrocyclotrimethylene triamine"[tw] OR 

Trinitrotrimethylenetriamine[tw] OR "CX 84A"[tw] OR Cyklonit[tw] OR 

Geksogen[tw] OR Heksogen[tw] OR Hexogeen[tw] OR Hexolite[tw] OR 

"KHP 281"[tw] OR "PBX (af) 108"[tw] OR "PBXW 108(E)"[tw] OR 
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

 B-5 DRAFT―DO NOT CITE OR QUOTE

Database Set # Terms Hits

"Pbx(AF) 108"[tw]) OR (rdx[tw])) AND (to[sh] OR po[sh] OR ae[sh] OR 

pk[sh] OR (me[sh] AND (humans[mh] OR animals[mh])) OR ci[sh] OR 

bl[sh] OR cf[sh] OR ur[sh] OR ((pharmacokinetics[mh] OR 

metabolism[mh]) AND (humans[mh] OR mammals[mh])) OR "doseresponse relationship, drug"[mh] OR risk[mh] OR "toxicity tests"[mh] 

OR noxae[mh] OR cancer[sb] OR "endocrine system"[mh] OR 

"endocrine disruptors"[mh] OR "Hormones, Hormone Substitutes, and 

Hormone Antagonists"[mh] OR triazines/ai OR ("Inhalation 

Exposure"[Mesh] OR "Maternal Exposure"[Mesh] OR "Maximum 

Allowable Concentration"[Mesh] OR "Occupational Exposure"[Mesh] 

OR "Paternal Exposure"[Mesh] OR "Environmental 

Exposure"[Mesh:noexp])))) AND (invertebrates OR aquatic organisms 

OR fish OR fishes OR amphibians OR earthworm*))

PubMed

Date limit: 

1/2012−

2/2013

1A2 (Cyclonite[tw] OR RDX[tw] OR Cyclotrimethylenetrinitramine[tw] OR 

"cyclotrimethylene trinitramine"[tw] OR "Hexahydro-1,3,5-trinitro1,3,5-triazine"[tw] OR "Hexahydro-1,3,5-trinitro-s-triazine"[tw] OR 

Hexogen[tw] OR "1,3,5-trinitro-1,3,5-triazine"[tw] OR "1,3,5-Triaza1,3,5-trinitrocyclohexane"[tw] OR "1,3,5-Trinitro-1,3,5-

triazacyclohexane"[tw] OR "1,3,5-Trinitrohexahydro-1,3,5-triazine"[tw] 

OR "1,3,5-Trinitrohexahydro-s-triazine"[tw] OR "1,3,5-

Trinitroperhydro-1,3,5-triazine"[tw] OR "Esaidro-1,3,5-trinitro-1,3,5-

triazina"[tw] OR "Hexahydro-1,3,5-trinitro-1,3,5-triazin"[tw] OR 

"Perhydro-1,3,5-trinitro-1,3,5-triazine"[tw] OR 

Cyclotrimethylenenitramine[tw] OR Trimethylenetrinitramine[tw] OR 

"Trimethylene trinitramine"[tw] OR Trimethyleentrinitramine[tw] OR 

"Trinitrocyclotrimethylene triamine"[tw] OR 

Trinitrotrimethylenetriamine[tw] OR "CX 84A"[tw] OR Cyklonit[tw] OR 

Geksogen[tw] OR Heksogen[tw] OR Hexogeen[tw] OR Hexolite[tw] OR 

"KHP 281"[tw] OR "PBX (af) 108"[tw] OR "PBXW 108(E)"[tw] OR 

"Pbx(AF) 108"[tw]) AND (("2012/01/01"[Date - MeSH] : "3000"[Date - 

MeSH]) OR ("2012/01/01"[Date - Entrez] : "3000"[Date - Entrez]) OR 

("2012/01/01"[Date - Create] : "3000"[Date - Create]))

112

PubMed

Date limit: 

11/2012−

1/2014

1A3 (Cyclonite[tw] OR RDX[tw] OR Cyclotrimethylenetrinitramine[tw] OR 

"cyclotrimethylene trinitramine"[tw] OR "Hexahydro-1,3,5-trinitro1,3,5-triazine"[tw] OR "Hexahydro-1,3,5-trinitro-s-triazine"[tw] OR 

Hexogen[tw] OR "1,3,5-trinitro-1,3,5-triazine"[tw] OR "1,3,5-Triaza1,3,5-trinitrocyclohexane"[tw] OR "1,3,5-Trinitro-1,3,5-

triazacyclohexane"[tw] OR "1,3,5-Trinitrohexahydro-1,3,5-triazine"[tw] 

OR "1,3,5-Trinitrohexahydro-s-triazine"[tw] OR "1,3,5-

Trinitroperhydro-1,3,5-triazine"[tw] OR "Esaidro-1,3,5-trinitro-1,3,5-

triazina"[tw] OR "Hexahydro-1,3,5-trinitro-1,3,5-triazin"[tw] OR 

"Perhydro-1,3,5-trinitro-1,3,5-triazine"[tw] OR 

Cyclotrimethylenenitramine[tw] OR Trimethylenetrinitramine[tw] OR 

"Trimethylene trinitramine"[tw] OR Trimethyleentrinitramine[tw] OR 

"Trinitrocyclotrimethylene triamine"[tw] OR 

Trinitrotrimethylenetriamine[tw] OR "CX 84A"[tw] OR Cyklonit[tw] OR 

Geksogen[tw] OR Heksogen[tw] OR Hexogeen[tw] OR Hexolite[tw] OR 

"KHP 281"[tw] OR "PBX (af) 108"[tw] OR "PBXW 108(E)"[tw] OR 

"Pbx(AF) 108"[tw]) AND (("2012/11/01"[Date - MeSH] : "3000"[Date -

138
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

 B-6 DRAFT―DO NOT CITE OR QUOTE

Database Set # Terms Hits

MeSH]) OR ("2012/11/01"[Date - Entrez] : "3000"[Date - Entrez]) OR 

("2012/11/01"[Date - Create] : "3000"[Date - Create]))

Toxline

Date: 

4/2012

1B1 Notes: Searched CASRN or synonyms;

-removed invertebrates, aquatic organisms, amphibians, earthworms

507

Toxline

Date limit: 

2011−

2/2013

1B2 @OR+("Cyclonite"+"RDX"+"Cyclotrimethylenetrinitramine"+"cyclotrim

ethylene trinitramine"+"Hexahydro-1,3,5-trinitro-1,3,5-

triazine"+"Hexahydro-1,3,5-trinitro-s-triazine"+"Hexogen"+"1,3,5-

trinitro-1,3,5-triazine"+"1,3,5-Triaza-1,3,5-trinitrocyclohexane"+"1,3,5-

Trinitro-1,3,5-triazacyclohexane"+"1,3,5-Trinitrohexahydro-1,3,5-

triazine"+"1,3,5-Trinitrohexahydro-s-triazine"+@term+@rn+121-82-

4)+@AND+@range+yr+2011+2013+@NOT+@org+pubmed+pubdart+cr

isp+tscats

5

1B3 @OR+("1,3,5-Trinitroperhydro-1,3,5-triazine"+"Esaidro-1,3,5-trinitro1,3,5-triazina"+"Hexahydro-1,3,5-trinitro-1,3,5-triazin"+"Perhydro1,3,5-trinitro-1,3,5-

triazine"+"Cyclotrimethylenenitramine"+"Trimethylenetrinitramine"+"

Trimethylene+trinitramine"+"Trimethyleentrinitramine"+"Trinitrocyclo

trimethylene+triamine"+"Trinitrotrimethylenetriamine"+"CX+84A"+"Cy

klonit"+"Geksogen"+"Heksogen"+"Hexogeen"+"Hexolite"+"KHP+281")

+@AND+@range+yr+2011+2013+@NOT+@org+pubmed+pubdart+cris

p+tscats

0

Toxline

Date limit: 

2012−

1/2014

1B4 @OR+("Cyclonite"+"RDX"+"Cyclotrimethylenetrinitramine"+"cyclotrim

ethylene trinitramine"+"Hexahydro-1,3,5-trinitro-1,3,5-

triazine"+"Hexahydro-1,3,5-trinitro-s-triazine"+"Hexogen"+"1,3,5-

trinitro-1,3,5-triazine"+"1,3,5-Triaza-1,3,5-trinitrocyclohexane"+"1,3,5-

Trinitro-1,3,5-triazacyclohexane"+"1,3,5-Trinitrohexahydro-1,3,5-

triazine"+"1,3,5-Trinitrohexahydro-s-triazine"+@term+@rn+121-82-

4)+@AND+@range+yr+2012+2014+@NOT+@org+pubmed+pubdart+cr

isp+tscats

10

1B5 @OR+("1,3,5-Trinitroperhydro-1,3,5-triazine"+"Esaidro-1,3,5-trinitro1,3,5-triazina"+"Hexahydro-1,3,5-trinitro-1,3,5-triazin"+"Perhydro1,3,5-trinitro-1,3,5-

triazine"+"Cyclotrimethylenenitramine"+"Trimethylenetrinitramine"+"

Trimethylene+trinitramine"+"Trimethyleentrinitramine"+"Trinitrocyclo

trimethylene+triamine"+"Trinitrotrimethylenetriamine"+"CX+84A"+"Cy

klonit"+"Geksogen"+"Heksogen"+"Hexogeen"+"Hexolite"+"KHP+281")

+@AND+@range+yr+2012+2014+@NOT+@org+pubmed+pubdart+cris

p+tscats

0

TSCATS

Date: 

2/2013

1C1 @term+@rn+121-82-4+@AND+@org+tscats 4

TSCATS

Date limit: 

2012−

1/2014

1C2 @OR+(@term+@rn+121-82-

4)+@AND+@range+yr+2012+2014+@AND+@org+tscats

0
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

 B-7 DRAFT―DO NOT CITE OR QUOTE

Database Set # Terms Hits

Toxcenter

Date: 

4/2012

1D1 ((121-82-4 OR Cyclonite OR RDX OR Cyclotrimethylenetrinitramine OR 

"cyclotrimethylene trinitramine" OR "Hexahydro-1,3,5-trinitro-1,3,5-

triazine" OR "Hexahydro-1,3,5-trinitro-s-triazine" OR Hexogen OR 

"1,3,5-trinitro-1,3,5-triazine" OR "1,3,5-Triaza-1,3,5-

trinitrocyclohexane" OR "1,3,5-Trinitro-1,3,5-triazacyclohexane" OR 

"1,3,5-Trinitrohexahydro-1,3,5-triazine" OR "1,3,5-Trinitrohexahydro-striazine" OR "1,3,5-Trinitroperhydro-1,3,5-triazine" OR "Esaidro-1,3,5-

trinitro-1,3,5-triazina" OR "Hexahydro-1,3,5-trinitro-1,3,5-triazin" OR 

"Perhydro-1,3,5-trinitro-1,3,5-triazine" OR Cyclotrimethylenenitramine 

OR Trimethylenetrinitramine OR "Trimethylene trinitramine" OR 

Trimethyleentrinitramine OR "Trinitrocyclotrimethylene triamine" OR 

Trinitrotrimethylenetriamine OR "CX 84A" OR Cyklonit OR Geksogen 

OR Heksogen OR Hexogeen OR Hexolite OR "KHP 281" OR "PBX (af) 

108" OR "PBXW 108(E)" OR "Pbx(AF) 108") NOT (patent/dt OR 

tscats/fs))AND ((chronic OR immunotox? OR neurotox? OR toxicokin? 

OR biomarker? OR neurolog? OR pharmacokin? OR subchronic OR 

pbpk OR epidemiology/st,ct,it) OR acute OR subacute OR ld50# OR 

lc50# OR (toxicity OR adverse OR poisoning)/st,ct,it OR inhal? OR 

pulmon? OR nasal? OR lung? OR respir? OR occupation? OR 

workplace? OR worker? OR oral OR orally OR ingest? OR gavage? OR 

diet OR diets OR dietary OR drinking(w)water OR (maximum and 

concentration? and (allowable OR permissible)) OR (abort? OR 

abnormalit? OR embryo? OR cleft? OR fetus? OR foetus? OR fetal? OR 

foetal? OR fertil? OR malform? OR ovum OR ova OR ovary OR 

placenta? OR pregnan? OR prenatal OR perinatal? OR postnatal? OR 

reproduc? OR steril? OR teratogen? OR sperm OR spermac? OR 

spermag? OR spermati? OR spermas? OR spermatob? OR spermatoc? 

OR spermatog? OR spermatoi? OR spermatol? OR spermator? OR 

spermatox? OR spermatoz? OR spermatu? OR spermi? OR spermo? OR 

neonat? OR newborn OR development OR developmental? OR zygote? 

OR child OR children OR adolescen? OR infant OR wean? OR offspring 

OR age(w)factor? OR dermal? OR dermis OR skin OR epiderm? OR 

cutaneous? OR carcinog? OR cocarcinog? OR cancer? OR precancer? 

OR neoplas? OR tumor? OR tumour? OR oncogen? OR lymphoma? OR 

carcinom? OR genetox? OR genotox? OR mutagen? OR 

genetic(w)toxic? OR nephrotox? OR hepatotox? OR endocrin? OR 

estrogen? OR androgen? OR hormon? OR rat OR rats OR mouse OR 

mice OR muridae OR dog OR dogs OR rabbit? OR hamster? OR pig OR 

pigs OR swine OR porcine OR goat OR goats OR sheep OR monkey? OR 

macaque? OR marmoset? OR primate? OR mammal? OR ferret? OR 

gerbil? OR rodent? OR lagomorpha OR baboon? OR bovine OR canine 

OR cat OR cats OR feline OR pigeon? OR occupation? OR worker? OR 

epidem?) AND ((biosis/fs AND py>1999) OR caplus/fs))

Notes: Duplicates were removed; Biosis subfile results were date 

limited to avoid extensive overlap with Toxline

337 (20 selected 

and added to 

HERO)

Toxcenter 

Date limit:

1D2 (((121-82-4 OR Cyclonite OR RDX OR Cyclotrimethylenetrinitramine OR 

"cyclotrimethylene trinitramine" OR "Hexahydro-1,3,5-trinitro-1,3,5-

triazine" OR "Hexahydro-1,3,5-trinitro-s-triazine" OR Hexogen OR 

"1,3,5-trinitro-1,3,5-triazine" OR "1,3,5-Triaza-1,3,5-

26 (6 selected and 

added to HERO)
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

 B-8 DRAFT―DO NOT CITE OR QUOTE

Database Set # Terms Hits

1/1/2012−

2/2013

trinitrocyclohexane" OR "1,3,5-Trinitro-1,3,5-triazacyclohexane" OR 

"1,3,5-Trinitrohexahydro-1,3,5-triazine" OR "1,3,5-Trinitrohexahydro-striazine" OR "1,3,5-Trinitroperhydro-1,3,5-triazine" OR "Esaidro-1,3,5-

trinitro-1,3,5-triazina" OR "Hexahydro-1,3,5-trinitro-1,3,5-triazin" OR 

"Perhydro-1,3,5-trinitro-1,3,5-triazine" OR Cyclotrimethylenenitramine 

OR Trimethylenetrinitramine OR "Trimethylene trinitramine" OR 

Trimethyleentrinitramine OR "Trinitrocyclotrimethylene triamine" OR 

Trinitrotrimethylenetriamine OR "CX 84A" OR Cyklonit OR Geksogen 

OR Heksogen OR Hexogeen OR Hexolite OR "KHP 281" OR "PBX (af) 

108" OR "PBXW 108(E)" OR "Pbx(AF) 108") NOT (patent/dt OR 

tscats/fs)) AND (py>2012 OR ed>20120101)) AND (chronic OR 

immunotox? OR neurotox? OR toxicokin? OR biomarker? OR neurolog? 

OR pharmacokin? OR subchronic OR pbpk OR epidemiology/st,ct, it) OR 

acute OR subacute OR ld50# OR lc50# OR (toxicity OR adverse OR 

poisoning)/st,ct,it OR inhal? OR pulmon? OR nasal? OR lung? OR 

respir? OR occupation? OR workplace? OR worker? OR oral OR orally 

OR ingest? OR gavage? OR diet OR diets OR dietary OR 

drinking(w)water OR (maximum and concentration? and (allowable OR 

permissible)) OR (abort? OR abnormalit? OR embryo? OR cleft? OR 

fetus? OR foetus? OR fetal? OR foetal? OR fertil? OR malform? OR 

ovum OR ova OR ovary OR placenta? OR pregnan? OR prenatal OR 

perinatal? OR postnatal? OR reproduc? OR steril? OR teratogen? OR 

sperm OR spermac? OR spermag? OR spermati? OR spermas? OR 

spermatob? OR spermatoc? OR spermatog? OR spermatoi? OR 

spermatol? OR spermator? OR spermatox? OR spermatoz? OR 

spermatu? OR spermi? OR spermo? OR neonat? OR newborn OR 

development OR developmental? OR zygote? OR child OR children OR 

adolescen? OR infant OR wean? OR offspring OR age(w)factor? OR 

dermal? OR dermis OR skin OR epiderm? OR cutaneous? OR carcinog? 

OR cocarcinog? OR cancer? OR precancer? OR neoplas? OR tumor? OR 

tumour? OR oncogen? OR lymphoma? OR carcinom? OR genetox? OR 

genotox? OR mutagen? OR genetic(w)toxic? OR nephrotox? OR 

hepatotox? OR endocrin? OR estrogen? OR androgen? OR hormon? OR 

rat OR rats OR mouse OR mice OR muridae OR dog OR dogs OR rabbit? 

OR hamster? OR pig OR pigs OR swine OR porcine OR goat OR goats OR 

sheep OR monkey? OR macaque? OR marmoset? OR primate? OR 

mammal? OR ferret? OR gerbil? OR rodent? OR lagomorpha OR 

baboon? OR bovine OR canine OR cat OR cats OR feline OR pigeon? OR 

occupation? OR worker? OR epidem?) AND (biosis/fs OR caplus/fs))

Notes: Duplicates were removed
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

 B-9 DRAFT―DO NOT CITE OR QUOTE

Database Set # Terms Hits

Toxcenter 

Date limit:

11/1/2012−

1/2014

1D3 (((121-82-4 OR Cyclonite OR RDX OR Cyclotrimethylenetrinitramine OR 

"cyclotrimethylene trinitramine" OR "Hexahydro-1,3,5-trinitro-1,3,5-

triazine" OR "Hexahydro-1,3,5-trinitro-s-triazine" OR Hexogen OR 

"1,3,5-trinitro-1,3,5-triazine" OR "1,3,5-Triaza-1,3,5-

trinitrocyclohexane" OR "1,3,5-Trinitro-1,3,5-triazacyclohexane" OR 

"1,3,5-Trinitrohexahydro-1,3,5-triazine" OR "1,3,5-Trinitrohexahydro-striazine" OR "1,3,5-Trinitroperhydro-1,3,5-triazine" OR "Esaidro-1,3,5-

trinitro-1,3,5-triazina" OR "Hexahydro-1,3,5-trinitro-1,3,5-triazin" OR 

"Perhydro-1,3,5-trinitro-1,3,5-triazine" OR Cyclotrimethylenenitramine 

OR Trimethylenetrinitramine OR "Trimethylene trinitramine" OR 

Trimethyleentrinitramine OR "Trinitrocyclotrimethylene triamine" OR 

Trinitrotrimethylenetriamine OR "CX 84A" OR Cyklonit OR Geksogen 

OR Heksogen OR Hexogeen OR Hexolite OR "KHP 281" OR "PBX (af) 

108" OR "PBXW 108(E)" OR "Pbx(AF) 108") NOT (patent/dt OR 

tscats/fs)) AND (py>2012 OR ed>20121101)) AND (chronic OR 

immunotox? OR neurotox? OR toxicokin? OR biomarker? OR neurolog? 

OR pharmacokin? OR subchronic OR pbpk OR epidemiology/st,ct, it) OR 

acute OR subacute OR ld50# OR lc50# OR (toxicity OR adverse OR 

poisoning)/st,ct,it OR inhal? OR pulmon? OR nasal? OR lung? OR 

respir? OR occupation? OR workplace? OR worker? OR oral OR orally 

OR ingest? OR gavage? OR diet OR diets OR dietary OR 

drinking(w)water OR (maximum and concentration? and (allowable OR 

permissible)) OR (abort? OR abnormalit? OR embryo? OR cleft? OR 

fetus? OR foetus? OR fetal? OR foetal? OR fertil? OR malform? OR 

ovum OR ova OR ovary OR placenta? OR pregnan? OR prenatal OR 

perinatal? OR postnatal? OR reproduc? OR steril? OR teratogen? OR 

sperm OR spermac? OR spermag? OR spermati? OR spermas? OR 

spermatob? OR spermatoc? OR spermatog? OR spermatoi? OR 

spermatol? OR spermator? OR spermatox? OR spermatoz? OR 

spermatu? OR spermi? OR spermo? OR neonat? OR newborn OR 

development OR developmental? OR zygote? OR child OR children OR 

adolescen? OR infant OR wean? OR offspring OR age(w)factor? OR 

dermal? OR dermis OR skin OR epiderm? OR cutaneous? OR carcinog? 

OR cocarcinog? OR cancer? OR precancer? OR neoplas? OR tumor? OR 

tumour? OR oncogen? OR lymphoma? OR carcinom? OR genetox? OR 

genotox? OR mutagen? OR genetic(w)toxic? OR nephrotox? OR 

hepatotox? OR endocrin? OR estrogen? OR androgen? OR hormon? OR 

rat OR rats OR mouse OR mice OR muridae OR dog OR dogs OR rabbit? 

OR hamster? OR pig OR pigs OR swine OR porcine OR goat OR goats OR 

sheep OR monkey? OR macaque? OR marmoset? OR primate? OR 

mammal? OR ferret? OR gerbil? OR rodent? OR lagomorpha OR 

baboon? OR bovine OR canine OR cat OR cats OR feline OR pigeon? OR 

occupation? OR worker? OR epidem?) AND (biosis/fs OR caplus/fs))

Notes: Duplicates were removed

20 (0 selected)

1 
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1 Table B-2. Summary of detailed search strategies for RDX (DTIC)

Database Set # Terms Hits

DTIC Online 

Access 

Controlled

Date:

2/11/2013

2A1 key:((toxicity OR phramacokinetics OR toxicology OR pharmacology OR 

poisoning OR toxic hazards OR radiation hazards OR radiation effects OR 

toxic diseases OR toxic agents OR lethal agents OR antidotes OR death 

OR "signs and symptoms" OR cancer OR carinogens OR physiology OR 

biochemistry OR body weight OR anatomy OR body fluids OR 

metabolism OR immunology OR mutagens OR teratogenic compounds 

OR mutations OR antimetabolites) NOT (aquatic animals OR 

Invertebrates OR venomous animals OR wildlife OR biodegradation)) and 

("121-82-4" OR Cyclonite OR RDX OR Cyclotrimethylenetrinitramine OR 

"cyclotrimethylene trinitramine" OR "Hexahydro-1,3,5-trinitro-1,3,5-

triazine" OR "Hexahydro-1,3,5-trinitro-s-triazine" OR Hexogen OR 

Cyclotrimethylenenitramine OR Trimethylenetrinitramine OR 

"Trimethylene trinitramine" OR Trimethyleentrinitramine OR 

"Trinitrocyclotrimethylene triamine" OR Trinitrotrimethylenetriamine OR 

Hexolite ) and distco:(A) | Report Date: All dates

504

(8 selected and 

added to HERO)

2A2 distco:(govt) and key:((toxicity OR phramacokinetics OR toxicology OR 

pharmacology OR poisoning OR toxic hazards OR radiation hazards OR 

radiation effects OR toxic diseases OR toxic agents OR lethal agents OR 

antidotes OR death OR "signs and symptoms" OR cancer OR carinogens 

OR physiology OR biochemistry OR body weight OR anatomy OR body 

fluids OR metabolism OR immunology OR mutagens OR teratogenic 

compounds OR mutations OR antimetabolites) NOT (aquatic animals OR 

Invertebrates OR venomous animals OR wildlife OR biodegradation)) and 

("121-82-4" OR Cyclonite OR RDX OR Cyclotrimethylenetrinitramine OR 

"cyclotrimethylene trinitramine" OR "Hexahydro-1,3,5-trinitro-1,3,5-

triazine" OR "Hexahydro-1,3,5-trinitro-s-triazine" OR Hexogen OR 

Cyclotrimethylenenitramine OR Trimethylenetrinitramine OR 

"Trimethylene trinitramine" OR Trimethyleentrinitramine OR 

"Trinitrocyclotrimethylene triamine" OR Trinitrotrimethylenetriamine OR 

Hexolite ) | Report Date: All dates

304

(7 selected for 

further 

consideration)

2A3 distco:(dod) and key:((toxicity OR phramacokinetics OR toxicology OR 

pharmacology OR poisoning OR toxic hazards OR radiation hazards OR 

radiation effects OR toxic diseases OR toxic agents OR lethal agents OR 

antidotes OR death OR "signs and symptoms" OR cancer OR carinogens 

OR physiology OR biochemistry OR body weight OR anatomy OR body 

fluids OR metabolism OR immunology OR mutagens OR teratogenic 

compounds OR mutations OR antimetabolites) NOT (aquatic animals OR 

Invertebrates OR venomous animals OR wildlife OR biodegradation)) and 

("121-82-4" OR Cyclonite OR RDX OR Cyclotrimethylenetrinitramine OR 

"cyclotrimethylene trinitramine" OR "Hexahydro-1,3,5-trinitro-1,3,5-

triazine" OR "Hexahydro-1,3,5-trinitro-s-triazine" OR Hexogen OR 

Cyclotrimethylenenitramine OR Trimethylenetrinitramine OR 

"Trimethylene trinitramine" OR Trimethyleentrinitramine OR 

"Trinitrocyclotrimethylene triamine" OR Trinitrotrimethylenetriamine OR 

Hexolite ) | Report Date: All dates

50

(3 selected for 

further 

consideration)
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 B-11 DRAFT―DO NOT CITE OR QUOTE

Database Set # Terms Hits

DTIC R&E 

Gateway 

Search 

Date limit: 

11/1/2012−

1/23/2014

2B1 ((toxicity OR phramacokinetics OR toxicology OR pharmacology OR 

poisoning OR toxic hazards OR radiation hazards OR radiation effects OR 

toxic diseases OR toxic agents OR lethal agents OR antidotes OR death 

OR "signs and symptoms" OR cancer OR carinogens OR physiology OR

biochemistry OR body weight OR anatomy OR body fluids OR 

metabolism OR immunology OR mutagens OR teratogenic compounds 

OR mutations OR antimetabolites) NOT (aquatic animals OR 

Invertebrates OR venomous animals OR wildlife OR biodegradation)) and 

("121-82-4" OR Cyclonite OR RDX OR Cyclotrimethylenetrinitramine OR 

"cyclotrimethylene trinitramine" OR "Hexahydro-1,3,5-trinitro-1,3,5-

triazine" OR "Hexahydro-1,3,5-trinitro-s-triazine" OR Hexogen OR 

Cyclotrimethylenenitramine OR Trimethylenetrinitramine OR 

"Trimethylene trinitramine" OR Trimethyleentrinitramine OR 

"Trinitrocyclotrimethylene triamine" OR Trinitrotrimethylenetriamine OR 

Hexolite )

Notes: Date limited to items created after October 31,2012.

Searched all distribution limits individually: 6 results found in "approved 

for public release", 3 results found in "Gov't and Gov't contractors only"

9 (0 selected)

1 Table B-3. Processes used to augment the search of core databases for RDX

Selected Key Reference(s) or Sources Date

Additional References 

Identified

Sweeney, LM; Gut, CP, Jr.; Gargas, ML; Reddy, G; Williams, LR; 

Johnson, MS. (2012a). Assessing the non-cancer risk for RDX 

(hexahydro-1,3,5-trinitro-1,3,5-triazine) using physiologically based 

pharmacokinetic (PBPK) modeling. Regul Toxicol Pharmacol 

62(1):107−114. (forward search)

1 search result

3/2013 0 citations added

Sweeney, LM; Okolica, MR; Gut, CP, Jr; Gargas, ML. (2012b). Cancer 

mode of action, weight of evidence, and proposed cancer reference 

value for hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Regul Toxicol 

Pharmacol 64(2):205−224 (backwards search)

0 search results

3/2013 0 citations added

Sweeney, LM; Gut, CP, Jr.; Gargas, ML; Reddy, G; Williams, LR; 

Johnson, MS. (2012a). Assessing the non-cancer risk for RDX 

(hexahydro-1,3,5-trinitro-1,3,5-triazine) using physiologically based 

pharmacokinetic (PBPK) modeling. Regul Toxicol Pharmacol 

62(1):107−114.

35 cited papers

3/2013 0 citations added

Sweeney, LM; Okolica, MR; Gut, CP, Jr; Gargas, ML. (2012b). Cancer 

mode of action, weight of evidence, and proposed cancer reference 

value for hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Regul Toxicol 

Pharmacol 64(2):205−224

69 cited papers

3/2013 3 citations added
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 B-12 DRAFT―DO NOT CITE OR QUOTE

Selected Key Reference(s) or Sources Date

Additional References 

Identified

Combination of CASRN and synonyms searched on the following 

websites:

ATSDR http://www.atsdr.cdc.gov/substances/index.asp

(Note: the reference list for the ATSDR toxicological profile for RDX 

was compared to the search results and relevant references were 

added)

CalEPA (Office of Environmental Health Hazard Assessment) 

(http://www.oehha.ca.gov/risk.html) 

eChemPortal

(http://www.echemportal.org/echemportal/participant/page.action?

pageID=9) 

EPA Acute Exposure Guideline Levels 

(http://www.epa.gov/oppt/aegl/pubs/chemlist.htm) 

EPA − IRISTrack/New Assessments and Reviews

(http://cfpub.epa.gov/ncea/iristrac/) to find dates

(http://www.epa.gov/ncea/iris/index.html) to find data

EPA NSCEP 

(http://www.epa.gov/ncepihom/) 

EPA Science Inventory

(http://cfpub.epa.gov/si/) 

Federal Docket 

www.regulations.gov

Health Canada First Priority List Assessments

(http://www.hc-sc.gc.ca/ewh-semt/pubs/contaminants/psl1-

lsp1/index-eng.php) 

Health Canada Second Priority List Assessments

(http://www.hc-sc.gc.ca/ewh-semt/pubs/contaminants/psl2-

lsp2/index-eng.php) 

IARC 

(http://monographs.iarc.fr/htdig/search.html) 

IPCS INCHEM 

(http://www.inchem.org/) 

NAS 

via NAP (http://www.nap.edu/) 

NCI

(http://www.cancer.gov) 

NCTR 

(http://www.fda.gov/AboutFDA/CentersOffices/OC/OfficeofScientific

andMedicalPrograms/NCTR/default.htm) 

National Institute for Environmental Health Sciences (NIEHS)

http://www.niehs.nih.gov/

NIOSHTIC 2 

(http://www2a.cdc.gov/nioshtic-2/) 

NTP − RoC, status, results, and management reports 

(http://ntpsearch.niehs.nih.gov/query.html) 

WHO assessments − CICADS, EHC

(http://www.who.int/ipcs/assessment/en/)

4/11/2012

1/27/2014

15 citations added

1 citation added

1 
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 B-13 DRAFT―DO NOT CITE OR QUOTE

1 Table B-4. Summary disposition of DTIC database citations

Criteria Percent of citations 

Exclusion—Not chemical-specific ~50%

Exclusion—Bioremediation or biodegradation 5%

Exclusion—Chemical/physical properties of explosive properties <5%

Exclusion—Physical or chemical treatment <5%

Exclusion—Miscellaneous, including:

• Superfund RODs for which the abstract did not specify whether RDX was 

a contaminant of concern

• Meeting minutes and conference proceedings for which only general 

categories of topics were included in the DTIC record

• DTIC records containing only a title containing inadequate information 

with which to classify the citation

~35%

Exclusion Total 98% (847 total)

Additional Resource—Regulatory documents <5%

Additional Resource—Reviews <5%

Additional Resource—Ecosystem effects <5%

Additional Resource—Risk assessments <5%

Additional Resource—Exposure levels <5%

Additional Resource—Measurement methods <5%

Additional Resource—Mixture only <5%

Additional Resource—Toxicokinetics <5%

Possible Further Review—No abstract <5%

Possible Further Review—inadequate reporting in abstract <5%

Inclusion Total ~2% (20 total)

TOTAL NUMBER OF DTICS CITATIONS (including 10 limited distribution for 

further review)

867

2 
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 C-1 DRAFT―DO NOT CITE OR QUOTE

1 

APPENDIX C. INFORMATION IN SUPPORT OF 

HAZARD IDENTIFICATION AND DOSE-RESPONSE 

ANALYSIS

2 C.1. CHEMICAL PROPERTIES

Table C-1. Chemical identity and physicochemical properties of RDX

Characteristic or property Value Reference

Chemical structure NLM, 2011

CASRN 121-82-4

Color/form White, crystalline solid Bingham et al. (2001)

Molecular formula C3H6N6O6 ACGIH (2001)

Molecular weight 222.12 Lide (2005)

Density (g/cm3 at 20°C) 1.82 Lide (2005)

Melting point (°C) 205.5 Lide (2005)

Heat of formation (kJ/g) −0.277 MG et al. (1984)

Log KOW 0.87−0.90 Hansch et al. (1995)

KOC 42−167 Spanggord et al. (1980)

Boiling point (°C) 276−280 Bingham et al. (2001)

Henry’s law constant 

(atm-m3/mole at 25°C)

2.0 × 10−1 U.S. EPA (2003)

Solubility in water (mg/L at 

25°C)

59.7 Yalkowsky and He (2003)

Vapor pressure (mm Hg at 20°C) 4.10 × 10−9 Spanggord et al. (1980)
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 C-2 DRAFT―DO NOT CITE OR QUOTE

1 C.2. TOXICOKINETICS

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RDX is absorbed following exposure by inhalation and oral routes. The rate and extent of 

absorption are dependent upon the dosing preparation. RDX is systemically distributed, can be 

transfered from mother to fetus and can transfer in maternal milk. Metabolism of RDX is extensive 

and includes denitration, ring cleavage, and generation of CO2 possibly through cytochrome P450 

(CYP450). RDX metabolites are eliminated primarily via urinary excretion and exhalation of CO2.

C.2.1. Absorption

Absorption of RDX following oral exposure has been demonstrated in humans and 

laboratory animals (rats, mice, swine, and voles) through measurement of radiolabeled RDX and/or 

metabolites in excreta (urine and expired air) and tissues (including blood). Quantitative estimates 

of oral absorption (e.g., oral bioavailability or fractional absorption) are not available in humans. 

Results of animals studies indicate that oral bioavailability ranges from approximately 50−90% and 

may vary based on the physical form of RDX and the matrix (e.g., soil, plants) in which it is 

administered. Studies investigating absorption of RDX following inhalation exposure were not 

identified. Results of an intratracheal administration study in rats provide limited evidence of 

absorption of RDX from the respiratory tract. The only data evaluating dermal absorption of RDX is 

provided by in vitro studies showing that RDX can be absorbed through excised skin of humans and 

animals. 

Oral Absorption

Quantitative information on blood levels following accidental exposure to RDX is limited to 

two studies of accidental oral exposures (Küçükardali et al., 2003; Woody et al., 1986) and one 

study of mixed dermal and inhalation exposure (Ozhan et al., 2003). A number of qualitative case 

studies of accidental exposures with similar toxic effects provide additional support that RDX is 

absorbed into the body (Hett and Fichtner, 2002; Harrell-Bruder and Hutchins, 1995; Goldberg et 

al., 1992; Ketel and Hughes, 1972; Hollander and Colbach, 1969; Stone et al., 1969). The oral 

absorption of RDX in humans was demonstrated in a case report of a 3-year-old male child who 

ingested plasticized RDX material that adhered to his mother’s work boots and clothing (Woody et 

al., 1986). RDX was measured in serum, urine, cerebrospinal fluid, and feces. Based on a kinetic 

analysis of the serum RDX concentrations, the dose was estimated to be 85 mg/kg and the firstorder absorption rate constants were estimated to be 0.34−2.20 hour−1 (Woody et al., 1986)2. 

Sweeney et al. (2012a) estimated the absorption rate constant for this same subject to be 

0.060 hour−1. The large range in the calculated absorption rate constants resulted from uncertainty 

in the dose and time to peak serum RDX levels, and the models that were used to simulate the RDX 

toxicokinetics. Ozhan et al. (2003) summarized plasma RDX levels in five military personnel who 

 

2Woody et al. (1986) reported the absorption rate constants in units of L/hour; however, this appears to have 

been a typographical error for 1/hour or hour−1. 
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 C-3 DRAFT―DO NOT CITE OR QUOTE

1 were accidentally exposed to toxic levels of RDX. Although Ozhan et al. (2003) reported that 

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personnel were exposed through dermal and inhaled routes, secondary oral exposure may have 

occurred. Based on PBPK model fits to the plasma RDX concentration data, Sweeney et al. (2012a)

estimated a first-order absorption rate constant of 0.033 hour−1. Küçükardali et al. (2003)

summarized plasma RDX levels in five military personnel who ingested toxic levels of RDX (doses 

were not reported). RDX was detected in plasma of all patients within 3 hours after ingestion. 

Quantitative data to directly support estimates of oral bioavailability are available from 

studies in rats and mice (Guo et al., 1985; Schneider et al., 1978, 1977). Results of single and 

repeated oral dose studies in adult Sprague-Dawley rats indicate that approximately 83−87% of the 

administered dose is absorbed from the gastrointestinal (GI) tract. Following gavage 

administration of 50 mg/kg [14C]-RDX dissolved in dimethylsulfoxide (DMSO), approximately 90% 

of the administered carbon-14 was recovered 4 days after dosing, with ~3% in feces, 34% in urine, 

43% in expired air, and 10% in the carcass (Schneider et al., 1977). It is unclear if the carcass 

includes the GI tract, which may include unabsorbed RDX. Assuming that all of the carbon-14 in 

feces represents unabsorbed RDX (rather than RDX that was absorbed and subsequently secreted 

into the intestine), results of this study indicate that at least 87% of the administered dose was 

absorbed from the GI tract. Similar results were observed following repeated daily oral exposure of 

Sprague-Dawley rats to [14C]-RDX by gavage (in DMSO) or drinking water for 1 week. Based on 

recovery of carbon-14 in urine and expired air and the carbon-14 retained in carcass, 

approximately 83% (drinking water) to 85 % (gavage) of the administered dose was absorbed

(Schneider et al., 1978). 

An estimate of oral bioavailability in rats can also be obtained from data on blood RDX 

concentrations reported in Krishnan et al. (2009). Male Sprague-Dawley rats received a single 

intravenous (i.v.) (0.77 or 1.04 mg/kg) or oral (1.53 or 2.07 mg/kg, dissolved in water) dose of RDX. 

Estimates of bioavailability were obtained based on the reported blood RDX concentrations, 

terminal elimination rate constants (estimated for this review by fitting the serum RDX data with a 

first-order exponential function, see Table C-4 in the Elimination section below) and the blood area 

under the curve (AUC) values (calculated for this review using the trapezoid rule extrapolated to 

infinite time). Calculated dose-adjusted AUC values were 9.6 and 8.4 hours-kg/L for the i.v. studies 

and 4.7 and 6.0 hours-kg/L for the oral dosing studies. These AUC values correspond to estimated 

oral bioavailability ranging from 50 to 70%. Recovery of administered radiolabel was incomplete 

(~90% of the administered carbon-14) in the studies (Schneider et al., 1978, 1977); therefore, it is 

possible that oral bioavailability is actually higher than 83−87%. Guo et al. (1985) reported data on 

blood tritium kinetics in mice that received i.v. (0.055 mg RDX or ~2.5 mg/kg body weight) or oral 

doses (50 mg/kg) of [3H]-RDX. Based on the reported blood tritium concentrations (% of dose/g) 

and terminal t1/2 values for concentrations of tritium in blood (1.1 days for i.v. and 2.2 days for 

oral), the corresponding AUCs of the blood concentration versus time curves were calculated 

(calculated for this review using the trapezoid rule extrapolated to infinite time) to be 30 and 
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 C-4 DRAFT―DO NOT CITE OR QUOTE

1 16 hours-% dose/g for i.v. and oral dosing, respectively. This corresponds to an oral bioavailability 

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of RDX-derived tritium concentration of approximately 50% (i.e., 16/30). 

In Yucatan miniature swine administered a single dose of [14C]-RDX (43−45 mg/kg as a 

suspension in carboxymethylcellulose), approximately 0.8−6% of the administered carbon-14 was 

eliminated in feces 24 hours after dosing (Musick et al., 2010; Major et al., 2007). Although results 

of swine studies suggest that GI absorption of RDX was nearly complete, data cannot be used to 

determine a quantitative estimate of oral bioavailability because it is unlikely that fecal excretion of 

unabsorbed RDX was complete 24 hours after dosing (Snoeck et al., 2004). 

Oral bioavailability of RDX appears to vary depending upon the physical form of RDX and 

the matrix (e.g., soil, vegetation) in which it is administered. Schneider et al. (1977) compared the 

oral absorption of a single 100 mg/kg gavage dose of coarse granular [14C]-RDX as a slurry in 

isotonic saline with a single 50 mg/kg gavage dose of a finely powdered [14C]-RDX solution in saline 

in Sprague-Dawley rats. Plasma carbon-14 levels were measured for 24 hours after dosing. For 

both [14C]-RDX preparations, peak plasma levels of carbon-14 were observed 24 hours after oral 

administration, with a higher 24-hour plasma concentration for the 50 mg/kg dose (~4.7 μg/mL) 

compared to the 100 mg/kg dose (3.12 μg/mL). Results of this study indicate that the oral 

bioavailability of RDX may be greater for the finely powered preparation than for the coarse 

granular preparation consistent with a greater surface area available for absorption with finely 

powdered RDX. However, blood levels were only measured 24 hours after dosing, and the lower 

24-hour carbon-14 plasma concentration for the coarse granular preparation could be due to

slower absorption of coarse RDX granules compared with fine RDX powder, rather than lower 

overall bioavailability. 

Oral bioavailability of RDX is lower when administered as RDX-contaminated soil or when 

RDX is in plant materials that were grown on RDX-contaminated soils. Crouse et al. (2008)

investigated the oral bioavailability of RDX in contaminated soils relative to pure RDX by 

comparison of the AUC for the RDX blood concentration versus time curves. Adult male 

Sprague-Dawley rats were administered oral doses (in gelatin capsules) of pure RDX (99.9% purity; 

neat) or an equivalent amount of RDX in contaminated soils from the Louisiana Army Ammunition 

Plant (LAAP) or Fort Meade (FM). Blood concentrations for rats dosed with LAAP soil (1.24 mg/kg) 

and neat RDX (1.24 mg/kg) peaked at approximately 6 hours. The AUC and 6-hour RDX blood 

concentration were both approximately 25% lower for LAAP soil than for neat RDX (p ≤ 0.003 for 

AUC), suggesting that oral bioavailability of RDX from LAAP soil was 25% lower than neat RDX. For 

FM soil (0.2 mg/kg), RDX blood concentrations peaked at 6 hours compared to 4 hours for neat RDX 

(0.2 mg/kg). The 4-hour blood concentration for FM soil was approximately 15% lower than for 

neat RDX, although the AUC for FM soil was only 5% lower than for neat RDX (not statistically 

significant). Collectively, these results suggest that RDX in soil is absorbed following oral exposure 

and that it has a lower bioavailability than neat RDX. 
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 C-5 DRAFT―DO NOT CITE OR QUOTE

1 Fellows et al. (2006) showed that plants (alfalfa shoots and corn leaves) incorporated 

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[14C]-RDX grown on [14C]-RDX-amended soils. [14C]-RDX and plant metabolites of [14C]-RDX were

absorbed by voles following oral administration (Fellows et al., 2006). In adult male prairie voles 

(Microtus ochrogaster) fed diets containing RDX incorporated in plants for 5 or 7 days (average RDX 

dose per animal of 2.3 mg/kg-day), 94.8 and 96.6% (respectively) of the administered carbon-14

was eliminated in excreta (combined feces, urine, and CO2) and 3−5% was retained in the carcass. 

Feces, urine, and CO2 contained 74−79, 13−14, and 8−12% of the total carbon-14 in excreta, 

respectively. Based on carbon-14 elimination in urine and CO2 plus that retained by the carcass, the 

study authors estimated the oral bioavailability of plant-derived RDX to be >20%. However, if 

biliary excretion of RDX and/or RDX metabolites is a major excretory pathway in voles (as is the 

case with mice), estimates of bioavailability of plant-derived RDX could be substantially higher.

In Yorkshire piglets administered single doses of 5 or 10 mg/kg in gelatin capsules, peak 

plasma concentrations were proportional to the administered dose (Bannon, 2006). However, the 

potential for dose-dependence has not been evaluated over a wide range of doses.

RDX appears in blood within 1 hour following oral dosing; however, the rate of absorption 

may depend upon the physical form or dose of RDX (Bannon et al., 2009; Crouse et al., 2008; 

Bannon, 2006; Guo et al., 1985; MacPhail et al., 1985; Schneider et al., 1977). Oral absorption of 

RDX was rapid in LACA mice following stomach perfusion with [3H]-RDX (50mg/kg in methyl 

cellulose) (Guo et al., 1985). The tritium radiolabel was detected in blood 15 minutes following 

dosing and the highest concentrations in blood were observed 30 minutes after dosing. Based on 

an analysis of the blood tritium concentration kinetics, the authors estimated an absorption rate 

constant of 8.7 hour−1. In Sprague-Dawley rats administered single doses (0.2−18.0 mg/kg) of RDX 

in gelatin capsules, peak blood RDX concentrations were observed between 2.5 and 6 hours

(Bannon et al., 2009; Krishnan et al., 2009; Crouse et al., 2008). Peak blood concentrations 

occurred at 24 hours after Sprague-Dawley rats were administered a single oral dose (100 mg/kg) 

of coarse granular RDX in saline (Schneider et al., 1977). Similarly, peak RDX blood concentrations 

in swine administered single doses (5−10 mg/kg) of finally powdered (>98% pure) RDX in gelatin 

capsules occurred at 3−8 hours after dosing (Bannon et al., 2009), compared to 24 hours after a

single dose (100 mg/kg) of RDX administered as a finely powdered in saline (Bannon et al., 2009; 

Schneider et al., 1977). Peak plasma concentrations in Yucatan miniature swine administered a 

single dose of [14C]-RDX (45 mg/kg as a suspension in carboxymethylcellulose) were reached 

within 6−12 hours after dosing (Musick et al., 2010). Krishnan et al. (2009) and Sweeney et al. 

(2012a) estimated absorption rates in rats dosed with higher doses of coarse granular RDX to be 

approximately 100 times slower than absorption rates in rats dosed with lower doses of finely 

powdered neat RDX preparations or neat RDX dissolved in aqueous vehicles. For example,

Krishnan et al. (2009) estimated the absorption rate constant to be 0.75 hour−1 for rats dosed with 

neat RDX dissolved in water (1.53 or 2.07 mg/kg) or neat RDX in a gelatin capsule (0.2 or 
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1.24 mg/kg, Crouse et al. (2008)), compared to 0.0075 hour−1 1 for rats dosed with coarse granular 

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RDX (100 mg/kg, Schneider et al. (1977)). 

Inhalation Absorption

Studies evaluating absorption of RDX in humans following inhalation exposure were not 

identified. Several case reports have documented seizures and other neurological effects in 

individuals exposed to RDX either in a manufacturing setting or in the course of using RDX as a 

cooking fuel (Testud et al., 1996b; Testud et al., 1996a; Ketel and Hughes, 1972; Hollander and 

Colbach, 1969; Kaplan et al., 1965; Barsotti and Crotti, 1949). These reports suggest that RDX may 

be absorbed by the respiratory system. However, in several cases, the study authors were unable 

to clearly identify the primary route of exposure. In some cases, incidental oral exposure was 

suggested. Studies in laboratory animals have not investigated the absorption of RDX following 

inhalation exposure. 

Dermal Absorption

In vitro studies have demonstrated the dermal absorption of RDX in human and pig skin

(Reddy et al., 2008; Reifenrath et al., 2008). Reddy et al. (2008) reported that 5.7% of the applied 

RDX dose (in acetone) was absorbed into excised human skin in 24 hours. Dermal absorption of 

[14C]-RDX from both a low-carbon (1.9%) and a high-carbon (9.5%) soil was also assessed in this 

system. Approximately 2.6% of the RDX applied in the low-carbon soil and 1.4% applied in the 

high-carbon soil was absorbed after 24 hours. Thus, the dermal absorption of RDX from soils was 

reduced when compared with absorption from acetone, and absorption was lower in the 

high-carbon soil than in the low-carbon soil.

Reifenrath et al. (2008) investigated the influence of skin surface moisture conditions, soil 

carbon content, and soil aging on the in vitro percutaneous penetration of [14C]-labeled RDX in 

excised pig skin. Mean skin absorption of RDX was higher for low-carbon soil (1.2%), regardless of 

soil age and skin surface moisture. Absorption and evaporation were <1% for RDX regardless of 

soil type and age. While dermal absorption of certain munitions (e.g., 2,6-dinitrotoluene) is greatly 

enhanced by hydration of the skin surface, hydration had minimal effect on RDX mostly due to the 

lack of RDX volatility (e.g., <0.5% evaporation).

C.2.2. Distribution

Information on the distribution of absorbed RDX in humans is limited to a few cases of 

accidental exposures to RDX that provide data on the kinetics of RDX in blood and cerebrospinal 

fluid (Küçükardali et al., 2003; Ozhan et al., 2003; Woody et al., 1986). Concentrations of RDX in 

serum and cerebrospinal fluid were similar (11 and 9 mg/L, respectively) in a child 24 hours after 

ingesting an estimated dose of 85 mg/kg RDX (Woody et al., 1986). More extensive information on 

tissue distribution is available for animals, including mice, rats, and swine (Musick et al., 2010; 

Bannon, 2006; Reddy et al., 1989; Guo et al., 1985; MacPhail et al., 1985; Schneider et al., 1977). In 
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these studies, RDX or radiolabeled RDX ([14C] or [ 1 3H) was administered by the oral, intraperitoneal

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(i.p.), i.v., or intratracheal route and the distribution of the RDX or radiolabel was measured. Since 

metabolism of RDX can result in loss of carbon-14 or tritium from the parent compound, the 

distribution of radiolabel will not necessarily reflect the distribution of RDX (Schneider et al., 1977). 

To compare tissue distributions in studies in which animals received different doses by different 

routes of administration, distribution data are expressed as ratios of tissue RDX or radiolabel to 

that of either whole blood or plasma, whichever was reported. RDX in blood distributes into red 

blood cells and plasma to achieve concentration ratios that are close to unity. The plasma:whole 

blood carbon-14 ratio in swine that received a single oral dose of [14C]-RDX (45 mg/kg) was 

approximately 1.3 (Musick et al., 2010), and whole rat blood incubated in vitro with RDX had 

plasma:red blood cell RDX ratios of approximately 1.0 (Krishnan et al., 2009). As a result of the 

similarity between plasma and whole blood concentrations, tissue distribution is approximately 

equivalent when expressed as ratios of blood or plasma.

Studies conducted in rats, mice, and swine indicate that absorbed RDX distributes to many 

different tissues. Schneider et al. (1977) estimated the volume of distribution of RDX to be 

approximately 2.18 L/kg in rats, based on plasma RDX kinetics in rats that received a single i.p.

dose of RDX (5−6 mg/kg). Consistent with this estimate are observations of tissue:blood (or 

plasma) concentration ratios that exceed 1 in various tissues, including brain (showing that RDX 

can cross the blood:brain barrier), heart, kidney, and liver (Musick et al., 2010; Bannon et al., 2006; 

MacPhail et al., 1985; Schneider et al., 1977). Distribution within the brain may not be uniform. 

However, Bannon et al. (2006) observed tissue:blood concentrations for RDX of approximately 4 in 

brain hippocampus and 3.5 in brain cortex of swine that received a single oral dose of 10 mg/kg 

[14C]-RDX, although this is the only study that reported distribution for brain regions. Reported 

tissue:blood (or plasma) concentration ratios of RDX 24 hours following a single dose (oral or i.p.) 

were 1−9 for kidney, 1−7 for liver, and 1−3 for heart (Table C-2; Bannon (2006); (Schneider et al., 

1977). With repeated oral dosing (e.g., 30−90 days), tissue:blood ratios of RDX for these tissues are 

consistently greater than unity (Schneider et al., 1978). There is no consistent evidence that RDX 

accumulates in fat, although estimates of the fat:blood partition coefficient range from 6 to 8 and 

exceed that of other tissues (Sweeney et al., 2012a; Krishnan et al., 2009). 
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1 Table C-2. Distribution of RDX or radiolabel from administered RDXa

Animal Route

Dose

(mg/kg) Time (hrs) Brain Heart Kidney Liver Fat Source

Swine Oral 45b 24 0.6c 0.7 2.4 7.3 0.4 Musick et al. (2010)

Swine Oral 10d 3 3.5−4.0d 2 ≤1 <1 NAg Bannon et al. (2006)

Swine Oral 100d 24 1.5c 1.1 1.2−1.9 0.9 1.8 Schneider et al. (1977)

Rat Oral 100d 24 3.4c 2.9 6.6 0.7 NA Schneider et al. (1977)

Rat i.p. 50d 2 3.4c 2.6 8.8 5.7 NA Schneider et al. (1977)

Rat i.p. 500d ≤6.5 2.5c 2.1 4.8 3.3 NA Schneider et al. (1977)

Mouse Oral 50e 24 1c 0.8 1 1.4 0.8 Guo et al. (1985)

Mouse i.v. 2.5e 24 0.6f 0.8 0.7 1.6 0.4 Guo et al. (1985)

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a

Values are tissue:blood or tissue:plasma ratios following a single dose of either RDX, [14C]-RDX, or [3H]-RDX. b

Carbon-14. c

Tissue:plasma. d

RDX. e

Tritium. f

Tissue:blood. g

Not available. 

In rats, RDX can cross the placental:blood barrier resulting in exposure to the fetus, and can 

also be transported into maternal milk. Hess-Ruth et al. (2007) detected RDX in the brain tissue of 

postnatal day (PND) 1 rat pups (concentrations ranged from 0.64 to 7.6 μg/g brain tissue, with no 

differences between males and females) after maternal exposure to 6 mg/kg RDX via gavage from 

gestation day 6 to PND 10. RDX was also detected in maternal milk (concentrations ranged from 

3 to 5.7 μg/mL on PND 1 and from 0.7 to 3.1 μg/mL on PND 10).

C.2.3. Metabolism

The metabolism of RDX is not well characterized. No studies investigating the metabolism 

of RDX in humans were identified. Studies in animals indicate that RDX undergoes extensive 

metabolism, including denitration, ring cleavage, and generation of CO2. Predominant metabolic 

pathways and major organs involved in RDX metabolism have not been identified, although results 

of in vitro studies suggest a role for CYP450.

RDX undergoes metabolism through processes that generate CO2. In Sprague-Dawley rats 

administered a single 50 mg/kg gavage dose of [14C]-RDX, 43% was recovered as exhaled [14CO2] 

after four days (Schneider et al., 1977). Similarly, approximately 30−50% of the radioactivity was 

recovered as exhaled [14CO2] in rats administered [14C]-RDX in saturated drinking water or daily 

gavage for up to three months (Schneider et al., 1978). Metabolism of RDX to CO2 was also 

observed in prairie voles following dietary exposure (average RDX dose per animal of 

2.3 mg/kg-day) to [14C]-RDX incorporated plant materials for 5−7 days, with approximately 9% of 

the administered [14C]-RDX dose eliminated as exhaled [14CO2] (Fellows et al., 2006). 
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1 Terminal metabolites of RDX have been identified in the urine of rats and swine, with very 

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little urinary excretion of parent compound, indicating extensive metabolism of RDX. Following 

oral administration of a single 50 mg/kg gavage dose of [14C]-RDX, 3.6% of the urinary radioactivity 

was identified as unmetabolized RDX (Schneider et al., 1977). Total urinary radiolabel accounted 

for about one third of the administered label and unmetabolized RDX contributed 3−5% of total 

urinary radioactivity in rats exposed to [14C]-RDX-saturated drinking water for 1 or 13 weeks

(Schneider et al., 1978). Similar results were observed in Yucatan swine administered a single 

45 mg/kg oral dose of [14C]-RDX, with approximately 1−3.5% of the urinary radioactivity as parent 

RDX (Major et al., 2007). Urinary metabolites were not characterized in these studies (Schneider et 

al., 1978, 1977). However, Schneider et al. (1978) cited unpublished findings in their laboratory 

that, in addition to carbon dioxide, other one-carbon intermediates were produced including 

bicarbonate and formic acid. 

In the environment, the predominant breakdown products of RDX are methylenedinitramie 

and 4-nitro-2-diazbutanal (Sweeney et al., 2012b; Paquet et al., 2011). RDX metabolism in animals 

is less well understood. N-nitroso RDX metabolites have been identified as derived through 

anaerobic metabolism (ATSDR, 2012; Pan et al., 2007b). Based on characterization of RDX 

metabolites in urine and plasma of miniature swine, metabolism of RDX appears to involve loss of 

nitro groups and ring cleavage (Musick et al., 2010; Major et al., 2007). The two principal urinary 

metabolites identified in miniature swine following a single oral dose of 43 or 45 mg/kg were 

4-nitro-2,4-diazabutanal and 4-nitro-2,4-diaza-butanamide (see Table C-3). Bhushan et al. (2003)

suggested that the formation of the 4-nitro-2,4-diazabutanal metabolite occurred via denitration 

followed by hydroxylation and spontaneous hydrolytic decomposition resulting in ring cleavage 

and aldehyde formation. In the miniature swine gavage studies, only trace amounts of the 

nitrosamine RDX metabolites hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) and 1-nitro3,5-dinitroso-1,3,5-triazacyclohexane (DNX) were found in urine (Musick et al., 2010; Major et al., 

2007). In plasma, most of the radioactivity existed as RDX, with trace levels of MNX, DNX, and 

1,3,5-trinitroso-1,3,5-triazacyclohexane (TNX). The study authors suggested that the trace levels of 

MNX, DNX, and TNX in plasma may have been formed within the GI tract via sequential nitrogen 

reduction by intestinal bacteria (Major et al., 2007). The low levels of these compounds in urine 

and plasma were attributed to the nearly complete absorption of RDX from the GI tract, leaving 

little parent compound available for bacterial metabolism within the GI tract. In a study of female 

deer mice (Peromyscus maniculatus) fed diets containing RDX at concentrations of 12 and 120 

mg/kg for 9 days, MNX and DNX were identified in the stomach but TNX was not detected (Pan et 

al., 2007b). MNX and DNX were also measured in various organs of female B6C3F1 mice provided 

RDX in feed at doses of 0.38−522 mg/kg; TNX was also detected in some organ compartments, but 

not in the liver. The authors concluded that RDX can be metabolized into its N-nitroso compounds 

in mice, but did not identify a mechanism for the formation of the metabolites. Comparing RDX 

with MNX and TNX, RDX was the most potent compound at causing overt signs of toxicity (seizures 
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1 and mortality) as determined through identification of the median lethal dose using the EPA up2

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and-down procedure in deer mice of varying ages (Smith et al., 2009; Rispin et al., 2002). 

Table C-3. Principal urinary metabolites of RDX in miniature swine 24 hours 

after dosing with RDX

Sample origin Metabolite name Metabolite structure

Urine peak 1 M1 4-Nitro-2,4-diazabutanal

Urine peak 2 M2 4-Nitro-2,4-diaza-butanamide

Sources: Major et al. (2007); Musick et al. (2010).

Although the metabolic pathways and major tissues involved in RDX metabolism have not 

been identified, there is some evidence for the involvement of the liver and CYP450 enzymes. 

Comparison of hepatic radioactivity to liver concentrations of RDX after a single gavage dose to rats 

suggested the presence of RDX metabolites and a possible role for hepatic metabolism of RDX

(Schneider et al., 1977). In vitro data indicated that CYP450 may be involved in the metabolism of 

RDX (Bhushan et al., 2003). Incubation of RDX with NADPH and rabbit liver CYP450 2B4 under 

anaerobic conditions produced nitrite, 4-nitro-2,4-diazabutanal, formaldehyde, and ammonium ion

(Bhushan et al., 2003). The reaction rate under aerobic conditions was approximately one-third of 

that observed under anaerobic conditions. Several CYP450 inhibitors (ellipticine, metyrapone, 

phenylhydrazine, 1-aminobenzotriazole, and carbon monoxide) decreased the formation of RDX 

metabolites (55−82% inhibition), providing support for the role of CYP450 in RDX metabolism.

C.2.4. Excretion

The primary routes of elimination of absorbed RDX are excretion of RDX and metabolites in 

urine, and exhalation of CO2 liberated from metabolism of RDX (Sweeney et al., 2012a; Musick et al., 

2010; Krishnan et al., 2009; Major et al., 2007; Schneider et al., 1977). Tritium derived from 

administered [3H]-RDX has been detected in mouse gall bladder contents, suggesting biliary 

secretion in this species (Guo et al., 1985); however, biliary secretion of RDX or metabolites has not 

been confirmed in other animal species. Studies conducted in the rat and swine suggest that 

metabolism is the dominant mechanism of elimination of absorbed RDX. In both species, 

metabolites dominated the carbon-14 distribution in urine of animals that received doses of 

[14C]-RDX, with RDX accounting for <5% of the urinary carbon-14 (Musick et al., 2010; Schneider et 

al., 1977). 

Data on kinetics of elimination of absorbed RDX from blood are available from reports of 

accidental exposures of humans to RDX (Table C-4). Woody et al. (1986) estimated the elimination 
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1 t1/2 to be approximately 15 hours in a child who ingested approximately 85 mg of RDX per kg of 

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body weight. The t1/2 estimate was based on measured serum concentrations of RDX made 

between 24 and 120 hours following ingestion for RDX. Based on plasma RDX concentration data 

from five adults exposed to RDX (measurements made between 24 and 96 hours following 

exposure) (Ozhan et al., 2003), a first-order elimination t1/2 of 20−30 hours was derived (calculated 

for this review by fitting the serum RDX data to a first-order exponential function). It needs to be 

noted that it is not possible to draw reliable inferences from these values since they are based on 

accidental, acute exposures and, in particular, the data for the child is based on a single set of 

measurements for one individual.

Table C-4. Elimination t1/2 values for RDX or radiolabeled RDX

Animal Route Dose (mg/kg) Timea t1/2 (hrs) Source

Human (child) Oral 85b 24−120 hrs 15.0c Woody et al. (1986)

Human (adult) Oral NA 24−96 hrs 21−29c,d Ozhan et al. (2003)

Rat i.v. 5−6 0.5 min−6 hrs 10b Schneider et al. (1977)

Rat i.v. 0.8−1.0 30 min−10 hrs 4.6c,d Krishnan et al. (2009)

Rat Oral 1.53−2.07 1−10 hrs 6.9c,d Krishnan et al. (2009)

Mouse i.v. 2.5 1.5 min−24 hrs 26d,e Guo et al. (1985)

Mouse Oral 50 1.5 min−168 hrs 53d.e Guo et al. (1985)

a

Observation period following exposure on which the t1/2 values were based. b

Reported estimate of dose based on blood kinetics. c

Value for blood RDX. d

Calculated for this review based on reported plasma RDX or tritium data. e

Value for blood tritium.

The kinetics of elimination of absorbed RDX from blood has been evaluated in rats and 

mice; in both species, elimination kinetics were bi-phasic (Krishnan et al., 2009; Guo et al., 1985; 

Schneider et al., 1977). As shown in Table C-4, estimated t1/2 values for the terminal elimination 

phase in rats range from 5 to 10 hours (Krishnan et al., 2009; Schneider et al., 1977). Guo et al. 

(1985) estimated the terminal elimination t1/2 for RDX-derived tritium in mice to be approximately 

26 hours following a single i.v. dose of [3H]-RDX (2.5 mg/kg). The elimination t1/2 for tritium in 

mice following an oral dose of [3H]-RDX (50 mg/kg) was approximately 53 hours (Guo et al., 1985). 

The shorter elimination t1/2 estimated for rats (Krishnan et al., 2009; Schneider et al., 1977) 

compared to mice (Guo et al., 1985) may reflect a real species difference in elimination kinetics of 

RDX, or may reflect a difference between the kinetics of elimination of RDX and of tritium derived 

from [3H]-RDX, which would include RDX metabolites.
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1 C.2.5. Physiologically-Based Pharmacokinetic (PBPK) Models

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Overview of Available PBPK Models

A PBPK model to simulate the pharmacokinetics of RDX in rats was first developed by

Krishnan et al. (2009) and improved upon to extend the model to humans and mice (Sweeney et al., 

2012a; Sweeney et al., 2012b). The Sweeney et al. (2012a) model consists of six main 

compartments: blood, brain, fat, liver, and lumped compartments for rapidly perfused tissues and 

slowly perfused tissues (Figure C-1). The model can simulate RDX exposures via the IV or oral 

route. Distribution of RDX to tissues is assumed to be flow-limited. Oral absorption is represented 

in this model as first-order uptake from the gastrointestinal tract into the liver, with 100% of the 

dose absorbed. RDX is assumed to be cleared by first-order metabolism in the liver. However, 

there is no representation of the kinetics of any RDX metabolites. The acslX model code (Advanced 

Continuous Simulation Language, Aegis, Inc., Huntsville, Alabama) was obtained from the authors of

Sweeney et al. (2012a). 

Figure C-1. PBPK model structure for RDX in rats and humans. Exposure to 

RDX is by the IV or oral route and clearance occurs by metabolism in the liver. See 

Table C-5 for definitions of parameter abbreviations. The GI tract is represented as 

1-compartment in Krishnan et al. (2009) (on the left) and 2-compartments in

Sweeney et al. (2012a) (on the right).
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1 The parameter values used in the Sweeney et al. (2012a) rat model are listed in Table C-5. 

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The physiological model parameter values for cardiac output, tissue volumes, and blood perfusion 

of tissues were obtained from the literature (Timchalk et al., 2002; Brown et al., 1997). RDX 

tissue:blood partition coefficients for liver (PL), brain (PB), and richly perfused tissues (PR) were 

estimated with an algorithm that relates the measured n-octanol: water partition coefficient for 

RDX to reported compositions of water and lipids in specific rat tissues (Poulin and Theil, 2000; 

Poulin and Krishnan, 1995). Tissue:blood partition coefficients for fat (PF) and slowly perfused 

tissues (PS), as well as the metabolic rate constant (KfC) were simultaneously optimized to fit rat 

blood RDX concentrations following IV doses of 0.77 or 1.04 mg/kg RDX (Krishnan et al., 2009) 

producing values of 5.57, 0.15, and 2.6 kg0.33/hour for PF, PS, and KfC, respectively. While, the 

optimized value for PS is much smaller than that used by Krishnan et al. (2009) of 1.0, the 

optimized values for PF and KfC were fairly similar to those used by Krishnan et al. (2009) of 7.55, 

and 2.2 kg0.33/hour. The rat model with these parameter values also had good agreement with 

blood RDX concentrations after a 5−6 mg/kg IV exposure (Schneider et al., 1977). 

The GI tract oral absorption rate constant (KAS) was optimized to fit the time-course 

concentration data for rat oral dosing studies. The Krishnan et al. (2009) model used a 

1-compartment GI tract. KAS was fit to the RDX blood concentrations in Krishnan et al. (2009) and 

the model with this parameter value had good agreement with the blood RDX concentrations after 

0.2 and 1.24 mg/kg oral exposures (Crouse et al., 2008). The value of KAS was adjusted to fit the 

RDX blood concentrations in the Schneider et al. (1977) study. Sweeney et al. (2012a) modified the 

GI tract description by adding a second GI compartment and corresponding oral absorption 

parameters (KAS, KAD, and KT) to fit the blood concentrations from Krishnan et al. (2009). For the 

other oral dosing studies the 2-compartment GI model did not improve the model fit to the data, so 

KT was set equal to zero making the GI submodel equivalent to a 1-compartment model. The value 

of KAS was adjusted separately to fit the oral studies with RDX in capsules (Bannon et al., 2009; 

Crouse et al., 2008) and coarse grain RDX in a saline slurry (Schneider et al., 1977). 

The Sweeney et al. (2012a) model fits to blood and brain RDX concentrations for rats were 

mostly within a factor of 1.5 of the experimentally measured values indicating a tightly calibrated 

model. 

Human RDX toxicokinetics were modeled with the same model structure as for rats. Values 

for the human physiological parameters such as tissue volumes and blood perfusion of tissues were 

obtained from the literature (Brown et al., 1997). Human absorption and metabolic clearance rate 

constants were optimized to fit observed RDX blood concentrations from a case study of ingestion 

by a 3-year-old boy (Woody et al., 1986), and a study where five soldiers were intentionally or 

accidentally exposed to RDX powder via inhalation or dermal contact (Ozhan et al., 2003). The 

amounts of RDX ingested in both studies were unknown, so Sweeney et al. (2012a) estimated the 

dose amount by optimizing this parameter to fit the data (Table C-5). Sweeney et al. (2012a)

initially simulated each individual soldier’s blood level data separately. The resulting parameter 
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1 values were similar, so data from the five soldiers were combined and the rate constants re2 

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estimated using the combined data. For comparison, the rat metabolic rate constant (KfC) was 

scaled to humans; the rat KfC (from fitting to in vivo data) was multiplied by the ratio of the human 

to rat metabolic rate constants measured in vitro and by the ratio of human to rat microsomal 

protein levels (Cao, 2008; Lipscomb and Poet, 2008). The scaling from rats yielded a human in vivo

metabolic rate constant of 12.4 kg-bw0.33/hour which is similar to the values Sweeney et al. (2012a)

derived by fitting the combined Ozhan et al. (2003) adult data (11.2 kg-bw0.33/hour) and the Woody 

et al. (1986) child data (9.87 kg-bw0.33/hour).

Mouse RDX toxicokinetics were also modeled by Sweeney et al. (2012b) using the same 

model structure as for rats. Values for the mouse physiological parameters such as tissue volumes 

and blood perfusion of tissues were assumed to be the same as the body weight normalized 

parameter values in the rat model. RDX tissue:blood partition coefficients for liver (PL), brain (PB), 

and richly perfused tissues (PR) were estimated with an algorithm that relates the measured 

n-octanol: water partition coefficient for RDX to reported compositions of water and lipids in 

specific mouse tissues (Poulin and Theil, 2000; Poulin and Krishnan, 1995). The rate constant for 

metabolism (KfC), and the oral absorption rate constant (KAS), were optimized to fit measured 

mouse RDX blood concentrations (Sweeney et al., 2012b). The KfC value estimated for the mouse 

(102 kg0.33/hour) is much higher than those estimated for rats and humans (2.6 and 

11.2 kg0.33/hour, respectively); however, the KAS value (0.51/hour) fit to mouse data is similar to 

the value (0.83/hour) used in the RDX rat model for gavage in water. The Sweeney et al. (2012b)

model predictions of blood RDX concentrations were in good agreement with the experimental 

mouse gavage data reported in the same study. 

Table C-5. Parameter values used in the Sweeney et al. (2012a) and Sweeney

et al. (2012b) PBPK models for RDX in rats, humans, and mice

Parameter (abbreviation; units) Rat Human Mouse Source

Body weight (BW; kg) 0.3 70 0.0206 Default values; study-specific values 

used if available

Cardiac output (KQC, L/h/kg0.74) 15 14 15 Timchalk et al. (2002); Brown et al. 

(1997)

Tissue volumes (fraction of BW)

Liver (KVL) 0.04 0.026 0.04 Timchalk et al. (2002); Brown et al. 

(1997)

Brain (KVB) 0.012 0.02 0.012 Timchalk et al. (2002); Brown et al. 

(1997)

Fat (KVF) 0.07 0.21 0.07 Timchalk et al. (2002); Brown et al. 

(1997)

Richly perfused tissues (KVR) 0.04 0.052 0.04 Timchalk et al. (2002); Brown et al. 

(1997)
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Parameter (abbreviation; units) Rat Human Mouse Source

Blood (KVV) 0.06 0.079 0.06 Timchalk et al. (2002); Brown et al. 

(1997)

Slowly perfused tissues (KVS) 0.688 0.523 0.688 0.91-(KVL+KVB+KVF+KVR+KVV)

Blood flows (fraction of cardiac output)

Liver (KQL) 0.25 0.175 0.25 Timchalk et al. (2002); Brown et al. 

(1997)

Brain (KQB) 0.03 0.114 0.03 Timchalk et al. (2002); Brown et al. 

(1997)

Fat (KQF) 0.09 0.085 0.09 Timchalk et al. (2002); Brown et al. 

(1997)

Slowly perfused tissues (KQS) 0.2 0.2449 0.2 Timchalk et al. (2002); Brown et al. 

(1997)

Richly perfused tissues (KQR) 0.43 0.3811 0.43 1-(KQL+KQB+KQF+KQS)

Tissue:blood partition coefficients 

Liver (PL) 1.2 1.3 1.3 Krishnan et al. (2009)a

Brain (PB) 1.4 1.6 1.6 Krishnan et al. (2009)a

Richly perfused tissues (PR) 1.4 1.6 1.6 Krishnan et al. (2009)a

Fat:blood PC (PF) 5.57 5.57 5.57 Sweeney et al. (2012a)b

Slowly perfused tissues (PS) 0.15 0.15 0.15 Sweeney et al. (2012a)b

Metabolism

First-order metabolic rate constant 

(KfC; kg0.33/hr)

2.6 9.87 (child); 

11.2 (adults)

102 Sweeney et al. (2012a)b,c;

Sweeney et al. (2012b)d

GI absorption

Dosing via gavage

Absorption from compartment 1 

(KAS, /hr)

0.83 0.033 0.51 Sweeney et al. (2012a)c,d,e

Transfer from compartment 1 to 

compartment 2 (KT, /hr)

1.37 0 0 Sweeney et al. (2012a)c,d

Absorption from compartment 2 

(KAD, /hr)

0.0258 0 0 Sweeney et al. (2012a)c,d

Dosing via capsule (KAS, /hr) 0.12 NA NA Sweeney et al. (2012a)e

“coarse” RDX formulation (KAS, /hr) 0.005 NA NA Sweeney et al. (2012a)e

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Predicted from n-octanol:water PC. b

Optimized from rat IV data. c

Optimized from human data of Ozhan et al. (2003) and Woody et al. (1986). d

Optimized from mouse oral data. e

Optimized from rat oral data of Bannon et al. (2009), Crouse et al. (2008), Krishnan et al. (2009), and Schneider et 

al. (1977). 
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Note: Parameter values used in the Sweeney et al. (2012a) and Sweeney et al. (2012b) PBPK models for RDX in 

rats, humans, and mice.

The above PBPK model was evaluated and subsequently modified by EPA for use in doseresponse modeling in this assessment. This is detailed in the following section.

PBPK Model Evaluation and Further Development of the Sweeney et al. (2012a) and Sweeney et 

al. (2012b) Models 

EPA evaluated and performed a quality control check of the PBPK models for RDX in rats, 

humans, and mice published by Sweeney and colleagues (Sweeney et al., 2012a; Sweeney et al., 

2012b). The conclusions from these analyses are summarized below and then discussed in more 

detail: 

1) The model code and the parameter values matched the published reports. 

2) The absorption of RDX from the GI tract did not use a consistent structure; for gavage doses 

the model used a 2-compartment GI submodel and for other oral exposures (e.g., gelatin 

capsule) the model used a 1-compartment GI submodel. The model was revised to have a 

1-compartment GI submodel to simulate all oral exposures with a consistent set of 

absorption parameters for each dosage formulation of administered RDX. 

3) Additional oral rat data were identified from single dose studies (MacPhail et al., 1985; 

Schneider et al., 1977) and subchronic studies (Schneider et al., 1978) and were used for 

model calibration as well as independent comparison against model predictions. 

4) In addition to the sensitivity analysis conducted by Sweeney et al. (2012b) on the mouse 

model, a sensitivity analysis in the rat and human models was performed.

5) The Sweeney et al. (2012b) mouse model used the same physiological parameters scaled to

body weight as the rat model. This mouse model was revised to use mouse specific 

physiological parameters.

The Sweeney et al. (2012a) model for rats was modified by changing the oral absorption 

rate constants (as discussed below) and the partition coefficients for the fat and slowly perfused 

tissues (PF and PS) as shown in Table C-6. The partition coefficients for the fat and slowly perfused 

tissues were set to the values calculated by Krishnan et al. (2009) relating the measured n-octanol: 

water partition coefficient for RDX to reported compositions of water and lipids in those tissues. 

The fits to RDX blood time course data after iv exposure (Figure C-2) are slightly worse than the

Sweeney et al. (2012a) rat model because the Sweeney et al. (2012a) rat model optimized the 

fat:blood and slowly perfused tissue partition coefficients to fit the data. 
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Figure C-2. EPA rat PBPK model predictions fitted to observed RDX blood 

concentrations in male and female SD rats following intravenous exposure. A) 

data from Krishnan et al. (2009) (0.4 kg rats) and B) data from Schneider et al. 

(1977) (simulation of 0.25 kg rats and 5.5 mg/kg dose for 0.2−0.25 kg rats and 

5−6 mg/kg dose).

Table C-6. Parameters values used in the EPA application of the rat, human, 

and mouse models 

Parameter (abbreviation; units) Rat Human Mouse Source

Body weight (BW; kg) 0.3 70 0.0206 Default values shown; study-specific 

values used if available

Cardiac output (KQC; L/h/kg0.74) 15 14 15 Timchalk et al. (2002); Brown et al. 

(1997)

Tissue volumes (fraction of BW)

Liver (KVL) 0.04 0.026 0.055 Timchalk et al. (2002); Brown et al. 

(1997)

Brain (KVB) 0.012 0.02 0.017 Timchalk et al. (2002); Brown et al. 

(1997)

Fat (KVF) 0.07 0.21 0.07 Timchalk et al. (2002); Brown et al. 

(1997)

Richly perfused tissues (KVR) 0.04 0.052 0.071 Timchalk et al. (2002); Brown et al. 

(1997)

Blood (KVV) 0.06 0.079 0.049 Timchalk et al. (2002); Brown et al. 

(1997)

Slowly perfused tissues (KVS) 0.688 0.523 0.648 0.91-(KVL+KVB+KVF+KVR+KVV)

Blood flows (fraction of cardiac output)
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Parameter (abbreviation; units) Rat Human Mouse Source

Liver (KQL) 0.25 0.175 0.25 Timchalk et al. (2002); Brown et al. 

(1997)

Brain (KQB) 0.03 0.114 0.03 Timchalk et al. (2002); Brown et al. 

(1997)

Fat (KQF) 0.09 0.085 0.09 Timchalk et al. (2002); Brown et al. 

(1997)

Slowly perfused tissues (KQS) 0.2 0.2449 0.2 Timchalk et al. (2002); Brown et al. 

(1997)

Richly perfused tissues (KQR) 0.43 0.3811 0.43 1-(KQL+KQB+KQF+KQS)

Tissue:blood partition coefficients and metabolism

Liver (PL) 1.2 1.3 1.3 Krishnan et al. (2009)a

Brain (PB) 1.4 1.6 1.6 Krishnan et al. (2009)a

Richly perfused tissues (PR) 1.4 1.6 1.6 Krishnan et al. (2009)a

Fat:blood PC (PF) 7.55 7.55 7.55 Krishnan et al. (2009)a

Slowly perfused tissues (PS) 1.0 1.0 0.9 Krishnan et al. (2009)a

First-order metabolic rate constant 

(KfC; kg0.33/hr)

2.6 9.87(small 

boy); 

11.2(soldiers)

77 Sweeney et al. (2012a)b,c; Sweeney et 

al. (2012b)d

Absorption

Absorption from GI to liver (KAS; /hr) Table 

C-7

1.75 0.6 Fit to rat, human, and mouse oral data

Absorption from lung to blood 

(Klung; /hr)

0.75 Fit to human data

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Predicted from n-octanol:water PC. b

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Optimized from human data of Ozhan et al. (2003) and Woody et al. (1986). d

Optimized from mouse oral data, and differs from that obtained by Sweeney et al. (2012b). 

Absorption of RDX from the GI Tract

As discussed above in the oral absorption section under toxicokinetics (Section C.2.1) the 

rate of oral absorption depends on the physical form of RDX. This was demonstrated by comparing 

the Schneider et al. (1977) studies which used gavage doses of 100 mg/kg of coarse granular RDX 

and 50 mg/kg finely powdered RDX and observing the 50 mg/kg finely powdered RDX had a higher 

peak plasma level. These results are likely explained by the smaller surface area to mass ratio of 

the coarse grain RDX leading to slower dissolution and absorption.

To follow the rule of model parsimony (i.e., use no more parameters than needed for the 

best fit to all of the data), oral absorption was modeled with a 1-compartment GI tract sub-model 

for all simulations. To account for the differences in absorption due to the physical form of RDX, 
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1 separate rate constants for RDX oral absorption were optimized to fit measured blood 

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concentrations of RDX according to the type of dosing formulation and the model fits obtained with 

the EPA’s revised parameters for rats are shown in Figure C-3 to C-5. The oral dosing formulations 

were grouped into four categories; RDX dissolved in water, RDX in capsules, fine grain and coarse 

grain RDX. The absorption rate constant for RDX dissolved in water was optimized to the data in 

the Krishnan et al. (2009) study (Figure C-3). The absorption rate constant for RDX in capsules was 

optimized to the data in the Crouse et al. (2008) and Bannon et al. (2009) studies (Figure C-4). The 

absorption rate constant for fine grain RDX was optimized to the data described below (Additional 

RDX time-course data) in the MacPhail et al. (1985) and Schneider et al. (1977) studies (Figure C-7). 

The Schneider et al. (1977) study was used to estimate the absorption rate constants for coarse 

grain RDX (Figure C-5; as represented by the fit to the data obtained by the solid curve at 100% 

bioavailability). Overall, the fits of the EPA revised model to the blood time-course data of these 

studies are similar to the fits of theSweeney et al. (2012a) rat model. The fits to RDX brain time 

course data after oral exposure to RDX in capsules (Figure C-6A) are similar to the fits of the

Sweeney et al. (2012a) rat model. The absorption rate constants for each dosing formulation are 

listed in Table C-7. 

An alternative to varying the absorption rate constant (KAS) for each RDX formulation 

would be to vary the oral bioavailability, in effect modifying the administered exposure 

concentration. Therefore, the sensitivity of the model fit to variations in oral bioavailability was 

examined in Figure C-5 and an analysis of model sensitivity to oral bioavailability was conducted as 

discussed further in the section, Sensitivity analysis of the rat PBPK model. 

Table C-7. Doses, dosing formulations, and absorption rate constants in 

animal and human studies

Formulation Study Dose Estimated KA (/hr)

RDX dissolved in water Krishnan et al. (2009) 1.53, 2.07 mg/kg 

single gavage

1.75

Schneider et al. (1978) ~5−8 mg/kg-d drinking 

water 90 d

Dry RDX in capsulesa Crouse et al. (2008) 0.2, 1.24 mg/kg single dose 0.35

Bannon et al. (2009) 3, 18 mg/kg 

single dose

Fine grain RDX in saline 

slurry

Schneider et al. (1977) 50 mg/kg 

single gavage

0.19

MacPhail et al. (1985)b 50 mg/kg 

single gavage

Coarse grain RDX in saline 

slurry

Schneider et al. (1977) 100 mg/kg 

single gavage

0.00497

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a 1 Capsules were filled with dry RDX from stock solution of acetone and acetone was evaporated off.

2 b

RDX particle size was ≤ 66 μm in diameter suspended in a 2% solution of carboxymethylcellulose.

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Figure C-3. EPA rat PBPK model predictions fitted to observed RDX blood 

concentrations following oral exposure to RDX dissolved in water. Male and 

female SD rats (0.4 kg) were dosed by gavage (Krishnan et al., 2009). 

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Figure C-4. EPA rat model predictions fitted to observed RDX blood 

concentrations following oral exposure to RDX in dry capsules. The ingested 

RDX doses were A) 0.2 and 1.24 mg/kg RDX in male SD rats (0.4 kg, data from

Crouse et al. (2008)) and B) 3 and 18 mg/kg RDX in male and female SD rats 

(0.35 kg, data from Bannon et al. (2009)) for KAS = 0.35/hour. 
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Figure C-5. Effect of varying oral absorption parameters on EPA rat model 

predictions fitted to observed RDX blood concentrations following oral 

exposure to coarse grain RDX. Symbols denote observed RDX blood 

concentrations measured in male SD rats (0.225 kg) resulting from oral doses 

of 100 mg/kg RDX (Schneider et al., 1977). The absorption rate constant (KAS) 

fit to these data assuming 100% bioavailability resulted in the same estimate 

(KAS = 0.00497/hour) as obtained by Sweeney et al. (2012a). Alternatively, for KAS 

fixed at the value fit to fine grain RDX in a saline slurry (KAS = 0.019/hour fit to data 

from Schneider et al. (1977) and MacPhail et al. (1985), Figure C-7) the estimate of 

oral bioavailability fit to the RDX blood concentrations was 35%. A bioavailability of 

40% and KAS = 0.019/hour is also shown for comparison. 

Figure C-6. EPA rat model predictions fitted to observed RDX brain tissue 

concentrations following oral exposure to RDX. A) 3 and 18 mg/kg RDX in dry 

capsules (0.35 kg male and female rats data from Bannon et al. (2009)); best fit 

KAS = 0.35/hour. B) 50 mg/kg fine grain RDX in a saline slurry (0.25 kg male and 

female rats data from MacPhail et al. (1985)); best fit KAS = 0.019/hour. 
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1 Additional RDX Time-Course Data

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The EPA revised models were simultaneously fitted against additional RDX time course data 

(not used in the original Sweeney et al. (2012a) model calibration) from two studies in which 

animals received oral doses of fine grain RDX (MacPhail et al., 1985; Schneider et al., 1977) in 

Figure C-7 and RDX brain time course data from a study in which animals received oral doses of

fine grain RDX (Figure C-6B). Overall the calibrated EPA rat model predictions are within a factor 

of 1.5 of the measured values from different data sets, and therefore likely provides a more robust 

estimated parameter. 

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Figure C-7. EPA rat model predictions fitted to observed RDX blood 

concentrations following oral exposure to fine grain RDX in a saline slurry. 

Oral doses of 50 mg/kg RDX were administered to A) male SD rats (0.225 kg)

(Schneider et al., 1977) and B) male and female SD rats (0.25 kg) data (MacPhail et 

al., 1985). Best fit KAS = 0.019/hour. 

Following calibration, the EPA model was further tested by comparison with results from 

two other subchronic oral studies in male and female rats (Schneider et al., 1978). These were a 

gavage study where 20 mg/kg RDX was administered in saline slurry and a drinking water study 

where rats were provided with RDX-saturated drinking water (50−70 μg/mL) ad libitum for which 

the study authors estimated a daily dose between 5 and 8 mg RDX/kg BW. It is striking that the 

observed RDX blood concentrations in the gavage study (Figure C-8, symbols) were virtually the 

same as or only slightly elevated compared to the blood concentrations reported in the drinking 

water exposures, with an approximately threefold lower daily administered dose in the drinking 

water study (Figure C-9, symbols). This is counter to the expectation that higher doses cause 

higher blood levels and is discussed further below. 

EPA’s modified PBPK model was set up to simulate drinking water exposures with a noncontinuous sipping pattern based on Spiteri (1982) which assumed 80% of the consumption to 
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occur episodically at night when the rats were awake3 1 . The model predicts blood concentrations to 

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increase in proportion to the total dose; for the gavage study the model predictions yielded an RDX 

blood concentration approximately threefold higher than the reported mean blood concentrations 

(Figure C-8) while for the subchronic drinking water study the model fit the data reasonably well 

(Figure C-9). 

It is possible that multiple mechanisms such as elimination of unabsorbed RDX or metabolic 

induction may explain why the observed RDX blood concentrations did not increase in proportion 

to the higher administered dose in the gavage studies compared to the drinking water. Elimination 

of unmetabolized RDX may be an insignificant factor in the single-dose studies used for calibration 

of the absorption constant for the RDX in saline slurry, but for repeated, higher doses this 

elimination route could be significant. Schneider et al. (1978) found similar RDX concentrations in 

the feces of rats in the gavage and drinking water studies (3.1 ± 2.0 and 2.7 ± 1.3 micrograms RDX 

per gram dry weight feces, respectively). The total recovery of radioactivity in feces was also 

similar in the gavage study (4.8 ± 0.8%, week 1 only) and drinking water study (4.4 ± 0.6%, 

measured over the course of the study). Thus, the difference in fecal elimination for the two routes 

does not appear significant. 

It is also possible that metabolic induction occurred during the repeated dosing of RDX in 

the gavage study leading to the lower RDX blood concentrations seen. The reasonably good fits to 

the model to the drinking water data set demonstrated achievement of regular periodic levels,

indicate a lack or much lower extent of metabolic induction over time from those repeated doses, 

possibly because the dose rate was lower: 5−8 mg/kg-day vs. 20 mg/kg-day in the gavage study. 

Overall the reasonable agreement of the modified EPA RDX rat model with the subchronic drinking 

water data support use of the model in estimating and extrapolating blood levels following chronic 

exposure at or below this exposure range (5−8 mg/kg-day), particularly in drinking water. 

 

3A constant drinking water ingestion rate interspaced between episodes of no ingestion was assumed. Each 

12-hour awake period consisted of 8 cycles that alternated between 1.5-hour cycles of frequent sipping 

(continuous ingestion) and zero ingestion for 45 minutes each. Each 12-hour sleeping period consisted of 

4 cycles with regular sipping periods of 30 minutes followed by 2.5 hours of no ingestion.
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Figure C-8. Comparison of EPA rat model predictions with data from Schneider 

et al. (1978) for the subchronic gavage study. Model fits and mean observed RDX 

blood concentrations resulting from daily gavage doses of 20 mg/kg RDX for 

90 days to male and female SD rats (0.225 kg). The RDX in saline slurry was 

assumed to be coarse grained with oral absorption rate constant 

KAS = 0.00497/hour.

Figure C-9. Comparison of EPA rat model predictions with data from Schneider 

et al. (1978) for the subchronic drinking water study. Model fits and mean 

observed RDX blood concentrations resulting from a daily estimated dose of 6.5 mg 

RDX/kg-day for 90 days to male and female SD rats (0.225 kg). The large peak to 

trough change in the simulation results from model representation of the daily oral 

ingestion of drinking water primarily during the waking state. The oral absorption 

rate constant for RDX dissolved in water was used (KAS = 1.75/hour).
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1 Simulating Exposures in Humans

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The Sweeney et al. (2012a) model for humans was modified in the same ways as the rats, by 

changing the partition coefficients for the fat and slowly perfused tissues (PF and PS) as shown in 

Table C-6 and fitting the rate constants for oral absorption and metabolism to RDX blood 

concentration data. In the studies of humans with measured RDX blood concentrations by Woody 

et al. (1986) and Ozhan et al. (2003) the RDX doses were unknown and so the doses were also 

optimized to fit the data. The model predictions for the Woody et al. (1986) data using the best fit 

values of dose = 58.9 mg/kg, KAS = 1.75/hour, and KfC = 9.87 kg0.33/hour are shown in Figure C-10. 

The model predictions for the Ozhan et al. (2003) data using the best fit values of an oral dose = 

3.5 mg/kg, KAS = 1.75/hour, and KfC = 9.87 kg0.33/hour are shown in Figure C-11. 

EPA’s calibration of the model differed in another important respect from that carried out 

by Sweeney et al. (2012a). As previously mentioned, Sweeney et al. (2012a) simulated the soldiers’ 

exposure from the Ozhan et al. (2003) study as an oral exposure, although the study report states 

that the exposure was via inhalation and dermal routes. An inhalation or dermal exposure could 

change the amount of RDX reaching the blood compared with an oral exposure due to first pass 

metabolism in the liver after oral absorption. Dermal absorption was not considered by EPA to be a 

significant route of RDX exposure and therefore was not modeled. This decision is supported by a 

study that used excised human skin and reported only 5.7% of the applied dose was absorbed into 

the skin by 24 hours post dosing (Reddy et al., 2008). The model was modified to simulate an 

inhalation exposure and compared with the data from Ozhan et al. (2003). There are insufficient 

data on blood: air partitioning to modify the Sweeney et al. (2012a) model with a lung 

compartment; therefore, inhalation exposure was modeled in an approximate manner as a direct 

input to the blood with an optimized absorption rate to represent absorption from air containing 

RDX into the blood. The soldiers’ inhalation exposure was simulated as a continuous 8-hour 

exposure (i.e., assuming that the soldiers were exposed occupationally during an 8-hour workday), 

and for the same dose of 3.5 mg RDX/kg that was estimated by Sweeney et al. (2012a). The model 

assumed 100% of the inhaled dose was absorbed and the absorption rate constant was optimized 

to fit the measured blood concentrations of RDX. The model predictions were in good agreement 

with the RDX blood concentrations reported by Ozhan et al. (2003) as shown in Figure C-11. 
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Figure C-10. EPA human model predictions fitted to observed RDX blood 

concentrations resulting from an accidental ingestion of RDX by a 14.5-kg boy

(Woody et al., 1986). The best fit values were KAS = 1.75/hour, dose = 58.9 mg/kg 

and KfC = 9.87 kg0.33/hour.

Figure C-11. EPA human model predictions fitted to observed RDX blood 

concentrations resulting from accidental exposure to adults assumed to be 

70 kg (Ozhan et al., 2003). For an assumed oral exposure the best fit values were 

KAS = 1.75/hour, dose = 3.5 mg/kg and KfC = 9.87 kg0.33/hour. For the same 

3.5 mg/kg dose and metabolism rate constant an inhalation exposure found a best 

fit value for Klung of 0.75/hour. 

Sensitivity Analysis of the Rat and Human PBPK Models 

A sensitivity analysis was performed to see how each model parameter affects the model 

output. A sensitivity coefficient, defined as the change in a specified dose metric due to a 1% 

increase in the value of a parameter, was calculated for each parameter in the rat and human 

models. This analysis was carried out for both short (24 hours following a single oral dose of 

1.5 mg/kg RDX) and longer term (90 days of repeated oral dosing with 1.5 mg/kg RDX) exposures 

for the dose metric of blood area-under-the-curve (AUC). Parameters with sensitivity coefficients 
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1 greater than 0.1 in absolute value (i.e., considered sensitive) are presented in Table C-8. For the 

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blood AUC dose metric the only sensitive RDX-specific parameter is the metabolic clearance rate 

(KfC). This sensitivity is likely because bioavailability was assumed to be 100% and metabolism is 

the only route of elimination in the model. These assumptions mean that all administered RDX will 

be absorbed and metabolized, in other words the blood AUC is proportional to the dose and 

inversely proportional to the metabolic clearance rate constant. For the parameter values in this 

model the rate of metabolism is relatively slow compared to the transport of RDX between other 

tissues and the site of metabolism in the liver, so that the blood AUC is not sensitive to parameters 

that impact transport such as KQC and KQL. Because the metabolic clearance rate constant is 

scaled to BW and by liver volume, the blood AUC is also sensitive to these parameters. The 

sensitivity analysis by Sweeney et al. (2012b) for the AUC of RDX in the liver found the model was 

sensitive to the liver:blood partition coefficient (PL) in addition to the same parameters (KfC, KVL 

and BW) found for the blood AUC.

The model is also very sensitive to oral bioavailability with a sensitivity coefficient of 0.8 in 

the case of the rat model. As discussed above in the oral absorption section of toxicokinetics (C.2.1), 

estimates of the bioavailability of RDX range from 50 to 87% or greater and may depend upon the 

physical form of RDX (Krishnan et al., 2009; Schneider et al., 1978, 1977). However, as seen in 

Figure C-5, it was not possible to identify the bioavailability and the absorption rate (KAS) as 

separate parameters by fitting to the available RDX blood concentration time course. Introducing 

oral bioavailability as an additional unknown parameter and recalibrating the model did not appear 

to provide an advantage. Therefore, 100% bioavailability was assumed in the model and 

acknowledged as an uncertainty. 

Table C-8. Sensitivity coefficients for rat and human RDX PBPK models

Parameter Rat sensitivity coefficient Human sensitivity coefficient

Fractional liver volume (KVL) −1 −1

Body weight (BW) 0.3 0.3

Metabolic rate constant (KfC) −1 −1

Parameters with sensitivity coefficients < 0.1 in absolute value are considered not sensitive, and are listed below:

cardiac output (KQC);

fractional blood flow to all tissues (liver, KQL; fat KQF; slowly perfused tissues KQS; brain KQB);

fractional tissue volume of fat (KVF), brain (KVB), and blood volume (KVV);

blood partition coefficients to all tissues (liver PL, fat PF, rapidly perfused PR, slowly perfused PS, brain PB);

absorption rates from GI (KAS, KT, KAD)

Simulating Exposures in Mice

Physiological parameters specific to mice were obtained from the literature (Brown et al., 

1997) and are shown in Table C-6. The partition coefficients calculated for mice by Sweeney et al. 
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1 (2012b) were used, which includes the liver, brain, and richly perfused tissues. The partition 

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coefficients for the fat and slowly perfused tissues from the Sweeney et al. (2012b) mouse model 

were not used because they were estimated via optimization of fits to rat iv data. Instead the 

partition coefficient for fat tissues was set equal to the value calculated by Krishnan et al. (2009) for 

rat fat tissue, 7.55. The partition coefficient for slowly perfused tissues (0.9) was calculated for 

mouse tissues using the same methodology as Krishnan et al. (2009). The rate constants for oral 

absorption and metabolism were optimized to fit the data from Sweeney et al. (2012b) for mouse 

blood RDX concentrations. The model predictions were in good agreement with the RDX blood 

concentrations reported by Sweeney et al. (2012b) as shown in Figure C-12. 

The only information on RDX metabolism in the mouse comes from a study by Pan et al. 

(2013). Pan et al. (2013) measured nitrosamine RDX metabolites of RDX (MNX, DNX, TNX, the 

latter representing a minor metabolic pathway) in mice at the end of a 28-day exposure to RDX in 

feed (ad libitum). These measurements were a single time point without controlling the time 

between the last RDX ingestion and measurement, and were therefore judged not to be sufficient 

for use in parameterizing a PBPK model of the nitrosamine metabolites. 

Figure C-12. Comparison of EPA mouse PBPK model predictions with data 

from oral exposure to RDX dissolved in water. Model fits and mean and 

standard deviation of observed RDX blood concentrations in female B6C3F1 mice 
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1 (0.0205 kg) for doses of 35, 60, and 80 mg/kg with KAS = 0.6/hour and KfC = 

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Summary of Confidence in PBPK Models for RDX

Overall, good fits to the rat, mouse, and human time-course data for RDX internal 

concentrations were obtained. For the rat and human models, calibration was based generally on 

fitting to more than one data set obtained from different studies originating in different 

laboratories or accidental exposure settings. Predictions from the rat model compared well with 

data from a subchronic drinking water study that was not used in model calibration. 

The metabolic rate constant used in the human model was fit to limited data from 

accidentally exposed humans; however, the value of the metabolic rate constant has additional 

support from in vitro experimental data. The rat metabolic rate constant, fit to multiple 

experimental data sets, was scaled to humans using the ratio of human to rat rate constants 

measured with in vitro methods. This scaled value of the human metabolic rate constant was very 

similar to the rate constant estimated by fitting the model to the human data. The congruence in 

values increases the confidence in using the EPA-modified PBPK model for predicting human blood 

RDX concentrations.

There are several uncertainties in these models, listed below, the most significant of which 

pertain to the mouse PBPK model. The mouse model was based on a single data set, which used 

high RDX doses to obtain detectable RDX blood concentrations, and the type of additional data that 

increased the confidence in the rat and human models are not available for mice. The additional

data not available for mice are the lack of in vitro measurements of RDX metabolism by mouse cells 

and lack of quantification of potential routes of RDX elimination in mice. Overall these 

uncertainties result in lower confidence in the mouse model than in the rat an human models. 

1) RDX is readily metabolized in several species, yet there are no data on the toxicokinetics of 

RDX metabolites in the rat and human. Some data are available for the n-nitrosoamine 

metabolites (a minor metabolic pathway) in mice, but the data are too sparse to help better 

parameterize a PBPK model. Consequently, the PBPK models used in this assessment do 

not incorporate the kinetics of RDX metabolites. 

2) The available toxicokinetic data are not sufficient to uniquely identify a parameter value for 

RDX oral bioavailability. Consequently the model assumes 100% bioavailability even 

though some studies in rats suggest a lower bioavailability is likely.

3) The human model is based on single accidental exposures, and the exposure concentrations 

are not known.

4) The only route of clearance of RDX used in the models is that of total metabolism, which 

appears reasonable for the rat for which only roughly 5% of the RDX was detected 

unmetabolized in urine and feces. However, no data on the excretion of RDX are available 

for the mouse. This inability to properly characterize the fraction of RDX that is 

metabolized in the mouse is problematic considering some evidence to indicate that the role 
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1 of metabolism in RDX toxicity may be different across species. This uncertainty decreases 

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the confidence in the mouse PBPK model. 

5) The PBPK model for the mouse is based on a single data set. This single data set is used to 

fit both the absorption and metabolic rate constants. There are no in vitro data to 

independently estimate the metabolic rate constant for the mouse. Consequently, the 

confidence in the mouse model parameter values is low. 

6) The analytical detection limit in the mouse pharmacokinetic study is too high to enable 

detection at the lower doses. The lowest dose at which RDX was detected was 35 mg/kg; 

this concentration was high enough to manifest some toxicity in the chronic mouse 

bioassay. The measured blood concentration at the 35 mg/kg dose is based on the level 

measured from one single animal (others were non-detects or excluded as outliers). This 

decreases the confidence in the calibration of the mouse PBPK model.

7) The metabolic rate constant as estimated by the PBPK model for mice was 30-fold higher 

than the rat (after accounting for body weight differences), suggesting the toxicokinetics of 

RDX could be significantly different in the mouse than in the rat. Mice may have more 

efficient or higher expression of the CYP P450 enzymes. Alternatively, mice may have other 

unknown metabolic pathways responsible for metabolizing RDX. Identifying the specific 

CYP enzymes, measuring expression levels, and in vitro metabolic rate constants in mice 

would allow for in vitro scaling from rats to mice, which could be used to independently 

evaluate the mouse metabolic rate constant. Given the high sensitivity of the model to the 

metabolic rate constant, this uncertainty in the mouse toxicokinetics significantly decreases 

confidence in using the mouse PBPK model for predicting mouse blood RDX concentrations. 

Model Code for RDX PBPK Model Used in the Assessment

The PBPK acslX model code is made available electronically through the HERO database. All 

model files may be downloaded in a zipped workspace from HERO at 

https://hero.epa.gov/index.cfm/project/page/project_id/2216; search for “RDX PBPK files in acsIX 

format.”

C.3. HUMAN STUDIES

Table C-9 presents a summary of case reports of humans acutely exposed to RDX. 

Table C-10 provides a summary of the methodologic features of the available epidemiology studies 

of RDX.
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1 Table C-9. Summary of case reports of exposure to RDX

Reference, 

number of cases, 

exposure setting Exposure Effects observed Comments

Barsotti and Crotti 

(1949) 

17 males among 

20 male Italian 

workers 

(1939−1942)

Manufacturing

Inhalation of RDX powder 

during the drying, cooling, 

sieving, and packing 

processes of its manufacture

Generalized convulsions of a 

tonic-clonic (epileptic) type 

followed by postictal coma; loss 

of consciousness without 

convulsions; vertigo; vomiting and 

confusion; transient arterial 

hypertension

Symptoms occurred either 

without prodromal symptoms or 

were preceded by several days of 

insomnia, restlessness, irritability, 

or anxiety

Tobacco and alcohol use 

were considered by the 

study authors to be 

aggravating factors

Kaplan et al. (1965)

5 males among 

26 workers (April−

July 1962)

Manufacturing

Inhalation, ingestion, and 

possible skin absorption as a 

result of the release of RDX 

dust into the workroom air 

during the dumping of dried 

RDX powder, screening and 

blending, and cleanup of 

spilled material without 

adequate ventilation 

Sudden convulsions or loss of 

consciousness without 

convulsions; few or no 

premonitory symptoms (e.g., 

headache, dizziness, nausea, 

vomiting); stupor, disorientation, 

nausea, vomiting, and weakness; 

no changes in complete blood 

counts or urinalysis

Mild cases of RDX 

intoxication may have 

been masked by viral 

illness with nonspecific 

symptoms (e.g., 

headache, weakness, 

upset gastrointestinal 

[GI] tract). No method 

was available for 

determining RDX 

concentrations in air; 

recovery was complete 

without sequelae

Merrill (1968)

2 males

Wartime, Vietnam

Ingestion of unknown 

quantity of C-4 with 

moderate amounts of alcohol

Coma, vomiting, hyperirritability, 

muscle twitching, convulsions, 

mental confusion, and amnesia; 

kidney damage (oliguria, gross 

hematuria, proteinuria, elevated 

blood urea nitrogen [BUN]); liver 

or muscle damage (high aspartate 

transaminase [AST]), leukocytosis

Confounding factors 

included ingestion of C-4 

while intoxicated with 

ethanol (vodka), which 

may have caused GI 

symptoms, and smoking 

(1−1.5 packs of 

cigarettes per day)

Stone et al. (1969)

4 males (March−

December 1968)

Wartime, Vietnam

Ingestion of 180 g (patient 1), 

or 25 g (patients 2, 3) of C-4 

(91% RDX)

Generalized seizures, lethargy, 

nausea, vomiting, fever, muscle 

soreness, headaches, twitching, 

(semi)comatose, headaches, 

hematuria, abnormal laboratory 

findings, muscle injury, elevated 

AST; no kidney damage

For the patient who ingested the 

highest dose, anemia and loss of 

recent memory present after 30 d

Troops ingested small 

quantities of RDX to get 

a feeling of inebriation 

similar to that induced 

by ethanol
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Reference, 

number of cases, 

exposure setting Exposure Effects observed Comments

Hollander and 

Colbach (1969)

5 males (June 

1968−January 1969)

Wartime, Vietnam

Inhalation (all 5 cases) and 

ingestion of unknown 

quantity of C-4 (2 cases)

Tonic-clonic seizures; nausea and 

vomiting occurred before and 

after admission; hyperirritability, 

muscle twitching, convulsions, 

mental confusion, and amnesia; 

kidney damage (oliguria, gross 

hematuria, proteinuria, elevated 

BUN); liver or muscle damage 

(high AST), leukocytosis; 

symptoms cleared by the next day 

except for amnesia (in case 2), 

oliguria (lasted for 4 d), and gross 

hematuria (decreased by 

9th hospital day)

Knepshield and 

Stone (1972)

6 males

Wartime, Vietnam

Ingestion of C-4, range 

25−180 g, average 77 g 

Generalized seizures, coma, 

lethargy, severe neuromuscular 

irritability with twitching and 

hyperactive reflexes, myalgia, 

headache, nausea, vomiting, 

oliguria, gross hematuria, lowgrade fever; abnormal laboratory 

findings (neutrophilic 

leukocytosis, azotemia, elevated 

AST)

Includes data on 

2 patients from Merrill 

(1968) 

Ketel and Hughes 

(1972)

18 males 

(December 

1968−December 

1969)

Wartime, Vietnam

Inhalation while cooking with 

C-4 and possible ingestion 

Central nervous system signs: 

confusion, marked 

hyperirritability, involuntary 

twitching of the extremities, 

severe prolonged generalized 

seizures, prolonged postictal 

mental confusion and amnesia, 

renal (oliguria and proteinuria; 

one case of acute renal failure 

requiring hemodialysis) and GI 

toxicity (nausea, vomiting)

C-4 was cut with the 

same knife used to 

stir/prep food

Woody et al. (1986)

1 male child (August 

1984)

Manufacturing

Ingestion of plasticized RDX 

from mother's clothing 

and/or boots; estimated 

ingested dose of 1.23 g RDX 

was normalized to the 

patient's body weight 

(84.82 mg/kg)

Seizures before and after 

admission; electroencephalogram 

(EEG) revealed prominent diffuse 

slowing that was greatest in the 

occipital regions with no evidence 

of epileptiform activity; elevated 

AST on admission and after 24 hr; 

within 24 hr the child was 

extubated and intensive care 

withdrawn; normal mental status 

and normal neurological 

examination at discharge

Mother worked at an 

explosive plant in which 

RDX was manufactured 

in a plasticized form
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Reference, 

number of cases, 

exposure setting Exposure Effects observed Comments

Goldberg et al. 

(1992)

1 male

Nonwartime

Ingestion after chewing a 

piece (unknown size) of 

“Semtex” plastic explosive 

4 hr before first seizure

Frontal headache and two tonicclonic seizures; progressively 

disseminating petechial rash 

suggestive of meningococcal 

infection apyrexial; normotensive; 

no photophobia; no neurological 

abnormalities; florid petechial 

rash over the face and trunk; 

lacerated tongue. Initial results 

included: leukocyte count of 

10.8 × 109

/dl (87% neutrophils); 

hemoglobin, platelet count, 

coagulation screen, serum and 

cerebrospinal fluid (CSF) 

biochemistry all within normal 

limits; CSF and blood 

bacteriologically unremarkable. 

Shortly following admission, his 

headache and rash disappeared. 

There were no further seizures

Harrell-Bruder and 

Hutchins (1995)

1 male

Nonwartime

Ingestion of C-4 (chewing on 

a piece of undetermined size)

Tonic-clonic seizures, postictal 

state, EEGs were normal; brisk 

deep tendon reflexes

Testud et al. 

(1996b)

1 male

Manufacturing

Inhalation and possible 

dermal exposure during the 

RDX manufacturing process

Malaise with dizziness, headache, 

and nausea progressing to 

unconsciousness and generalized 

seizures without involuntary 

urination or biting of the tongue. 

Blood chemistries were in the 

normal range and blood alcohol 

content was null. 

Testud et al. 

(1996a)

2 males

Manufacturing

Inhalation and possible 

dermal exposure during the 

RDX manufacturing process

Sudden loss of consciousness and 

generalized seizures; blood serum 

level of 2 mg/L RDX measured

Smoker and alcohol 

drinker

Hett and Fichtner 

(2002)

1 male 

Nonwartime

Ingestion of a cube (1 cm 

across) of C-4 

Nausea and vomiting, tonic-clonic 

seizure lasting 2 min, followed by 

two seizures of about 30 sec each; 

myoclonic jerks in all limbs; 

petechial hemorrhages around 

face and trunk after seizures
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Reference, 

number of cases, 

exposure setting Exposure Effects observed Comments

Küçükardali et al. 

(2003)

5 males

Nonwartime

Ingestion (accidental) of 

37−250 mg/kg body weight 

RDX during military training 

via food contaminated with 

RDX 

Abdominal pain, nausea, 

vomiting, myalgia, headache, 

generalized weakness, repetitive 

tonic-clonic convulsions, lethargic 

or comatose between seizures, 

hyperactive deep tendon reflexes, 

sinusal tachycardia. Elevated 

serum levels of AST and ALT. 

Kidney damage was observed. 

Plasma RDX levels 3 hr after 

ingestion ranged from 268 to 

969 pg/mL.

Davies et al. (2007)

17 males

Nonwartime

Ingestion of unknown 

quantity C-4 under unclear 

circumstances, but unrelated 

to recreational abuse 

Seizures, headache, nausea and 

vomiting; hypokalemia and 

elevated creatine kinase, lactate 

dehydrogenase, and phosphate 

were noted in all but two 

patients. Metabolic acidosis only 

occurred in two patients directly 

following seizures

Patient histories may 

have been affect by the 

fact that the incident 

was the focus of a 

military police 

investigation

Kasuske et al. 

(2009)

2 males

Nonwartime

Ingestion of C-4 after 

handling explosive ordnance 

Seizures, postictal state, 

confusion, drowsiness, headache, 

nausea and vomiting. Blood work 

revealed high white blood cell 

count and elevated creatine 

phosphokinase). Proteinuria and 

gross hematuria were observed.

 1 
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1 Table C-10. Epidemiologic studies of RDX: summary of methodologic features

Reference, 

setting and 

design

Participants, 

selection, 

follow-up

Consideration 

of likely 

selection bias

Exposure 

measure and 

range

Outcome 

measure

Consideration of 

likely 

confounding

Analysis and 

results details Sample size 

Occupational exposure studies

Ma and Li 

(1992)

(China)a

Industrial 

workers

Translated 

article

Details of 

industrial 

process and 

subject selection 

framework not 

reported. 

Referents 

chosen from 

same plant; age, 

employment 

duration, and 

education 

similar across 

groups. 

Participation 

rate, NR.

Sparse reporting 

of details on 

subject 

recruitment and 

participation. 

Details of exposure 

monitoring not 

reported. Two 

groups of exposed 

subjects: 

Group A, intensity, 

0.407 (0.332) 

mg/m3 [mean (SD)], 

daily cumulative, 

2.66 (1.89) mg/m3

. 

Group B, intensity, 

0.672 (0.556) 

mg/m3

; daily 

cumulative, 

2.53 (8.40) mg/m3

. 

Neurobehavioral 

battery 

administered by 

trained 

personnel—

memory retention, 

simple reaction 

time, choice 

reaction time, 

letter cancellation, 

block design. 

No adjustment for 

other risk factors, 

e.g., alcohol 

consumption. No 

consideration or 

attempt to 

distinguish TNT.

Comparisons of 

mean scaled 

score on memory 

retention, letter 

cancellation, or 

block design test; 

mean time on 

reaction tests; 

and total 

behavioral score. 

Variance (F test), 

linear and 

multiple 

regression, and 

correlation 

analysis.

60 exposed; Group A 

(n = 30; 26 males, 

4 females); Group B 

(n = 30); 32 referents 

(27 males, 5 females).

Hathaway 

and Buck 

(1977); 

(United 

States)

Ammunition 

workers

2022 workers 

(1,017 exposed 

to open 

explosives (TNT, 

RDX, HMX), 

1,005 referents) 

at five U.S. Army 

ammunition 

plants (IA, IL, 

TN). 

Participation 

rate, 76% 

Potential 

healthy worker 

effect. 

Atmospheric 

samples of all 

operations with 

potential exposure 

to open explosives 

taken in 1975. 

Range: 

ND−1.57 mg/m3

. 

70 exposed workers 

with RDX at 

>0.01 mg/m3 [the 

LOD]; mean: 

0.28 mg/m3 [SD not 

Liver function, 

renal function, and 

hematology tests 

[blood].

Workers with TNT 

exposure excluded 

from exposed 

groups. 

Comparison of 

mean value; 

prevalence of 

elevated value on 

an individual test. 

69 RDX exposed 

(43 males, 

26 females), 

24 RDX/HMX exposed 

(all males), 338 

referents (237 males, 

101 females).
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Reference, 

setting and 

design

Participants, 

selection, 

follow-up

Consideration 

of likely 

selection bias

Exposure 

measure and 

range

Outcome 

measure

Consideration of 

likely 

confounding

Analysis and 

results details Sample size 

exposed, 71% 

referents. 

presented]. Job 

title used to initially 

identify exposed or 

unexposed status 

and reassigned to 

one of two exposed 

groups 

(nondetected, 

>0.01 mg/m3

) based 

on subject’s IH 

monitoring results.

West and 

Stafford 

(1997); 

(United 

Kingdom)

Ammunition 

workers

(Case-control 

study)

378 of 

404 subjects 

(excluded 

3 deaths and 23 

subjects with 

unknown 

addresses) 

previously 

studied in 1991, 

32 cases with 

abnormal 

hematology test 

and 322 controls 

with normal 

hematology test.

Participation 

rate among 

eligible subjects, 

97% cases, 93% 

controls.

Former 

employees who 

were unable to 

work due to 

adverse health 

outcome were 

not included in 

the 1991 

prevalence 

study.

Semiquantitative 

assessment; source 

of IH data not 

reported. 

Interviews with 

current and past 

employees and job 

title analysis to 

identify potential 

exposure to 100 

agents, including 

RDX. Exposure 

surrogate was 

>50 hrs duration 

and intensity (low 

[1−10 ppm], 

moderate 

[10−100 ppm], and 

high 

[100−1,000 ppm]). 

RDX exposure 

Abnormal 

hematology value 

in 1991 survey 

indicating possible 

meylodysplasia:

neutropenia (2.0 x 

109/l), low platelet 

count (<150 x 

109/l), or 

macrocytosis 

(mean corpuscular 

volume = 99 fl or 

>6% macrocytes). 

Cases and controls 

are not matched 

and statistical 

analyses are not 

adjusted for other 

risk factor or 

occupational 

exposures. No 

consideration or 

attempt to 

distinguish TNT

Unadjusted 

prevalence odds 

ratios and 95% 

CIs. Analyses 

limited to males 

because of low 

frequency of 

exposure to 

females.

32 cases (29 males, 3 

females) and 322 

controls (282 males, 

12 females).
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Reference, 

setting and 

design

Participants, 

selection, 

follow-up

Consideration 

of likely 

selection bias

Exposure 

measure and 

range

Outcome 

measure

Consideration of 

likely 

confounding

Analysis and 

results details Sample size 

prevalence (males), 

83%.

1 

2 

3 

4 

5 

6 

a

Ma and Li (1992) describes symptoms reported by subjects during a physical examination but are not included in the evidence table because responses for 

individual symptoms were not identified. 

ATSDR = Agency for Toxic Substances and Disease Registry, HMX = cyclotetramethylenetetranitramine, IA = Iowa, IL = Illinois, mg/m3 = milligram/cubic meter, 

ND = not detected, SD = standard deviation, TN = Tennessee, TNT = trinitrotoluene
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1 C.4. OTHER PERTINENT TOXICITY INFORMATION

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Genotoxicity

RDX. RDX has tested negative in a variety of in vitro tests for genotoxicity, including 

mutation assays in multiple strains of Salmonella typhimurium (with or without metabolic 

activation), recombination in Saccharomyces cerevisiae strain D3, and forward mutations in both 

V79 Chinese hamster lung cells and mouse lymphoma L5178Y cells. However, in genotoxicity 

assays designed to be more sensitive, RDX did show some positive results. For example, when the 

concentration of S9 was doubled, the mutagenicity of RDX was about twice that of background. 

RDX also showed positive mutagenic results with metabolic activation in a chemiluminescent assay 

(Mutatox assay). In some cases, the interpretation of testing data for RDX was complicated by the 

tendency of the compound to precipitate out of DMSO solution (the usual vehicle) at concentrations 

≥250 μg/mL (Reddy et al., 2005). As with other studies of RDX, the purity of the test compound 

was unknown in several (particularly older) studies. A summary of the results of in vitro 

genotoxicity studies of RDX is presented in Table C-11. 

RDX has produced negative results in all reverse mutation assays in S. typhimurium that use 

standard levels of the metabolic activation system (S9). No evidence of reverse mutation was 

observed in S. typhimurium (strains TA98, TA100, TA1535, TA1537, and TA1538), either with or 

without the addition of S9 metabolic activating mixture (Neuwoehner et al., 2007; George et al., 

2001; Lachance et al., 1999; Tan et al., 1992; Minor et al., 1982; Cholakis et al., 1980; Whong et al., 

1980; Simmon et al., 1977a). One exception is a finding of weak mutagenic activity of RDX to S. 

typhimurium strain TA97a (mutagenicity index = 1.5−2.0) (Pan et al., 2007a). However, this assay 

used a high percentage of S9 fraction (9% instead of 4%), indicating that extensive metabolic 

activation is needed to elicit a mutagenic response. 

RDX did not cause gene recombination in S. cerevisiae strain D3 at concentrations up to 

23 μg/mL, with or without metabolic activation (Simmon et al., 1977a). The study authors noted 

that the negative findings should be considered in the context of the low concentrations tested. 

Similarly, RDX did not induce forward mutations (HGPRT locus) in V79 Chinese hamster lung cells, 

with or without metabolic activation, although minimal cytotoxicity was observed at 180 μM

(Lachance et al., 1999). However, RDX produced revertants in two of three trials in the Mutatox 

assay with the bacterium V. fisheri when tested at doses up to 2.5 μg/tube, with and without S9

(Arfsten et al., 1994). In the presence of S9, a dose-response was observed; in the absence of S9, no 

dose-response relationship was detected (Arfsten et al., 1994). RDX did not induce forward 

mutations in mouse lymphoma L5178Y cells with or without metabolic activation (Reddy et al., 

2005). During an accompanying range-finding study, precipitates occurred at doses ≥250 μg/mL, 

suggesting that concentrations of RDX in DMSO reported beyond 250 μg/mL may not be accurate.

RDX did not induce unscheduled DNA synthesis, with or without metabolic activation, using 

human diploid fibroblasts (WI-38 cells) when tested in DMSO at concentrations up to 4,000 μg/mg; 
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1 however, precipitation of RDX at high concentrations in cell culture media makes interpretation of 

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these results difficult (Dilley et al., 1979). Only two in vivo studies are available for the genotoxicity 

of RDX; these are summarized in Table C-12. RDX did not decrease the ratio of polychromatic 

erythrocytes (PCE) to normochromatic erythrocytes (NCE), nor did it induce micronucleated PCEs 

in an in vivo mouse bone marrow micronucleus assay in young adult male CD-1 mice (Reddy et al., 

2005). RDX was considered negative for the induction of dominant lethal mutations in male CD rats 

fed RDX at nominal doses from 0 to 50 mg/kg-day for 15 weeks prior to mating with untreated 

virgin females (Cholakis et al., 1980). Females sacrificed at midgestation showed no statistically 

significant effects on number of corpora lutea, implants, or the number of live or dead embryos

(Cholakis et al., 1980). 

Metabolites of RDX. Several metabolites of RDX, N-nitroso derivatives of the parent 

compound (mononitroso, dinitroso, and trinitroso compounds, abbreviated MNX, DNX, and TNX, 

respectively) (Musick et al., 2010; Major et al., 2007), have been tested directly for genotoxicity

(Pan et al., 2007a; George et al., 2001; Snodgrass, 1984). Miniature pigs were used to detect these 

trace metabolites because the swine model of the GI tract more closely resembles that of humans

(Major et al., 2007); an identification and quantification of RDX metabolites in humans has not been 

conducted. A summary of the results of in vitro and in vivo genotoxicity studies of metabolites of 

RDX is presented in Table C-13. 

Pan et al. (2007a) studied the mutagenicity of two metabolites, MNX and TNX. These 

metabolites were not mutagenic in TA97a at normal levels of S9 but clearly mutagenic at enhanced 

concentrations of S9 (4% versus 9% S9). The observation that these metabolites were positive in 

TA97a is likely due to this strain’s higher sensitivity for frameshift mutations that occur at a cluster 

of cytosine residues in the mutated gene for histidine synthesis in this strain (Pan et al., 2007a). 

These metabolites were also weakly mutagenic in TA102, again with high levels of S9. Strain TA102 

was developed with an A:T base pair at the site of mutation and its sensitivity was increased by the 

addition of some 30 copies of a plasmid containing the mutant gene that is available for back 

mutation. This strain is sensitive to many oxidative mutagenic compounds (Levin et al., 1982). 

Other metabolites with potential human relevance identified in the urine of miniature pigs have not 

been assessed for their genotoxicity (Major et al., 2007). 

The genotoxicity of MNX was positive in three out of five assays conducted for the U.S. Army

(Snodgrass, 1984). MNX was positive with or without metabolic activation in the mouse lymphoma 

forward mutation assay at the thymidine kinase locus, for chromosomal aberrations in Chinese 

hamster ovary cells, and in the primary rat hepatocyte unscheduled DNA synthesis assay. MNX was 

not considered positive in S. typhimurium (strains TA98, TA100, TA1535, TA1537, and TA1538), 

either with or without the addition of S9 metabolic activating mixture or in an in vivo dominant 

lethal mutation assay in mice. However, this study is of limited use due to a significant lack of 

details including information on dosing, raw data, and statistical reporting. 
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1 In summary, RDX is not mutagenic or genotoxic in vitro or in vivo in typical assays used to 

2

3 

4 

detect genotoxicity. In two in vitro studies using more sensitive assays and conditions for detecting 

mutagenicity, RDX was found to be positive. Several studies showed that the N-nitroso metabolites 

are genotoxic, but the formation and quantification of these metabolites in humans is not known. 
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1 Table C-11. Summary of in vitro studies of the genotoxicity of RDX

Endpoint Test system

Dose/

concentrationa

Resultsb

Comments Reference

Without 

activation

With 

activation

Genotoxicity studies in prokaryotic organisms

Reverse

mutation

Salmonella typhimurium

TA1535, TA1537, TA1538, TA98, 

TA100

1,000 μg/plate − − Metabolic activation with S9 Cholakis et al. 

(1980)

Reverse 

mutation

S. typhimurium TA1535, 

TA1537, TA1538 TA100, TA98

14 μg/plate − − Effect of disinfection treatments on 

mutagenicity tested: RDX was not mutagenic 

in any strain before or after disinfection 

treatment with chlorine or ozone 

Simmon et al. 

(1977b)

Reverse

mutation 

S. typhimurium TA98, TA100 250 μg/plate − − Study authors noted that results were 

consistent with literature

George et al. 

(2001)

Reverse 

mutation

S. typhimurium TA98, TA100 1 mg/plate − − Metabolic activation with S9 Tan et al. 

(1992)

Reverse

mutation

S. typhimurium TA98, TA100 1,090 μg/plate − − High S9 activation (9%) used Pan et al. 

(2007a)

Reverse

mutation

S. typhimurium TA97a 32.7 μg/plate − ± High S9 activation (9%) used; study authors 

concluded that RDX “required intensive

metabolic activation” to exhibit mutagenicity 

in this strain 

Pan et al. 

(2007a)

Reverse 

mutation

Vibrio fischeri 0.004 μg/tube ± + Mutatox assay with metabolic activation (S9) Arfsten et al. 

(1994)

Reverse 

mutation (umu

test)

Salmonella choleraesius subsp. 

chol. (prior Salmonella 

typhimurium) TA1535/pSK1002 

20.6 μg/mL − − No observed effect concentration; tested at 

highest concentration where the induction 

rate was below 1.5 for the first time and the 

growth factor was below 0.5

Neuwoehner 

et al. (2007)
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Endpoint Test system

Dose/

concentrationa

Resultsb

Comments Reference

Without 

activation

With 

activation

Reverse 

mutation

(NM2009 test)

S. choleraesius subsp. chol. 

NM2009, 

TA1535/pSK1002/pNM12

20.6 μg/mL − − No observed effect concentration; tested at 

highest concentration where the induction 

rate was below 1.5 for the first time and the 

growth factor was below 0.5

Neuwoehner 

et al. (2007)

Induction of

the sfiA gene 

(SOS 

chromotest)

Escherichia coli PQ37 20.6 μg/mL − − No observed effect concentration; tested at 

highest concentration where the induction 

rate was below 1.5 for the first time and the 

growth factor was below 0.5

Neuwoehner 

et al. (2007)

Reverse 

mutation

S. typhimurium, TA98, TA100 24.8 μg/mL − − No observed effect concentration; metabolic 

activation with S9

Neuwoehner 

et al. (2007)

Reverse 

mutation 

S. typhimurium TA98, TA100 2.6 μg/mL − − No observed effect concentration; metabolic 

activation with S9; minimal cytotoxicity was 

observed at 180 μM

Lachance et al. 

(1999)

Reverse 

mutation

S. typhimurium TA1535, 

TA1536, TA1537, TA1538 

TA100, TA98

30.8 μg/mL − − Metabolic activation with S9 Cotruvo et al. 

(1977)

Genotoxicity studies in nonmammalian eukaryotic organisms

Recombination 

induction

S. cerevisiae D3 23 μg/mL − − Study authors concluded that this 

microorganism did not appear to be useful 

for detecting mutagenicity in several 

compounds tested

Simmon et al. 

(1977b)

Recombination 

induction

S. cerevisiae D3 30.8 μg/mL − − Metabolic activation with S9 Cotruvo et al. 

(1977)

Genotoxicity studies in mammalian cells

Forward 

mutation

Chinese hamster lung 

fibroblasts V79 cells

40 μg/mL − − Minimal cytotoxicity observed at 40 μg/mL

(limit of solubility)

Lachance et al. 

(1999)
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Endpoint Test system

Dose/

concentrationa

Resultsb

Comments Reference

Without 

activation

With 

activation

Mutation L5178Y mouse lymphoma cells 500 μg/mL − − No or low cytotoxicity seen at these 

concentrations; however, precipitate was 

observed >250 μg/mL

Reddy et al. 

(2005)

Unscheduled 

DNA synthesis; 

DNA repair

WI-38 cells, human diploid 

fibroblasts

4,000 μg/mL − − Precipitates were observed at concentrations 

of RDX ≥40 μg/mL

Dilley et al. 

(1979)

1 

2 

3 

a

Lowest effective dose for positive results; highest dose tested for negative results.

b

+ = positive; ± = equivocal or weakly positive; − = negative. 
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1 Table C-12. Summary of in vivo studies of the genotoxicity of RDX

Endpoint Test system

Dose/

concentration Results Comments Reference

In vivo genotoxicity studies in mammalian systems

Micronucleus 

formation

CD-1 mouse bone marrow Single dose of 62.5, 

125, or 250 mg/kg

No significant decrease in 

PCE:NCE ratios; no 

induction of 

micronucleated PCE at any 

dose

250 mg/kg was maximum 

tolerated dose determined in 

dose range-finding study

Reddy et al. (2005)

Dominant 

lethal 

mutations

Male CD rats dosed and mated with 

untreated female rats

0, 5, 16, or 

50 mg/kg-d for 

15 wk

No statistically or 

biologically significant 

effects on fertility; 

determined to be negative 

for the induction of lethal 

mutations

Males in the high-dose group 

experienced lower food 

consumption and weight gain 

compared with all other 

groups

Cholakis et al. 

(1980)

2 

3 
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1 Table C-13. Summary of in vitro and in vivo studies of the genotoxicity of RDX metabolites

Endpoint Test system

Dose/

concentrationa

Resultsb

Comments Reference

Without 

activatio

n

With 

activatio

n

Genotoxicity studies in prokaryotic organisms

Reverse

mutation

Salmonella typhimurium TA97a, 

TA102

22 μg/plate − + Mono and trinitroso metabolites (MNX and 

TNX); high S9 activation (9%) used

Pan et al. (2007a)

Reverse

mutation

S. typhimurium TA1535, 

TA1537, TA1538, TA98, TA100

500 μg/plate + + Positive only for TNX; MNX and DNX were 

negative

George et al. 

(2001)

Reverse 

mutation

S. typhimurium TA1535, 

TA1537, TA1538, TA98, TA100

NR − − Mononitroso metabolite, MNX; metabolic 

activation with S9

Snodgrass (1984)

Genotoxicity studies in mammalian cells—in vitro

Forward 

mutation

Mouse lymphoma thymidine 

kinase 

NR + + Mononitroso metabolite, MNX; metabolic 

activation with S9

Snodgrass (1984)

Chromosomal 

aberrations

Chinese hamster ovary cells NR − + Mononitroso metabolite, MNX; metabolic 

activation with S9

Snodgrass (1984)

Unscheduled 

DNA synthesis; 

DNA repair

Primary rat hepatocytes NR + ND Mononitroso metabolite, MNX; additional 

metabolic activation not required with S9

Snodgrass (1984)

In vivo genotoxicity studies in mammalian systems

Dominant 

lethal 

mutations

Male mice dosed and mated 

with untreated female mice

NR − ND Mononitroso metabolite, MNX; additional 

metabolic activation not required with S9

Snodgrass (1984)

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3 

4 

5 

6 

a

Lowest effective dose for positive results; highest dose tested for negative results. b

+ = positive; ± = equivocal or weakly positive; − = negative.

ND = not determined, NR = not reported
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1 

APPENDIX D. DOSE-RESPONSE MODELING FOR 

THE DERIVATION OF REFERENCE VALUES FOR 

EFFECTS OTHER THAN CANCER AND THE 

DERIVATION OF CANCER RISK ESTIMATES

2 This appendix provides technical detail on dose-response evaluation and determination of 

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points of departure (POD) for relevant toxicological endpoints. The endpoints were modeled using 

the EPA’s Benchmark Dose Software (BMDS, Versions 2.4). Sections D.1 (noncancer) and D.2Error! 

Reference source not found. (cancer) describe the common practices used in evaluating the 

model fit and selecting the appropriate model for determining the POD, as outlined in the

Benchmark Dose Technical Guidance Document (U.S. EPA, 2012). In some cases it may be 

appropriate to use alternative methods, based on statistical judgement; exceptions are noted as 

necessary in the summary of the modeling results.

D.1. BENCHMARK DOSE MODELING SUMMARY FOR NONCANCER

ENDPOINTS

The noncancer endpoints that were selected for dose-response modeling are presented in 

Table D-1. For each endpoint, the doses and response data used for the modeling are presented. 

Table D-1. Noncancer endpoints selected for dose-response modeling for RDX

Endpoint and 

reference Species/sex Dose

Incidence/total (%) or

mean ± SD (number of animals)

Convulsions

Crouse et al. (2006)a 

Female F344 

rat

0 mg/kg-d

4 

8 

10

12

15

0/10 (0%)

0/10 (0%)

2/10 (20%)

3/10 (30%)

5/10 (50%)

5/10 (50%)

Male F344 rat 0 mg/kg-d

4 

8 

10

12

15

0/10 (0%)

0/10 (0%)

1/10 (10%)

3/10 (30%)

8/10 (80%)

7/10 (70%)
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Endpoint and 

reference Species/sex Dose

Incidence/total (%) or

mean ± SD (number of animals)

Male and 

female F344 

rat, combined

0 mg/kg-d

4 

8 

10

12

15

0/20 (0%)

0/20 (0%)

3/20 (15%)

6/20 (30%)

13/20 (65%)

12/20 (60%)

Convulsions

Cholakis et al. (1980)

Female F344 

rat

(gestational 

exposure)

0 mg/kg-d

0.2

2 

20

0/24 (0%)

0/24 (0%)

1/24 (4%)

18/24 (75%)

Testicular degeneration

Lish et al. (1984); 

Male B6C3F1

mouse

0 mg/kg-d

1.5

7 

35

107

0/63 (0%)

2/60 (3%)

2/62 (3%)

6/59 (10%)

3/27 (11%)

Prostate suppurative 

inflammation

Levine et al. (1983)

Male F344 rat 0 mg/kg-d

0.3

1.5

8 

40

2/54 (4%)

4/55 (7%)

9/52 (17%)

12/55 (22%)

19/31 (61%)

1 

2 

3 

4 

5 

6 

7 

8 

9 

10

11

12

13

14

15

16

a

For convulsions in Crouse et al. (2006), the incidence rates across doses were determined to be not statistically 

significantly different between the males and females using an exact Cochran-Mantel-Haenszel test (p ≥ 0.10). 

The data were combined across sex for this endpoint prior to modeling. b

The high dose group was excluded from modeling because a large proportion (approximately half) of the mice in 

that group died before wk 11, when the dose was reduced from 175 to 100 mg/kg-d.

D.1.1. Evaluation of Model Fit

For each dichotomous endpoint, BMDS dichotomous models4 were fitted to the data using 

the maximum likelihood method. Each model was tested for goodness-of-fit using a chi-square 

goodness-of-fit test (χ2 p-value < 0.10 indicates lack of fit). Other factors were also used to assess 

model fit, such as scaled residuals, visual fit, and adequacy of fit in the low-dose region and in the 

vicinity of the BMR.

D.1.2. Model Selection

For each endpoint, the BMDL estimate (95% lower confidence limit on the BMD, as 

estimated by the profile likelihood method) and AIC value were used to select a best-fit model from 

among the models exhibiting adequate fit. If the BMDL estimates were “sufficiently close,” that is, 

 

4Unless otherwise specified, all available BMDS dichotomous models besides the alternative and nested 

dichotomous models were fitted. The following parameter restrictions were applied: For the log-logistic 

model, restrict slope ≥ 1; for the gamma and Weibull models, restrict power ≥1. 
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1 differed by at most threefold, the model selected was the one that yielded the lowest AIC value. If 

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the BMDL estimates were not sufficiently close, the lowest BMDL was selected as the POD.

D.1.3. Modeling Results

Below are tables summarizing the modeling results for the noncancer endpoints modeled. 

Nervous System Effects

Tables D-2 to D-10 present the BMD model results for incidence of convulsions for female, 

male, and male and female F344 rats combined based on data from Crouse et al. (2006), using 

BMRs of 10%, 5%, and 1% extra risk. Tables D-11 to D-13 present the BMD model results for 

incidence of convulsions for female F344 rats based on data from Cholakis (1980), using BMRs of 

10%, 5%, and 1% extra risk.

Table D-2. Model predictions for convulsions in female F344 rats exposed to 

RDX by gavage for 90 days (Crouse et al., 2006); BMR = 10% extra risk

Modela

Goodness of fit BMD10Pct

(mg/kg/d)

BMDL10Pct

p-value AIC (mg/kg/d) Basis for model selection

Gamma 0.923 55.085 6.46 2.92 The quantal-linear model was 

selected based on lowest BMDL 

(BMDLs differed by more than 

threefold). 

Logistic 0.733 56.607 6.76 4.75

LogLogistic 0.929 55.076 6.42 3.04

Probit 0.793 56.086 6.64 4.54

LogProbit 0.952 54.798 6.54 3.39

Weibull 0.892 55.420 6.16 2.62

Multistage 2° 0.954 53.595 5.46 2.47

Quantal-Linear 0.733 56.131 2.76 1.84

Multistage 5°b 0.885 55.525 5.98 2.47

Multistage 4° 0.885 55.525 5.98 2.47

Multistage 3° 0.885 55.525 5.98 2.49

Dichotomous-Hill 0.964 56.265 7.10 5.75

a

Selected model in bold; scaled residuals for selected model for doses 0, 4, 8, 10, 12, and 15 mg/kg-d were 0.00, 

−1.29, −0.46, −0.12, 0.87, and 0.41, respectively. b

The Multistage 5° model may appear equivalent to the Multistage 4° model, however differences exist in digits 

not displayed in the table.
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1 

2 

3

4 

5 

 0

 0.1

 0.2

 0.3

 0.4

 0.5

 0.6

 0.7

 0.8

 0 2 4 6 8 10 12 14

Fraction Affected

dose

Quantal Linear Model, with BMR of 10% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the 

14:08 02/27 2014

BMDL BMD

 

Quantal Linear

Figure D-1. Plot of incidence rate by dose, with fitted curve for selected model, 

for convulsions in female F344 rats exposed to RDX by gavage for 90 days 

(Crouse et al., 2006). BMR = 10% extra risk; dose shown in mg/kg-day.
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1 Quantal Linear Model using Weibull Model. (Version: 2.16; Date: 2/28/2013)

2

3 

4 

5 

6 

7 

8 

9 

10

11

12

13

14

15

16

17

18

1

2

9

0

The form of the probability function is: P[response] = background + (1-background)*[1-

EXP(-slope*dose)] 

Benchmark Dose Computation

BMR = 10% Extra risk

BMD = 2.75544

BMDL at the 95% confidence level = 1.84489

Parameter Estimates

Variable Estimate Default initial parameter values

Background 0 0.0833333

Slope 0.0382372 0.0404091

Power n/a 1

Analysis of Deviance Table

Model Log(likelihood)

Number of

parameters Deviance

Test degrees of 

freedom p-value

Full model −24.9756 6

Fitted model −27.0654 1 4.17949 5 0.5239

Reduced model −33.7401 1 17.529 5 0.003598

AIC: = 56.1307

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0 0 0 10 0

4 0.1418 1.418 0 10 −1.286

8 0.2635 2.635 2 10 −0.456

10 0.3178 3.178 3 10 −0.121

12 0.368 3.68 5 10 0.866

15 0.4365 4.365 5 10 0.405

Chi^2 = 2.79 d.f = 5 P-value = 0.7325
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This document is a draft for review purposes only and does not constitute Agency policy.

D-6 DRAFT―DO NOT CITE OR QUOTE

1 Table D-3. Model predictions for convulsions in female F344 rats exposed to 

2 RDX by gavage for 90 days (Crouse et al., 2006); BMR= 5% extra risk

Modela

Goodness of fit BMD5Pct

(mg/kg-d)

BMDL5Pct

p-value AIC (mg/kg-d) Basis for model selection

Gamma 0.923 55.085 5.09 1.54 The quantal-linear model was 

selected based on lowest BMDL 

(BMDLs differed by more than 

threefold). 

Logistic 0.733 56.607 4.76 2.83

LogLogistic 0.929 55.076 4.99 1.71

Probit 0.793 56.086 4.80 2.69

LogProbit 0.952 54.798 5.33 2.17

Weibull 0.892 55.420 4.55 1.30

Multistage 2° 0.954 53.595 3.81 1.21

Quantal-Linear 0.733 56.131 1.34 0.898

Multistage 3° 0.885 55.525 4.30 1.21

Multistage 4°b 0.885 55.525 4.30 1.21

Multistage 5° 0.885 55.525 4.30 1.20

Dichotomous-Hill 0.964 56.265 6.25 2.30

3 

4 

5 

6 

7 

8 

9 

a

Selected model in bold; scaled residuals for selected model for doses 0, 4, 8, 10, 12, and 15 mg/kg-d were 0.00, 

−1.29, −0.46, −0.12, 0.87, and 0.41, respectively. The BMD10 and BMDL10 for the selected model were 2.76 and 

1.84 mg/kg-d, respectively. b

The Multistage 4° model may appear equivalent to the Multistage 3° model, however differences exist in digits 

not displayed in the table.
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-7 DRAFT―DO NOT CITE OR QUOTE

1 

2 

3

4 

5

6

7 

8 

9 

10

11

12

13

14

15

16

17

 0

 0.1

 0.2

 0.3

 0.4

 0.5

 0.6

 0.7

 0.8

 0 2 4 6 8 10 12 14

Fraction Affected

dose

Quantal Linear Model, with BMR of 5% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the B

14:07 02/27 2014

BMDL BMD

 

Quantal Linear

Figure D-2. Plot of incidence rate by dose, with fitted curve for selected model, 

for convulsions in female F344 rats exposed to RDX by gavage for 90 days 

(Crouse et al., 2006). BMR= 5% extra risk; dose shown in mg/kg-day.

Quantal Linear Model using Weibull Model. (Version: 2.16; Date: 2/28/2013)

The form of the probability function is: P[response] = background + (1-background)*[1-

EXP(-slope*dose)] 

Benchmark Dose Computation

BMR = 5% Extra risk

BMD = 1.34145

BMDL at the 95% confidence level = 0.89816

Parameter Estimates

Variable Estimate Default initial parameter values

Background 0 0.0833333

Slope 0.0382372 0.0404091

Power n/a 1

Analysis of Deviance Table

Model Log(likelihood) Number of

parameters

Deviance Test degrees of 

freedom

p-value

Full model −24.9756 6

Fitted model −27.0654 1 4.17949 5 0.5239

Reduced model −33.7401 1 17.529 5 0.003598
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-8 DRAFT―DO NOT CITE OR QUOTE

1 

2 

3 

4 

AIC: = 56.1307

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0 0 0 10 0

4 0.1418 1.418 0 10 −1.286

8 0.2635 2.635 2 10 −0.456

10 0.3178 3.178 3 10 −0.121

12 0.368 3.68 5 10 0.866

15 0.4365 4.365 5 10 0.405

5 

6

7 

Chi^2 = 2.79 d.f = 5 P-value = 0.7325
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-9 DRAFT―DO NOT CITE OR QUOTE

1 Table D-4. Model predictions for convulsions in female F344 rats exposed to 

2 RDX by gavage for 90 days (Crouse et al., 2006); BMR= 1% extra risk

Modela

Goodness of fit BMD1Pct

(mg/kg/d)

BMDL1Pct

p-value AIC (mg/kg/d) Basis for model selection

Gamma 0.923 55.085 3.10 0.355 The quantal-linear model had a 

BMD more than 10 times lower 

than the lowest dose, so this 

model was excluded from 

consideration. Of the remaining 

models, the multistage model 

was selected based on lowest 

BMDL (BMDLs differed by more 

than threefold). 

Logistic 0.733 56.607 1.60 0.681

LogLogistic 0.929 55.076 2.87 0.468

Probit 0.793 56.086 1.86 0.649

LogProbit 0.952 54.798 3.63 0.919

Weibull 0.892 55.420 2.30 0.259

Multistage 2° 0.954 53.595 1.69 0.236

Quantal-Linear 0.733 56.131 0.263 0.176

Multistage 3° 0.885 55.525 1.99 0.238

Multistage 4° 0.885 55.525 1.99 0.236

Multistage 5° 0.885 55.525 1.99 0.235

Dichotomous-Hill 0.964 56.265 4.77 0.778

3 

4 

5 

6 

7 

a

Selected model in bold; scaled residuals for selected model for doses 0, 4, 8, 10, 12, and 15 mg/kg-d were 0.00, 

−0.67, 0.14, 0.11, 0.64, and −0.51, respectively. The BMD10 and BMDL10 for the selected model were 5.98 and 

2.47, respectively. 

 0

 0.1

 0.2

 0.3

 0.4

 0.5

 0.6

 0.7

 0.8

 0 2 4 6 8 10 12 14

Fraction Affected

dose

Multistage Model, with BMR of 1% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the BM

14:06 02/27 2014

BMDL BMD

 

Multistage

8 

9 

10

11

Figure D-3. Plot of incidence rate by dose, with fitted curve for selected model, 

for convulsions in female F344 rats exposed to RDX by gavage for 90 days 

(Crouse et al., 2006). BMR= 1% extra risk; dose shown in mg/kg-day.
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-10 DRAFT―DO NOT CITE OR QUOTE

1 Multistage Model. (Version: 3.3; Date: 02/28/2013)

2

3 

4 

5 

6 

7 

8 

9 

10

11

12

13

14

15

16

17

18

The form of the probability function is: P[response] = background + (1-background)*[1-

EXP(-beta1*dose^1-beta2*dose^2...)]

Benchmark Dose Computation

BMR = 1% Extra risk

BMD = 1.98616

BMDL at the 95% confidence level = 0.235433

Parameter Estimates

Variable Estimate Default initial parameter values

Background 0 0

Beta(1) 0 0.0172961

Beta(2) 0.00234798 0.002476

Beta(3) 0.000100566 0

Beta(4) 0 0

Beta(5) 0 0

Analysis of Deviance Table

Model Log(likelihood)

Number of

parameters Deviance

Test degrees of 

freedom p-value

Full model −24.9756 6

Fitted model −25.7624 2 1.57351 4 0.8135

Reduced model −33.7401 1 17.529 5 0.003598

AIC: = 55.5247

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0 0 0 10 0

4 0.043 0.43 0 10 −0.671

8 0.1827 1.827 2 10 0.141

10 0.2849 2.849 3 10 0.106

12 0.4006 4.006 5 10 0.641

15 0.5801 5.801 5 10 −0.513

Chi^2 = 1.16 d.f = 4 P-value = 0.8854
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-11 DRAFT―DO NOT CITE OR QUOTE

1 Table D-5. Model predictions for convulsions in male F344 rats exposed to 

2 RDX by gavage for 90 days (Crouse et al., 2006); BMR = 10% extra risk

Modela

Goodness of fit BMD10Pct

(mg/kg-d)

BMDL10Pct

p-value AIC (mg/kg-d) Basis for model selection

Gamma 0.482 48.534 7.40 5.11 Of the models that provided an 

adequate fit, the multistage 3° 

model was selected based on 

lowest AIC. 

Logistic 0.335 49.692 7.18 5.03

LogLogistic 0.522 48.248 7.48 5.29

Probit 0.363 49.460 7.17 4.86

LogProbit 0.530 48.224 7.53 5.38

Weibull 0.376 49.496 6.84 4.47

Multistage 2° 0.307 50.335 4.54 2.95

Quantal-Linear 0.0553 56.530 1.98 1.38

Multistage 5°b

Multistage 4°

0.361 49.607 6.85 3.91

Multistage 3° 0.515 47.803 6.17 3.95

Dichotomous-Hill 0.701 48.408 8.34 6.32

3 

4 

5 

6 

7 

8 

a

Selected model in bold; scaled residuals for selected model for doses 0, 4, 8, 10, 12, and 15 mg/kg-d were 0.00, 

−0.54, −0.82, −0.40, 1.66, and −0.61, respectively. b

For the Multistage 5° model, the b4 coefficient estimates was 0 (boundary of parameters space). The models in 

this row reduced to the Multistage 4° model.
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-12 DRAFT―DO NOT CITE OR QUOTE

1 

2 

3 

4

5 

6 

7 

8 

9 

10

11

12

13

14

15

16

 0

 0.2

 0.4

 0.6

 0.8

 1

 0 2 4 6 8 10 12 14

Fraction Affected

dose

Multistage Model, with BMR of 10% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the BM

14:11 02/27 2014

BMDL BMD

 

Multistage

Figure D-4. Plot of incidence rate by dose, with fitted curve for selected model, 

for convulsions in male F344 rats exposed to RDX by gavage for 90 days 

(Crouse et al., 2006). BMR = 10% extra risk; dose shown in mg/kg-day.

Multistage Model. (Version: 3.3; Date: 02/28/2013)

The form of the probability function is: P[response] = background + (1-background)*[1-

EXP(-beta1*dose^1-beta2*dose^2...)]

Benchmark Dose Computation

BMR = 10% Extra risk

BMD = 6.17392

BMDL at the 95% confidence level = 3.94501

Parameter Estimates

Variable Estimate Default initial parameter values

Background 0 0

Beta(1) 0 0

Beta(2) 0 0.00691555

Beta(3) 0.000447707 0

17
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-13 DRAFT―DO NOT CITE OR QUOTE

1 Analysis of Deviance Table

2 

3

4 

5 

6 

7 

Model Log(likelihood)

Number of

parameters Deviance

Test degrees of 

freedom p-value

Full model −20.4721 6

Fitted model −22.9013 1 4.85838 5 0.4334

Reduced model −37.4599 1 33.9755 5 <0.0001

AIC: = 47.8027

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0 0 0 10 0

4 0.0282 0.282 0 10 −0.539

8 0.2049 2.049 1 10 −0.822

10 0.3609 3.609 3 10 −0.401

12 0.5387 5.387 8 10 1.658

15 0.7793 7.793 7 10 −0.605

Chi^2 = 4.24 d.f = 5 P-value = 0.5153
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-14 DRAFT―DO NOT CITE OR QUOTE

1 Table D-6. Model predictions for convulsions in male F344 rats exposed to 

2 RDX by gavage for 90 days (Crouse et al., 2006); BMR = 5% extra risk

Modela

Goodness of fit BMD5Pct

(mg/kg-d)

BMDL5Pct

p-value AIC (mg/kg-d) Basis for model selection

Gamma 0.482 48.534 6.47 3.96 Of the models that provided an 

adequate fit, the multistage 3° 

model was selected based on 

lowest AIC. 

Logistic 0.335 49.692 5.74 3.34

LogLogistic 0.522 48.248 6.51 4.14

Probit 0.363 49.460 5.92 3.26

LogProbit 0.530 48.224 6.71 4.40

Weibull 0.376 49.496 5.58 3.16

Multistage 2° 0.307 50.335 3.17 1.63

Quantal-Linear 0.0553 56.530 0.964 0.670

Multistage 5°b

Multistage 4°

0.361 49.607 5.56 1.99

Multistage 3° 0.515 47.803 4.86 2.19

Dichotomous-Hill 0.701 48.408 7.76 5.27

a

3 

4 

5 

6 

7 

8 

9 

Selected model in bold; scaled residuals for selected model for doses 0, 4, 8, 10, 12, and 15 mg/kg-d were 0.000, 

−0.54, −0.82, −0.40, 1.66, and −0.61, respectively. The BMD10 and BMDL10 for the selected model were 6.17 and 

3.95 mg/kg-d, respectively. b

For the Multistage 5° model, the beta coefficient estimates were 0 (boundary of parameters space). The models 

in this row reduced to the Multistage 4° model.
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-15 DRAFT―DO NOT CITE OR QUOTE

 0

 0.2

 0.4

 0.6

 0.8

 1

 0 2 4 6 8 10 12 14

Fraction Affected

dose

Multistage Model, with BMR of 5% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the BM

14:10 02/27 2014

BMDL BMD

 

Multistage

1 

2

3 

4 

5 

6 

7 

8 

9 

10

11

12

13

14

15

16

Figure D-5. Plot of incidence rate by dose, with fitted curve for selected model, 

for convulsions in male F344 rats exposed to RDX by gavage for 90 days 

(Crouse et al., 2006). BMR = 5% extra risk; dose shown in mg/kg-day.

Multistage Model. (Version: 3.3; Date: 02/28/2013)

The form of the probability function is: P[response] = background + (1-background)*[1-

EXP(-beta1*dose^1-beta2*dose^2...)]

Benchmark Dose Computation

BMR = 5% Extra risk

BMD = 4.85686

BMDL at the 95% confidence level = 2.19244

Parameter Estimates

Variable Estimate Default initial parameter values

Background 0 0 

Beta(1) 0 0 

Beta(2) 0 0.00691555

Beta(3) 0.000447707 0 

17
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-16 DRAFT―DO NOT CITE OR QUOTE

Analysis of Deviance Table

Model Log(likelihood)

Number of

parameters Deviance

Test degrees of 

freedom p-value

Full model −20.4721 6 

Fitted model −22.9013 1 4.85838 5 0.4334

Reduced model −37.4599 1 33.9755 5 <0.0001

1

 2 

3 

4 

5 

6 

7 

AIC: = 47.8027

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0 0 0 10 0 

4 0.0282 0.282 0 10 −0.539

8 0.2049 2.049 1 10 −0.822

10 0.3609 3.609 3 10 −0.401

12 0.5387 5.387 8 10 1.658

15 0.7793 7.793 7 10 −0.605

Chi^2 = 4.24 d.f = 5 P-value = 0.5153
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-17 DRAFT―DO NOT CITE OR QUOTE

Table D-7. Model predictions for convulsions in male F344 rats exposed to 

RDX by gavage for 90 days (Crouse et al., 2006); BMR = 1% extra risk

1 

2 

Modela

Goodness of fit BMD1Pct

(mg/kg/d)

BMDL1Pct

p-value AIC (mg/kg/d) Basis for model selection

Gamma 0.482 48.534 4.96 2.32 The multistage 2° model was 

selected based on lowest BMDL 

(BMDLs differed by more than 

threefold). 

Logistic 0.335 49.692 2.86 0.975

LogLogistic 0.522 48.248 4.79 2.38

Probit 0.363 49.460 3.60 1.01

LogProbit 0.530 48.224 5.41 3.00

Weibull 0.376 49.496 3.52 1.43

Multistage 2° 0.307 50.335 1.40 0.363

Quantal-Linear 0.0553 56.530 0.189 0.131

Multistage 5°b 0.361 49.607 3.42 0.392

Multistage 4°c 0.361 49.607 3.42 0.392

Multistage 3° 0.515 47.803 2.82 0.457

Dichotomous-Hill 0.701 48.408 6.64 3.47

3 

4 

5 

6 

7 

8 

9 

10

11

12

13

a

Selected model in bold; scaled residuals for selected model for doses 0, 4, 8, 10, 12, and 15 mg/kg-d were 0.00, 

−0.92, −1.26, −0.65, 1.76, and 0.11, respectively. The BMD10 and BMDL10 for the selected model were 4.54 and 

2.95 mg/kg-d, respectively. b

The Multistage 5° model may appear equivalent to the Multistage 4° model, however differences exist in digits 

not displayed in the table.

 0

 0.2

 0.4

 0.6

 0.8

 1

 0 2 4 6 8 10 12 14

Fraction Affected

dose

Multistage Model, with BMR of 1% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the BM

14:09 02/27 2014

BMDL BMD

 

Multistage

Figure D-6. Plot of incidence rate by dose, with fitted curve for selected model, 

for convulsions in male F344 rats exposed to RDX by gavage for 90 days 

(Crouse et al., 2006). BMR = 1% extra risk; dose shown in mg/kg-day.
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-18 DRAFT―DO NOT CITE OR QUOTE

Multistage Model. (Version: 3.3; Date: 02/28/2013)

The form of the probability function is: P[response] = background + (1-background)*[1-

EXP(-beta1*dose^1-beta2*dose^2...)]

Benchmark Dose Computation

BMR = 1% Extra risk

BMD = 1.40125

BMDL at the 95% confidence level = 0.363499

1 

2 

3 

4 

5 

6 

7 

8 

9 

10

11

12

13

14

16

17

18

15

19

Parameter Estimates

Variable Estimate Default initial parameter values

Background 0 0 

Beta(1) 0 0 

Beta(2) 0.00511858 0.00691555

Analysis of Deviance Table

Model Log(likelihood)

Number of

parameters Deviance

Test degrees of 

freedom p-value

Full model −20.4721 6 

Fitted model −24.1672 1 7.39017 5 0.1932

Reduced model −37.4599 1 33.9755 5 <0.0001

AIC: = 50.3345

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0 0 0 10 0 

4 0.0786 0.786 0 10 −0.924

8 0.2793 2.793 1 10 −1.264

10 0.4006 4.006 3 10 −0.649

12 0.5215 5.215 8 10 1.763

15 0.6839 6.839 7 10 0.11

Chi^2 = 5.99 d.f = 5 P-value = 0.3069
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-19 DRAFT―DO NOT CITE OR QUOTE

1 Table D-8. Model predictions for convulsions in male and female F344 rats 

2

3 

exposed to RDX by gavage for 90 days (Crouse et al., 2006); BMR = 10% extra 

risk

Modela

Goodness of fit BMD10Pct

(mg/kg-d)

BMDL10Pct

p-value AIC (mg/kg-d) Basis for model selection

Gamma 0.484 101.79 6.92 5.09 Of the models that provided an 

adequate fit, the multistage 3° 

model was selected based on 

lowest AIC. 

Logistic 0.231 104.55 6.86 5.34

LogLogistic 0.512 101.66 6.93 5.15

Probit 0.291 103.61 6.83 5.19

LogProbit 0.557 101.25 7.01 5.31

Weibull 0.369 102.91 6.52 4.62

Multistage 2° 0.364 103.03 4.97 3.75

Quantal-Linear 0.0369 111.56 2.32 1.77

Multistage 3° b

Multistage 4°

Multistage 5°

0.502 100.91 6.60 4.59

Dichotomous-Hill 0.696 101.64 7.73 5.98

4 

5 

6 

7 

8 

9 

a

Selected model in bold; scaled residuals for selected model for doses 0, 4, 8, 10, 12, and 15 mg/kg-d were 0.00, 

−0.69, −0.25, −0.06, 1.62, and −1.08, respectively. b

For the Multistage 4° and 5° models, the b4 and b5 coefficient estimates were 0 (boundary of parameters space). 

The models in this row reduced to the Multistage 3° model.
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-20 DRAFT―DO NOT CITE OR QUOTE

1 

2 

3

4 

5 

6 

7 

8 

9 

10

11

12

13

14

15

16

17

 0

 0.2

 0.4

 0.6

 0.8

 0 2 4 6 8 10 12 14

Fraction Affected

dose

Multistage Model, with BMR of 10% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the BM

14:05 02/27 2014

BMDL BMD

 

Multistage

Figure D-7. Plot of incidence rate by dose, with fitted curve for selected model, 

for convulsions in male and female F344 rats exposed to RDX by gavage for 

90 days (Crouse et al., 2006). BMR = 10% extra risk; dose shown in mg/kg-day.

Multistage Model. (Version: 3.3; Date: 02/28/2013)

The form of the probability function is: P[response] = background + (1-background)*[1-

EXP(-beta1*dose^1-beta2*dose^2...)]

Benchmark Dose Computation

BMR = 10% Extra risk

BMD = 6.60247

BMDL at the 95% confidence level = 4.59346

Parameter Estimates

Variable Estimate Default initial parameter values

Background 0 0

Beta(1) 0 0.00163806

Beta(2) 0 0.00485933

Beta(3) 0.000366065 0
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-21 DRAFT―DO NOT CITE OR QUOTE

1 Analysis of Deviance Table

3

4 

5 

7 

6 

2 

Model Log(likelihood)

Number of

parameters Deviance

Test degrees of 

freedom p-value

Full model −47.0806 6

Fitted model −49.4567 1 4.75213 5 0.4469

Reduced model −71.5289 1 48.8965 5 <0.0001

AIC: = 100.913

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0 0 0 20 0

4 0.0232 0.463 0 20 −0.689

8 0.1709 3.418 3 20 −0.248

10 0.3065 6.131 6 20 −0.063

12 0.4688 9.375 13 20 1.624

15 0.7093 14.186 12 20 −1.076

Chi^2 = 4.34 d.f = 5 P-value = 0.5021
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-22 DRAFT―DO NOT CITE OR QUOTE

1 Table D-9. Model predictions for convulsions in male and female F344 rats 

2

3 

exposed to RDX by gavage for 90 days (Crouse et al., 2006); BMR = 5% extra 

risk

Modela

Goodness of fit BMD5Pct

(mg/kg-d)

BMDL5Pct

p-value AIC (mg/kg-d) Basis for model selection

Gamma 0.484 101.79 5.78 3.80 Of the models that provided an 

adequate fit, the multistage 3° 

model was selected based on 

lowest AIC. 

Logistic 0.231 104.55 5.13 3.49

LogLogistic 0.512 101.66 5.74 3.85

Probit 0.291 103.61 5.29 3.43

LogProbit 0.557 101.25 6.01 4.20

Weibull 0.369 102.91 5.11 3.18

Multistage 2° 0.364 103.03 3.47 2.20

Quantal-Linear 0.0369 111.56 1.13 0.860

Multistage 3° 0.502 100.91 5.19 2.66

Multistage 4°

Multistage 5°b

0.502 100.91 5.19 2.65

Dichotomous-Hill 0.696 101.64 6.98 4.80

4 

5 

6 

7 

8 

9 

10 

a

Selected model in bold; scaled residuals for selected model for doses 0, 4, 8, 10, 12, and 15 mg/kg-d were 0.00, 

−0.69, −0.25, −0.06, 1.62, and −1.08, respectively. The BMD10 and BMDL10 for the selected model were 6.60 and 

4.59 mg/kg-d, respectively. b

For the Multistage 5° model, the b5 coefficient estimate was 0 (boundary of parameters space). The models in 

this row reduced to the Multistage 4° model.
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This document is a draft for review purposes only and does not constitute Agency policy.

D-23 DRAFT―DO NOT CITE OR QUOTE

1 

2 

3 

4 

5 

6 

7 

8 

9 

10

11

12

13

14

15

16

 0

 0.2

 0.4

 0.6

 0.8

 0 2 4 6 8 10 12 14

Fraction Affected

dose

Multistage Model, with BMR of 5% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the BM

14:04 02/27 2014

BMDL BMD

 

Multistage

Figure D-8. Plot of incidence rate by dose, with the fitted curve of the selected 

model, for convulsions in male and female F344 rats exposed to RDX by 

gavage for 90 days (Crouse et al., 2006). BMR = 5% extra risk; dose shown in 

mg/kg-day.

Multistage Model. (Version: 3.3; Date: 02/28/2013)

The form of the probability function is: P[response] = background + 

(1-background)*[1-EXP(-beta1*dose^1-beta2*dose^2...)]

Benchmark Dose Computation

BMR = 5% Extra risk

BMD = 5.19399

BMDL at the 95% confidence level = 2.65815

Parameter Estimates

Variable Estimate Default initial parameter values

Background 0 0

Beta(1) 0 0.00163806

Beta(2) 0 0.00485933

Beta(3) 0.000366065 0

17
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This document is a draft for review purposes only and does not constitute Agency policy.

D-24 DRAFT―DO NOT CITE OR QUOTE

1 Analysis of Deviance Table

2 

3

4 

5 

6 

7 

8 

Model Log(likelihood)

Number of

parameters Deviance

Test degrees of 

freedom p-value

Full model −47.0806 6

Fitted model −49.4567 1 4.75213 5 0.4469

Reduced model −71.5289 1 48.8965 5 <0.0001

AIC: = 100.913

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0 0 0 20 0

4 0.0232 0.463 0 20 −0.689

8 0.1709 3.418 3 20 −0.248

10 0.3065 6.131 6 20 −0.063

12 0.4688 9.375 13 20 1.624

15 0.7093 14.186 12 20 −1.076

Chi^2 = 4.34 d.f = 5 P-value = 0.5021
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This document is a draft for review purposes only and does not constitute Agency policy.

D-25 DRAFT―DO NOT CITE OR QUOTE

11

12

13

14

15

16

1 Table D-10. Model predictions for convulsions in male and female F344 rats 

2 

3

exposed to RDX by gavage for 90 days (Crouse et al., 2006); BMR = 1% extra 

risk

Modela

Goodness of fit BMD1Pct

(mg/kg/d)

BMDL1Pct

p-value AIC (mg/kg/d) Basis for model selection

Gamma 0.484 101.79 4.02 2.03 The quantal-linear model did not 

fit the data adequately (p-value <

0.10), so it was excluded from 

consideration. Of the remaining 

models, the multistage 2° model 

was selected based on lowest 

BMDL (BMDLs differed by more 

than threefold). 

Logistic 0.231 104.55 2.04 0.987

LogLogistic 0.512 101.66 3.79 2.00

Probit 0.291 103.61 2.57 1.03

LogProbit 0.557 101.25 4.50 2.69

Weibull 0.369 102.91 2.94 1.35

Multistage 2° 0.364 103.03 1.53 0.544

Quantal-Linear 0.0369 111.56 0.222 0.169

Multistage 5°b

Multistage 4°

0.502 100.91 3.02 0.549

Multistage 3° 0.502 100.91 3.02 0.569

Dichotomous-Hill 0.696 101.64 5.62 2.90

4 

5 

6 

7 

8 

9 

10

a

Selected model in bold; scaled residuals for selected model for doses 0, 4, 8, 10, 12, and 15 mg/kg-d were 0.00, 

−1.19, −0.93, −0.45, 1.71, and −0.16, respectively. The BMD10 and BMDL10 for the selected model were 4.97 and 

3.75 mg/kg-d, respectively. b

For the Multistage 5° model, the beta coefficient estimates were 0 (boundary of parameters space). The models 

in this row reduced to the Multistage 4° model.

 0

 0.2

 0.4

 0.6

 0.8

 0 2 4 6 8 10 12 14

Fraction Affected

dose

Multistage Model, with BMR of 1% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the BM

14:03 02/27 2014

BMDL BMD

 

Multistage

Figure D-9. Plot of incidence rate by dose, with the fitted curve of the selected 

model, for convulsions in male and female F344 rats exposed to RDX by 

gavage for 90 days (Crouse et al., 2006). BMR = 1% extra risk; dose shown in 

mg/kg-day.
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-26 DRAFT―DO NOT CITE OR QUOTE

1 Multistage Model. (Version: 3.3; Date: 02/28/2013)

2

3 

4 

5 

6 

7 

8 

 9 

The form of the probability function is: P[response] = background + (1-background)*[1-

EXP(-beta1*dose^1-beta2*dose^2...)]

Benchmark Dose Computation

BMR = 1% Extra risk

BMD = 1.53434

BMDL at the 95% confidence level = 0.544329

10 Parameter Estimates

11

12

13

14

16

17

18

15 

19

Variable Estimate Default initial parameter values

Background 0 0

Beta(1) 0 0.00163806

Beta(2) 0.00426912 0.00485933

Analysis of Deviance Table

Model Log(likelihood)

Number of

parameters Deviance

Test degrees of 

freedom p-value

Full model −47.0806 6

Fitted model −50.5158 1 6.87034 5 0.2305

Reduced model −71.5289 1 48.8965 5 <0.0001

AIC: = 103.032

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0 0 0 20 0

4 0.066 1.321 0 20 −1.189

8 0.2391 4.782 3 20 −0.934

10 0.3475 6.95 6 20 −0.446

12 0.4592 9.185 13 20 1.712

15 0.6173 12.346 12 20 −0.159

Chi^2 = 5.44 d.f = 5 P-value = 0.3644
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This document is a draft for review purposes only and does not constitute Agency policy.

D-27 DRAFT―DO NOT CITE OR QUOTE

1 Table D-11. Model predictions for convulsions in female F344 rats exposed to

2 RDX by gavage on gestation days 6−19 (Cholakis, 1980); BMR = 10% extra risk

Modela

Goodness of fit BMD10Pct

(mg/kg-d)

BMDL10Pct

p-value AIC (mg/kg-d) Basis for model selection

Gamma 0.989 42.003 3.62 1.56 The quantal-linear model is 

selected based on lowest BMDL 

(BMDLs differed by more than 

threefold). 

Logistic 0.526 43.556 8.92 6.14

LogLogistic 0.991 41.996 3.45 1.53

Probit 0.577 43.348 7.64 5.39

LogProbit 1.000 41.963 3.13 1.51

Weibull 0.983 42.026 3.81 1.55

Multistage 3°b 0.960 42.113 4.26 1.54

Multistage 2° 0.960 42.113 4.26 1.54

Quantal-Linear 0.669 42.077 1.88 1.29

3 

4 

5 

6 

7 

8 

9 

10

11

12

13

a

Selected model in bold; scaled residuals for selected model for doses 0, 0.2, 2, and 20 mg/kg-d were 0.00, −0.52, 

−1.03, and 0.49, respectively. b

The Multistage 3° model may appear equivalent to the Multistage 2° model, however differences exist in digits 

not displayed in the table.

 0

 0.2

 0.4

 0.6

 0.8

 0 5 10 15 20

Fraction Affected

dose

Quantal Linear Model, with BMR of 10% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the 

09:29 06/06 2014

BMDL BMD

 

Quantal Linear

Figure D-10. Plot of incidence rate by dose, with the fitted curve of the 

selected model, for convulsions in female F344 rats exposed to RDX by gavage 

on gestation days 6−19 (Cholakis, 1980). BMR = 10% extra risk; dose shown in 

mg/kg-day. 
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-28 DRAFT―DO NOT CITE OR QUOTE

Quantal Linear Model using Weibull Model (Version: 2.16; Date: 2/28/2013)

The form of the probability function is: P[response] = background + (1-background)*[1-

EXP(-slope*dose)] 

Benchmark Dose Computation

BMR = 10% Extra risk

BMD = 1.87886

BMDL at the 95% confidence level = 1.28909

1 

2 

3 

4 

5 

6 

7 

8 

9 

10

11

12

13

14

15

16

17

18

19

Parameter Estimates

Variable Estimate Default initial parameter values

Background 0 0.0384615

Slope 0.056077 0.0588587

Power n/a 1 

Analysis of Deviance Table

Model Log(likelihood)

Number of

parameters Deviance

Test degrees of 

freedom p-value

Full model −18.9808 4 

Fitted model −20.0384 1 2.11537 3 0.5488

Reduced model −47.9793 1 57.9972 3 <0.0001

AIC: = 42.0769

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0 0 0 24 0 

0.2 0.0112 0.268 0 24 −0.52

2 0.1061 2.546 1 24 −1.025

20 0.6742 16.856 18 25 0.488

Chi^2 = 1.56 d.f = 3 P-value = 0.6686
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-29 DRAFT―DO NOT CITE OR QUOTE

1 Table D-12. Model predictions for convulsions in female F344 rats exposed to 

2 RDX by gavage on gestation days 6−19 (Cholakis, 1980); BMR = 5% extra risk

Modela

Goodness of fit BMD5Pct

(mg/kg-d)

BMDL5Pct

p-value AIC (mg/kg-d) Basis for model selection

Gamma 0.989 42.003 2.31 0.759 The quantal-linear model is 

selected based on lowest BMDL 

(BMDLs differed by more than 

threefold). 

Logistic 0.526 43.556 6.53 3.90

LogLogistic 0.991 41.996 2.27 0.823

Probit 0.577 43.348 5.41 3.34

LogProbit 1.000 41.963 2.18 0.902

Weibull 0.983 42.026 2.36 0.756

Multistage 2° 0.960 42.113 2.51 0.747

Quantal-Linear 0.669 42.077 0.915 0.628

Multistage 3°b 0.960 42.113 2.51 0.747

3 

4 

5 

6 

7 

8 

9 

10

11

12

13

14

a

Selected model in bold; scaled residuals for selected model for doses 0, 0.2, 2, and 20 mg/kg-d were 0.00, −0.52, 

−1.03, and 0.49, respectively. The BMD10 and BMDL10 for the selected model were 1.88 and 1.29 mg/kg-d, 

respectively. 

b

The Multistage 3° model may appear equivalent to the Multistage 2° model, however differences exist in digits 

not displayed in the table.

 0

 0.2

 0.4

 0.6

 0.8

 0 5 10 15 20

Fraction Affected

dose

Quantal Linear Model, with BMR of 5% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the B

15:24 05/23 2014

BMDL BMD

 

Quantal Linear

Figure D-11. Plot of incidence rate by dose, with the fitted curve of the 

selected model, for convulsions in female F344 rats exposed to RDX by gavage 

on gestation days 6−19 (Cholakis, 1980). BMR = 5% extra risk; dose shown in 

mg/kg-day. 
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-30 DRAFT―DO NOT CITE OR QUOTE

 1 

2

3 

4 

5 

6 

7 

8 

9 

10

11

12

13

14

15

16

17

18

19

20

Quantal Linear Model using Weibull Model (Version: 2.16; Date: 2/28/2013)

The form of the probability function is: P[response] = background + (1-background)*[1-

EXP(-slope*dose)] 

Benchmark Dose Computation

BMR = 5% Extra risk

BMD = 0.914694

BMDL at the 95% confidence level = 0.627577

Parameter Estimates

Variable Estimate Default initial parameter values

Background 0 0.0384615

Slope 0.056077 0.0588587

Power n/a 1

Analysis of Deviance Table

Model Log(likelihood)

Number of

parameters Deviance

Test degrees of 

freedom p-value

Full model −18.9808 4

Fitted model −20.0384 1 2.11537 3 0.5488

Reduced model −47.9793 1 57.9972 3 <0.0001

AIC: = 42.0769

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0 0 0 24 0

0.2 0.0112 0.268 0 24 −0.52

2 0.1061 2.546 1 24 −1.025

20 0.6742 16.856 18 25 0.488

Chi^2 = 1.56 d.f = 3 P-value = 0.6686
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This document is a draft for review purposes only and does not constitute Agency policy.

D-31 DRAFT―DO NOT CITE OR QUOTE

1 Table D-13. Model predictions for convulsions in female F344 rats exposed to 

2 RDX by gavage on gestation days 6−19 (Cholakis, 1980); BMR = 1% extra risk

Modela

Goodness of fit BMD1Pct

(mg/kg-d)

BMDL1Pct

p-value AIC (mg/kg-d) Basis for model selection

Gamma 0.989 42.003 0.866 0.149 The quantal-linear model is 

selected based on lowest AIC. 

Logistic 0.526 43.556 2.46 1.05

LogLogistic 0.991 41.996 0.902 0.201

Probit 0.577 43.348 1.96 0.871

LogProbit 1.000 41.963 1.11 0.335

Weibull 0.983 42.026 0.798 0.148

Multistage 3°b 0.960 42.113 0.638 0.146

Multistage 2°c 0.960 42.113 0.638 0.146

Quantal-Linear 0.669 42.077 0.179 0.123

3 

4 

5 

6 

7 

8 

9 

a

Selected model in bold; scaled residuals for selected model for doses 0, 0.2, 2, and 20 mg/kg-d were 0.00, −0.52, 

−1.03, and 0.49, respectively. The BMD10 and BMDL10 for the selected model were 1.88 and 1.29 mg/kg-d, 

respectively. 

b

The Multistage 3° model may appear equivalent to the Multistage 2° model, however differences exist in digits 

not displayed in the table.

10

11

12

13

14

15

16 

 0

 0.2

 0.4

 0.6

 0.8

 0 5 10 15 20

Fraction Affected

dose

Quantal Linear Model, with BMR of 1% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the B

14:19 07/28 2014

BMDLBMD

 

Quantal Linear

Figure D-12. Plot of incidence rate by dose, with the fitted curve of the 

selected model, for convulsions in female F344 rats exposed to RDX by gavage 

on gestation days 6−19 (Cholakis, 1980). BMR = 1% extra risk; dose shown in 

mg/kg-day.
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This document is a draft for review purposes only and does not constitute Agency policy.

D-32 DRAFT―DO NOT CITE OR QUOTE

1 Quantal Linear Model using Weibull Model (Version: 2.16; Date: 2/28/2013)

2

3 

4 

5 

6 

7 

8 

9 

10

11

12

13

14

15

16

17

18

1

2

9

0

The form of the probability function is: P[response] = background + (1-background)*[1-

EXP(-slope*dose)] 

Benchmark Dose Computation

BMR = 1% Extra risk

BMD = 0.179224

BMDL at the 95% confidence level = 0.122966

Parameter Estimates

Variable Estimate Default initial parameter values

Background 0 0.0384615

Slope 0.056077 0.0588587

Power n/a 1

Analysis of Deviance Table

Model Log(likelihood)

Number of

parameters Deviance

Test degrees of 

freedom p-value

Full model −18.9808 4

Fitted model −20.0384 1 2.11537 3 0.5488

Reduced model −47.9793 1 57.9972 3 <0.0001

AIC: = 42.0769

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0 0 0 24 0

0.2 0.0112 0.268 0 24 −0.52

2 0.1061 2.546 1 24 −1.025

20 0.6742 16.856 18 25 0.488

Chi^2 = 1.56 d.f = 3 P-value = 0.6686
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-33 DRAFT―DO NOT CITE OR QUOTE

1 Male Reproductive Effects

2

3 

4 

5 

6 

7 

8 

9 

10

11

12

13

14

15

Table D-14 presents the BMD model results for incidence of testicular degeneration for 

male B6C3F1 mice based on data from Lish et al. (1984), using a BMR of 10% extra risk.

Table D-14. Model predictions for testicular degeneration in male B6C3F1

mice exposed to RDX by diet for 24 months (Lish et al., 1984); BMR = 10% 

extra risk

Model

a

Goodness of fit BMD10Pct

(mg/kg-d)

BMDL10Pct

p-value AIC (mg/kg-d) Basis for model selection

Gammab

Weibull

Quantal-Linear

0.357 101.10 66.5 35.4 The log-probit model was 

selected based on lowest BMDL 

(BMDLs differed by more than 

threefold). Logistic 0.159 103.40 97.1 66.1

LogLogistic 0.377 100.91 63.6 32.3

Probit 0.178 103.12 93.1 61.4

LogProbit 0.876 97.564 56.0 16.3

Multistage 2°c

Multistage 3°

Multistage 4°

0.357 101.10 66.5 35.4

a

Selected model in bold; scaled residuals for selected model for doses 0, 1.5, 7, 35, and 107 mg/kg-d were 0.00, 

0.32, −0.61, 0.43, and −0.17, respectively. b

For the Gamma and Weibull models, the power parameter estimates were 1 (boundary of parameter space). The 

models in this row are equivalent to the Quantal-Linear model. c

The Multistage 3° and 4° model had b3 and b4 coefficient estimates of 0 (boundary of parameters space). The 

models in this row reduced to the Multistage 2° model. The models in this row may appear equivalent to the 

Gamma model, however differences exist in digits not displayed in the table.
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-34 DRAFT―DO NOT CITE OR QUOTE

1 

2 

3

4 

5 

6 

7 

8 

9 

10

11

12

13

14

15

16

17

18

19

 0

 0.05

 0.1

 0.15

 0.2

 0.25

 0.3

 0 20 40 60 80 100

Fraction Affected

dose

LogProbit Model, with BMR of 10% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the B

13:42 02/14 2014

BMDL BMD

 

LogProbit

Figure D-13. Plot of incidence rate by dose, with fitted curve for selected 

model, for testicular degeneration in male B6C3F1 mice exposed to RDX by 

diet for 24 months (Lish et al., 1984). BMR = 10% extra risk; dose shown in 

mg/kg-day.

Probit Model. (Version: 3.3; Date: 2/28/2013)

The form of the probability function is: P[response] = Background + (1-Background) * 

CumNorm(Intercept+Slope*Log(Dose)),where CumNorm(.) is the cumulative normal 

distribution function

Slope parameter is not restricted

Benchmark Dose Computation

BMR = 10% Extra risk

BMD = 55.9784

BMDL at the 95% confidence level = 16.2787

Parameter Estimates

Variable Estimate Default initial parameter values

background 0 0

intercept −2.0054E+00 −1.9976E+00

slope 0.179828 0.172286

20
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-35 DRAFT―DO NOT CITE OR QUOTE

1 Analysis of Deviance Table

2 

3 

4 

5 

6 

7 

Model Log(likelihood)

Number of

parameters Deviance

Test degrees of 

freedom p-value

Full model −46.4212 5 

Fitted model −46.7817 2 0.721088 3 0.8682

Reduced model −52.1663 1 11.4902 4 0.02157

AIC: = 97.5635

Goodness of Fit Table

Scaled 

Dose Est. prob. Expected Observed Size residuals

0 0 0 0 63 0 

1.5 0.0267 1.599 2 60 0.321

7 0.0489 3.033 2 62 −0.608

35 0.086 5.072 6 59 0.431

107 0.122 3.294 3 27 −0.173

Chi^2 = 0.69 d.f = 3 P-value = 0.8759
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This document is a draft for review purposes only and does not constitute Agency policy.

D-36 DRAFT―DO NOT CITE OR QUOTE

1 Kidney Effects

2 

3

4 

5 

6 

7 

8 

9 

10

11

12

13

14

15

16

Table D-15 presents the BMD model results for incidence of suppurative inflammation of 

the prostate in male F344 rats based on data from Levine et al. (1983), using a BMR of 10% extra 

risk.

Table D-15. Model predictions for prostate suppurative inflammation in male 

F344 rats exposed to RDX by diet for 24 months (Levine et al., 1983); 

BMR = 10% extra risk

Modela

Goodness of fit BMD10Pct

(mg/kg/d)

BMDL10Pct

p-value AIC (mg/kg/d) Basis for model selection

Gammab

Multistage 2°

Quantal-Linear

Multistage 3°

Multistage 4°

0.288 200.37 4.61 3.24 The log-probit model is selected 

based on lowest BMDL (BMDLs 

differ by more than threefold). 

Logistic 0.102 203.50 10.8 8.58

LogLogistic 0.328 200.05 3.33 2.09

Probit 0.116 203.10 9.91 7.96

LogProbit 0.204 202.03 1.67 0.469

Weibullg 0.288 200.37 4.61 3.24

a

Selected model in bold; scaled residuals for selected model for doses 0, 0.3, 1.5, 8, and 40 mg/kg-d were −0.289, 

0.172, 0.846, −1.298, and 0.819, respectively. b

The Gamma model had a power parameter estimate was 1 (boundary of parameter space). The multistage 2, 3, 

and 4 models had b2, b3, and b4 coefficients of 0 (boundary of parameter space). The models in this row are 

equivalent to the Quantal-Linear model. c

The Weibull model may appear equivalent to the quantal-linear model, however differences exist in digits not 

displayed in the table.
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-37 DRAFT―DO NOT CITE OR QUOTE

1 

2 

3

4 

5 

6 

7 

8 

9 

10

11

12

13

14

15

16

17

18

19

20

 0

 0.1

 0.2

 0.3

 0.4

 0.5

 0.6

 0.7

 0.8

 0 5 10 15 20 25 30 35 40

Fraction Affected

dose

LogProbit Model, with BMR of 10% Extra Risk for the BMD and 0.95 Lower Confidence Limit for the BM

13:39 02/14 2014

BMDL BMD

 

LogProbit

Figure D-14. Plot of incidence rate by dose, with fitted curve for selected 

model, for prostate suppurative inflammation in male F344 rats exposed to 

RDX by diet for 24 months (Levine et al., 1983). BMR = 10% extra risk; dose 

shown in mg/kg/day.

Probit Model. (Version: 3.3; Date: 2/28/2013)

The form of the probability function is: P[response] = Background + (1-Background) * 

CumNorm(Intercept+Slope*Log(Dose)),where CumNorm(.) is the cumulative normal 

distribution function

Slope parameter is not restricted

Benchmark Dose Computation

BMR = 10% Extra risk

BMD = 1.67454

BMDL at the 95% confidence level = 0.468688

Parameter Estimates

Variable Estimate Default initial parameter values

background 0.0452202 0.037037

intercept −1.4970E+00 −1.3564E+00

slope 0.417872 0.36341
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-38 DRAFT―DO NOT CITE OR QUOTE

1 Analysis of Deviance Table

2

3 

4 

5 

6 

7 

8 

Model Log(likelihood)

Number of

parameters Deviance

Test degrees of 

freedom p-value

Full model −96.3905 5

Fitted model −98.0147 3 3.24837 2 0.1971

Reduced model −118.737 1 44.6933 4 <0.0001

AIC: = 202.029

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0.0452 2.442 2 54 −0.289

0.3 0.0669 3.682 4 55 0.172

1.5 0.1332 6.927 9 52 0.846

8 0.2982 16.402 12 55 −1.298

40 0.5396 16.726 19 31 0.819

Chi^2 = 3.18 d.f = 2 P-value = 0.2035
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1 D.2. BENCHMARK DOSE MODELING SUMMARY FOR CANCER ENDPOINTS

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The cancer endpoints that were selected for dose-response modeling are presented in Table 

D-16. For each endpoint, the doses and tumor incidence data used for the modeling are presented.

Table D-16. Cancer endpoints selected for dose-response modeling for RDX

Endpoint and reference Species/sex Dose (mg/kg-d) Incidence/total

Hepatocellular adenomas or 

carcinomas

Parker et al. (2006)

Female B6C3F1

mice

0

1.5

7 

35

107

1/67 (1%)

4/62 (6%)

5/63 (8%)

10 /64 (16%)

4/31 (13%)

Alveloar/bronchiolar adenomas or 

carcinomas

Lish et al. (1984)

Female B6C3F1

mice

0

1.5

7 

35

107

7/65 (11%)

3/62 (5%)

8/64 (13%)

12/64 (19%)

7/31 (23%)

Hepatocellular adenomas or 

carcinomas

Levine et al. (1983)

Male F344 rats 0

0.3

1.5

8 

40

1/55 (2%)

0/55 (0%)

0/52 (0%)

2/55 (4%)

2/31a (6%)

a

The denominators listed in the table represent the number of animals that were alive one year after dosing 

began.

D.2.1. Evaluation of Model Fit and Model Selection

For each endpoint, BMDS multistage-cancer models5 were fitted to the data using the 

maximum likelihood method. Each model was tested for goodness-of-fit using a chi-square 

goodness-of-fit test (χ2 p-value < 0.056 indicates lack of fit). Other factors were used to assess 

model fit, such as scaled residuals, visual fit, and adequacy of fit in the low-dose region and in the 

vicinity of the BMR.

For each endpoint, the BMDL estimate (95% lower confidence limit on the BMD, as 

estimated by the profile likelihood method) and AIC value were used to select a best-fit model from 

among the models exhibiting adequate fit. If the BMDL estimates were “sufficiently close,” that is, 

differed by more than threefold, the model selected was the one that yielded the lowest AIC value. 

If the BMDL estimates were not sufficiently close, the lowest BMDL was selected as the POD. 

After selecting models for the two endpoints, the results were combined using MS-COMBO 

in BMDS. This procedure analyzes the incidence of a tumor (adenoma or carcinoma) defined as 

 

5The coefficients of the multistage-cancer models were restricted to be nonnegative (beta’s ≥ 0). 6A significance level of 0.05 is used for selecting cancer models because the model family (multistage) is 

selected a priori (Benchmark Dose Technical Guidance Document, U.S. EPA, 2012).
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1 present if either the hepatocellular or alveolar/bronchiolar tumor (or both) was present, and not 

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present otherwise. The two endpoints were assumed to be independent.

D.2.2. Modeling Results

Details of the BMD modeling for mouse tumor data sets are provided in Tables D-17 to D-20 

below. In addition, this appendix presents a quantitative dose-response analysis using rat liver 

tumor data and detailed BMD modeling results (see Table D-22). The analysis of rat liver tumor 

data and resulting candidate OSF is presented for comparison with other OSF estimates provided in 

Section 2.3.3 of the Toxicological Review. 

Mouse Tumor Data – BMD Modeling Documentation

Table D-17. Model predictions for combined alveolar/bronchiolar adenoma 

and carcinoma in female B6C3F1 mice exposed to RDX by diet for 24 months 

(Lish et al., 1984); BMR = 10% extra risk

Modela

Goodness of fit BMD10Pct 

(mg/kg-d)

BMDL10Pct 

p-value AIC (mg/kg-d) Basis for model selection

Multistage 1°b

Multistage 2°

Multistage 3°

Multistage 4°

0.417 218.68 52.8 27.7 All the models reduced to the 

multistage 1° model, so it was 

selected. 

a

Selected model in bold. Scaled residuals for the selected model for doses 0, 1.5, 7, 35, and 107 mg/kg-d were 

0.40, −1.27, 0.50, 0.73, and −0.52, respectively. b

For the multistage 2°, 3°, and 4° models, the b2, b3 and b4 coefficient estimates were 0 (boundary of parameter 

space). The models in this row reduced to the multistage 1° model.
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 1 

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 0

 0.05

 0.1

 0.15

 0.2

 0.25

 0.3

 0.35

 0.4

 0.45

 0 20 40 60 80 100

Fraction Affected

dose

Multistage Cancer Model, with BMR of 10% Extra Risk for the BMD and 0.95 Lower Confidence Limit for t 

16:09 02/14 2014

BMDL BMD

 

Multistage Cancer

Linear extrapolation

Figure D-15. Plot of incidence rate by dose, with the fitted curve for the 

selected model, for combined alveolar/bronchiolar adenoma and carcinoma 

in female B6C3F1 mice exposed to RDX by diet for 24 months (Lish et al., 

1984). BMR = 10% extra risk; dose shown in mg/kg-day.

Multistage Cancer Model. (Version: 1.10; Date: 02/28/2013)

The form of the probability function is: P[response] = background + (1-background)*[1-

EXP(-beta1*dose^1-beta2*dose^2...)]

The parameter betas are restricted to be positive

Benchmark Dose Computation

BMR = 10% Extra risk

BMD = 52.8078

BMDL at the 95% confidence level = 27.748

BMDU at the 95% confidence level = 194.806

Taken together, (27.748, 194.806) is a 90% two-sided confidence interval for the BMD

Multistage Cancer Slope Factor = 0.00360387

Parameter Estimates

Variable Estimate Default initial parameter values

Background 0.093168 0.0998927

Beta(1) 0.00199517 0.00155773
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1 

2

3 

4 

5 

6 

7 

8 

9 

Analysis of Deviance Table

Model Log(likelihood)

Number of

parameters Deviance

Test degrees of 

freedom p-value

Full model −105.777 5

Fitted model −107.341 2 3.12764 3 0.3724

Reduced model −110.164 1 8.77367 4 0.06701

AIC: = 218.682

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0.0932 6.056 7 65 0.403

1.5 0.0959 5.944 3 62 −1.27

7 0.1057 6.768 8 64 0.501

35 0.1543 9.877 12 64 0.734

107 0.2675 8.292 7 31 −0.524

Chi^2 = 2.84 d.f = 3 P-value = 0.4168
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1 Table D-18. Model predictions for combined alveolar/bronchiolar adenoma 

2 

3

and carcinoma in female B6C3F1 mice exposed to RDX by diet for 24 months 

(Lish et al., 1984); BMR = 5% extra risk

Modela

Goodness of fit BMD5Pct

(mg/kg-d)

BMDL5Pct

p-value AIC (mg/kg-d) Basis for model selection

Multistage 1°b

Multistage 2°

Multistage 3°

Multistage 4°

0.417 218.68 25.7 13.5 All the models reduced to the 

multistage 1° model, so it was 

selected.

4 

5 

6 

7 

8 

a

Selected model in bold. Scaled residuals for the selected model for doses 0, 1.5, 7, 35, and 107 mg/kg-d were 

0.40, −0.40, −1.27, 0.50, 0.73, and −0.52, respectively. The BMD10 and BMDL10 for the selected model were 52.8 

and 27.7 mg/kg-d, respectively.

9 

10

11

12

13

14

15

 0

 0.05

 0.1

 0.15

 0.2

 0.25

 0.3

 0.35

 0.4

 0.45

 0 20 40 60 80 100

Fraction Affected

dose

Multistage Cancer Model, with BMR of 5% Extra Risk for the BMD and 0.95 Lower Confidence Limit for th 

16:11 02/14 2014

BMDL BMD

 

Multistage Cancer

Linear extrapolation

Figure D-16. Plot of incidence rate by dose, with fitted curve for selected 

model, for combined alveolar/bronchiolar adenoma and carcinoma in female 

B6C3F1 mice exposed to RDX by diet for 24 months (Lish et al., 1984). 

BMR = 5% extra risk; dose shown in mg/kg-day.
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1 Multistage Cancer Model. (Version: 1.10; Date: 02/28/2013)

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The form of the probability function is: P[response] = background + (1-background)*[1-

EXP(-beta1*dose^1-beta2*dose^2...)]

The parameter betas are restricted to be positive

Benchmark Dose Computation

BMR = 5% Extra risk

BMD = 25.7088

BMDL at the 95% confidence level = 13.5087

BMDU at the 95% confidence level = 94.8384

Taken together, (13.5087, 94.8384) is a 90% two-sided confidence interval for the BMD

Multistage Cancer Slope Factor = 0.00370131

Parameter Estimates

Variable Estimate Default initial parameter values

Background 0.093168 0.0998927

Beta(1) 0.00199517 0.00155773

Analysis of Deviance Table

Model Log(likelihood)

Number of

parameters Deviance

Test degrees of 

freedom p-value

Full model −105.777 5

Fitted model −107.341 2 3.12764 3 0.3724

Reduced model −110.164 1 8.77367 4 0.06701

AIC: = 218.682

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0.0932 6.056 7 65 0.403

1.5 0.0959 5.944 3 62 −1.27

7 0.1057 6.768 8 64 0.501

35 0.1543 9.877 12 64 0.734

107 0.2675 8.292 7 31 −0.524

Chi^2 = 2.84 d.f = 3 P-value = 0.4168
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1 Table D-19. Model predictions for combined hepatocellular adenoma and 

2 

3

carcinoma in female B6C3F1 mice exposed to RDX by diet for 24 months 

(Parker et al., 2006); BMR = 10% extra risk

Modela

Goodness of fit BMD10Pct

(mg/kg-d)

BMDL10Pct

p-value AIC (mg/kg-d) Basis for model selection

Multistage 1°b

Multistage 2°

Multistage 3°

Multistage 4°

0.160 164.06 64.2 32.6 All the models reduced to the 

multistage 1° model, so it was selected.

4 

5 

6 

7 

8 

9 

a

Selected model in bold. Scaled residuals for the selected model for doses 0, 1.5, 7, 35, and 107 mg/kg-d were 

−1.37, 0.35, 0.54, 1.34, and −1.05, respectively. b

For the multistage 2°, 3°, and 4° models, the b2, b3 and b4 coefficient estimates were 0 (boundary of parameter 

space). The models in this row reduced to the multistage 1° model. 

 0

 0.05

 0.1

 0.15

 0.2

 0.25

 0.3

 0 20 40 60 80 100

Fraction Affected

dose

Multistage Cancer Model, with BMR of 10% Extra Risk for the BMD and 0.95 Lower Confidence Limit for t 

16:21 02/14 2014

BMDL BMD

 

Multistage Cancer

Linear extrapolation

10

11

12

13

14

15

Figure D-17. Plot of incidence rate by dose, with fitted curve for selected 

model, for combined hepatocellular adenoma and carcinoma in female B6C3F1

mice exposed to RDX by diet for 24 months (Parker et al., 2006). BMR = 10% 

extra risk; dose shown in mg/kg-day.
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1 Multistage Cancer Model. (Version: 1.10; Date: 02/28/2013)

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The form of the probability function is: P[response] = background + (1-background)*[1-

EXP(-beta1*dose^1-beta2*dose^2...)]

The parameter betas are restricted to be positive

Benchmark Dose Computation

BMR = 10% Extra risk

BMD = 64.203

BMDL at the 95% confidence level = 32.6282

BMDU at the 95% confidence level = 281.385

Taken together, (32.6282, 281.385) is a 90% two-sided confidence interval for the BMD

Multistage Cancer Slope Factor = 0.00306483

Parameter Estimates

Variable Estimate Default initial parameter values

Background 0.0520755 0.0658334

Beta(1) 0.00164105 0.000876864

Analysis of Deviance Table

Model Log(likelihood)

Number of

parameters Deviance

Test degrees of 

freedom p-value

Full model −77.1516 5

Fitted model −80.0315 2 5.75967 3 0.1239

Reduced model −82.5216 1 10.74 4 0.02965

AIC: = 164.063

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0.0521 3.489 1 67 −1.369

1.5 0.0544 3.373 4 62 0.351

7 0.0629 3.963 5 63 0.538

35 0.105 6.719 10 64 1.338

107 0.2047 6.347 4 31 −1.045

Chi^2 = 5.17 d.f = 3 P-value = 0.16
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1 Table D-20. Model predictions for B6C3F1 female mouse combined 

2 

3

hepatocellular adenoma and carcinoma in mice exposed to RDX by diet for 

24 months (Parker et al., 2006); BMR = 5% extra risk

Modela

Goodness of fit BMD5Pct

(mg/kg-d)

BMDL5Pct

p-value AIC (mg/kg-d) Basis for model selection

Multistage 1°b

Multistage 2°

Multistage 3°

Multistage 4°

0.160 164.06 31.3 15.9 All the models reduced to the multistage 

1° model, so it was selected.

4 

5 

6 

7 

8 

9 

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11

12

13

14

15

16

a

Selected model in bold; scaled residuals for selected model for doses 0, 1.5, 7, 35, and 107 mg/kg-d were −1.37, 

0.35, 0.54, 1.34, −1.05, respectively. The BMD10 and BMDL10 for the selected model were 64.2 and 32.6 mg/kg-d, 

respectively. 

b

For the multistage 2°, 3°, and 4° models, the b2, b3 and b4 coefficient estimates were 0 (boundary of parameter 

space). The models in this row reduced to the multistage 1° model.

 0

 0.05

 0.1

 0.15

 0.2

 0.25

 0.3

 0 20 40 60 80 100

Fraction Affected

dose

Multistage Cancer Model, with BMR of 5% Extra Risk for the BMD and 0.95 Lower Confidence Limit for th 

16:21 02/14 2014

BMDL BMD

 

Multistage Cancer

Linear extrapolation

Figure D-18. Plot of incidence rate by dose, with fitted curve for selected 

model, for B6C3F1 female mouse combined hepatocellular adenoma and 

carcinoma in mice exposed to RDX by diet for 24 months (Parker et al., 2006). 

BMR = 5% extra risk; dose shown in mg/kg-day.
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Multistage Cancer Model. (Version: 1.10; Date: 02/28/2013)

The form of the probability function is: P[response] = background + (1-background)*[1-

EXP(-beta1*dose^1-beta2*dose^2...)]

The parameter betas are restricted to be positive

Benchmark Dose Computation

BMR = 5% Extra risk

BMD = 31.2563

BMDL at the 95% confidence level = 15.8846

BMDU at the 95% confidence level = 136.989

Taken together, (15.8846, 136.989) is a 90% two-sided confidence interval for the BMD

Multistage Cancer Slope Factor = 0.0031477

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Parameter Estimates

Variable Estimate Default initial parameter values

Background 0.0520755 0.0658334

Beta(1) 0.00164105 0.000876864

Analysis of Deviance Table

Model Log(likelihood)

Number of

parameters Deviance

Test degrees 

freedom

of 

p-value

Full model −77.1516 5 

Fitted model −80.0315 2 5.75967 3 0.1239

Reduced model −82.5216 1 10.74 4 0.02965

AIC: = 164.063

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0.0521 3.489 1 67 −1.369

1.5 0.0544 3.373 4 62 0.351

7 0.0629 3.963 5 63 0.538

35 0.105 6.719 10 64 1.338

107 0.2047 6.347 4 31 −1.045

Chi^2 = 5.17 d.f = 3 P-value = 0.16
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1 Combined results for presence of hepatocellular or alveolar/bronchiolar adenoma or

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carcinoma in B6C3F1 female mice exposed to RDX by diet for 24 months; BMR = 10% extra 

risk 

BMD = 29.0 mg/kg-day; BMDL = 17.7 mg/kg-day

MSCOMBO results

BMR of 10% Extra Risk

**** Start of combined BMD and BMDL Calculations. 

Combined Log-Likelihood -187.3723596892213 

Combined Log-likelihood Constant 166.01737626058841 

 Benchmark Dose Computation

Specified effect = 0.1

Risk Type = Extra risk 

Confidence level = 0.95

 BMD = 28.9753

 BMDL = 17.6574

Multistage Cancer Slope Factor = 0.00566334
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1 Combined results for presence of hepatocellular or alveolar/bronchiolar adenoma or

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carcinoma in B6C3F1 female mice exposed to RDX by diet for 24 months; BMR = 5% extra 

risk 

BMD = 29.0 mg/kg-day; BMDL = 17.7 mg/kg-day

MSCOMBO results

BMR of 5% Extra Risk

** ** Start of combined BMD and BMDL Calculations.****

Combined Log-Likelihood -187.3723596892213 

Combined Log-likelihood Constant 166.01737626058841 

 Benchmark Dose Computation

Specified effect = 0.05

Risk Type = Extra risk 

Confidence level = 0.95

 BMD = 14.1062

 BMDL = 8.59627

Multistage Cancer Slope Factor = 0.00581647
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1 Rat Tumor Data -- Dose-response Analysis and BMD Modeling Documentation 

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The incidence of liver carcinomas in male F344 rats from the study by Levine et al. (1983)

was considered for quantitative dose-response analysis (see Table D-16) for comparison with other 

OSF estimates. The high-dose male group in Levine et al. (1983) had a markedly lower survival 

curve than the other dose groups, indicating a substantial number of early deaths in the high-dose 

group. In this case, a time-to-tumor analysis is preferred. Although tumor incidence was listed for 

each animal in this study, the pathology report used a different animal numbering system than the 

experimental report where the times of death were listed, and the relationship between the two 

systems was not documented. Therefore, the times of death and the tumor incidence of the animals 

could not be matched, and a time-to-tumor analysis was not possible.

Tumor incidence was modeled using the multistage-cancer models in BMDS (version 2.5). 

Because the maximum liver tumor response in the male rat was 6.4%, a BMR of 5% was used to 

model male rat liver tumor data in order to obtain a BMD and BMDL in the range of the 

experimental data, as recommended in Section 3.2 of Guidelines for Carcinogen Risk Assessment (U.S. 

EPA, 2005a). To account for the difference in the survival curves across the groups for rats, the 

number of animals alive at 12 months was used as the denominator in the analysis. These are the 

denominators listed in Table D-16. 

To estimate the human equivalent dose at the BMDL, HEDs based on both administered 

dose scaled by BW3/4 and PBPK modeling were considered. Confidence in the revised rat PBPK 

model is relatively high (see Appendix C, Section C.2.5); however, the choice of an internal dose is 

not straightforward. First, evidence regarding the involvement of metabolites has been discussed 

in the literature only in the context of the mouse, and the rate of metabolism (allometrically 

adjusted) appears to be qualitatively slower for the rat. Second, metabolism in the model 

represents the total of all pathways, whereas it is only the minor N-nitroso metabolic route, and not 

the oxidative route, that has been proposed as a factor in RDX-induced mouse carcinogenicity. 

Third, while blood concentration of RDX as an internal dose would be more proximally relevant to 

the tissue than administered dose, there are no data to indicate that the parent RDX is directly 

related to its carcinogenicity. Therefore, given the uncertainties, HEDs based on both administered 

dose scaled by BW3/4 and AUC of RDX arterial blood concentration (calculated using the PBPK 

model) are presented. Extrapolation based on the internal dose of the parent compound is 

accomplished by assuming toxicological equivalence when dose is expressed in terms of the AUC of 

the RDX blood concentration. 

The POD estimates for rat liver carcinomas are provided in Table D-21, and detailed BMD 

modeling results are provided in Table D-22. Results based on two dose-metrics are presented: 

administered dose of RDX scaled by BW3/4 (when dose is expressed in terms of mg/kg-day, this 

entails scaling by BW−1/4) and AUC of RDX arterial blood concentration (using PBPK modeling). 

Linear extrapoloation from the POD derived from these two dose-metrics resulted in candidate 

OSFs of 0.017 and 0.009 (mg/kg-day)−1, respectively. It is important to note that EPA considered 
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D-52 DRAFT―DO NOT CITE OR QUOTE

1 that the association between RDX exposure and rat liver tumors is not strong, reflecting the 

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relatively low magnitude of the rat liver carcinoma response and reduced confidence that the highdose group accurately reflects lifetime cancer incidence because, in part, of low survival (see 

discussion in Section 1.1.5). 

Table D-21. Model predictions and oral slope factor for hepatocellular 

carcinomas in male F344 rats administered RDX in the diet for 2 years (Levine 

et al., 1983)

Tumor type

Selected 

model BMR

BMD, 

mg/kg-d

BMDL, 

mg/kg-d

POD = 

BMDL05-HED,

mg/kg-d

Candidate OSFa

(mg/kg-d)-1

Hepatocellular carcinomas Multistage 1° 5% ER 28.5 11.8 2.88b, 5.75c 0.017b, 0.009c

a

Slope factor = BMR/BMDL05-HED, where BMR = 0.05 (5% extra risk). b

Based on allometric scaling of administered RDX dose; BMDL05-HED = BMDL05 × (BWa

1/4/BWh1/4), BWa = 0.25 kg, and 

BWh = 70 kg. c

Based on toxicological equivalence of PBPK model derived AUC of RDX blood concentration. 
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D-53 DRAFT―DO NOT CITE OR QUOTE

1 Table D-22. Model predictions for combined hepatocellular adenoma and 

2 

3

carcinoma in F344 rats exposed to RDX by diet for 24 months (Levine et al., 

1983); BMR = 5% extra risk

Modela

Goodness of fit BMD5Pct

(mg/kg-d)

BMDL5Pct

p-value AIC (mg/kg-d) Basis for model selection

Multistage 1°b

Multistage 2°

Multistage 3°

Multistage 4°

0.493 49.095 28.5 11.8 All the models reduced to the 

multistage 1° model, so it was 

selected.

4 

5 

6 

7 

8 

9 

a

Selected model in bold. Scaled residuals for the selected model for doses 0, 0.3, 1.5, 8, and 40 mg/kg-d were 0.89, 

−0.67, −0.74, 0.74, and −0.26, respectively. b

For the multistage 2°, 3°, and 4° models, the b2, b3 and b4 coefficient estimates were 0 (boundary of parameter 

space). The models in this row reduced to the multistage 1° model.

 0

 0.05

 0.1

 0.15

 0.2

 0.25

 0 5 10 15 20 25 30 35 40

Fraction Affected

dose

Multistage Cancer Model, with BMR of 5% Extra Risk for the BMD and 0.95 Lower Confidence Limit for th 

17:39 07/29 2014

BMDL BMD

 

Multistage Cancer

Linear extrapolation

10

11

12

13

14

15

Figure D-19. Plot of incidence rate by dose, with fitted curve for selected 

model, for combined hepatocellular adenoma and carcinoma in F344 rats

exposed to RDX by diet for 24 months (Levine et al., 1983). BMR = 5% extra 

risk; dose shown in mg/kg-day.
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

D-54 DRAFT―DO NOT CITE OR QUOTE

1 Multistage Model. (Version: 3.4; Date: 05/02/2014)

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3 

4 

5 

6 

7 

8 

9 

10

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23

The form of the probability function is: P[response] = background + (1-background)*[1-

EXP(-beta1*dose^1-beta2*dose^2...)]

The parameter betas are restricted to be positive

Benchmark Dose Computation

BMR = 5% Extra risk

BMD = 28.4525

BMDL at the 95% confidence level = 11.8487

BMDU at the 95% confidence level = 235.886

Taken together, (11.8487, 235.886) is a 90% two-sided confidence interval for the BMD

Multistage Cancer Slope Factor = 0.00421987

Parameter Estimates

Variable Estimate Default initial parameter values

Background 0.00766363 0.00949438

Beta(1) 0.00180277 0.00149364

Analysis of Deviance Table

Model Log(likelihood)

Number of

parameters Deviance

Test degrees of 

freedom p-value

Full model −21.0055 5

Fitted model −22.5473 2 3.08372 3 0.3789

Reduced model −24.4692 1 6.92747 4 0.1398

AIC: = 49.0947

Goodness of Fit Table

Dose Est. prob. Expected Observed Size

Scaled 

residuals

0 0.0077 0.421 1 55 0.894

0.3 0.0082 0.451 0 55 −0.674

1.5 0.0103 0.538 0 52 −0.737

8 0.0219 1.203 2 55 0.735

40 0.0767 2.378 2 31 −0.255

Chi^2 = 2.4 d.f = 3 P-value = 0.493
Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

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REFERENCES FOR APPENDICES

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R-2 DRAFT―DO NOT CITE OR QUOTE

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Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

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R-3 DRAFT―DO NOT CITE OR QUOTE

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Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

R-4 DRAFT―DO NOT CITE OR QUOTE

1 Pan, X; Ochoa, KM; San Francisco, MJ; Cox, S; Dixon, K; Anderson, T; Cobb, G. (2013). Absorption, 

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Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

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R-5 DRAFT―DO NOT CITE OR QUOTE

1 Simmon, V; Spanggord, R; Eckford, S; McClurg, V. (1977a). Mutagenicity of some munition 

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wastewater chemicals and chlorine test kit reagents. (ADA057680). Menlo Park, CA: SRI 

International. 

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Simmon, VF; Eckford, SL; Griffin, AF; Spanggord, R; Newell, GW. (1977b). Munitions wastewater 

treatments: Does chlorination or ozonation of individual components produce microbial 

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008X(77)90062-X

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deer mice (Peromyscus maniculatus) exposed to hexahydro-1,3,5-trinitroso-1,3,5-triazine 

(TNX). Chemosphere 75: 910-914. http://dx.doi.org/10.1016/j.chemosphere.2009.01.010

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0345-85; ADA149351). Aberdeen Proving Ground, MD: U.S. Army Environmental Hygiene 

Agency. 

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Supplemental Information―Hexahydro-1,3,5-trinitro-1,3,5-triazine

This document is a draft for review purposes only and does not constitute Agency policy.

R-6 DRAFT―DO NOT CITE OR QUOTE

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