				SRC TR-12-033

HPV3 TOXICITY TEST PLAN REVIEW (DRAFT)

Propanoic acid, 2-methyl-, 3-(benzoyloxy)-2,2,4-trimethylpentyl ester,
CASRN 22527-63-5

Prepared by:

William L. Richards, Teresa Manyin, and Laura Morlacci

Chemical, Biological and Environmental Center

SRC, Inc.

7502 Round Pond Road

North Syracuse, NY 13212

Contract No. EP-W-09-027

Task FG007.2.009.006

Submitted to:

OCSPP/OPPT/RAD (7403M)

U.S. Environmental Protection Agency

1200 Pennsylvania Avenue

Washington, D.C. 20460

Debra Milligan, Project Officer

Meena Sonawane, Work Assignment Manager

David Brooks, Alternate Work Assignment Manager

March 9, 2012

HPV3 Toxicity Test Plan Review

Propanoic acid, 2-methyl-, 3-(benzoyloxy)-2,2,4-trimethylpentyl ester,
CASRN 22527-63-5

The test rule, “Testing of Certain High Production Volume Chemicals;
Third Group of Chemicals” (76 FR 65385, October 21, 2011), requires
the following toxicity testing for propanoic acid, 2-methyl-,
3-(benzoyloxy)-2,2,4-trimethylpentyl ester, CASRN 22527-63-5: C1
(aquatic toxicity), D (mammalian toxicity – acute), E1 (bacterial
reverse mutation test), E2 (chromosomal aberration or micronucleus test)
and F1 (mammalian toxicity – repeated
dose/reproduction/developmental).  Eastman Chemical Company (Eastman)
submitted a test plan on February 20, 2011 to address the endpoints
required by the test rule.  The adequacy of the test plan is evaluated
below.

1.  General Comments:

The test rule classifies propanoic acid, 2-methyl-,
3-(benzoyloxy)-2,2,4-trimethylpentyl ester, CASRN 22527-63-5 as a Class
1 Chemical Substance for which testing must be conducted with material
having a purity of 99% or greater.  However, for toxicity testing,
Eastman proposes the use of a bulk reaction product of the following
purity: 60-65% propanoic acid, 2-methyl-,
3-(benzoyloxy)-2,2,4-trimethylpentyl ester (CASRN 22527-63-5), 20-25%
1,3-pentanediol, 2,2,4-trimethyl-1,3-dibenzoate (CASRN 68052-23-3), and
10-15% 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (CASRN 6846-50-0). 
EPA approves Eastman’s plan to conduct aquatic and mammalian toxicity
tests of this mixture (“the bulk reaction product”) based on the
following: 

(1) Eastman states that “The manufacture of benzoate ester for
commercial use has been as a bulk reaction and there is no readily
available process to synthesize the chemical substance by direct
reaction to achieve the purity required for Class 1 substances.  Eastman
believes that use of the bulk reaction product which is formulated into
finished products for commercial sale will more accurately represent
exposure and use of the benzoate ester and avoid a costly and
technically uncertain purification procedure.”

(2) In commerce, the bulk reaction product that is formed through an
esterification reaction between benzoic acid (CASRN 65-85-0) and
2,2,4-trimethyl-1,3-pentanediol diisobutyrate (CASRN 6846-50-0) results
in three chemicals (CASRNs 22527-63-5, 68052-23-3, and 6846-50-0). 
These chemicals, the diesters of 2,2,4-trimethyl-1,3-pentanediol with
benzoic acid and 2-methylpropanoic acid (isobutyric acid), can be
considered close analogs. 

(3) The major constituent of the bulk reaction product is the test rule
substance, propanoic acid, 2-methyl-,
3-(benzoyloxy)-2,2,4-trimethylpentyl ester, CASRN 22527-63-5.

For all toxicity tests, the final study report should include the
analyzed composition of the test substance, including identities and
concentrations of major ingredients and of impurities.  

2.  Aquatic Toxicity

 ≥ 4.2 or an Acute Toxicity to Daphnia test using ASTM E 729-96
(Reapproved 2007) if the measured log Kow is < 4.2.  

In addition to daphnid testing, the following studies of the bulk
reaction product must be conducted to fulfill testing requirement C1 of
the test rule:  Toxicity to Plants (Algae) using ASTM E 1218-04
(required for all chemicals regardless of log Kow value); and Acute
Toxicity to Fish using ASTM E 729-96 (Reapproved 2007) if the measured
log Kow is < 4.2.  Note that Eastman failed to include these required
tests in the submitted test plan.

3.  Mammalian Toxicity – Acute

EPA approves Eastman’s plan to conduct an Acute Oral Toxicity –
Up-and-Down Procedure test of the bulk reaction product using OECD TG
425 to fulfill testing requirement D.

4.  Bacterial Reverse Mutation Test

EPA approves Eastman’s plan to conduct a Bacterial Reverse Mutation
Test using 40 CFR 799.9510 of the bulk reaction product to fulfill
testing requirement E1.

5.  Chromosomal Aberration/Micronucleus Test

EPA approves Eastman’s plan to conduct an In vitro Mammalian
Chromosomal Aberration Test of the bulk reaction product using 40 CFR
799.9537 to fulfill testing requirement E2.

6.  Mammalian Toxicity – Repeated Dose/Reproduction/Developmental

For the following reasons, EPA does not approve Eastman’s request to
fulfill testing requirement F1 “through the use of data already
available on the three primary metabolites of the test substance: 
namely benzoic acid, 2,2,4-trimethyl-1,3-pentanediol (TMPD) and
isobutyrate.”:  

(1) For the diesters of 2,2,4-trimethyl-1,3-pentanediol (CASRNs
22527-63-5, 68052-23-3 and  6846-50-0) that are present in the bulk
reaction product that Eastman proposes for testing for the
physical/chemical properties, environmental fate, aquatic toxicity,
acute mammalian toxicity and genotoxicity endpoints, Eastman has not
provided data to show that non-enzymatic or enzymatic hydrolysis of
these esters will occur fast enough to justify testing of only the
presumptive hydrolysis products/metabolites for addressing the mammalian
repeated-dose, reproductive, and developmental toxicity endpoints.  
Eastman cites an oral gavage study of diethyleneglycol dibenzoate, which
showed “that the ester linkages are completely hydrolyzed with no
evidence of parent compound in the urine”.  However, the rate and
extent of non-enzymatic or enzymatic hydrolysis of the three diesters
present in Eastman’s bulk reaction product (CASRNs 22527-63-5,
68052-23-3 and 6846-50-0) may be inhibited compared with
diethyleneglycol dibenzoate because of greater steric hindrance by the
branched 2,2,4-trimethylpentyl moiety than by the diethylene glycol
moiety.

(2) Eastman does not present a rationale to show that data from separate
repeated-dose, reproductive, and developmental toxicity studies of
individual hydrolysis products/metabolites of the bulk reaction product
would be adequate to characterize toxicity of the mixture of these
substances expected to occur in vivo.  Although data for the individual
hydrolysis products/metabolites are useful to address the overall
toxicity of the bulk reaction product, the data for these individual
hydrolysis products/metabolites would not address the potential for
interactions (e.g., additivity, synergism or antagonism) among these
degradatation products, mono-ester intermediates, and the residual
diesters of the bulk reaction product.  The likelihood for such
interactions could vary with exposure route since the acidic environment
of the stomach during oral exposure could result in higher rates of
nonenzymatic ester hydrolysis than for exposures by the inhalation or
dermal routes.

Based on the preceding discussion, testing requirement F1 should be
fulfilled by conducting a Combined Repeated Dose Toxicity Study with the
Reproduction/Developmental Toxicity Screening Test (40 CFR 799.9365) of
the bulk reaction product; OR the Reproduction/Developmental Toxicity
Screening Test (40 CFR 799.9355) AND the Repeated Dose 28-Day Oral
Toxicity Study in Rodents Test (40 CFR 799.9305) of the bulk reaction
product.

Conclusion:  The submitted test plan for toxicity testing is adequate to
satisfy test rule requirements C1, D, E1, E2, and F1 with the exceptions
and stipulations listed above.  

Final HPV3 Toxicity Test Plan Review		CASRN 22527-63-5

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