Screening-level Hazard Characterization of High Production Volume Chemicals Sponsored Chemical 2 4 6-trimethylphenol (cas No. 527-60-6) [9th Ci Name Phenol 2 4 6-trimethyl-] October 2007 Interim


SCREENING-LEVEL HAZARD CHARACTERIZATION
OF HIGH PRODUCTION VOLUME CHEMICALS

SPONSORED CHEMICAL

2,4,6-Trimethylphenol (CAS No. 527-60-6)
[9th CI Name: Phenol, 2,4,6-trimethyl-]

October 2007
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.

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SCREENING-LEVEL HAZARD CHARACTERIZATION
2,4,6-Trimethylphenol (CAS No. 527-60-6)

Introduction

The sponsor, General Electric Company, submitted a Test Plan and Robust Summaries to EPA for 2,4,6-
trimethylphenol (CAS No 527-60-6; 9th CI name: Phenol, 2,4,6-trimethyl-) on December 30, 2002. EPA posted the
submission on the ChemRTK HPV Challenge website on January 30, 2003

(http://www.epa.gov/chemrtk/pubs/summaries/246trime/cl4218tc.htm'). EPA comments on the original submission
were posted to the website on June 16, 2003. Public comments were also received and posted to the website. The
sponsor submitted updated/revised documents on August 5, 2003 and December 29, 2005, which were posted to the
ChemRTK website on September 5, 2003 and March 16, 2006, respectively.

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 toxicity is based largely on SIDS endpoints and is described according to
established EPA or OECD effect level definitions and hazard assessment practices.

Sum m an-Conclusion

The lou k i»f 2.4.<>-iiiniclh\ Iphenol indicates that lis potential to bioacciininlatc is c\pectcd to he low.

2.4.(<- l riincl11> Iphenol is not readiK biodegradable, indicating dial il has ihc potential to persist in ilie en\ iroiiniciit.

The e\ ahiatioii of a\ ailable to\icit> dala lor fish. aquatic 11in eriebrales and aquatic plants indicates that the potential
acute ha/aid of 2.4.<>-iiiniclh\ Iphenol to aquatic organisms is moderate

\cnte oral and dermal to\icit\ of 2.4.<>-iiiniclh\ Iphenol is low In a combined repeated-

dose reproducee de\elopniental to\icit> screening test in rats, the follow ing effects were noted at the highest dose
tested, increased serum potassium in I'u males, decreased serum albumin and cholesterol mi I'n males, increased
lh\ nms-io-bod\ weight ratios and increased th\ niiis-io-brain weight ratios in I'I females, increased hematocrit and
decreased tail pinch response in I'u females, increased glucose in I I adult females, decreased bod> weight in I I
females at post-natal da> 22 2.4.<>-Tiinicth\ Iphenol was not mutagenic in viini in bacterial cells and results from in
viini mouse l\ niphonia assa\ were et|in\ ocal 2.4.<>-Tiiniclh\ Iphenol induced structural chromosomal aberrations in
( I l() cells mi the presence of metabolic acli\ ation ()\ enill. the weight of e\ idence suggest that 2.4.<>-
trinielhs Iphenol has potential to cause mutagenic effects. specificalK in the presence of metabolic acli\ ation

I lie potential health ha/ard of 2.4.<>-innielh\ Iphenol is modenite based on repeated-dose and

reprodiicliN e de\ elopniental to\icit> \\ ailable data suggests that 2.4.(>-tiinielh\ Iphenol has the potential to be

genoioMc

\o data gaps were identified imder the I ll'Y ( hallenge I'rogiani

1. Physical-Chemical Properties and Environmental Fate

A summary of physical-chemical properties and environmental fate data submitted is provided in Table 1. For the
purpose of the screening-level hazard characterization, the review and summary of these data was limited to the
octanol-water partition coefficient and biodegradation endpoints as indictors of bioaccumulation and persistence,
respectively.

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Octanol-Water Partition Coefficient

Log Kow: 2.73
Biodegradation

In an aerobic biodegradation study using activated sludge as inoculum (0.05 ml/L) and 1.68 mg/L of
2,4,6-trimethylphenol, 11.3% 2,4,6-trimethylphenol had degraded after 28 days.

2,4,6-Trimethylphenol is not readily biodegradable.

Conclusion: The log Kow of 2,4,6-trimethylphenol indicates that its potential to bioaccumulate is expected to be
low. 2,4,6-Trimethylphenol is not readily biodegradable, indicating that it has the potential to persist in the
environment.

2. Environmental Effects - Aquatic Toxicity
Acute Toxicity to Fish

Rainbow trout (Oncorhynchus mykiss) were exposed to 2,4,6-trimethylphenol at nominal concentrations of 0, 0.8,
1.7, 3.8, 8.3, 18.2 or 40 mg/L under static conditions for 96 hours. Analysis of the 0.8, 8.3 and 40 mg/L treatment
solutions showed the measured concentrations were within 20% of the nominal concentrations. All fish at 18.2 and
40 mg/L died within 3 hours of exposure.

96-h LCS0 = 9.7 mg/L

Acute Toxicity to Aquatic Invertebrates

(1)	Daphnia magna were exposed to 2,4,6-trimethylphenol at measured concentrations of 0, 0.8, 1.7, 3.8, 8.3, 18.2
or 40 mg/L under static conditions for 24 hours. A subset of test solutions were measured at the start and end of the
experiment.

24-h ECS0 = 3.5 mg/L

(2)	Daphnia magna were exposed exposed to 2,4,6-trimethylphenol at measured concentrations of 0, 0.1, 0.35, 1.0,
3.5, 100 or 350 mg/L under static conditions for 24 hours. Acetone was used as a solvent dispersant. Test solution
concentrations were not measured.

24-h ECS0 = 28.95 mg/L

(3)	In response to the original submission that included 24-hour daphnid test data, but not the normally required 48-
hour daphnid test data, EPA requested that the submitter support the 24-hour data with structure-activity estimates or
measured data for an analogous chemical. In the revised submission, neither was provided. Therefore, EPA
estimated a 48-hour LC50 for Daphnia magna using the EPA's ECOSAR Program

(http://www.epa. gov/oppt/newchems/tools/2 lecosar.html in order to confirm the robustness of the 24-hour data.
The modeled results for the 48-hour test were in good agreement with the 24-hour results for the test conducted
without a solvent and with analytical confirmation of the water concentrations. Therefore, the 24-hour data from
that test were accepted for the purpose of the HPV Challenge Program.

48-h EC50 = 2.48 mg/L (estimated)

Toxicity to Aquatic Plants

Pseudokirchneriella subcapitata were exposed to 2,4,6-trimethylphenol at concentrations of of 0, 0.82, 2.05, 5.12,
12.8, 32.0 or 80.0 mg/L under static conditions for 96 hours.

72-h EC50 (biomass) = 2.54 mg/L
72-h EC50 (growth) = 5.59 mg/L

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Conclusion: The evaluation of available toxicity data for fish, aquatic invertebrates and aquatic plants indicates that
the potential acute hazard of 2,4,6-trimethylphenol to aquatic organisms is moderate.

3. Human Health Effects
Acute Oral Toxicity

Albino rats (3/sex) were administered 2,4,6-trimethylphenol as a single oral dose of 2000 mg/kg-bw. No mortality
was observed. Piloerection was the major clinical sign, which resolved by day 4 of the study.

LDS0 > 2000 mg/kg-bw

Acute Dermal Toxicity

New Zealand White rabbits were administered 2,4,6-trimethylphenol as a single, occlusive dermal application of
2000 mg/kg-bw for 24 hours. After removal of the test substance 24 hours later, necrosis was observed at the site of
application in 6 out of 10 animals. The necrotic areas remained visible for the duration of the study. Slight to
moderate erythema and edema was observed in the remaining four animals. No mortality or overt signs of systemic
toxicity were evident during the study.

LDS0 > 2000 mg/kg-bw

Repeated-Dose Toxicity

In a combined repeated-dose/reproductive/developmental toxicity screening test, Sprague-Dawley rats (10/sex/dose)
were administered 2,4,6-trimethylphenol in corn oil via gavage at doses of 0, 10, 100 or 200 mg/kg-bw/day for 2
weeks prior to mating and during a 2-week mating period through 3 weeks of gestation and lactation (F0 parents). A
2-week recovery group of five additional males and females per group (at 0 and 200 mg/kg-bw/day) was also
included. Five additional females (not mated) were dosed at 0 and 200 mg/kg-bw/day for 28 days and subsequently
sacrificed (28-day females). Selected F1 offspring (10/sex/treatment) were dosed from weaning through scheduled
sacrifice approximately 7 weeks post-weaning (F1 adults). The study summary concluded that except for signs of a
taste aversion response (dose-related incidences of rooting); no systemic toxicity was noted. The study reported a
NOAEL of > 200 mg/kg-bw/day. However, the data tables presented in the robust summary show trends and noted
statistically significant differences in the following parameters when compared with controls:

F0Males: increased serum potassium levels at 10 (p < 0.01), 100 (p < 0.001) and 200 (p < 0.05) mg/kg-bw/day;
decreased serum albumin levels at 100 (p < 0.01) and 200 (p < 0.05) mg/kg-bw/day; and decreased total protein
levels at 100 (p < 0.01) and 200 (p < 0.01) mg/kg-bw/day.

F0 Females: increased hematocrit at 200 mg/kg-bw/day (p < 0.05); decreased tail pinch response at 200 mg/kg-
bw/day (p < 0.01).

F1 Males: increased liver (relative-to-brain weight) at 200 mg/kg-bw/day (p < 0.05) and increased incidence of

renal nephropathy (4/10) at 200 mg/kg-bw/day.

F1 Females: increased glucose level at 200 mg/kg-bw/day (p < 0.05).

Recovery Males: increased adrenal weight (absolute and relative-to-body weight) at 200 mg/kg-bw/day (p < 0.05).
28-Day females: decreased hind-limb grip strength at 200 mg/kg-bw/day (p < 0.05).

LOAEL = 10 mg/kg-bw/day (based on statistically significant changes in serum potassium)

NOAEL = Not established

Reproductive Toxicity

In the combined repeated-dose/reproductive/developmental toxicity screening test described previously, the
following trends or statistically significant differences in the following parameters were seen when compared with
controls:

F0 Females: fluid-filled uterus in 1 of 10 animals receiving 100 mg/kg-bw/day and 'retained fetus in uterus' was
reported in 1 of 10 females receiving 200 mg/kg-bw/day while no such effect was observed in control animals.
Gestational length appeared to be reduced in animals receiving 200 mg/kg/day when compared to controls. Post-
implantation loss/litter was reported approximately twice as many times as controls in females receiving 200 mg/kg-
bw/day.

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Recovery females (FO): fluid-filled uterus was reported in 1 of 5 females dosed at 200 mg/kg-bw/day.

F1 Females: fluid-filled uterus was reported in all treatment groups. There was a trend showing an increase in

adjusted age at vaginal opening compared to control animals (unable to determine significance).

28-Day females: fluid-filled uterus was reported in 2 of 5 animals receiving 200 mg/kg-bw/day.

LOAEL (systemic and reproductive toxicity) = 10 mg/kg/day (based on effect on fluid-filled uterus in F1

females)

NOAEL (systemic and reproductive toxicity) = Not established

Developmental Toxicity

In the combined repeated-dose/reproductive/developmental toxicity screening test described previously, the
following trends or statistically significant differences in the following parameters when compared with controls:
F0 Females: see Reproductive Toxicity section.

F1 Offspring (male and female pups): reduced pup growth (pup weight/litter) from postnatal day 7 to 21 at 100 and
200 mg/kg-bw/day.

F1 Females (postnatal day 21): increased thymus-to-body weight ratio at 100 and 200 mg/kg-bw/day (p < 0.001);
increase in thymus-to-brain weight ratio at 200 mg/kg-bw/day (p < 0.01); and a trend of increasing adjusted age at
vaginal opening compared to control animals (unable to determine significance).

LOAEL (maternal) = 10 mg/kg-bw/day (based on fluid-filled uterus inFl females; see reproductive toxicity
section)

NOAEL (maternal) = Not established

LOAEL (developmental toxicity) = 100 mg/kg-bw/day (based on effects on thymus)

NOAEL (developmental toxicity) = 10 mg/kg-bw/day

Genetic Toxicity - Gene Mutation

In vitro

(1)	In an Ames assay, Salmonella typhimurium strains TA98, TA100, TA1535 and TA1537 were exposed to 2,4,6-
trimethylphenol at concentrations of 0, 0.03, 0.3, 3 and 30 (imol/plate; with and without metabolic activation. The
number of revertants/plate at all concentrations in all tester strains was less than the number reported in the negative
control group, with and without metabolic activation. Positive control response was not indicated in the robust
summary.

2,4,6-Trimethylphenol was not mutagenic in this assay.

(2)	Mouse lymphoma L5178Y cells were exposed to 2,4,6-trimethylphenol at test concentrations of 0, 10, 30, 40, 50
or 100 (ig/mL with metabolic activation and 0, 50, 75, 100, 125 or 150 (ig/mL without metabolic activation.
Mutations were equivocal in the absence of metabolic activation at 4- and 24-hour exposures and negative in the
presence of metabolic activation.

2,4,6-Trimethylphenol gave equivocal results in this assay.

Genetic Toxicity - Chromosomal Aberrations
In vitro

Chinese hamster ovary (CHO) cells were exposed for 4 hours to 2,4,6-trimethylphenol at concentrations of 0, 25, 50,
100, 150, 200, or 300 (ig/mL without metabolic activation and at concentrations of 0, 12.5, 25, 50, 100, 150 or 200
|ig/ with metabolic activation. In addition, cells were exposed for 20 hours to concentrations of 0, 25, 50, 100, 150,
200 300 or 400 (ig/mL without metabolic activation for the 20 hours. Mitomycin C and cyclophosphamide were
used as the positive controls and DMSO was used as the solvent control. Cytotoxic concentrations were greater than
136 and 408 ng/mL with and without metabolic activation, respectively. 2,4,6-trimethylphenol did not induce
structural and numerical chromosome aberrations without metabolic activation system. In the presence of metabolic
activation, 2,4,6-trimethylphenol was negative for numerical chromosomal aberrations but induced statistically
significant (p < 0.01 at 100 ng/mL and p < 0.05 at 200 ng/mL) structural chromosomal aberrations.
2,4,6-Trimethylphenol induced chromosomal aberrations in this assay.

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In vivo

Male and female mice were administered 2,4,6-trimethylphenol at concentrations of 0, 500, 1000, 1200, 1400 and
1600 mg/kg-bw via intraperitoneal injection. The vehicle was corn oil and the positive control was
cyclyphosphamide. The number of micronucleated polychromatic erythrocytes (MPCEs) per 1000 PCEs in treated
groups was not statistically increased relative to the respective vehicle controls in either male or female mice,
regardless of dose level or bone marrow collection time. Positive and negative (vehicle) control results indicated
appropriate responses.

2,4,6-Trimethylphenol did not increase MPCEs in this assay.

Conclusion: Acute oral and dermal toxicity of 2,4,6-trimethylphenol is low. In a combined repeated-
dose/reproductive/developmental toxicity screening test in rats, the following effects were noted at the highest dose
tested: increased serum potassium in F0 males, decreased serum albumin and cholesterol in F0 males, increased
thymus-to-body weight ratios and increased thymus-to-brain weight ratios in F1 females, increased hematocrit and
decreased tail pinch response in F0 females, increased glucose in F1 adult females, decreased body weight in F1
females at post natal day 22. 2,4,6-trimethylphenol was not mutagenic in vitro in bacterial cells and results from in
vitro mouse lymphoma assay were equivocal. 2,4,6-trimethylphenol induced structural chromosomal aberrations in
CHO cells in the presence of metabolic activation. Overall, the weight of evidence suggest that 2,4,6-
trimethylphenol has potential to cause mutagenic effects, specifically in the presence of metabolic activation.

The potential health hazard of 2,4,6-trimethylphenol is moderate based on repeated-dose and
reproductive/developmental toxicity. Available data suggests that 2,4,6-trimethylphenol has the potential to be
genotoxic.

4. Hazard Characterization

The log Kow of 2,4,6-trimethylphenol indicates that its potential to bioaccumulate is expected to be low.
2,4,6-Trimethylphenol is not readily biodegradable, indicating that it has the potential to persist in the environment.

The evaluation of available toxicity data for fish, aquatic invertebrates and aquatic plants indicates that the potential
acute hazard of 2,4,6-trimethylphenol to aquatic organisms is moderate.

Acute oral and dermal toxicity of 2,4,6-trimethylphenol is low. In a combined repeated-

dose/reproductive/developmental toxicity screening test in rats, the following effects were noted at the highest dose
tested: increased serum potassium in F0 males, decreased serum albumin and cholesterol in F0 males, increased
thymus-to-body weight ratios and increased thymus-to-brain weight ratios in F1 females, increased hematocrit and
decreased tail pinch response in F0 females, increased glucose in F1 adult females, decreased body weight in F1
females at post-natal day 22. 2,4,6-Trimethylphenol was not mutagenic in vitro in bacterial cells and results from in
vitro mouse lymphoma assay were equivocal. 2,4,6-Trimethylphenol induced structural chromosomal aberrations in
CHO cells in the presence of metabolic activation. Overall, the weight of evidence suggest that 2,4,6-
trimethylphenol has potential to cause mutagenic effects, specifically in the presence of metabolic activation.

5. Data Gaps

No data gaps 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
2,4,6-T rimethylphenol

(527-60-6)

Structure

OH

H,C^ Js. /CH,

\ ll

ch3

Summary of Physical-Chemical Properties and Environmental Fate Data

Melting Point (°C)

73

Boiling Point (°C)

220

Vapor Pressure
(hPa at 25°C)

0.07

Log K„w

2.73

Water Solubility
(mg/L at 25°C)

1.01x103

Direct Photodegradation

—

Indirect (OH ) Photodegradation
Half-life (t1/2)

8.2 h (estimated)

Stability in Water (Hydrolysis) (ti/2)

Not susceptible under environmental conditions

Fugacity
(Level III Model)

Air (%)
Water (%)
Soil (%)
Sediment (%)

0.773
31.7
67.2
0.336

Biodegradation at 28 days (%)

11.3

Not readily biodegradable

Summary of Environmental Effects - Aquatic Toxicity Data

Fish

96-h LCS0 (mg/L)

9.7

Aquatic Invertebrates
48-h ECS0 (mg/L)

3.5 (24-h)
28.95 (24-h)
2.48 (estimated)

Aquatic Plants
72-h ECS0 (mg/L)
(growth)
(biomass)

5.59
2.54

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Summary Tabic of the Screening Information Data Set
as Submitted underthe U.S. HPV Challenge Program

Endpoints

SPONSORED CHEMICAL
2,4,6-T rimethylphenol

(527-60-6)

Summary of Human Health Data

Acute Oral Toxicity
LDS0 (mg/kg-bw)

>2000

Acute Dermal Toxicity
LDS0 (mg/kg-bw)

>2000

Repeated-Dose Toxicity
NOAEL/LOAEL
Oral (mg/kg-bw/day)

NOAEL = Not established (54-d)
LOAEL = 10 (54-d)

Reproductive Toxicity
NOAEL/LOAEL
(mg/kg-bw/day)

NOAEL = Not established
LOAEL = 10

Developmental Toxicity
NOAEL/LOAEL
(mg/kg-bw/day)

Maternal Toxicity
Developmental Toxicity

NOAEL = Not established
LOAEL = 10

NOAEL = 10
LOAEL = 100

Genetic Toxicity - Gene Mutation
In vitro

Equivocal

Genetic Toxicity - Chromosomal Aberrations
In vitro

Positive

Genetic Toxicity - Chromosomal Aberrations
In vivo

Negative

— indicates endpoint was not addressed for this chemical.

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