Page 2 of 14

this assessment the Agency requires fate data such as hydrolysis, aqueous photolysis, 

modified activated sludge respiration inhibition, ready biodegradability, porous pot test, 

or simulation test. SHMG is practically non-toxic to avian species on an acute oral and 

subacute dietary basis; practically non-toxic to mammals on an acute oral basis; and 

practically non-toxic to freshwater fish and invertebrate. For the ecological risk 

assessment, including an endangered species assessment for all uses, the Agency requires 

the algal toxicity data.

Introduction 

Glycine, N-(hydroxymethyl)-monosodium salt (an N-methylol) is an alkaline 

preservative, also known as Sodium hydroxymethylglycinate (SHMG). It is a clear 

alkaline liquid with a mild characteristic odor. It is in a class of chemicals known as 

formaldehyde-releasing preservatives used in many commercially available products, 

including shampoos, conditioners, soaps, shower gels, moisturizers, body sprays, makeup 

remover, around-eye cream, moisturizer, anti-aging, styling gel/lotion, hair relaxer, baby 

wipes, room sprays, cleaning agents, and pesticides to help preserve them from bacterial 

or fungal growth. The first product containing SHMG as an active ingredient was 

registered in the United States on June 18, 1997 for use as an industrial use only 

preservative/microbiocide for use in aqueous compositions, such as liquid soaps, fabric 

cleaning & care products, water-based cleaning products, waterborne coatings, waterbased adhesives, printing supplies, polishes and textile emulsions. Currently there is only 

one end use product registered with SHMG as an active ingredient for the material 

preservative use listed in Table 1. A Reregistration Eligibility Decision (RED) has not 

been issued by EPA for SHMG because the initial registration date was after the 

November 1984, the mandated cutoff for initiation of the RED process. A RED was 

issued by EPA for Formaldehyde in June 20081

. 

Table 1. Registered Product of Sodium hydroxymethylglycinate 

Registration # Registration Name Company 

Name 

Formulation 

Type 

% of 

Active 

Ingredient 

57978-4 Suttocide A 50% Solution ISP 

Chemicals, 

LLC 

Ready-to-Use 

Solution

50 

EPA Reg. No. 57978-4 

Suttocide A 50% Solution 

A Broad Spectrum Preservative and Bocide. 

Active Ingredient: Sodium Hydroxymethylglycinate 50.0% 

Suttocide A 50% Solution is an industrial microbiocide for use in aqueous 

compositions, such as liquid soaps, fabric cleaning & care products, water-based cleaning 

 

1

http://www.epa.gov/pesticides/reregistration/REDs/formaldehyde-red.pdf
 Page 3 of 14

products, waterborne coatings, water-based adhesives, printing supplies, polishes and 

textile emulsions. 

Suttocide A 50% Solution is a biocidal agent used to inhibit the growth of bacteria 

and fungi. It is for indoor commercial and industrial use and is generally effective at 

concentrations of 0.1% to 0.5% (2 to 10 gallons of Suttocide A 50% Solution per 1,000 

gallons of the product being treated. This will provide 1,000 to 5,000 ppm of active 

ingredient). 

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

environmental fate, and ecotoxicity data for SHMG. The findings are summarized below. 

A. Product Chemistry Summary (50% TGAI Solution) 

Common Name: Glycine, N-(hydroxymethyl)-monosodium salt 

Chemical Names: Sodium hydroxymethylamino acetate 

 Sodium hydroxymethyl glycinate (SHMG)

Trade and Other Names: Suttocide A; Integra 44 

OPP Chemical Code: 128972 

CAS Registry Number: 70161-44-3

Case: 5030 

Chemical Family: Carboxylic acid salt

Molecular Formula: C3H6NNaO3

Molecular weight: 127.07

Molecular Structure: 

 

Color: Pale to clear yellow liquid. 

Physical State: Liquid. 

Odor: Mild characteristic odor of aromatic compound. 

Stability: Stable under normal conditions of handling, use and 

transportation. 

Oxidation/Reduction: Does not contain oxidizing or reducing agents. 

Flammability-Flash Point: Not flammable; Flash Point: 100°C (212°F). 

Explodability: Not applicable. Product is not potentially explosive.

Storage Stability: Stable under conditions of use and expected storage. 

Miscibility: Not applicable. Product is not an emulsifiable liquid 

intended to be diluted with petroleum distillates. 
 Page 4 of 14

Corrosion Characteristics: Minimally corrosive to steel.

Dielectric breakdown voltage: Not applicable. Product is not intended to be used 

around electrical equipment.

pH: 11-12 (1% solution). 

UV/Visible absorption: Not provided.

Viscosity: 21 cps @ 23°C

Melting point: Not applicable. Product is liquid. 

Boiling Point: 210°F 

Density: 1.28 – 1.3 

Specific Gravity: 1.28 @ 25oC 

Dissociation Constant: pKb - 8.41 

Log Ko/w or log P: Not required. Chemical is polor. 

Solubility: Soluble in water.

Vapor Pressure: 1.0 mmHg @ 20°C (water)

Enf. Analytical Method: Decomposition and Ion Chromatography.

Product Chemistry Summary (97% TGAI Powder created in the laboratory) 

Color: White to off-white free flowing powder. 

Physical State: Powder. 

Odor: None to a mild odor characteristic of aromatic 

compounds. 

Stability: Stable under normal conditions of use and storage. 

Oxidation/Reduction: Does not contain oxidizing or reducing agents. 

Flammability-Flash Point: Not applicable. Technical chemical is a powder and 

does not contain combustible liquids.

Explodability: Technical chemical is not potentially explosive. 
 Page 5 of 14

Storage Stability: Stable under conditions of use and expected storage. 

Miscibility: Not required. Technical chemical is not an 

emulsifiable liquid. 

Corrosion Characteristics: Not applicable. Technical chemical is a dry powder 

and is non-corrosive. 

Dielectric breakdown voltage: Not applicable. Product is not intended to be 

used around electrical equipment.

pH: 10.41 ± 0.08

UV/Visible absorption: Not provided.

Viscosity: Not required. Technical chemical is a powder. 

Melting point: On-set of decomposition at 80°C. Melting point at 

151°C. 

Boiling Point: Not required. Technical chemical is not a liquid. 

Density: Bulk Density: 0.58 g/ml.

Dissociation Constant: pKb - 8.41 carboxylic acid salt (-COO NA+); pKb ≥

- 11.0 secondary amine (-NH-) 

Log Ko/w or log P: Not required. Technical chemical is polor (97%). 

-6.19 (EPI Suite). 

Solubility: PAI in water ~1344 .4 ± 3 .9 g/L

Vapor Pressure: Not applicable. Powder is highly hygroscopic.

2.43 ×10-11 mm Hg (Source: EPI Suite). 

Henry's Law Constant: 1.81E-012 atm-m3/mole 25oC (Source: EPI Suite). 

Enforcement Analytical 

Method: Decomposition and Ion Chromatography. 

All product chemistry data requirements have been satisfied for the active 

ingredient SHMG. (Source: MRIDs 41980401, 41980402, 41980403, & 

41980003). 

B. Environmental Fate Summary 
 Page 6 of 14

SHMG is an aminoacid (glycine) derivative produced by the condensation 

reaction of the sodium salt of glycine with formaldehyde, in aqueous medium in a molar 

ratio of 1:1. SHMG is highly soluble in water. Maximum authorized concentration in 

pesticide and cosmetic products is 0.5%. In an aqueous solution, sodium hydroxymethyl 

glycinate is decomposed to release formaldehyde. One molecule of formaldehyde is 

formed by the decomposition of each molecule of sodium hydroxymethyl glycinate, as 

described below. The total free formaldehyde content in a product containing 0.5% 

sodium hydroxymethyl glycinate corresponds to 0.118%. The decomposition product of 

sodium hydroxymethyl glycinate, e.g. sodium glycinate cannot be considered harmful. 

SHMG 6RGLXPJO\FLQDWH )RUPDOGHK\GH

Formaldehyde releaser SHMG (Suttocide A 50%) is an aqueous solution that 

decomposes to sodium glycinate and then formaldehyde. No risk assessment was 

performed for SHMG at the time of the registration. The Agency has not received any 

guideline environmental fate studies on SHMG and fate studies are required to conduct 

an environmental fate assessment for material preservatives (including SHMG) that may 

potentially pass through waste water treatment plants (WWTPs) and may be discharged 

into terrestrial and aquatic environments. For this assessment the Agency anticipates 

needing those data outlined on page 10 of this document. 

Water Quality 

SHMG 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)2. In addition, no Total Maximum Daily Loads (TMDL) have been developed 

for SHMG, based on information provided at the Agency’s National Pesticide TMDL 

web site (searched April 7, 2011)3

. 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. 

 

2

 . http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885 3

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

ollutant_group_name=PESTICIDES
 Page 7 of 14

C. Ecological Effects Summary 

No ecological risk assessment was performed for SHMG at the time of the 

registration. SHMG is a formaldehyde-releaser. Available ecotoxicity guideline studies 

for SHMG and the formaldehyde degradate and the results are summarized in Tables 2 

and 3. The Agency's conclusions for the terrestrial and aquatic effects studies are as 

follows. 

a. Toxicity to Terrestrial Animals 

Birds, Acute and Subacute

SHMG is practically nontoxic to avian species on an acute oral and 

subacute dietary basis. 

Formaldehyde degradate: 37% ai formaldehyde is slightly toxic to avian 

species on an acute oral basis and practically non-toxic on a subacute dietary 

basis. 

Toxicity to Mammals 

SHMG is practically nontoxic to mammals on an acute oral basis. 

Formaldehyde degradate: Technical grade formaldehyde (37% a.i.) is 

moderately toxic to mammals on an acute oral basis. 

There is currently no 2-generation rat reproduction study for SHMG but in 

the human health scoping document it has been identified as a data gap. 

b. Toxicity to Aquatic Animals 

Freshwater Fish and Invertebrates 

SHMG is practically nontoxic to warm/cold freshwater fish and aquatic 

invertebrates. 

Formaldehyde degradate: 37% ai formaldehyde is slightly to practically 

nontoxic to freshwater fish and slightly toxic to freshwater invertebrates. 

c. Toxicity to Aquatic Plants 

Freshwater Algae 

No algal toxicity data have been submitted. For the ecological risk 

assessment, including an endangered species assessment for all uses, the 

Agency anticipates needing the algal toxicity data outlined on page 10 of 

this document. 
 Page 8 of 14

Table 2. Ecotoxicity Data Summary for Sodium hydroxymethyl glycinate 

MRID 

No. 

COMMON 

NAME 

TAXONOMIC 

NAME 

GUIDE 

LINE 

TEST 

TYPE 

% 

AI 

STUDY 

TIME 

DOSE 

TYPE 

TOXI 

CITY 

TOX 

LEVEL NOEL STUDY STATUS 

TOX 

CATEGORY 

Avian Acute Oral Toxicity 

41980404 Bobwhite 

quail 

Colinus 

virginianus 

850.2100 

(71-1) 

O 97 14 days LD50 >2250 mgk 486 Acceptable Practically 

nontoxic 

Avian Subacute Dietary Toxicity 

41980405 Mallard 

duck 

Anas 

platyrhynchos 

850.2200 

(71-2b) 

D 97 8 days LC50 >5620 ppm 5620 Acceptable Practically 

nontoxic 

41980406 Bobwhite 

quail 

Colinus 

virginianus 

850.2200 

(71-2a) 

D 97 8 days LC50 >5620 ppm 5620 Acceptable Practically 

nontoxic 

Freshwater Fish Acute Toxicity 

44105802 Rainbow 

trout 

Oncorhynchus 

mykiss 

850.1075 

(72-1) 

F 49.53 96 hr LC50 106 ppm 35 Acceptable Practically 

nontoxic 

44105803 Bluegill 

sunfish 

Lepomis 

macrochirus 

850.1075 

(72-1) 

F 49.53 96 hr LC50 75 ppm 40 Acceptable Slightly 

nontoxic 

Freshwater Invertebrate Acute Toxicity 

44105801 Water flea Daphnia 

magna

850.1010 

(72-2) 

F 49.53 48 hr EC50 39 ppm 15 Acceptable Slightly toxic 

Mammalian Acute Oral Toxicity

42484501 Rat ------ 81-1 ----- 50% 

soln. 

----- LD50

LD50 

LD50 

2300(M) 

2100(F) 

2100 

(combined) 

mg/kgbw ----- Acceptable Practically 

non-toxic (III) 

Mammalian Subchronic Oral Toxicity

41980429 SpragueDawleyRats ----- 82-1 ----- 50% 

soln 

28 days LOEL 640 mg/kgbw/day 160 Acceptable 

42005801 SpragueDawley Rat ----- 82-1 ----- 50% 

Soln. 

90 days LOEL Not 

determined 

mg/kgbw/day 160 Acceptable No compound 

related effects 

were 

observed 

Test Type—O: oral; D: dietary; F: flow-through 

Tox Level—mgk: 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/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.

Table 3. Ecotoxicity Data Summary for Formaldehyde 37% 

MRID 

No. 

COMMON 

NAME 

TAXONOMIC 

NAME 

GUIDE 

LINE 

TEST 

TYPE 

% 

AI 

STUDY 

TIME 

DOSE 

TYPE 

TOXI 

CITY 

TOX 

LEVEL NOEL STUDY STATUS 

TOX 

CATEGORY 

Avian Acute Oral Toxicity 

148774 Bobwhite 

quail 

Colinus 

virginianus 

850.2100 

(71-1) 

O 37 21 days LD50 790 mgk 464 Acceptable Slightly 

toxic 

Avian Subacute Dietary Toxicity 

148775 Mallard 

duck 

Anas 

platyrhynchos 

850.2200 

(71-2b) 

D 37 8 days LC50 >5000 ppm 5000 Acceptable Practically 

nontoxic 

148773 Bobwhite 

quail 

Colinus 

virginianus 

850.2200 

(71-2a) 

D 37 8 days LC50 >5000 ppm 5000 Acceptable Practically 

nontoxic 

Freshwater Fish Acute Toxicity 

132485 Rainbow 

trout 

Oncorhynchus 

mykiss 

850.1075 

(72-1) 

S 37 96 hr LC50 118 ppm 17 Acceptable Practically 

nontoxic 

132485 Bluegill 

sunfish 

Lepomis 

macrochirus 

850.1075 

(72-1) 

S 37 96 hr LC50 100 ppm 50 Acceptable Slightly 

nontoxic 
 Page 9 of 14

MRID 

No. 

COMMON 

NAME 

TAXONOMIC 

NAME 

GUIDE 

LINE 

TEST 

TYPE 

% 

AI 

STUDY 

TIME 

DOSE 

TYPE 

TOXI 

CITY 

TOX 

LEVEL NOEL STUDY STATUS 

TOX 

CATEGORY 

Freshwater Invertebrate Acute Toxicity 

148772 Water flea Daphnia 

magna

850.1010 

(72-2) 

S 37 48 hr EC50 14.31 ppm ----- Acceptable Slightly toxic 

Mammalian Acute Oral Toxicity

 *XLQHD

3LJ

------ 81-1 ----- 37.3% 

soln. 

----- LD50 260 mg/kgbw ----- Acceptable moderately 

toxic 

II 

Test Type—O: oral; D: dietary; S: Static 

Tox Level—mgk: 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/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.

Adverse Ecological Incidents 

There are no reported incidents in the Agency's Ecological Incident Information 

System (EIIS) regarding SHMG. The absence of documented incidents does not 

necessarily mean that such incidents did not occur. 

Ecological Effects Risk Assessment 

An ecological risk assessment was not conducted on the SHMG‘s material 

preservative use patterns described in this document. SHMG uses that have potential for 

environmental exposure are material preservatives discharges. The Agency needs to 

conduct environmental fate and ecological risk assessments for material preservatives 

that potentially pass through waste water treatment plants (WWTPs) and may be 

discharged into terrestrial and aquatic environments. For this ecological risk assessment, 

including an endangered species assessment for all uses, the Agency anticipates needing 

the algal toxicity data outlined on page 10 of this document. 

The Agency has not conducted a risk assessment for SHMG that supports a 

complete endangered species effects determination. The ecological risk assessment 

planned during registration review will allow the Agency to determine whether SHMG’s

use has “no effect or “may affect” federally listed threatened or endangered species 

(listed species) or their designed critical habitats. When an assessment concludes that a 

pesticide’s use “may affect” a listed species or its designated critical habitat, the Agency 

will consult with the U.S. Fish and Wildlife Service and/or National Marine Fisheries 

Services (the Services), as appropriate. 
 Page 10 of 14

Environmental Fate and Ecotoxicity Data Gaps and Anticipated Work 

Environmental fate and ecological risk assessments have not been conducted for 

SHMG. The Agency needs to conduct environmental fate and ecological risk 

assessments for material preservatives that potentially pass through waste water treatment 

plants (WWTPs) and may be discharged into terrestrial and aquatic environments. 

Therefore, the Agency anticipates needing the proposed environmental fate and 

ecotoxicity data for SHMG and/or any of its major degradation products that are of 

potential concern for all registered uses of SHMG. The following environmental fate and 

ecotoxicity data are needed to conduct an environmental fate and ecological risk 

assessment: 

The Agency anticipates needing the following data to conduct a complete 

environmental fate assessment for material preservative uses: 

o (GLN 835.2120) Hydrolysis; 

o (GLN 835.2240) Photodegradation in water; 

o (GLN 850.6800) Modified Activated Sludge Respiration Inhibition; and 

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

Test, or (GLN 835.3280) Simulation Tests to Assess the Biodegradability 

of Chemicals Discharged to Wastewater4

. 

The Agency anticipates needing the following algal toxicity data in order to 

conduct a complete ecological risk assessment, including an endangered 

species assessment: 

o (GLN 850.5400) algal toxicity (Tier II) using freshwater green alga, 

Selenastrum capricornutum. 

 

4

 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 11 of 14

Appendix A. Environmental Fate Guideline Study Justifications

Guideline Number: 835.2120 

Study Title: Hydrolysis

Practical Utility of the Data 

1) What is the value of the study? 

Data characterizing the rate of hydrolytic degradation of SHMG and/or the formation and decline of 

degradates is important in determining the persistence and concentrations of SHMG and potential 

degradates over time in various aquatic environments. For outdoor uses, SHMG can reach surface water 

through direct contact or discharge to WWTPs. SHMG may also reach surface water or groundwater 

through run-off or leaching processes. The Agency will evaluate the potential risks of concern. 

2) How would the data be used? 

The data would establish the significance of chemical hydrolysis as a route for degradation and identify, if 

possible, the hydrolytic transformation products formed that may adversely affect non-target organisms and 

may contaminate water and food source of aquatic organisms. The data would also help establish the 

hydrolytic half-life of SHMG and possibly degradates, and assist in developing a degradation pathway.

3) How could the data affect the risk assessment?

The results of hydrolysis data would indicate if SHMG is persistent or if it degrades into other products 

that may adversely affect nontarget organisms and may contaminate their food and water and possibly soil. 

4) What is triggering the need for this data?

Hydrolysis data is needed to conduct the fate assessment to support material preservatives uses for SHMG. 

Guideline Number: 835.2240 

Study Title: Photodegradation in water

Practical Utility of the Data 

1) What is the value of the study? 

Biocides introduced into aqueous systems in the environment can undergo photolytic transformation by 

sunlight. Results from the photolysis study will indicate the stability and persistence of SHMG and 

potential degradates in an aquatic environment when exposed to sunlight. The Agency will evaluate the 

potential risks of concern.

2) How would the data be used?

The data would establish the significance of chemical photolysis as a route for degradation and identify, if 

possible, the photolytic degradation products formed that may adversely affect non-target organisms and 

may contaminate water and food source of aquatic organisms. The data would also help establish the 

photolytic half-life of SHMG and possibly degradates, and assist in developing a degradation pathway.

3) How could the data affect the risk assessment?

The results of photolysis data would indicate if SHMG is persistent or if it degrades into degradation 

products that may adversely affect nontarget organisms and may contaminate their food. The results of the 

photolysis data would expand the understanding of the results of the hydrolysis data since environmental 

aquatic conditions usually involve exposure to sunlight.

4) What is triggering the need for this data?

Aqueous photodegradation data is needed to conduct the fate assessment to support material preservative 

uses for SHMG. 
 Page 12 of 14

Guideline Number: 850.6800; OECD 209

Study Title: Modified 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.

 
 Page 13 of 14

Guideline Numbers: 835.3110, 835.3220, or 835.3280 

Study Titles: Ready Biodegradability, Porous Pot Test, or Simulation Tests to Assess the Biodegradability of 

Chemicals Discharged to Wastewater (also referred to as Biodegradation in Activated Sludge), respectively

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. This 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 three 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. 

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 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.
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Appendix B: Ecological Guideline Study Justifications 

Guideline Number: 850.5400 

Study Title: Algal toxicity (Tier II) using freshwater green alga, Selenastrum capricornutum

Practical Utility of the Data 

1) What is the value of the study? 

As part of an initial risk assessment, one indicator plant species is tested for phytotoxicity. This study 

would allow the Agency to categorize SHMG as toxic or non-toxic to plants. If toxic, additional higher 

tier plant tests would be needed. An endangered species assessment for endangered or threatened plants is 

not possible without this study.

2) How would the data be used?

This study would be used to evaluate the toxicity of SHMG to non-target plants in terrestrial and aquatic 

ecosystems.

3) How could the data affect the risk assessment? 

Adverse effects to non-target plants in terrestrial and aquatic ecosystems may result in mitigation to protect 

species at risk. Mitigation might include reduced label dosages, neutralization of effluents prior to 

discharge into water, restrictions on use in sensitive ecosystems or where endangered species are present, or 

other mitigation measures.

4) What is triggering the need for this data?

Increased concern from state regulators and the public to evaluate impacts on WWTP operations, 

endangered species, and persistence in the environment, since initial registration, have triggered the need 

for this study. Green algae are critical to ecosystem health and productivity. 

Sign-off Date : 08/11/11 

DP Barcode No. : D392286