Page 2 of 52

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 ..................................................................................................... 9

1.4.1 Registrations ............................................................................................................. 9

1.4.2 Summary of Registered Uses .................................................................................. 10

1.4.3 Usage Information .................................................................................................. 12

1.5 Regulatory History ......................................................................................................... 12

1.5.1 Recent/Pending Regulatory Actions ....................................................................... 12

1.5.2 Tolerance Information ............................................................................................ 12

1.6 Incidents ......................................................................................................................... 12

1.6.1 Human Health ......................................................................................................... 12

1.6.2 Ecological ............................................................................................................... 14

2 Anticipated Data Needs ........................................................................................................ 14

3 Human Health Risk Assessment ........................................................................................... 17

3.1 Existing Toxicological Endpoints .................................................................................. 17

3.2 Dietary Exposure ............................................................................................................ 18

3.2.1 Food ........................................................................................................................ 18

3.2.2 Drinking Water ....................................................................................................... 19

3.3 Occupational and Residential (ORE) Exposures ........................................................... 19

3.3.1 ORE Exposure Assessed in the RED ...................................................................... 19

3.3.2 ORE Exposures Assessed after the RED ................................................................ 19

3.3.3 ORE Exposures that will Need to Be Assessed for Registration Review ............... 20

3.4 Aggregate and Cumulative Exposure ............................................................................. 21

3.4.1 Aggregate Exposures .............................................................................................. 21

3.4.2 Cumulative Exposures ............................................................................................ 21

4 Environmental Risk Assessment........................................................................................... 21

4.1 Environmental Conceptual Model Exposure Pathways ................................................. 21

4.2 Ecological Effects Assessment ....................................................................................... 25
Page 3 of 52

4.2.1 Mechanism of Action .............................................................................................. 25

4.2.2 Measures of Effect (Ecotoxicology Endpoints) ...................................................... 26

4.3 Exposure Analysis Plan .................................................................................................. 27

4.3.1 Aquatic and Terrestrial Wildlife Exposure Estimates ............................................ 27

4.3.2 Down-the-Drain Analysis ....................................................................................... 27

4.4 Effects Analysis Plan ..................................................................................................... 28

5 Endocrine Disruptor Screening Program (EDSP) ................................................................. 28

6 Guidance for Commenters .................................................................................................... 29

6.1 Preliminary Work Plan ................................................................................................... 29

6.1.1 Trade Irritants .......................................................................................................... 29

6.1.2 Water Quality .......................................................................................................... 29

6.1.3 Environmental Justice ............................................................................................. 30

6.1.4 Structure Activity Relationships ............................................................................. 31

6.1.5 Additional Information ........................................................................................... 32

7 Next Steps ............................................................................................................................. 32

8 References ............................................................................................................................. 32

Appendix A: Environmental Fate ................................................................................................. 34

Appendix B: Toxicology Profile ................................................................................................... 43

Appendix C: Ecotoxicology Profile .............................................................................................. 45

List of Tables 

Table 1 - Summary of Anticipated Risk Assessments and Data Needs ......................................... 6

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

Table 3 - Chemical Identification Information for the Chlorinated Isocyanurates ......................... 8

Table 4 – Physical and Chemical Properties for the Chlorinated Isocyanurates ............................ 8

Table 5 - Distribution of Products by Specific Chlorinated Isocyanurate ...................................... 9

Table 6 – Summary of Chlorinated Isocyanurate Antimicrobial Uses ......................................... 10

Table 7 - Incidents Reported for the Chlorinated Isocyanurates .................................................. 13

Table 8 - Studies Anticipated as Needed for the Registration Review of the Chlorinated 

Isocyanurates................................................................................................................................. 15

Table 9 – Existing Toxicology Endpoints .................................................................................... 17

Table 10 - Occupational Exposure Scenarios for the Chlorinated Isocyanurates ......................... 20

Table 11 – Existing Ecological Effects Endpoints ....................................................................... 26
Page 4 of 52

Table 12 Environmental Fate Data for Chlorinated Isocyanurates (di- and tri-chloro) ............... 37

Table 13 - Acute Toxicity of the Chlorinated Isocyanurates ........................................................ 43

Table 14 Available Endpoints from Avian Ecotoxicity Studies for Trichloro-s-triazinetrione ... 46

Table 15 Available Endpoints from Avian Ecotoxicity Studies for Sodium Dichloroisocyanurate 

Dihydrate....................................................................................................................................... 46

Table 16 Available Endpoints from Avian Ecotoxicity Studies for Sodium Dichloro-sTriazinetrione ................................................................................................................................ 47

Table 17 Available Acute Endpoints from Freshwater Fish and Aquatic Invertebrate Ecotoxicity 

Studies for Trichloro-s-triazinetrione ........................................................................................... 49

Table 18 Available Acute Endpoints from Freshwater Fish and Aquatic Invertebrate Ecotoxicity 

Studies for Sodium Dichloro-s-Triazinetrione .............................................................................. 49

Table 19 Available Acute Endpoints from Freshwater Fish and Aquatic Invertebrate Ecotoxicity 

Studies for Sodium Dichloroisocyanurate Dihydrate ................................................................... 50

Table 20 Available Acute Endpoints from Freshwater Fish and Aquatic Invertebrate Ecotoxicity 

Studies for Potassium Dichloroisocyanurate ................................................................................ 50

Table 21 - Available Aquatic Organism data for Isocyanuric Acid ............................................. 51

List of Figures 

Figure 1 Conceptual Model for Ecological Exposure and Effects of Chlorinated Isocyanurates 

and their Reaction Products/Degradates from Sanitizing and Disinfecting Uses for Laundry and 

Hard Surfaces to Aquatic and Terrestrial Organisms ................................................................... 22

Figure 2 Conceptual Model for Ecological Exposure and Effects of Chlorinated Isocyanurates 

and their Reaction Products/Degradates from Swimming Pool and Water Bed Uses to Aquatic 

and Terrestrial Organisms ............................................................................................................. 23

Figure 3 Conceptual Model for Ecological Exposure and Effects of Chlorinated Isocyanurates 

and their Reaction/Degradates from Cooling Water Tower Uses to Aquatic and Terrestrial 

Organisms ..................................................................................................................................... 24

Figure 4 Conceptual Model for Ecological Exposure and Effects of Chlorinated Isocyanurates 

and their Reaction/Degradates from the Use and Disposal of In-Can or In-Container Material 

Preservatives to Aquatic Organisms ............................................................................................. 25

 
Page 5 of 52

1 Introduction 

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 the U.S. 

Environmental Protection Agency (USEPA, EPA, or the Agency) 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 Chlorinated Isocyanurates Case. 

Documents associated with this registration review can be viewed at www.regulations.gov in 

docket EPA-HQ-OPP-2012-0794. Below is a summary of the issues relevant to this registration 

review case. 

 
Page 6 of 52

Table 1 - Summary of Anticipated Risk Assessments and Data Needs 

Risk Assessment 

Assessment 

Necessary to 

Support 

Registration 

Review 

Date of Most 

Recent 

Assessment 

Type of 

Assessment 

Required 

(New/Updated) 

Data Needed 

Dietary (food) Yes None New Food-handling, Migration 

Studies1

Dietary (drinking water) Yes 3/26/2001 Updated None 

Occupational Handler 

(Inhalation Exposure) Yes None New Inhalation Indoor Exposure Data2 

Residential Handler 

(Inhalation Exposure) Yes None New Inhalation Indoor Exposure Data3 

Residental Post Application, 

Swimming Pools 

(Incidental Oral Exposure) 

Yes 2/26/2001 Updated None 

Residental Post Application, 

Disinfected Floors 

(Incidental Oral Exposure) 

Yes None New Surface Residue Data 

Aggregate Exposures Yes None New None 

Cumulative Exposures No None None None 

Ecological Yes None4 New 

Aquatic plants vascular and 

non-vascular, ASRI, Aquatic 

metabolism, WWTP 

biodegradation study

1. Residue chemistry data are anticipated as needed to determine dietary exposure to cyanuric acid/isocyanuric acid following 

sanitization of food contact surfaces of food processing plants (including dairies) and food-handling facilities (including public 

eating places), adhesive preservation, and slimicide use in the pulp slurry to make paper/paperboard for food contact. 

2. Indoor exposure data are anticipated as needed for the following occupational handler scenarios: 1- Open pour liquids, 

granules and powder for hard surface disinfection and pool treatment; 2- Open pour granules for material preservation; 3- Mop, 

wipe and trigger spray for hard surface disinfection; 4- Hand wand spray disinfection of egg and food processing plants; 5- 

Fogging disinfection of egg and food processing plants; and 6- Brush, roller and spray application of preserved paints. 

3. Indoor exposure data are needed for the following residential handler scenarios: 1- Open pour liquids, granules and powder for 

pool treatment; 2- Mop, wipe and trigger spray for hard surface disinfection; and 3- Brush, roller and spray application of 

preserved paints. 

4. A hazards assessment was done in the 1992 RED, but no risk assessment was conducted. 

Table 2 - Anticipated Registration Review Schedule 

Anticipated Activity Target Date1 Completion Date

Phase 1: Opening the Docket 

Open Docket and 60-Day Public Comment for Preliminary Work 

Plan 2012-12 2012-12-19 

Close Public Comment Period 2013-02 

Phase 2: Case Development 

Issue Final Work Plan 2013-06 

Issue Data Call-In (DCI) 2014-06 
Page 7 of 52

Anticipated Activity Target Date1 Completion Date

Receive Data to be Considered in Risk Assessment 2016-06 

Open 30-Day Public Comment Period for Preliminary Risk 

Assessment(s) 2017-12 

Close Public Comment Period 2018-01 

Phase 3: Registration Review Decision and Implementation 

Open 60-Day Public Comment Period for Proposed Decision 2018-06 

Close Public Comment Period 2018-08 

Issue Final Decision 2018-12 

Begin Post-Decision Follow-up 2018 

Total (years) 6 

1

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

Program with respect to the active ingredients in this case). 

1.2 Case Overview 

The docket for the Chlorinate Isocyanurates Case (Case 0569) has been established at 

http://www.regulations.gov in docket number EPA-HQ-OPP-2012-0794. Except where 

otherwise noted, the five active ingredients in this case will be referred to collectively as 

“chlorinated isocyanurates.” 

The dechlorinated s-triazinetrione, isocyanuric acid (PC Code: 081402) is not being considered 

in this registration review. No registered pesticide products contain dechlorinated striazinetrione, isocyanuric acid as an active ingredient. Although initially considered as part of 

the Chlorinated Isocyanurates case, potassium dichloro-s-triazinetrione (PC Code: 081403) was 

never registered by EPA in any pesticide products and, therefore, will not be evaluated as part of 

this registration review. Although the penta-s-triazinetrione (PC Code: 081406) was considered 

in the 1988 Registration Standard, it was not included in the 1992 Reregistration Eligibility 

Document1

 and is not included in this registration review action since no registered products 

remain with the Agency. 

The chlorinated isocyanurates and triazine herbicides share a symmetric triazine ring. However, 

the chlorinated isocyanurates are not to be confused with agronomic herbicides that are classified 

as s-triazine compounds which have alkyl side chains, and, therefore, the chlorinated 

isocyanurates are not considered as part of the triazine cumulative assessment. 

1.3 Chemical Identification and Properties 

Table 3 presents the four active ingredients to be assessed in Case 5069: dichloro-s-triazinetrione 

(PC Code: 081401); sodium dichloro-s-triazinetrione (PC Code: 081404); trichloro-s-

 

1

 Environmental Protection Agency, 1992. Reregistration Eligibility Document (RED) Chlorinated Isocyanurates 

http://www.epa.gov/pesticides/reregistration/REDs/old_reds/chlorinated_isocyanurates.pdf 
Page 8 of 52

triazinetrione (PC Code: 081405); and sodium dichloro-s-triazinetrione dihydrate (PC Code: 

081407). All of these substances are substituted chlorinated salts or acids of isocyanuric acid 

((CNOH)3) and act as chlorine releasers; they are hereinafter collectively referred to in this 

document as chlorinated isocyanurates. 

Table 3 - Chemical Identification Information for the Chlorinated Isocyanurates 

Chemical Name Dichloro-s-triazinetrione Sodium dichloro-striazinetrione Trichloro-s-triazinetrione Sodium dichloro-striazinetrione dihydrate 

Common Name Dichloroisocyanuric acid Sodium dichloroisocyanurate Trichloroisocyanuric acid Sodium dichloroisocyanurate 

dihydrate 

Synonyms 

l,3-Dichloro-s-triazine2,4,6 (lH,3H,5H) trione l,3-Dichloro-s-triazine-2,4,6 

(lH,3H,5H) trione sodium salt

1,3,5-trichloro-s-triazine2,4,6 (lH,3H,5H) Trione 1,3-Dichloro-s-triazine-2,4,6 

(1H,3H,5H) trione sodium salt 

dihydrate 

Trade Names ACL 70; CDB 70 ACL 60; CDB 60; S.D.I.C. ACL 90 Plus; CDB 85; 

T.I.C.A.; TCCA. ACL 56; DICD 

PC Code 081401 081404 081405 081407 

CAS No. 2782-57-2 2893-78-9 87-90-1 51580-86-0 

Chemical 

Family Halogenated triazines 

Molecular 

Formula C3HN3O3Cl2 C3N3O3Cl2Na C3N3O3Cl3 NaC3N3O3Cl2.2H2O 

Molecular 

Weight 198.98 220.96 232.42 255.98 

Available 

chlorine % 

Theoretical 

Nominal 

70.0 - 71.64 60.0 - 64.48 85.0 - 91.5 55.0 % - 57.0 

Molecular 

Structures: 

The chlorinated isocyanurates product chemistry relevant to risk assessment is presented in Table 

4 and details of the fate properties are discussed in Appendix A. 

Table 4 – Physical and Chemical Properties for the Chlorinated Isocyanurates 

OPPTS Guideline No./ 

Physical and Chemical 

Properties 

Dichloro-striazinetrione Sodium dichloro-striazinetrione Trichloro-striazinetrione Sodium dichloro-striazinetrione dihydrate

830.1550 

Product identity and 

composition 

Refer to Table 1. Refer to Table 1. Refer to Table 1. Refer to Table 1. 

830.6302/Color White White White White 

830.6303/Physical State Crystalline solid Granular 

Crystalline solid Crystalline solid Crystalline solid 

830.6304/Odor Chlorine Chlorine Chlorine Chlorine 

830.6313 

Stability to sunlight, normal 

and elevated temperature, 

metals/metal ions 

Stable and relatively inert 

when dry 

Stable and relatively inert 

when dry 

Stable and relatively inert 

when dry 

Stable and relatively inert 

when dry 
Page 9 of 52

OPPTS Guideline No./ 

Physical and Chemical 

Properties 

Dichloro-striazinetrione Sodium dichloro-striazinetrione Trichloro-striazinetrione Sodium dichloro-striazinetrione dihydrate

830.6314 

Oxidation/Reduction: Strong Oxidizing material Strong Oxidizing material Strong Oxidizing material Strong Oxidizing material

830.7000/pH 2.6 (saturated solution) 6.1 (1% solution) 2.9 (1% solution) 6.4 (1% solution) 

830.7200/Melting point 225 oC 

(Decomposition) 

230-250 oC 

(Decomposition) 

225-230 oC 

(Decomposition) 

240 oC 

(Decomposes)

830.7200/Boiling point Not applicable (substances are all solids)

830.7300 

Density 48 lbs/cubic ft

35 lb/cubic ft 

850 – 950 kg/cubic meter 

Specific gravity 2.05 g/ml 

at 20 o

C 

2.02 - 2.10 g/cc 62.56 lb/cubic ft. 

830.7550 

Partition coefficient 

 (n-octanol/water) 

1.28 -0.06 0.94 -0.06 

830.7840 

Solubility in water 0.8 g/100 g at 25°C 24.8 g/100g at 26.8o

C 1.2 g/100g at 25 oC 26.2 g/l00 ml at 25°C 

830.7950 

Vapor pressure Very low, impossible to measure 

1.4 Use/Usage Description 

1.4.1 Registrations 

There are 451 registered products that contain chlorinated isocyanurates. The distribution of 

products by specific isocyanurate is presented in Table 5. Most of the products are formulated as 

solid granules or tablets and a few products are formulated as liquids. 

Table 5 - Distribution of Products by Specific Chlorinated Isocyanurate 

Chemical Name PC Code Number of 

Products Percent a.i. Formulations 

Dichloro-s-triazinetrione 081401 2 0.8 to 99.7a Dust, Tablet/Pellet 

Sodium dichloro-s-triazinetrione 081404 81 10 to 99b Granules, Tablets/Pellets, Liquid, 

Impregnated Stick-On Patch 

Trichloro-s-triazinetrione 081405 246 1.9 to 100c

Granule, Tablets/Pellets, Liquid, 

Water soluble packaging, 

wettable powder 

Sodium dichloro-s-triazinetrione 

dihydrate 081407 122 1.0 to 100 

Granules, Tablets/Pellets, 

Wettable Powder, Dust, Water 

soluble packaging, Liquidsolutions and emulsifiable 

N/A: not applicable 

a

 One product also contains trichloro-s-triazinetrione as an active at a declared content of 66.96% b

 Two products also contain trichloro-s-triazinetrione as an active: one with 44.6% and one with 70.54%. 

c

 Two products also contain sodium dichloro-s-triazinetrione as an active at declared content of 18.19 and 14.5% 

and one product also contains dichloro-s-triazinetrione as an active at a declared content of 53.2%. 
Page 10 of 52

1.4.2 Summary of Registered Uses 

The chlorinated isocyanurates are registered for use as disinfectants, sanitizers, microbiocides, 

microbiostats, bacteriocides, bacteriostats, slimicides, algaecides, fungicides, fungistats, 

tuberculocides and virucides as summarized in Table 6. Application rates are provided in terms 

of the theoretical amount of available chlorine based on molecular weight ratios. For products 

that contain more than one chlorinated isocyanurate, the reported available chlorine application 

rate is expressed as the total chlorine produced from all chlorinated isocyanurates in the product. 

Table 6 – Summary of Chlorinated Isocyanurate Antimicrobial Uses 

Use Site Application Rate 

(In Terms of Available Chlorine) 

Hard Surface Disinfection and Sanitization (Many Labels) 

Agriculture/Farm Structure and Equipment 100 to 971 ppm 

Animal Housing (poultry, swine, zoos and farms) 97 to 1,300 ppm 

Commercial, Institutional, Industrial Premise and Equipment 117 to 6,846 ppm 

Dairy Farm Milk Handling Facilities and Equipment 97 to 572 ppm 

Eating Establishments (Including Utensils) 100 to 150 ppm 

Egg Handling Equipment and Washing 97 to 300 ppm, 13,000 ppm 

Food Processing Plant Premise and Equipment 

(includes dairy/cheese, poultry, meat and seafood) 101 to 4,900 ppm 

Household/Domestic Dwellings (Includes floors) 100 to 4,720 ppm 

Laundry Premises and Equipment 113 to 457 ppm 

Medical/Veterinary Premise and Equipment 100 to 937 ppm 

Mushroom Houses 102 to 644 ppm 

Laundry Sanitizer, Deodorizer, and Destainer 

Laundry (Commercial, Industrial, Institutional) 60 to 200 ppm per load 

Oil Production (Many Labels) 

Secondary Oil Recovery Injection Water 0.5 to 10 ppm 

Oil Recovery Drilling Muds and Packer Fluids 0.5 to 10 ppm 

Water Treatment (Many Labels) 

Commercial and Industrial Cooling Water Systems 

(includes once through and recirculating cooling towers) 0.5 to 10 ppm 

Drinking Water (Emergency, public and individual systems)1 0.2 - 600 ppm 

Ornamental Ponds 0.5 to 20 ppm 

Pasteurizer Water Systems 0.5 to 10 ppm 

Sewage Treatment 0.2 to 3 ppm 

Swimming Pools and SPAs2 0.5 to 8 ppm 

Waterbed Water 16 ppm 

In-Can Material Preservative (Label #935-71 Only) 

Adhesives, Water Based 71 to 2,280 ppm 

Emulsions (Vinyl Acrylic, Acrylic and PVA) 71 to 2,280 ppm 

Joint Compounds 142 to 2,280 ppm 

Paints, Interior (Vinyl Acrylic, Acrylic and PVA) 285 to 1,140 ppm 

Pigment Dispersions 142 to 2,280 ppm 

Floriculture (Labels #72992-12 and #72992-16) 

Water Conditioner for Flower Cuttings (Tablet or Label) 17 to 78 ppm 

1

 Higher rates are for emergency treatments after floods. Maintenance rate is 0.2 ppm. 

2

 Higher rates are for shock and winterizing treatments. Water cannot be entered until level is below 3 ppm. 
Page 11 of 52

Dichloro-s-triazinetrione (PC Code: 081401), sodium dichloro-s-triazinetrione (PC Code: 

081404), trichloro-s-triazinetrione (PC Code: 081405), and dichloro-s-triazinetrione dihydrate 

(PC Code: 081407) are all registered as disinfectants and sanitizers for use to control bacteria on 

indoor food and non-food contact hard surfaces and equipment at food processing plants, eating 

and food handling establishments, commercial and industrial premises, hospital and medical 

premises (human/veterinary), laboratories, zoos, livestock and animal living quarters, and indoor 

hard surfaces and contents of household/domestic dwelling premises. Additionally sodium 

dichloro-s-triazinetrione and dichloro-s-triazinetrione dihydrate are registered for use as a 

virucide on hard surfaces in hospitals (human/veterinary), institutional, and zoo premises, pet 

kennels, animal cages, zoo premises and animal enclosures and transport vehicles, animal 

feeding and water equipment, locker room premises, and shower and bathroom premises. Except 

for dichloro-s-triazinetrione, these chlorinated isocyanurates are registered for use in residential, 

commercial, and institutional laundry products. 

Dichloro-s-triazinetrione is registered for use to treat swimming pool water as an algaecide and 

bacteriocide. Sodium dichloro-s-triazinetrione, trichloro-s-triazinetrione, and dichloro-striazinetrione dihydrate, in addition to treating swimming pool water, are registered for use as 

microbiocides, microbiostats, bacteriocides, disinfectants, sanitizers, fungicides, and algaecides 

in non-food industrial water systems (air washer water systems, commercial/industrial water 

cooling systems, heat exchanger systems, cooling towers, lakes/ponds/reservoirs (without human 

or wildlife use), pasteurizer water, cannery cooling canal water, hot tub, whirl pool, and spa 

waters, ornamental ponds and lakes, aquaria water, ornamental fountains, sewage systems, waste 

water systems, sewage settling ponds, septic tanks, sewer lines (main), oil recovery drilling muds 

and packer fluids, and secondary oil recovery injection water. Additionally sodium dichloro-striazinetrione and dichloro-s-triazinetrione dihydrate are registered for use as a virucide for the 

treatment of water used in spas, immersion ultrasonic tank water, whirlpool bath water, and shoe 

baths. Sodium dichloro-s-triazinetrione, trichloro-s-triazinetrione, and dichloro-s-triazinetrione 

dihydrate are also registered for use as a virucide and bacteriocide for treatment of potable water. 

Formulation types include soluble concentrates both solid and flowable, ready-to-use (RTU) 

solutions, wettable powder, water soluble packaging, granules, water dispersible granules, 

pellets, and tablets. There is a one product containing dichloro-s-triazinetrione registered only 

for use of impregnated patches for placement on fresh cut flowers as a bactericide for slimeforming bacteria. 

The labels indicate that the chloroisocyanurates can be applied to industrial water treatment 

systems and materials being preserved using both open pour and closed systems, applied to 

swimming pools and SPAs using open pour systems, applied to various hard surfaces using 

sprayers, foamers, mops and wipes, and applied to food processing equipment and systems using 

immersion and circulate in place methods. Some labels, such as EPA Reg. Nos.1677-91 and 

66570-2, also indicate that fogging can be used for applications in dairy, beverage and food 

processing plants. 
Page 12 of 52

1.4.3 Usage Information 

According to the Kline Biocides Report for 2004/2005 (Kline, 2006), the estimated U.S. 

consumption of chloroisocyanurates for 2004 was 195 million pounds. This consumption was 

distributed among recreational water (188.5 million pounds), cooling water (5.2 million pounds) 

and household, industrial and institutional disinfectants and sanitizers (1.1 million pounds). 

1.5 Regulatory History 

The chlorinated isocyanurates were first registered in the United States in 1958 for use as 

disinfectants, sanitizers, algicides, and fungicides. Dichloro-s-triazinetrione was first registered 

in the United States in 1958; sodium dichloro-s-triazinetrione was first registered in the United 

States in 1968; trichloro-s-triazinetrione was first registered in the United States in 1959; and 

sodium dichloroisocyanurate dehydrate was initially registered as a sanitizer in the United States 

on March 17 1964. The Agency completed a reregistration eligibility decision document (RED) 

in 1992, which included a reregistration decision on all current uses except the material 

preservative uses, and all of the existing uses at that time were found to be eligible for 

registration. The post-RED data call-in (DCI) was issued in May 1993. 

1.5.1 Recent/Pending Regulatory Actions 

There are currently two pending registrations for sodium dichloro-s-triazinetrione and one 

pending registration for trichloro-s-triazinetrione. 

1.5.2 Tolerance Information 

A tolerance exemption has been established for sodium dichloroisocyanurate used as a sanitizer 

on food contact surfaces of public eating places, dairy processing equipment, and food 

processing equipment and utensils [40 CFR 180.940(a)]. Tolerance exemptions have also been 

established for trichloroisocyanuric acid and dichloroisocyanuric acid and its sodium and 

potassium salts used as sanitizers on food contact surfaces of food processing equipment and 

utensils [40 CFR 180.940(c)]. All these sanitizers must be used such that the final use 

concentration of di- and trichloroisocyanuric acid chemicals does not exceed 100 ppm 

determined as total available chlorine. The Agency intends to delete the exemption for the 

potassium salt of dichloroisocyanuric acid from 40 CFR 180.940(c) because there are no 

registered products. The Agency intends to add sodium dichloroisocyanurate dihydrate (51580-

86-0) to the exemption in 40 CFR 180.940(c). 

1.6 Incidents 

1.6.1 Human Health 

A total of approximately 6,500 human health incidents are listed in the OPP Incident System for 

the chlorinated isocyanurates for the years 1992 to the present. A summary of these incidents is 

given in Table 7. The severity of the incidents range from minor effects such transient 
Page 13 of 52

respiratory irritation represented by code HD (Human Minor) to severe effects such as injuries 

and death represented by codes HB (Human Major) and HA (Human Fatality). 

Approximately 4,900 of the incidents involved the swimming pool uses. The most severe 

incidents were caused by label misuses such as premixing the chloroisocyanurate pool products 

with small amounts of water or incompatible chemicals such as bleach. These two actions 

caused explosions and the release of chlorine gas resulting in injuries such chemical burns and 

pulmonary edema. The labels clearly state that chloroisocyanurates should be not be handled in 

this manner. Less severe incidents have occurred when people have been exposed to irritating 

“fumes” when opening containers or when products fell out of floating dispensing containers 

(i.e., floaters) causing excessive dosing of the pool. 

Approximately 680 incidents are associated with the food processing uses where 

chloroisocyanurate is used to treat beverage or milkshake machines. Two major (HB) incidents 

occurred when a person drank what he or she believed to be ice tea from an unlabeled container 

containing chloroisocyanurate sanitizer solution and when a person drank a milkshake from a 

milkshake machine that had not been properly rinsed following treatment with 

chloroisocyanurate. 

Another 750 minor (HD) incidents are associated with the toilet bowl cleaning and hard 

surface disinfection uses and 7 minor incidents are associated with the industrial uses. 

Table 7 - Incidents Reported for the Chlorinated Isocyanurates 

Product Type Number of Incidents1

HA HB HC HD HE 

Dichloroisocyanuric acid (081401) 

Food Processing 0 0 0 3 0 

Pools and Spas 0 0 0 16 3 

Miscellaneous and Unspecified 0 0 0 0 1 

Sodium dichloroisocyanurate (081404) 

Food Processing 0 0 0 1 0 

Industrial Uses – Cooling Water, Paper Mills, Material Preservation 0 0 0 3 0 

Pools and Spas 0 9 1 1014 26 

Miscellaneous and Unspecified 0 0 0 8 0 

Trichloro-isocyanuric Acid (081405) 

Toilet Bowl 0 0 0 78 0 

Industrial Uses – Cooling Water, Paper Mills, Material Preservation 0 0 0 2 1 

Pools and Spas 3 19 0 3425 49 

Miscellaneous and Unspecified2 0 0 0 19 3 

Sodium dichloro-isocyanurate hydrate (081407) 

Food Processing 0 2 0 675 2 

Hard Surface Disinfection 1 0 0 671 80 

Industrial Uses – Cooling Water, Paper Mills, Material Preservation 0 0 0 4 0 

Pools and Spas 1 4 0 402 26 

Miscellaneous and Unspecified 0 1 0 0 0 

1

 HA = Human Fatality, HB = Human Major, HC = Human Moderate, HD = Human Minor, HE = Human Unspecified 2

 Two of the HD incidents involved the misuse of an industrial product in a swimming pool. 
Page 14 of 52

1.6.2 Ecological 

No chlorinated isocyanurate ecological incidents have been reported in the Agency’s OPP 

Incident Data System (IDS). 

2 Anticipated Data Needs 

Table 8 presents a summary of the data anticipated as being needed to support this registration 

review. 
Page 15 of 52

Table 8 - Studies Anticipated as Needed for the Registration Review of the Chlorinated Isocyanurates 

OCSPP 

GLN Study Name Test Substance

Time Frame 

(Months from 

DCI Receipt)

Risk 

Assessment(s) 

Data Will Support

Use Site(s) Triggerin

Data Requirement

875.1300 Indoor Exposure, Inhalation TGAI 24 Occupational and Residential Handler All 875.1700 Product Use Information TGAI 12 All All 875.2300 Indoor Surface Residue Dissipation TGAI 24 Residential Household floors5 850.4400 Aquatic Plant Testing using Lemna sp., Tier II Degradate (isocyanuric acid) 12 Aquatic organisms All6

850.45007 

Algal Toxicity Tier II –marine diatom, freshwater diatom, green algae 

Degradate 

(isocyanuric acid) 12 Aquatic organisms All6

850.45507 Algal Toxicity Tier II - Cyanobacteria Degradate (isocyanuric acid) 12 Aquatic organisms All6835.31108 Ready Biodegradability Degradate (isocyanuric acid) 12 Aquatic exposure and risk All6835.32208 Porous Pot Test Degradate (isocyanuric acid) 12 Aquatic exposure and risk All6835.32408 

Simulation Test – Aerobic Sewage Treatment: A. Activated Sludge Units 

Degradate 

(isocyanuric acid) 12 Aquatic exposure and risk All6

835.32808 

Simulation Test to Assess the Biodegradability of Chemicals Discharged to wastewater 

Degradate 

(isocyanuric acid) 12 Aquatic exposure and risk All6

835.4300 Aerobic aquatic metabolism Degradate (isocyanuric acid) 12 Aquatic exposure and risk All6835.4400 Anaerobic aquatic metabolism Degradate (isocyanuric acid) 12 Aquatic exposure and risk All6

OECD 209 or 

850.33009 

Activated Sludge Respiration Inhibition (ASRI) 

Degradate 

(isocyanuric acid) 12 Aquatic exposure and risk All6

860.146010 Food-handling TEP 24 Dietary and aggregate risk Food processing, dairy

and public eating establishments 

Special 

Study11 Migration studies TEP 24 Dietary and aggregate risk Adhesives and pulp/paper mill slimicide use 
Page 16 of 52

1 Applicable Occupational Handler Exposure Scenarios: 1- Open pour liquids, granules and powder for hard surface disinfection and po

pour granules for material preservation; 3- Mop, wipe and trigger spray for hard surface disinfection; 4- Hand wand spray disinfection oplants; 5- Fogging disinfection of egg and food processing plants; and 6- Brush, roller and spray application of preserved paints. 

2 Applicable Residential Handler Exposure Scenarios: 1- Open pour liquids, granules and powder for pool treatment; 2- Mop, wipe and 

surface disinfection; and 3- Brush, roller and spray application of preserved paints. 

3 It may be possible to use proprietary surrogate exposure data if data compensation issues can be addressed. 4 If the labels are modified to require automatic foggers in place of hand held foggers, then the study of hand held fogging exposures woneeded. 5 If surface residue data are not available, then the standard assumption of 100 percent transferable surface residue will be used which m6 Industrial Process and Water Treatment: Cooling Tower and Swimming Pools and Water Beds; Hard Surfaces Disinfectants and Sanit

industrial; Laundry Products: DtD residential and commercial; Material Preservatives: DtD Production and In-Service. 

7 All uses footnoted with marine diatom and freshwater diatom data for material preservative uses, hard surface disinfection and sanitiz

use may be eligible for data waiver if green algae (Selenastrum capricornutum) NOAEC results are greater than or equal to 1 ppm. The 

address this. 

8 EPA has published final guidelines for four biodegradation studies. The biodegradation study anticipated to be required for chlorinated 

degradate (Cyanuric acid based on an Activated Sludge Respiration Inhibition Test. The Agency anticipates codifying these studies in 4future. 

9 The results of the Activated Sludge Respiration Inhibition Test (ASRI) expected to be required will determine which of these four bio

anticipated to be required. If the ASRI test EC50 is less than or equal to 20 mg/L, then either the (i)Biodegradation in Activated Sludge 

Test – Aerobic Sewage Treatment: A. Activated Sludge Units or (iii) the Porous Pot Test would be anticipated to be required. If the AS

than 20 mg/L, then the DCI expected to be issued would provide that the registrant would choose to conduct either: (i) Ready BiodegraBiodegradation in Activated Sludge or b) Simulation Test – Aerobic Sewage Treatment: A. Activated Sludge Units or c) the Porous PoBiodegradability study is conducted and passes, then no further testing would be expected to be required. If, however, the antimicrobiaBiodegradability study, then the a) Biodegradation in Activated Sludge or b) Simulation Test – Aerobic Sewage Treatment: A. ActivatePorous Pot study would be expected to be required. The appropriate Test Substance to satisfy the guideline requirement is the degradate 

10 Residue chemistry data are anticipated to be needed to determine dietary exposure to cyanuric acid/isocyanuric acid following sanitiz

surfaces of food processing plants (including dairies) and food-handling facilities (including public eating places). Protocol submission anticipated DCI will address this. 

11 Migration of cyanuric acid/isocyanuric acid from preserved adhesive to food and from paper/paperboard to food following the slimicDCI will provide that a protocol must be submitted for EPA approval prior to initiating the study.
Page 17 of 52

3 Human Health Risk Assessment 

The Agency anticipates the need to conduct a human health risk assessment for the chlorinated 

isocyanurates. 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 9 presents the existing toxicological points of departure (POD) for the chlorinated 

isocyanurates. The existing PODs were established by the EPA Hazard Identification 

Assessment Review Committee (HIARC) in 2001 based on the toxicity database for the 

isocyanuric acids. It should be noted that the PODs for dermal exposure are based on oral 

studies and are used with a dermal absorption factor of 1 percent to account for route to route 

extrapolation. Because the PODs for dermal exposure are the oral NOAELs of 200 mg/kg/day 

and 154 mg/kg/day and the dermal absorption is 1 percent, the dermal equivalent PODs are 

20,000 mg/kg/day and 15,400 mg/kg/day. Because these PODs are much higher than the limit 

dose of 1000 mg/kg/day for dermal toxicity studies, the dermal toxicity is very low and does not 

need to be assessed. See Appendix B for additional information. 

Table 9 – Existing Toxicology Endpoints 

Exposure 

Scenario 

DoseA

(mg/kg/day) Point of Departure (POD) Study 

Acute Dietary 

(females 13+) 

NOAEL= 200 

mg/kg/day 

UF = 100 

Increased incidence of hydrocephaly at 500 

mg/kg/day. 

Developmental 

Toxicity - Rat 

Acute RfD =2.0 mg/kg/day 

Acute Dietary 

(gen. Pop.) N/A No appropriate endpoint was identified for the general population 

Chronic Dietary NOAEL =154 

mg/kg/day 

UF = 100 

Decreased survival in male rats and lesions of the 

urinary tract and heart at the next highest dose of 

502 mg/kg/day.

Chronic Toxicity / 

Carcinogenicity- Rat 

Chronic RfD = 1.5 mg/kg/day 

Incidental Oral, 

Short-Term N/A No appropriate endpoint was identified for short-term incidental oral risk. 

Incidental Oral, 

Intermediate-term 

NOAEL = 204 

mg/kg/day 

Based upon hyperplasia of the urinary bladder at a 

dose of 672 mg/kg/day. 

90-Day Oral Toxicity 

- Rat 

Short- and 

Intermediate-Term 

(Dermal) 

NOAEL= 200 

mg/kg/dayB

UF = 100C

Increased incidence of hydrocephaly at 500 

mg/kg/day. 

Developmental 

Toxicity - Rat 

Long-Term 

(Dermal) 

NOAEL=154 

mg/kg/dayB 

UF = 100C

Decreased survival in male rats and lesions of the 

urinary tract and heart at the next highest dose of 

502 mg/kg/day.

Chronic Toxicity/ 

Carcinogenicity - Rat 
Page 18 of 52

Exposure 

Scenario 

DoseA

(mg/kg/day) Point of Departure (POD) Study 

Inhalation(Any 

time point) 

NOAEL= 

0.0032 mg/L 

UF = 100C

Based on increased incidence of clinical signs, 

decreased body weight, and increased relative lung 

weight at the next highest dose level. 

28-Day Inhalation 

Toxicity - Rat 

A The endpoints are based on toxicity studies of isocyanuric acid as discussed in the HIARC report of 1/25/2001. 

B

 Since an oral endpoint was selected for dermal risk assessments, a dermal absorption value of 1.0 percent (i.e. a 

dermal absorption factor of 0.01) should be used in route-to-route extrapolations. This value is based on available 

data as discussed in an OPP Memorandum of 20 March 1980 from Robert Zendzian, Ph. D. to James Skaptason. 

C

 The HIARC report lists uncertainty factors (UF) of 100 for occupational dermal and inhalation exposure. The 

HIARC report does not list UFs for residential exposure. 

3.2 Dietary Exposure 

The Agency anticipates the need to conduct a dietary assessment. Uses of chlorinated 

isocyanurates that may result in dietary exposures include food processing plants including 

dairies and food-handling facilities including public eating places, emergency drinking water, 

and individual and public drinking water systems including tanks, wells, reservoirs, and basins. 

Dietary risk is characterized in terms of the Population Adjusted Dose (PAD), which reflects the 

reference dose (RfD), either acute or chronic, that has been adjusted to account for the FQPA 

Safety Factor (SF). This calculation is performed for each population subgroup for which an 

endpoint exists. A risk estimate that is less than 100% of the acute or chronic PAD is not of 

concern. Acute dietary risk for PTAP will be assessed by comparing dietary exposure estimates 

expressed in mg/kg/day to the acute Population Adjusted Dose (aPAD) and chronic Population 

Adjusted Dose (cPAD). 

3.2.1 Food 

Human dietary exposure to chlorinated isocyanurate residues may occur as a result of their use to 

sanitize food contact surfaces of food processing plants including dairies and food-handling 

facilities including public eating places. After treatment, most product labels state that food 

contact surfaces should be drained and that they should not receive a potable water rinse prior to 

reuse. However, some product labels state that a potable water rinse should be made after 

treatment. This issue will be addressed during the risk assessment stage of this registration 

review. Chlorinated isocyanurates are also used to preserve adhesives and as slimicides during 

production of paper/paperboard which may be used for food-contact purposes (labels are silent 

re: whether food contact is prohibited). 

The Agency did not conduct a dietary risk assessment to support the 1992 RED for the 

Chlorinated Isocyanurates because, at that time, the uses noted above were under the purview of 

the Food and Drug Administration. Also, FQPA had not yet become law meaning that aggregate 

risk assessments were not conducted. Residue chemistry data are expected to be needed to 

determine dietary exposure to the stable degradates and tautomeric pair cyanuric acid and 

isocyanuric acid following sanitization of food contact surfaces of food processing plants 
Page 19 of 52

(including dairies) and food-handling facilities (including public eating places), adhesive 

preservation, and slimicide use in the pulp slurry to make paper/paperboard for food contact. 

The acute and chronic assessments to be conducted during registration review will estimate 

dietary exposure to chlorinated isocyanurates and the degradate cyanurate/isocyanurate for all 

population subgroups. 

3.2.2 Drinking Water 

The chlorinated isocyanurates are registered for emergency drinking water treatment as well as 

routine (non-emergency) treatment of individual and public drinking water systems including 

tanks, wells, reservoirs, and basins. While the chlorinated isocyanurate active ingredients are not 

persistent, contamination of drinking water by the degradate cyanurate/isocyanurate may occur 

as a result of discharge of waste water from paper and paperboard mills, down-the-drain from 

swimming pools or food-handling establishments, or run-off from livestock premises. 

Chlorinated isocyanurates degrade rapidly to cyanurate/isocyanurate and hypochlorous acid. 

Both parent compounds and cyanurate/isocyanurate are highly water-soluble and weakly sorbed 

to soil, sediment, and sludge. The routine water treatment use was assessed in response to a 

registrant proposal that EPA approve these uses on four of their product labels (T. McMahon, 

3/26/01, D270655). Estimated exposures were compared to the cPAD value of 1.5 mg/kg/day as 

determined by the HIARC (report dated 1/25/01). Chronic dietary risks were reported to be 2% 

of the cPAD for adults and 6% of the cPAD for children. 

The acute and chronic assessments to be conducted during registration review will estimate 

drinking water exposure to the degradate cyanurate/isocyanurate for all population subgroups. 

3.3 Occupational and Residential (ORE) Exposures 

3.3.1 ORE Exposure Assessed in the RED 

Occupational and Residential (ORE) Exposures were not assessed in the RED because “the 

chlorinated isocyanurates did not appear to induce significant acute (except eye irritation), 

subchronic or chronic toxicity based on available information”. The RED further stated that “the 

toxicity data indicate that these compounds do not meet the Agency's toxicity criteria for the 

requirement of post-application re-entry and/or mixer/loader/applicator exposure monitoring 

data. Accordingly, occupational and residential exposure data are not required to support the 

reregistration of the chlorinated isocyanurates.” 

3.3.2 ORE Exposures Assessed after the RED 

The dermal and incidental oral exposures of persons swimming in pools treated with chlorinated 

isocyanurates were assessed in D270656 of 2/26/2001 using the endpoints established by the 

HIARC. These endpoints included the intermediate term incidental oral NOAEL of 204 

mg/kg/day and the long term NOAEL of 154 mg/kg/day. These exposures were calculated for 
Page 20 of 52

both adult (77 kg) and child (29 kg) competitive swimmers using the SWIMODEL and assuming 

a chlorinated isocyanurate water concentration of 55 mg/liter, an exposure time of 3.0 hours per 

event, an event frequency of 150 events per year, a water ingestion rate of 0.05 liters per hour 

and a permeability coefficient of 1.5 x 10-5 cm/hr. The oral MOEs were 270 for adults and 240 

for children and the dermal MOEs were 720 for adults and 270 for children. The combined 

MOEs were 160 for adults and 110 for children. All these MOEs were considered to be not of 

concern because they exceeded the target MOE of 100. 

The exposures to persons swimming in public pools treated with chloroisocyanurates was also 

measured using biomonitoring of urine to determine water ingestion rates in a study conducted 

by the EPA Office of Research and Development (ORD). Approximately 550 swimmers were 

included in this study and the pilot results from 53 swimmers were reported in Dufour, 2006 and 

incorporated into the Exposure Factors Handbook (EPA, 2011). Although the purpose of this 

study was to measure water ingestion rates, the study could also be used to back calculate 

chloroisocyanurate exposures for comparison to the estimates derived from the SWIMODEL. 

3.3.3 ORE Exposures that will Need to Be Assessed for Registration Review 

Because endpoints of concern were identified after the RED for incidental oral and inhalation 

exposures, occupational and residential exposures will need to be assessed for registration 

review. Although endpoints were also selected for dermal exposure, dermal exposures will not 

need to be assessed for reasons previously discussed in Section 3.1. A listing of the exposure 

scenarios that need to be assessed is included in Table 10. 

Table 10 - Occupational Exposure Scenarios for the Chlorinated Isocyanurates 

Scenario Exposure 

Route(s) Duration 

Occupational Exposures

Open pour liquids, granules and powder for hard surface 

disinfection and pool treatment Inhalation Short and Intermediate Term 

Open pour granules for material preservation Inhalation Short and Intermediate Term 

Mop, wipe and trigger spray application for disinfection 

(Medical and CII premise and equipment) Inhalation Short and Intermediate Term 

Hand wand spray application for disinfection 

(animal housing, food processing plants) Inhalation Short and Intermediate Term 

Fog application for disinfection 

(egg and food processing plants) Inhalation Short and Intermediate Term 

Brush, Roller and Spray Application of Preserved Paint Inhalation Short and Intermediate Term 

Residential Exposures

Mop, wipe and trigger spray application for disinfection 

(Household/domestic dwellings, includes floors) Inhalation Short and Intermediate Term 

Open pour liquids, granules and powder for pool treatment Inhalation Short Term 

Brush and Roller Application of Preserved Paint Inhalation Short Term 

Swimming in Treated Pools Incidental oral Short and Intermediate Term

Ingestion of treated drinking water Oral Long Term 

Toddlers playing on disinfected floors Incidental Oral Short and Intermediate Term
Page 21 of 52

3.4 Aggregate and Cumulative Exposure 

3.4.1 Aggregate Exposures 

Upon a reevaluation and selection of toxicological endpoints, combined with the human health 

exposure assessments expected as a part of this registration review case, aggregate exposures 

will need to be assessed. This assessment will likely include dietary exposures and residential 

exposures. 

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 the chlorinated isocyanurates and any other 

substances and the chlorinated isocyanurates do not appear to produce a toxic metabolite 

produced by other substances. For the purposes of this registration review, therefore, EPA has 

not assumed that the chlorinated isocyanurates have 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 the 

policy statements released by EPA’s Office of Pesticide Programs at 

http://www.epa.gov/pesticides/cumulative/. 

4 Environmental Risk Assessment 

The Agency has not conducted a risk assessment that supports a complete endangered species 

determination for the chlorinated isocyanurates. The ecological risk assessment planned during 

registration review will allow the Agency to determine whether the use of chlorinated 

isocyanurates has 'no effect' or 'may affect' federally listed threatened or endangered species 

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

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

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

Services), as appropriate. 

4.1 Environmental Conceptual Model Exposure Pathways 

Based on the chemical/physical properties and environmental fate studies (Appendix A) and the 

uses in Table 6, the Agency has developed conceptual models for the environmental exposure to 

the chlorinated isocyanurates and their major metabolites/degradates. For all uses, the Agency 

assumes that environmental exposures may occur, especially from the cyanuric/isocyanuric acid 

metabolites, but bioconcentration will not be significant because of their low log Kow (log P) 

and high water solubility values. This environmental exposure is expected to be of shorter 

duration in the presence of acclimated microorganisms or anaerobic conditions, based on 

literature references (Zeyer et al., 1980, Ernst and Rehm, 1990, Jessee et al., 1983, Cook et al., 

1985, Saldick et al., 1974). The ultimate breakdown products of cyanuric acid are carbon 

dioxide (CO2) and ammonia (NH3), both of which can be released into air or incorporated into 
Page 22 of 52

microbial biomass. Figure 1 below contains the conceptual model for the use of disinfection and 

sanitizing products including cleaning products for floors and laundry additives (e.g., pre-wash 

cycle sanitizers, cleansers) which go down the drain after use. Figure 2 below contains the 

conceptual model for swimming pools and waterbed water uses. Figure 3 contains the 

conceptual model for cooling towers. Figure 4 contains the conceptual model for in-can 

preservatives. 

The use of chlorinated isocyanurates in industrial processes and water systems has a potential to 

expose aquatic organisms to hypochlorous acid and cyanuric/isocyanuric acid. However, 

hypochlorous acid has a finding of “no effect” for cooling towers and water process system uses 

and therefore is not of concern for chlorinated isocyanurates2

. The risk assessment to be 

conducted as part of this registration review will evaluate risk from the chlorinated isocyanuric 

acid metabolite, isocyanuric acid. 

Figure 1 Conceptual Model for Ecological Exposure and Effects of Chlorinated 

Isocyanurates and their Reaction Products/Degradates from Sanitizing and Disinfecting 

Uses for Laundry and Hard Surfaces to Aquatic and Terrestrial Organisms 

 

2

 Na & Ca Hypochlorite Registration Review: Final Work Plan, Docket ID EPA-HQ-OPP-2012-0004-0006 

Stressor

Source

Receptors

and Exposure

Routes

Attribute

Change(s)

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in algae

Reduction in prey

Modification of PCEs

related to prey availability

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Modification of PCEs related to

habitat

Surface Water/Sediment

Aquatic Animals

Invertebrates

Vertebrates

Exposure

Media

Ingestion Ingestion

Uptake/gills

or integument

Aquatic Plants

Non‐vascular

Vascular

Uptake or sorption/cell,

roots, leaves,

Piscivorous*

Invertebrates

Vertebrates

Phytoplanktivore/

Herbivore

Invertebrates

Vertebrates

*As used here this term refers to animals (terrestrial or aquatic) that eat not just fish but any aquatic animal (e.g., amphibians, mollusks, crustaceans, etc.)

Ingestion

Waste Water Treatment Plant (WWTP)

Key

Most likely

exposure pathway

contributing to risk

Low likelihood of

contributing to risk

Disinfection and Sanitizing Products: cleaning products for floors  and

laundry additives (e.g., pre‐wash cycle sanitizers, cleansers)

WWTP

microorganisms

Uptake or

sorption

Population

Respiration

inhibition

Down‐the‐drain disposal
Page 23 of 52

Figure 2 Conceptual Model for Ecological Exposure and Effects of Chlorinated 

Isocyanurates and their Reaction Products/Degradates from Swimming Pool and Water 

Bed Uses to Aquatic and Terrestrial Organisms 

Stressor

Source

Receptors

and Exposure

Routes

Attribute

Change(s)

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in algae

Reduction in prey

Modification of PCEs

related to prey availability

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Modification of PCEs related to

habitat

Surface Water/Sediment

Aquatic Animals

Invertebrates

Vertebrates

Exposure

Media

Ingestion Ingestion

Uptake/gills

or integument

Aquatic Plants

Non‐vascular

Vascular

Uptake or sorption/cell,

roots, leaves,

Piscivorous*

Invertebrates

Vertebrates

Phytoplanktivore/

Herbivore

Invertebrates

Vertebrates

*As used here this term refers to animals (terrestrial or aquatic) that eat not just fish but any aquatic animal (e.g., amphibians, mollusks, crustaceans, etc.)

Ingestion

Waste Water Treatment Plant (WWTP)

Key

Most likely

exposure pathway

contributing to risk

Low likelihood of

contributing to risk

Pool Treatment and Waterbed Use

WWTP

microorganisms

Uptake or

sorption

Populatio

n

Respiratio

n

inhibition

Stormwater drain disposal Disposal to sanitary drain system
Page 24 of 52

Figure 3 Conceptual Model for Ecological Exposure and Effects of Chlorinated 

Isocyanurates and their Reaction/Degradates from Cooling Water Tower Uses to Aquatic 

and Terrestrial Organisms 

 

Stressor

Source

Receptors

and Exposure

Routes

Attribute

Change(s)

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in algae

Reduction in prey

Modification of PCEs related

to prey availability

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Modification of PCEs related to

habitat

Surface Water/Sediment

Aquatic Animals

Invertebrates

Vertebrates

Exposure

Media

Ingestion Ingestion

Uptake/gills

or integument

Aquatic Plants

Non‐vascular

Vascular

Uptake or sorption/cell, roots,

leaves,

Piscivorous*

Invertebrates

Vertebrates

Phytoplanktivore/

Herbivore

Invertebrates

Vertebrates

*As used here this term refers to animals(terrestrial or aquatic) that eat not just fish but any aquatic animal (e.g., amphibians, mollusks, crustaceans, etc.)

Ingestion

Waste Water Treatment Plant (WWTP)

Key

Most likely

exposure pathway

contributing to risk

Low likelihood of

contributing to risk

Cooling Tower (Once Through and Recirculating)

WWTP

microorganisms

Uptake or

sorption

Population

Respiration

inhibition

Direct Discharge
Page 25 of 52

Figure 4 Conceptual Model for Ecological Exposure and Effects of Chlorinated 

Isocyanurates and their Reaction/Degradates from the Use and Disposal of In-Can or InContainer Material Preservatives to Aquatic Organisms 

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 obtained from ECOTOX will be used to evaluate the potential direct and 

indirect effects of the chlorinated isocyanurates and their degradates to aquatic and terrestrial 

receptors. Data discussed herein are from registrant-submitted data and from the EPA Office of 

Water’s Ambient Water Quality Criteria for Chlorine - 1984 (EPA 1985). 

4.2.1 Mechanism of Action 

In the aquatic environment, toxic action of chlorinated isocyanurates is largely due to the 

formation of hypochlorous acid when chlorine reacts with water. Adverse effects of 

hypochlorous acid are due mainly to its corrosive action. Acute necrosis may occur. Fish gillsStressor

Source

Receptors

and Exposure

Routes

Attribute

Change(s)

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in algae

Reduction in prey

Modification of PCEs related

to prey availability

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Modification of PCEs related to

habitat

Aquatic Animals

Invertebrates

Vertebrates

Exposure

Media

Ingestion Ingestion

Uptake/gills

or integument

Aquatic Plants

Non‐vascular

Vascular

Uptake or sorption by

cells, roots, leaves,

Piscivorous*

Invertebrates

Vertebrates

Phytoplanktivore/

Herbivore

Invertebrates

Vertebrates

*As used here this term refers to animals(terrestrial or aquatic) that eat not just fish but any aquatic animal (e.g., amphibians, mollusks, crustaceans, etc.)

Ingestion

Waste Water Treatment Plant (WWTP)

Key

Most likely

exposure pathway

contributing to risk

Low likelihood of

contributing to risk

In‐Surface Use of In‐Can or In‐Container Material Preservatives

WWTP

microorganisms

Uptake or

sorption

Population

Respiration

inhibition

Down‐the‐drain disposal of waste water from

paint roller, brush, and tray rinsate

Surface Water/ Sediment

Leaching from Exterior Facades

and Structures to Storm Drains
Page 26 of 52

structure may be damaged; gill necrosis can lead to respiratory problems and asphyxiation. The 

protective slime coating on fish also may be removed due to corrosive action. 

4.2.2 Measures of Effect (Ecotoxicology Endpoints)

Current selected ecotoxicological endpoints for conducting the risk assessment are provided in 

Table 11. All available ecotoxicity endpoints from studies submitted by registrants are tabulated 

separately for each isocyanurate in Appendix C. Available information on water quality criteria 

for chlorine residual is also discussed in Appendix C. The Ambient Water Quality criteria for 

Chlorine – 1984 document contains a review of public literature on effects of chlorine (total 

residual chlorine (TRC) for freshwater species and chlorine produced oxidants (CPO) for 

estuarine/marine species) and derives freshwater and saltwater organism acute and chronic water 

quality criteria. Current ambient water quality criteria (EPA, 2012) for chlorine are based on the 

1986 Water Quality Document (EPA, 1986) which contained slight data updates to the 1984 

document.OPP uses the most sensitive toxicity values for assessing risk to each receptor group. 

The endpoints that are expected to be used for the chlorinated isocyanurates ecological risk 

assessment are presented in Table 11. Data gaps also are indicated. No effects data on 

cyanurate/isocyanuric acid have been submitted to the OPP for review in support of pesticide 

registration. The Agency recognizes that isocyanuric acid is an EPA high production volume3

(HPV) chemical for which a Screening Information Data Set (SIDS) Assessment Report was 

performed (OECD SIDS 1999 and IIHAC 2003). Values found in these sources have been listed 

in Appendix C and consist of freshwater fish and invertebrate and green algae data. While some 

critical elements of these studies are identified in the HPV SIDS files, there is insufficient 

information available on the studies for AD to review the studies for purposes of a risk 

assessment. ECOSAR v1.1 was used to estimate freshwater and estuarine/marine fish and 

invertebrate acute and chronic values and the median effect concentration (EC50) and maximum 

allowable toxicant concentration (MATC; geometric mean of the NOAEC and LOAEC) for 

green algae. 

Table 11 – Existing Ecological Effects Endpoints 

Receptor 

Group 

Test 

Materiala Surrogate 

Species 

Risk 

Scenario Toxicity Endpoint Reference 

Freshwater fish 

TRC Rainbow trout Acute 96-h LC50 = 80 μg ai/L MRID 00150966

Chronic AWQ criteria = 11 ug/l EPA 2012b

isocyanuric 

acid 

Generic Acute 96-h LC50 = 72.0 mg/L ECOSAR v 1.1 

Rainbow trout Chronic MATC = 1.85 mg/L ECOSAR v1.1 

Freshwater 

invertebrates 

TRC Waterflea Acute 48-h EC50 = 110 μg/L MRID 255593 

Chronic AWQ criteria = 11 ug/L EPA 2012b

isocyanuric 

acid Waterflea Acute 48-h EC50 = 34.65 mg/L ECOSAR v1.1 

Chronic NOEC = 1.49 mg/L ECOSAR v 1.1 

Estuarine/marine 

fish 

CPO Atlantic 

silverside 

Acute LC50 = 37 μg/L EPA 1985 

Chronic AWQ criteria = 7.5 ug/L EPA 2012b

Isocyanuric Generic fish Acute 96-h LC50 = 46.9 mg/L ECOSAR v1.1 

 

3

 http://www.epa.gov/hpv/pubs/general/hpvchemdata.htm 
Page 27 of 52

Receptor 

Group 

Test 

Materiala Surrogate 

Species 

Risk 

Scenario Toxicity Endpoint Reference 

acid Chronic MATC = 2.46 mg/L ECOSAR v1.1 

Estuarine/marine 

invertebrates 

CPO Eastern oyster Acute EC50 = 26 μg/L EPA 1985 

Chronic AWQ criteria = 7.5 ug/Lc EPA 2012b

Isocyanuric 

acid Mysid Acute 96-h LC50 = 6.97 mg/L ECOSAR v1.1 

Chronic MATC = 4.82 mg/L ECOSAR v1.1 

Algae 

TRC 4 spp. EC50 Not required 

NOAEL Not required 

isocyanuric 

acid Green algae EC50 96-h EC50 = 0.114 mg/Lb

 ECOSAR v1.1 

NOAEL MATC = 0.057 mg/Lb ECOSAR v1.1 

Aquatic vascular 

plants 

TRC 

Lemna 

EC50 Not required NOAEL 

Isocyanuric 

acid 

EC50 Data required NOAEL 

Birds Trichloro-striazinetrione Mallard Acute LD50 = 1021 mg ai/kg-bw MRID 00126521

Chronic Not required 

Mammals 

Chlorinated 

isocyanurates Lab. rat Acute LD50 = 787 mg/kg-bw MRID 00150959

Chronic >1000 mg/kg-bw/day See Section 4.1.3

isocyanuric 

acid Lab. rat Acute LD50 = 7700 mg/kg-bw OECD SIDS 1999

Nontarget insects Isocyanuric 

acid Honey bee Acute Not required 

a

 TRC (total residual chlorine) refers to the sum of free chlorine and combined chlorine in fresh water; in saltwater, 

in which chlorine forms will react with bromide, CPO (chlorine-produced oxidants) refers to the sum of the 

oxidative products. 

b

 Office of Water Aquatic Water Criteria value 

(http://water.epa.gov/scitech/swguidance/standards/handbook/index.cfm ) 

4.3 Exposure Analysis Plan 

4.3.1 Aquatic and Terrestrial Wildlife Exposure Estimates 

In order to address the risk hypothesis, the potential for adverse effects on the environment will 

be estimated. For down-the-drain (DtD) risk estimates, an approach that estimates the number of 

days a concentration-of-concern (COC) is exceeded, also referred to as a probabilistic dilution 

model (PDM) approach, is used to assess risk to aquatic organisms. The environmental fate and 

effects data anticipated to be needed to conduct a more refined DtD assessment are provided as 

part of the work plan. 

This analysis plan will be revisited and may be revised depending upon a full review of the data 

available in the open literature and the information submitted by the public in response to the 

opening of the Registration Review docket. 

4.3.2 Down-the-Drain Analysis 

Data received in response to the data call-in expected to be issued as part of this registration 

review will allow the Agency to estimate potential down-the-drain exposure. 
Page 28 of 52

4.4 Effects Analysis Plan 

Additional open literature studies will be identified through EPA’s ECOTOXicology (ECOTOX) 

database4, which employs a literature search engine for locating chemical toxicity data for 

aquatic life, terrestrial plants, and wildlife. The ECOTOX database will be searched when the 

risk assessment for chlorinated isocyanurates is prepared. At that time, open literature studies 

will be reviewed that potentially provide data for missing or modeled endpoint values or provide 

a value more sensitive than what is available in-house. 

Data from an ECOTOX run for chlorinated isocyanurates and their degradates will be evaluated 

for possible quantitative and/or qualitative inclusion in the risk assessment in support of 

Registration Review. Data are obtained from registrant-submitted studies or from literature 

studies identified by ECOTOX. The ECOTOX database provides more ecological effects data in 

an attempt to bridge existing data gaps and uncertainties. ECOTOX is a source for locating 

single chemical toxicity data and potential chemical mixture toxicity data for aquatic life, 

terrestrial plants, and wildlife. ECOTOX was created and is maintained by the USEPA, Office of 

Research and Development, and the National Health and Environmental Effects Research 

Laboratory's Mid-Continent Ecology Division. 

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 a 2001, registration action for chlorinated isocyanurates, 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), 

chlorinated isocyanurates are 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 

 

4

 http://cfpub.epa.gov/ecotox/ 
Page 29 of 52

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. The chlorinated 

isocyanurates are not among the 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 the 

chlorinated isocyanurates. 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 Chlorinated Isocyanurates 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 

Pesticidal use of chlorinated isocyanurates and its degradate cyanuric acid are not identified as a 

cause of impairment for any water bodies listed as impaired under section 303(d) of the Clean 

Water Act, based on information provided at the Agency’s National Pesticides Cause of 

Impairment of Waters website (searched November 27, 2012)5

. In addition, no Total Maximum 

Daily Loads (TMDL) have been developed for chlorinated isocyanurates and its degradate 

cyanuric acid, based on information provided at the Agency’s National Pesticide TMDL web site 

 

5

 http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885 
Page 30 of 52

(searched November 27, 2012)6

. More information on impaired water bodies and TMDLs can be 

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

for this pesticide. To the extent possible, data should conform to the quality standards in 

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

Other Water Quality Data in OPP’s Registration Review Risk Assessment and Management 

Process7

, in order to ensure they can be used quantitatively or qualitatively in pesticide risk 

assessments. 

TMDL Pollutant, Chlorine: Chlorine, the degradation product of chlorinated isocyanurates, is 

identified as a cause of impairment, as defined under section 303(d) of the Clean Water Act, for 

335 water bodies based on information provided at 

http://iaspub.epa.gov/tmdl_waters10/attains_impaired_waters.tmdls?p_pollutant_id=chlorine. 

Impaired Waters, Cause of Impairment: Chlorine: Chlorine is identified as a cause of 

impairment, as defined under section 303(d) of the Clean Water Act for 129 water bodies, based 

on information provided at 

http://ofmpub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail?p_cause_group_name=CH

LORINE 

Impaired Waters, Cause of Impairment: Organochlorine pesticides: Organochlorine pesticides 

are identified as a cause of impairment, as defined under section 303(d) of the Clean Water Act 

for 3 water bodies, based on information provided at 

http://ofmpub.epa.gov/tmdl_waters10/attains_impaired_waters.control?p_cause_name=organoch

lorine pesticides 

Impaired Waters, Cause of Impairment: Chlorinated pesticides: Chlorinated pesticides are 

identified as a cause of impairment, as defined under section 303(d) of the Clean Water Act for 1 

water body, based on information provided at 

http://ofmpub.epa.gov/tmdl_waters10/attains_impaired_waters.control?p_cause_name=chlorinat

ed pesticides 

During registration review of chlorinated isocyanurates, the Agency will attempt to determine 

the contribution of chlorinated isocyanurates used in swimming pools, cooling towers, hard 

surface disinfectants, and in-can/in-container preservatives to chlorine in impaired water bodies. 

The Agency will determine whether pesticide use was a contributor and/or determine if use 

might occur in these watersheds. 

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, 

 

6

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

group_name=PESTICIDES 

7

 http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1-sop.pdf 
Page 31 of 52

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

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 chlorinated isocyanurates 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. 
Page 32 of 52

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

Chlorinated Isocyanurates 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 data fulfills the data requirement would be at the sole discretion of the Agency. Presubmission 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 February 2013 the Agency will review and respond to 

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

Isocyanurates Case. 

8 References 

Ellis DD et al; Arch Environ Contam Toxicol 11: 373 - 82 (1982) 

Environmental Protection Agency. High Production Volume Information System (HPVIS). 

http://www.epa.gov/hpvis/ 

Soto, AM et al: The E-Screen Assay as a Tool to Identify Estrogen - An Update on Estrogenic 

Environmental Pollutants, Environmental Health Perspectives, Vol. 103, Supplement 7, 

pp 113-122, October 1995. 
Page 33 of 52

USEPA. 1985. Ambient Water Quality Criteria for Chlorine - 1984. Office of Water 

Regulations and Standards Criteria and Standards Division, EPA 440/5-84-030. 

USEPA. 1992. Registration Eligibility Document (RED): Chlorinated Isocyanurates. 

USEPA/Pesticides and Toxic Substances (H-7508W), September, 1992. 

Yamasaki et al; Immature Rat Uterotrophic Assay of 18 Chemicals and Hershberger Assay of 30 

Chemicals. Toxicology 183, pp 93-115, 2003. 
Page 34 of 52

Appendix A: Environmental Fate 

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

from submitted OCSPP 835 laboratory studies, the EPI-WEB 4.0 program, 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 ). These data 

sources indicate that the parent compounds trichloro- and dichloro isocyanurates readily 

dechlorinate in water to form the active ingredient hypochlorous acid and the degradates 

cyanuric/isocyanuric acid (symmetrical triazine ring tautomers with readily-interchangeable keto 

or enol groups depending on pH). Cyanuric and isocyanuric acids are highly water soluble, 

weakly sorbed, and will be in the water phase in both soil and waste water treatment plants 

(WWTPs). Cyanuric/isocyanuric acids degradates do not degrade under abiotic conditions 

(presence of water and/or light without microorganisms). However, cyanuric/isocyanuric acid is 

generally more degradable under anaerobic conditions in the presence of microorganisms 

(acclimated or unacclimated) or when acclimated microorganisms are present under aerobic 

conditions. The ultimate breakdown products of cyanuric acid are CO2 and NH3, both of which 

can be released into air or incorporated into microbial biomass. The environmental fate 

properties of trichloro isocyanuric acid and its metabolites are summarized in Table 12. 

Cyanuric/Isocyanuric Acids

Trichloro isocyanuric acid and triazine herbicides share a symmetric triazine ring. However, 

trichloro isocyanuric acid is not to be confused with agronomic herbicides that are classified as striazine compounds which have alkyl side chains, and therefore, it is not considered as part of the 

triazine cumulative assessment (See Section 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. Trichloro isocyanuric acid dechlorinates to form the cyanuric acid and isocyanuric 

acid metabolites. These metabolites, which are tautomers, are the compounds of potential 

concern based on the environmental fate data based on their environmental persistence. Under 

anaerobic conditions (acclimated or unacclimated microorganisms) and also aerobic conditions 

with acclimated microorganisms, these metabolites can be further degraded into CO2 and NH3, 

both of which can be released into air or incorporated into microbial biomass. 

Chlorinated isocyanurates (parent compounds) are used in water treatment to form 

hypochlorous acid (an oxidizing agent) when dissolved in water. Hypochlorous acid is a 

weak acid because it has a pKa (dissociation constant) of 3.7 x 10-8) at 25 oC. 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 
Page 35 of 52

microbial enzyme systems. All 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 

cyanuric/isocyanuric acid if additional free hypochlorous acid is added. 

The chlorinated isocyanurate 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 ). 

Hu (1982) found that cyanuric/isocyanuric acid is not prone to abiotic degradation (hydrolysis or 

direct photolysis in water). Microbial degradation of cyanuric/isocyanuric acid was variable and 

depended on the level of oxygenation and the presence of acclimated microorganisms. 

Cyanuric/isocyanuric acid degrades more quickly under anaerobic conditions than under aerobic 

conditions. Degradation under aerobic conditions, however, is accelerated in the presence of 

acclimated microorganisms. 

There are data available on the metabolism of the triazine ring from studies conducted with 

trichloro isocyanuric acid and from studies with the s-triazine herbicide atrazine, which like 

cyanuric/isocyanuric acid, contains a symmetric triazine ring. Mineralized cyanuric/isocyanuric 

acid forms CO2 and NH3 which can enter the air or microbial biomass (Saldick, 1974; Ernst and 

Rehm, 1990; Jessee et al., 1983; Cook et al., 1985; Zeyer et al., 1980). In artificial and natural 

wetlands and in river water draining atrazine-treated corn fields, degradation of atrazine occurred 

by acclimated microorganisms (Anderson et al., 2002). Most atrazine (60-81 %) was ultimately 

degraded (mineralized) to CO2 and NH3. The remaining applied atrazine was present in the form 

of cyanuric acid. However, in a Cedar Bog wetland with no previous exposure of 

microorganisms to atrazine, very limited atrazine mineralization was observed. In a laboratory 

biodegradation study (Kontchou and Gschwind, 1999), most s-triazine herbicides were readily 

metabolized to cyanuric acid, which did not readily degrade. These results indicate that the 

microorganisms in this study were not acclimated to cyanuric acid. Therefore, if atrazine 

mineralizes in a stream with acclimated microorganisms, then cyanuric acid would also be 

expected to mineralize because they both share a symmetric triazine ring.

Bioconcentration of the cyanuric/isocyanic acid metabolites in mammals, fish, or non-target 

aquatic organisms is not expected to be significant. This conclusion is based on the relatively 

low Log Kow (1.95), which is less than the level of concern (3.0). Also, these metabolites have 

a water solubility of approximately 2,000 mg/l (ppm) [EPI-WEB 4.0]. 

There are some outstanding environmental fate data requirements for the degradate 

cyanuric/isocyanuric acid to support Registration Review, and the anticipated need for these data 
Page 36 of 52

is based on the unknown relevance of the WWTP degradation results in the HPV document. The 

Agency expects to require the registrant to submit these studies on the fate of trichloro- and 

dichloro- cyanuric acid degradates on sewage treatment to satisfy the relevant data requirements 

listed below in Section 5.1.2 below. They can be submitted to OPP for review to meet the data 

requirements. 

Trichloro- and di-chloro- isocyanuric acids (parent compounds) degrade rapidly by hydrolysis to 

form cyanuric and isocyanuric acids (CAS 108-80-5), which are stable in the absence of 

microorganisms and under most aerobic conditions in the presence of microorganisms. Because 

of this rapid hydrolysis to cyanuric acid, photodegradation of parent compounds in water (a 

competing environmental dissipation route) is not a significant route of degradation. The 

Agency's in-house database does not have any acceptable environmental fate and transport data 

on cyanuric acid. These data are anticipated to be required to assess environmental fate for the 

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

subsequently be discharged to aquatic environments. An examination of the chemical structure, 

open literature from Science Direct (Anderson, 2002; Kontchou and Gschwind, 1999, Table 12), 

and a review of information in a Robust Summary in the HPV documentation 

(http://www.epa.gov/hpv/pubs/summaries/tricltrz/c14659rs.pdf, Table 12) indicates that a high 

percentage (up to 100 %) of cyanuric acid may be removed either by aerobic WWTPs using 

acclimated microorganisms or WWTPs using anaerobic conditions (acclimated or unacclimated 

microorganisms). The primary removal mechanism was attributed to mineralization because (1) 

there was no evidence of sorption to sludge based on the low log Kow (1.95) and water solubility 

(2,000 mg/l) and (2) the study authors reported the release of CO2 and NH3 or the incorporation 

of these substances into microbial biomass. 

To be able to give merit to this claim of mineralization, the Agency would need to review and 

evaluate the primary references cited in the HPV documentation. Without reviewing and 

evaluating these primary references and reaching the same conclusions as those presented, the 

Agency anticipates needing environmental fate data from tests including the studies listed below. 

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

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

o Activated Sludge Respiration Inhibition (ASRI, OECD 209) or Modified ASRI 

test (850.3300) 

o Ready biodegradability (GLN 835.3110), or Porous Pot Test (GLN 835.3220), or 
Page 37 of 52

Simulation Tests to Assess the Biodegradability of Chemicals Discharged to 

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

A. Activated Sludge Units (GLN 835.3240) for cyanuric acid8

. 

Table 12 Environmental Fate Data for Chlorinated Isocyanurates (di- and tri-chloro) 

Test 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 stable

pp. 10-12 of HPV 

document1

Photodegradation 

in Water 

(835.2240) 

Monosodium 

cyanurate 

Rapid degradation to cyanuric 

acid from hydrolysis (no 

photodegradation)_ 

Hu, 19822

MRID 00056479 

Cyanuric acid was stable

pp. 10-12 of HPV 

document1

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 

CO2 and NH3 

p. 15 of HPV document 

Unknown Cyanuric acid Aerobic conditions 

30 and 15 % degradation of 

cyanuric acid in 48 h for 

Pseudomonas sp. And 

Achromobacter sp. 

Ernst and Rehm. 

19905

Cyanuric acid formed 

CO2 and NH3 

pp. 17-18 of HPV 

document 

Bacteria isolated from 

corn field 

 

8

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

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

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

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

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

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

study is required. 
Page 38 of 52

Test Guideline 

(Number) 

Test Substance Result Reference Comment 

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 

from acclimated bottom 

sediment downstream of 

WWTP in Illinois that 

treats wastewater from 

trichloro isocyanuric 

acid manufacturing 

facility 

Cyanuric acid formed 

CO2 and NH3 

pp. 19-20 of HPV 

document 

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 B12227 and B-12228 and 

Klebsiella pneumoniae 

Cyanuric acid formed 

CO2 and NH3 

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 

CO2 and NH3 

pp. 22-23 of HPV 

document 
Page 39 of 52

Test Guideline 

(Number) 

Test Substance Result Reference Comment 

Unknown Cyanuric acid 100 % degradation in unknown 

time 

Sisodia et al., 

19969

Degradation of cyanuric 

acid occurs in absence of 

nitrogen when triazineacclimated bacteria are 

present 

Cyanuric acid formed 

CO2 and NH3 

pp. 24-25 of HPV 

document 

Unknown Cyanuric acid BOD5 and COD of 6.5 and 11 

mg/l 

Unknown 

reference, possibly 

Zeyer et al., 19804

p. 15 of HPV document 

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 acid totally 

mineralized in the river 

and constructed wetland 

that contained 

microorganisms that are 

acclimated to 

degradation of triazine 

rings from herbicides. 

Atrazine did not 

mineralize in wetland 

without acclimated 

microorganisms. 

Atrazine formed CO2

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 

microorganisms in 

laboratory test. 

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

2. Hu, H.C.; “Photodegradation Study of Aqueous Sodium Salt Solutions of 2,4,6-Trihydroxy -1,3,5-Triazine; 

Unpublished Study Conducted by Center Analytical Services, Princeton Chemical Research & Development Center, 

Princeton, NJ 08540 for the Isocyanurate Industry Ad Hoc Committee (EPA Consortium 55643); Study No. (none), 

January 21, 1981. MRID 00056479. 

3. 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, J. Zeyer, R. Hütter, and P. 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, 265-275 (1951). 

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, Appl. and Environ. Microbiol., 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: J. Water Pollution Control Fed., 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; Biodegradability of organic chemicals isolated from rivers. (1963) Proc. 18th 

Ind. Waste Conf. Purdue Univ. 115:278-282. 
Page 40 of 52

9 Continuous Culture Biodegradation of Simazine’s Chemical Oxidation Products, S. Sisodia, A. Weber, and J. Jensen, 

Water Research, 1996, 30(9) 2055-2064. Method: S-triazine biodegradation 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 43 (1999): 47-56. 

Hypochlorous Acid

Chlorinated isocyanurates (parent compounds) are used in water treatment to form 

hypochlorous acid (HClO), an oxidizing agent. When dissolved in water the chlorinated 

isocyanurates rapidly hydrolyze to release free chlorine and a complex series of equilibria of 

chlorinated and non-chlorinated isocyanurates. The concentration of each entity depends on the 

concentration of total available chlorine (free available chlorine plus “reservoir” or bound 

chlorine), total isocyanurate concentration, and pH. It is HClO which is the active disinfection 

moiety for all hypochlorites in aqueous medium and is the most effective form of what is called 

free chlorine residual, which is chlorine available to kill microorganisms. The trichloro form has 

three chlorine molecules which can be released, and the dichloro has two. 

HClO is a weak acid and depending upon pH can further breakdown or disassociate into a proton 

or hydrogen ion and a hypochlorite ion (ClO-

), the reaction is reversible. 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. 

HClO

ு௬௣௢௖௛௟௢௥௢௨௦ ௔௖௜ௗ

 

ርۛۛሮ H൅

ு௬ௗ௥௢௚௘௡ ௜௢௡

൅ ClO‐

ு௬௣௢௖௛௟௢௥௜௧௘ ௜௢௡

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

9

 = 7.7). 

Hence at any given time, the concentration of HClO is not very high; however, as 

it gets used up—more HClO is formed and so on. It also means that at pH 7.7, the 

ratio of HClO to ClO-

 is 50:50, while at pH 7.2, 70% is HClO and 30% is ClO-. 

o 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 ClO-

 from pH 4 to 11 as shown in 

the table below. In dilute aqueous solutions these reactions occurs in seconds or 

even in less time. This is typical of inorganic reactions. 

pH Percent HClO Percent ClO4.0 100

6.3 95 5

7.2 70 30

7.7 50 50

8.0 21 79

11 100

 

9

 pKa = -log10Ka
Page 41 of 52

o 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. 

 It is ClO- and/or HClO moieties that are the active antimicrobial portion of the 

chlorinated isocyanurates. 

 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). 

o 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௘௥

 

ሱۛሮ HClO

ு௬௣௢௖௛௟௢௥௢௨௦ ௔௖௜ௗ

൅ H൅

ு௬ௗ௥௢௚௘௡ ௜௢௡

൅ Cl‐

஼௛௟௢௥௜ௗ௘ ௜௢௡

o Elemental Cl2 oxidizing potential: one mole of elemental chlorine is capable of 

reacting with two electrons to from 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‐

஼௛௟௢௥௜ௗ௘ ௜௢௡

o 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௘௥

o The free available chlorine as a percent by weight for each of the chlorinated 

isocyanurates in this registration review is theoretically: 

Chemical Name Dichloro-s-triazinetrione Sodium dichloro-striazinetrione Trichloro-s-triazinetrione Sodium dichloro-s-triazinetrione 

dihydrate 

Available 

Chlorine (%) 70 63 90 56 

 Chlorine in addition to providing disinfection or oxidation of microorganisms can be 

consumed by 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, ClO3

-

 may be present, but the determination of exact amounts of these 
Page 42 of 52

moieties cannot be calculated as these will depend on the environmental conditions like 

pH of the medium, temperature, ionic strength, etc. 
Page 43 of 52

Appendix B: Toxicology Profile 

Hazard/Toxicity 

The most recent review of the toxicity data for the chlorinated isocyanurates was included in the 

HIARC report of January 25, 2001. This report also re-affirmed the conclusion from the RED 

that toxicology data on isocyanuric acid would support assessment of hazard from exposure to 

the chlorinated derivatives. In RED, which was written in 1992, the Agency stated that for 

purposes of hazard assessment, the isocyanurates could be divided into three groups for acute 

toxicity testing (isocyanuric acid, dichloroisocyanurates, and trichloroisocyanurates), while for 

subchronic, chronic, developmental, mutagenicity, and metabolism testing, the Agency 

determined that isocyanuric acid could represent all of the chlorinated isocyanurates. The 

Agency justified this approach at that time, stating that “since the chronic effects of chlorine for 

humans are well known, EPA determined that isocyanuric acid can represent all the chlorinated 

isocyanurates for the purpose of conducting metabolism, subchronic, chronic, developmental, 

and mutagenicity studies.” 

No additional studies have been submitted to the Agency and no public literature was found that 

was dated after the HIARC report was written.

Acute Toxicity for Product Labeling 

The acute toxicity profile for isocyanuric acid, as represented by data on the chlorinated 

isocyanurate compound trichloro-s-triazinetrione, is listed in Table 13. The acute toxicity is 

minimal by the oral, dermal, and inhalation routes of exposures, (Toxicity Category III for oral 

and dermal, Toxicity Category IV for inhalation). However, the isocyanurates demonstrate 

significant irritation to the skin and eyes (Toxicity Category I) and are also dermal sensitizers. 

Table 13 - Acute Toxicity of the Chlorinated Isocyanurates 

Guideline 

No. Study Type MRIDs # Results Toxicity Category

81-1 Acute Oral 00150959 LD50 = 787 mg/kg (M) and 868 mg/kg (F) III 

81-2 Acute Dermal 42180403 LD50 > 2000 mg/kg III 

81-3 Acute Inhalation LC50 > 200 mg/L IV 

81-4 Primary Eye Irritation 00019754 severe eye irritant I 

81-5 Primary Skin Irritation 00019754 severe dermal irritant I 

81-6 Dermal Sensitization 00144720 dermal sensitizer 

81-8 Acute Neurotoxicity N/A N/A 

Subchronic Toxicity 

In subchronic toxicity tests (MRIDs #0063477 and MRID #00124782), the dose levels in rats 

and mice at which toxicity is manifested are considered high (LOAELs of 672 mg/kg/day in rats, 
Page 44 of 52

LOAEL > 1994 mg/kg/day in mice). There were no reported signs of toxicity after 13-week 

administration of the test chemical to mice, and in rats, toxicity was manifested in the urinary 

bladder as hyperplasia of the urinary bladder epithelium, a known toxic response to 

isocyanurates at high dose levels as a result of precipitation of the chemical in the bladder. 

Developmental and Reproductive Toxicity 

In developmental toxicity tests, isocyanuric acid at doses up to 500 mg/kg/day in rabbits (MRID 

#42054101) and 5000 mg/kg/day in rats (MRID #00105168) caused no significant maternal or 

developmental toxicity. 

In reproductive toxicity testing, isocyanuric acid produced calculi in the urinary bladder in 

parental rats of the F2 generation at doses approximating a limit dose of 1000 mg/kg/day, while 

there were no reported reproductive or fertility effects in offspring of any generation at doses up 

to and including a limit dose of 1000 mg/kg/day (MRID #00150286). In one study with 

monosodium isocyanurate in rabbits (MRID #42054101), increased fetal and litter incidence of 

hydrocephaly was observed in offspring at a dose of 500 mg/kg/day, a dose which was not 

maternally toxic. The weight of the evidence suggests no developmental or reproductive toxicity 

from exposure to isocyanuric acid, but the results of the single rabbit study must also be 

considered. 

Chronic Toxicity and Carcinogenicity 

Isocyanuric acid has been adequately tested for chronic toxicity and carcinogenicity in studies 

with rats (MRID #00126362) and mice (MRID #00126361). In both of these studies, 

isocyanuric acid was found to be devoid of carcinogenic effects. Although epithelial hyperplasia 

was observed in the rat study, this is known to be a result of calculi formation in male rat bladder 

as a result of precipitation of the test chemical in urine at high doses and as a result of the pH of 

rodent urine. 

Mutagenicity 

The negative results of carcinogenicity testing are supported by the results of mutagenicity 

testing (MRIDs #0094883, #0091031 and #0094882) of isocyanuric acid that shows the chemical 

to be negative in all mutagenicity assays submitted to the Agency. 
Page 45 of 52

Appendix C: Ecotoxicology Profile 

A review of toxicity effects data for the chlorinated isocyanurates is summarized in the following 

sections, with selected ecotoxicological endpoints for risk assessment provided in Table 1. 

Additional toxicity information is obtained from the EPA Office of Water’s Ambient Water 

Quality Criteria for Chlorine - 1984 (EPA 1985). The document contains a review of public 

literature on effects of chlorine and based on the data derives freshwater and saltwater organism 

acute and chronic water quality criteria as total chlorine residual (TRC) for freshwater and total 

residual oxidant (TRO) for seawater. Current ambient water quality criteria for chlorine or total 

chlorine residual are based on the data in the 1984 document and the method for deriving water 

quality standards discussed in a 1986 Water Quality Document (USEPA, 1986). 

 Freshwater Criterion Maximum Concentration = 19 μg/L; 

 Freshwater Criterion Continuous Concentration = 11 μg/L; 

 Saltwater Criterion Maximum Concentration = 13 μg/L; and 

 Saltwater Criterion Continuous Concentration = 7.5 μg/L 

Terrestrial - Avian acute-oral and dietary toxicity

An acute oral toxicity study using the technical grade of the active ingredient (parent 

compounds, i.e. TGAI) is anticipated to be required to establish the toxicity of the chlorinated 

isocyanurates to birds. The preferred test species is either the mallard (Anas platyrhynchos) or 

the northern bobwhite (Colinus virginianus). Data for both mallard and northern bobwhite have 

been submitted for trichloro-s-triazinetrione (Table 14), sodium dichloroisocyanurate dihydrate 

(Table 15), and sodium dichloro-s-triazinetrione (Table 16). Those 10 studies categorize the 

chlorinated isocyanurates (TGAI) as being slightly to practically nontoxic to birds on an acuteoral basis (LD50’s = 1021 to >2250 mg ai/kg-bw). The guideline requirement (850.2100) is 

satisfied. Chronic data (850.2300) are not expected to be required. 

Avian dietary toxicity studies (850.2200) are not expected to be required for the current uses. 

However, 14 studies were submitted for trichloro-s-triazinetrione, sodium dichloro-striazinetrione, and sodium dichloroisocyanurate dihydrate for both mallard and northern 

bobwhite. Those data categorize the chlorinated isocyanurates (TGAI) as being practically 

nontoxic to birds on a dietary basis (LC50’s >5000 ppm). 
Page 46 of 52

Table 14 Available Endpoints from Avian Ecotoxicity Studies for Trichloro-striazinetrione 

Study Type Species 

Test 

material 

(% ai) 

Toxicity1 Toxicity 

Classification 

MRID & 

Status 

Acute – Avian 

Oral 

850.2100 

Northern 

bobwhite 

92 LD50: 1674 mg/kg-bw/day Slightly toxic 00150962 

Acceptable 

99 LD50: >2250 mg/kg-bw/day Practically 

nontoxic 

00144303 

Supplemental 

Mallard 

100 LD50: 1890 mg/kg-bw/day Slightly toxic 00132603 

Supplemental 

100 LD50: 1021 mg/kg-bw/day Slightly toxic 00126521 

Acceptable 

Acute – Avian 

Dietary 

850.2200 

Northern 

bobwhite 

100 LC50: 7235 ppm Practically 

nontoxic 

0019380 

Acceptable 

92 LC50: >5000 ppm Practically 

nontoxic 

00150964 

Acceptable 

99 LC50: >5000 ppm Practically 

nontoxic 

00144302 

Supplemental 

Mallard 

100 LC50: >10,000 ppm Practically 

nontoxic 

00132426 

Acceptable 

92 LC50: >5000 ppm Practically 

nontoxic 

00150963 

Supplemental 

99 LC50: >5620 ppm Practically 

nontoxic 

00144301 

Supplemental 1

 Toxicity values based on parent compound (TGAI). 

Table 15 Available Endpoints from Avian Ecotoxicity Studies for Sodium 

Dichloroisocyanurate Dihydrate 

Study Type Species 

Test 

material 

(% ai) 

Toxicity Toxicity 

Classification 

MRID & 

Status 

Acute – Avian 

Oral 

850.2100 

Northern 

bobwhite 

98.3 LD50: 1766 mg/kg-bw/day Slightly toxic 00150947 

Acceptable 

98.13 LD50: 1766 mg/kg-bw/day Slightly toxic 256739 

Acceptable 

Acute – Avian 

Dietary 

850.2200 

Northern 

bobwhite 98 LC50: >5000 ppm Practically 

nontoxic 

256739 

Acceptable 

Mallard 98 LC50: >5,000 ppm Practically 

nontoxic 

256739 

Acceptable 1

 Toxicity values based on parent compound (TGAI). 
Page 47 of 52

Table 16 Available Endpoints from Avian Ecotoxicity Studies for Sodium Dichloro-sTriazinetrione 

Study Type Species 

Test 

material 

(% ai) 

Toxicity Toxicity 

Classification MRID & Status 

Acute – Avian 

Oral 

850.2100 

Northern 

bobwhite 

98 LD50: 1766 mg/kg-bw/day Slightly toxic 256739 

Acceptable 

98.3 LD50: >2250 mg/kg-bw/day Practically 

nontoxic 

254911 

Acceptable 

Mallard 

100 LD50: 1915 mg/kg-bw/day Slightly toxic 00125993 

Supplemental 

100 LD50: 1916 mg/kg-bw/day Slightly toxic 241226 

Acceptable 

Acute – Avian 

Dietary 

850.2200 

Northern 

bobwhite 

98 LC50: >5600 ppm Practically 

nontoxic 

254910 

Acceptable 

98.3 LC50: >5000 ppm Practically 

nontoxic 

256739 

Acceptable 

100 LC50: >10,000 ppm Practically 

nontoxic 

0019608 

Acceptable 

Mallard 

100 LC50: >10,000 ppm Practically 

nontoxic 

00007219 

Acceptable 

98 LC50: >5620 ppm Practically 

nontoxic 

254909 

Acceptable 

98.3 LC50: >5000 ppm Practically 

nontoxic 

256739 

Acceptable 

1

 Toxicity values based on parent compound (TGAI).

Mammals

The chlorinated isocyanurates are slightly toxic to mammals on an acute basis (LD50 = 787 to 

868 mg/kg-bw; MRID 00150959 (see Appendix B)). Developmental and reproductive toxicity is 

not expected from exposure to the degradate, isocyanuric acid (see Appendix B). In reproductive 

toxicity testing with rats, isocyanuric acid produced no reported reproductive or fertility effects 

in offspring of any generation at doses up to and including a limit dose of 1000 mg/kg-bw/day 

(MRID #00150286). In one study with monosodium isocyanurate in rabbits (MRID 

#42054101), increased fetal and litter incidence of hydrocephaly was observed in offspring at a 

dose of 500 mg/kg-bw/day, a dose which was not maternally toxic. 

Nontarget Terrestrial Insects

Data are not expected to be required for the chlorinated isocyanurate uses because exposure is 

unlikely given the use pattern and fate of the chlorinated isocyanurates and there degradates. 
Page 48 of 52

Aquatic - Freshwater Fish and Invertebrate Toxicity

According to the Office of Water’s Ambient Water Quality Criteria for Chlorine – 1984

(AWQC, EPA 1985), the term “total residual chlorine” (TRO) refers to the sum of free chlorine 

and combined chlorine in fresh water. In saltwater, in which chlorine forms will react with 

bromide, “chlorine-produced oxidants” (CPO) is used to refer to the sum of the oxidative 

products. Therefore, the toxicity values presented in this document, expressed as μg ai/L, refer 

to TRO for freshwater organisms and CPO for saltwater organisms.

Acute toxicity data requirements and toxicity endpoints for freshwater and saltwater fish and 

invertebrates are presented below. Chronic data are anticipated to be required as none are 

available for either fish or invertebrates.

Freshwater Fish

To assess potential acute and chronic risks to aquatic freshwater fish, acute and chronic effects 

data are anticipated to be required for the TGAI. The preferred test species are rainbow trout 

(Oncorhynchus mykiss), a coldwater species, and bluegill sunfish (Lepomis macrochirus), a 

warmwater species. The 19 available studies for trout and bluegill categorize the four 

chlorinated isocyanurates tested as being mostly highly toxic to freshwater fish (LC50’s = 80 to 

1720 μg ai/L). No additional acute data are needed. Acute toxicity data for freshwater fish and 

invertebrates are available for trichloro-s-triazinetrione (Table 17), sodium dichloro-striazinetrione (Table 18), sodium dichloroisocyanurate dihydrate (Table 19), and potassium 

dichloroisocyanurate (Table 20). Chronic data (early-life stage toxicity, guideline 850.1400) are 

anticipated to be required. 

Freshwater Invertebrates

Data are anticipated to be required to assess potential acute and chronic risks to aquatic 

freshwater invertebrates. The preferred test species is Daphnia magna or Daphnia pulex. 

Twelve studies have been submitted. The data categorize the four chlorinated isocyanurates 

tested as being highly toxic to freshwater invertebrates (LC50’s = 110 to 800 μg ai/L). The 

guideline requirement for acute testing (OCSPP 850.1010) is satisfied. No additional acute data 

are anticipated to be needed. However, chronic data (life stage toxicity, guideline 850.1300) are 

anticipated to be required. 

Estuarine and Marine Organisms

TGAI data are required to assess acute and chronic risks to estuarine/marine fish and 

invertebrates potentially exposed from use of chlorinated isocyanurates in industrial processes 

and water systems. The preferred test species are the sheepshead minnow (Cyprinodon 

variegatus), Eastern oyster (Crassostrea virginica), and mysid shrimp (Mysidopsis bahia). No 

data have been submitted for the TGAI. Data submitted to support sodium hypochlorite, which 
Page 49 of 52

also generates hypochlorous acid, indicates that hypochlorous acid (11.43-12.96% ai) is highly to 

very highly toxic to estuarine/marine fish (LC50’s = 50 and 380 μg ai/L) and invertebrates 

(LC50’s = 160 and 200 μg ai/L). Those data were generated using sodium hypochlorite 

formulations and do not support the TGAI. However, data are available in the AWQC (EPA 

1985) indicating that CPO is highly to very highly toxic to estuarine/marine fish and 

invertebrates (Table 17). No additional acute data are needed. However, chronic data for fish 

(early life stage toxicity, guideline 850.1400) and invertebrate (life stage toxicity, guideline 

850.1350) are required. 

Table 17 Available Acute Endpoints from Freshwater Fish and Aquatic Invertebrate 

Ecotoxicity Studies for Trichloro-s-triazinetrione 

Study Type Species 

Test 

material 

(% ai) 

Toxicity Toxicity 

Classification 

MRID & 

Status 

Acute – 

Freshwater Fish 

850.1075 

Rainbow 

trout 

100 96-hr LC50: 330 μg ai/L Highly toxic 26195 

Acceptable 

100 96-hr LC50: 370 μg ai/L Highly toxic 26193 

Acceptable 

92 96-hr LC50: 80 μg ai/L Very highly 

toxic 

00150966 

Acceptable 

Bluegill 

100 96-hr LC50: 200 μg ai/L Highly toxic 00150965 

Acceptable 

92 96-hr LC50: 200 μg ai/L Highly toxic 00150965 

Supplemental 

100 96-hr LC50: 620 μg ai/L Highly toxic 26194 

Supplemental 

Acute – 

Freshwater 

Invertebrate 

850.1010 

Waterflea 

92.8 48-hr EC50: 170 μg ai/L Highly toxic 00150967 

Acceptable 

100 48-hr EC50: 800 μg ai/L Highly toxic 00154329 

Acceptable 

98 48-hr EC50: 640 μg ai/L Highly toxic 00150967 

Acceptable 

NR 48-hr EC50: 250 μg ai/L Highly toxic 00019766 

Supplemental 

Table 18 Available Acute Endpoints from Freshwater Fish and Aquatic Invertebrate 

Ecotoxicity Studies for Sodium Dichloro-s-Triazinetrione 

Study Type Species 

Test 

material 

(% ai) 

Toxicity Toxicity 

Classification 

MRID & 

Status 

Acute – 

Freshwater Fish 

850.1075 

Rainbow 

trout 

100 96-hr LC50: 358 μg ai/L Highly toxic TN1038 

Acceptable 

98.3 96-hr LC50: 250 μg ai/L Highly toxic 256739 

Acceptable 
Page 50 of 52

Study Type Species 

Test 

material 

(% ai) 

Toxicity Toxicity 

Classification 

MRID & 

Status 

63 96-hr LC50: 240 μg ai/L Highly toxic 00019523 

Supplemental 

Bluegill 

100 96-hr LC50: 1720 μg ai/L Moderately 

toxic 

TN1039 

Acceptable 

100 96-hr LC50: 810 μg ai/L Highly toxic TN368 

Supplemental 

63 96-hr LC50: 283 μg ai/L Highly toxic 251231 

Supplemental 

57 96-hr LC50: 2400 μg ai/L Moderately 

toxic 

TN1030 

Acceptable 

Acute – 

Freshwater 

Invertebrate 

850.1010 

Waterflea 

98 48-hr EC50: 110 μg ai/L Highly toxic 255593 

Acceptable 

98.3 48-hr EC50: 280 μg ai/L Highly toxic 256739 

Acceptable 

55.63 48-hr EC50: 199 μg ai/L Highly toxic 00007241 

Supplemental 

NR 48-hr EC50: 220 μg ai/L Highly toxic 00019310 

Supplemental 

Table 19 Available Acute Endpoints from Freshwater Fish and Aquatic Invertebrate 

Ecotoxicity Studies for Sodium Dichloroisocyanurate Dihydrate 

Study Type Species 

Test 

material 

(% ai) 

Toxicity Toxicity 

Classification 

MRID & 

Status 

Acute – 

Freshwater Fish 

850.1075 

Rainbow 

trout 98 96-hr LC50: 250 μg ai/L Highly toxic 256739 

Acceptable 

Bluegill 98 96-hr LC50: 460μg ai/L Highly toxic 00150950 

Acceptable 

Acute – 

Freshwater 

Invertebrate 

850.1010 

Waterflea 98 48-hr EC50: 460 μg ai/L Highly toxic 00150950 

Acceptable 

Table 20 Available Acute Endpoints from Freshwater Fish and Aquatic Invertebrate 

Ecotoxicity Studies for Potassium Dichloroisocyanurate 

Study Type Species 

Test 

material 

(% ai) 

Toxicity Toxicity 

Classification 

MRID & 

Status 

Acute – 

Freshwater Fish 

850.1075 

Rainbow 

trout 

100 96-hr LC50: 316 μg ai/L Highly toxic 00019316 

Acceptable 

50 96-hr LC50: 750 μg ai/L Highly toxic TN0679 

Supplemental 
Page 51 of 52

Study Type Species 

Test 

material 

(% ai) 

Toxicity Toxicity 

Classification 

MRID & 

Status 

Bluegill 100 96-hr LC50: 490 μg ai/L Highly toxic 00019316 

Supplemental 

Brook trout 100 96-hr LC50: 278 μg ai/L Highly toxic TN01107 

Supplemental 

Acute – 

Freshwater 

Invertebrate 

850.1010 

Waterflea 

100 48-hr EC50: 170 μg ai/L Highly toxic 234257 

Acceptable 

50 48-hr EC50: 660 μg ai/L Highly toxic TN0868 

Acceptable 

NR 48-hr EC50: 170 μg ai/L Highly toxic 00019311 

Supplemental 

Aquatic Plants

Aquatic plant-growth data are anticipated to be required to support the industrial processes and 

water systems uses. Data are anticipated to be required for one vascular species, Lemna sp. 

(OCSPP 850.4400), three algal species (OCSPP 850.4500), and cyanobacteria (OCSPP 

850.4550). No data have been submitted. 

Isocyanuric acid Toxicity

No effects data on cyanurate/isocyanuric acid has been submitted to the OPP for review in 

support of pesticide registration. The Agency recognizes that isocyanuric acid is an EPA high 

production volume10 (HPV) chemical for which a Screening Information Data Set (SIDS) 

Assessment Report was performed (OECD SIDS 1999 and IIHAC 2003). Values found in these 

sources have been listed in the table below and consist of freshwater fish and invertebrate and 

green algae data. While some critical elements of these studies are identified in the HPV SIDS 

files, there is insufficient information available on the studies for AD to review the studies for 

purposes of a risk assessment. ECOSAR v1.1 was used to estimate freshwater and 

estuarine/marine fish and invertebrate acute and chronic values and the median effect 

concentration (EC50) and maximum allowable toxicant concentration (MATC; geometric mean 

of the NOAEC and LOAEC) for green algae. These values are also listed in Table 21. 

Table 21 - Available Aquatic Organism data for Isocyanuric Acid 

Receptor 

Group 

Test 

Materiala Surrogate 

Species 

Risk 

Scenario Toxicity Endpoint Reference/ Study Classification 

Freshwater 

fish 

isocyanuric 

acid 

Generic fish Acute 96-h LC50 = 72.0 mg/L ECOSAR v1.1a

/ 

Acceptable Model 

Rainbow trout Acute 96-h LC50 >2100 mg/Lb IIHAC 2003b

/ 

Unacceptablec

Bluegill Acute 96-h LC50 >1000 mg/Lb IIHAC 2003b

/ 

Unacceptablec

 

10 http://www.epa.gov/hpv/pubs/general/hpvchemdata.htm 
Page 52 of 52

Receptor 

Group 

Test 

Materiala Surrogate 

Species 

Risk 

Scenario Toxicity Endpoint Reference/ Study Classification 

Fathead 

minnow Acute 96-h LC50 >1000 mg/Lb IIHAC 2003b

/ 

Unacceptablec

Japanese 

medaka Acute 96-h LC50 >100 mg/L OECD SIDS 1999/ 

Unacceptablec

Generic fish Chronic MATC = 1.85 mg/L ECOSAR v1.1a

/ 

Acceptable Model 

Freshwater 

invertebrates 

isocyanuric 

acid 

Daphnid Acute 48-h EC50 = 24.6 mg/L ECOSAR v1.1a

/ 

Acceptable Model 

Daphnid Chronic MATC = 1.49 mg/L ECOSAR v1.1a

/ 

Acceptable Model 

Waterflea Acute 48-h EC50 = 1000 mg/Lb OECD SIDS 1999b

/ 

Unacceptablec Chronic NOEC = 65,900 μg/Lb

Estuarine/marine 

fish 

Isocyanuric 

acid 

Generic Acute 96-h LC50 = 46.9 mg/L ECOSAR v1.1a

/ 

Acceptable Model 

Generic Chronic MATC = 2.45 mg/L ECOSAR v1.1a

/ 

Acceptable Model 

Estuarine/marine 

invertebrates 

Isocyanuric 

acid 

Mysid Acute 96-h LC50 = 6.98 mg/L ECOSAR v1.1a

/ 

Acceptable Model 

Mysid Chronic MATC = 4.82 mg/L ECOSAR v1.1a

/ 

Acceptable Model 

Algae isocyanuric 

acid Green algae 

EC50 96-h EC50 = 0.114 mg/L ECOSAR v1.1a

/ 

Acceptable Model 

NOAEL MATC = 0.057 mg/L ECOSAR v1.1a

/ 

Acceptable Model 

EC50 96-h EC50 = 712 mg/Lb IIHAC 2003b

/ 

Unacceptablec

EC50 72-h EC50 = 620 mg/Lb OECD SIDS 1999b

/ 

Unacceptablec NOAEL 62.5 mg/Lb

MATC (maximum allowable toxicant concentration) = geometric mean of the NOEC and LOEC 

a ECOSAR v1.1 class specific estimations for aromatic triazines. b

 While some critical elements of these studies are identified in the HPV SIDS files, there is insufficient information 

available on the studies for AD to review the studies for purposes of a risk assessment. These studies would need to 

be submitted for review by AD for incorporation in a risk assessment. 

c

 Study value is from a secondary source; the original study is not available. There is insufficient information 

available on the study to allow AD to conduct a review for determination of acceptability for use in a risk 

assessment.