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SCREENING-LEVEL HAZARD CHARACTERIZATION
4-Vinylcyclohexene
(CASRN 100-40-3)
The High Production Volume (HPV) Challenge Program1 was conceived as 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 sponsored chemicals; sponsorship entailed the identification and
initial assessment of the adequacy of existing toxicity data/information, conducting new testing if
adequate data did 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 Setl'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 by developing hazard characterizations (HCs). These HCs consist of an evaluation of
the quality and completeness of the data set provided in the Challenge Program submissions.
They are not intended to be definitive statements regarding the possibility of unreasonable risk of
injury to health or the environment.
The evaluation is performed according to established EPA guidance2,3 and is based primarily on
hazard data provided by sponsors; however, 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. In order to determine
whether any new hazard information was developed since the time of the HPV submission, a
search of the following databases was made from one year prior to the date of the HPV
Challenge submission to the present: (ChemID to locate available data sources including
Medline/PubMed, Toxline, HSDB, IRIS, NTP, AT SDR, IARC, EXTOXNET, EPA SRS, etc.),
STN/CAS online databases (Registry file for locators, ChemAbs for toxicology data, RTECS,
Merck, etc.), Science Direct and ECHA4. OPPT's focus on these specific sources is based on
their being of high quality, highly relevant to hazard characterization, and publicly available.
OPPT does not develop HCs for those HPV chemicals which have already been assessed
internationally through the HPV program of the Organization for Economic Cooperation and
Development (OECD) and for which Screening Initial Data Set (SIDS) Initial Assessment
Reports (SIAR) and SIDS Initial Assessment Profiles (SIAP) are available. These documents are
presented in an international forum that involves review and endorsement by governmental
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. Risk Assessment Guidelines; http://cfpub.epa.gov/ncea/raf/rafguid.cfm.
4 European Chemicals Agency, http://echa.europa.eu.
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authorities around the world. OPPT is an active participant in these meetings and accepts these
documents as reliable screening-level hazard assessments.
These hazard characterizations are technical documents intended to inform 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.
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Chemical Abstract
Service Registry Number 100-40-3
(CASRN)
Chemical Abstract Index
Name Cyclohexene, 4-ethenyl-
Structural Formula
SMILES: C(=CCCC1C=C)C1
Summary
4-Vinylcyclohexene is a colorless liquid with high vapor pressure and moderate water
solubility. It is expected to have moderate mobility in soil. Volatilization of 4-
vinyl cyclohexene is high based on its Henry's Law constant. The rate of hydrolysis is
expected to be negligible. The rate of atmospheric photooxidation is rapid. 4-
Vinylcyclohexene is not readily biodegradable.
4-Vinylcyclohexene is expected to have moderate persistence (P2) and low bioaccumulation
potential (Bl).
The acute oral and dermal toxicity of 4-vinylcyclohexene is low in rats and rabbits,
respectively and moderate in rats via the inhalation route. In 90-day inhalation toxicity studies
in rats and mice: 4-vinylcyclohexene caused decreased body weight in males and decreased
body weight gain in both sexes without concurrent changes in food consumption in rats at 6.6
mg/L; the NOAEC for systemic toxicity is 4.4 mg/L. In mice, 4-vinylcyclohexene induced
mortality in both sexes at 4.4 mg/L; the NOAEC for systemic toxicity is 1.1 mg/L. In 90-day
oral gavage repeated-dose toxicity studies in rats and mice with 4-vinylcyclohexene, mortality
was observed in females and inflammation of the non-glandular stomach was observed in both
sexes at 800 mg/kg-day; the NOAEL for systemic toxicity is 400 mg/kg-day. In the study
with mice, mortality and inflammation of the stomach were observed in males at 1200 mg/kg-
day (highest dose tested) and mortality in females was observed at 300 mg/kg-day; the
NOAELs for systemic toxicity are 600 and 150 mg/kg-day in males and females, respectively.
In a two-year NTP chronic oral gavage repeated-dose toxicity study in rats and mice with 4-
vinylcyclohexene, mortality and hyperplasia of the forestomach were observed in rats (both
sexes) at 200 mg/kg-day; the NOAEL for systemic toxicity is not established. In the same
study, mortality and histopathological changes of the stomach was observed in mice (both
sexes) at 200 mg/kg-day; the NOAEL for systemic toxicity is not established. A two-
generation oral gavage reproductive toxicity study in mice with 4-vinylcyclohexene showed a
decrease in body weight and increased liver weights; decreased pup weights, decreased sperm
concentration and histopathological changes in the ovaries at 500 mg/kg-day; the NOAEL for
systemic, reproductive and developmental toxicity is 250 mg/kg-day. In the 90-day repeated-
dose toxicity studies previously mentioned, female mice treated via inhalation showed ovarian
atrophy at 4.4 mg/L, and female mice treated orally showed a decrease in the number of
primary follicles and mature graafian follicles in the ovaries at 1200 mg/kg-day. In the two-
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year NTP oral repeated-dose toxicity studies previously mentioned, female mice treated with
200 mg/kg-day of 4-vinylcyclohexene showed tubular cell, hyperplasia granulosa cell and
papillary hyperplasia of the ovaries. 4-Vinylcyclohexene induced gene mutations in mouse
lymphoma cells but did not induce gene mutations in bacteria cells in vitro. In a sister
chromatid exchange and chromosome aberrations study, 4-vinylcyclohexene did not induce
chromosomal aberrations in mammalian cells in vitro. In micronucleus assays in mice and
rats, 4-vinylcyclohexene did not induce micronuclei in vivo. 4-Vinylcyclohexene is irritating
to mice skin, and rabbit skin and eyes. 4-Vinylcyclohexene increased the incidence of tumors
in rats and mice.
For 4-vinylcyclohexene the 96-h LC50 for fish is 4.60 mg/L and the 48-h EC50 for aquatic
invertebrates is 1.87 mg/L. There were no adequate data submitted to evaluate toxicity to
aquatic plants. The 21-d EC50, NOEC and LOEC were 0.915, 0.227 and 0.513 mg/L,
respectively, for chronic toxicity to aquatic invertebrates.
The toxicity to aquatic plants endpoint was identified as a data gap under the HPV Challenge
Program.
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The sponsor, 4-Vinylcyclohexene Group, submitted a Test Plan and Robust Summaries to EPA
for 4-vinylcyclohexene (CASRN 100-40-3; CA index name: cyclohexene, 4-ethenyl-) on
November 14, 2006. EPA posted the submission on the ChemRTK HPV Challenge website on
December 7, 2006 (http://www.epa.gov/hpv/pubs/summaries/4vinvlhx/cl6390tc.htm). EPA
comments on the original submission were posted to the website on April 30, 2009. Public
comments were also received and posted to the website. The sponsor submitted a response to
EPA's comments on July 20, 2009, which was posted to the ChemRTK website on December 7,
2009.
1. Chemical Identity
1.1 Identification and Purity
4-Vinylcyclohexene is an intermediate chemical used to produce styrene, flame retardants,
fragrances, solvents, polyoleftn products, and specialty chemicals such as vinylcyclohexene
diepoxide. Where specified the purity of 4-vinylcyclohexene is >98%.
1.2 Physical-Chemical Properties
The physical-chemical properties of 4-vinylcyclohexene are summarized in Table 1.
4-vinylcyclohexene is a colorless liquid with high vapor pressure and moderate water solubility.
Table 1. Physical-Chemical Properties of 4-Vinylcyclohexene1
Property
Value
CASRN
100-40-3
Molecular Weight
108.18
Physical State
Colorless liquid
Melting Point
-108.9°C (measured)
Boiling Point
128.9°C (measured)
Vapor Pressure
15.7 mm Hg at 25°C (measured)
Dissociation Constant
(pKa)
Not applicable
Henry's Law Constant
4.5x 10"2 atm-m3/mole (estimated)2
Water Solubility
50 mg/L at 25°C (measured)
Log Kow
3.93 (measured)
'Expcricn Health Sciences. Inc. 2009. Test Plan and Robust Summary for 4-Vinylcyclohexene. Available online
at http://www.epa.gov/chemrtk/pubs/summaries/4vinvlhx/cl6390tc.htm as of May 22, 2012.
2U.S. EPA. 2012. Estimation Programs Interface Suite™ for Microsoft® Windows, v4.10. U.S. Environmental
Protection Agency, Washington, DC, USA. Available online at
http://www.epa.gov/opptintr/exposure/pubs/episuitedl.htm as of May 22, 2012.
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2. General Information on Exposure
2.1 Production Volume and Use Pattern
4-Vinylcyclohexene (CASRN 100-40-3) had an aggregated production and/or import volume in
the United States between 1-10 million pounds during calendar year 2005.
Non-confidential information in the IUR indicated that the industrial processing and uses of the
chemical include petrochemical manufacturing as fuels. Non-confidential commercial and
consumer uses of this chemical include transportation products.
2.2 Environmental Exposure and Fate
The environmental fate properties are provided in Table 2.
Table 2. Environmental Fate Properties of 4-Vinylcyclohexene1
Property
Value
CASRN
100-40-3
Photodegradation Half-life
1.4 hours (estimated reaction with hydroxyl radicals)2
1.3 hours (estimated reaction with ozone)2
Hydrolysis Half-life
Stable
Biodegradation
0% after 28 days (not readily biodegradable)
Bioaccumulation Factor
BCF = 83-211 (measured in carp at 0.1 mg/L);
BCF = 100-208 (measured in carp at 0.01 mg/L);
BAF = 138.4 (estimated)2
Log Koc
2.6 (estimated)2
Fugacity
(Level III Model)2
Air (%)
Water (%)
Soil (%)
Sediment (%)
1.2
74
23.5
1.3
Persistence3
P2 (moderate)
Bi oaccumul ati on3
Bl (low)
'Expcricn Health Sciences. Inc. 2009. Test Plan and Robust Summary for 4-Vinylcyclohexene. Available online
at http://www.epa.gov/chemrtk/pubs/summaries/4vinvlhx/cl6390tc.htm as of May 22, 2012.
2U.S. EPA. 2012. Estimation Programs Interface Suite™ for Microsoft® Windows, v4.10. U.S. Environmental
Protection Agency, Washington, DC, USA. Available online at
http://www.epa.gov/opptintr/exposure/pubs/episuitedl.htm as of March 16, 2012.
3Federal Register. 1999. Category for Persistent, Bioaccumulative, and Toxic New Chemical Substances. Federal
Register 64, Number 213 (November 4, 1999) pp. 60194-60204.
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4-Vinylcyclohexene is expected to have moderate mobility in soil. 4-Vinylcyclohexene achieved
0% of its theoretical biochemical oxygen demand (BOD) over the course of a 28-day incubation
period using an activated sludge inoculum during the modified MITI (OECD 301C) test and is
considered not readily biodegradable. This substance is usually produced with an inhibitor to
prevent oxidation and polymerization; therefore, it is not expected to be highly persistent in the
environment. Volatilization of 4-vinylcyclohexene is high based on the Henry's Law constant.
The rate of hydrolysis is expected to be negligible. The rate of atmospheric photooxidation is
rapid. 4-Vinylcyclohexene is expected to have moderate persistence (P2) and low
bioaccumulation potential (Bl).
Conclusion: 4-Vinylcyclohexene is a colorless liquid with high vapor pressure and moderate
water solubility. It is expected to have moderate mobility in soil. Volatilization of 4-
vinylcyclohexene is high based on its Henry's Law constant. The rate of hydrolysis is expected
to be negligible. The rate of atmospheric photooxidation is rapid. 4-Vinylcyclohexene is not
readily biodegradable. 4-Vinylcyclohexene is expected to have moderate persistence (P2) and
low bioaccumulation potential (Bl).
3. Human Health Hazard
A summary of the human health toxicity data submitted for SIDS endpoints is provided in
Table 3.
Acute Oral Toxicity
Carworth-Wistar rats (five/sex/dose) were administered 4-vinylcyclohexene (purity unknown)
via oral gavage at 1660 or 3320 mg/kg and observed for 14 days following dosing. Mortality
was observed at 3320 mg/kg. OTS0522363
LDso = 2560 mg/kg
Acute Dermal Toxicity
Male New Zealand White rabbits (four/dose) were administered 4-vinylcyclohexene (purity
unknown) via the dermal route at 5, 10 or 20 mL/kg (4150, 8299 or 16,598 mg/kg) under
occluded conditions for 24 hours and observed for 14 days following dosing. Mortality was
observed at doses > 4150 mg/kg. OTS0522363
LD50 = 16,598 mg/kg
Acute Inhalation Toxicity
(1) Albino rats (six males or females/dose) were exposed to 4-vinylcyclohexene (purity
unknown) as a vapor at nominal concentrations of 4000, 8000 or 16,000 ppm (17.7, 35.4 or 70.8
mg/L; ~ 3202, 6404 or 12,808 mg/kg) for 4 hours and observed for 14 days. Mortality was
observed in 4/6 rats at 6404 mg/kg. OTS0522363
LCso = 17.7 - 35.4 mg/L
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Repeated-Dose Toxicity
(1) Sprague-Dawley Crl:CD BR rats (10/sex/dose) were exposed whole-body to 4-
vinylcyclohexene (99.8% purity) via inhalation as a vapor at nominal concentrations of 0, 250,
1000 or 1500 ppm (0, 1.1, 4.4 or 6.6 mg/L) for 6 hours/day, 5 days/week for 13 weeks (90-days).
Mean measured concentrations were identical to nominal concentrations. At 6.6 mg/L, effects
included lethargy in both sexes, statistically significant lower body weights in males and lower
body weight gains in both sexes. At > 4.4 mg/L, liver weights were increased in both sexes and
kidney weights were increased in males. In the absence of histopathological effects, changes in
liver and kidney weights were not considered adverse effects. Increased accumulation of hyaline
droplets was observed in the kidneys of male rats at all treatment doses5. No effects were
observed on food consumption, hematology, clinical chemistry or urinalysis. Additional details
were obtained from TSCATS (OTS0573005).
LOAEC = 6.6 mg/L (based on decreased body weights in males and decreased body weight
gains in both sexes without concurrent changes in food consumption)
NOAEC = 4.4 mg/L
(2) B6C3F1 mice (10/sex/dose) were exposed whole-body to 4-vinylcyclohexene (99.8 % purity)
via inhalation as a vapor at nominal concentrations of 0, 50, 250 or 1000 ppm (0, 0.22, 1.1 or 4.4
mg/L) for 6 hours/day, 5 days/week for 13 weeks (90-days). Mean measured concentrations
were 0, 53, 250 and 1000 ppm. Exposure to 4.4 mg/L resulted in the death of all males and 8/10
females. Lethargy was observed at 4.4 mg/L. The only compound-related histopathological
finding was ovarian atrophy, which was observed at 4.4 mg/L. No effects were observed on
body weight, food consumption, hematology or clinical chemistry. Additional details were
obtained from TSCATS (OTS0573005).
LOAEC = 4.4 mg/L (based on mortality in both sexes)
NOAEC = 1.1 mg/L
(3) Fischer 344 rats (10/sex/dose) were administered 4-vinylcyclohexene (> 99% pure) in corn
oil via oral gavage at 0, 50, 100, 200, 400 or 800 mg/kg-day for 5 days/week for 13 weeks (90-
days). One male died at 400 mg/kg-day and one female died at 800 mg/kg-day however, the
mortalities were not dose-dependent. Decreased body weight was observed in males at 400
mg/kg-day and in females at 800 mg/kg-day (significance not specified). Hyaline droplet
degeneration of the proximal convoluted tubule of the kidney was observed in males at 800
mg/kg-day5. Inflammation of the submucosa of the non-glandular stomach (significance not
specified) was observed in one male and three females at 800 mg/kg-day. No other treatment-
related histological abnormalities were observed.
LOAEL = 800 mg/kg-day (based on mortality in females and inflammation of the nongrandular
stomach in both sexes)
NOAEL = 400 mg/kg-day
(4) B6C3F1 mice (10/sex/dose) were administered 4-vinylcyclohexene (purity unknown) in corn
oil via oral gavage at 0, 75, 150, 300, 600 or 1200 mg/kg-day for 5 days/week for 13 weeks (90-
days). A high level of mortality (9/10 males and 4/10 females) was observed at 1200 mg/kg-day,
5 In the absence of corroborating evidence of kidney toxicity, EPA does not consider the presence of hyaline
droplets in the kidney to be an adverse effect for the purposes of determining a NOAEL or LOAEL.
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with lower mortality (2/10) in females at 300 mg/kg-day. Other deaths during the study
consisted of 1-2/10 females from 150-600 mg/kg-day which were stated in the Robust Summary
as being due to dosing errors. Body weight was reduced in females (~ 5%) at 600 mg/kg-day
and in the sole surviving male (~ 7%) at 1200 mg/kg-day. Mild acute inflammation of the
stomach was detected microscopically in both sexes at 1200 mg/kg-day. The number of primary
follicles and mature Graafian follicles was reduced in the ovaries of females at 1200 mg/kg-day.
No other treatment-related histopathological abnormalities were observed.
LOAEL (males) = 1200 mg/kg-day (based on mortality and inflammation of the stomach)
NOAEL (males) = 600 mg/kg-day
LOAEL (females) = 300 mg/kg-day (based on mortality)
NOAEL (females) = 150 mg/kg-day
(5) In an NTP study, B6C3F1 mice (50/sex/dose) were administered 4-vinylcyclohexene (> 98%
pure) in corn oil via oral gavage at 0, 200 or 400 mg/kg-day for 5 days/week for 103 weeks (2-
years). Increased mortality was observed in both sexes, 43/50 males and 33/50 females at 400
mg/kg-day. Mortality at the low dose was comparable to the control. A decrease in body weight
was also observed in females (12%) at 400 mg/kg-day by study end and a 13% decrease in male
body weight at the same dose. A significant treatment-related increase in ulcers (15%), mild
inflammation (14 and 35%) and epithelial hyperplasia (14 and 15%) of the forestomach were
observed in males at > 200 mg/kg-day. A significant increase in inflammation (22%) was
observed in females at 400 mg/kg-day. Significant treatment-related tubular cell (21 and 28%)
and granulosa cell (10%) hyperplasia of the ovary was observed in female mice at > 200 mg/kg-
day. A significant increase in congestion of the lung was observed at 400 mg/kg-day in both
sexes (72% males and 40% females). A significant increase in atrophy of the splenic red pulp
(22%) was observed in males at 400 mg/kg-day. Significant increases in histopathological
abnormalities of the adrenal gland, including alteration of the adrenal cortex (49 and 29%) and
congestion of the adrenal gland (17%) were observed in females at > 200 mg/kg-day. A 14%
increase in hepatic centrilobular congestion was observed in males at 400 mg/kg-day. Neoplastic
lesions were observed in the ovary, lung, hematopoietic system and adrenal gland. In the ovary,
mixed benign tumors, granulosa cell tumors and carcinomas increased in a dose-related manner
in female mice. Alveolar/bronchial adenomas and malignant lymphomas were observed in male
mice at 400 mg/kg-day. Capsular adenomas were observed in the adrenal gland of female mice
at 400 mg/kg-day.
LOAEL = 200 mg/kg-day (based on histopathological changes of the stomach in both sexes,
histopathology of the ovary and adrenal gland in females, adenomas and malignant lymphomas
in males and mortality at the higher dose)
NOAEL = Not established
(6) In an NTP study, Fischer 344 rats (50/sex/dose) were administered 4-vinylcyclohexene
(purity unknown) in corn oil via gavage at 0, 200 or 400 mg/kg-day for 5 days/week for 103
weeks (2-years). Mortality was observed in the control and all doses in males: control (17/50);
200 (37/50); and 400 (45/50); females: control (10/50); 200 (22/50); and 400 (36/50) atP<0.001
for all groups except 200 mg/kg-day in which P=0.022. Mortality statistical significance was
noted in both sexes at 400 mg/kg-day. Mean body weight of treated animals was comparable to
the controls except decreased body weights (5-14%) in males at 400 mg/kg-day at study week
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72. The incidence of epithelial hyperplasia of the forestomach was increased at > 200 mg/kg-
day. No other non tumor microscopic lesions were reported.
LOAEL = 200 mg/kg-day (based on mortality and epithelial hyperplasia of the forestomach in
both sexes)
NOAEL = Not established
Reproductive Toxicity
(1) In a two-generation reproductive toxicity study, CD-I (ICR) BR outbred Swiss albino mice
(25/sex/dose) were administered 4-vinylcyclohexene (purity unknown) in corn oil via gavage.
The doses for the first generation (F0) were 0, 100, 250 or 500 mg/kg-day, but only the highest
dose and control were continued for a second generation (Fl). Reproductive/developmental
parameters were measured for each generation and included mating success, number of
litters/pair, duration of gestation, number of live and dead pups/litter, pup weight, sex ratio and
pup survival and growth to post-natal day 21. Parental endpoints included food and water
consumption, body weight, organ weights, histopathology of ovaries and sperm parameters
(motility, concentration and morphology). No treatment-related mortality was observed. At 500
mg/kg-day, an 8% decrease in body weights was observed in F0 females and Fl males and
females with no concurrent changes in food and water intake. A statistical significant increase in
liver weights was observed in Fl animals at 500 mg/kg-day. Statistical significant reductions in
pup weights were observed in F0 offsprings at 500 mg/kg-day during weeks 77 and 117. An
increase in sperm motility and a decrease in sperm concentration were observed at 500 mg/kg-
day in Fl males. Examination of Fl ovaries revealed reductions in the number of primordial
oocytes/follicles by 33%, growing follicles by 55% and antral follicles by 33% in females
receiving 500 mg/kg-day.
LOAEL (systemic toxicity) = 500 mg/kg-day (based on reduced body weights and elevated
liver weights)
NOAEL (systemic toxicity) = 250 mg/kg-day
LOAEL (reproductive toxicity) = 500 mg/kg-day (based on decreased sperm concentration
and histopathological changes in the ovaries)
NOAEL (reproductive toxicity) = 250 mg/kg-day
LOAEL (developmental toxicity) = 500 mg/kg-day (based on reduced pup weights)
NOAEL (developmental toxicity) = 250 mg/kg-day
(2) In the 90-day inhalation repeated-dose toxicity study in mice described previously, ovarian
atrophy was observed at 4.4 mg/L.
(3) In the 90-day oral repeated-dose toxicity study in mice described previously, the number of
primary follicles and mature Graafian follicles was reduced in the ovaries of females at 1200
mg/kg-day.
(4) In the 2-year NTP oral repeated-dose toxicity study in mice described previously, tubular cell
hyperplasia, granulosa cell hyperplasia and papillary hyperplasia of the ovary were observed at >
200 mg/kg-day.
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Developmental Toxicity
In the two-generation reproductive toxicity study in mice previously described, a decrease in pup
weight was observed at 500 mg/kg-day.
Genetic Toxicity — Gene Mutation
In vitro
(1) In a National Toxicology Program (NTP) study, Salmonella typhimurium strains TA97,
TA98, TA100, TA104 and TA1535 were exposed to 4-vinylcyclohexene (purity unknown) in
dimethyl sulfoxide (DMSO) at concentrations up to 10,000 |ig/plate with and without metabolic
activation. Positive and negative controls were used and yielded the expected results.
Cytotoxicity was observed at 333 |ig/plate with and without activation. No increase in mutation
frequency was observed. NTP study #609542
4-Vinylcyclohexene was not mutagenic in this assay.
(2) In a NTP study, Salmonella typhimurium strains TA98, TA100, TA1535 and TA1537 were
exposed to 4-vinylcyclohexene (purity unknown) in DMSO at concentrations up to 1000
|ig/plate with and without metabolic activation. Positive and negative controls were used and
yielded the expected results. Cytotoxicity was observed at 1000 |ig/plate with activation. No
increase in mutation frequency was observed. NTP study #777152
4-Vinylcyclohexene was not mutagenic in this assay.
(3) In a NTP study, mouse lymphoma L5178Y TK+/- cells were exposed to 4-vinylcyclohexene
(purity unknown) in ethanol at concentrations ranging from 20 to 150 |ig/mL with and without
metabolic activation. Positive and negative controls were used and yielded the expected results.
Elevated mutation frequencies were observed in cells exposed to 4-vinylcyclohexene with
activation. NTP study #971117
4-Vinylcyclohexene was mutagenic in this assay.
Genetic Toxicity — Chromosomal Aberrations
In vitro
(1) In a sister chromatid exchange assay conducted by the NTP, Chinese hamster ovary (CHO)
cells were exposed to 4-vinylcyclohexene (purity unknown) in DMSO at 5, 16.7, 50 and 166.7
|ig/mL with and without metabolic activation. Positive and negative controls were used and
yielded the expected results. Exposure to 4-vinylcyclohexene did not produce an increase in
sister chromatid exchange in CHO cells with or without activation. NTP study #169960
4-Vinylcyclohexene did not induce sister chromatid exchange in this assay.
(2) In a chromosomal aberration test conducted by the NTP, CHO cells were exposed to 4-
vinylcyclohexene (purity unknown) in DMSO at 25, 49.9, 99.8 or 149.5 |ag/m L without
metabolic activation or 12.5, 25, 49.9 or 99.8 |ig/mL with activation. Positive and negative
controls were used and yielded the expected results. Exposure to 4-vinylcyclohexene did not
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produce an increase in chromosomal aberrations in CHO cells with or without activation.
Additional details were obtained from NTP study #169960.
4-Vinylcyclohexene did not induce chromosomal aberrations in this assay.
In vivo
(1) In a bone marrow micronucleus assay, B6C3Fl/CrlBR mice (5/sex/dose) were exposed to 4-
vinylcyclohexene (purity unknown) via inhalation at nominal concentrations of 0, 50, 250 or
1000 ppm for 6 hours/day for 5 days/week for 13 weeks. Mean measured concentrations were 0,
53, 250 and 1000 ppm. Mortality was observed at 1000 ppm for all male mice and half of the
female mice. Positive controls were used and responded appropriately. Exposure to
4-vinylcyclohexene did not produce an increase in the frequency of micronucleated
polychromatic erythrocytes.
4-Vinylcyclohexene did not induce micronuclei in this assay.
(2) In a bone marrow micronucleus assay, Sprague-Dawley Crl:CD BR rats (5/sex/dose) were
exposed to 4-vinylcyclohexene (purity unknown) via inhalation at nominal concentrations of 0,
250, 1000 or 1500 ppm for 6 hours/day, 5 days/week for 13 weeks. Mean measured
concentrations were identical to nominal concentrations. No mortality was observed. Positive
controls were used and responded appropriately. Exposure to 4-vinylcyclohexene did not
produce an increase in the frequency of micronucleated polychromatic erythrocytes.
4-Vinylcyclohexene did not induce micronuclei in this assay.
Additional Information
Eye Irritation
Rabbits (5/sex unspecified) were administered 0.5 mL of undiluted 4-vinylcyclohexene (purity
unknown) in one eye; the other eye served as a control. Eye irritation, consisting of minimal
corneal irritation, was scored as 2 on a scale from 1 to 10. Additional details were obtained from
TSCATS (OTS0522363).
4-Vinylcyclohexene was slightly irritating to rabbit eyes in this study.
Skin Irritation
(1) Albino rabbits (5/sex unspecified) were administered 0.01 mL of undiluted 4-
vinylcyclohexene (purity unknown) via the dermal route under open conditions for 24 hours.
Skin irritation, ranging from moderate capillary injection to marked erythema, was scored as 4
on a scale from 1 to 10. Additional details were obtained from TSCATS (OTS0522363).
4-Vinylcyclohexene was moderately irritating to rabbit skin in this assay.
(2) In a 54-week carcinogenicity study described below, male Swiss mice exposed to 4-
vinylcyclohexene via the dermal route displayed extensive skin damage.
4-Vinylcyclohexene was strongly irritating to mouse skin in this study.
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(3) In the acute dermal toxicity study described previously, New Zealand White rabbits
administered 4-vinylcyclohexene via the dermal route exhibited reddened scaly or scabby skin.
4-Vinylcyclohexene induced a crying response immediately following application, which was
interpreted as a reaction to pain.
4-Vinylcyclohexene was irritating to rabbit skin in this study.
Carcinogenicity
(1) In the 103-week oral repeated-dose NTP study in rats described previously, neoplastic
lesions were observed in the skin, urinary bladder, pituitary, preputial gland and clitoral gland.
In the skin, squamous cell papillomas and squamous carcinomas increased in a dose-dependent
manner. Neoplasms in the urinary bladder included a transitional cell papilloma and a
transitional cell carcinoma. Increases in the incidence of adenomas and carcinomas were
elevated in the anterior pituitary gland of females at 200 mg/kg-day. In the clitoral gland,
increased incidence of adenoma or squamous cell carcinoma was observed in females at 200
mg/kg-day.
4-Vinylcyclohexene increased the incidence of tumors in rats in this study.
(2) In the 103-week oral repeated-dose NTP study in mice described previously, neoplastic
lesions were observed in the ovary, lung, hematopoietic system and adrenal gland. In the ovary,
mixed benign tumors, granulosa cell tumors and carcinomas increased in a dose-related manner
in female mice. Alveolar/bronchial adenomas and malignant lymphomas were observed in male
mice at 400 mg/kg-day. Capsular adenomas were observed in the adrenal gland of female mice
at 400 mg/kg-day. The NTP concluded that the interpretation of the findings for males (tumors
in the lungs and hematopoietic system) was confounded by the poor health and low survival of
the animals, which may have resulted in artifactual temporal and statistical associations between
treatment and tumor incidence in animals dying of unrelated/undefined causes. In females, 4-
vinylcyclohexene increased the incidence of several types of uncommon ovarian tumors in a
manner that was independent of survival. It was unclear whether the incidence of adrenal gland
tumors was a direct effect of exposure or secondary to altered ovarian function.
4-Vinylcyclohexene increased the incidence of tumors in mice in this study.
(3) Male Swiss mice (30) were administered 4-vinylcyclohexene in 50% benzene via the dermal
route at 45 mg/day for 3 days/week from 8 weeks of age until their death (~ 54 weeks). Tumors
(benign and malignant) were observed in 20% of the mice receiving 4-vinylcyclohexene and in
5% of untreated mice. Only one malignant tumor (a squamous cell cancer) was observed in the
test population and in the negative controls.
4-Vinylcyclohexene increased the incidence of tumors equivocally in this study.
Conclusion: The acute oral and dermal toxicity of 4-vinylcyclohexene is low in rats and rabbits,
respectively and moderate in rats via the inhalation route. In 90-day inhalation toxicity studies in
rats and mice, 4-vinylcyclohexene decreased body weight in males and decreased body weight
gain in both sexes without concurrent changes in food consumption in rats at 6.6 mg/L; the
NOAEC for systemic toxicity is 4.4 mg/L. In mice, 4-vinylcyclohexene induced mortality in
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both sexes at 4.4 mg/L; the NOAEC for systemic toxicity is 1.1 mg/L. In 90-day oral gavage
repeated-dose toxicity studies in rats and mice with 4-vinylcyclohexene, mortality was observed
in females and inflammation of the non-glandular stomach was observed in both sexes at 800
mg/kg-day; the NOAEL for systemic toxicity is 400 mg/kg-day. In the study with mice,
mortality and inflammation of the stomach were observed in males at 1200 mg/kg-day (highest
dose tested) and mortality in females was observed at 300 mg/kg-day; the NOAELs for systemic
toxicity are 600 and 150 mg/kg-day in males and females, respectively. In a two-year NTP
chronic oral gavage repeated-dose toxicity study in rats and mice with 4-vinylcyclohexene,
mortality and hyperplasia of the forestomach were observed in rats (both sexes) at 200 mg/kg-
day; the NOAEL for systemic toxicity is not established. In the same study, mortality and
histopathological changes of the stomach was observed in mice (both sexes) at 200 mg/kg-day;
the NOAEL for systemic toxicity is not established. A two-generation oral gavage reproductive
toxicity study in mice with 4-vinylcyclohexene showed a decrease in body weight and increased
liver weights; decreased pup weights, decreased sperm concentration and histopathological
changes in the ovaries at 500 mg/kg-day; the NOAEL for systemic, reproductive and
developmental toxicity is 250 mg/kg-day. In the 90-day repeated-dose toxicity studies
previously mentioned, female mice treated via inhalation showed ovarian atrophy at 4.4 mg/L,
and female mice treated orally showed a decrease in the number of primary follicles and mature
graafian follicles in the ovaries at 1200 mg/kg-day. In the two-year NTP oral repeated-dose
toxicity studies previously mentioned, female mice treated with 200 mg/kg-day of 4-
vinylcyclohexene showed tubular cell, hyperplasia granulosa cell and papillary hyperplasia of the
ovaries. 4-Vinylcyclohexene induced gene mutations in mouse lymphoma cells but did not
induce gene mutations in bacteria cells in vitro. In a sister chromatid exchange and chromosome
aberrations study, 4-vinylcyclohexene did not induce chromosomal aberrations in mammalian
cells in vitro. In micronucleus assays in mice and rats, 4-vinylcyclohexene did not induce
micronuclei in vivo. 4-Vinylcyclohexene is irritating to mice skin, and rabbit skin and eyes. 4-
Vinylcyclohexene increased the incidence of tumors in rats and mice.
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Table 3. Summary Table of the Screening Information Data Set
as Submitted under the U.S. HPV Challenge Program -
Human Health Data
Endpoints
4-Vinylcyclohexene
000-40-3)
Acute Oral Toxicity
2560
LDso (mg/kg)
Acute Dermal Toxicity
16,598
LD50 (mg/kg)
Acute Inhalation Toxicity
17.7-35.4
LC50 (mg/L)
Repeated-Dose Toxicity
(rat; 90-d)
NOAEC/LOAEC
LOAEC = 6.6
Inhalation (mg/L)
NOAEC = 4.4
(mouse; 90-d)
LOAEC = 4.4
NOAEC = 1.1
Repeated-Dose Toxicity
(rat; 90-d)
NOAEL/LOAEL
LOAEL = 800
Oral (mg/kg-day)
NOAEL = 400
(mouse; 90-d)
LOAEL = 1200 (males);
highest dose tested
NOAEL = 600 (males)
LOAEL = 300 (females)
NOAEL = 150 (females)
(mouse; 2-y)
LOAEL = 200
NOAEL = Not Established
(rat; 2-y)
LOAEL = 200
NOAEL = Not Established
Reproductive Toxicity
NOAEL/LOAEL
Oral (mg/kg-day)
LOAEL = 500
Reproductive Toxicity
NOAEL = 250
Developmental Toxicity
NOAEL/LOAEL
(mouse)
Oral (mg/kg-day)
LOAEL = 500
Maternal/Developmental Toxicity
NOAEL = 250
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Table 3. Summary Table of the Screening Information Data Set
as Submitted under the U.S. HPV Challenge Program -
Human Health Data
Endpoints
4-Vinylcyclohexene
000-40-3)
Genetic Toxicity - Gene Mutation
In vitro
Bacteria
Mammalian Cells
Negative
Positive
Genetic Toxicity - Chromosomal
Aberrations
In vitro
Negative
Genetic Toxicity - Chromosomal
Aberrations
In vivo
Negative
(rat and mouse)
Genetic Toxicity - Other
In vitro
SCE
Negative
Additional Information
Eye Irritation
Skin Irritation
Carcinogenicity
Irritating
Irritating
Positive [Rat (Fischer)]
Positive [Mouse (B6C3F1)]
Equivocal [Mouse (Male Swiss)]
4. Hazard to the Environment
A summary of aquatic toxicity data submitted for SIDS endpoints is provided in Table 4.
Acute Toxicity to Fish
Medaka (Oryzias latipes; 1 vessel and 10 organisms per test concentration) were exposed to 4-
vinylcyclohexene (95.9 % purity) at 0 (control, solvent control), 1.0, 1.8, 3.3, 6.0, 11.0 or 20.0
mg/L under semi-static conditions for 96 hours. Dimethyl formamide and HCO-60
(polyoxyethylene hydrogenated caster oil 60) were used as solvents at 100 mg/L. Geometric
mean measured concentrations were 0 (control, solvent control), 0.62, 1.07, 1.90, 3.08, 5.98 and
11.5 mg/L. The temperature ranged from 23.5 - 23.7 °C, pH ranged from 7.0 - 7.5, and
dissolved oxygen concentrations ranged from 6.6 - 8.6 mg/L. Toxicity was based on nominal
concentrations, http://www, safe. nite. go. i p/en gli sh/db.html
96-h LCso = 4.60 mg/L
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Acute Toxicity to Aquatic Invertebrates
Water fleas {Daphnia magna; 5 per vessel with 4 vessels per test concentration) were exposed to
4-vinylcyclohexene (95.9 % purity) at 0 (control, solvent control), 0.25, 0.53, 1.1, 2.4 or 5.0
mg/L under semi-static conditions for 48 hours. Dimethyl formamide and HCO-60
(polyoxyethylene hydrogenated caster oil 60) were used as solvents at 25 mg/L. Geometric
mean measured concentrations were 0 (control, solvent control), 0.15, 0.31, 0.60, 1.41 and 2.88
mg/L. The temperature ranged from 19.9 - 20.0 °C, pH ranged from 8.1- 8.3, and dissolved
oxygen concentrations ranged from 8.4 - 8.8 mg/L. Toxicity was based on measured
concentrations, http://www.safe.nite.go.ip/english/db.html
48-h ECso = 1.87 mg/L
Toxicity to Aquatic Plants
No adequate data were available.
Chronic Toxicity to Aquatic Invertebrates
Water fleas (Daphnia magna; 1 organism per vessel with 10 vessels per test concentration) were
exposed to 4-vinylcyclohexene (95.9 % purity) at 0 (control, solvent control), 0.060, 0.160,
0.440, 1.20 or 3.20 mg/L under semi-static conditions (daily renewal) for 21 days. Dimethyl
formamide and HCO-60 (polyoxyethylene hydrogenated caster oil 60) were used as solvents at
51.2 mg/L. Geometric mean measured concentrations were 0 (control, solvent control), 0.025,
0.067, 0.227, 0.513 and 1.45 mg/L. The temperature ranged was 20.0 ± 1°C, pH ranged from 6.7
- 8.5, dissolved oxygen concentrations ranged from 7.6 - 8.8 mg/L and water hardness ranged
from 225 - 255 mg/L as CaCC>3. Toxicity was based on nominal concentrations.
http://www.safe.nite.go.ip/english/db.html
21-d ECso = 0.915 mg/L (reproduction)
21-d NOEC = 0.227 mg/L (cumulative number of juveniles produced per adult)
21-d LOEC = 0.513 mg/L (cumulative number of juveniles produced per adult)
Conclusion: For 4-vinylcyclohexene the 96-h LC50 for fish is 4.60 mg/L and the 48-h EC50 for
aquatic invertebrates is 1.87 mg/L. There were no adequate data submitted to evaluate toxicity
to aquatic plants. The 21-d EC50, NOEC and LOEC were 0.915, 0.227 and 0.513 mg/L,
respectively, for chronic toxicity to aquatic invertebrates.
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Table 4. Summary Table of the Screening Information Data Set as Submitted under
the U.S. HPV Challenge Program - Aquatic Toxicity Data
Endpoint
4-Vinylcyclohexene
(CASRN 100-40-3)
Fish
96-h LCso (mg/L)
4.60
Aquatic Invertebrates
48-h ECso (mg/L)
1.87
Aquatic Plants
72-h ECso (mg/L)
No Adequate Data
Chronic Toxicity to Aquatic
Invertebrates
21-day ECso (mg/L)
21-day NOEC (mg/L)
21-day LOEC (mg/L)
0.915
0.227
0.513
Bold = experimental data (i.e. derived from testing)
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