Docket Number EPA-HQ-OPP-2013-0086 

www.regulations.gov 

Trichloromelamine Preliminary Work Plan 

Registration Review: Initial Docket 

Case Number 3144 

Approved by: 

Date: 

March 2013 

Susan Lewts 

Acting Director 

Antimicrobials Division 

Page 1 of37 
Page 2 of 37

Trichloromelamine Registration Review Team 

Human Health & Environmental Effects

William Hazel 

Tim Dole 

Jenny Tao 

Siroos Mostaghimi 

Srinivas Gowda 

James Breithaupt 

David Bays 

Risk Management

Seiichi Murasaki 

Lance Wormell 

Office of General Counsel

Philip Ross 

 
Page 3 of 37

Table of Contents 

1 Introduction ............................................................................................................................. 5

1.1 Statutory and Regulatory Authority ................................................................................. 5

1.2 Case Overview ................................................................................................................. 7

1.3 Chemical Identification and Properties ............................................................................ 7

1.4 Use/Usage Description ..................................................................................................... 8

1.4.1 Registrations ............................................................................................................. 8

1.4.2 Summary of Registered Uses .................................................................................... 8

1.4.3 Usage Information .................................................................................................... 8

1.5 Regulatory History ........................................................................................................... 8

1.5.1 Recent/Pending Regulatory Actions ......................................................................... 8

1.5.2 Tolerance Information .............................................................................................. 9

1.6 Incidents ........................................................................................................................... 9

1.6.1 Human Health ........................................................................................................... 9

1.6.2 Ecological ................................................................................................................. 9

2 Anticipated Data Needs .......................................................................................................... 9

3 Human Health Risk Assessment ........................................................................................... 11

3.1 Existing Toxicological Endpoints .................................................................................. 11

3.2 Dietary Exposure ............................................................................................................ 12

3.2.1 Food ........................................................................................................................ 12

3.2.2 Drinking Water ....................................................................................................... 12

3.3 Occupational and Residential Exposures ....................................................................... 12

3.3.1 Occupational Handler Exposure ............................................................................. 12

3.3.2 Residential Exposures ............................................................................................. 14

3.4 Aggregate and Cumulative Exposure ............................................................................. 14

3.4.1 Aggregate Exposures .............................................................................................. 14

3.4.2 Cumulative Exposures ............................................................................................ 14

4 Environmental Risk Assessment........................................................................................... 14

4.1 Environmental Conceptual Model Exposure Pathways ................................................. 15

4.2 Ecological Effects Assessment ....................................................................................... 16

4.2.1 Mechanism of Action .............................................................................................. 16

4.2.2 Measures of Effect (Ecotoxicology Endpoints) ...................................................... 16

4.3 Exposure and Effects Analysis Plan ............................................................................... 17

5 Endocrine Disruptor Screening Program (EDSP) ................................................................. 17

6 Guidance for Commenters .................................................................................................... 18

6.1 Preliminary Work Plan ................................................................................................... 18

6.1.1 Trade Irritants .......................................................................................................... 18

6.1.2 Water Quality .......................................................................................................... 18

6.1.3 Environmental Justice ............................................................................................. 18

6.1.4 Structure Activity Relationships ............................................................................. 19

6.1.5 Additional Information ........................................................................................... 20

7 Next Steps ............................................................................................................................. 20

8 References ............................................................................................................................. 21

Appendix A Toxicology Profile ............................................................................................... 23

Appendix B Environmental Fate ............................................................................................. 29
Page 4 of 37

List of Tables 

Table 1 – Summary of Anticipated Risk Assessments and Data Needs: TCM .............................. 6

Table 2 – Anticipated Registration Review Schedule .................................................................... 6

Table 3 – Chemical Identification of TCM ..................................................................................... 7

Table 4 – Physical-Chemical Properties for TCM .......................................................................... 7

Table 5 – Summary of TCM Registered Uses ................................................................................ 8

Table 6 – Studies Anticipated to be Needed for the Registration Review of TCM ...................... 10

Table 7 – Toxicological Endpoints from the 2005 RED .............................................................. 11

Table 8 – TCM Occupational MOEs included in the RED .......................................................... 13

Table 9 – Occupational Handler Exposure Scenarios for TCM ................................................... 13

Table 10 – Residential Exposure Scenarios for TCM .................................................................. 14

Table 11 – Existing Effects Endpoints for Risk Assessment of TCM .......................................... 16

Table 12 – Acute Toxicity Studies for TCM ................................................................................ 23

Table 13 – Summary of Subchronic and Developmental Toxicity and Mutagenicity Data for 

TCM .............................................................................................................................................. 24

Table 14 – Environmental Fate Data for TCM and Related Compounds Containing a Symmetric 

Triazine Ring ................................................................................................................................ 32

Table 15 – Changes in Protolysis (Hydrolysis) of Solutions Containing Hypochlorite Ion. ........ 36

List of Figures 

Figure 1 – Conceptual Model for Ecological Exposure and Effects of Melamine, Primary 

Degradate of TCM, and Its Major Reaction Products/Degradates to Aquatic and Terrestrial 

Organisms ..................................................................................................................................... 15

Figure 2 – Formation and Decline of Cyanuric Acid from Compounds with a Symmetric Triazine 

Ring. .............................................................................................................................................. 30

 
Page 5 of 37

1 Introduction 

This document is the Environmental Protection Agency’s (EPA or “the agency”) Preliminary 

Work Plan (PWP) for trichloromelamine (TCM). The PWP document explains what EPA's 

Office of Pesticide Programs knows about TCM, highlighting anticipated data and assessment 

needs, identifying the types of information that would be especially useful to the agency in 

conducting the review, and providing an anticipated timeline for completing TCM’s review. 

The registration review process was designed to include a public participation component to 

solicit input from interested stakeholders. The agency intends, by sharing this information in the 

docket, to inform the public of what it knows about TCM and what types of new data or other 

information would be helpful for the agency to receive as it moves toward a decision on TCM. 

The agency encourages all interested stakeholders to review the PWP and to provide comments 

and additional information that will help the agency’s decision-making process for this chemical. 

1.1 Statutory and Regulatory Authority 

The Food Quality Protection Act (FQPA) of 1996 mandated a registration review program. All 

pesticides distributed or sold in the United States generally must be registered by EPA based on 

scientific data showing that they will not cause unreasonable risks to human health or the 

environment when used as directed on product labeling. The registration review program is 

intended to make sure that, as the ability to assess risk evolves and as policies and practices 

change, all registered pesticides continue to meet the statutory standard of no unreasonable 

adverse effects to human health or the environment. Changes in science, public policy, and 

pesticide use practices will occur over time. Through the registration review program, the agency 

periodically reevaluates pesticides to make sure that as change occurs, products in the 

marketplace can be used safely. Information on this program is provided at 

http://www.epa.gov/oppsrrd1/registration_review/. 

The agency is implementing the registration review program pursuant to Section 3(g) of the 

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and will review each registered 

pesticide every 15 years to determine whether it continues to meet the FIFRA standard for 

registration. The regulations governing registration review begin at 40 CFR 155.40. The agency 

will consider benefits information and data as required by FIFRA. The public phase of 

registration review begins when the initial docket is opened for each case. The docket is the 

agency’s opportunity to state what it knows about the pesticide and what additional risk analyses 

and data or information it believes are needed to make a registration review decision. After 

reviewing and responding to comments and data received in the docket during this initial 

comment period, the agency will develop and commit to a Final Work Plan (FWP) and 

anticipated schedule for the Trichloromelamine Case. 

Documents associated with this registration review can be viewed at http://www.regulations.gov 

in docket EPA-HQ-OPP-2013-0086. Below is a summary of the issues relevant to this 

registration review case. 
Page 6 of 37

Table 1 – Summary of Anticipated Risk Assessments and Data Needs: TCM 

Risk Assessment 

Assessment 

Necessary to 

Support 

Registration 

Review 

Date of 

Most 

Recent 

Assessment 

Type of 

Assessment 

Required 

(New/Updated) 

Data Anticipated as Needed 

(See Table 6 for details) 

Dietary (food) Yes 5/26/2005 Updated Food Contact Surface Residue 

in vivo Mutagenicity Data 

Dietary (drinking water) No (see 3.2.2) N/A N/A None 

Occupational Handler Yes 9/15/2005 Updated Indoor Exposure Data 

in vivo Mutagenicity Data 

Residential Handler Yes N/A New Indoor Exposure Data 

in vivo Mutagenicity Data 

Residental Post 

Application - Incidental 

Oral and Dermal 

Yes N/A New Surface Residue Data 

in vivo Mutagenicity Data 

Aggregate Yes N/A New 

Indoor Exposure Data 

Food Contact Surface Residue 

Surface Residue Data 

in vivo Mutagenicity Data 

Cumulative No (see 3.4.2) N/A N/A None 

Tolerance Review Yes N/A New None 

Ecological No (see 4.2) N/A N/A None 

N/A = Not applicable 

Table 2 – Anticipated Registration Review Schedule 

Anticipated Activity Target 

Date* Completion Date

Phase 1: Opening the Docket 

Open Docket and 60-Day Comment Period for Preliminary Work Plan 2013-03 2013-03-27 

Close Public Comment Period 2013-05 

Phase 2: Case Development 

Issue Final Work Plan 2013-09 

Issue Data Call-In (DCI) 2014-09 

Receive Data to be Considered in Risk Assessment 2016-09 

Open 30-Day Public Comment Period for Preliminary Risk Assessment(s) 2019-03 

Close Public Comment Period 2019-04 

Phase 3: Registration Review Decision and Implementation 

Open 60-Day Public Comment Period for Proposed Decision 2019-09 

Close Public Comment Period 2019-11 

Issue Final Decision 2020-03 

Begin Post-Decision Follow-up 2020 

Total (years) 7 

*The anticipated schedule will be revised as necessary (e.g., need arising under the Endocrine Disruptor Screening Program with

respect to the active ingredients in this case). 
Page 7 of 37

1.2 Case Overview 

The docket for the Trichloromelamine Case (Case 3144) has been established at 

http://www.regulations.gov in docket number EPA-HQ-OPP-2013-0086. 

1.3 Chemical Identification and Properties 

Table 3 presents the active ingredient to be assessed in Case 3144: Trichloromelamine (TCM) 

(PC Code 077101). 

Table 3 – Chemical Identification of TCM1

Chemical Name Trichloromelamine (TCM) 

Classification Triazine; Amine; Organochlorine

PC Code 077101 

CAS No. 7673-09-8 

Molecular Formula C3H3Cl3N6

Molecular Weight 229.46 g/mol 

% Available chlorine 91.5% 

Molecular Structure 

The TCM product chemistry information relevant to risk assessment is summarized in Table 4. 

Table 4 – Physical-Chemical Properties for TCM1

OPPTS 

Guideline No. Physical and Chemical Properties TCM 

830.1550 Product identity and composition Refer to Table 3. 

830.1650 Description of Formulation Process Confidential Business Information (CBI) 

830.6302 Color Cream or white powder 

830.6303 Physical State Solid 

830.6304 Odor Chlorine- or bleach-like odor 

830.6313 Stability to sunlight, normal and 

elevated temperature, metals/metal ions Stable under normal conditions. 

830.7000 pH 4.7 (5% w/w slurry in water) 

830.7050 UV/Visible Absorption The chemical structure suggests that it will not absorb in 

the UV spectral region (stable to sunlight for 40 minutes). 

830.7200 Melting point >300 °C 

830.7220 Boiling point Not applicable (substance is solid). 

830.7300 Density 0.34 g/cm3 at 20oC 

830.7370 Dissociation Constant Not applicable 

830.7550 Partition coefficient (n-octanol/water) 1.43 

830.7840 Solubility in water 0.064 g/100 mL (20 °C). Soluble in aqueous caustic 

solution, glacial acetic acid and acetone. 

830.7950 Vapor pressure 7.08 x 10-5 mmHg 

 

1

 Source: MRIDs 42131001, 42131101, 42283401, 42385101, 43350301, 43350302, 43350303, and 43395401, 

Trichloromelamine RED (2005) and EPI Suite v4.1 
Page 8 of 37

1.4 Use/Usage Description 

1.4.1 Registrations 

There are six EPA-registered products that contain TCM as an active ingredient (a.i.). The 

products include two technical or manufacturing use products and four end-use products 

formulated as powders and packaged in canisters or small packets. 

1.4.2 Summary of Registered Uses 

Table 5 presents a summary of the registered uses of TCM that will be assessed in this 

registration review. TCM can be applied by the following application methods: mop, sponge, 

cloth, spray, and immersion. 

Table 5 – Summary of TCM Registered Uses 

Use Application 

Method

Application Rate 

(In Terms of 

Available Chlorine)

Food service areas (e.g., restaurants, schools, nursing homes, hospitals, food processing plants, hotels, day 

care centers, and homes)

Dishware, Utensils, Glassware Immersion2 100 to 200 ppm 

Nonporous hard surfaces such as table tops, countertops, sinks, splash 

backs, trays, sealed floors and food processing / preparation equipment.

Mop, sponge, cloth 

or spray 

100 to 200 ppm 

Soft serve, yogurt, shake, slush and food equipment Immersion3 100 to 200 ppm 

1.4.3 Usage Information 

There is no mention of TCM in the Kline Biocides Report for 2004/2005 (Kline, 2005), however, 

production volume data in the EPA Section Seven Tracking System (SSTS) for the years 2008 

through 2010 indicate that no more than 50,000 pounds of TCM were sold per year in the United 

States4. 

1.5 Regulatory History 

The first product containing TCM as an active ingredient was registered in the United States in 

1959. The Agency completed a Reregistration Eligibility Decision (RED) for TCM in 2005. 

1.5.1 Recent/Pending Regulatory Actions 

The post-RED Data Call-In (DCI) was issued in 2008. A follow-up DCI requiring skin 

sensitization data was issued in 2010. 

 

2

 Applied in last sink prior to air drying 

3

 Air dried 

4

 Data for the years 2011and 2012 were not used in this estimate since data collection is still in progress. 
Page 9 of 37

1.5.2 Tolerance Information 

A tolerance exemption has been established for TCM used as a sanitizer on food processing 

equipment and utensils [40 CFR 180.940(c)]5

. TCM must be used such that the end-use 

concentration of all di- or trichloroisocyanuric acid chemicals in the solution is not to exceed 200 

ppm determined as total available chlorine. The wording of this exemption will be revisited 

during the risk assessment stage of this registration review. In addition, although uses in public 

eating places have been approved, a tolerance exemption for TCM used as a sanitizer in public 

eating places has not been established at 40 CFR 180.940(a). The Agency will assess the need 

for a tolerance during this registration review. The U.S. FDA has cleared TCM sanitizing 

solution to be used on food-processing equipment and utensils and other food-contact articles 

except milk containers or equipment at 100-200 ppm [(21 CFR 178.1010(b)(10)]. TCM has also 

been cleared by FDA for use in adhesives for food-packaging material (21 CFR §175.105) 

although no products are currently registered for that use. 

1.6 Incidents 

1.6.1 Human Health 

A total of 48 human health incidents are listed in the OPP Incident Data System (IDS) for TCM 

for the time period spanning 2005 to 2012. Ten of these incidents are rated as moderate (Code 

HC) and 38 are rated as minor (Code HD). 

Five of the moderate incidents involved skin effects including: rash, blistering, peeling skin, 

open sores, and in one case, a second-degree chemical burn. The skin incidents occurred after 

exposure to the diluted product as it was being used to treat glassware. In most cases, gloves 

were not worn. Three incidents occurred when dust from the undiluted product got into the eye 

causing irritation, and in one case, a corneal burn which required antibiotic treatment. One 

incident occurred when a worker accidentally inhaled some undiluted product and experienced 

shortness of breath. Another incident occurred when a restaurant patron experienced severe 

throat irritation and vocal cord effects after drinking water allegedly contaminated with the 

product. 

Symptoms reported for the 38 minor incidents included dermal, ocular, respiratory, and 

gastrointestinal irritation as well as vomiting. Because the incidents were classified as minor, the 

causes of exposure were not included in the incident reports. 

1.6.2 Ecological 

No TCM ecological incidents have been reported in the Agency’s Ecological Incident 

Information System (EISS) for the time period spanning 2005 to 2012. 

2 Anticipated Data Needs 

Table 6 presents a summary of the data anticipated as being needed to support this registration 

review. 

 

5

 Expressed as 1,3,5-Triazine, N,N′,N′′-trichloro-2,4,6-triamino-. 
Docket Number EPA-HQ-OPP-2013-0086 

www.regulations.gov 

Page 10 of 37

Table 6 – Studies Anticipated to be Needed for the Registration Review of TCM GLN Study Name Test Substance

Time Frame (Measured in months from DCI Receipt)

Risk Assessment(s) Data Will Support

Use Site(s) Triggering Anticipated Data Requirement

Applicable 

Studies Anticipated to be Required through the Registration Review DCI 870.5385 or 870.5395 

In Vivo Mammalian Bone Marrow Chromosomal Aberration Test or In Vivo Mammalian Erythrocyte Micronucleus Test 

TGAI 12 All 

All (see Mutagenicity discussion in Appendix A for details) 

All scenario

875.1700 Product Use Information TGAI 12 All All All scenario875.23006 Indoor Surface Residue Dissipation TGAI 24 Residential Surface disinfection of household floors 

Dermal and to TCM andexpected foon floors diproducts. 

Special Study 

Residue Migration Studies From Food Contact Surfaces TEP 24 Dietary Food Contact Surfaces Dietary exp

contact surf

Studies Required through the Post-RED DCI (GDCI-077101-27850) Issued October 8, 2008 875.12007 Indoor Exposure, Dermal 

TGAI 12 Occupational and Residential Hard Surface Disinfection 

1. Mix “last 2. Soak foo3. Mop App4: Trigger SApplication 

875.14007 Indoor Exposure, Inhalation 875.28007 Description of Human Activities Studies No Longer Required through the Post-RED DCI 870.34658 90-day inhalation toxicity study TGAI 24 Occupational and Residential Hard Surface Disinfection Military me6 In the absence of surface residue data, the standard assumption of 100 percent transferable surface residue will be used. 7 It may be possible to use proprietary surrogate exposure data if data compensation issues are appropriately and adequately addressed. 8 The agency has determined that this study can be waived since the only product registered for use on mess kits was voluntarily cancelle
Docket Number EPA-HQ-OPP- 2013-0086 

www.regulations.gov 

Page 11 of 37

3 Human Health Risk Assessment 

The agency anticipates the need to conduct a human health risk assessment for TCM. The agency 

expects to require additional data for use in conducting the registration review. 

3.1 Existing Toxicological Endpoints 

EPA anticipates the need to revise the existing toxicological endpoints as part of this registration 

review. Table 7 presents the endpoints used in EPA’s most recent human health risk assessment 

in support of the 2005 RED. Available information including existing toxicology studies, valid 

scientific literature, and the studies that are expected to be required for registration review will be 

considered in establishing the endpoints to be used in the registration review risk assessment. A 

detailed description of the toxicity studies is provided in Appendix A . 

Table 7 – Toxicological Endpoints from the 2005 RED 

Exposure Scenario Dose Used in Risk 

Assessment (mg/kg/day)

Target Margin of Exposure 

(MOE), Uncertainty Factor (UF), 

FQPA Safety Factor (SF)9

Study and Toxicological 

Effects (See Appendix A for 

details)

Acute Dietary (General 

Population including infants 

and children) 

Acute Reference Dose 

(RfD) = 0.3 mg/kg/day 

UF = 100 

FQPA SF = 1 

acute Population Adjusted Dose 

(aPAD) = acute RfD

FQPA SF= 0.3 mg/kg/day 

90-Day Oral Rodent Study 

(MRID 43064301) 

Lowest Observed Adverse 

Effect Level (LOAEL) = 150 

mg/kg/day 

No Observed Adverse Effect 

Level (NOAEL) = 30 

mg/kg/day 

Chronic Dietary (All 

populations) 

Chronic RfD = 0.1 

mg/kg/day 

UF = 30010

FQPA SF = 1 

chronic Population Adjusted Dose 

(cPAD) = chronic RfD

FQPA SF= 0.1 mg/kg/day 

90-Day Oral Rodent Study 

(MRID 43064301) 

LOAEL = 150 mg/kg/day 

NOAEL = 30 mg/kg/day 

Short-Term Incidental Oral 

(1-30 days) 

Oral Study Target MOE = 100 

UF = 100 

See study for Acute/Chronic 

Dietary Endpoint 

Intermediate-Term 

Incidental Oral (1- 6 

months) 

Oral Study Target MOE = 100 

UF = 100 

See study for Acute/Chronic 

Dietary Endpoint 

Short/Intermediate-Term 

Dermal Exposure 

Oral Study / Dermal 

Absorption=100% 

Target MOE =100 

UF = 100 

See study for Acute/Chronic 

Dietary Endpoint 

Short/Intermediate-Term 

Inhalation Exposure 

No appropriate route-specific study was available. The oral endpoint of 30 mg/kg with a 

MOE of 100 (10x interspecies extrapolation, 10x intraspecies variation) is used. An 

additional 10x route-to-route extrapolation is used to determine if a confirmatory inhalation 

toxicity study is warranted. 

 

9

 Developmental toxicity studies showed a lack of effects in offspring up to and including the highest doses tested, 

and the LOAELs were based on general systemic effects that were not considered severe. Studies were welldesigned and provided an adequate dose-response for TCM. Therefore, the FQPA Safety Factor was removed. 

10 UF of 300 includes a 10x interspecies extrapolation, 10x intraspecies variation, and 3x extrapolation from a 

subchronic study to a chronic duration. 
Page 12 of 37

3.2 Dietary Exposure 

3.2.1 Food 

In the 2005 RED, acute and chronic dietary risks to military personnel using treated mess kits 

and consuming treated fruits and vegetables were ≤7.1% and ≤21% of the aPAD and cPAD, 

respectively. Because the only product registered for use on mess kits and for fruit and vegetable 

washes was voluntarily cancelled effective July 19, 2009, these risks do not need to be 

reassessed. Acute dietary risks to civilians eating in public eating places were ≤32% of the aPAD 

and chronic dietary risks were ≤54% of the cPAD with children being the most exposed 

population subgroup. 

EPA anticipates the need to revise the acute and chronic dietary (food) risk assessment 

conducted in support of the 2005 RED. TCM is expected to be rapidly hydrolyzed to melamine 

and hypochlorous acid. The melamine is further degraded to ammeline and ammelide before 

degrading to cyanurate/isocyanurate. Residue chemistry data are expected to be needed to 

determine dietary exposure to the moderately stable degradates melamine and 

cyanurate/isocyanurate following sanitization of food contact surfaces of food processing plants 

and food-handling facilities (including public eating places). Acute and chronic dietary risk 

assessments are anticipated to be needed to estimate dietary exposure of all population subgroups 

to melamine and cyanurate/isocyanurate. 

3.2.2 Drinking Water 

EPA does not anticipate the need to conduct a drinking water assessment since dietary exposure 

from drinking water is not expected to occur. TCM is registered only for indoor use as a food or 

nonfood contact surface sanitizer. There are no approved uses expected to result in direct aquatic 

exposure or discharges of TCM and its degradates into a water system. As a result, the agency 

maintains its determination in the RED that a drinking water assessment is not necessary for 

TCM. No residue chemistry data are expected to be needed to characterize drinking water 

exposures. 

3.3 Occupational and Residential Exposures 

The agency anticipates the need to revise the occupational and residential assessments conducted 

in support of the 2005 RED since Margins of Exposure (MOE) were calculated using exposure 

data sets in which the agency has limited confidence; these MOEs will need to be reassessed 

using updated values. Uses of TCM that may result in occupational handler and residential 

handler/postapplication exposure are presented in Table 9 and Table 10. 

3.3.1 Occupational Handler Exposure 

EPA anticipates the need to revise the occupational handler assessment conducted in support of 

the 2005 RED. Occupational handler dermal and inhalation exposures to TCM were assessed in 

the RED for the Army uses involving the dip treatment of mess kits, fruit and vegetables, and for 

food handling establishment uses involving the treatment of utensils and wiping of countertops. 
Page 13 of 37

The specific scenarios included opening and pouring packets into treatment solutions; dipping 

mess kits, utensils, and fruit/vegetables into treatment solutions; and wiping countertops with 

treatment solutions. The inhalation exposures were calculated using unit exposure data from the 

Chemical Manufacturers Association (CMA) antimicrobial exposure study and the Pesticide 

Handlers Exposure Database (PHED). Dermal exposures for the opening/pouring and wiping 

scenarios were calculated using unit exposure data and dermal exposures for the dip treatment 

scenarios were calculated using the film thickness approach. Both the inhalation and dermal 

MOEs were calculated using the NOAEL of 30 mg/kg/day from the 90-day oral rodent study that 

had been selected at the time of the RED (MRID 43064301). 

A summary of the MOEs from the 2005 RED is included in Table 8. All of the MOEs exceeded 

the target MOE of 100 which meant that the risks were not of concern. 

Table 8 – TCM Occupational MOEs included in the RED 

Exposure Scenario Daily Amount 

Used (lb ai) 

Dermal Dose 

(mg/kg/day) 

Dermal 

MOE 

Inhalation Dose 

(mg/kg/day) 

Inhalation 

MOE 

Mess Kit and Fruit and Vegetable Treatments

Open and Pour Packets 0.11511 0.125 240 0.0000677 440,000 

Dip Treat Mess Kits 0.0058 5200 0.0455 660 

Dip Treat Fruits and Vegetables 0.0072 2200 0.0455 660 

Restaurant and Bar Treatments

Open and Pour Packets 0.0029212 0.0032 1,7x107 0.0000017 9,400 

Wipe Countertops 0.12 250 0.00116 26,000 

Dip Treat Utensils 0.00488 6100 0.0016 26,000 

Because the only product registered for use on mess kits and for fruit and vegetable washes was 

voluntarily cancelled effective July 19, 2009, these scenarios will not need to be reassessed 

during registration review. However, all of the other handler scenarios assessed in the RED will 

need to be revised during registration review upon receipt of the unit exposure data that are 

anticipated to be required to supplement or replace the unit exposure data that were used in the 

RED. In addition, a new scenario for spray application is expected to be assessed to account for 

products that were registered after the RED. Occupational handler scenarios to be assessed are 

presented in Table 9. 

Table 9 – Occupational Handler Exposure Scenarios for TCM 

Occupational Exposure Scenario Exposure 

Route(s) Duration 

Mix “last sink” solutions for food service utensils Dermal & 

Inhalation 

Short- and 

Intermediate-term 

Soak food service utensils in TCM “last sink” solutions Dermal & 

Inhalation 

Short- and 

Intermediate-term 

Mop and wipe TCM disinfectant solutions onto hard surfaces in food 

service areas and food processing plants 

Dermal & 

Inhalation 

Short- and 

Intermediate-term 

Trigger spray apply TCM solutions to hard surfaces in food service areas 

and food processing plants 

Dermal & 

Inhalation 

Short- and 

Intermediate-term 

 

11 Two packets each containing 4.77 oz of product containing 19.3% a.i. 

12 One packet containing 0.25 oz of product containing 18.7% a.i. 
Page 14 of 37

3.3.2 Residential Exposures 

EPA anticipates the need to conduct a residential handler assessment. The risk assessment for the 

RED indicated that a separate risk assessment for residential uses had not previously been 

performed because the assessment for occupational handlers in restaurants was considered to be 

a conservative and protective surrogate for residential uses. In addition, the products appeared to 

be intended primarily for food service and preparation areas in commercial and institutional 

facilities. EPA Reg. No. 65169-1, however, includes day care centers and homes as use sites and, 

therefore, it will be necessary to assess postapplication dermal and incidental oral exposure of 

toddlers playing on floors treated with this product. This scenario is included in Table 10. 

Table 10 – Residential Exposure Scenarios for TCM 

Residential Exposure Scenario Exposure Route(s) Duration 

Toddlers playing on floor treated with TCM products Dermal & Incidental Oral Short- and Intermediate-term

3.4 Aggregate and Cumulative Exposure 

3.4.1 Aggregate Exposures 

EPA anticipates the need to conduct an aggregate exposures assessment. Upon a reevaluation 

and selection of toxicological endpoints, combined with the human health exposure assessments 

expected to be needed as a part of this registration review case, aggregate exposures including 

dietary (food) exposures and residential exposures, will need to be assessed. 

3.4.2 Cumulative Exposures 

With respect to cumulative exposure, unlike other pesticides for which EPA has followed a 

cumulative risk approach based on a common mechanism of toxicity, EPA has not made a 

common mechanism of toxicity finding as to TCM and any other substances and TCM does not 

appear to produce a toxic metabolite produced by other substances. For the purposes of this 

registration review, therefore, EPA has not assumed that TCM has a common mechanism of 

toxicity with other substances. For information regarding EPA’s efforts to determine which 

chemicals have a common mechanism of toxicity and to evaluate the cumulative effects of such 

chemicals, see http://www.epa.gov/pesticides/cumulative/. 

4 Environmental Risk Assessment 

The agency does not anticipate the need to conduct a quantitative ecological risk assessment for 

TCM or its degradates. The registered use pattern as a food and non-food contact sanitizer is 

expected to result in minor or insignificant amounts reaching surface waters because of the rapid 

dechlorination to the degradates melamine, hypochlorous acid, and cyanuric/isocyanuric acid 

(see Appendix B ). 

Based on the low hazard and exposure, the agency intends to conclude that the registered uses of 

TCM will have 'no effect' (NE) on endangered or threatened terrestrial or aquatic species, or their 

designated critical habitats, as listed by the U.S. Fish and Wildlife Service (USFWS) and the 
Page 15 of 37

National Oceanic and Atmospheric Administration's (NOAA) National Marine Fisheries Service 

(NMFS). EPA anticipates conducting no further analysis of potential risks to endangered or 

threatened species unless public comment or other submissions provide data or information that 

would otherwise inform the agency's determination. 

4.1 Environmental Conceptual Model Exposure Pathways 

Based on the chemical/physical properties summarized in Table 4, environmental fate 

information (Appendix B ), and the registered use as a food surface sanitizer in Table 5, the 

agency has developed a conceptual model for the environmental exposure to TCM and its 

metabolites/degradates. For the registered use as a food and non-food contact sanitizer, the 

agency assumes that environmental exposures will be minimal. Bioconcentration of any residues 

that reach surface water will not be significant because of their low log Kow (log P) and high 

water solubility values. Any environmental exposure is expected to be of short duration in the 

presence of acclimated microorganisms or anaerobic conditions (Zeyer et al., 1980, Ernst and 

Rehm, 1990, Jessee et al., 1983, Cook et al., 1985, Saldick et al., 1974). Figure 1 illustrates the 

conceptual model for the use of TCM products including as a hard-surface, food contact sanitizer 

which can go down the drain after use. Table 14 in Appendix B contains the details of 

environmental fate studies reviewed. 

Figure 1 – Conceptual Model for Ecological Exposure and Effects of Melamine, Primary Degradate of TCM, 

and Its Major Reaction Products/Degradates to Aquatic and Terrestrial Organisms
Page 16 of 37

4.2 Ecological Effects Assessment 

Ecological effects data are used as measures of direct and indirect effects to biological receptors. 

Acute and chronic toxicity data from studies submitted by pesticide registrants along with the 

available open literature are used to evaluate the potential direct and indirect effects of TCM and 

its degradates on aquatic and terrestrial receptors. 

4.2.1 Mechanism of Action 

TCM is used as a water solution which forms melamine and hypochlorous acid (HClO), an 

oxidizing agent and the biocidal agent. HClO is a weak acid and, depending upon pH, can further 

disassociate into a hydrogen ion and a hypochlorite ion (ClO-), in a reversible reaction. The 

antimicrobial activity of chlorine compounds depends primarily on HClO which can rapidly 

cross cell membranes. While ClO- has some disinfection potential it requires longer contact time. 

It is HClO and ClO- that are the active disinfecting moieties of TCM (see Hypochlorous Acid 

section in Appendix B ). 

4.2.2 Measures of Effect (Ecotoxicology Endpoints)

Current selected ecotoxicological endpoints are summarized in Table 11. The results of the 

submitted studies indicate that TCM is practically nontoxic to Bobwhite Quail on an acute oral 

basis. It is slightly toxic to Bobwhite quail and practically nontoxic to Mallard duck on a dietary 

basis. It is moderately toxic to Bluegill sunfish and Rainbow trout. It is highly toxic to Daphnia. 

An agency memorandum (EPA, 1983), indicates that there is some evidence that melamine, a 

degradate of TCM, may be chronically toxic to fish and invertebrates by causing adverse effects 

on reproduction and embryonic development based on an FDA review of acute toxicity studies 

for melamine. The memorandum noted the FDA conclusion that, although there is insufficient 

evidence to determine the potential environmental toxicity of melamine, there is some basis for 

concern based on the structure-activity-relationship (SAR) of melamine to metaphenylenediamine, and the readily available studies on melamine’s reproductive effects on 

embryonic development of fish and invertebrates. Based on SARs of melamine to metaphenylenediamine, the 96-hour EC50 for melamine for green algae is expected to be 2.4 mg/L 

(moderately toxic). The LC50 for daphnids is expected to be 5.9 mg/L (moderately toxic), and the 

MATC is expected to range between 0.05 and 0.09 mg/L. 

Due to the limited use pattern of this chemical, TCM and its degradates are not expected to enter 

the environment and come into contact with non-target terrestrial and aquatic organisms. 

Therefore, based on lack of exposure, risk to terrestrial and aquatic organisms is not expected. 

Table 11 – Existing Effects Endpoints for Risk Assessment of TCM 

Receptor Group Surrogate Species Risk 

Scenario 

Toxicity Endpoint as 

a.e. 

Reference

Birds Bobwhite quail (Colinus virginianus) Acute LD50 > 5,000 mg/kg 

NOEC = 5,000 mg/kg 42250801
Page 17 of 37

Receptor Group Surrogate Species Risk 

Scenario 

Toxicity Endpoint as 

a.e. 

Reference

Bobwhite quail (Colinus virginianus) Acute LD50 > 2,150 mg/kg 42280801

Mallard duck (Anas platyrhynchos) Acute LC50 > 5,000 mg/kg 

NOEC = 2,500 mg/kg 42247401

Freshwater fish 

Bluegill sunfish (Lepomis 

macrochirus) Acute LC50 = 4.5 mg/L 

NOEC = 1.0 mg/L 41934901

Rainbow Trout Acute LC50 = 4.0 mg a.i./L 

NOEC = 0.56 mg a.i./L 42010601

Freshwater 

invertebrates Daphnia Acute EC50 = 0.80 mg ai/L NOEC = 0.32 mg ai/L 42020801

4.3 Exposure and Effects Analysis Plan 

Based on low likelihood of exposure, a quantitative risk assessment is not anticipated to be 

conducted. No additional ecological effects or environmental fate data are expected to be needed. 

5 Endocrine Disruptor Screening Program (EDSP) 

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse 

outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and 

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, 

reproductive, and general or systemic toxicity. These studies include endpoints which may be 

susceptible to endocrine influence, including effects on endocrine target organ histopathology, 

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and 

chronic studies that assess growth, developmental and reproductive effects in different 

taxonomic groups. As part of its 2005 reregistration decision for TCM, EPA reviewed these data 

and selected the most sensitive endpoints for relevant risk assessment scenarios from the existing 

hazard database. However, as required by FFDCA section 408(p), TCM is subject to the 

endocrine screening part of the Endocrine Disruptor Screening Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including pesticide 

active and other ingredients) may have an effect in humans or wildlife similar to an effect 

produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator 

may designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal 

systems. Chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

testing is designed to identify any adverse endocrine-related effects caused by the substance, and 

establish a dose-response relationship between the dose and the E, A, or T effect. 

Under FFDCA section 408(p), the agency must screen all pesticide chemicals. Between October 

2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 chemicals, 

which contains 58 pesticide active ingredients and 9 inert ingredients. TCM is not among the 
Page 18 of 37

group of 58 pesticide active ingredients on the initial list to be screened under the EDSP. 

Accordingly, as part of registration review, EPA will issue future EDSP orders/data call-ins, 

requiring the submission of EDSP screening assays for TCM. 

For further information on the status of the EDSP, the policies and procedures, the list of 67 

chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our 

website: http://www.epa.gov/endo/. 

6 Guidance for Commenters 

6.1 Preliminary Work Plan 

The public is invited to comment on EPA’s Preliminary Work Plan and rationale. The agency 

will carefully consider all comments as well as any additional information or data provided in a 

timely manner prior to issuing a final work plan for the Trichloromelamine registration review 

case. 

6.1.1 Trade Irritants 

Through the registration review process, the agency intends to solicit information on trade 

irritants and, to the extent feasible, take steps toward facilitating irritant resolution. The agency 

will work to harmonize tolerances and international maximum residue limits (MRLs) and may 

modify tolerance levels to do so, when possible. Stakeholders are asked to comment on any 

trade irritant issues resulting from lack of MRLs or disparities between U.S. tolerances and 

MRLs in key export markets, providing as much specificity as possible regarding the nature of 

the concern. 

6.1.2 Water Quality 

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

section 303(d) of the Clean Water Act13. In addition, no Total Maximum Daily Loads (TMDL) 

have been developed for TCM14. More information on impaired water bodies and TMDLs can be 

found at EPA’s website15. 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 Process16 in order 

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

6.1.3 Environmental Justice 

EPA seeks to achieve environmental justice, the fair treatment and meaningful involvement of all 

people, regardless of race, color, national origin, or income, in the development, implementation, 

and enforcement of environmental laws, regulations, and policies. To help address potential 

 

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

14http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant

_group_name=PESTICIDES 

15 http://www.epa.gov/owow/tmdl/ 

16 http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm 
Page 19 of 37

environmental justice issues, the agency seeks information on any groups or segments of the 

population who, as a result of their location, cultural practices, or other factors, may have 

atypical, unusually high exposure to TCM compared to the general population. Please comment 

if you are aware of any sub-populations that may have atypical, unusually high exposure 

compared to the general population.

6.1.4 Structure Activity Relationships 

EPA must rely upon information of appropriate quality and reliability for each decision made by 

the agency. In the Office of Pesticide Programs (OPP), the evaluation process for a pesticide 

chemical traditionally begins with the applicant’s submission of a set of studies conducted with 

the specific pesticide chemical of interest. The use of the results of such testing (measured data) 

is a logical, scientifically rigorous process that identifies the physical, chemical, and 

environmental fate properties of the pesticide, as well as the dose and endpoints at which an 

adverse effect can occur in various animal species. 

Today, there is significant interest in alternative techniques, i.e., techniques other than data 

generation that could significantly inform the agency’s decision-making process. Recently, OPP 

has made increasing use of structure activity relationship (SAR) as part of its regulatory 

decision-making process. In the SAR process, a chemical's molecular structure is compared to 

that of other chemicals for which data are available. These structural similarities are then used to 

make predictive judgments about a chemical’s physical, chemical, and biological properties. 

Thus, the chemical’s physical, chemical, and biological properties are a function of (or directly 

related to) the chemical’s molecular structure. Quantitative SAR is referred to as QSAR. To 

develop a QSAR, a selected set of measured data on a single physical, chemical, or biological 

property is used to derive a model (an equation) to predict the value of that property. 

Since SAR assessments and QSAR modeling are another set of tools that are available to agency 

scientists, OPP has begun a process shift that envisions shifting from the current study-by-study 

approach to an approach in which the use of predicted data, generated using validated models, is 

considered along with information from open literature and studies specifically generated under 

Part 161 requirements. All relevant information would be considered as part of a weight-of-theevidence evaluation. 

At this time, EPA believes that for certain endpoints, especially physical/chemical and fate 

properties, that SAR and QSAR might be effectively utilized to fulfill these data requirements 

for many antimicrobial pesticide chemicals. When considering biological properties, at this time, 

EPA believes that SAR and QSAR can be most effectively utilized in the evaluation of 

chemicals that exhibit lower toxicity for human health and/or ecotoxicity parameters. This is 

appropriate because the risk assessment for lower toxicity chemicals can be stream-lined, i.e., a 

screening-level assessment procedure rather than multiple tiers of assessments with progressively 

more data requirements. 

If stakeholders believe that submission of predicted data can fulfill one of the data needs for the 

Trichloromelamine Case, then the agency invites submission of this information. The submitter 

would be expected to supply a rationale describing the utility of the information and provide 

documentation on the scientific validity of the information. The determination that the predicted 
Page 20 of 37

data fulfills the data requirement would be at the sole discretion of the agency. Pre-submission 

consultation with the agency is encouraged. 

6.1.5 Additional Information 

Stakeholders are also specifically asked to provide available information and data that will assist 

the agency in refining its risk assessments, including any species-specific ecological effects 

determinations. The agency is interested in receiving the following information: 

1. Confirmation on the following label information: 

A. Sites of application 

B. Formulations 

C. Application methods and equipment 

D. Maximum application rates 

E. Frequency of application, application intervals and maximum number of 

applications 

F. Geographic limitations on use 

2. Use or potential use distribution 

3. Use history 

4. Usage/use information for non-agricultural uses (e.g., materials preservation) 

5. Typical application interval 

6. State or local use restrictions 

7. Ecological incidents (non-target plant damage and avian, fish, reptilian, amphibian and 

mammalian mortalities) not already reported to the agency 

8. Monitoring data 

7 Next Steps 

After the 60-day comment period closes in May 2013, the agency will review and respond to any 

comments received in a timely manner, and then issue a Final Work Plan for the 

Trichloromelamine Case. 
Page 21 of 37

8 References 

An L, Li Z, and Yang Z, et al. (2011) Cognitive deficits induced by melamine in rats. Toxicol Lett. 2011 Oct 

30;206(3):276-80. Epub 2011 Aug 22. 

Bentivegna, S. (2001) Trichloromelamine: A 3-Month Oral (Capsule) Toxicity Study in Dogs with a One-Month 

Recovery Period: Lab Project Number: 003445:85MA0970: DAAD05-00-P8190. Unpublished study 

prepared by Huntingdon Life Sciences. 523 p. (MRID# 45603301) 

Bowman, J. (1986) Acute Toxicity of Trichloromelamine to Bluegill Sunfish (Lepomis macrochirus): Lab Project 

Number: 34811. Unpublished study prepared by ABC Labs, Inc. 17 p. (MRID# 41934901) 

Bowman, J. (1986) Acute Oral Toxicity Trichloromelamine to Rainbow Trout (Salmo gairdneri): Lab Project 

Number: 34812. Unpublished study prepared by Analytical Bio-chemistry Laboratories, Inc. 17 p. (MRID# 

42010601) 

Brown CA, Jeong KS, Poppenga RH, et al. (2007) Outbreaks of renal failure associated with melamine and cyanuric 

acid in dogs and cats in 2004 and 2007. J Vet Diagn Invest. 2007 Sep;19(5):525-31.

Burgess, D.; Frazier, S.; Schoen, L. (1991) Acute Toxicity Trichloromelamine to Daphnia magna: Lab Project 

Number: 34813. Unpublished study prepared by ABC Laboratories, Inc. 15 p. (MRID# 42020801) 

Cifone, M. (1986) Evaluation of Trichloromelamine in the Rat Hepatocyte scheduled DNA Synthesis Assay: Lab 

Project Number: 20991 Unpublished study prepared by Hazleton Laboratories America, Inc. 25 p. (MRID# 

42021701) 

Dobson, RL, Motlagh, S, and Quijano, M, et al. (2008) Identification and characterization of toxicity of 

contaminants in pet food leading to an outbreak of renal toxicity in cats and dogs. Toxicol Sci. 2008 

Nov;106(1):251-62. Epub 2008 Aug 9. 

Early RJ, Yu H, and Mu XP, et al. (2012) Repeat oral dose toxicity studies of melamine in rats and monkeys. Arch 

Toxicol. 2012 Sep 28. 

Fletcher, D.; Pedersen, C. (1988) Trichloromelamine: 8-Day Acute Dietary LC50 Study in Mallard Ducklings: Lab 

Project Number: 88 DC 109. Unpublished study prepared by Bio-Life Associates, Ltd. 26 p. (MRID# 

42247401) 

Fletcher, D.; Pedersen, C. (1988) Trichloromelamine: 21-Day Acute Dietary LD50 Study in Bobwhite Quail: Lab 

Project Number: BLAL 88 QD 109. Unpublished study prepared by Bio-Life Assocs. 31 p. (MRID# 

42250801) 

Fletcher, D.; Pedersen, C. (1988) Trichloromelamine: 8-Day Acute Dietary LC50 Study in Bobwhite Quail: Lab 

Project Number: BLAL 88 QC 110. Unpublished study prepared by Bio-Life Associates, Ltd. 25 p. 

(MRID# 42280801) 

Gamboa da Costa, G, Jacob, CC, and Von Tungeln, LS, et al. (2012) Dose-response assessment of nephrotoxicity 

from a twenty-eight-day combined-exposure to melamine and cyanuric acid in F344 rats. Toxicol Appl 

Pharmacol. 2012 Jul 15;262(2):99-106. Epub 2012 May 2. 

Glaza, S. (1994) Acute Dermal Toxicity Study in Trichloromelamine (TCM), #14468W46 in Rabbits: Final Report: 

Lab Project Number: HWI 31102386: TP3016. Unpublished study prepared by Hazleton Wisconsin, Inc. 

31 p. (MRID# 43159901) 

Glaza, S. (1994) Primary Eye Irritation Study of Trichloromelamine (TCM), #14468W46 in Rabbits: Final Report: 

Lab Project Number: HWI 31102388: TP3015. Unpublished study prepared by Hazleton Wisconsin, Inc. 

26 p. (MRID# 43159902) 

Glaza, S. (1994) Primary Dermal Irritation Study of Trichloromelamine (TCM), #14468W46 in Rabbits: Final 

Report: Lab Project Number: HWI 31102387: TP3014. Unpublished study prepared by Hazleton 

Wisconsin, Inc. 24 p. (MRID# 43159903) 

Glaza, S. (1994) Dermal Sensitization Study of Trichloromelamine (TCM), #14468W46 in Guinea Pigs--Closed 

Patch Technique: Final Report: Lab Project Number: HWI 31102389: TP2008. Unpublished study prepared 

by Hazleton Wisconsin, Inc. 38 p. (MRID# 43159904) 

Glaza, S. (1994) Acute Oral Toxicity Study of Trichloromelamine (TCM), #14468W46 in Rats: Final Report: Lab 

Project Number: HWI/31102385. Unpublished study prepared by Hazleton Wisconsin, Inc. 44 p. (MRID# 

43165701) 

Ivett, J. (1986) Clastogenic Evaluation of Trichloromelamine in an In Vitro Cytogenic Assay Measuring 

Chromosomal Aberration Freq- uencies in Chinese Hamster Ovary (CHO) Cells: Lab Project Number : 

20990. Unpublished study prepared by Hazelton Laboratories America, Inc. 33 p. (MRID# 42021801) 
Page 22 of 37

Jacob, CC, Reimschuessel, R, and Von Tungeln, LS, et al. (2010) Dose-response assessment of nephrotoxicity from 

a 7-day combined exposure to melamine and cyanuric acid in F344 rats. Toxicol Sci. 2011 Feb;119(2):391-

7. Epub 2010 Oct 28. 

Jacob CC, Von Tungeln LS, and Vanlandingham M, et al. (2012) Pharmacokinetics of melamine and cyanuric acid 

and their combinations in F344 rats. Toxicol Sci. 2012 Apr;126(2):317-24. Epub 2012 Jan 6. 

Jagannath, D. (1987) Evaluation of Trichloromelamine, (...) in Ames Salmonella/ Microsome Reverse Mutation 

Assay: Lab Project Number: 20988. Unpublished study prepared by Hazleton Labs., America, Inc. 26 p. 

(MRID# 42148801) 

Kim SH, Lee IC, and Lim JH, et al. (2011) Effects of melamine on pregnant dams and embryo-fetal development in 

rats. J Appl Toxicol. 2011 Jun 27. doi: 10.1002/jat.1703. 

Michie, M. (1989) Trichloromelamine--90-Day Subchronic Study in Rats: LabProject Number: 75-51-0743-88: 40-

0743-88. Unpublished study prepared by U.S. Army Environmental Hygiene Agency. 1177 p. (MRID# 

43064301) 

OECD SIDS Dossier for Melamine, UNEP Publications, June, 2002. 

http://www.inchem.org/documents/sids/sids/108781.pdf accessed in November, 2012. 

Pang J, Li GQ, and Li CR, et al. (2011) Toxicokinetic study of melamine in the presence and absence of cyanuric 

acid in rats. J Appl Toxicol. 2011 Nov 17. doi: 10.1002/jat.1764. 

Park D, Kim TK, and Choi YJ, et al. (2011) Increased nephrotoxicity after combined administration of melamine 

and cyanuric Acid in rats. Lab Anim Res. 2011 Mar;27(1):25-8. Epub 2011 Mar 26. 

Puschner B, Poppenga RH, Lowenstine LJ, et al. (2007) Assessment of melamine and cyanuric acid toxicity in cats. 

J Vet Diagn Invest. 2007 Nov;19(6):616-24. 

Tyl, R.; Marr, M.; Myers, C. (1995) Developmental Toxicity Evaluation of Trichloromelamine Administered by 

Gavage to New Zealand White Rabbits: Final Report: Lab Project Number: 65C-5742-300/400. 

Unpublished study prepared by Research Triangle Institute. 215 p. (MRID# 43614301) 

Tyl, R.; Marr, M.; Myers, C. (1995) Developmental Toxicity Evaluation of Trichloromelamine Administered by 

Gavage to CD (Sprague-Dawley) Rats: Final Report: Lab Project Number: 65C-5742-100/200. 

Unpublished study prepared by Research Triangle Institute. 246 p. (MRID# 43614302) 

U. S. EPA, 1983. Meeting with FDA Toxicology Department concerning their evaluation of pituitary tumor 

incidence in male Fischer 344 rats and bone marrow leukemia incidence in female F 344 rats in the 30-

month melamine study submitted by American Cyanamin (1983). Memorandum from Stephanie April, 

Toxicology Branch, to Tim Gardner, Registration Division. December 14, 1983. 

U.S. EPA (1984) Memorandum: Melamine Studies. From Stephanie P. April, Toxicology Branch, to James Davis, 

Pesticide and Toxic Substances. May 2, 1984. 

U.S. EPA (1993) Memorandum: Carcinogenicity Peer Review of Melamine. From Stephen C. Dapson, Senior 

Pharmcologist, HED, and Esther Rinde, Manager of Carcinogenicity Peer Review Committee, HED, to 

Phil Hutton, Insecticide-Rodenticide Branch, Registration Division. July 21, 1993. 

U.S. EPA (1994) Memorandum: Review of Acute Toxicity Studies Submitted in Response to DCI. From Jess 

Rowland, Toxicologist, HED to K. Davis and B. Alder, Product Managers, Reregistration Division. July 

21, 1994. 

U. S. EPA, 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs U.S. 

Environmental Protection Agency - Endangered and Threatened Species Effects Determinations, Appendix 

A, Section IIB, pg.81. US Environmental Protection Agency. January 24, 2004. 

http://www.epa.gov/oppfead1/endanger/consultation/ecorisk-overview.pdf. 

U.S. EPA (2005a) Reregistration Eligibility Decision Document (RED) for Trichloromelamine (Case 3144), 

September 2005. http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2005-0262-0002 

U.S. EPA (2005b) Trichloromelamine Risk Assessment for the Reregistration Eligibility Decision. September 15, 

2005. http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2005-0262-0003 

Viau, A. (1994) An Evaluation of the Acute Toxicity of Inhaled Trichloromelamine Dry Powder Formulation in the 

Albino Rat: Lab Project Number: 90906. Unpublished study prepared by Bio- Research Lab., Ltd. 190 p. 

(MRID# 43368501) 
Docket Number EPA-HQ-OPP-2012-0682 

www.regulations.gov 

Page 23 of 37

Appendix A Toxicology Profile 

Acute Toxicity for Product Labeling 

As listed in Table 12, TCM is Toxicity Category I for primary eye irritation, Category II for 

acute oral, inhalation toxicity, and primary skin irritation, and Category III for acute dermal 

toxicity. It is not a skin sensitizer. All acute toxicity data are adequate for currently registered 

uses. The agency does not anticipate that any additional technical acute toxicity information will 

be needed for the registration review of TCM. 

Table 12 – Acute Toxicity Studies for TCM 

Guideline No./ Study Type MRID Results Toxicity 

Category

870.1100 / Acute Oral (93% a.i.) 43165701LD50 = 398 mg/kg II 

870.1200 / Acute Dermal 43159901LD50 > 2000 mg/kg III 

870.1300 / Acute Inhalation (100% 

a.i.) 43368501LC50 = 0.4 mg/L, males and 0.780 mg/L, females II 

870.2400 / Primary Eye Irritation 

(95% a.i.) 43159902 Severe conjunctival irritation I 

870.2500 / Primary Dermal Irritation 

(95.1% a.i.) 43159903 Severe irritant II 

870.2600 / Dermal Sensitization 

(95.1% a.i.) 43159904 No sensitization reactions for group treated with 0.1% [w/v] solution N/A 

N/A=Not available 

Subchronic Toxicity 

TCM caused mortality in mid- and high-dose groups in a 90-day oral toxicity study in rats 

(MRID 43064301). Gross necropsy revealed hemorrhagic erosions of the stomach mucosa as 

well as stomach and intestinal distention, and congestion of the lung with white spotting at 

varying degrees. Significantly (p<0.05) lower body weight gain was seen in the high-dose group. 

Histopathology examination revealed engorgement of the small blood vessels of the adrenal 

gland, brain, kidneys, liver, lung, and pituitary gland as well as pulmonary edema. TCM also 

induced mild to moderate chronic inflammation and moderate hyperplasia of the non-glandular 

stomach at the high-dose level as well as a moderate hyperplasia in one mid-dose male. A 

NOAEL of 30 mg/kg/day (low-dose) and a LOAEL of 150 mg/kg/day (mid-dose) were 

established, based on histopathological lesions. 

Developmental Toxicity 

TCM did not show developmental effects in a rat developmental study (MRID 43614302). 

Clinical signs, including alopecia, gasping, altered respiration, salivation, lethargy, and 

chromodacryorrhea were observed at one or more dose levels. Reduction in body weight gains 

and decreased food consumption at all dose levels were also observed. A maternal LOAEL of 

62.5 mg/kg/day and a developmental NOAEL of 500 mg/kg/day (highest dose tested [HDT]) 
Page 24 of 37

were established. A maternal NOAEL could not be determined at the lowest dose tested (LDT) 

of 62.5 mg/kg/day. TCM did not show developmental effects in a rabbit developmental study but 

produced statistically significant dose-related depressions in mean maternal body weights and 

decreased mean feed consumption (MRID 43614301). A maternal systemic toxicity LOAEL of 

30 mg/kg/day and a developmental NOAEL of 120 mg/kg/day (HDT) were established. No 

maternal NOAEL could be determined even at the LDT of 30 mg/kg/day. 

Reproductive Toxicity 

Based on the review of available data (e.g., subchronic and developmental studies), the database 

for reproduction is adequate to support TCM’s direct and indirect food uses. 

Chronic Toxicity 

Chronic toxicity studies are not expected to be needed since long-term duration exposure 

scenarios are not expected based on current registered uses of TCM. 

Carcinogenicity 

The need for carcinogenicity studies will be re-assessed following the agency’s review of the in 

vivo mutagenicity study expected to be required. 

Mutagenicity 

The agency reviewed the submitted gene mutation studies and found they are acceptable. TCM is 

positive for mutagenicity in Salmonella strains TA98 and TA100, with and without metabolic 

activation, in an Ames assay (MRID 42148801). It is also positive in an in vitro mammalian 

chromosomal aberration assay in Chinese hamster ovary (CHO) cells, with and without S9 

activation (MRID 42021801). In an unscheduled DNA synthesis (UDS) in mammalian cells test, 

no mutagenic response was observed in primary rat hepatocytes (MRID 42021701). 

The available in vitro data have shown positive results, and neither an in vivo mammalian bone 

marrow chromosomal aberration test nor an in vivo mammalian erythrocyte micronucleus test is 

available to examine the effect of TCM on an intact mammalian system. Additionally, there is 

indirect food-contact exposure, when TCM is used on food-contact surfaces and hand-to-mouth 

behavior on nonfood contact treated surfaces. To further evaluate mutagenicity and potential 

carcinogenicity of TCM via dietary exposure, the agency expects to require one of these in vivo

mutagenicity studies. 

Table 13 – Summary of Subchronic and Developmental Toxicity and Mutagenicity Data for 

TCM 

Guideline 

No. 

Study Type/Purity 

(%) MRID Results

Subchronic Toxicity
Page 25 of 37

Guideline 

No. 

Study Type/Purity 

(%) MRID Results

870.3100 

90-day Oral Study 

(Rodent) 

(technical grade 

TCM) 

43064301 

NOAEL = 30 mg/kg/day 

LOAEL = 150 mg/kg/day, based on the observation of 

histological lesions (engorgement of small blood vessels of the 

adrenal gland, brain, kidneys, liver, lung, and pituitary gland). 

Developmental Toxicity

870.3700 

Developmental 

Toxicity 

(TCM, 94.4%) 

43614301(Rabbit)

Systemic Toxicity NOAEL < 30 mg/kg/day (LDT) and LOAEL 

≤ 30 mg/kg/day, based on depressions in mean maternal body 

weights and decreased mean feed consumption values. 

Developmental toxicity NOAEL = 120 mg/kg/day (HDT) 

43614302 (Rat) 

Maternal NOAEL < 62.5 mg/kg/day (LDT) and LOAEL ≤ 62.5 

mg/kg/day, based on clinical signs at several or all dose levels 

(alopecia, gasping, altered respiration, salivation, lethargy, 

chromodacryorrhea), reduction in body weight gains, and 

statistically significant trends for decreased food consumption at 

all dose levels. 

Developmental toxicity NOAEL = 500 mg/kg/day (HDT) 

Mutagenicity Studies

870.5300 Ames Assay 

(TCM, 95.9%) 42148801 Positive result at 25 μg/plate for TA98 and TA100, both with and without metabolic activation. 

870.5375 

In vitro Mammalian 

Chromosomal 

Aberration Assay 

(TCM, 95.9%) 

42021801 Positive result at 50 μg/mL in Chinese hamster ovary (CHO) 

cells both with and without metabolic activation. 

870.5550 

In vitro Unscheduled 

DNA Synthesis 

(UDS) in Mammalian 

Cells 

(TCM, 95.9%) 

42021701 Negative result in primary rat hepatocytes. 

Notes: NOAEL = No Observed Adverse Effects Level; LOAEL = Lowest Observed Adverse Effects Level; NA = Not 

Applicable; LDT=Lowest Dose Tested; HDT=Highest Dose Tested 

Other Toxicological Effects 

As indicated in the environmental fate section (Appendix B ), TCM breaks down into 

hypochlorous acid and melamine in water; melamine is further degraded to ammeline and 

ammelide before yielding cyanuric/isocyanuric acid. Melamine is relatively stable and would be 

expected to remain as a residue on food contact surfaces. 

Melamine

Melamine was administered to Sprague–Dawley rats (Crl:CD [SD]VAF/Plus®; 6-7 weeks old) 

(8/sex/group) by gavage for 14 consecutive days, followed by an 8-day recovery period for the 

high-dose group, and monkeys were treated with melamine by gavage for 3 months, followed by 

a 4-week recovery period for the high-dose group (Early RJ, et al., 2012). Mortality was reported 

in the high-dose rats, as well as compound-related clinical signs (red urine), decreased body 

weights, and changes in clinical pathology (increased serum urea nitrogen and creatinine) and 

anatomical pathology (renal tubular cell debris, crystal deposition, and hyperactive regeneration 

of renal tubular epithelium) in the mid-dose rats. For the monkey study, the kidneys and/or liver 
Page 26 of 37

weights were increased in high-dose monkeys with increased serum alanine aminotransferase 

level, decreased red blood cell, hemoglobin, and hematocrit and increased reticulocyte counts 

with microscopic findings, and demonstrated increased extramedullary hematopoiesis in bone 

marrow, liver, or adrenals. Microscopic examination revealed nephrotoxicity, pericarditis, and 

increased hematopoiesis. Nephrotoxicity was also noted in mid-dose group. The NOAEL was 

determined to be 140 mg/kg/day (low dose) for rats following a 14-day oral administration and 

60 mg/kg/day (low dose) for monkeys in the 3-month study. 

Pregnant Sprague-Dawley rats administered melamine by gavage demonstrated maternal 

toxicity, including increased incidences of clinical signs and death, lower body weight gain and 

food intake, and increases in heart, adrenal gland and kidney weights, at the high-dose. 

Histopathological examinations revealed an increase in incidences of congestion, tubular 

necrosis/degeneration, crystals, casts, inflammatory cells in tubules, tubular dilation and tubular 

hyaline droplets in the maternal kidneys. Developmental toxic effects included a decrease in fetal 

weight, an increase in the incidence of skeletal variations, and a delay in fetal ossification; 

however, no histopathological changes were observed in fetal kidneys (one fetus/litter). The 

NOAEL was determined to be 400 mg/kg/day for both maternal and developmental toxicity 

(Kim SH, et al., 2011). 

An et al. (2010) investigated the hypothesis that melamine could impair cognitive function 

through impairment of hippocampal function. Male Wistar rats were administered melamine for 

four weeks at a dose of 300 mg/kg by oral gavage. The result of Morris water maze (MWM) 

testing showed a significant deficit in learning and memory in the melamine group compared to 

controls, and the field excitatory postsynaptic potentials (fEPSPs) slopes were significantly lower 

in the melamine group as well, as demonstrated by the long term potentiation (LTP) from 

Schaffer collaterals to CA1 region in the hippocampus test. 

Melamine and Cyanuric Acid 

Although melamine alone presents low toxicity in a range of species, available data showed that 

melamine and cyanuric acid together increased renal toxicity when co-ingested by animals. 

Renal failure and the presence of renal crystals were reported in studies in which cats were fed 

increasing amounts of melamine and cyanuric acid (Brown et al., 2007; Puschner et al., 2007). 

Such effects were confirmed in a study (Dobson et al., 2008) in which rats were administered 

ammeline or ammelide alone (both analogs of melamine), a mixture of melamine and cyanuric 

acid, and a mixture of all four compounds. The test results showed that neither ammeline nor 

ammelide alone produced any renal effects, but the mixtures produced significant renal damage 

and crystals in nephrons. Recent studies concluded the same findings at the high-dose level in 

rats, even after only 3 days exposure to melamine in combination with cyanuric acid (Park D, et 

al., 2011). 

Recently, a NOAEL of 2.1mg/kg bw/day for males and <2.6 mg/kg bw/day for females, and 

benchmark dose lower confidence limit (BMDL) values of 1.6 mg/kg bw/day for both sexes 

were established in a 28-day dietary study of co-exposure of melamine and cyanuric in F344 rats 

(Gamboa da Costa, G, et al., 2012). 
Page 27 of 37

Pharmacokinetics studies of melamine and cyanuric acid and their combinations in rats revealed 

that the pharmacokinetic profile was significantly altered when animals were administered equal 

amounts of melamine and cyanuric acid as a preformed melamine cyanurate complex, with 

reduced bioavailability of both compounds, lower observed maximum serum concentrations, 

delayed peak concentrations, and prolonged elimination half-lives (Jacob CC, et al., 2012). 

Additional studies (Pang J, et al., 2011) showed that animals co-administered equal amounts of 

melamine and cyanuric acid resulted in significant changes in toxicokinetic parameters of 

melamine, including lower maximum concentration and area under curve, higher plasma 

elimination half-life and volume of distribution, and significantly higher concentration of 

melamine in the kidneys, when compared with melamine alone group (P < 0.05). 

National Toxicology Program (NTP) Studies on Melamine and 

Cyanuric Acid 

When analyzing the outbreak of kidney failure and death of hundreds of cats and dogs in the 

USA caused by intentionally adulterating pet food with melamine and several degradates 

(including cyanuric acid), laboratory animals were exposed simultaneously to melamine and 

cyanuric acid. It was discovered that melamine cyanurate crystals formed and that these crystals 

occluded the nephron’s distal tubules which resulted in the nephrotoxicity observed in these 

animal species. 

An investigation of the high incidence of hospitalization of many infants and toddlers with 

nephrolithiasis (kidney stone), some with renal failure, and some confirmed deaths in China 

revealed that the cause was powdered infant formula intentionally adulterated with melamine. 

Human exposure to melamine and/or cyanuric acid from sources other than food are outlined in 

the NTP's document “NTP Research concept: melamine/cyanuric acid” 

(http://ntp.niehs.nih.gov/ntp/Noms/Final_ResConcept/Melamine_Cyanuric.pdf) as follows. 

(1) "Melamine resin, a hard thermosetting polymer made from melamine and formaldehyde, is 

widely used in the U.S. in the form of kitchenware, including plates, bowls, mugs and 

utensils.......leach considerable amounts of melamine monomer. A migration of up to 2.5 mg 

melamine/100 cm2 was observed under conditions that simulate an exposure to hot acidic foods"; 

(2) "Cyanuric acid is an FDA-accepted component of feed-grade biuret, a ruminant feed additive. 

The additive can legally contain up to 30% of cyanuric acid (and triuret)"; 

(3) "Cyanuric acid is used as a stabilizer and disinfectant in swimming pool water......the 

maximum allowable limits, dictated by state or local codes, are typically 100 ppm (National 

Swimming Pool Foundation (2007) Instructor Manual Certified Pool-SPA Operator Handbook, 

Appendices A-17. Available at http://www.nspf.com/Documents/CPOI_Manual_2007.pdf ) A 

study on the water ingestion during swimming activities in a pool indicates that the amount of 

water swallowed by non-adults (under 18 years old) was on average 37 mL and reached 154 mL. 

Considering this scenario and a cyanuric acid concentration of 100 ppm in a swimming pool, 

these volumes translate into an ingestion of up to 15.4 mg of cyanuric acid by non-adults. 

Furthermore, the possibility that non-professionally managed pools and hot tubs may 
Page 28 of 37

accidentally be treated with much higher concentrations of cyanuric acid should not be 

disregarded." 

The information outlined above indicated that there are a number of possible sources of exposure 

to melamine and cyanuric acid in the normal daily life of an average individual. In addition, the 

human food chain could be possibly indirectly or directly contaminated with melamine and/or its 

derivatives, including cyanuric acid. 

The National Toxicology Program (NTP) proposed to further investigate and determine: (1) the 

combined toxicological implications of a concurrent exposure of different species to melamine 

and derivatives, (2) the possible occurrence of biomarkers predictive of renal failure upon 

exposure to melamine and derivatives, and (3) the pharmacokinetics of melamine and cyanuric 

acid to better understand the full toxicokinetic profile of the individual triazines and their 

combinations. The studies, conducted with co-administration of melamine and cyanuric acid “in 

a phased manner”, are outlined in the final research proposal as follows: 

(1) “A pharmacokinetic study in rats with melamine and cyanuric acid when administered 

individually, in a time-staggered manner as a separate base and acid, simultaneously as a 

separate base and acid and simultaneously as a pre-formed compound (melamine cyanurate)” 

This study was completed and published (Jacob, CC, et al., 2012). 

(2) “28-day and 90-day studies in rats to determine the NOAEL of a combined treatment with 

melamine and cyanuric acid. Additional studies including an evaluation of systemic toxicity 

and/or specialized organ systems toxicity after long term (chronic) exposure will be considered 

following an evaluation of the subchronic study data.” The 28-day gavage study in rats was 

completed and published (Gamboa da Costa, G, et al., 2012). 

(3) “Metabolomic and proteomic early biomarkers of melamine + cyanuric acid-induced 

nephrotoxicity......by non-invasive methods.” 

(4) “Investigate the pharmacokinetics and determine the NOAEL of a combined exposure to 

melamine and cyanuric acid in a miniature pig model deemed to be representative of the human 

kidney anatomy and physiology.” 

The agency will be in contact with the NTP Project Leader to follow up with testing progress and 

obtain test results once available. 

 
Page 29 of 37

Appendix B Environmental Fate 

Environmental Fate Properties 

The agency has reviewed environmental fate data submitted in support of registration review 

from submitted OCSPP 835 laboratory studies, the EPI-WEB 4.1 program 

(http://www.epa.gov/oppt/exposure/pubs/episuitedl.htm), and the open literature. Many of these 

literature sources were included in the High Production Volume (HPV) submissions 

(http://www.epa.gov/hpv/pubs/summaries/tricltrz/c14659rs.pdf), while others were obtained 

directly from the Science Direct website (http://www.sciencedirect.com/), and the European 

Food Safety Authority (EFSA, http://dar.efsa.europa.eu/dar-web/provision, search for 

cyromazine). 

These data sources indicate that the parent compound TCM readily dechlorinates in water to 

form hypochlorous acid and the degradate melamine (CAS # 108-78-1, dechlorinated parent 

compound). As a result, environmental exposure to TCM from the registered uses will be 

minimal. In addition, environmental exposure to the TCM degradates is expected to be minimal 

based on the limited indoor use as a food or nonfood contact surface sanitizer and the further 

microbial degradation of TCM degradates. Melamine degrades by microbial action to sequential 

metabolites ammeline (CAS # 645-92-1, once-deaminated and hydroxylated melamine), 

ammelide (CAS # 645-93-2, twice-deaminated and hydroxylated melamine), and 

cyanuric/isocyanuric acid (CAS # 108-80-5, deaminated melamine with three hydroxyl groups), 

biuret (CAS # 108-19-0, two urea molecules combined), and urea (CAS # 57-13-6) which 

ultimately degrades to form ammonia (NH3) and carbon dioxide (CO2). Other than biuret and 

urea, all of the above compounds contain a symmetric triazine ring. Cyanuric/isocyanuric acids 

are tautomers with readily-interchangeable keto and enol groups, depending on the pH. 

TCM and its degradates/metabolites are highly water soluble, weakly sorbed, and will be in the 

water phase in both soil and wastewater treatment plants (WWTPs). Melamine and its 

metabolites do not degrade under abiotic conditions (presence of water and/or light without 

microorganisms). However, the metabolites containing the triazine ring are more degradable 

under anaerobic conditions in the presence of microorganisms (acclimated or unacclimated) or 

when acclimated microorganisms are present under aerobic conditions. The degradation pathway 

of TCM leads to the formation of CO2 and NH3; which are released into the air or incorporated 

into microbial biomass. The environmental fate properties of TCM, its metabolites, and related 

compounds are summarized in Table 14. 

Figure 2 illustrates the degradation pathway for a number of compounds with a symmetric 

triazine ring (including melamine) to form cyanuric/isocyanuric acid. As a result, environmental 

fate of these compounds depends on the environmental fate of cyanuric acid. 

Cyanuric/isocyanuric acid is not prone to abiotic degradation (hydrolysis or phototolysis) and is 

more resistant to degradation under aerobic conditions or in the presence of unacclimated 

microbes. However, anaerobic conditions or acclimated microbes facilitate its eventual 

degradation to CO2 and NH3. 
Page 30 of 37

Figure 2 – Formation and Decline of Cyanuric Acid from Compounds with a Symmetric 

Triazine Ring. 

TCM and Metabolites 

TCM and its metabolites melamine, ammeline, ammelide, and cyanuric/isocyanuric acid share a 

symmetric triazine ring with s-triazine herbicides (e.g. atrazine, simazine) and an insect growth 

regulator (cyromazine). However, TCM and its metabolites are not to be confused with 

agronomic herbicides that are classified as s-triazine compounds which have alkyl side chains, 

and therefore, it is not considered as part of the triazine cumulative assessment (See Section 3.4.2 

above). Therefore, a total toxic residue approach, as would be used for s-triazine compounds, 

will not be applied to assess environmental exposure. 

TCM (parent compound) is registered as a food-contact sanitizer and disinfectant with indoor 

uses and produces hypochlorous acid (an oxidizing agent) when dissolved in water. 

Hypochlorous acid is a weak acid (pKa (dissociation constant) of 3.7 x 10-8 at 25 °C). Based on 

this pKa, 50% will be in hypochlorous acid form (HOCl) and 50% will be in hypochlorite ion (-

OCl) form at pH 7.4 (pH = -log10 (3.7 x 10-8). As the pH increases above 7.4, the amount of 

hypochlorite ion present will increase. Conversely, as the pH decreases below pH 7.4, the 

amount of hypochlorous acid present will increase. Hypochlorous acid reacts readily with 

ammonia, amines, sulfides, sulfites, and nitrites present in the water. Antimicrobial activity 

results from the oxidation reactions with microbial enzyme systems. These oxidation reactions 

consume residual free chlorine, with the concurrent reduction of hypochlorous acid/hypochlorite 

to chloride anions. However, the release of hypochlorous acid is reversible and it can reattach to 

the melamine, ammeline, ammelide, and cyanuric acid molecules if additional free hypochlorous 

acid is added. 

Cyromazine

Atrazine

Simazine

Formation and Decline of Cyanuric Acid from 

Compounds with Symmetric Triazine Ring

Chlorinated 

Isocyanurates

Melamine

Trichloromelamine

Ammeline

Ammelide

Cyanuric/Isocyanuric Acid

Biuret

Urea

CO2 NH3
Page 31 of 37

The TCM degradates, cyanuric acid and isocyanuric acid (dechlorinated parent compound) exist 

in a pH-dependent equilibrium. These two acids are keto/enol tautomers which interconvert 

readily depending on the pH of the environment. The cyanuric acid (enol form with three 

hydroxyl groups (-OH) attached to triazine ring) is the primary form found at lower pH values, 

while the isocyanuric acid (keto form, with three oxygens double-bonded with triazine ring) 

would be found at higher pH values. The pKa values for cyanuric acid are 6.88, 11.4, and 13.5 

(http://www.drugfuture.com/chemdata/cyanuric-acid.html ). For more details, please see Table 

14. 
Docket Number EPA-HQ-OPP-2012-0682 

www.regulations.gov 

Page 32 of 37

Table 14 – Environmental Fate Data for TCM and Related Compounds Containing a Symmetric Triazine RTest Guideline (Number) 

Test Substance Result Reference Comment 

Hydrolysis (835.2120) 

Isocyanuric acid and sodium isocyanurate 

Rapid degradation to cyanuric acid Hu, 19822

MRID 00056479 

Cyanuric acid was stabpp. 10-12 of HPV docu

Photodegradation in Water (835.2240) 

Monosodium cyanurate 

Rapid degradation to cyanuric acid from hydrolysis (no photodegradation)_ 

Hu, 19822

MRID 00056479 

Cyanuric acid was stabpp. 10-12 of HPV docu

Batch Equilibrium (835.1230, OECD 106) 

Cyanuric acid Average Koc of 51 ml/g Michael and 

Cummings, 19823

Similar to OECD 106 

Unknown Cyanuric acid Aerobic Conditions: Degrades slowly under aerobic 

conditions. Some microorganisms can degrade cyanuric acid if acclimated and organic nutrients are present Anaerobic conditions: Readily biodegradable 

Zeyer et al., 19804

Cyanuric acid formed 

p. 15 of HPV documen

Unknown Cyanuric acid Aerobic conditions: 30 and 15% degradation of 

cyanuric acid in 48 h for Pseudomonas sp. And 

Achromobacter sp. (mesophilic bacteria) 

Ernst and Rehm. 19905

Cyanuric acid formed 

pp. 17-18 of HPV docuBacteria isolated from 

Unknown Cyanuric acid Aerobic conditions: 58% degradation of cyanuric acid 

in 8 days in FeS medium under aerobic conditions Anaerobic conditions: 100% degradation of cyanuric acid in 4 days under anaerobic conditions in cysteine medium 

Jessee et al., 19836

Unknown bacterium frsediment downstream treats wastewater from manufacturing facility Cyanuric acid formed 

pp. 19-20 of HPV docu

Unknown Cyanuric acid Anaerobic conditions: 100% degradation of triazine 

ring when additional source of nitrogen was present No cell growth in absence of additional nitrogen source 

Cook et al., 19857

Pseudomonas NRRL BKlebsiella pneumoniae 

Cyanuric acid formed 

pp. 21-22 

Unknown Cyanuric acid Aerobic conditions: 100% degradation after 8 h (aerated 

activated sludge, 2.5 mg/l O2); 42% degradation after 9 h 

(aerated activated sludge, 8.7 mg/l O2); 0% degradation 

(highly aerobic system, O2 concentration not specified) 

Anaerobic conditions: 25-50% degradation in 48 h and 100% in 72 h (sewage); 95-98% degradation in 72 h (nutrient broth); 52-100% degradation in 9-23 days (6 soils and muds) 

Saldick, 19748 Cyanuric acid formed 

pp. 22-23 of HPV docu
Page 33 of 37

Test Guideline (Number) 

Test Substance Result Reference Comment 

Unknown Cyanuric acid 100% degradation in unknown time Sisodia et al., 

19969

Degradation of cyanurof nitrogen when triazipresent Cyanuric acid formed 

pp. 24-25 of HPV docu

Unknown Cyanuric acid BOD5 and COD of 6.5 and 11 mg/l Unknown 

reference, possibly Zeyer et al., 19804

p. 15 of HPV documen

Aerobic Aquatic Metabolism (835.4300) 

Atrazine 70-80% of atrazine mineralization in constructed wetland 

fed by river draining treated corn fields; Wetland water demonstrated 60-80% of atrazine mineralization in one month; 75-81% mineralization in river water samples containing acclimated microorganisms; Cedar bog did not demonstrate mineralization of atrazine because microorganisms were not adapted 

Anderson et al., 200210

Atrazine totally mineraconstructed wetland thmicroorganisms that ardegradation of triazine Atrazine did not mineracclimated microorganCO2 and NH3

None Numerous 

triazine herbicides 

Cyanuric acid was end product (degradate) of S-triazines that reached WWTPs and was not degraded significantly

Kontchou and Gschwind, 199811

Mixed culture of microtest. 

None Melamine resin 85 and 54% of melamine in sludge degraded by 84 days 

in waste paper and plant residue compost, respectively. Initial melamine concentration of 200 mg/kg dry matter; Clumps of melamine resin slowed degradation process; Half-lives of melamine in waste paper and plant residue composts were 45 and 84 days, respectively. Sequential degradates ammeline, ammelide, and cyanuric acid reached up to 150, 2,400, and 4,000 mg/kg dry matter (ammelide and cyanuric acid degraded slower than the 

pile shrank) 

Tian et al., 201212

Composting study usinwaste paint sludge (WMelamine resin (melampolymer that can exist rubber13 and can be us

products, adhesives, an

Temperatures reached 

study (thermophilic phbetween 25 and 40 oC 

(mesophilic phase). Rates were 0, 20 and 1compost and 20 and 10compost Both composts increascucumber (Cucumis sa

sativus), and lettuce (L
Page 34 of 37

Test Guideline (Number) 

Test Substance Result Reference Comment 

None Melamine 

formaldehyde resin 

Melamine degraded 73-95% and 55-74% in inoculated vs uninoculated compost, respectively. Melamine concentrations increased in the thermophilic phase because degradation was slower than pile shrinkage. Degradate ammeline formed and degraded quickly to 

degradates ammelide and cyanuric acid in thermophilic phase. Ammelide and cyanuric acid degradation slower than pile shrinkage (leading to higher concentrations). 

Melamine degraded more slowly in uninoculated compost than in inoculated compost (Mesophilic phase). Ammeline degraded quickly in mesophilic phase to ammelide and cyanuric acid which degraded faster in inoculated conditions 

Tian et al., 201215

Temperatures reached 

study for 91 days (therstayed at 30 oC (86 oF) 

phase). Study had moswhich concentrated meby 91 days of thermop

None Atrazine Atrazine degradation (removal of side chains) occurred 

primarily by fungi. Atrazine degradation did not occur in absence of functional bacteria or fungi 

Levanon, 199316

Delanco silt loam soil field with acclimated o

None Melamine, 

Cyanuric acid, Deethyl simazine 

Complete (100%) mineralization of melamine, cyanuric acid, and deethyl simazine (triazine herbicide) as sole source of nitrogen in fluidized bed for waste-specific 

treatment 

Hogrefe et al., 198517

Pseudomonas sp. (mesprimary removal organ

835.4100 Melamine from 

applied cyromazine 

Half-lives of 88-217 days in laboratory aerobic soil (topsoil) at 20 oC 

European Food Safety Authority (EFSA), vol. 118

Aerobic soil metabolisoxygenated conditionssymmetric triazine useregulator; CO2 and non

were primary degradatthat mineralization of isuch as ammeline, ammwas complete 

835.4200 Melamine from 

applied cyromazine 

Slower mineralization of cyromazine in laboratory anaerobic soil metabolism studies with no detectable melamine 

European Food Safety Authority (EFSA), vol. 118

Anaerobic soil metabofollowing rain); Cyromtriazine used as an inseunder sterile conditionwere produced indicatoccurred 
Page 35 of 37

Test Guideline (Number) 

Test Substance Result Reference Comment 

835.6100 Melamine from 

applied cyromazine 

Half-lives of 24-54 days in terrestrial field dissipation studies in Canada and Europe (colder climate); Median and 90th percentile half-lives of 31 and 52 days, 

respectively 

European Food Safety Authority (EFSA), vol. 118

Cyromazine is a symmfor use as an insect gro

1. http://www.epa.gov/hpv/pubs/summaries/tricltrz/c14659rs.pdf 

2. H. Hu (1981) Hydrolysis study of aqueous sodium salt solutions of 2,4,6-trihydroxy-1,3,5-triazine. Princeton Chemical Research and Development Centre. MRID 003. Michael, P., and Cummings, I., “Cyanuric Acid Absorption On Soils”, Monsanto Report ES-82-SS-94, December, 1982. Method: OECD 106. 

4 An Index of Refractory Organics, T. Helfgott, F. Hart and R. Bedard, EPA 600/2-77-174, 1977, pp. 1-7, 24-25. Process for the biological degradation of cyanuric acid

Mayer, UK Patent App. 2,025,919 (Jan. 30, 1980). 

5 Degradation of Cyanuric Acid by Immobilized Bacteria, C. Ernst and H. Rehm, DECHEMA Biotechnol. Conf., 4(Pt. A), 1990, 577-580. Method: J. Biol. Chem. 195

6 Anaerobic Degradation of Cyanuric Acid, Cysteine, and Atrazine by a Facultative Anaerobic Bacterium, J. Jessee, R. Benoit, A. Hendricks, G. Allen, and J. Neal, Ap

1983, 45(1) 97-102. Method : J. Water Pollution Control Fed., 39, 181-187 (1967); J. Water Pollution Control Fed., 40, 306-319 (1968) 

7 Ring cleavage and degradative pathway of cyanuric acid in bacteria, A. Cook, P. Beilstein, J. Grossenbacher, and R. Hütter, Biochem. J., 1985, 231, 25-30. Method: 

39, 181-187 (1967); J. Water Pollution Control Fed., 40, 306-319 (1968) 

8 Biodegradation of Cyanuric Acid, J. Saldick, Applied Microbiology, 1974, 28(6) 1004-1008. Method: (1967) J. Water Pollut. Contr. Fed. 39:181-187; Biodegradabil

from rivers. (1963) Proc. 18th Ind. Waste Conf. Purdue Univ. 115:278-282. 

9 Continuous Culture Biodegradation of Simazine’s Chemical Oxidation Products, S. Sisodia, A. Weber, and J. Jensen, Water Research, 1996, 30(9) 2055-2064. Meth

was investigated as a function of continuous culture process growth rate. 

10 Anderson, K.L., K.A. Wheeler, J.B. Robinson, and O.H. Tuovinen. 2002. Atrazine Mineralization Potential in Two Wetlands. Water Research 36(2002): 4785-4794. 

11 Kontchou, C.Y and N. Gschwind. 1999. Biodegradation of S-Triazine Compounds by a Stable Mixed Bacterial Community. Ecotoxicology and Environmental Safety 

12 Tian, Y., L. Chen, L. Gao, F.C. Michel, Jr., H.M. Keener, M. Klingman, and W.A. Dick. 2012. Composting of waster paint sludge containing melamine resin and the 

growth and soil water quality. J. Hazard. Mater. http://dx.doi.org/10.1016/j.jhazmat.2012.09.013. (Article in press) 

13 http://en.wikipedia.org/wiki/Thermosetting_plastic 14 http://www.thefreedictionary.com/melamine+resin 15 Tian, Y., L. Chen, L. Gao, F.C. Michel, Jr., C. Wan, Y. Li, W.A. Dick. 2012. Composting of waster paint sludge containing melamine resin as affected by nutrients an

microbial inoculation. Environmental Pollution 162:129-137. 

16 Levanon, D. 1993. Roles of fungi and bacteria in the mineralization of the pesticides atrazine, alachlor, malathion, and carbofuran in soil. Soil Biol. Biochem. (25):10

17 Hogrefe, W., H. Grossenbacher, Y. Kido, A.M. Cook., and R. Hutter. 1985. Biodegradation in a fluidized bed of real wastes containing s-triazines. Conservation and 

18 http://dar.efsa.europa.eu/dar-web/provision (search for cyromazine) 
Page 36 of 37

Hypochlorous Acid17

TCM is used as a water solution which forms melamine and hypochlorous acid (HClO), an 

oxidizing agent and the biocidal agent. HClO is a weak acid and, depending upon pH, can 

further disassociate into a hydrogen ion and a hypochlorite ion (ClO-

), in a reversible reaction. 

The antimicrobial activity of chlorine compounds depends primarily on HClO which can rapidly 

cross cell membranes. While ClO-

 has some disinfection potential it requires longer contact time. 

It is HClO and ClO-

 that are the active disinfecting moieties of TCM. 

HClO

ு௬௣௢௖௛௟௢௥௢௨௦ ௔௖௜ௗ

՞ H+

ு௬ௗ௥௢௚௘௡ ௜௢௡

൅ ClO-

ு௬௣௢௖௛௟௢௥௜௧௘ ௜௢௡

 Eqn. 1 

The acid dissociation constant (Kdiss or Ka) of HClO is 3.4 x 10-8 (or pKa

18 = 7.7). Hence at any 

given time, the concentration of HClO is not very high; however, as it is consumed, more HClO 

is formed. It also means that at pH 7.7, the ratio of HClO to ClO- is 50:50. A literature report 

(Connell, 1996) estimated the changes due to protolysis (hydrolysis) of a solution containing 

ClO-. The graphical data is converted into the numerical data on the percent of HClO and ClOfrom pH 4 to 11 as shown in Table 15. In dilute aqueous solutions these reactions occur rapidly. 

Table 15 – Changes in Protolysis (Hydrolysis) of Solutions Containing Hypochlorite Ion. 

pH % HClO % ClO4.0 100 0 

6.3 95 5 

7.2 70 30 

7.7 50 50 

8.0 21 79 

11 0 100 

Disinfection is more efficient at lower pH than at higher pH because HClO is a more efficient 

disinfectant than ClO-

, and as indicated above there is a higher proportion of HClO at lower pH 

than at higher pH values. 

Available chlorine (AC) is a measure of the equivalent weights of oxidizing agents, with chlorine 

gas as a basis—i.e., normalizes chlorine-containing compounds to allow comparison of oxidizing 

potential. The concentration of hypochlorite (or any other oxidizing disinfectant) may be 

expressed as available chlorine by determining the electrochemical equivalent amount of 

elemental chlorine (Cl2) to that compound (USEPA 1986). 

A mole of chlorine gas reacts with water to form a mole of HClO and a mole of protons (or 

hydrogen ions) and a mole of chloride ions. The oxidation state of chlorine is 0 in chlorine gas, 

+1 in HClO and -1 in Cl-

, therefore chlorine is both oxidized and reduced in this reaction. 

Cl2

஼௛௟௢௥௜௡௘,௚௔௦

൅ H2O

ௐ௔௧௘௥

՜ HClO

ு௬௣௢௖௛௟௢௥௢௨௦ ௔௖௜ௗ

൅ H+

ு௬ௗ௥௢௚௘௡ ௜௢௡

൅ Cl-

஼௛௟௢௥௜ௗ௘ ௜௢௡

 Eqn. 2 

 

17 Details regarding Hypochlorous Acid can be viewed in the Na & Ca Hypochlorite Registration Review Docket at 

http://www.regulations.gov in docket EPA-HQ-OPP-2012-0004. 18 pKa = -log10Ka
Page 37 of 37

Elemental Cl2 oxidizing potential: one mole of elemental chlorine is capable of reacting with two 

electrons to form inert chloride, as shown in the reaction equation below (USEPA, 1986). The 

AC is 70.91 grams per mole (identical to the molecular weight of Cl2). 

Cl2

஼௛௟௢௥௜௡௘

൅ 2݁ି

ா௟௘௖௧௥௢௡௦

ൌ 2Cl-

஼௛௟௢௥௜ௗ௘ ௜௢௡

 Eqn. 3 

ClO-

 oxidizing potential: one mole of ClO- may react with two electrons to form chloride, as 

shown in the reaction equation below. Hence, one mole of hypochlorite is equivalent 

(electrochemically) to one mole of elemental chlorine, and may be said to contain 70.91 grams of 

AC (identical to the molecular weight of Cl2) (USEPA, 1986). 

ClOି

ு௬௣௢௖௛௟௢௥௜ௗ௘

൅ 2݁ି

ா௟௘௖௧௥௢௡௦

൅ 2H+

ு௬ௗ௥௢௚௘௡ ௜௢௡

ൌ Cl-

஼௛௟௢௥௜ௗ௘ ௜௢௡

൅2H2O

ௐ௔௧௘௥

 Eqn. 4 

Chlorine, in addition to providing disinfection or oxidation of microorganisms, is consumed 

through oxidation or substitution reactions with inorganic substances such as ammonia, iron, 

manganese, sulfides and some other organic substances (e.g., phenols). 

In the surface water and wastewater streams, possible transformation products like chlorine, 

HOCl, and ClO3

-

 may be present, but the determination of exact amounts of these moieties 

cannot be calculated as these will depend on environmental conditions (e.g., pH of the medium, 

temperature, ionic strength).