...\.~EO Sl'-4~ .~~ ~c$\. 

~ U UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

S m WASHINGTON D.C., 20460 

:xJ C) <i 'If 

~ ~ 

~ f\~ ~i. PRO'1~(i 

MEMORANDUM 

SUBJECT: 

FROM: 

THRU: 

TO: 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

March 16,2012 

Product Chemistry, Environmental Fate, and Ecological Effects Scoping 

Document in Support of Registration Review of Methyloxazolidines 

PC Codes: DP Barcode: 394305 

4,4-dimethyloxazolidine: 114801 

3,4,4-Trimethyloxazolidine: 114802 

Decision No.: 455124 Registration Nos.: See Appendix A Table 1 

Petition No(s).: NA Regulatory Action: Ecological 

Environmental Scoping Document for 

Registration Review 

Risk Assessment Type: Multiple Case No.: 3095 

chemicals 

TXRNo.:NA CAS Nos.: 

4,4-Dimethyloxazolidine: 51200-87-4; 

and 

3,4,4-TrimethyJoxazolidine: 75673-43-7 

MRID No.: See Tables 1,2, 3 and 4 & 40 CFR: None 

pg.nos. 8,9,10,11,12,13,14,15, 

18, 19,20 

Srinivas Gowda, Microbiologist/Science Coord ~~ ~~~ o..5t ~Q.. James Breithaupt, Agronomist y~,~-, -- Zoe Layton, Biologist ~ Risk Assessment and Sc· c u ort Branch (RASSB) 

Antimicrobials Division P) 

Nader 

Donna 

Elkassabany, 

Randall, Ecological 

PhD, Branch 

Risk Assessment 

Chief vfla.b 

Team Lead 

~ ~I ~ Risk Assessment and Science Support Branch (RASSB) --l 

Antimicrobials Division (751OP) 

Mark Hartman, Branch Chief 

Lance Wormell, Team Leader 

Seiichi Murasaki, Chemical Review Manager 

Regulatory Management Branch II 

Antimicrobials Division (751 OP) 

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(This page is intentionally left blank.)
Page 3 of 40

Contents

Executive Summary........................................................................................................................ 4

1. Introduction ............................................................................................................................. 7

2. Product Chemistry Summary .................................................................................................. 7

3. Environmental Fate Summary................................................................................................. 8

4. Water Quality Summary........................................................................................................ 10

5. Ecological Effects Summary ................................................................................................. 10

5.1. Toxicity to Birds, Acute and Subacute........................................................................... 10

5.2. Toxicity to Freshwater Aquatic Animals........................................................................ 12

5.3. Toxicity to Estuarine and Marine Animals..................................................................... 14

5.4. Toxicity to Aquatic Plants.............................................................................................. 15

5.5. Toxicity of Degradation Products................................................................................... 15

5.5.1.1. Toxicity to Avian Species.................................................................................... 15

5.5.1.2. Toxicity to Freshwater Fish and Invertebrates..................................................... 16

5.5.1.3. Toxicity to Estuarine/Marine Fish and Invertebrates........................................... 17

5.5.1.4. Toxicity to Aquatic Plants ................................................................................... 18

6. Facility Emissions to WWTP Modeling................................................................................ 20

7. Environmental Fate and Ecotoxicity Data Gaps and Anticipated Work............................... 22

TABLE 1. Ecotoxicity Data Summary for DMO......................................................................................................11

TABLE 2. Ecotoxicity Data Summary for EP (BiobanTM CS-1135)........................................................................12

TABLE 3. Ecotoxicity Data Summary for AMP.......................................................................................................16

TABLE 4. Ecotoxicity Data Summary for Formaldehyde ........................................................................................18
Page 4 of 40

Executive Summary

Methyloxazolidines, case 3095, consists of two active ingredients 4,4-dimethyloxazolidine 

(DMO) (PC Code 114801) and 3,4,4-trimethyloxazolidine (PC Code 114802). However, one of 

these active ingredients—3,4,4-trimethyloxazolidine, does not currently have any registered 

products. Because this active ingredient is not being supported it is not addressed in this 

registration review; during this time if a registrant were to seek a registration of an end-use 

product with this active it would require a new use active ingredient assessment. DMO is the 

only active ingredient reviewed in the methyloxazolidines registration review case.

DMO is a water soluble, liquid organic biocide, registered for use as a material preservative 

for the protection of caulks, sealants, grouts, spackling, ready-mixed wallboard compounds, 

water-based resin emulsions, metalworking cutting fluids, latex paints, adhesives, inks, 

dispersed colors and ready-mixed joint cements against microbial deterioration and as a 

microbiocide and bacteriostat additive in laundry detergents and cleansers, industrial process 

water systems, secondary oil recovery injection water and oil recovery drill muds. DMO 

was first registered in the United States in October 1982 for use as an industrial preservative 

for metalworking fluids, latex paints and resin emulsions. A Reregistration Eligibility 

Decision (RED) for 4,4-Dimethyloxazolidine was completed in August 1996. Hazards were 

characterized as part of the assessment but no quantitative risk assessment was performed. 

To address these hazards labels for DMO products require that discharges to aquatic 

environments comply with a National Pollutant Discharge Elimination System (NPDES) 

permit and wastes be disposed of appropriately. Currently there are three companies with a 

total of six products—all are end-use products. All product chemistry data requirements 

have been satisfied for this active ingredient.

As part of the registration review process, risk assessments for those DMO use patterns 

resulting in discharge of DMO and its major degradates of concern to water will be 

conducted. DMO degrades rapidly by hydrolysis in minutes to form 2-amino-2-methyl-1-

propanol (AMP, CAS No. 124-68-5), which is stable to abiotic degradation processes. 

Because DMO is hydrolyzed so rapidly to AMP and formaldehyde, photodegradation of 

DMO in water is not a significant route of degradation. The Agency's in-house database 

does not have any acceptable environmental fate and transport data on the degradate, AMP. 

These data are required to assess environmental fate for the registered use patterns that may 

potentially enter waste water treatment plants (WWTPs) and subsequently be discharged to 

aquatic environments. 

AMP is on the 2007 Organization for Economic Co-operation and Development (OECD) 

list of high production volume (HPV) chemicals1 for which a Screening Information Data 

Set (SIDS) Initial Assessment Report was scheduled to be performed. As part of this effort 

a Robust Summary of data2

 1 The 2007 OECD List of High Production Volume Chemicals, Series on Testing and Assessment, Number 112,23 

October 2009

has been submitted to the Agency. The letter submitted with the 

Robust Summary contained a request from Dow for AMP to be removed from the 

2 letter dated 8/28/2011 from The Dow Chemical Company to Mark Townsend, Chief, HPV Chemicals Branch of 

EPA/OCSPP/OPPT
Page 5 of 40

International Council of Chemical Associations (ICCA) Program and brought back to the 

EPA HPV Challenge Program.

An examination of the chemical structure and a review of information in this Robust 

Summary for AMP, indicates that a high percentage of AMP may be removed by 

conventional sewage treatment systems. Specifically, the biodegradation of AMP has been 

demonstrated in a laboratory ready biodegradability study to remove 89% of the 

biochemical oxygen demand (BOD) in 28 days under aerobic conditions, using non-adapted 

domestic activated sludge inoculum (OECD Guideline test 301F). The primary removal 

mechanism was attributed to mineralization.

To be able to give merit to this claim, the Agency needs to review and evaluate the primary 

references cited in this letter to the Agency. Without reviewing and evaluating these primary 

references and reaching the same conclusions as those presented, the Agency anticipates needing 

environmental fate data from tests:

• Activated Sludge Sorption Isotherm (GLN 835.1110);

• Anaerobic aquatic metabolism for the degradate AMP (GLN 835.440);

• Aerobic aquatic metabolism for the degradate AMP (GLN 835.4300);

• Ready biodegradability (GLN 835.3110), or Porous Pot Test (GLN 835.3220), or

Simulation Tests to Assess the Biodegradability of Chemicals Discharged to Wastewater

(GLN 835.3280), or Simulation Test – Aerobic Sewage Treatment: A. Activated Sludge 

Units(GLN 835.3240) for AMP.

With the exception of one avian oral toxicity study on a waterfowl species (OCSPP Guideline 

850.2100), the ecotoxicological database is adequate to characterize the hazards from acute 

toxicity of DMO to nontarget terrestrial and aquatic organisms. However, there is a lack of data 

for assessing risk from the major degradate, AMP, which is the form exposure will occur for 

nontarget organisms. The Agency anticipates needing the following ecotoxicity data in order to 

conduct a complete ecological risk assessment, including an endangered species determination: 

o Activated Sludge Respiration Inhibition for AMP (GLN 850.6800 or OECD 209);

o Avian acute oral toxicity test, using the bobwhite quail for AMP (OCSPP 

850.2100);

o Freshwater fish acute toxicity, most a.i. sensitive species the bluegill sunfish—

major degradation product, AMP (OCSPP 850.1075);

o Fish early-life stage toxicity test, freshwater species with the same species acute 

toxicity is conducted on (bluegill sunfish)—major degradation product, AMP 

(OCSPP 850.1400);

o Freshwater invertebrate acute toxicity, Daphnia magna—major degradation 

product, AMP (OCSPP 850.1010);

o Aquatic invertebrate life-cycle, freshwater Daphnia magna— major degradation 

product, AMP (OCSPP 850.1300);

o Estuarine/marine fish acute toxicity study—major degradation product, AMP 

(OCSPP 850.1075);

o Estuarine/marine invertebrate acute toxicity using the saltwater mysid— major 

degradation product, AMP (OCSPP 850.1035);
Page 6 of 40

o Mollusk embyro larvae or shell deposition study— major degradation product, 

AMP (OCSPP 850.1055 or 850.1025);

o Aquatic invertebrate life-cycle, saltwater Americamysis bahia— major 

degradation product, AMP (OCSPP 850.1350);

o Seedling emergence (Tier II) with rice— major degradation product, AMP 

(OCSPP 850.4225);

o Aquatic plant toxicity test using Lemna spp.— major degradation product, AMP 

(OCSPP 850.4400);

o Algal toxicity (Tier II) for four species— major degradation product, AMP 

(OCSPP 850.5400).
Page 7 of 40

1. Introduction

4,4-Dimethyloxazolidine (DMO) was initially registered as a pesticide in the United States in 

October 1982 for use as a microbiocide and bacteriostat industrial preservative for metalworking 

fluids, latex paints and resin emulsions. Currently it is used in six products (Appendix A Table 

1). It is used as a materials preservative in such products as caulks, sealants, grouts, spackling, 

ready-mixed wallboard compounds, resin emulsions, latex paints, adhesives, inks, resin 

emulsions, dispersed colors, ready-mixed joint cements, metalworking cutting fluids, lubricants 

and mold release agents in plastic manufacturing, mineral slurries, dishwashing liquids, surface 

cleaners, laundry cleaners, polishes, home care cleaning products including floor cleaners,

waxes, polishes and surface cleaners; laundry additives including liquid laundry detergents, 

fabric softeners, and stain removers. It is also used in industrial processes and water systems 

such as gas/oil recovery injection systems, non-marine enhanced oil recovery systems, oil field 

water systems, metal working fluids, preserving drilling muds, workover and completion fluids, 

polymer of micellar floods, water-disposal systems or other oil field water systems (Appendix A 

Tables 2 and 3). A Reregistration Eligibility Decision (RED) was issued by EPA for DMO in 

August 19963

.

There are two active ingredients in the Methyloxazolidines case 3095; however, one of these 

active ingredients, 3,4,4-Trimethyloxazolidine (PC Code 114802), does not have registered 

products. This chemical is not being supported and is not addressed in this registration review. 

DMO is the only active ingredients in the case with active products.

The Agency has conducted a review of the available product chemistry, environmental fate, and 

ecotoxicity data for DMO. The primary source of information for this assessment was the 1996

DMO RED. The findings are summarized below.

2. Product Chemistry Summary of DMO (78% Liquid)

Common Name: 4,4-Dimethyloxazolidine (DMO)

Chemical Name: 4,4 - Dimethyloxazolidine

OPP Chemical Code: 114801

CAS Registry Number: 51200-87-4

Trade Names: Bioban CS-1135; Nuosept 101; Cosan 101;Troysan 192 

Molecular Formula: C5H11NO

Molecular weight: 101.14 g/mole

Molecular Structure:

Color: Colorless to slightly yellow liquid.

 3

http://www.epa.gov/oppsrrd1/REDs/3095red.pdf
Page 8 of 40

Physical State: Liquid.

Odor: An amine odor (fishy).

Stability: Stable under ambient conditions. It does not react with steel

or iron.

pH: 10.5 to 11.5 (78% liquid)

11.0 (0.1 M aqueous solution of pure active ingredient 

(PAI))

UV/Visible absorption: The absorption maxima determined at acidic pH levels less 

than 2, neutral pH at 7.61 and a basic pH level greater than 

10 were 202-203, 203 and 207 nm, respectively.

Viscosity: 7.4 centipoise at 25°C.

Melting point: Not required for liquids.

Boiling Point: 100.9°C.

Density: 0.924 g/ml (PAI).

Bulk Density: 0.99 g/ml.

Dissociation Constants in

Water: pKa = 9.35 at 25°C.

Log Ko/w: log P = 0.73

Solubilities: Miscible with water in all proportions. It is also miscible

with methanol, ethanol, propanol, and acetone.

Vapor Pressure: 7.58 mm Hg (Source: EPI Suite).

100 mm Hg at 70-72°C.

The 78% concentrate is a solution in water. Its vapor 

pressure is the combination of pressures from the active 

ingredient and its solvent, water.

Henry's Law Constant: 1.009E-006 atm-m3/mole at 25°C (Source: EPI Suite).

Enforcement Analytical

Method: Gas chromatography.

All product chemistry data requirements have been satisfied for the active ingredient DMO

(Source: MRIDs 42941000, 42941001, 43328100, and 43328101, 443115-01).

3. Environmental Fate Summary

The only environmental fate data submitted for DMO are hydrolysis and photodegradation in 

water. Acceptable studies were conducted for both data requirements (MRID 41664801 for 

hydrolysis and 41964701 for photodegradation in water).

In the hydrolysis study, DMO apparently hydrolyzed in a matter of minutes at pHs of 5, 7, or 9, 

and no definitive rate or half-life could be determined from the study. Only a small amount of 

parent DMO (21- 43 ppm, 8.4-17 % of initial) was present soon after solution preparation 

(time=0 samples) and throughout the study. The hydrolysis products were formaldehyde and 

AMP, and AMP was stable for the length of the hydrolysis study (32 days). AMP was present at 

time=0 samples in concentrations of 207-229 ppm (83-91.6 % of dosing rate) (MRID 41664801).
Page 9 of 40

Photolysis in water is not a significant route of dissipation for DMO. In the photolysis in water 

study, the same pattern of degradation was observed. DMO apparently hydrolyzed in a matter of 

minutes in both the dark control and irradiated samples at pH 7, and no rate or half-life could be 

determined from the study. Only a small amount of parent DMO (23.4-24.4 ppm, 9.5-10.7 % of 

initial) was present soon after solution preparation (time=0 samples) and throughout the study. 

The hydrolysis products were formaldehyde and AMP, and AMP was stable for the length of the 

photolysis study (6 days). AMP was present at time=0 samples in concentrations of 220-223 ppm 

(89.3-90.5 % of dosing rate) (MRID 41960701).

DMO degrades rapidly by hydrolysis in minutes to form AMP, which is stable to abiotic 

degradation processes. Because DMO is hydrolyzed so rapidly to AMP, photodegradation 

of DMO in water is not a significant route of degradation. The Agency's in-house database 

does not have any acceptable environmental fate and transport data on the degradate, AMP. 

These data are required to assess environmental fate for the registered use patterns that may 

potentially enter waste water treatment plants (WWTPs) and subsequently be discharged to 

aquatic environments. 

AMP is on the 2007 Organization for Economic Co-operation and Development (OECD) 

list of high production volume (HPV) chemicals4 for which a Screening Information Data 

Set (SIDS) Initial Assessment Report was scheduled to be performed. A Robust Summary 

of data5

An examination of the chemical structure and a review of information in this Robust 

Summary for AMP indicate that a high percentage of AMP may be removed by 

conventional sewage treatment systems. Specifically, the biodegradation of AMP has been 

demonstrated in a laboratory ready biodegradability study to remove 89% of the 

biochemical oxygen demand (BOD) in 28 days under aerobic conditions, using non-adapted 

domestic activated sludge inoculum (OECD Guideline test 301F). The primary removal 

mechanism was attributed to mineralization.

has been submitted to the Agency. This Summary Report contained a letter 

requesting from Dow to be removed from the International Council of Chemical 

Associations (ICCA) Program and brought back to the EPA HPV Challenge Program.

To be able to give merit to this claim, the Agency would need to review and evaluate the primary 

references cited in this letter to the Agency. Without reviewing and evaluating these primary 

references and reaching the same conclusions as those presented, the Agency anticipates needing 

environmental fate data from tests including the activated sludge respiration inhibition (ASRI) 

test and depending on the outcome of the ASRI test, either a ready biodegradability test or one 

of the following simulation tests: porous pot test, or simulation tests to assess the 

biodegradability of chemicals discharged in wastewater, or simulation test -aerobic sewage 

treatment: A. Activated Sludge Units.

 4 The 2007 OECD List of High Production Volume Chemicals, Series on Testing and Assessment, Number 112,23 

October 2009. 5 letter dated 8/28/2011 from The Dow Chemical Company to Mark Townsend, Chief, HPV Chemicals Branch of 

EPA/OCSPP/OPPT
Page 10 of 40

4. Water Quality

DMO is not identified as a cause of impairment for any water bodies listed as impaired under 

section 303(d) of the Clean Water Act, based on information provided at the Agency’s National 

Pesticides Cause of Impairment of Waters website (searched April 7, 2011)

6

. In addition, no 

Total Maximum Daily Loads (TMDL) have been developed for DMO, based on information 

provided at the Agency’s National Pesticide TMDL web site (searched April 7, 2011)7

. More 

information on impaired water bodies and TMDLs can be found at 

http://www.epa.gov/owow/tmdl/. The Agency invites submission of water quality data for this 

pesticide. To the extent possible, data should conform to the quality standards in Appendix A of 

the OPP Standard Operating Procedure: Inclusion of Impaired Water Body and Other Water 

Quality Data in OPP’s Registration Review Risk Assessment and Management Process (see: 

http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1-sop.pdf ), in order to ensure 

they can be used quantitatively or qualitatively in pesticide risk assessments.

5. Ecological Effects Summary

In August of 1996 the US EPA completed its RED on the DMO case. It was determined that the 

ecotoxicological database (Table 1) was adequate to characterize the acute toxicity of DMO to 

nontarget terrestrial and aquatic organisms when used to control pests in aquatic or terrestrial 

industrial and indoor nonfood sties. Subsequently, data were called in to Troy, Dow, and 

International Specialty on October 16th, 1996. No quantitative ecological risk assessment was 

performed for DMO at the time of the RED. In the registration review a quantitative ecological 

risk assessment will be conducted for use patterns which result in discharges of the parent or 

degradates of concern to aquatic systems (i.e. metalworking fluids, industrial water process 

systems, oil well treatment and drilling muds, and consumer product uses). Because DMO 

rapidly hydrolyzes to AMP and formaldehyde, it is necessary that risk assessments focus on the 

degradates rather than the parent. Available ecotoxicity guideline studies and the results are 

summarized in Tables 1 and 2. Ecotoxicity studies with the major degradation products, 

formaldehyde and AMP, are summarized in Tables 3 and 4. 

5.1. Toxicity to Birds, Acute and Subacute

There are two avian acute oral toxicity studies, one (MRID 42967201) with a waterfowl

species the mallard duck (Anas platyrhynchos) and the other with a gamebird species 

(MRID 0076970), bobwhite quail (Colinus virginianus) (Table 1). The test performed on 

the mallard duck (MRID 0076970) was categorized as “supplemental” but the bobwhite 

quail study is classified as acceptable and provides a definitive acute oral LD50 value. 

The bobwhite quail were more sensitive to DMO than the mallard duck on an acute oral 

basis. There is also sub-acute dietary studies with both species and in both studies the 

highest DMO concentration in the diet were below the LC50 so no definitive LC50 value 

 6 . http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885 7

http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant_

group_name=PESTICIDES
Page 11 of 40

could be established. While the highest concentration tested in both studies were below 

the guideline standard of 5000 ppm-diet for a limit test, the studies were classified as 

acceptable. Because DMO rapidly hydrolyzes, exposure of nontarget avian species to 

DMO from registered use patterns is not expected and therefore this information is 

acceptable and no further testing is required for registration review.

No other avian tests have been submitted to the Agency since the 1996 RED. It is not 

necessary to call in an avian reproduction study at this time for DMO; based on the fate 

properties discussed above as birds are not expected to be subjected to repeated or 

continued exposure to DMO.

TABLE 1. Ecotoxicity Data Summary for DMO

MRID No Guideline Common 

Name

Taxonomic 

Name

Test 

Type % a.i. Study Duration Endpoint Toxicity Units Status Tox. Category

42967201 850.2100 Bobwhite 

Quail

Colinus 

virginianus O 76% 14 D LD50 705 mg/kgbw Acceptable Slightly toxic

76970 850.2100 Mallard Duck Anas 

platyrhynchos O 78% 14 D LD50 >1105 mg/kgbw Supplemental Moderately toxic

102975 71-2a Bobwhite 

Quail

Colinus 

virginianus D 78% 8 D LC50 >3250 ppm Acceptable Slightly toxic

102976 71-2b Mallard Duck Anas 

platyrhynchos D 78% 8 D LC50 >4008 ppm Acceptable Slightly toxic

68770 850.1075 Rainbow Trout Oncorhynchus 

mykiss S Tech 96 hr LC50 95 ppm Supplemental (Downgraded) Slightly toxic

76969 850.1075 Bluegill 

Sunfish

Lepomis 

macrochirus S 77% 96 hr LC50 59 ppm Supplemental (Downgraded) Slightly toxic

Freshwater Invertebrate Acute Toxicity

76968 850.1010 Water Flea Daphnia 

magna S 77% 48 hr EC50 45 ppm Supplemental (Downgraded) Slightly toxic

102974 850.1075 Sheepshead 

Minnow

Cyprinodon 

variegatus S 82% 96 hr LC50 218 ppm Supplemental (Downgraded)

Practically nontoxic

76967 850.1035 Pink Shrimp Penaeus 

duorarum S 77% 96 hr LC50 230 ppm Supplemental (Downgraded)

Practically nontoxic

102973 850.1025 Eastern Oyster Crassostrea 

virginica F 83% 96 hr EC50 9.2 ppm Acceptable Moderately toxic

Test Type—O: oral; D: dietary; S: static; F: flow-through. Units—mg/kg-bw: milligrams per kilogram-body weight; ppm: parts per million 

(equivalent to milligrams per kilogram-diet (mg/kg-diet) for dietary exposure and milligrams per liter (mg/L) for aquatic exposures). Categories 

of acute toxicity for aquatic organisms (U.S. EPA, 2004) based on EC50 or LC50 (mg/L): < 0. 1 very highly toxic; 0.1-1 highly toxic; >1-10 

moderately toxic; >10-100 slightly toxic; >100 practically nontoxic. Categories of acute toxicity to terrestrial animals (avian and mammalian) 

(U.S. EPA, 2004). LC50 (ppm): < 50 very highly toxic; 50 - 500 highly toxic; 501 – 1000 moderately toxic; 1001-5000 slightly toxic; >5000 

practically non-toxic. LD50 (mg/kg-bw): < 10 very highly toxic; 10 - 50 highly toxic; 51 - 500 moderately toxic; 501-2000 slightly toxic; >2000 

practically non-toxic.
Page 12 of 40

TABLE 2. Ecotoxicity Data Summary for EP (BiobanTM CS-1135)

MRID No. Guideline Common 

Name

Taxonomic 

Name

Test 

Type

% 

a.i.

Study 

Duration Endpoint Toxicity Units Status Tox. Category

48559603 850.1400 Fathead 

Minnow

Pimephales 

promelas F EP 33 D NOEC ≥10 ppm

Supplemental 

Upgradeable 

Pending AMP 

Data

Not 

applicable

48534004 850.1010 Water Flea Daphnia 

magna

S EP 48 hr EC50 57 ppm

Supplemental 

Upgradeable 

Pending AMP 

Data

Slightly 

Toxic

48559602 850.1300 Water Flea Daphnia 

magna

S EP 21 D NOEC 5.0 ppm

Supplemental 

Upgradeable 

Pending AMP 

Data

Not 

applicable

48534002 850.1075 Sheepshead 

Minnow

Cyprinodon 

variegatus SR EP 96 hr LC50 >100 mg/L

Supplemental 

Upgradeable 

Pending AMP 

Data

Practically 

Non-Toxic

48534003 850.5400 Marine 

Diatom

Skeletonema 

costatum S EP 96 hr IC50

(yield) 4.0 mg/L

Supplemental 

Upgradeable 

Pending AMP 

Data

Not appliable

Test Type—O: oral; D: dietary; S: static; SR: static renewal; F: flow-through. Unit—mg/kg-bw: milligrams per kilogram-body weight; ppm: 

parts per million (equivalent to milligrams per kilogram-diet (mg/kg-diet) for dietary exposure and milligrams per liter (mg/L) for aquatic 

exposures). Categories of acute toxicity for aquatic organisms (U.S. EPA, 2004) based on EC50 or LC50 (mg/L): < 0. 1 very highly toxic; 0.1-1 

highly toxic; >1-10 moderately toxic; >10-100 slightly toxic; >100 practically nontoxic. Categories of acute toxicity to terrestrial animals, avian 

and mammalian (U.S. EPA, 2004). LC50 (ppm): < 50 very highly toxic; 50 - 500 highly toxic; 501 – 1000 moderately toxic; 1001-5000 slightly 

toxic; >5000 practically non-toxic. LD50 (mg/kg-bw): < 10 very highly toxic; 10 - 50 highly toxic; 51 - 500 moderately toxic; 501-2000 slightly 

toxic; >2000 practically non-toxic.

5.2. Toxicity to Freshwater Aquatic Animals

5.2.1 Freshwater Fish

Acute toxicity tests for two species of fish using DMO were submitted and reviewed by 

the Agency (MRIDs 00068770 and 00076969): rainbow trout (Oncorhynchus mykiss)

was used as the cold water species and bluegill sunfish (Lepomis macrochirus) was used 

as the warm water species; both of these species are preferred for acute toxicity testing. 

The studies are conducted under static conditions and no analytical measurements were 

made for the test substance. Given that the aquatic aerobic half-life of DMO is less than 

one hour, the parent was not likely stable under test conditions. To maintain stable 

exposure concentrations given the expected half-life, the tests should have been 

conducted under flow-through conditions and analytical measurements made at a 

frequency and timing to document stability throughout the study duration. These results 

provide only supplemental information about the toxicity of DMO and its degradates and 

are expected to underestimate the acute sensitivity of DMO to fish. In regards to 

exposure to the hydrolysis degradate AMP and formaldehyde, the studies are still 

supplemental as no measurements of the concentrations of these and their stability 

throughout the duration of the study is documented. However, these 96-hour acute 

studies still indicate that DMO and its resultant degradates can be expected to be at least 

slightly toxic to both cold and warm water fish. These studies were originally classified 
Page 13 of 40

as acceptable, but the issues of DMO stability or stability of its degradates throughout the 

study duration were not noted or discussed. These studies were downgraded to 

supplemental because the studies do not document the stability, and fate information 

indicates that stability of DMO and AMP was not likely. These studies are expected to 

underestimate the acute sensitivity of DMO and AMP to fish.

The data requirements for DMO are not fulfilled; however since nontarget aquatic 

organisms are expected to be exposed to the degradation product (AMP) rather than the 

parent for the given registered uses, further DMO studies are not required at this time. 

A fish, early-life stage study on the freshwater species, Fathead Minnow (Pimephales 

promelas) under flow-through conditions using EP BIOBANTM CS-1135, was recently 

submitted to the Agency and is supplemental, upgradable pending the Agency receives a 

methodological explanation for BIOBANTM CS-1135 measurements (MRID 48559603)

(see Table 2). BIOBANTM CS-1135 is known to be hydrolytically unstable and to rapidly 

degrade to AMP. Due to this known property of the test substance to rapidly degrade in 

water, the study author stated that the high treatment level was not analyzed for the parent 

substance, however all data were reported in terms of BIOBANTM CS-1135. Further 

clarification of the methodology and AMP concentrations, if AMP was measured, is 

necessary before upgrading this study. Depending on the data received, this may satisfy 

like guideline data requirements for the degradation product, AMP.

5.2.2 Freshwater Invertebrates

The minimal testing required in order to establish the acute toxicity of AMP to freshwater 

invertebrates is a freshwater aquatic invertebrate toxicity test, preferably using first instar 

Daphnia magna or early instar amphipods, stoneflies, mayflies, or midges. A 48-hour 

acute toxicity study (MRID 00076968) was conducted with the water flea (Daphnia 

magna) using DMO; however, this study provides only supplemental information as it 

was conducted under static conditions but based on fate information DMO is not 

expected to be stable under study conditions. This study was originally classified as

acceptable, but the issues of stability were not noted or discussed. This study was 

downgraded to supplemental because the study does not document the stability (no 

analytical measurements were made for DMO or its degradates), and fate information 

indicates that stability was not likely. This study is expected to underestimate the acute 

sensitivity of DMO and degradates to aquatic invertebrates. The acute endpoint result 

from this supplemental study is listed in Table 1 and it is expected to underestimate the 

acute sensitivity of DMO and its degradates to freshwater invertebrates; however, the 

study still indicates that DMO and its degradates can be expected to be at least slightly 

toxic to freshwater invertebrates. The data requirement for an acute freshwater 

invertebrate are not fulfilled; however since nontarget aquatic organisms are expected to 

be exposed to the degradation product (AMP) rather than the parent, further DMO studies 

are not required at this time. 

An acute toxicity study and a chronic toxicity study with Daphnia magna using EP 

BIOBANTM CS-1135 under flow-through conditions, was recently submitted to the 

Agency and both are supplemental but upgradable pending the Agency receives a 
Page 14 of 40

methodological explanation for BIOBANTM CS-1135 measurements (MRIDs 48534004 

and 48559603) (see Table 2). BIOBANTM CS-1135 is known to be hydrolytically 

unstable and to rapidly degrade to AMP. Due to this known property of the test 

substance to rapidly degrade in water, the study author stated that the high treatment level 

was not analyzed for the parent substance, however all data were reported in terms of 

BIOBANTM CS-1135. Further clarification of the methodology and AMP concentrations, 

if AMP was measured, is necessary before upgrading these studies. Depending on the 

data received, this may satisfy like guideline data requirements for the degradation 

product, AMP.

5.3. Toxicity to Estuarine and Marine Animals

Acute toxicity data from studies using DMO with Pink Shrimp (Penaeus duorarum), 

Eastern Oyster (Crassostrea virginica), and Sheepshead Minnows (Cyprinodon 

variegatus) (MRIDs 76967, 102973, and 102974) were submitted to and reviewed by the 

Agency. Although the estuarine/marine acute toxicity studies with Pink Shrimp and 

Sheepshead Minnow were deemed acceptable in their initial reviews by the EPA (MRID 

76967 and 102974), they have been downgraded to supplemental because the studies are 

conducted under static conditions and no analytical measurements were made for the test 

substance. Given that the hydrolysis half-life of DMO is less than one hour, the parent 

was not likely stable under test conditions but there were also no analytical measurements 

made on the degradates, so their concentrations and stability throughout the test are 

unknown. The results of these supplemental studies are listed in Table 1 and they are 

expected to underestimate the acute sensitivity of DMO and its degradates to 

estuarine/marine organisms. The data requirements for DMO acute estuarine/marine 

organisms testing are not fulfilled; however since nontarget aquatic organisms are 

expected to be exposed to the degradation product (AMP) rather than the parent, further 

studies are not required at this time. These aforementioned studies (Table 1) indicate that 

DMO is at least practically non-toxic to estuarine fish and shrimp species, while 

moderate toxicity was observed for Eastern Oysters exposed to this chemical. 

A fish acute toxicity test on the Sheepshead Minnow (Cyprionodon variegates) using EP 

BIOBANTM CS-1135 under flow-through conditions, was recently submitted to the 

Agency and is supplemental, upgradable pending that the agency received a 

methodological explanation for BIOBANTM CS-1135 measurements (MRID 48534002)

(see Table 2). BIOBANTM CS-1135 is known to be hydrolytically unstable and to rapidly 

degrade to AMP. Due to this known property of the test substance to rapidly degrade in 

water, the study author stated that the high treatment level was not analyzed for the parent 

substance, however all data were reported in terms of BIOBANTM CS-1135. Further 

clarification of the methodology and AMP concentrations, if AMP was measured, is 

necessary before upgrading this study. Depending on the data received, this may satisfy 

guideline data requirements for the degradation product, AMP.
Page 15 of 40

5.4. Toxicity to Aquatic Plants

No toxicity testing with an aquatic vascular or an emergent plant are available for DMO. 

Because of the rapid degradation of DMO into AMP and formaldehyde, no additional 

testing of DMO with aquatic plants is needed for the ecological risk assessment.

An algal toxicity test using the EP BIOBANTM CS-1135, was recently submitted to the 

Agency and is supplemental, upgradable pending that the Agency receives a 

methodological explanation for BIOBANTM CS-1135 measurements at test initiation and 

termination (MRID 48534003) (see Table 2). BIOBANTM CS-1135 is known to be 

hydrolytically unstable and to rapidly degrade to AMP. Due to this known property of 

the test substance to rapidly degrade in water, the study author stated that the high 

treatment level was not analyzed for the parent substance, however all data were reported 

in terms of BIOBANTM CS-1135. Further clarification of the methodology and AMP 

concentrations, if AMP was measured, is necessary before upgrading this study. 

Depending on the data received, this may satisfy like guideline data requirements for the 

degradation product, AMP.

5.5. Toxicity of Degradation Products

Exposure to nontarget organisms is more likely to be from its degradation products, AMP 

and formaldehyde, and not the parent compound DMO, which is expected to rapidly degrade 

(see fate summary) in aqueous environments. Toxicity information is needed to address 

discharge of these to the aquatic environment from discharge to WWTPs.

5.5.1 AMP

An ecotoxicity summary report (DP Barcode # D208128) suggests that AMP may be 

the true active ingredient of Bioban CS-1135 and the chemical of major concern in 

regard to any chronic effects to aquatic organisms. A summary of the ecotoxicity data 

for AMP is provided in Table 3, the data in this table were obtained from a summary 

provided for OPPT’s HPV Challenge8

5.5.1.1. Toxicity to Avian Species

. While the data are posted as part of the HPV 

Challenge program the applicability of such data for use in this risk assessment is 

unknown without sufficient study details. If this data is submitted, the Agency will 

review these studies for acceptability in meeting the data requirements.

There is no acute or chronic toxicity data with an avian species with AMP. As birds 

can be exposed to AMP in their drinking water an acute oral toxicity test with AMP 

using the species observed to be more sensitive to the parent DMO, the bobwhite quail 

is needed to evaluate acute risks to avian species.

No avian reproduction study with AMP is required at this time; based on exposure to 

AMP does not meet any of the following criteria:

 8 Letter dated 8/28/2011 from The Dow Chemical Company to Mark Townsend, Chief, HPV Chemicals Branch of 

EPA/OCSPP/OPPT
Page 16 of 40

• AMP is not stable in the environment to the extent that a potentially chronic toxic 

amount may persist in avian food;

• AMP is not expected to be stored or accumulated in plant or animal tissue, as 

indicated by its low octanol/water partition coefficient.

TABLE 3. Ecotoxicity Data Summary for AMP (HPV Database)

Common 

Name Taxonomic Name Test Type Study Duration Endpoint Toxicity Units Tox. Category

Bluegill 

Sunfish

Lepomis 

macrochirus S 96 hr LC50 190 ppm Practically nontoxic

Ide Leuciscus idus S 48 hr LC50 331 ppm Practically nontoxic

European 

Plaice

Pleuronectes 

platessa F 96 hr LC50 184 ppm Practically nontoxic

Water Flea Daphnia magna S 48 hr EC50 193 ppm Practically nontoxic

Brown 

Shrimp Cragnon cragnon F 96 hr EC50 179 ppm Practically nontoxic

Test Type—O: oral; D: dietary; S: static; F: flow-through. Unit—mg/kg-bw: milligrams per kilogram-body weight; ppm: parts per million 

(equivalent to milligrams per kilogram-diet (mg/kg-diet) for dietary exposure and milligrams per liter (mg/L) for aquatic exposures) Categories of 

acute toxicity for aquatic organisms (U.S. EPA, 2004) based on EC50 or LC50 (mg/L): < 0. 1 very highly toxic; 0.1-1 highly toxic; >1-10 

moderately toxic; >10-100 slightly toxic; >100 practically nontoxic. Categories of acute toxicity to terrestrial animals, avian and mammalian 

(U.S. EPA, 2004). LC50 (ppm): < 50 very highly toxic; 50 - 500 highly toxic; 501 – 1000 moderately toxic; 1001-5000 slightly toxic; >5000 

practically non-toxic. LD50 (mg/kg-bw): < 10 very highly toxic; 10 - 50 highly toxic; 51 - 500 moderately toxic; 501-2000 slightly toxic; >2000 

practically non-toxic.

5.5.1.2. Toxicity to Freshwater Fish and Invertebrates

To establish the toxicity of the major degradation product, AMP, to freshwater fish, one 

fish acute toxicity study using the most sensitive TGAI species is required. One such 

study has been submitted to the EPA via OPPT’s HPV Challenge. Although this study 

is considered acceptable for risk assessments conducted in the OPPT, under the TSCA, 

the study details would need to be submitted to the OPP for the data to be used in the 

risk assessment for FIFRA registration review. The data requirement is considered not 

fulfilled until such data is submitted.

Freshwater Fish, Acute and Chronic Toxicity

No chronic data are available for DMO’s major degradation product with freshwater 

fish. Because uses of DMO will result in repeated discharge of its major degradation 

product, AMP, to aquatic environments, a fish early life stage test with AMP is 

required. There should be an acute toxicity test available for the same species used in 

the chronic study.
Page 17 of 40

To establish the toxicity of the major degradation product, AMP, to freshwater 

invertebrates, one invertebrate acute toxicity study using the Daphnia sp. is required. 

One such study exists in OPPT’s HPV Challenge program. Although this study is 

considered acceptable for risk assessments conducted in the OPPT, under the TSCA, 

the study details would need to be submitted to the OPP for the data to be used in the 

risk assessment for FIFRA registration review. The data requirement is considered not 

fulfilled until such data is submitted.

Freshwater Invertebrate, Acute and Chronic Toxicity

No chronic data are available for DMO’s major degradation product with freshwater 

invertebrates. Because uses of DMO will result in repeated discharge of its major 

degradation product, AMP, to aquatic environments, an aquatic invertebrate life-cycle 

study test is required using the freshwater species, Daphnia magna.

5.5.1.3. Toxicity to Estuarine/Marine Fish and Invertebrates

Acute toxicity testing with estuarine and marine organisms is required when an end-use 

product is intended for direct application to the marine/estuarine environment or is 

expected to reach this environment in significant concentrations. The aquatic industrial 

use pattern of oil recovery for DMO may result in exposure to the estuarine 

environment, and discharges from WWTPs discharging to estuarine or marine waters 

for consumer product uses, water processing systems, etc. will result in exposure of 

aquatic organisms in this environment.

Because the major degradation product, AMP, is expected to reach estuarine or marine 

environments, one estuarine/marine acute fish toxicity study, one acute crustacean 

toxicity study, and one mollusk study are required. An estuarine/marine acute fish 

toxicity study and an estuarine/marine acute crustacean toxicity study have been 

submitted to the EPA via OPPT’s HPV Challenge Program. Although these studies are 

considered acceptable for risk assessments conducted in the OPPT, under the TSCA, 

the study details would need to be submitted to the OPP for the data to be used in the 

risk assessment for FIFRA registration review. These data requirements are considered 

not fulfilled until such data is submitted. Additionally, a mollusk embryo larvae study 

or shell deposition study is required with AMP. 

No chronic data are available for DMO’s major degradation product with 

estuarine/marine invertebrates. A mysid life cycle study with AMP is required as 

chronic exposure has the potential to occur. With an acceptable mysid acute study the 

chronic data would allow confirmation that the acute-to-chronic ratio does not differ 

between saltwater and freshwater organisms, indicating that mode of action does not 

differ greatly between saltwater and freshwater species for the degradation product, 

AMP. 
Page 18 of 40

5.5.1.4. Toxicity to Aquatic Plants

No algal toxicity data have been submitted for the major degradation product, AMP. 

For the ecological risk assessment, including an endangered species assessment for all 

uses, the Agency anticipates needing algal toxicity data.

No toxicity testing with an aquatic vascular Lemna sp. has been submitted for its major 

degradation product, AMP. One test with the major degradation product, AMP, is 

required.

No seedling emergence and growth test for its major degradation products are available. 

For uses where the antimicrobial is expected to reach aquatic environments, a seedling 

emergence and growth study with rice is required. Because of the rapid degradation of 

DMO in the environment and the repeated discharge and stability of AMP, the major 

degradation product, AMP, is required.

5.5.2 Formaldehyde

Toxicity endpoints for formaldehyde from data submitted to OPP are presented below in 

Table 4. This data indicates the following: 

• Formaldehyde (up to 37% ai) is slightly toxic to avian species on an acute oral basis 

and practically non-toxic to avian species through subacute dietary exposure and is 

not expected to pose a significant hazard to avian species on an acute or subacute 

basis. 

• Formaldehyde (up to 37% ai) is slightly to practically non-toxic to freshwater fish on 

an acute basis and is not expected to pose a significant hazard to freshwater fish 

species.

• Formaldehyde (up to 37% ai) is slightly toxic to freshwater invertebrates as indicated 

by a supplemental study that does not fulfill guideline requirements (72-2a/OPPTS 

850.1010) and must be repeated.

• The results of a core study in the silverside (148770), an acceptable (or core) study in 

the pink shrimp (148770), and an acceptable (or core) study in the eastern oyster 

(148770) indicate that formaldehyde is slightly toxic to estuarine/marine fish and 

practically non-toxic to moderately toxic to estuarine/marine invertebrates on an acute 

basis. Supplemental studies in invertebrates indicate that formaldehyde is moderately 

toxic to shrimp, highly toxic to eastern oysters, and practically non-toxic to fiddler 

crabs.

TABLE 4. Ecotoxicity Data Summary for Formaldehyde

MRID 

No Guideline Common Name

Taxonomic 

Name

Test 

Type % a.i. Study Duration Endpoint Toxicity Units Status Tox. Category

148774 850.2100 Bobwhite 

Quail

Colinus 

virginianus O 37% 21 D LD50 790 mg/kgbw A Slightly toxic
Page 19 of 40

MRID 

No Guideline Common Name

Taxonomic 

Name

Test 

Type % a.i. Study Duration Endpoint Toxicity Units Status Tox. Category

148773 850.2200 Bobwhite 

Quail

Colinus 

virginianus D 37% 8 D LC50 >5000 ppm A Practically nontoxic

148775 850.2200 Mallard 

Duck

Anas 

platyrhynchos D 37% 8 D LC50 >5000 ppm A Practically nontoxic

132485 850.1075 Rainbow 

Trout

Oncorhynchus 

mykiss S 37% 96 hr LC50 118 ppm A Practically nontoxic

101857 850.1075 Rainbow 

Trout

Oncorhynchus 

mykiss S 25.90% 96 hr LC50 73.3 ppm S Slightly toxic

101857 850.1075 Rainbow 

Trout

Oncorhynchus 

mykiss S 32.37% 96 hr LC50 2.24 ppm S Moderately toxic

101857 850.1075 Rainbow 

Trout

Oncorhynchus 

mykiss S 27.75% 96 hr LC50 1.41 ppm S Moderately toxic

134124 850.1075 Rainbow 

Trout

Oncorhynchus 

mykiss S 18.80% 96 hr LC50 >100 ppm S Practically nontoxic

132485 850.1075 Bluegill 

Sunfish

Lepomis 

macrochirus S 37% 96 hr LC50 100 ppm S Slightly toxic

101857 850.1075 Bluegill 

Sunfish

Lepomis 

macrochirus S 25.90% 96 hr LC50 41.4 ppm S Slightly toxic

101857 850.1075 Bluegill 

Sunfish

Lepomis 

macrochirus S 32.37% 96 hr LC50 1.79 ppm S Moderately toxic

101857 850.1075 Bluegill 

Sunfish

Lepomis 

macrochirus S 27.75% 96 hr LC50 1.51 ppm S Moderately toxic

134126 850.1075 Bluegill 

Sunfish

Lepomis 

macrochirus S 37% 96 hr LC50 68 ppm S Slightly toxic

134123 850.1075 Bluegill 

Sunfish

Lepomis 

macrochirus S 8.80% 96 hr LC50 >118 ppm S Practically nontoxic

132485 Atlantic 

Salmon Salmo salar S 37% 96 hr LC50 173 ppm S Practically nontoxic

132485 Lake Trout Salvelinus 

namaycush S 37% 96 hr LC50 100 ppm S Slightly toxic

132485 Black 

Bullhead

Ameiurus 

melas S 37% 96 hr LC50 62.1 ppm S Slightly toxic

148772 850.1010 Water Flea Daphnia 

magna

S 37% 48 hr LC50 14.31 ppm S Slightly toxic

148770 850.1075 Silverside Menidia 

menidia S 37% 96 hr LC50 69 ppm A Slightly toxic

148770 850.1035 Pink 

Shrimp

Penaeus 

duorarum S 37% 96 hr LC50 143 ppm A Practically nontoxic

126396 850.1035 Pink 

Shrimp

Panaeus 

duorarum S 28% 96 hr LC50 7.6 ppm S Moderately toxic
Page 20 of 40

MRID 

No Guideline Common Name

Taxonomic 

Name

Test 

Type % a.i. Study Duration Endpoint Toxicity Units Status Tox. Category

128086 Pink 

Shrimp

Panaeus 

duorarum S 26% 96 hr LC50 358 ppm S Practically nontoxic

126394 Pink 

Shrimp

Panaeus 

duorarum S 32% 96 hr LC50 12 ppm S Slightly toxic

148770 Eastern 

Oyster

Crassostrea 

virginica S 37% 48 hr EC50 1.8 ppm S Moderately toxic

126396 Eastern 

Oyster

Crassostrea 

virginica S 28% 48 hr EC50 0.3 ppm S Highly toxic

128086 Eastern 

Oyster

Crassostrea 

virginica S 26% 48 hr EC50 2.9 ppm S Moderately toxic

126394 Eastern 

Oyster

Crassostrea 

virginica S 32% 48 hr EC50 0.47 ppm S Highly toxic

128086 Fiddler 

Crab Uca pugilator S 26% 96 hr LC50 >1000 ppm S Practically nontoxic

126396 Fiddler 

Crab Uca pugilator S 28% 96 hr EC50 380 ppm S Practically nontoxic

126394 Fiddler 

Crab Uca pugilator S 32% 96 hr EC50 290 ppm S Practically nontoxic

65640 Florida 

Pompano

Trachinotus 

carolinus S 37% 96 hr LC50 69 ppm S Slightly toxic

Test Type—O: oral; D: dietary; S: static; F: flow-through. Units—mg/kg-bw: milligrams per kilogram-body weight; ppm: parts per million 

(equivalent to milligrams per kilogram-diet (mg/kg-diet) for dietary exposure and milligrams per liter (mg/L) for aquatic exposures). Status—S: 

Supplemental; A: Acceptable. Categories of acute toxicity for aquatic organisms (U.S. EPA, 2004) based on EC50 or LC50 (mg/L): < 0. 1 very 

highly toxic; 0.1-1 highly toxic; >1-10 moderately toxic; >10-100 slightly toxic; >100 practically nontoxic. Categories of acute toxicity to 

terrestrial animals, avian and mammalian (U.S. EPA, 2004). LC50 (ppm): < 50 very highly toxic; 50 - 500 highly toxic; 501 – 1000 moderately 

toxic; 1001-5000 slightly toxic; >5000 practically non-toxic. LD50 (mg/kg-bw): < 10 very highly toxic; 10 - 50 highly toxic; 51 - 500 moderately 

toxic; 501-2000 slightly toxic; >2000 practically non-toxic.

6. Facility Emissions to WWTP Modeling

For assessing the fate of DMO and its major degradates or reaction products emitted to receiving 

waters from industrial process water uses of DMO such as metal working fluids, oilfield water 

systems, oilfield drilling muds and workover and completion fluids, and consumer household 

and industrial products, the Agency anticipates using the available environmental fate 

information from guideline studies for DMO and its major degradates and the following 

emissions scenarios:

• Potential environmental releases and associated exposures of concern for 

antimicrobial uses related to consumer products including dishwashing and laundry 

liquids, surface cleaners and polishes, will be those identified in the down the drain 

module of EFAST for consumer products.
Page 21 of 40

• Potential environmental releases and associated exposures of concern for 

antimicrobial uses related to the metalworking industry will be those identified in 

“Emissions Scenario Document on the Use of Metalworking Fluids”, Number 28 of 

OECD Series on Emission Scenario Documents dated July 6, 2011.

• Potential environmental releases and associated exposures of concern for 

antimicrobial uses related to the Oil Well Treatment Industry (oilfield water systems)

will be those identified in the “New Chemical Scenario for Well Treatment 

Chemicals” within the latest version of Generic Scenarios developed by the Chemical 

Engineering Branch of the US EPA Office of Pollution Prevention and Toxics 

(OPPT).

• Potential environmental releases and associated exposures of concern for 

antimicrobial uses related to the Oil and Gas Well Production Industry will be those 

identified in the latest version of the OECD Emission Scenario Document for the Oil 

Well Production Industry or the “New Chemical Scenario for Drilling Muds” within

the latest version of Generic Scenarios developed by the Chemical Engineering 

Branch of the OPPT. In the latter, it is assumed that all of the production volume is 

disposed of by landfill unless the submitter states that the product is to be used in 

water-based muds for offshore drilling, in which case it is assumed that intermittent 

ocean discharges occur at 5,000 kg/site. 

Facility information is needed to estimate aquatic exposures from emissions to wastewater 

treatment plants (WWTP) for each emissions scenario and directly to water from the oil and gas 

well development sites. The agency will make stringent assumptions in the absence of the 

following data: 

• The portion of the production volume of DMO used in consumer household and 

industrial laundry and cleaning products;

• The number of metalworking sites using DMO or the maximum annual production 

volume of DMO used in metalworking facilities in the United States and its 

territories;

• The number of oil and gas well development sites using DMO or the maximum 

annual production volume of DMO in oil and gas well development in the United 

States and its territories;

• How many of each of these facilities (metalworking, oil and gas well development) 

have on-site and/or off-site wastewater treatment.

In the absence of information on the number of these facilities that use DMO and how many of 

these facilities have on-site and/or off-site wastewater treatment, the Agency will assume that all 

such facilities in the United States have the potential to use DMO.

In the absence of appropriate test data on biodegradation during wastewater treatment, the 

Agency will assume that there is no removal of AMP during wastewater treatment and that the 

amount of AMP released with the effluent from a wastewater treatment facility will be the same 

as the amount entering the wastewater treatment facility. In the absence of data on the percent 

removal of AMP during drinking water treatment the Agency will assume there is no removal of 

AMP.
Page 22 of 40

7. Environmental Fate and Ecotoxicity Data Gaps and Anticipated 

Work

DMO degrades rapidly by hydrolysis in minutes to form AMP (CAS No. 124-68-5), which 

is stable to abiotic degradation processes. Because DMO is hydrolyzed so rapidly to AMP, 

photodegradation of DMO in water is not a significant route of degradation. The Agency's 

in-house database does not have any acceptable environmental fate and transport data on the 

degradate, AMP. These data are required to assess environmental fate for the registered use 

patterns that may potentially enter waste water treatment plants (WWTPs) and subsequently 

be discharged to aquatic environments. 

An examination of the chemical structure and a review of information in a Robust Summary 

for AMP indicate that a high percentage (~89%) of AMP may be removed by conventional 

sewage treatment systems. The primary removal mechanism was attributed to 

mineralization. 

To be able to give merit to this claim, the Agency would need to review and evaluate the primary 

references cited in this letter to the Agency. Without reviewing and evaluating these primary 

references and reaching the same conclusions as those presented, the Agency anticipates needing 

environmental fate data from tests including the activated sludge respiration inhibition (ASRI) 

test and depending on the outcome of the ASRI test, either a ready biodegradability test or one 

of the following simulation tests: porous pot test, or simulation tests to assess the 

biodegradability of chemicals discharged in wastewater, or simulation test -aerobic sewage 

treatment: A. Activated Sludge Units.

• The Agency anticipates needing the following environmental fate data (guideline line 

number (GLN)) in order to conduct a complete environmental fate assessment:

o Activated Sludge Sorption Isotherm (GLN 835.1110);

o Anaerobic aquatic metabolism for the degradate AMP (GLN 835.4400);

o Aerobic aquatic metabolism for the degradate AMP (GLN 835.4300);

o Ready biodegradability (GLN 835.3110), or Porous Pot Test (GLN 835.3220), or

Simulation Tests to Assess the Biodegradability of Chemicals Discharged to 

Wastewater (GLN 835.3280), or Simulation Test – Aerobic Sewage Treatment: 

A. Activated Sludge Units(GLN 835.3240) for AMP9

.

 9 The results of the Activated Sludge Respiration Inhibition Test (ASRI) determine which of these biodegradation 

tests are required. If the ASRI test EC50 is less than or equal to 20 mg/L, then either the Biodegradation in Activated 

Sludge Study or the Porous Pot Test is required. If the ASRI test EC50 is greater than 20 mg/L, then the applicant

must choose either: (i) Ready Biodegradability or (ii) Biodegradation in Activated Sludge or the Porous Pot Test. If 

the antimicrobial passes the ready biodegradability study, then no further testing is required. If, however, the 

antimicrobial fails the ready biodegradability study, then the Biodegradation in Activated Sludge or the Porous Pot 

study is required.
Page 23 of 40

The Agency is aware that data on the fate of DMO and its degradates on sewage treatment have 

been submitted to the OPPT. If the registrant has access to these studies, they can be submitted 

to OPP for review to meet the data requirements.

• The Agency anticipates needing the following ecotoxicity data in order to conduct a 

complete ecological risk assessment, including an endangered species assessment: 

Waste Water Microbes

o Activated Sludge Respiration Inhibition for AMP (GLN 850.6800 or OECD 209);

Avian Species

o Avian acute oral toxicity test, using the bobwhite quail for AMP (OCSPP 

850.2100);

Freshwater Fish Species

o Freshwater fish acute toxicity, most a.i. sensitive species the bluegill sunfish—

major degradation product, AMP (OCSPP 850.1075);

o Fish early-life stage toxicity test, freshwater species with the same species acute 

toxicity is conducted on (bluegill sunfish)—major degradation product, AMP 

(OCSPP 850.1400);

Freshwater Invertebrate Species

o Freshwater invertebrate acute toxicity, Daphnia magna—major degradation 

product, AMP (OCSPP 850.1010);

o Aquatic invertebrate life-cycle, freshwater Daphnia magna— major degradation 

product, AMP (OCSPP 850.1300);

Estuarine/Marine Animal Species

o Estuarine/marine fish acute toxicity study—major degradation product, AMP 

(OCSPP 850.1075);

o Estuarine/marine invertebrate acute toxicity using the saltwater mysid— major 

degradation product, AMP (OCSPP 850.1035);

o Mollusk embyro larvae or shell deposition study— major degradation product, 

AMP (OCSPP 850.1055 or 850.1025);

o Aquatic invertebrate life-cycle, saltwater Americamysis bahia— major 

degradation product, AMP (OCSPP 850.1350);

Aquatic Plant Species

o Seedling emergence (Tier II) with rice— major degradation product, AMP 

(OCSPP 850.4225);

o Aquatic plant toxicity test using Lemna spp.— major degradation product, AMP 

(OCSPP 850.4400);

o Algal toxicity (Tier II) for four species— major degradation product, AMP 

(OCSPP 850.5400).
Page 24 of 40

The Agency is aware that data on the ecotoxicity of DMO’s degradation product, 

AMP, have been submitted to OPPTS. While the data is posted as part of the HPV 

Challenge program the applicability of such data for use in this risk assessment is 

unknown without sufficient study details. Such details cannot be provided to OPP 

without consent of the owner’s of the data. If the registrant has access to these 

studies, they can be submitted to OPP for review to meet data requirements.
Page 25 of 40

Appendix A Summary of Registration Information

Table 1. Registered Products of 4,4-Dimethyloxazolidine

EPA 

Registration#

Registration

Name

Company

Name Formulation Type

% of 

Active 

Ingredient

Use Patterns

464-660

Bioban CS-1135 

Antimicrobial 

Agent

The Dow Chemical 

Co. 

Ready-to-Use 

Solution 78

Material Preservative 

and Industrial Process 

and water systems: 

oilfield water systems

464-664 Bioban CS-40l 

Preservative

The Dow Chemical 

Co.

Ready-to-Use 

Solution 38

Industrial Process and 

water systems:

oilfield water systems

1529-32 Nuosept 101 

Preservative

International 

Specialty Products 

Ready-to-Use 

Solution 77 Material Preservative

1529-37 Nuosept 166 

Preservative

International 

Specialty Products Soluble Concentrate 65.63 Material Preservative

5383-82 Troysan 192 II Troy Chemical Corp Ready-to-Use 

Solution 73.7

Material Preservative 

and Industrial Process 

and water systems: 

oilfield water systems

5383-90 Troysan 186 

Formula II Troy Chemical Corp Soluble Concentrate 68 Material Preservative

Table 2. Registered Use Sites

Site Name

Materials Preservatives

Adhesives (non-food contact)

Adhesives (Joint Cements)

Adhesives (Nonfood Contact Preservative Incorporation)

Antimicrobial

Caulking Compounds

Cleansers

Dispersed Colors

Drilling Muds, and Workover & Completion Fluids

Die-Cast Lubricants and Mold-Release Agents

Fabric Softeners

Floor Wax Emulsions

Grouts

Household and Institutional Products, Dishwashing Liquids

Hydraulic Fluids

Industrial Preservative (In-can Preservative)

Inks

Liquid Detergents

Liquid Products (Unspecified)

Metalworking Cutting Fluids
Page 26 of 40

Metal Working Fluids

Mineral Slurries

Paints

Paints (Latex)

Pigment Slurries

Polishes

Resin Emulsions

Sealants

Spackling

Surfactants (Anionic, Nonionic Amphoteric and Cationic Surfactants)

Wallboard Joint Compound

Industrial processes and water systems

Oilfield Water Systems 

Subsurface Injection Water

Secondary Oil Recovery Injection Water

Oilfield and Gas Water Injection Systems

Oil Recovery Drilling Mud

Oil Recovery Packer Fluid

Table 3. Target Pests

Pest Name

Deterioration/Spoilage Bacteria

Aerobic slime-forming bacteria, Pseudomonas sp.

Slime-Forming Bacteria

Anaerobic Sulfate-Reducing Bacteria, Desulfovibrio desulfuricans

Iron-oxidizing bacteria, Gallionella sp.

Antimicrobial
Page 27 of 40

Appendix B. Environmental Fate Guideline Study Justifications

Study Title: Activated Sludge Sorption Isotherm

Guideline Number: 835.1110

Test Substance: AMP

Rationale for Requiring the Data

Data from this study are needed to determine the sorption potential of activated sludge for the removal 

of specific chemical compounds in biological wastewater treatment plants (WWTPs). No data is 

currently available. If the chemical is not sorbed or biodegraded, then it would pass through a 

biological treatment system unaffected, potentially contaminating surface and drinking waters where it 

may then have the potential to adversely affect non-target organisms. EPA needs activated sludge 

sorption study data to assess the distribution of the antimicrobial chemical among the solid, aqueous, 

and vapor phases of WWTPs. Specifically, this study identifies those chemicals which sorb to sludge 

biomass.

Practical Utility of the Data

1. How will the data be used? 

The data will be used to assess removal of the antimicrobial as a result of sorption to activated sludge. 

Percent removal via sorption to activated sludge and percent removal via biodegradation are used to 

determine overall removal of the antimicrobial during wastewater treatment. Overall removal during 

wastewater treatment is a key input used to determine concentrations of the antimicrobial in surface water 

immediately downstream of wastewater treatment plants. The concentrations of antimicrobial pesticide 

immediately downstream of wastewater treatment plants are used to assess exposure and risk to non-target 

endangered and non-endangered species. Exposure data are integral parts of the risk equation for 

determining the impact of pesticides to beneficial nontarget organisms through direct exposure from their 

food sources and habitat.

In addition, the data will be used to determine whether or not additional studies and/or label restrictions are 

needed. If the data indicate that the chemical does not sorb to sludge and instead partitions more readily to 

water and that the chemical does not biodegrade to an appreciable extent then the chemical has the potential 

to pass through the WWTP and therefore could be discharged in to the aquatic environment. This 

determination could trigger further data requirements to assess the chemical’s impact upon release. If the 

data indicates relatively high potential to sorb to sludge, a screening assessment of potential exposure to 

ecological organisms as a result of biosolids use and disposal would be performed.

2. How could the data impact the Agency’s future decision-making?

If the data show that removal of the chemical during wastewater treatment is negligible, then the risk 

assessments for this chemical would reflect the magnitude of potential risk derived from this chemical’s 

negligible removal. The risk assessment may result in the Agency requiring label restrictions that would be 

necessary for the products to meet the “no unreasonable adverse effects” requirements of FIFRA (e.g., 

changes to the directions for disposal).

In addition, EPA is required by section 7(a)(2) of the ESA to ensure that any action it authorizes or takes 

“...is not likely to jeopardize the continued existence of any endangered or threatened species or result in 

the destruction or adverse modification of critical habitat” and to use the best scientific data available” in 

carrying out this obligation. The data EPA intends to call in are necessary to inform the determination 

required by the ESA as to whether continued registration of a pesticide is not likely to jeopardize the 

species or its critical habitat. Absent this data EPA may not be able to conclude that this pesticide will not 

harm endangered species and may therefore need to consider other limitations on the use of the pesticide in 

order to fulfill the Agency’s statutory obligations under the ESA. The lack of these data will limit the 

flexibility that the Agency and registrants have in coming into compliance with the ESA and could result in 

use restrictions which are unnecessarily severe. 
Page 28 of 40

Study Title: Aerobic Aquatic Metabolism

Guideline Number: 835.4300

Test Substance: AMP

Rationale for Requiring the Data

Aerobic aquatic metabolism data is needed to conduct the environmental fate assessment to support the 

DMO uses in consumer household and industrial cleaning products, material preservative and industrial 

slimicide uses. Acceptable data on the aerobic aquatic metabolism of AMP in two-sediment systems are 

required. The data is not currently available. The Agency has limited understanding of how AMP behaves 

in aerobic aquatic environments after discharge to receiving water. The purpose of aerobic aquatic 

metabolism study is to determine the nature and extent of microbial degradation under aerobic conditions in 

receiving water/sediment systems during the dispersal of the biocide throughout the aquatic environment, 

and to characterize the formation and decline of degradates. This information will determine the 

persistence and concentrations of AMP over time in representative aerobic water/sediment systems. The 

results of the study will indicate the potential for AMP to contaminate the aquatic environment since 

biocide residues may be taken up by the sediment biota and passed on to other parts of the aquatic food 

web. Data are needed for two sediment-water systems conducted (one each) at neutral and acidic pHs.

Practical Utility of the Data

1. How will the data be used?

The data would establish the significance of aerobic aquatic microbial degradation of AMP as a route of 

degradation and identify, if possible, the degradation products formed that may adversely affect non-target 

organisms and may contaminate water and food sources of aquatic organisms. The data would also help 

establish the aerobic aquatic aerobic half-life of AMP in water/sediment systems, and possibly it’s 

degradates, and assist in developing a degradation pathway.

2. How could the data impact the Agency’s future decision-making?

The results of this study would indicate the nature and extent of formation and decline under aerobic 

aquatic conditions of AMP and it’s degradates that may be taken up by sediment biota and passed on to 

other parts of the aquatic food web, and facilitates assessment of potential disposal problems. The study 

helps to determine the degradation rate (half-life) of AMP in the presence of microorganisms in different 

natural water/sediment systems and establishes what metabolites (degradates) are formed under aerobic 

(oxygen-rich) conditions in the laboratory. If no acceptable aerobic aquatic metabolism data is available 

for AMP, it would be assumed to be stable to aerobic metabolism and we would not know if the chemical 

breaks down leading to reduced risk to human health or the environment or we would not know if more 

toxic degradates are formed leading to increased risk to human health or the environment. 
Page 29 of 40

Study Title: Anaerobic Aquatic Metabolism

Guideline Number: 835.4400

Test Substance: AMP

Rationale for Requiring the Data

Anaerobic aquatic metabolism data is needed to conduct the environmental fate assessment is needed to 

conduct the environmental fate assessment to support the DMO uses in consumer household and industrial 

cleaning products, material preservative and industrial slimicide uses. Acceptable data on the anaerobic 

aquatic metabolism of AMP in two-sediment systems are required. The data is not currently available. The 

Agency has limited understanding of how AMP behaves in anaerobic aquatic environments after discharge 

to receiving water. The purpose of an anaerobic aquatic metabolism study is to determine the nature and 

extent of microbial degradation under anaerobic conditions in water/sediment systems during the dispersal 

of the biocide throughout the aquatic environment, and to characterize the formation and decline of 

degradates. This information will determine the persistence and concentrations of AMP and potential 

degradates over time in representative anaerobic water/sediment systems. The results of the study will 

indicate the potential for AMP to contaminate the aquatic environment since biocide residues may be taken 

up by the sediment biota and passed on to other parts of the aquatic food web. Additionally, anaerobic 

conditions are more likely to prevail where biocides are found in aquatic environments than in strictly 

terrestrial environments. Data are needed for two sediment-water systems conducted (one each) at neutral 

and acidic pHs.

Practical Utility of the Data

1. How will the data be used?

Anaerobic aquatic metabolism data will facilitate a better understanding of the fate of AMP residues in 

water and sediment. The data would establish the significance of anaerobic aquatic microbial degradation 

of AMP as a route of degradation and identify, if possible, the degradation products formed that may 

adversely affect non-target organisms and may contaminate water and food sources of aquatic organisms. 

The data would also help establish the anaerobic aquatic microbial half-life of AMP in water/sediment 

systems, and possibly it’s degradates, and assist in developing a degradation pathway.

2. How could the data impact the Agency’s future decision-making?

The results of this study would indicate the nature and extent of formation and decline under anaerobic 

aquatic conditions of AMP and it’s degradates that may be taken up by sediment biota and passed on to 

other parts of the aquatic food web, and would facilitate assessment of potential disposal problems. The 

study helps to determine the degradation rate (half-life) of MBT in the presence of microorganisms in 

different natural water/sediment systems and establishes what metabolites (degradates) are formed under 

anaerobic (oxygen-poor) conditions in the laboratory. If the data indicate that degradation in anaerobic 

conditions occurs rapidly in acidic and or neutral aquatic systems and produces nontoxic transformations 

products, then the Agency could potentially determine that AMP residues of concern do not persist in these 

systems. If data indicate that degradation is not appreciable in aquatic systems or that transformation 

products are similar or higher toxicity than the parent compound, then the Agency could conclude that 

AMP residues of concern persist in aquatic systems under anaerobic conditions. In the absence of the 

requested data, AMP anaerobic aquatic metabolism half-lives will be conservatively assumed to be stable 

across the environmental pH range. 
Page 30 of 40

Study Titles: Ready Biodegradability; Porous Pot Test; or Simulation Test – Aerobic Sewage 

Treatment: A. Activated Sludge Units; or Simulation Tests to Assess the Biodegradability of 

Chemicals Discharged to Wastewater (particularly Biodegradation in Activated Sludge)

Guideline Numbers: 835.3110; 835.3220; 835.3240; or 835.3280, respectively

Test Substance: AMP

Rationale for Requiring the Data

For antimicrobial chemicals that go down-the-drain and reach a WWTP, as part of its screening-level 

environmental fate assessment, EPA will analyze the potential impact of the antimicrobial chemical on the 

microorganisms in the biological treatment processes of a WWTP. Biodegradation is an important 

environmental pathway in which the antimicrobial is broken down by bacteria. These study results supply 

information on the rate of biological breakdown and the completeness of the degradation to carbon dioxide 

and water. A Ready Biodegradability study would allow the Agency to determine whether or not the 

chemical achieves ‘‘pass levels’’ for ready biodegradability (e.g., 70% removal of dissolved organic 

carbon). The results of the Activated Sludge Respiration Inhibition Test (ASRI) determine which of these 

four biodegradation tests are required. If the ASRI test EC50 is less than or equal to 20 mg/L, then either 

the (i) Biodegradation in Activated Sludge Study or (ii) Simulation Test – Aerobic Sewage Treatment: A. 

Activated Sludge Units or the (iii) Porous Pot Test is required. If the ASRI test EC50 is greater than 20 

mg/L, then the applicant must choose either: (i) Ready Biodegradability or (ii) Biodegradation in Activated 

Sludge or (iii) Simulation Test – Aerobic Sewage Treatment: A. Activated Sludge Units or (iv) the Porous 

Pot Test. If the antimicrobial passes the Ready Biodegradability study, then no further testing is required. 

If, however, the antimicrobial fails the Ready Biodegradability study, then the (i) Biodegradation in 

Activated Sludge or (ii) Simulation Test – Aerobic Sewage Treatment: A. Activated Sludge Units, or (iii) 

the Porous Pot study is required.

Practical Utility of the Data

1. How will the data be used?

The data from a biodegradation study will be used to determine the percent removal of the antimicrobial as 

a result of biodegradation of the antimicrobial by activated sludge microorganisms. Percent removal via 

biodegradation is a key input used to determine concentrations of the antimicrobial in surface water 

immediately downstream of wastewater treatment plants. The concentrations of antimicrobial pesticide 

immediately downstream of wastewater treatment plants are used to assess exposure and risk to non-target 

endangered and non-endangered species. Exposure data are integral parts of the risk equation for 

determining the impact of pesticides to beneficial non-target organisms through direct exposure from their 

food sources and habitat.

In addition, the data will be used to determine whether or not additional studies and/or label restrictions 

are needed. If the chemical does not achieve a ‘‘pass level’’ for ready biodegradability, then the Agency 

would determine that the chemical has the potential to pass through the WWTP and therefore may be 

discharged in to the aquatic environment potentially resulting in exposure to non-target species. This 

determination would trigger further data requirements to assess the chemical’s impact on the aquatic 

environment upon release.

2. How could the data impact the Agency’s future decision-making?

If the chemical is found to be readily biodegraded, then activated sludge microorganisms would be 

identified as highly biodegradable (90% removal via biodegradation). This result would be used in 

conjunction with wastewater treatment plant influent volume and measurement endpoints for aquatic 

organisms to determine concentrations of antimicrobial pesticide downstream of wastewater treatment 

plants. If high inhibition of activated sludge microorganisms (i.e., EC50 less than or equal to 20 mg/L) is 

determined in an activated sludge respiration inhibition test, then higher-tiered wastewater treatment plant 

(WWTP) biodegradation studies and/or an activated sludge sorption isotherm study may be triggered. If 

results of higher-tier WWTP biodegradation tests indicate low or negligible removal by biodegradation, the 
Page 31 of 40

risk assessments for this chemical would reflect the magnitude of potential risk derived from the chemical’s 

lack of biodegradability. The risk assessment may result in the Agency requiring label restrictions that 

would be necessary for the products to meet the “no unreasonable adverse effects” requirements of FIFRA 

(e.g., changes to the directions for disposal).

In addition, EPA is required by section 7(a)(2) of the ESA to ensure that any action it authorizes or takes 

“...is not likely to jeopardize the continued existence of any endangered or threatened species or result in 

the destruction or adverse modification of critical habitat” and to use the best scientific data available” in 

carrying out this obligation. The data EPA intends to call in are necessary to inform the determination 

required by the ESA as to whether continued registration of a pesticide is not likely to jeopardize the 

species or its critical habitat. Absent this data EPA may not be able to conclude that this pesticide will not 

harm endangered species and may therefore need to consider other limitations on the use of the pesticide in 

order to fulfill the Agency’s statutory obligations under the ESA. The lack of these data will limit the 

flexibility that the Agency and registrants have in coming into compliance with the ESA and could result in 

use restrictions which are unnecessarily severe.
Page 32 of 40

Appendix C: Ecological Guideline Study Justifications

Study Title: Aquatic Invertebrate Acute Toxicity Test, Freshwater Species

Guideline Number: 850.1010

Test Substance: Degradation Product: AMP

Rationale for Requiring the Data

No data are available to assess the potential acute lethal risks of the major toxic degradation product, 

AMP, to freshwater invertebrates. Aquatic invertebrate data for AMP are necessary because freshwater 

invertebrates may be exposed based on DMO’s use patterns, fate, and monitoring data. DMO is used in 

metal working fluids, oilfield water systems, oilfield drilling muds and workover and completion fluids, 

and consumer, household and industrial products which can result in discharge of DMO and its major 

degradate, AMP to surface waters. The requested data would allow EPA to estimate risks to freshwater 

invertebrates from exposure to AMP, including defining an action area for endangered species. 

Practical Utility of the Data 

1. How will the data be used? 

These data are needed for a registration review decision and for an endangered species assessment, which 

will be conducted as part of that decision. The freshwater invertebrate acute study data would allow the 

Agency to analyze acute lethal effects to freshwater invertebrates from acute exposures due to DMO’s use 

patterns and fate. The effects data with the degradate would be used to determine the likelihood that the 

acute risks can potentially impact aquatic communities, either by direct effects on invertebrates or by 

indirect effects by reducing food resources to species that rely on invertebrates as a food resource.

2. How could the data impact the Agency’s future decision-making?

Risk estimates (i.e., risk quotients or concentration of concern values) cannot be evaluated without these 

data. In the absence of data, if an acute toxicity test is available for DMO, the toxicity of the degradate 

will be assumed to be equivalent to that of the parent, DMO. Otherwise, acute risks to freshwater 

invertebrates would be presumed; the Agency would have to assume that DMO and its degradate “may 

affect” endangered freshwater invertebrates directly (and endangered species from other taxa indirectly). 

The lack of these data will limit the flexibility the Agency and registrants have in addressing risks to nonlisted and listed species and in coming into compliance with the Endangered Species Act, and could result 

in use restrictions or withdrawal of uses for DMO which may otherwise be avoided, or which are 

unnecessarily severe.

Study Title: Estuarine/marine invertebrate acute toxicity test one crustacean species

Guideline Number: 850.1035

Test Substance: Degradation Product AMP

Rationale for Requiring the Data

A crustacean (mysid) is one of two representative saltwater species used to evaluate acute effects for all 

estuarine/marine invertebrates. No acceptable acute study for AMP with an estuarine/marine crustacean 

species has been submitted. No acceptable acute studies for the major degradate, AMP, with an 

estuarine/marine crustacean species. An acute test using a crustacean is required because this major 

degradate is expected to reach estuarine/marine environments based on DMO use patterns, and fate data. 

In the absence of data, the degradate would be assumed to be as toxic as the supplemental study results 

with DMO. However, this will introduce a large degree of uncertainty into the assessment as the 

concentration of DMO, AMP, and other degradates is unknown in the study and could potentially result 

in an underestimation of risk from continuous exposure from discharges from WWTPs.

Practical Utility of the Data

1. How will the data be used?

These data are needed for a registration review decision and for an endangered species assessment, which 

will be conducted as part of that decision. The estuarine/marine invertebrate acute studies allow the 
Page 33 of 40

Agency to analyze acute lethal effects to estuarine/marine invertebrates from acute exposures due to BTS 

use. The effects data would be used to determine the likelihood that the acute risks can potentially 

impact aquatic communities, either by direct effects on invertebrates or by indirect effects by reducing 

food resources to species that rely on invertebrates as a food resource.

2. How could the data impact the Agency’s future decision-making?

In the absence of acute mysid data, acute risks to marine/estuarine invertebrates would be calculated 

based on supplemental DMO data alone. But there would be uncertainty in whether the calculated risk is 

an underestimate, and the degree of underestimation is unknown. Decisions may be made incorrectly 

based on these results.

Study Title: Estuarine/Marine Mollusk Study—Either a Shell Deposition or an Embryo\Larvae 

Study

Guideline Number: 850.1025 or 850.1055, respectively

Test Substance: Degradation Product AMP

Rationale for Requiring the Data

A mollusk is a representative saltwater species used to evaluate acute effects for all estuarine/marine 

invertebrates. No acceptable acute studies for the major degradate, AMP, with an estuarine/marine 

mollusk has been submitted. An acute test using an estuarine/marine mollusk species is required because 

this major degradate is expected to reach estuarine/marine environments based on DMO use patterns, and 

fate data. A mollusk study is also required because it tentatively appears likely to be the most sensitive of 

all aquatic organisms, both freshwater and estuarine/marine based on the acceptable DMO mollusk study 

and the supplemental freshwater fish and invertebrate data. The mode-of-action to mollusks may be 

different from that of crustaceans and fish, and therefore any DMO: AMP ratio or factor derived from 

crustacean or fish data may underestimate the degradate toxicity to mollusks. In the absence of data, the 

degradate AMP would be assumed to be as toxic as the parent, DMO, for the mollusk.

Practical Utility of the Data

1. How will the data be used?

These data are needed for a registration review decision and for an endangered species assessment, which 

will be conducted as part of that decision. The estuarine/marine invertebrate acute studies allow the 

Agency to analyze acute lethal effects to estuarine/marine invertebrates from acute exposures due to 

DMO use. The effects data would be used to determine the likelihood that the acute risks can potentially 

impact aquatic communities, either by direct effects on invertebrates or by indirect effects by reducing 

food resources to species that rely on invertebrates as a food resource. 

2. How could the data impact the Agency’s future decision-making?

In the absence of acute mollusk data, acute risks to marine/estuarine mollusks would be calculated 

assuming that the degradate is as toxic as the parent, and potentially be based on the DMO mollusk data

which may result in underestimation of risk.

Study Title: Fish Acute Toxicity Test, Freshwater Species, Most Sensitive of the DMO Species—

Bluegill Sunfish

Guideline Number: 850.1075

Test Substance: Degradation Product: AMP

Rationale for Requiring the Data

No data are available to assess the potential acute lethal risks of the major toxic degradation product,

AMP, to freshwater fish. Fish acute data for AMP are necessary because freshwater fish may be exposed 

based on DMO’s use pattern, fate, and monitoring data. Only data for the most sensitive of the TGAI 
Page 34 of 40

species is required, as this should also be the most sensitive species for the degradate. DMO is used in 

metal working fluids, oilfield water systems, oilfield drilling muds and workover and completion fluids, 

and consumer, household and industrial products which can result in discharge of DMO and its major 

degradate, AMP, to surface waters. The requested data would allow EPA to estimate risks to freshwater 

fish from exposure to AMP, including defining an action area for endangered species. 

Practical Utility of the Data

1. How will the data be used?

These data are needed for a registration review decision and for an endangered species assessment, which 

will be conducted as part of that decision. The freshwater fish acute study data would allow the Agency 

to analyze acute lethal effects to freshwater fish from acute exposures due to DMO use and fate. The 

effects data with the degradate would be used to determine the likelihood that the acute risks can 

potentially impact aquatic communities, either by direct effects on fish or by indirect effects by reducing 

food resources to species that rely on fish as a food resource.

2. How could the data impact the Agency’s future decision-making?

Risk estimates (i.e., risk quotients or concentration of concern values) cannot be evaluated without these 

data. In the absence of data, if an acute toxicity test is available for DMO the toxicity of the degradate 

will be assumed to be equivalent to that of the parent DMO otherwise if no TGAI or degradate data are

available acute risks to freshwater fish would be presumed; the Agency would have to assume that DMO

and its degradate “may affect” endangered freshwater fish directly (and endangered species from other 

taxa indirectly). The lack of these data will limit the flexibility the Agency and registrants have in 

addressing risks to non-listed and listed species and in coming into compliance with the Endangered 

Species Act, and could result in use restrictions or withdrawal of uses for DMO which may otherwise be 

avoided, or which are unnecessarily severe.

Study Title: Fish Acute Toxicity Test, Estuarine/Marine Species

Guideline Number: 850.1075

Test Substance: Degradation Product: AMP

Rationale for Requiring the Data

No data are available to assess the potential acute lethal risks of the major toxic degradation product,

AMP, to estuarine/marine fish. Fish acute data for AMP are necessary because estuarine/marine fish may 

be exposed based on DMO’s use pattern, and fate data. DMO is used in metal working fluids, oilfield 

water systems, oilfield drilling muds and workover and completion fluids, and consumer, household and 

industrial products which can result in discharge of DMO’s major degradate, AMP, to surface waters. 

The requested data would allow EPA to estimate risks to estuarine/marine fish from exposure to AMP, 

including defining an action area for endangered species. 

Practical Utility of the Data

1. How will the data be used?

These data are needed for a registration review decision and for an endangered species assessment, which 

will be conducted as part of that decision. The estuarine/marine acute study data would allow the Agency 

to analyze acute lethal effects to estuarine/marine fish from acute exposures due to DMO use and fate. 

The effects data with the degradate would be used to determine the likelihood that the acute risks can 

potentially impact aquatic communities, either by direct effects on fish or by indirect effects by reducing 

food resources to species that rely on fish as a food resource.

2. How could the data impact the Agency’s future decision-making?

Risk estimates (i.e., risk quotients or concentration of concern values) cannot be evaluated without these 

data. In the absence of data, if an acute toxicity test is available for DMO the toxicity of the degradate 

will be assumed to be equivalent to that of the parent DMO otherwise if no TGAI or degradate data are 
Page 35 of 40

available acute risks to estuarine/marine fish would be presumed; the Agency would have to assume that 

DMO and its degradate “may affect” endangered estuarine/marine fish directly (and endangered species 

from other taxa indirectly). The lack of these data will limit the flexibility the Agency and registrants 

have in addressing risks to non-listed and listed species and in coming into compliance with the 

Endangered Species Act, and could result in use restrictions or withdrawal of uses for DMO which may 

otherwise be avoided, or which are unnecessarily severe.

Study Title: Aquatic Invertebrate Life-Cycle, Freshwater Species

Guideline Number: 850.1300

Test Substance: Degradation Product: AMP

Rationale for Requiring the Data

No chronic life cycle toxicity data for a freshwater invertebrate species has been submitted for the major 

degradate, AMP. Chronic aquatic invertebrate data for this degradate are necessary because based on 

DMO’s use patterns, fate, and monitoring data freshwater invertebrates may be repeatedly exposed to 

DMO and its major degradate, AMP. DMO is used in metal working fluids, oilfield water systems, oilfield 

drilling muds and workover and completion fluids, and consumer, household and industrial products which 

can result in discharge of DMO and its major degradate, AMP to surface waters. The requested data would 

allow the Agency to estimate chronic risks to freshwater invertebrates from exposure to this degradate, 

including defining an action area for endangered species. Without these data, the Agency would have to 

assume that the degradate is at least as toxic as the parent, DMO. However, there is no chronic data for the 

parent either, so without these data, the Agency is unable to evaluate the potential risks to freshwater 

invertebrates associated with chronic exposure to DMO or its degradate. The Agency would have to 

presume chronic risk to listed and non-listed freshwater invertebrates, but would not be able to quantify the 

risk.

Practical Utility of the Data

1. How will the data be used? 

These data are needed for a registration review decision and for an endangered species assessment, which 

will be conducted as part of that decision. The aquatic invertebrate life-cycle study would allow the 

Agency to analyze chronic effects, including effects on reproductive success, survival and growth, to 

freshwater invertebrates due to exposure to the degradate, AMP. The effects data would be used to 

determine the likelihood that the chronic risks can potentially impact aquatic communities, either by direct 

effects on invertebrates or by indirect effects on fish by reducing their food sources. 

2. How could the data impact the Agency’s future decision-making?

In the absence of data, the Agency would have to assume that the degradate is at least as toxic as the parent, 

DMO. However, there is no chronic data for the parent either, so without these data, the Agency is unable 

to evaluate the potential risks to freshwater invertebrates associated with chronic exposure to DMO or its 

degradate. The lack of these data will limit the flexibility the Agency and registrants have in addressing 

risks to non-listed and listed species and in coming into compliance with the Endangered Species Act, and 

could result in use restrictions or withdrawal of uses for DMO which may otherwise be avoided, or which 

are unnecessarily severe.

Study Title: Aquatic Invertebrate Life-Cycle, Estuarine/Marine Species

Guideline Number: 850.1350

Test Substance: Degradation Product: AMP

Rationale for Requiring the Data

No chronic life cycle toxicity test for an estuarine/marine invertebrate species has been submitted for the 

degradate, AMP. Chronic aquatic invertebrate data for this degradate is necessary because based on 
Page 36 of 40

DMO’s use pattern, and fate data estuarine/marine invertebrates may be repeatedly exposed to DMO’s

major degradate, AMP. DMO is used in metal working fluids, oilfield water systems, oilfield drilling muds 

and workover and completion fluids, and consumer, household and industrial products which can result in 

discharge of DMO and its major degradate, AMP to surface waters. Without the estuarine/marine lifecycle data for the degradate, the Agency is unable to evaluate the potential chronic risks to estuarine/marine 

invertebrates associated with chronic exposure to the degradate. The Agency would have to presume 

chronic risk to listed and non-listed estuarine/marine invertebrates, but would not be able to quantify the 

risk.

Practical Utility of the Data

1. How will the data be used? 

The aquatic invertebrate life-cycle study would allow the Agency to analyze chronic effects, including 

effects on reproductive success, survival and growth, to estuarine/marine invertebrates. The effects data 

would be used to determine the likelihood that the chronic risks can potentially impact aquatic 

communities, either by direct effects on invertebrates or by indirect effects to organisms preying on 

estuarine/marine invertebrates. 

2. How could the data impact the Agency’s future decision-making?

In the absence of data, chronic risks would be presumed to estuarine/marine invertebrates under chronic 

exposure conditions. The lack of these data will limit the flexibility the Agency and registrants have in 

addressing risks to non-listed and listed species and in coming into compliance with the Endangered 

Species Act, and could result in use restrictions or withdrawal of uses for DMO which may otherwise be 

avoided, or which are unnecessarily severe.

Study Title: Fish Early-life Stage Toxicity Test, Freshwater Species using Bluegill Sunfish the more 

sensitive of the acute tests with DMO

Guideline Number: 850.1400

Test Substance: Degradation Product: AMP

Rationale for Requiring the Data

No fish early-life stage toxicity test for the major degradate, AMP, has been submitted. The fish early-life 

stage toxicity test provides the lethal and sublethal effects of a test substance on fish species. Chronic 

aquatic invertebrate data for this degradate are necessary because based on DMO’s use pattern, fate, and 

monitoring data, freshwater invertebrates may be repeatedly exposed to DMO and its major degradate, 

AMP. DMO is used in metal working fluids, oilfield water systems, oilfield drilling muds and workover 

and completion fluids, and consumer, household and industrial products which can result in discharge of 

DMO and its major degradate, AMP to surface waters. The requested data would allow the Agency to 

estimate chronic risks to freshwater fish from exposure to this degradate, including defining an action area 

for endangered species. Without these data, the Agency is unable to evaluate the potential risks to 

freshwater fish and aquatic-phase amphibians (for which fish serve as surrogates) associated with chronic 

exposure to the degradate. If the test is not conducted with the most acutely sensitive species, an acute 

toxicity test for the species used in the early life stage test needs to be conducted to allow calculation of 

an acute-to-chronic ratio for use in predicting an early life stage result for the most acutely sensitive 

species.
Page 37 of 40

Practical Utility of the Data

1. How will the data be used? 

The data from the fish early life stage test will be used to estimate the chronic risks to freshwater fish and 

amphibians associated with chronic exposures to DMO and its degradate. The data will reduce 

uncertainties associated with potential risks to freshwater fish and amphibians thereby facilitating sound 

environmental management of natural resources, particularly, freshwater fisheries. 

2. How could the data impact the Agency’s future decision-making?

In the absence of data, the toxicity of the degradate would be assumed to be the same as that of the parent, 

if chronic data for the parent was submitted, or if these data are not available either chronic risks would be

presumed to freshwater fish/amphibians under chronic exposure conditions. The lack of these data will 

limit the flexibility the Agency and registrants have in addressing risks to non-listed and listed species 

and in coming into compliance with the Endangered Species Act, and could result in use restrictions or 

withdrawal of uses for DMO which may otherwise be avoided, or which are unnecessarily severe.

Study Title: Seedling emergence Tier II

Test Species: Rice, Oryza sativa

Guideline Number: 850.4225

Test Substance: Degradation Product: AMP

Application method: Homogenously mixed into support media

Unit of Expression: milligrams per kilogram of bulk support media (dry wt)

Rationale for Requiring the Data

No seedling emergence and growth toxicity data for a rooted emergent vascular plant has been submitted

for DMO or its major degradate. Based on the fate of DMO, it is not expected to be persistent in the 

water column or sediment. However, the major degradate is more persistent and may sorb onto organic 

and inorganic particles in water and deposit them in sedimentary areas such as lakes, and freshwater and 

saltwater marshes. Uses of DMO in metal working fluids, oilfield water systems, oilfield drilling muds 

and workover and completion fluids, and consumer, household and industrial products are expected to 

lead to exposure of wetland plants due to transportation, and deposition of AMP sorbed onto particles in 

the waste stream from use sites. Without this data, the Agency is unable to evaluate the potential risks to 

rooted vascular emergent plants associated with exposure to AMP. In the study, a minimum of four 

replicates are necessary to allow a nonparametric statistical analysis, if the resulting data fail normality or 

homogeneity of variance assumptions.

Practical Utility of the Data

1. How will the data be used?

These data are needed for a registration review decision and for an endangered species assessment, which 

will be conducted as part of that decision. Emergent wetland plants, in association with soil or sediments, 

determine the structure and function of wetlands; they provide habitat in the form of nursery areas and 

cover for wildlife, and regulate the temperature and flow of water. The emergent vascular plant study

would allow the Agency to analyze to a critical component of the structure and function of an aquatic 

ecosystem. A toxicity study on an emergent vascular plant species is used to establish a dose response 

relationship of DMO with in terms of yield, growth rate, and area under the growth curve. The effects 

data would be used to determine the likelihood that losses to emergent plants will occur and that such 

losses would indirectly lead to loss of other aquatic organisms through impacts such as loss of a food 

resource, habitat, or habitat quality. 

2. How could the data impact the Agency's future decision-making?

In the absence of data, risks to emergent aquatic plants could not be calculated. Therefore, until 

additional data become available, risks to emergent vascular plants (both Federally-listed and non-listed 
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species) will be assumed in future DMO risk assessments. The lack of these data will limit the flexibility 

the Agency and registrants have in addressing risks to non-listed and listed species and in coming into 

compliance with the Endangered Species Act, and could result in use restrictions or withdrawal of uses 

for DMO which may otherwise be avoided, or which are unnecessarily severe.

Study Title: Aquatic Plant Growth, Floating Vascular Species (Lemna sp.), Tier II

Guideline Number: 850.4400

Test Substance: Degradation Product: AMP

Rationale for Requiring the Data

No non-rooted vascular aquatic plant toxicity data has been submitted for the major degradate AMP. 

DMO is used in metal working fluids, oilfield water systems, oilfield drilling muds and workover and 

completion fluids, and consumer, household and industrial products which can result in discharge of 

DMO and its major degradate, AMP to surface waters. The requested data would allow the Agency to 

estimate risks to aquatic plants from exposure to AMP, including defining an action area for endangered 

species.

Practical Utility of the Data

1. How will the data be used?

These data are needed for a registration review decision and for an endangered species assessment, which 

will be conducted as part of that decision. Mats of floating non-rooted aquatic plants provide habitat for 

small invertebrates, food and shelter for fish and amphibians, and food for waterfowl and marsh birds. 

The floating vascular aquatic plant study would allow the Agency to evaluate effects to a critical 

component of the structure and function of the aquatic plant community. A toxicity study on a non-rooted 

vascular aquatic plant species is used to establish a dose response relationship of AMP with effects to 

non-rooted aquatic plants in terms of yield, growth rate, and area under the growth curve. The effects 

data would be used to determine the likelihood that losses to non-rooted aquatic vascular plants will occur 

and that such losses would indirectly lead to loss of other aquatic organisms through impacts such as loss 

of a food resource, habitat, or habitat quality.

2. How could the data impact the Agency's future decision-making?

In the absence of data, the toxicity of the degradate would be assumed to be the same as that of the parent, 

if data for the parent was submitted, or if this data are not available either risks would be presumed for 

listed and nonlisted aquatic plants. The lack of these data will limit the flexibility the Agency and 

registrants have in addressing risks to non-listed and listed species and in coming into compliance with 

the Endangered Species Act, and could result in use restrictions or withdrawal of uses for DMO which 

may otherwise be avoided, or which are unnecessarily severe.

Study Title: Algal Toxicity, 4 species, Tier II

Guideline Number: 850.5400

Test Substance: Degradation Product: AMP

Rationale for Requiring the Data

No nonvascular aquatic plant toxicity data has been submitted for the major degradate AMP. Uses of 

DMO in metal working fluids, oilfield water systems, oilfield drilling muds and workover and completion 

fluids, and consumer, household and industrial products are expected to lead to exposure of aquatic 

organisms due to the repeated release and transport of DMO’s major degradate, AMP, from use sites into 

aquatic ecosystems. Without this degradate data, the Agency would have to presume risk to federally 

listed and non-listed non-vascular plants, but would not be able to quantify the risk.
Page 39 of 40

Practical Utility of the Data

1. How will the data be used?

These data are needed for a registration review decision and for an endangered species assessment, which 

will be conducted as part of that decision. The aquatic nonvascular plant study would allow the Agency

to analyze effects on primary production from exposure to the degradate. A toxicity study on nonvascular aquatic plant species is used to establish a dose response relationship of the degradate with 

primary productivity in terms of yield, growth rate, and area under the growth curve. The effects data 

would be used to determine the likelihood that losses to primary production will occur and that such 

losses would indirectly lead to loss of other aquatic organisms through impacts such as loss of a food 

resource, habitat, or habitat quality. 

2. How could the data impact the Agency's future decision-making?

In the absence of data, the toxicity of the degradate would be assumed to be the same as that of the parent, 

if data for the parent was submitted, or if this data are not available then risks would be presumed to listed 

and nonlisted aquatic plants. Therefore, until additional data become available, risks to aquatic nonvascular plants (both Federally-listed and non-listed species) will be assumed in future DMO risk 

assessments. The lack of these data will limit the flexibility the Agency and registrants have in 

addressing risks to non-listed and listed species and in coming into compliance with the Endangered 

Species Act, and could result in use restrictions or withdrawal of uses for DMO which may otherwise be 

avoided, or which are unnecessarily severe.

Guideline Number: 850.2100

Study Title: Acute avian oral toxicity

Test Substance: Degradation Product: AMP

Practical Utility of the Data

1) What is the value of the study?

The Agency currently does not have any acceptable acute avian oral toxicity data for AMP. This study 

would allow the Agency to categorize AMP as toxic or non-toxic to birds. If the avian acute oral LD50 is 

less than or equal to 100 mg a.i./kg, additional higher tier bird test would be needed.

2) How would the data be used?

This study would be used to evaluate the toxicity of AMP to non-target birds in terrestrial and aquatic 

ecosystems.

3) How could the data affect the risk assessment? 

Adverse effects to non-target birds in terrestrial and aquatic ecosystems may result in mitigation to protect 

species at risk.

4) What is triggering the need for this data?

Acute avian oral toxicity study is required to establish the toxicity of a pesticide to birds.
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Guideline Number: 850.6800; OECD 209

Study Title: Activated Sludge, Respiration Inhibition Test for Sparingly Soluble Chemicals; 

Activated Sludge Respiration Inhibition Test

Rationale for Requiring the Data

An activated sludge, respiration inhibition test (ASRI) is needed to identify whether this pesticide could 

harm activated sludge microorganisms found in biological wastewater treatment systems. The Agency 

will use these data to determine the potential impact of this chemical on waste water treatment plants 

(WWTPs) as a result of respiration inhibition of activated sludge microorganisms. This test is also 

necessary to enable EPA to establish correct concentrations for use in the biodegradability test, if that 

test is determined to be adequate for assessing biodegradation potential. Furthermore, the results of the 

Activated Sludge Respiration Inhibition Test (ASRI) determine which biodegradation test is required. If 

the ASRI test EC50 is less than or equal to 20 mg/L, then either the Biodegradation in Activated Sludge 

Study or the Porous Pot Test is required. If the ASRI test EC50 is greater than 20 mg/L, then the applicant 

must choose either: (i) Ready Biodegradability or (ii) Biodegradation in Activated Sludge or the Porous Pot 

Test. If the antimicrobial passes the ready biodegradability study, then no further testing is required. If, 

however, the antimicrobial fails the ready biodegradability study, then the Biodegradation in Activated 

Sludge or the Porous Pot study is required.

Practical Utility of the Data

1. How will the data be used?

The data will be used to assess potential adverse effects to activated sludge microorganisms. In addition, 

the data will be used to determine whether or not label restrictions are needed. The study will identify the 

inhibitory effect of this chemical on the treatment plant’s microorganisms’ respiration at different 

concentrations of the test substance and will identify the EC50, the effective concentration of the test 

substance at which the respiration rate is 50% of that shown by the control under conditions in this 

guideline. The data will also determine suitable non-inhibitory concentrations to be used in 

biodegradability tests.

2. How could the data impact the Agency’s future decision-making?

If the data indicate a high degree of activated sludge respiration inhibition, a more rigorous test for 

biodegradation in wastewater treatment will be required than the ready biodegradability test. Also, if a 

high degree of respiration inhibition is demonstrated and biodegradation and/or sorption is indicated to be 

negligible, the Agency may require label restrictions or mitigation measures to insure that activated sludge 

microorganisms will not be adversely impacted.