SRC TR-15-024

HPV2 TEST RULE DATA ADEQUACY REVIEW (REVISED FINAL):

MICRONUCLEUS TEST

Phosphorochloridothioic acid, O,O-diethyl ester, CASRN 2524-04-1

Prepared by:

Amy Nguyen, William L. Richards, and Teresa Manyin

Defense and Environmental Solutions Division

SRC, Inc.

7502 Round Pond Road

North Syracuse, NY 13212

Contract No. EP-W-09-027

Task FG007.4.009.001

Submitted to:

OCSPP/OPPT/RAD (7403M)

U.S. Environmental Protection Agency

1200 Pennsylvania Avenue

Washington, D.C. 20460

Bryan Lobar, Project Officer

David Brooks, Work Assignment Manager

Amy Benson, Alternate Work Assignment Manager

March 4, 2015
Final HPV2 Test Rule Data Adequacy Review (March 2015) CASRN 2524-04-1

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TABLE OF CONTENTS

A. SOURCE MATERIAL USED FOR ASSESSMENT .............................................................. 1

B. EVALUATING DATA ADEQUACY ..................................................................................... 1

C. SUMMARY OF DATA ADEQUACY FOR TESTING REQUIRED BY TEST RULE ........ 2

D. DATA FOR SIDS ENDPOINTS.............................................................................................. 3

D-1. Genetic Toxicity – Chromosomal Aberrations.................................................................. 3
Final HPV2 Test Rule Data Adequacy Review (March 2015) CASRN 2524-04-1

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A. SOURCE MATERIAL USED FOR ASSESSMENT

This document evaluates a micronucleus test for CASRN 2524-04-1 (phosphorochloridothioic 

acid, O,O-diethyl ester; O,O-diethyl phosphorochloridothioate [DEPCT]) submitted by Dow 

AgroSciences to EPA in December 2014 in response to the final test rule, “Testing of Certain 

High Production Volume Chemicals; Second Group of Chemicals” (76 FR 1067, January 7, 

2011; referred to herein as HPV2; available online at http://www.regulations.gov/#!document

Detail;D=EPA-HQ-OPPT-2007-0531-0579 as of March 4, 2015). 

The HPV2 test rule requires the following toxicological testing for CASRN 2524-04-1: 

C1 (aquatic toxicity, consisting of Test Group 1 [acute toxicity to fish, acute toxicity to Daphnia, 

and toxicity to algae tests] if log Kow < 4.2 or Test Group 2 [chronic toxicity to Daphnia and 

toxicity to algae tests] if log Kow ≥ 4.2), E1 (bacterial reverse mutation test), E2 (chromosomal 

aberrations or micronucleus test), and F2 (reproduction/developmental toxicity screening test). 

Based on an estimated log Kow of 2.371, Test Group 1 testing is required to determine the toxicity 

of CASRN 2524-04-1 to aquatic organisms.

The December 2014 submission from Dow AgroSciences contained the following study report: 

 Schisler, M.R., and McFadden, L.G. 2014. Evaluation of phosphorochloridothioic acid, 

O,O-diethyl ester (DEPCT) in the mouse peripheral blood micronucleus test. Performing 

Laboratory: The Dow Chemical Company (Toxicology and Environmental Research and 

Consulting), Midland, MI. Sponsor: Dow AgroSciences LLC. Study report available online 

at http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2007-0531-0819 as of 

March 4, 2015.

These newly submitted data are evaluated for adequacy herein. No other toxicity data are 

evaluated in this report. 

B. EVALUATING DATA ADEQUACY

The submitted data are evaluated for adequacy in Section D. The study was summarized 

according to a standard format and assigned a Klimisch reliability code based on its scientific 

merit and conduct, using professional judgment. To determine whether data were adequate to 

satisfy the E2 testing requirement for CASRN 2524-04-1, study details were compared to OECD 

TG 474

2

. In addition, the study was evaluated to determine whether recommendations provided 

 

1 U.S. EPA. 2012. Estimation Programs Interface SuiteTM (EPI Suite) for Microsoft® Windows, v4.11. U.S. 

Environmental Protection Agency, Washington, DC, USA. Available online at http://www.epa.gov/opptintr/

exposure/pubs/episuitedl.htm as of March 4, 2015. 

2 Although the HPV2 test rule specifies that chromosomal aberrations testing should be conducted according to 

TSCA guideline 40 CFR 799.9537, 40 CFR 799.9538, or 40 CFR 799.9539, EPA previously granted a request from 

Dow AgroSciences to follow OECD TG 474 instead (request granted in EPA’s study plan review of CASRN 2524-

04-1, “HPV2 Review of Toxicity Study Plan Dated February 25, 2014: Phosphorochloridothioic acid, O,O-diethyl 

ester, CASRN 2524-04-1”, SRC Technical Report #14-008, dated April 3, 2014; available online at http://www.

regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2007-0531-0805 as of March 4, 2015). 
Final HPV2 Test Rule Data Adequacy Review (March 2015) CASRN 2524-04-1

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in EPA’s study plan review1 were followed. Because CASRN 2524-04-1 has physicochemical

properties (i.e., potential for hydrolysis2and volatilization3) that necessitate special 

considerations in the chromosomal aberrations testing process, EPA had previously provided 

recommendations aimed to minimize loss of the test substance during toxicity testing. 

C. SUMMARY OF DATA ADEQUACY FOR TESTING REQUIRED BY TEST RULE

Evaluation of Data Submitted for the Chromosomal Aberrations Endpoint:

Data submitted by Dow AgroSciences and reviewed in this document are considered adequate to 

satisfy the chromosomal aberrations (E2) testing requirement for CASRN 2524-04-1.

Remaining HPV2 Test Rule Toxicity Testing Requirements:

Dow AgroSciences submitted a study report of a bacterial reverse mutation test of CASRN 2524-

04-1

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, which was reviewed by EPA in a separate report5and determined to be not adequate to 

satisfy the gene mutation (E1) testing requirement for CASRN 2524-04-1 promulgated in the 

HPV2 test rule.

Dow AgroSciences has not yet submitted data for the following toxicity testing requirements for 

CASRN 2524-04-1: acute toxicity to fish (component of C1), acute toxicity to Daphnia

(component of C1), toxicity to algae (component of C1), reproductive toxicity (component of 

F2), and developmental toxicity (component of F2).

Summary of Data Adequacy for Toxicological Endpoints:

Adequate data have been submitted for the chromosomal aberrations endpoint. The acute 

toxicity to fish, acute toxicity to Daphnia, toxicity to algae, gene mutation, reproductive 

toxicity, and developmental toxicity endpoints are considered data gaps and testing is still 

required for these endpoints.

 

1

“HPV2 Review of Toxicity Study Plan Dated February 25, 2014: Phosphorochloridothioic acid, O,O-diethyl ester, 

CASRN 2524-04-1”, SRC Technical Report #14-008, dated April 3, 2014; available online at http://www.

regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2007-0531-0805 as of March 4, 2015.

2 West, R.J., and Hu, J. 2014. Phosphorochloridothioic acid, O,O-diethyl ester: Determination of hydrolysis as a 

function of pH according to OECD Guideline 111. Performing Laboratory: The Dow Chemical Company 

(Toxicology and Environmental Research and Consulting), Midland, MI. Sponsor: Dow AgroSciences LLC. 

3 CASRN 2524-04-1 is considered volatile based on an estimated Henry’s Law Constant of 6.72 x 10-4

atm-m3/mole 

at 25°C (U.S. EPA. 2012. Estimation Programs Interface SuiteTM [EPI Suite] for Microsoft® Windows, v4.11. U.S. 

Environmental Protection Agency, Washington, DC, USA. Available online at http://www.epa.gov/opptintr/

exposure/pubs/episuitedl.htm as of March 4, 2015). 

4 Tendulkar, K.E. 2014. Phosphorochloridothioic acid, O,O-diethyl ester: Salmonella-Escherichia coli mammalianmicrosome reverse mutation assay pre-incubation method with a confirmatory assay. Performing Laboratory: JAI 

Research Foundation, Gujarat, India. Sponsor: Dow AgroSciences LLC.

5

“HPV2 Test Rule Data Adequacy Review: Bacterial Reverse Mutation Test, Phosphorochloridothioic acid, O,Odiethyl ester, CASRN 2524-04-1”, SRC Technical Report #15-023, dated March 4, 2015.
Final HPV2 Test Rule Data Adequacy Review (March 2015) CASRN 2524-04-1

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D. DATA FOR SIDS ENDPOINTS

D-1. Genetic Toxicity – Chromosomal Aberrations

Summary of endpoint: Adequate 

Study 1: In vivo mouse micronucleus assay (Schisler and McFadden, 2014)

Title: Evaluation of phosphorochloridothioic acid, O,O-diethyl ester (DEPCT) in the mouse 

peripheral blood micronucleus test

This study is: Adequate Not Adequate

TEST SUBSTANCE 

Identity: Phosphorochloridothioic acid, O,O-diethyl ester (DEPCT), CASRN 2524-04-1

 

Remarks: Purity: 99.3%; Lot No. C032013081501

METHOD

Method/guideline followed: OECD TG 474 (1997; “Mammalian Erythrocyte Micronucleus 

Test”), Method B.12 of Commission Regulation (EC) No. 440/2008 (2008; “Mutagenicity – In 

vivo Mammalian Erythrocyte Micronucleus Test”), and OPPTS 870.5395 (1998; “Mammalian 

Erythrocyte Micronucleus Test”)

Test type: In vivo Mouse Micronucleus Assay

GLP compliant?: Yes, with the following exception: “A concentration check or stability for the 

positive control substance (cyclophosphamide monohydrate) used in this study were not 

performed; however, the responsiveness of the animals to the control substance met expectations, 

therefore this exception had no impact on the study.” [Schisler and McFadden 2014, p. 2]

Year study performed: 2014

Test species: Crl:CD1(ICR) male mice; obtained from Charles River, Kingston, NY; at 

initiation, the animals were approximately 8 to 10 weeks old and weighed 31.6 to 35.5 grams

(body weights of animals on day 1 of the micronucleus test).

Metabolic activation: Not applicable

Number of animals/sex/dose: 6 males/dose (0, 75, and 150 mg/kg-bw/day); 8 males/dose (300 

mg/kg-bw/day)

Route of administration: Oral (gavage)
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Vehicle: Corn oil (non-anhydrous)1

Doses/concentrations tested: 0 (vehicle only), 75, 150, and 300 mg/kg-bw/day

Statistical methods used: Micronucleated reticulocytes (MN-RET) and percent reticulocytes 

(RET) were tested for equality of variance with Bartlett’s test (alpha = 0.01). MN-RET data 

were log transformed for comparison of the positive control to the negative control. 

“Based on the similarity of the response between sexes in the RFT [range-finding test], the MNRET data and the data on percent RET were analyzed by a one-way analysis of variance (only 

males were used)... The alpha level at which all tests were conducted was 0.05.” [Schisler and 

McFadden 2014, p. 16]

“The MN-NCE [micronucleated normochromatic erythrocytes] was not analyzed statistically and 

was only used as an adjunct end point to evaluate the biological significance of the MN-RET 

results.” [Schisler and McFadden 2014, p. 16]

Test method/conditions remarks: Dosing formulations of the test substance in corn oil were 

prepared fresh for each consecutive day of dosing. 

Concentration and Homogeneity of Dosing Formulations in the Micronucleus Test:

Test concentrations and homogeneity were determined in the micronucleus test for dosing 

formulations prepared on the first of two consecutive days of dosing using gas chromatography 

with electron capture detection (GC/ECD). Test concentrations were determined in each dosing 

formulation (i.e., control, low-, intermediate-, and high-dose levels) based on two or three 

samples collected from each dosing formulation container. Homogeneity was evaluated for the 

low- and high-dose levels based on samples collected from three different positions (top, middle, 

and bottom) of each dosing formulation container. Samples for concentration and homogeneity 

determination were collected with a wide-orifice pipet tip while the dosing formulations were

being stirred.

Animal Housing and Environmental Conditions:

Prior to the start of the study, the animals were acclimated to the laboratory conditions for at 

least one week. During the study, animals were housed one per cage in stainless steel cages. 

The animal room was maintained at 22 ± 1°C and 40-70% humidity, with 12-15 air changes per 

hour (average) and a 12-hour light/dark photoperiod. 

Range-Finding Test Procedure: 

A dose range-finding test was conducted in male and female mice to determine suitable dose 

levels for the micronucleus test. On the first day of dosing, males weighed 29.1 to 36.5 grams 

and females weighed 22.9 to 30.2 grams. Groups of mice were administered the test item as 

either a single dose (1/sex/dose at 1000 and 2000 mg/kg-bw) or a single dose on each of two 

 

1 Although the corn oil vehicle was not fully described in the study report, Dow AgroSciences indicated in a 

submission to EPA on February 16, 2015 (email from Dr. George Oliver of Dow AgroSciences to Mr. John 

Schaeffer of EPA) that the corn oil used as a vehicle was non-anhydrous. 
Final HPV2 Test Rule Data Adequacy Review (March 2015) CASRN 2524-04-1

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consecutive days (3/sex/dose at 250 and 375 mg/kg-bw/day; 3 males and 1 female at 500 mg/kgbw/day). Doses were administered at a constant dosing volume of 10 mL/kg-bw. 

All treated animals were observed for mortalities. Surviving animals were observed daily for 

signs of toxicity until the day of scheduled sacrifice (day 4). Body weights were determined on 

the day of dosing and on the day of scheduled sacrifice. “The relative body temperatures of the 

treated animals were monitored during the RFT [range-finding test] using programmable 

transponders... The temperatures were generally collected by scanning the microchip prior to 

each dosing, and approximately 2, 5, and 24 hours after dosing as well as prior to sacrifice.” 

[Schisler and McFadden 2014, p. 14]

“All mortalities and/or moribund animals were necropsied to ascertain whether the condition was 

related to a dosing mishap.” [Schisler and McFadden 2014, p. 11]

Micronucleus Test Procedure: 

Male mice received a single dose of the test item on each of two consecutive days via gavage at 

75, 150, or 300 mg/kg-bw/day at a constant dosing volume of 10 mL/kg-bw. Groups of 6

animals were dosed at 75 and 150 mg/kg-bw/day and 8 animals were dosed at 300 mg/kgbw/day.

1

 A negative control group of 6 animals was similarly administered a single dose of the 

vehicle (corn oil) on two consecutive days. A positive control group of 6 animals was 

administered a single dose of cyclophosphamide monohydrate at 40 mg/kg-bw by gavage. 

Mortalities were recorded and the mice were observed daily for other signs of toxicity. Animal 

body weights were recorded prior to dosing and on the day of scheduled sacrifice (day 4). 

Peripheral blood samples were collected from all animals approximately 48 hours after the 

second dose of the test item (and 48 hours after the single dose of the positive control substance).

“Temperatures were monitored during the main study since a decrease of at least 3°C for more 

than 5 hours was observed during the RFT [range-finding test]. Body temperature changes 

outside this range have been previously reported to cause an increase in micronucleus 

formation.” [Schisler and McFadden 2014, p. 14]

Evaluation of Micronuclei Formation:

Approximately 5000 reticulocytes per animal (6/dose)2 were analyzed by flow cytometry for 

micronuclei formation. “Samples were prepared and analyzed per instructions in the Mouse 

MicroFlow Micronucleus Analysis Kit Manual... At the end of the specified interval following 

treatment, a peripheral blood sample was collected from the orbital sinus of all surviving animals 

into anticoagulant solution following anesthesia with isoflurane. Briefly, the blood samples were 

fixed in ultracold (-70 to -80°C) methanol within five hours of collection. All fixed blood 

samples were stored at -80°C. Fixed blood samples of the first six mice of each group were 

washed with a cold, buffered salt solution and isolated by centrifugation. The resulting cell 

pellets were stored at approximately 4°C until staining. Blood samples were ultimately 

incubated with RNase to degrade the high levels of RNA present in the reticulocytes (RET) and a 

fluorescently labeled antibody to the transferrin receptor (anti-CD71-FITC) to specifically 

 

1 Two additional mice were dosed at 300 mg/kg-bw/day to provide possible replacements in the event of mortality in 

this group.

2 Reticulocytes from only 6 (out of 8 total) mice dosed at 300 mg/kg-bw/day were analyzed.
Final HPV2 Test Rule Data Adequacy Review (March 2015) CASRN 2524-04-1

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identify the RET. A propidium iodide solution was added to each sample immediately before 

flow cytometry (FCM)... analysis to stain the DNA, including that of micronuclei. Blood 

samples were analyzed by high-speed FCM. In this system, the sample was moved at a high 

velocity past a laser set to provide 488 nm excitation. The fluorescent wavelengths emitted by 

each cell were collected by photomultiplier tubes. Using the previously described staining 

procedure, the propidium iodide-stained DNA of the micronuclei emitted a red fluorescence and 

the anti-CD71-FITC antibody emitted a high green fluorescent signal permitting differentiation 

between cells with and without micronuclei. In addition to obtaining fluorescent profiles, FCM 

simultaneously provided cell size information by determining the light scatter properties of each 

cell or combination of cells.” [Schisler and McFadden 2014, pp. 14-15]

“The number of normochromatic erythrocytes (NCE), MN [micronucleated]-NCE, RET, and 

MN-RET were recorded for each sample and the frequency of MN-RET was determined to 

provide an indication of genotoxic potential. The frequency of RETs relative to total 

erythrocytes [results reported as “% RET” in Tables 12 and 13 of the study report] was 

determined to provide an indication of perturbations in hematopoietic activity indicative of cell

toxicity. For each of the treatment groups, a mean and standard deviation was calculated to 

describe the frequency of RET, MN-NCE, and MN-RET observed.” [Schisler and McFadden 

2014, p. 15]

Slide Preparation: 

“Duplicate cell smears were prepared and stored to serve as backups in the event that the flow 

cytometric analysis was not possible. Blood was collected into a microtainer tube coated with 

EDTA. Wedge smears were prepared, fixed in methanol, and stored at room temperature.” 

[Schisler and McFadden 2014, p. 15]

Criteria for Determination of a Response: 

The test material was considered positive in this assay if the following criterion was met: 

“Statistically significant increase in MN-RET frequency at one or more dose levels accompanied 

by a dose response.” [Schisler and McFadden 2014, p. 16]

The test material was considered negative in this assay if the following criterion was met: 

“No statistically significant dose-related increase in MN-RET when compared to the negative 

control.” [Schisler and McFadden 2014, p. 16]

“A test result not meeting the criteria for either the positive or the negative response was 

considered to be equivocal.” [Schisler and McFadden 2014, p. 16]

Criteria for a Valid Test:

The test was considered valid if the following conditions were met:

 “The range of MN-RET values in the negative controls were within reasonable limits of the 

recent laboratory background range.

 There was a significant increase in the incidence of MN-RET in the positive control 

treatment as compared to the concurrent negative controls.
Final HPV2 Test Rule Data Adequacy Review (March 2015) CASRN 2524-04-1

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 The mean for percent RET value in one or more of the test material treated groups was 

≥ 20% of the control value indicating no undue effect on erythropoiesis (toxicity).” [Schisler 

and McFadden 2014, pp. 15-16]

RESULTS

Genotoxicity result: Negative 

Toxic concentration (if applicable): ≥ 300 mg/kg-bw/day (based on clinical signs of toxicity 

observed in 6/8 animals)

Results remarks: The analytically determined mean measured concentrations of test item in the 

dosing formulations prepared on the first day of dosing in the micronucleus test ranged from 

90.7% to 92.4% of nominal concentrations1. The dosing formulations prepared on the first day 

of dosing in the micronucleus test were homogenous, based on a relative standard deviation 

(RSD) of 1.8% and 4.8% for the low- and high-dose formulations, respectively. 

Range-Finding Test Results: 

Mortalities occurred in the male administered a single dose of the test item at 1000 mg/kg-bw 

and in both animals (1/sex) administered a single dose of the test item at 2000 mg/kg-bw. These 

3 animals died within 5 hours following dosing. The female dosed with 1000 mg/kg-bw was 

found in a moribund condition at the 5-hour observation and was sacrificed. Clinical signs of 

toxicity observed in one or more animals at 1000 or 2000 mg/kg-bw included labored respiration 

with mouth breathing, incoordinated gait, no or decreased activity, no reactivity, reduced body 

temperature, bluish skin and mucous membranes, cold to the touch, clear perioral soiling, fecal 

perineal soiling, and soft feces. Examination of animals dosed with 2000 mg/kg-bw by a 

pathologist revealed “watery contents in the intestines and hemolyzed blood in the stomach with 

no evidence of a dosing error.” [Schisler and McFadden 2014, p. 17] The study report did not 

indicate whether similar abnormalities were observed at necropsy in the intestines and stomach 

of animals dosed with 1000 mg/kg-bw.

Although no spontaneous mortalities occurred in the animals administered a dose of 500 mg/kgbw/day on two consecutive days, the female and two of the three males administered 500 mg/kgbw/day were found in a moribund condition on the second day of dosing (after the second dose 

was administered) and were sacrificed. Although no evidence of gavage error was found at 

necropsy in any of these animals sacrificed prior to scheduled sacrifice, one male had small 

 

1 Given that the test item is susceptible to hydrolysis and volatilization, EPA recommended in its review of the 

protocol submitted for the proposed micronucleus test of CASRN 2524-04-1 that the vehicle be anhydrous and that 

precautions (e.g., airtight seals, minimal headspace, and minimal exposure to air) be taken to minimize volatilization 

during preparation and handling of dosing formulations. Although the corn oil vehicle was non-anhydrous, and the 

study report does not specify whether or not precautions were taken to minimize volatilization, EPA considers 

concerns regarding hydrolysis and volatilization of the test substance in corn oil during the test to be negligible for 

the following reasons: (a) The mean measured concentrations of the dosing formulations in this micronucleus test 

were within an acceptable range (measured concentrations on the first day of dosing were 90.7 to 92.4% of nominal 

concentrations); and (b) Two stability tests (Perala and McFadden, 2014; Andrus et al., 2014) submitted to EPA by 

Dow AgroSciences on February 23, 2015 (as attachments in an email from Dr. George Oliver of Dow AgroSciences 

to Mr. John Schaeffer of EPA) demonstrated that CASRN 2524-04-1 was stable in non-anhydrous corn oil for up to 

24 days.
Final HPV2 Test Rule Data Adequacy Review (March 2015) CASRN 2524-04-1

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ulcers in the glandular mucosa and hemolyzed blood in the lumen of the stomach. Clinical signs 

of toxicity observed at 500 mg/kg-bw/day included continuous muscle tremor, muscle tremor 

associated with movement or stimuli, reduced body temperature, cold to the touch, urine perineal 

soiling, fecal perineal soiling, watery and/or soft feces, decreased quantity of feces, decreased 

activity, and partially closed eyelids (bilateral).

Of the animals (3/sex/dose) administered 375 mg/kg-bw/day on two consecutive days, one 

female was found dead on the day following the second dose. Examination of this animal by a 

pathologist revealed no evidence of a gavage error. No other animals died or were sacrificed 

moribund at this dose level. Clinical signs of toxicity observed at 375 mg/kg-bw/day included 

slight muscle tremor, muscle tremor associated with movement or stimuli, decreased activity, 

reduced body temperature, cold to the touch, fecal perineal soiling, watery and/or soft feces, and 

decreased quantity of feces or absent feces. 

No mortalities occurred in animals administered 250 mg/kg-bw/day on two consecutive days. 

Clinical signs of toxicity observed at 250 mg/kg-bw/day were limited to perineal fecal soiling 

and watery feces in one female. 

Since there were no appreciable differences in toxicity between males and females during the 

range-finding test, the micronucleus test was performed in male mice only. 

Micronucleus Test Results: 

No mortalities occurred in the micronucleus test. No treatment-related changes in body weight 

or body temperature were observed. One of six negative control animals exhibited urine perineal 

soiling and decreased feces. No clinical signs of toxicity were observed in animals dosed with 

75 mg/kg-bw/day. At 150 mg/kg-bw/day, clinical signs were limited to soft feces in 1/6 animals. 

Clinical signs of toxicity were observed in 6/8 animals at 300 mg/kg-bw/day and included soft 

feces, decreased quantity of feces, urine perineal soiling, and fecal perineal soiling.

“There were no significant differences in MN-RET frequencies between the groups treated with 

the test material and the negative controls. The adequacy of the experimental conditions for the 

detection of induced micronuclei was ascertained from the observation of a [statistically] 

significant [p < 0.05] increase in the frequencies of micronucleated RET in the positive control 

group...” [Schisler and McFadden 2014, p. 21]

“The percent RET values observed in the test material-treated animals were not significantly 

different from the negative control values... The percent RET values of the positive control 

animals were found to be [statistically] significantly [p < 0.05] lower than those of the negative 

control animals.” [Schisler and McFadden 2014, p. 21]

CONCLUSIONS

The test item did not induce micronuclei in peripheral blood reticulocytes in male mice 

administered the test item on two consecutive days at dose levels of 75, 150, and 300 mg/kgbw/day. 
Final HPV2 Test Rule Data Adequacy Review (March 2015) CASRN 2524-04-1

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STUDY RELIABILITY

[1] Reliable without restrictions. 

REFERENCES

Andrus, A.K., Zablotny, C.L., Hannas, B.R., and Sura, R. 2014. Phosphorochloridothioic acid, 

O,O-diethyl ester: 14-day oral gavage range-finding study in Crl:CD(SD) rats. Performing 

Laboratory: The Dow Chemical Company (Toxicology and Environmental Research and 

Consulting), Midland, MI. Sponsor: Dow AgroSciences LLC.

Perala, A.W., and McFadden, J.R. 2014. Phosphorochloridothioic acid, O,O-diethyl ester: 

Method validation and stability in rodent feed, corn oil, and toluene. Performing Laboratory: 

The Dow Chemical Company (Toxicology and Environmental Research and Consulting), 

Midland, MI. Sponsor: Dow AgroSciences LLC.

Schisler, M.R., and McFadden, L.G. 2014. Evaluation of phosphorochloridothioic acid, O,Odiethyl ester (DEPCT) in the mouse peripheral blood micronucleus test. Performing Laboratory: 

The Dow Chemical Company (Toxicology and Environmental Research and Consulting), 

Midland, MI. Sponsor: Dow AgroSciences LLC. Study report available online at http://www.

regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2007-0531-0819 as of March 4, 2015.

Text in quotes is taken directly from Schisler and McFadden (2014).