SCREENING-LEVEL HAZARD CHARACTERIZATION
OF HIGH PRODUCTION VOLUME CHEMICALS
SPONSORED CHEMICAL
Dimethyl 3,3'-thiobispropionate (CAS No. 4131-74-2)
[9th CI Name: Propanoic acid, 3,3'-thiobis-, dimethyl ester]
SUPPORTING CHEMICAL
Didodecyl 3,3'-thiodipropionate (CAS No. 123-28-4)
[9th CI Name: Propanoic acid, 3,3'-thiobis-, didodecyl ester]
June 2008
INTERIM
Prepared by
High Production Volume Chemicals Branch
Risk Assessment Division
Office of Pollution Prevention and Toxics
Environmental Protection Agency
1200 Pennsylvania Avenue, NW
Washington, DC 20460-0001

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SCREENING-LEVEL HAZARD CHARACTERIZATION
OF HIGH PRODUCTION VOLUME CHEMICALS
The High Production Volume (HPV) Challenge Program1 is a voluntary initiative aimed at developing and making
publicly available screening-level health and environmental effects information on chemicals manufactured in or
imported into the United States in quantities greater than one million pounds per year. In the Challenge Program,
producers and importers of HPV chemicals voluntarily sponsor chemicals; sponsorship entails the identification and
initial assessment of the adequacy of existing toxicity data/information, conducting new testing if adequate data do
not exist, and making both new and existing data and information available to the public. Each complete data
submission contains data on 18 internationally agreed to "SIDS" (Screening Information Data Set1'2) endpoints that
are screening-level indicators of potential hazards (toxicity) for humans or the environment.
The Environmental Protection Agency's Office of Pollution Prevention and Toxics (OPPT) is evaluating the data
submitted in the HPV Challenge Program on approximately 1400 sponsored chemicals. OPPT is using a hazard-
based screening process to prioritize review of the submissions. The hazard-based screening process consists of two
tiers described below briefly and in more detail on the Hazard Characterization website3.
Tier 1 is a computerized sorting process whereby key elements of a submitted data set are compared to established
criteria to "bin" chemicals/categories for OPPT review. This is an automated process performed on the data as
submitted by the sponsor. It does not include evaluation of the quality or completeness of the data.
In Tier 2, a screening-level hazard characterization is developed by EPA that consists of an objective evaluation of
the quality and completeness of the data set provided in the Challenge Program submissions. The evaluation is
performed according to established EPA guidance2'4 and is based primarily on hazard data provided by sponsors.
EPA may also include additional or updated hazard information of which EPA, sponsors or other parties have
become aware. The hazard characterization may also identify data gaps that will become the basis for a subsequent
data needs assessment where deemed necessary. Under the HPV Challenge Program, chemicals that have similar
chemical structures, properties and biological activities may be grouped together and their data shared across the
resulting category. This approach often significantly reduces the need for conducting tests for all endpoints for all
category members. As part of Tier 2, evaluation of chemical category rationale and composition and data
extrapolation(s) among category members is performed in accord with established EPA2 and OECD5 guidance.
The screening-level hazard characterizations that emerge from Tier 2 are important contributors to OPPT's existing
chemicals review process. These hazard characterizations are technical documents intended to support subsequent
decisions and actions by OPPT. Accordingly, the documents are not written with the goal of informing the general
public. However, they do provide a vehicle for public access to a concise assessment of the raw technical data on
HPV chemicals and provide information previously not readily available to the public. The public, including
sponsors, may offer comments on the hazard characterization documents.
The screening-level hazard characterizations, as the name indicates, do not evaluate the potential risks of a chemical
or a chemical category, but will serve as a starting point for such reviews. In 2007, EPA received data on uses of
and exposures to high-volume TSCA existing chemicals, submitted in accordance with the requirements of the
Inventory Update Reporting (IUR) rule. For the chemicals in the HPV Challenge Program, EPA will review the
IUR data to evaluate exposure potential. The resulting exposure information will then be combined with the
screening-level hazard characterizations to develop screening-level risk characterizations4'6. The screening-level
risk characterizations will inform EPA on the need for further work on individual chemicals or categories. Efforts
are currently underway to consider how best to utilize these screening-level risk characterizations as part of a risk-
based decision-making process on HPV chemicals which applies the results of the successful U.S. High Production
Volume Challenge Program and the IUR to support judgments concerning the need, if any, for further action.
1	U.S. EPA. High Production Volume (HPV) Challenge Program; http://www.epa.gov/chemrtk/index.htm.
2	U.S. EPA. HPV Challenge Program - Information Sources; http://www.epa.gov/chemrtk/pubs/general/guidocs.htm.
3	U.S. EPA. HPV Chemicals Hazard Characterization website (http://www.epa.gov/hpvis/abouthc.html).
4	U.S. EPA. Risk Assessment Guidelines; http://cfpub.epa.gov/ncea/raf/rafguid.cfm.
5	OECD. Guidance on the Development and Use of Chemical Categories; http://www.oecd.org/dataoecd/60/47/1947509.pdf.
6	U.S. EPA. Risk Characterization Program; http://www.epa.gov/osa/spc/2riskchr.htm.
2

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SCREENING-LEVEL HAZARD CHARACTERIZATION
Dimethyl 3,3'-thiobispropionate (CAS No. 4131-74-2)
Introduction
The sponsor, Crompton Corporation, submitted a Test Plan and Robust Summaries to EPA for dimethyl 3,3'-
thiobispropionate (CAS No. 4131-74-2; 9th CI name: propanoic acid, 3,3'-thiobis-, dimethyl ester) on September 3,
2003. EPA posted the submission on the ChemRTK HPV Challenge Web site on September 30, 2003
(http://www.epa.gov/chemrtk/pubs/summaries/dimthiat/cl4711tc.htm'). EPA comments on the original submission
were posted to the website on January 30, 2004. Public comments were also received and posted to the website.
The sponsor submitted updated/revised documents on March 18, 2004, which were posted to the ChemRTK website
on June 30, 2004.
This screening level hazard characterization is based primarily on the review of the test plan and robust summaries
of studies submitted by the sponsor(s) under the HPV Challenge Program. In preparing the hazard characterization,
EPA considered its own comments and public comments on the original submission as well as the sponsor's
responses to comments and revisions made to the submission. A summary table of SIDS endpoint data with the
structure(s) of the sponsored chemical(s) is included in the Appendix. The screening-level hazard characterization
for environmental and human health effects is based largely on SIDS endpoints and is described according to
established EPA or OECD effect level definitions and hazard assessment practices.
Justification for Supporting Chemical
Data for didodecyl 3,3'-thiodipropionate (CAS No. 123-28-4) have been used to address health effects endpoints for
dimethyl 3,3'-thiobispropionate. Both compounds are esters of thiodipropionic acid (TDPA). The submitted
toxicokinetics data show that these esters are completely absorbed and hydrolyzed to a common metabolite, TDPA,
which is further hydrolyzed and rapidly eliminated in the urine. The toxicity of both esters will essentially be the
toxicity of TDPA. EPA agrees that the use of data for didodecyl 3,3 '-thiodipropionate is appropriate.
Sum man-Conclusion
The log k of dimollis I V ^'-ihiohispropioualc mdicales dial lis potential to hioaccuniulale is expected to he low.
I lie potential of dinielhs I V ^'-ihiohispropioualc to persist mi the en\ irounieui eainiol he e\aliialed because llie
biodegradalioii endpoiiii remains a data gap
The potential lia/ard of dinielhs I V ^'-ihiohispropioualc to aquatic organisms cannot he e\ aluated because lo\icil>
data for fish, aquatic iu\ ertehrales and aquatic plants were inadequate \ll three aquatic lo\icil> endpoints remain
as data gaps
I'orthe human health eiidpoiuts. oiils data on the supporting chemical ididodccsl V ^'-thiodipropioualei are
a\ ailahle. I lie acute oral lo\icil> of didodecs I V ^'-ihiodipropiouale m rats and mice is low Repeated onil
e\posure ofdidodecs I V ^'-thiodipropiouale to rats lor I ' weeks resulted in niicroseopic lesions at the high dose
siiggestne of imocardilis (small loci of degeuei.iled or necrotic libers associated w illi minimal to moderate
mononuclear cell infiltration) Changes mi cluneal chcmisirs and uriuaKsis parameters were also seen at the high-
dose (increase iu serum cholesterol mi females, increased serum alanine and aspartate aminotransferase acli\ Hies and
decreased miliars pi I mi hotli se\esi \ll changes were re\ersihle altera 4 week reco\er\ period \o data for
reproduce e lo\icil> w ere submitted, how e\ er. no effects on the reproduce e organs w ere ohser\ ed m the repeated-
dose loMcils studs I)e\ elopnieiital lo\icil> studies conducted iu rats. mice, rahhilsaud hamsters showed no
ireainieui-relaled effects on the number of implantations, maternal and lelal sur\ i\ al and the number of \ i see nil or
skeletal abnormalities I)idodcc> I v ^'-ihiodipropioualc did not induce gcuc mutations hi bacteria iu \ itro.
chromosomal aberrations or dominant lethal effects mi \ i\ o
I lie potential health lia/ard of dinielhs I V ^'-ihiobispropiouale is low
Data gaps for the biodegradatiou. acute lo\icil> to fish, aquatic iii\ ertebrales and lo\icil> to aquatic plants endpoints
were identified under the I IPX" Challenge I'rograni
3

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1. Physical-Chemical Properties and Environmental Fate
A summary of physical-chemical and environmental fate data submitted is provided in the Appendix. For the
purpose of the screening-level hazard characterization, the review and summary of these data were limited to the
octanol-water partition coefficient and biodegradation endpoints as indicators of bioaccumulation and persistence,
respectively.
Octanol-Water Partition Coefficient
Log Kow:	0.98 (estimated)
Biodegradation
Data gap.
Conclusion: The log Kow of dimethyl 3,3'-thiobispropionate indicates that its potential to bioaccumulate is
expected to be low. The potential of dimethyl 3,3'-thiobispropionate to persist in the environment cannot be
evaluated because the biodegradation endpoint remains a data gap.
2. Environmental Effects - Aquatic Toxicity
The submitted data were inadequate to address the aquatic toxicity endpoints because the sponsor only provided
estimated data from ECOSAR. For the purposes of the HPV Challenge Program, the sponsor needs to provide
measured data on the subject chemical or predicted SAR values plus measured data on the supporting chemical.
These data were not provided as part of the revised submission.
Acute Toxicity to Fish
Data gap
Acute Toxicity to Aquatic Invertebrates
Data gap
Toxicity to Aquatic Plants
Data gap
Conclusion: The potential hazard of dimethyl 3,3'-thiobispropionate to aquatic organisms cannot be evaluated
because toxicity data for fish, aquatic invertebrates and aquatic plants were inadequate. All three aquatic toxicity
endpoints remain as data gaps.
3. Human Health Effects
Acute Oral Toxicity
Didodecyl 3,3'-thiodipropionate (CAS No. 123-28-4, Supporting Chemical)
(1) Rats (5 or 10, sex and strain not specified) were administered didodecyl 3,3'-thiodipropionate in olive oil via
gavage at 2000 or 2500 mg/kg-bw and observed for 7 days. No deaths were observed.
LD 5o > 2500 mg/kg-bw
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(2)	Rats (10 - 12 males/dose, strain not specified) were administered didodecyl 3,3'-thiodipropionate in saline via
gavage at 50, 500 or 5000 mg/kg-bw and observed for 5 days. All animals survived until necropsy on day 6 and
appeared normal. No gross morphological changes were observed.
LD so > 5000 mg/kg-bw
(3)	Mice (19, 10, 20, 20, sex and strain not specified) were administered didodecyl 3,3'-thiodipropionate in olive oil
via gavage at doses of 300, 500, 1000 or 2000 mg/kg-bw, respectively and observed for 1 week. There were 4, 0, 0
and 1 deaths at 300, 500, 1000 and 2000 mg/kg-bw, respectively.
LD 5o > 2000 mg/kg-bw
Repeated-Dose Toxicity
Didodecyl 3,3'-thiodipropionate (CAS No. 123-28-4, Supporting Chemical)
Sprague-Dawley rats (10/sex/dose) were administered didodecyl 3,3'-thiodipropionate in 1% carboxymethyl
cellulose via gavage at 0, 125, 350 or 1000 mg/kg-bw/day for 13 weeks, followed by a 4-week recovery period. No
mortality occurred and no clinical signs of toxicity were observed. No treatment-related effects on food
consumption, body weight, ophthalmological examination, hematology parameters or organ weights were seen.
Findings noted at 1000 mg/kg-bw/day included a minor increase in serum cholesterol concentrations in females and
increased serum alanine and aspartate aminotransferase activities and decreased urinary pH in both sexes. Gross
pathology findings were considered to be incidental or unrelated to treatment. Microscopic lesions in the heart
suggestive of myocarditis were described as small foci of degenerated or necrotic fibers associated with minimal to
moderate mononuclear cell infiltration. All changes were reversible after 4 weeks recovery period. No treatment-
related findings were seen at 125 or 350 mg/kg-bw/day.
LOAEL = 1000 mg/kg-bw/day (based on histopathological lesions of the heart)
NOAEL = 350 mg/kg-bw/day
Reproductive Toxicity
No data for reproductive toxicity were submitted. Evaluation of effects on reproductive organs from the 13-week
repeated-dose toxicity study, a dominant lethal assay and the developmental toxicity study adequately addresses the
reproductive toxicity endpoint for the purposes of the HPV Challenge Program.
Didodecyl 3,3'-thiodipropionate (CAS No. 123-28-4, Supporting Chemical)
(1)	In the repeated-dose toxicity study in rats described previously, reproductive organs that were examined
histologically included the epididymides, mammary glands, ovaries, prostate, seminal vesicles, testes and uterus
(horn + cervix). No macroscopic or microscopic changes in the reproductive organs were observed at any dose-
level.
(2))	Rats (10 males/dose) were administered didodecyl 3,3'-thiodipropionate via gavage at 50, 500 or 5000 mg/kg-
bw/day for 5 days. Following treatment, each rat was sequentially mated with two females per week for 8 weeks.
Females were sacrificed 14 days after separation from the male and the uterus was examined for early deaths, late
fetal deaths and total implantations. There was no clear pattern of either increases or decreases between the control
and treatment groups at any dose in any of the parameters studied. Positive and negative controls were tested
concurrently; however, the results were not provided.
Didodecyl 3,3'-thiodipropionate did not induce dominant lethal effects in this assay.
Developmental Toxicity
Didodecyl 3,3'-thiodipropionate (CAS No. 123-28-4, Supporting Chemical)
(1) Pregnant Wistar rats (19 - 21/dose) were administered didodecyl 3,3'-thiodipropionate (in corn oil) via gavage at
16, 74, 350 or 1600 mg/kg-bw/day on days 6 - 15 of gestation. Caesarian sections were performed on day 20 of
gestation. No adverse effects were found with respect to implantations, maternal and fetal survival and visceral or
skeletal abnormalities. A positive control group was treated with 250 mg/kg-bw of aspirin; however, the results
were not provided.
NOAEL (maternal and developmental toxicity) = 1600 mg/kg-bw/day (based on no effects at the highest dose
tested)
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(2)	Pregnant female CD-I mice (20 - 22/dose) were administered didodecyl 3,3'-thiodipropionate in corn oil via
gavage at 16, 74, 350 or 1600 mg/kg-bw/day on days 6 - 15 of gestation. Caesarian sections were performed on day
17 of gestation. No adverse effects were found with respect to implantations, maternal and fetal survival and
visceral or skeletal abnormalities. A positive control group was treated with 150 mg/kg-bw of aspirin; however, the
results were not provided.
NOAEL (maternal and developmental toxicity) = 1600 mg/kg-bw/day (based on no effects at the highest dose
tested)
(3)	Pregnant female Dutch rabbits (15 - 29/dose) were administered didodecyl 3,3'-thiodipropionate in corn oil via
gavage at 2.5, 10, 45, 216 or 1000 mg/kg-bw/day on days 6 - 18 of gestation. The number of pregnant rabbits at the
end of the study ranged from 8 - 13/dose, all of which survived to term. Caesarian sections were performed on day
29 of gestation. There were no clear treatment-related effects on the number of implantations, maternal and fetal
survival and visceral or skeletal abnormalities.
NOAEL (maternal and developmental toxicity) = 1000 mg/kg-bw/day (based on no effects at the highest dose
tested)
(4)	Pregnant female Golden hamsters (20 - 23/dose) were administered didodecyl 3,3'-thiodipropionate in corn oil
via gavage at 16, 74, 350 or 1600 mg/kg-bw/day on days 6 - 10 of gestation. Caesarian sections were performed on
day 14 of gestation. The numbers of implantations and maternal and fetal survival were not adversely affected at
any dose and visceral or skeletal tissue changes were comparable to the sham controls.
NOAEL (maternal and developmental toxicity) = 1600 mg/kg-bw/day (based on no effects at the highest dose
tested)
Genetic Toxicity - Gene Mutation
In vitro
Didodecyl 3,3'-thiodipropionate (CAS No. 123-28-4, Supporting Chemical)
Salmonella typhimurium strains TA1535, TA1537, TA1538 and TA98 and Escherichia coli strain WP2 were
exposed to didodecyl 3,3'-thiodipropionate at 33.3, 100, 333, 2500, 3333, 5000, 6667 or 10,000 (ig/plate and ,V.
typhimurium strain TA100 was exposed to 3.3 or 10 (ig/plate, all in the presence and absence of metabolic
activation. Positive controls were tested concurrently; however, the results were not provided. A precipitate was
observed at the two highest doses. No evidence of mutagenic activity was noted at any dose either in the presence
or absence of metabolic activation.
Didodecyl 3,3'-thiodipropionate was not mutagenic in this assay.
Genetic Toxicity - Chromosomal Aberrations
Didodecyl 3,3'-thiodipropionate (CAS No. 123-28-4, Supporting Chemical)
In vivo
(1)	Albino rats (five males/dose) were administered didodecyl 3,3'-thiodipropionate via gavage at 50, 500 or 5000
mg/kg-bw and sacrificed 6, 24 or 48 hours after dosing. Positive and negative controls were tested concurrently;
however, the results were not provided. No chromosomal aberrations were observed and mitotic indices were
normal.
Didodecyl 3,3'-thiodipropionate did not induce chromosomal aberrations in this assay.
(2)	Rats (10 males/dose) were administered didodecyl 3,3'-thiodipropionate via gavage at 50, 500 or 5000 mg/kg-
bw/day for 5 days. Following treatment, each rat was sequentially mated with two females per week for 8 weeks.
Females were sacrificed 14 days after separation from the male and the uterus was examined for early deaths, late
fetal deaths and total implantations. There was no clear pattern of either increases or decreases between the control
and treatment groups at any dose in any of the parameters studied. Positive and negative controls were tested
concurrently; however, the results were not provided.
Didodecyl 3,3'-thiodipropionate did not induce dominant lethal effects in this assay.
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Conclusion: For the human health endpoints, only data on the supporting chemical (didodecyl 3,3 '-
thiodipropionate) are available. The acute oral toxicity of didodecyl 3,3'-thiodipropionate in rats and mice is low.
Repeated oral exposure of didodecyl 3,3'-thiodipropionate to rats for 13 weeks resulted in microscopic lesions at the
high dose suggestive of myocarditis (small foci of degenerated or necrotic fibers associated with minimal to
moderate mononuclear cell infiltration). Changes in clinical chemistry and urinalysis parameters were also seen at
the highest dose (increase in serum cholesterol in females, increased serum alanine and aspartate aminotransferase
activities and decreased urinary pH in both sexes). All clinical chemistry changes were reversible after a 4 week
recovery period. No data for reproductive toxicity were submitted; however, no effects on the reproductive organs
were observed in the repeated-dose toxicity study. Developmental toxicity studies conducted in rats, mice, rabbits
and hamsters showed no treatment-related effects on the number of implantations, maternal and fetal survival and
the number of visceral or skeletal abnormalities. Didodecyl 3,3'-thiodipropionate did not induce gene mutations in
bacteria in vitro, chromosomal aberrations or dominant lethal effects in vivo.
The potential health hazard of dimethyl 3,3'-thiobispropionate is low.
4. Hazard Characterization
The log Kow of dimethyl 3,3'-thiobispropionate indicates that its potential to bioaccumulate is expected to be low.
The potential of dimethyl 3,3 '-thiobispropionate to persist in the environment cannot be evaluated because the
biodegradation endpoint remains a data gap.
The potential hazard of dimethyl 3,3 '-thiobispropionate to aquatic organisms cannot be evaluated because toxicity
data for fish, aquatic invertebrates and aquatic plants were inadequate. All three aquatic toxicity endpoints remain
as data gaps.
For the human health endpoints, only data on the supporting chemical (didodecyl 3,3 '-thiodipropionate) are
available. The acute oral toxicity of didodecyl 3,3'-thiodipropionate in rats and mice is low. Repeated oral
exposure of didodecyl 3,3'-thiodipropionate to rats for 13 weeks resulted in microscopic lesions at the high dose
suggestive of myocarditis (small foci of degenerated or necrotic fibers associated with minimal to moderate
mononuclear cell infiltration). Changes in clinical chemistry and urinalysis parameters were also seen at the high-
dose (increase in serum cholesterol in females, increased serum alanine and aspartate aminotransferase activities and
decreased urinary pH in both sexes). All changes were reversible after a 4 week recovery period. No data for
reproductive toxicity were submitted; however, no effects on the reproductive organs were observed in the repeated-
dose toxicity study. Developmental toxicity studies conducted in rats, mice, rabbits and hamsters showed no
treatment-related effects on the number of implantations, maternal and fetal survival and the number of visceral or
skeletal abnormalities. Didodecyl 3,3'-thiodipropionate did not induce gene mutations in bacteria in vitro,
chromosomal aberrations or dominant lethal effects in vivo.
The potential health hazard of dimethyl 3,3'-thiobispropionate is low.
5. Data Gaps
Data gaps for the biodegradation, acute toxicity to fish, aquatic invertebrates and toxicity to aquatic plants endpoints
were identified under the HPV Challenge Program.
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APPENDIX
Summary Tabic of the Screening Information Data Set
as Submitted under the U.S. HPV Challenge Program
Endpoints
SPONSORED CHEMICAL
Dimethyl 3,3'-thiobispropionatc
(4131-74-2)
SUPPORTING CHEMICAL
Didodccyl 3,3'-thiodipropionatc
(123-28-4)
Structure
0 0

Summary of Physical-Chemical Properties and Environmental Fate Data
Melting Point (C)
Liquid at room temperature.
-
Boiling Point (C)
130 C (2.67 hPa) - 148 C (24 hPa)
-
Vapor Pressure
(hPa at 25C)
	

Log Kw
0.98 (estimated)
-
Indirect (OH) Photodegradation
Half-life (t1/2)
6.2 h (estimated)
_
Stability in Water (Hydrolysis)
(ti/2)
1.02 y (estimated atpH 7), 37.14 d
(estimated at pH 8)
-
Fugacity
(Level III Model)
Air (%)
Water (%)
Soil (%)
Sediment (%)
0.01
42
57.9
0.0757
-
Biodegradation at 28 days (%)
Data gap.
-
Summary of Environmental Effects-Aquatic Toxicity Data
Fish
96-h LCS0 (mg/L)
Data gap.
_
Aquatic Invertebrates
48-h EC50 (mg/L)
Data gap.
_
Aquatic Plants
72-h ECS0 (mg/L)
(growth)
(biomass)
Data gap.
-
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Summarv Tabic of the Screening Information Data Set
as Submitted under the U.S. HPV Challenge Program
Endpoints
SPONSORED CHEMICAL
Dimethyl 3,3'-thiobispropionate
(4131-74-2)
SUPPORTING CHEMICAL
Didodecyl 3,3'-thiodipropionatc
(123-28-4)
Summary of Human Health Data
Acute Oral Toxicity
LDS0 (mg/kg-bw)

>2000
Repeated-Dose Toxicity
NOAEL/LOAEL
Oral (mg/kg-bw/day)
-
NOAEL = 350
I.OAF.I. = 1000
Reproductive Toxicity
NOAEL/LOAEL
Oral (mg/kg-bw/day)
-
No effects were seen on reproductive
organs in the repeated-dose toxicity
study in rats.
Developmental Toxicity
NOAEL/LOAL
Oral (mg/kg-bw/day)
Maternal and Developmental
Toxicity
-
(rat)
NOAEL = 1600 (hdt)
(mouse)
NOAEL = 1600 (hdt)
(rabbit)
NOAEL = 1000 (hdt)
(hamster)
NOAEL = 1600 (hdt)
Genetic Toxicity - Gene Mutation
In vitro
-
Negative
Genetic Toxicity - Chromosomal
Aberrations
In vitro

Negative
Genetic Toxicity - Chromosomal
Aberrations
In vivo
-
Negative
- Indicates that endpoint was not addressed for this chemical,
hdt = highest dose tested
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