**-,~EO S"'-4~** 

### .~~**~d\.** 

# $' 

# U UNITED STATES ENVIRONMENTAL PROTECTION AGENCY S 

## @ WASHINGTON D.C., 20460
:xJ <!l 

# <i 'If**~ ~** 

### ~~**~~**

## ~L.**PRO'1~(j**

MEMORANDUM

SUBJECT: OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION



### December 21

, 2011

Product Chemistry, Environmental Fate, and Ecological Effects Scoping
Document in Support of Registrati on Review of Methylene bis( thiocyanate)

PC Code: 068102 DP Barcode: 394334 Decision No.: 455140 Re g istration Nos

. : See Table 1 Petition No(s).: NA Regulatory Action: Ecological Environmental Scoping Document for Re g istration Review Risk Assessment Type: Single Case No.: 2415 chemical
TXRNo.:NA CAS No.: 6317-18-6
MRID Nos.:See Tables 2

, 3 & 4 and 40 CFR : None P g .no.5



### FROM: 1r= srinivas Gowda, Microbiolo



### THRU:

TO:

### William Erickson, Biologist

### ~~:::::::~vv.. 

## .....**~~~,Jj/.l)J~** Najm Shamim, Chemist Risk Assessment and Science Support Branch (RASSB)
Antimicrobials Division (751 OP) -<..**~**



### Nader Elkassabany, Branch

# ~**~ ~**  , _ n 

### Donna Randall, Peer Reviewer

## 'V\...~ 1'l-/2...I/t( 

### Risk Assessment and Science Support Branch (RASSB) Antimicrobials Division (751 OP)

Mark Hartman, Branch Chief
Lance Wormell, Team Leader Rebecca von dem Hagen, Chemical Review Manager Regulatory Management Branch II Antimicrobials Division (751 OP)

Page 1 of28

### Page 2 of 28 Executive Summary

Methylene bis(thiocyanate) (MBT) an organothiocyanate compound is registered for use

as a material preservative

, wood preservative and as a microbiocide/microbiostat in indus trial process and water systems

. MBT was first registered in the United States in 1949 as an active ingredient. A Reregistration Eligibility Decisi on (RED) was issued by EPA for m ethylene bis(thiocyanate) in 1997

. Currently there are fifteen companies with a total of 40 active registrations. Six of the products are registered as a technical with an active ingredient declaration of 98.95 to 99%. The remaining 34 products are registered end

- use products with active ingredient declarations ranging from 2.5 to 10%; these products consist of soluble ready

to

- use solutions, flowable soluble concentrates, solid soluble concentrates, wettable powders, and emulsifiable concentrat es. All product chemistry data requirements have been satisf ied for this active ingredient.

At the time of the RED, risk assessments were not conducted for industrial microbiocides unless products had a once

- through cooling water system use. To regulate these industrial microbiocide uses and associated risks to the aquatic environment, the Agency required that labels for MBT products require that discharges to aquatic environments comply with a National Pollutant Discharge Elimination System (NPDES) perm it. As part of the registration review process, risk assessments for the material preservative, wood preservative and industrial process and water systems will be conducted.

To conduct these assessments, the Agency data base for evaluating the environme ntal fate and transport of MBT is incomplete. The environmental fate data gaps for this antimicrobial include aqueous photolysis at pH 5, soil adsorption/desorption study, aerobic and anaerobic aquatic metabolism studies, activated sludge respiration inhibition, and one of four waste biodegradability tests (ready biodegradability, porous pot test, or one of two simulation tests). The purpose of these tests is to address discharge of fluids from industrial process and water systems, cooling water systems (recirculating), pulp and paper mills, oil and gas well production systems, metal working fluids and wood preservatives. In terms of what is known about the environmental fate of MBT it i s hydrolytically stable at pH 5, but degrades easily at pH 7 and 9. It is not likely to bioaccumulate as its Log K ow 

### is around 2. Through the hydroly sis and photolysis from the wood surfaces, the common degradates formed are: thiocyanate, formic acid, and carbon dioxide. Under environmenta l conditions formation of cyanide from the thiocyanate moiety is not known to occur.

MBT is highly to very highly toxic to freshwater and estuarine/marine animals and is highly toxic to birds on an acute oral basis. In order to perform an ecological ri sk assessment, including an endangered species determination for all uses, the Agency anticipates needing a freshwater fish early

- life stage study, a vascular aquatic plant (Tier II) toxicity study, aquatic plant (Tier II) toxicity tests with 4 algae speci es, a honeybee acute contact study, a residue toxicity to honeybee study and a freshwater invertebrate sediment study.

### Page 3 of 28 Introduction

MBT was first registered in the United States in 1949 as an active ingredient. Currently, 40 products are registered which are listed in Table 1 (Appendix C) for incorporation into products such as adhesives, coatings, fuels, metalworking cutting fluids, t extiles, plastic products, resin emulsions, paints, paper products and various other products as a material preservative ; and as a microbiocide in pulp/paper mills, cooling water systems (recirculating), oil field operations, air washer systems, brewery p a teurizers, hydrotesting, leather processing and industrial water supply systems. MBT is also used for wood sapstain control and mold on freshly cut hardwood and softwood lumber, logs, poles, posts and timbers

. A Reregistration Eligibility Decisi on (RED) w as issued by EPA for m ethylene bis(thiocyanate) in 1997 1



### .
The Agency has conducted a review of the available product chemistry, environmental fate, and ecotoxicity data for m ethylene bis(thiocyanate)

. The primary source of information for this assessment was the 1997 m ethylene bis(thiocyanate) RED. The findings are summarized below.

A. Product Chemistry Summary of Methylene bis(thiocyanate) ( 98 % Min. TGA I )

Common Name: Methylene bis(thiocyanate) (MBT) Methylene dithiocyanate Thiocyanic acid, methylene ester

Chemical Name: Methylene bis(thiocyanate)

Trade and Other Names: Slimicide MC Busan 110 Nalco D

- 1994 Antiblu 3737 Cytox

OPP Chemical Code: 068102

CAS Registry Number: 6317

- 18

- 6

Molecular Formula: C 3 

### H 2 

### N 2 

### S 2 

### CH 2 

### (SCN) 2 

### Molecular weight: 1 30.2 g/mole

Molecular Structure: N ≡C

- ―S―CH2―S―C ≡N

Color: Yellow to light orange solid

.

1 http://www.epa.gov/oppsrrd1/REDs/2415red.pdf

### Page 4 of 28 Physical State: Solid, granular

.

Odor: Sul fur like smell

.
Stability: Stable when stored for 14 days exposed to the following conditions: ambient temperature, broad

- spectrum light, stainless steel, galvanized steel, aluminum, copper, iron (III ) oxide, aluminum tartrate, and copper acetate. Loss of active ingredient was observed when stored for 14 days with zinc acetate.

M BT is stable as a bulk chem ical for 2 weeks at temperatures up to 60 ° C when stored capped with a nitrogen headspace and protected from l ight.

Oxidation/Reduction: No reaction observed under ambient conditions when mixed with tap water, hexane, monoammonium phosphate, or zinc; mild reaction with potassium permanganate solution.

Flammability : Not applicable for products which do not con ta in combustible liquids

.
Explodability: Contains no explosive ingredients

.
Storage Stability: No evidence of degradation or decomposition was observed during the GC analysis of the stability samples. Visual inspection of the samples at the end of the 12

- month storage period detected no evidence of physical change, such as clumping or discoloration. The amount of MBT determination for each analys is indicated that MBT was stable for one year under the conditions of the study.

Storage stability at room temperature (18 mo nths ) and at 55 ° C (8 wks.): Stable

.
Miscibility: Not applicable to products not intended to be diluted with petroleum solvents

.

Corrosion Characteristics: After storage in contact with the technical grade MBT at 54 ° C for 30 days, a color cha nge was observed for the sample; however, no signs of corrosion were evident in the packaging material

.

Dielectric breakdown voltage: 

### Not applicable to products not intended to be used around electrical equipment

.

### Page 5 of 28 p H : Not applicable to solids

.
UV/Visible absorption: Not Reported

.
Viscosity: Not applicable to solid products

.
Melting point: Sample melted over a range of 105.4 to 106.8 ° C with no observed decomposition. ( 105

- 107 ° C )

.
Boiling Point: N/A, MBT is a solid at room temperature

.
Density: 0.820 g/mL

Dissociation Constant: It is non

- ionic. Not determined because MBT was found to be unstable at pH levels higher than nine or lower than three , a spectrometric determination is not possible

.
Log K o/w 

### : K o/w 

### (~0.01M solution) 2.2 ± 0.4 (s) K o/w 

### (~0.0 0 1M solution) 2.1 ± 0.3 (d)

Solubilit ies : Its solubilities are 0.28, 0.35 and 5.1 g/ 100 mL in water, octanol and methanol, respectively at 25 ° C

. Soluble in water

.
Vapor Pressure: 1.22 x 10 - 4 

### mm Hg at 26 ± 1°C

Henry's Law Constant: 2.61 E

- 008 atm

- m3/mole ( Source: EPI Suite)

Enf orcement Analytical Method: Gas Chromatography ; High Pressure Liquid Chromatography ( HPLC )

.


### All product chemistry data requirements have been satisfied for the active ingredient M BT

. (Source: MRID s 41648001, 41607701, 41611902, 41611901, 40518601, 42739201, 41611901, 42739202, 41607702, 41648002, 40518602, 40518602, 41648003, 41982101, and 43328601 )

.



### B. Environmental Fate Summary

No environmental fate assessment was performed for MBT at the time of the registration

. Available environmental fate guideline studies and the results are summarized in Table 2

.
The Agency's conclusions for the degradati on and aqueous availa bility or leaching studies are summarized in Table 2 below

.

### Page 6 of 28 Table 2

. Environmental Fate Data Summary for MBT Guide line No. Data Type Summary MRID No. 161

- 1 Hydrolysis Stable at pH 5; half life at pH 7 = 6.18 days; half life at pH 9 = 2.22 hours; major degradates: thiocyanate, formic acid, and carbon dioxide 43092101

Non

Guideline Study Photolysis on treated Wood pieces Treated Wood pieces irradiated with artificial light for 360 hours. MBT

- treated pine wood surfaces: half life: 61 days; MBT

- treated oak wood: half life: 48 days; MBT treated. Degradate identified: thiocyanate 43511101

Non

Guideline Study Aqueous Availability or Leaching Study Wood pieces were dipped in MBT solution (1000

- 2000 ppm range), and were air dried for 30 minutes or 30 days. The leachates were obtained in buffered medium as well as in artificial sweat solution either on a 30 minute sampling or 21 day sampling. MBT leached > 70% between 3 days to 7 days duration. The most common degradates were: thiocyanate and carbon dioxide, at pH 7, and 9 43545601

In summary, the registrant s ha ve submitted an acceptable hydrolysis study (MRID # 430921

- 01 ), and information on photolysis of MBT on treated wood pieces (MRID # 435111

- 01 ), and a wood leaching study (MRID # 435456

- 01 ). MBT is hydrolytically stable at pH 5, but degrades easily at pH 7 and 9. Through the hydrolysis and photolysis from the wood surfaces, the common degradates formed are: thiocyanate, f ormic acid, and carbon dioxide. The identified degradates of MBT are: formic acid, thiocyanate ions and carbon dioxide which are the ultimate degradation product (mineralization) of MBT. The Agenc y had speculated the formation of cyanide ion as a degradate in the RED document ; h owever, additional data has indicated that the formation o f cyanide ion from thiocyanate is not possible under environmental relevant conditions. Both formic acid wh ich min eralizes into carbon dio x i de under the environmental conditions, and carbon dioxide is itself the mineralized product, the Agency does not inten d to

as k for data on these degradates.

MBT is not likely to bioaccumulate as its Log K ow 

### is around 2.

T he Agency needs to conduct an environmental fate assessment for material preservatives (including MBT ) and industrial slimicides used in recirculating water cooling

towers
, pulp and paper mills , oil and gas well development, metal working fluids and wood
pre servatives that may potentially pass through waste water treatment plants (WWTPs) and may be discharged into terrestrial and aquatic environments

. For this assessment the Agency

### Page 7 of 28 anticipates needing those data outlined on page 10 of this document

. In addi tion, the Agency needs to conduct an environmental fate assessment for MBT used in wood preservatives

.
Water Quality

MBT is not identified as a cause of impairment for any water bodies listed as impaired under section 303(d) of the Clean Water Act, based on information provided at the Agency’s National Pesticides Cause of Impairment of Waters website (searched April 7, 2011) 2



### . In addition, no Total Maximum Daily Loads (TMDL) have been developed for MBT

, based on information provided at the Agency’s National Pesticide TMDL web site (searched April 7, 2011) 3 

### http://www.epa.gov/owow/tmdl/ . More information on impaired water bodies and TMDLs can be found at

. The Agency invites submission of water qu ality data for this pesticide. To the extent possible, data should conform to the quality standards in Appendix A of the OPP Standard Operating Procedure: Inclusion of Impaired Water Body and Other Water Quality Data in OPP’s Registration Review Risk Assessment and Management Process (see: http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1

- sop.pdf ), in order to ensure they can be used quantitatively or qualitatively in pes ticide risk assessments.

C. Ecological Effects Summary

No quantitative ecological risk assessment was performed for MBT at the time of the RED

. Available ecotoxicity guideline studies are summarized in Tables 3 and 4

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

a. Toxicity to Terrestrial Organisms

MBT is highly toxic to birds on an acute

- oral basis (LD 50 

### s = 45

- 50 mg/kg

- bw/day) but is practically nontoxic on a dietary basis (LC 50 

### s >5000 ppm). A summary of the avian toxicity data endpoints from registrant

- submitte d studies is provided in Table 3 . Insect pollinator data are required but not available . Mammalian toxicity data are not required, but acute and chronic data are available in the human health sco ping document.

Table 3

. Summary of the Endpoints from Submitted Terrestrial Toxicity Studies for M BT

Study Type Species Toxicity Value Toxicity Classification MRID & Status

Acute

– Avian Oral 850.2100 Northern Bobwhite (Colinus virginianus ) LD 50 : 50 mg/kg

- bw/day Highly toxic 150232 Acceptable

Acute

– Avian Oral 850.2100 Mallard ( Anas platyrhynchos ) LD 50 : 45 mg/kg

- bw/day Highly toxic 150231 Acceptable

2

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

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

### Page 8 of 28 Table 3

. Summary of the Endpoints from Submitted Terrestrial Toxicity Studies for M BT

Study Type Species Toxicity Value Toxicity Classification MRID & Status

Acute

– Avian Dietary 850.2200 Northern Bobwhite (Colinus virginianus ) LC 50 : >5000 mg/kg

- diet Practically nontoxic 150233 Acceptable

Acute

– Avian Dietary 850.2200 Mallard ( Anas platyrhynchos ) LC 50 : >5000 mg/kg

- diet Practically nontoxic 150232 Acceptable



### b. Toxicity to Aquatic Organisms

A summary of acute and chronic aquatic ecotoxicity data endpoints from registrant

submitted studies is provided in Table 4

. MBT is highly to very highly acutely toxic to freshwater and estuarine/marine fish (LC 50 

### s = 89 to 606 μg/L) and very highly toxic to aquatic invertebrates (EC 50 

### and LC 50 

### s = 3 to 61 μg/L). Chronic data are available for a freshwater invertebrate but not for fish. Reproduction and growth of water fleas were adversely affected at 16 μg/L (NOAEC = 5.8 μg/L) chronic exposure. Acute and chronic data for sediment

- dwelling organisms are not ava ilable.

Table 4 . Summary of the Endpoints from Submitted Aquatic Toxicity Studies for M BT

Study Type Species Toxicity Value Toxicity Classification MRID & Status

Acute

– Freshwater Fish 850.1075 Rainbow trout (Oncorhynchus mykiss ) 96

- hr LC 50 : 89 μg/L Very highly toxic 405186

- 09 Acceptable

Acute

– Freshwater Fish 850.1075 Bluegill sunfish ( Lepomis macrochirus ) 96

- hr LC 50 : 250 μg/L Highly toxic 405186

- 08 Acceptable

Acute

– Estuarine/Marine Fish 850.1075 Sheepshead minnow (Cyprinodon variegatus ) 96

- hr LC 50 : 606 μg/L Highly toxic 425134

- 02 Acceptable

Acute

– Freshwater Invertebrate

850.1010 Water flea ( Daphnia

magna ) 48

- hr EC 50 : 61 μg/L Very highly toxic 405186

- 01 Acceptable

Acute

– Estuarine/Marine Invertebrate

850.1025 Eastern oyster ( Crassostrea

virginica ) 96

- hr LC 50 : 3 μg/L Very highly toxic 424416

- 01 Acceptable

Acute

– Estuarine/Marine Invertebrate

850.1035 Mysid shrimp ( Americamysis bahia ) 96

- hr LC 50 : 36 μg/L Very highly toxic 425134

- 02 Acceptable

Chronic

– Freshwater Invertebrate

850.1300 Water flea ( Daphnia

magna ) NOAEC: 5.8 μg/L LOAEC: 16 μg/L (reproduction, growth) NA 425170

- 01 Acceptable

### Page 9 of 28 c. Toxicity to Aquatic Plants

Aquatic plant data (vascular and non

- vascular species) are required for the risk

assessment . No data are available.

Adverse Ecological Incidents

There are no reported incidents in the Agency's Ecological Incident Information System (EIIS) regarding MBT. The absence of documented incidents does not necessarily mean that such incidents did not occur.

Ecolog ical Effects Risk Assessment

An ecological risk assessment was not conducted on the MBT’s use patterns described in this document. MBT uses that have potential for environmental exposure are material preservatives , wood preservatives, and industrial slim icides used in recirculating water cooling towers and pulp and paper mills discharges. The Agency needs to conduct environmental fate and ecological risk assessments for material preservatives and industrial slimicides used in recirculating water cooling towers and pulp and paper mills that potentially pass through waste water treatment plants (WWTPs) and may be discharged into terrestrial and aquatic environments. In addition, the Agency needs to conduct an ecological risk assessment for MBT used in woo d preservatives. For this ecological risk assessment, including an endangered species assessment for all uses, t he Agency anticipates needing the ecotoxicity data outlined on page 9 of this document

.
The Agency has not conducted a risk assessment for MBT that supports a complete endangered species effects determination. The ecological risk assessment planned during registration review will allow the Agency to determine whether MBT ’s use has “no effect or “may affect” federally listed threatened or endang ered species (listed species) or their designed critical habitats. When an assessment concludes that a pesticide’s use “may affect” a listed species or its designated critical habitat, the Agency will consult with the U.S. Fish and Wildlife Service and/or National Marine Fisheries Services (the Services), as appropriate.

Environmental Fate and Ecotoxicity Data Gaps and Anticipated Work

Environmental fate and ecological risk assessments have not been conducted for MBT

. The Agency needs to conduct environmental fate and ecological risk assessments for material preservatives and industrial slimicides used in recirculating water cooling towers and pulp and paper mills that potentially pass through waste water treatment plan ts (WWTPs) and may be discharged into terrestrial and aquatic environments. In addition, the Agency needs to conduct an environmental fate and ecological risk assessment for MBT used in wood preservatives. Therefore, the Agency anticipates needing the pro posed environmental fate and ecotoxicity data for MBT and/or any of its major degradation products that are of potential concern for all registered uses of MBT. The following environmental fate and ecotoxicity data are needed to conduct an environmental fa te and ecological risk assessment:

### Page 10 of 28 **•** The Agency anticipates needing the following data to conduct a complete environmental fate assessment for material preservative use, and industrial slimicides used in recirculating water cooling towers and paper mills :

o Activated Sludge Sorption Isotherm (GLN 835.1110);

o Adsorption/Desorption Study (GLN 835.12 3 0);

o Aqueous Photolysis (at pH 5) ( GLN 835.2240) ;

o Aerobic Aquatic Metabolism Study (GLN 835.4300) ;

o Anaerobic Aquatic Metabolism Study (GLN 835.4 4 00) ;

o Activated Sludg e Respiration Inhibition (GLN 850.6800 or OECD 209 ) ; and

o Ready biodegradability (GLN 835.3110), Porous Pot Test (GLN 835.3220), or Simulation Tests to Assess the Biodegradability of Chemicals Discharged to Wastewater (GLN 835.3280), or Simulation Test

- Aero bic Sewage Treatment: A. Activated Sludge Units (GLN 835.3240)

. 4



### .

**•** The Agency anticipates needing the following eco toxicity data in order to conduct a complete ecological risk assessment, including an endangered species assessment for material preservative s and industrial slimicides used in industrial process and water systems and wood preservative uses of MBT :

o Fish early

- life stage toxicity test, freshwater species (GLN 850.1400 ) ;

o Aquatic plant toxicity test, vascular species (GLN 850.4400 ) ;

o Aquatic plant toxicity test, non

- vascular (4 species) (GLN 850.5400) ;

o Honeybee acute contact (GLN 850.3020 ) ;

o Toxicity of residues to honeybees (GLN 850.3030) ;

o Sediment acute toxicity test, freshwater invertebrate (GLN 850.1735 ) ;

o Sediment acute toxicity tes t, marine invertebrate (GLN 850.1740 ) ; and

o Sediment chronic toxicity test, freshwater invertebrate (no guideline number).

The sediment toxicity tests will be waived if acceptable environmental fate data are provided to demonstrate that the half

- life of th e pesticide in the sediment is < 10 days and if all of the following conditions are met: 1) Kd <5 0, 2) Koc <1000, and 3) Kow <3.

4 T he results of the Activated Slu dge Respiration Inhibition Test (ASRI) determine which of these three biodegradation tests are required. If the ASRI test EC 50 is less than or equal to 20 mg/L, then either the (i) Biodegradation in Activated Sludge Study or (ii) Simulation Test

– Aerobic Sewage Treatment: A. Activated Sludge Units or (iii) the Porous Pot Test is required. If the ASRI test EC 50 is greater than 20 mg/L, then the applicant must choose either: (i) Ready Biodegradability or (ii) a) Biodegradation in Activated Sludge or b) Sim ulation Test

– Aerobic Sewage Treatment: A. Activated Sludge Units or c) the Porous Pot Test. If the Ready Biodegradability study is conducted and the test substance passes, then no further testing is required. If, however, the test substance fails the Ready Biodegradability study, then the (i) Biodegradation in Activated Sludge or (ii) Simulation Test

– Aerobic Sewage Treatment: A. Activated Sludge Units, or (iii) the Porous Pot study is required.

### Page 11 of 28 Facility Emissions to WWTP Modeling

For assessing the fate of MBT and its major degradates

, emitted to receiving waters from industrial process water uses of MBT such as at pulp and paper mills, for recirculating cooling towers, and oil and gas well development, metal working fluids and wood preservatives the Agency anticipates using the a vailab le environmental fate information from guideline studies for MBT and its major degradates, and the following emission scenarios.

**•** Potential environmental releases and associated exposures of concern for antimicrobial uses related to the Pulp, Paper, and Bo ard Industry will be those identified in "Emission Scenario Documents on Pulp, Paper, and Board Industry", Number 23 of OECD Series on Emission Scenario Documents dated July 8, 2009

.

**•** Potential environmental releases and associated exposures of concern for antimicrobial uses related to the Oil and Gas Well Production Industry will be those identified in the latest version of the OECD Emission Scenario Document for the Oil Well Production Industry or those identified in the latest version of Generic Scenarios developed by the Chemical Engineering Branch of EPA/OCSPP/OPPT/CEB (Chemical Engineering Branch) . On

- shore operations assume potential for disposal of drilling fluids and produce water to public or industrial waste treatment facilities and off

- shore oper ations assume emissions directly to the surrounding water, post

- treatment for removal of oil.

**•** Potential environmental releases and associated exposures of concern for uses of antimicrobial uses related to recirculating cooling towers will be assessed using the Generic Scenarios for recirculating cooling towers developed by the Chemical Engineering Branch of EPA/OCSPP/OPPT/CEB and modified for use for antimicrobials by the Antimicrobial Division.

Facility information needed to estimate aquatic exposures fro m emissions to WWTP for each emission scenario and directly to water from the oil and gas well development sites include the following:

**•** The number of pulp and paper mill sites using MBT or the maximum annual production volume of MBT used in pulp and paper mills in the United States and its territories;

**•** The number of recirculating cooling tower sites using MBT or the maximum annual production volume of MBT used in cooling towers in the United States and its territories;

**•** The number of oil and gas well develo pment sites using MBT or the maximum annual production volume of MBT used in oil and gas well development in the United States and its territories;

**•** The number of metalworking fluid sites using MBT or the maximum annual production volume of MBT used in met alworking fluid preservatives in the United States and its territories;

**•** How many of each of these facilities has on

- site and/or off

- site wastewater treatment.

### Page 12 of 28 Facility information needed to estimate aquatic exposures from emissions to WWTP from the indust rial wood preservative process include the following:

**•** The number of facilities that pressure treat wood products with thiamethoxam; and

**•** How many of these facilities have on

- site and/or off

- site wastewater treatment.

In the absence of information on the n umber of these facilities that use MBT and how many of these facilities have on

- site and/or off

- site wastewater treatment, the Agency will assume that all such facilities in the United States have the potential to use MBT.

In the absence of appropriate t est data on biodegradation during wastewater treatment, the Agency will assume that there is no removal of MBT and its major toxic degradate s during wastewater treatment and that the amount of MBT and its major degradate released with the effluent from a w astewater treatment facility will be the same as the amount entering the wastewater treatment facility. In the absence of data on the percent removal of MBT and its major degradate during drinking water treatment the Agency will assume there is no removal of MBT or its major toxic degradate s

.

### Page 13 of 28 

## Appendix A. Environmental Fate Guideline Study Justifications

Study Title: Activated Sludge Sorption Isotherm Guideline Number: 835.1110 Test Substance: TGAI Rationale for Requiring the Data Data from this study are needed to determine the sorption potential of activated sludge for the removal of specific chemical compounds in biological wastewater treatment plants (WWTPs). No data is currently available. If the chemical is not sorbed or bio degraded, then it would pass through a biological treatment system unaffected, potentially contaminating surface and drinking waters where it may then have the potential to adversely affect non

- target organisms. EPA needs activated sludge sorption study d ata to assess the distribution of the antimicrobial chemical among the solid, aqueous, and vapor phases of WWTPs. Specifically, this study identifies those chemicals which sorb to sludge biomass. Practical Utility of the Data 1. How will the data be used? The data will be used to assess removal of the antimicrobial as a result of sorption to activated sludge. Percent removal via sorption to activated sludge and percent removal via biodegradation are used to determine overall removal of the antimicrobial during wastewater treatment. Over all removal during wastewater treatment is a key input used to determine concentrations of the antimicrobial in surface water immediately downstream of wastewater treatment plants. The concentrations of antimicrobial pesticide immediately downstream of wa stewater treatment plants are used to assess exposure and risk to non

- target endangered and non

- endangered species. Exposure data are integral parts of the risk equation for determining the impact of pesticides to beneficial nontarget organisms through di rect exposure from their food sources and habitat.

In addition, the data will be used to determine whether or not additional studies and/or label restrictions are needed. If the data indicate that the chemical does not sorb to sludge and instead partitio ns more readily to

water and that the chemical does not biodegrade to an appreciable extent then the chemical has the potential to pass through the WWTP and therefore could be discharged in to the aquatic environment. This determination could trigger furt her data requirements to assess the chemical’s impact upon release. If the data indicates relatively high potential to sorb to sludge, a screening assessment of potential exposure to ecological organisms as a result of biosolids use and disposal would be performed.

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

- making? If the data show that removal of the chemical during wastewater treatment is negligible, then the risk assessments for this chemical would reflect the magnitude of potential ris k derived from this chemical’s negligible removal . The risk assessment may result in the Agency requiring label restrictions that would be necessary for the products to meet the “no unreasonable adverse effects” requirements of FIFRA (e.g., changes to the directions for disposal).

In addition, EPA is required by section 7(a)(2) of the ESA to ensure that any action it authorizes or takes “...is not likely to jeopardize the continued existence of any endangered or threatened species or result in the destructi on or adverse modification of critical habitat” and to use the best scientific data available” in carrying out this obligation. The data EPA intends to call in are necessary to inform the determination required by the ESA as to whether continued registrat ion of a pesticide is not likely to jeopardize the species or its critical habitat. Absent this data EPA may not be able to conclude that this pesticide will not harm endangered species and may therefore need to consider other limitations on the use of th e pesticide in order to fulfill the Agency’s statutory obligations under the ESA. The lack of these data will limit the flexibility that the Agency and registrants have in coming into compliance with the ESA and could result in

### Page 14 of 28 use restrictions which are unnecessarily severe.

Study Title: Sediment and Soil Adsorption/Desorption Guideline Number 835.12 3 0 Test Substance: TGAI Rationale for Requiring the Data A partition (or distribution) coefficient, K d , is needed to conduct the environmental fate assessment to support the MBT uses in pulp and papermill process water systems, recirculating water cooling systems, and oil and gas well production development process systems, metalworking fluid and wood pres ervatives. 

### T he data is not currently available. The Agency has a limited understanding of the potential for MBT to partition and disperse in the aquatic environment by means of sorption to geological materials (e.g., soil, sediments, organic or biologica l matter) . A leaching adsorption/desorption study is needed in order to determine the K d , which will allow the Agency to determine whether it will be tightly bound to sediments, which in turn will allow the Agency to understand the magnitude of MBT exposu re to sediment dwelling organisms.

Controlled environmental fate and transport laboratory studies are used to determine the persistence, mobility, and bioconcentration potential of a pesticide active ingredient and its major degrad at es. The studies offer information on how, or by what mechanism, the pesticide degrades or dissipates, the rate at which it degrades or dissipates, where it goes, and what transformation products are formed. Practical Utility of the Data 1. How will the data be used? The data would establish the significance of partitioning of MBT and its major degradates to sediment as a route of transport and dispersion. The data would also help establish the K d , the partitioning of MBT between soil and water in water/ sediment systems. The K d d ata from the adsorption/desorp tion study are used as inputs to exposure models. These models estimate the expected environmental concentrations of the pesticide and it ’ s degradates under various environmental and use conditions for drinking water and ecological risk assessments. The requested data will result in better characterization of MBT mobility and will allow refined exposure estimates for drinking water and ecological risk assessments.

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

- making? In the absence of acceptable quantitative partitioning data, conservative assumptions about the pesticide’s sorption will be used. For the purposes of aquatic water column exposure modeling, MBT will be assumed to be highly mobile, which will lead to conservative aquatic exposure estimates that may result in unnecessary mitigation. For sediment exposure modeling, MBT will be assumed to partition primarily to sediment, which will lead to conserva tive sediment exposure estimates. If a direct measure of the partition coefficient were available, it would be used as an input for aquatic /sediment modeling which would provide refined aquatic /sediment exposure estimates, allowing for more accurate asses sments of potential risks in drinking water and to ecological receptors, including endangered species.



### Guideline Number: 835.2240 Study Title: Photodegradation in water Practical Utility of the Data 1) What is the value of the study?

### Page 15 of 28 Guideline Number: 835.2240 Study Title: Photodegradation in water Biocides introduced into aqueous systems in the environment can undergo photolytic transformation by sunlight. Results from the photolysis study will indicate the stability and persistence of MBT and potential degradates in an aquatic environment when exp osed to sunlight. The Agency will evaluate the potential risks of concern.

2) How would the data be used? The data would establish the significance of chemical photolysis as a route for degradation and identify, if possible, the photolytic degradation pr oducts formed that may adversely affect non

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

- life of MBT and possibly degradates, and assist in developing a degradation pathway.

3) How could the data affect the risk assessment? The results of photolysis data would indicate if MBT is persistent or if it degrades into degradation products that may adversely affect nontarget organisms and may contaminate their food. The results of the photolysis data would expand the understanding of the results of the hydrolysis data since environmental aquatic conditions usually involve exposure to sunlight.

4) What is triggering the need for this data? Aqueous photodegradation data is needed to conduct the environmental fate assessment to support material preservative and industrial slimicide uses in pulp and papermill process water systems and recirculating water cooling tower systems for MBT

. Also data are needed in order to conduct an environmental fate assessment for outdoor wood preservative use pattern of MBT.

Study Ti tle: Aerobic Aquatic Metabolism Guideline Number: 835.4300 Test Substance: TGAI Rationale for Requiring the Data Aerobic aquatic metabolism data is needed to conduct the environmental fate assessment to support the MBT uses in pulp and papermill process water systems, recirculating water cooling systems, and oil and gas well production development process systems, m etalworking and wood preservatives. Acceptable data on the aerobic aquatic metabolism of MBT in two

- sediment systems are required. The data is not currently available. The Agency has limited understanding of how MBT behaves in aerobic aquatic environment s after discharge to receiving water. The purpose of aerobic aquatic metabolism study is to determine the nature and extent of microbial degradation under aerobic conditions in receiving water/sediment systems during the dispersal of the biocide throughou t the aquatic environment, and to characterize the formation and decline of degradates. This information will determine the persistence and concentrations of MBT and potential degradates over the time in representative aerobic water/sediment systems. The results of the study will indicate the potential for MBT to contaminate the aquatic environment since biocide residues may be taken up by the sediment biota and passed on to other parts of the aquatic food web. Data are needed for two sediment

- water syst ems conducted (one each) at neutral and acidic pHs.

### Page 16 of 28 Practical Utility of the Data 1. How will the data be used? The data would establish the significance of aerobic aquatic microbial degradation of MBT as a route of degradation and identify, if possible, the degradation products formed that may adversely affect non

- target organisms and may contaminate water and food sources of aquatic organisms. The data would also help establish the aerobic aquatic aerobic half

- l ife of MBT in water/sediment systems, and possibly it’s degradates, and assist in developing a degradation pathway.

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

- making? The results of this study would indicate the nature and extent of format ion and decline under aerobic aquatic conditions of MBT and it’s degradates that may be taken up by sediment biota and passed on to other parts of the aquatic food web, and facilitates assessment of potential disposal problems. The study helps to determin e the degradation rate (half

- life) of MBT in the presence of microorganisms in different natural water/sediment systems and establishes what metabolites (degradates) are formed under aerobic (oxygen

- rich) conditions in the laboratory. If we do not receive this data MBT would be assumed to be stable to aerobic metabolism and we would not know if the chemical breaks down leading to reduced risk to human health or the environment or we would not know if more toxic degradates are formed leading to increased ri sk to human health or the environment.

### Page 17 of 28 Study Ti tle: Anaerobic Aquatic Metabolism Guideline Number: 835.4400 Test Substance: TGAI Rationale for Requiring the Data Anaerobic aquatic metabolism data is needed to conduct the environmental fate assessment to support the MBT uses in pulp and papermill process water systems, recirculating water cooling systems, and oil and gas well production development process systems, metalworking fluids and wood preservatives systems. Acceptable data on the anaerobic aquatic metabolism of MBT in two

- sediment systems are required. The data is not currently available. The Agency has limited understanding of how MBT behaves in anaerob ic aquatic environments after discharge to receiving water. The purpose of an anaerobic aquatic metabolism study is to determine the nature and extent of microbial degradation under anaerobic conditions in water/sediment systems during the dispersal of th e biocide throughout the aquatic environment, and to characterize the formation and decline of degradates. This information will determine the persistence and concentrations of MBT and potential degradates over time in representative anaerobic water/sedim ent systems. The results of the study will indicate the potential for MBT to contaminate the aquatic environment since biocide residues may be taken up by the sediment biota and passed on to other parts of the aquatic food web. Additionally, anaerobic co nditions are more likely to prevail where biocides are found in aquatic environments than in strictly terrestrial environments. Data are needed for two sediment

water systems conducted (one each) at neutral and acidic pHs.

Practical Utility of the Data 1. How will t he data be used? Anaerobic aquatic metabolism data will facilitate a better understanding of the fate of MBT residues in water and sediment. The data would establish the significance of an aerobic aquatic microbial degradation of MBT as a route of degradation and identify, if possible, the degradation products formed that may adversely affect non

- target organisms and may contaminate water and food sources of aquatic organisms. The data would also help establish the an aerobic aqua tic m icrobial half

- life of MBT in water/sediment systems, and possibly it’s degradates, and assist in developing a degradation pathway.

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

- making? The results of this study would indicate the nature and e xtent of formation and decline under anaerobic aquatic conditions of MBT and it’s degradates that may be taken up by sediment biota and passed on to other parts of the aquatic food web, and would facilitate assessment of potential disposal problems. The

s tudy helps to determine the degradation rate (half

- life) of MBT in the presence of microorganisms in different natural water/sediment systems and establishes what metabolites (degradates) are formed under anaerobic (oxygen

- poor) conditions in the laborator y

. If the data indicate that degradation in anaerobic conditions occurs rapidly in acidic and or neutral aquatic systems and produces nontoxic transformations products, then the A gency could potentially determine that MBT residues of concerns do not persi st in these systems. If data indicate that degradation is not appreciable in aquatic systems or that transformation products are similar or higher toxicity than the parent compound, then the Agency could conclude that MBT residues of concern persist in aq uatic systems under anaerobic conditions. In the absence of the requested data, MBT anaerobic aquatic metabolism half

- lives will be conservatively assumed to be stable across the environmental pH range

.

### Page 18 of 28 Study Titles: Ready Biodegradability; Porous Pot Test; or Simulation Test

– Aerobic Sewage Treatment: A. Activated Sludge Units; or Simulation Tests to Assess the Biodegradability of Chemicals Discharged to Wastewater (particularly Biod egradation in Activated Sludge) Guideline Numbers: 835.31 10; 835.3220; 835.3240; or 835.3280 , respectively Test Substance: TGAI Rationale for Requiring the Data For antimicrobial chemicals that go down

- the

- drain and reach a WWTP, as part of its screening

- level environmental fate assessment, EPA will analyze the potential impact of the antimicrobial chemical on the microorganisms in the biological treatment processes of a WWTP. Biodegradation is an important environmental pathway in which the antimicrobial is broken down by bacteria. These study results supply information on the rate of biological breakdown and the completeness of the degradation to carbon dioxide and water. A Ready Biodegradability study would allow the Agency to determine whether or not the chemical achieves ‘‘pass levels’’ for ready biodegra dability (e.g., 70% removal of dissolved organic carbon). The results of the Activated Sludge Respiration Inhibition Test (ASRI) determine which of these four biodegradation tests are required. If the ASRI test EC 50 is less than or equal to 20 mg/L, then either the (i) Biodegradation in Activated Sludge Study or (ii) Simulation Test

– Aerobic Sewage Treatment: A. Activated Sludge Units or the (iii) Porous Pot Test is required. If the ASRI test EC 50 is greater than 20 mg/L, then the applicant must choose e ither: (i) Ready Biodegradability or (ii) Biodegradation in Activated Sludge or (iii) Simulation Test

– Aerobic Sewage Treatment: A. Activated Sludge Units or (iv) the Porous Pot Test. If the antimicrobial passes the Ready Biodegradability study, then no further testing is required. If, however, the antimicrobial fails the Ready Biodegradability study, then the (i) Biodegradation in Activated Sludge or (ii) Simulation Test

– Aerobic Sewage Treatment: A. Activated Sludge Units, or (iii) the Porous Pot stud y is required. Practical Utility of the Data 1. How will the data be used? The data from a biodegradation study will be used to determine the percent removal of the antimicrobial as a result of biodegradation of the antimicrobial by activated sludge microorganisms. Percent removal via biodegradation is a key input used to determine concentrations of the antimicrobial in surface water immediately downstream of wastewater treatment plants. The concentrations of antimicrobial pesticide immediately down stream of wastewater treatment plants are used to assess exposure and risk to non

target endangered and non

- endangered species. Exposure data are integral parts of the risk equation for determining the impact of pesticides to beneficial non

- target organis ms through direct exposure from their food sources and habitat.

In addition, the data will be used to determine whether or not additional studies and/or label restrictions are needed. If the chemical does not achieve a ‘‘pass level’’ for ready biodegrada bility, then the Agency would determine that the chemical has the potential to pass through the WWTP and therefore may be discharged in to the aquatic environment potentially resulting in exposure to non

- target species. This determination would trigger fu rther data requirements to assess the chemical’s impact on the aquatic environment upon release.

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

- making? If the chemical is found to be readily biodegraded, then activated sludge microorganisms would be identified as highly biodegradable (90% removal via biodegradation). This result would be used in conjunction with wastewater treatment plant influent volume and measurement endpoints for aquatic organisms to determine concentrations of antimicro bial pesticide downstream of wastewater treatment plants. If high inhibition of activated sludge microorganisms (i.e., EC 50 less than or equal to 20 mg/L) is determined in an activated sludge respiration inhibition test, then higher

- tiered wastewater trea tment plant (WWTP) biodegradation studies and/or an activated sludge sorption isotherm study may be triggered. If results of higher

- tier WWTP biodegradation tests indicate low or negligible removal by biodegradation,

### Page 19 of 28 the risk assessments for this chemical would reflect the magnitude of potential risk derived from the chemical’s lack of biodegradability. The risk assessment may result in the Agency requiring label restrictions that would be necessary for the products to meet the “no unreasonable adverse ef fects” requirements of FIFRA (e.g., changes to the directions for disposal).

In addition, EPA is required by section 7(a)(2) of the ESA to ensure that any action it authorizes or takes “...is not likely to jeopardize the continued existence of any endangere d or threatened species or result in the destruction or adverse modification of critical habitat” and to use the best scientific data available” in carrying out this obligation. The data EPA intends to call in are necessary to inform the determination
req uired by the ESA as to whether continued registration of a pesticide is not likely to jeopardize the species or its critical habitat. Absent this data EPA may not be able to conclude that this pesticide will not harm endangered species and may therefore n eed to consider other limitations on the use of the pesticide in order to fulfill the Agency’s statutory obligations under the ESA. The lack of these data will limit the flexibility that the Agency and registrants have in coming into compliance with the E SA and could result in use restrictions which are unnecessarily severe.

### Page 20 of 28 

## Appendix B: Ecological Guideline Study Justifications

Study Title: Fish Early

- life Stage Toxicity Test (freshwater species) Guideline Number: 850.1400 Test Substance: TGAI Rationale for Requiring the Data

No fish early

- life stage toxicity test for MBT has been submitted. The fish early

- life stage toxicity test provides the leth al and sublethal effects of a test substance on fish species. The study is necessary for MBT because the pesticide use patterns and environmental fate characteristics are expected to result in repeated exp osure of freshwater organisms. Without these data, the Agency is unable to evaluate the potential risks to freshwater fish and aquatic

- phas e amphibians (for which fish serve as surrogates) associated with chronic exposure to MBT

. If the test is not conducted with the most acutely sensitive species, an acute toxicity test for the species used in the early life stage test needs to be conducted to allow calculation of an acute

- to

- chronic ratio for use in predicting an early life stage result for the most acutely sensitive species. Practical Utility of the Data

1. How will the data be used? The data from the fish early life stage test will be used to estimate the chronic risks to freshwater fish and amphibians associated with chronic exposures to MBT. The data will reduce uncertainties associated with pot ential risks to freshwater fish and a mphibians thereby facilitating sound environmental management of natural resources, particularly, freshwater fisheries.

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

- making? In the absence of data, chronic risks would be presumed to freshwater fish/amphibians under chronic exposure conditions. T he lack of these data will limit the flexibility the Agency and registrants have in addressing risks to non

- listed and listed species and in coming into compliance with the Endang ered Species Act, and could result in use restrictions or withdrawl of uses for MBT which may otherwise be avoided, or which are unnecessarily severe.

Study Title: Aquatic plant growth, floating vascular species ( Lemna sp. ), Tier II Guideline Number: 850.4 400 Test Substance: TGAI Rationale for Requiring the Data
No non

- rooted vascular aquatic plant toxicity data ha s been submitted for MBT. U se s of MBT in industrial process and water systems and discharges from oil and gas well development are expected to lead to exposure of aquatic organisms due to the repeated release and transport of MBT from use sites into aquatic ecosystems, and the persistence of MBT. Without these data, the Agency is unable to evaluate the potential risks to non

- rooted vascular aquatic plants associated with exposure to MBT

. Practical Utility of the Data 1. How will the data be used? Mats of floating non

- rooted aquatic plants provide habitat for small invertebrates, food and shelter for fish and amphibians, and food for waterfowl and marsh birds. The floating vascular aquatic plant study would allow the Agency to evaluate effects to a critical component of the structure and function of the aquatic plant community. A toxicity study on a non

- roote d vascular aquatic plant species is used to establish a dose response relationship of MBT with effects to non

- rooted aquatic plants in terms of yield, growth

### Page 21 of 28 rate, and area under the growth curve . The effects data would be used to determine the likelihood that losses to non

- rooted aquatic vascular plants will occur and that such losses would indirectly lead to loss of other aquatic organisms through impacts such as loss of a food resource, habitat, or habitat quality

.

2. How could the data impact the Agency's future decision

- making?
Because this is the only member of the 

### quaternary phosphonium class of antimicrobials currently registered in the U.S., there is no possibility of using submitted toxicity data from closely

- related surrogate chemicals to fi ll in potential data gaps. Therefore, until additional data become available, risks

to non

- rooted vascular plants (both Federally

- listed and non

- listed species) will be assumed in future MBT risk assessments. T he lack of these data will limit the flexibi lity the Agency and registrants have in addressing risks to non

- listed and listed species and in coming into compliance with the Endangered Species Act, and could result in use restrictions or withdrawl of uses for MBT which may otherwise be avoided, or which are unnecessarily severe.

Study Title: Aquatic plant growth, non

- vascular species (one freshwater green alga species, one freshwater diatom species, one estuarine/marine species, and one cyanobacterium specie s ), Tier II Guideline Number: 850.5400 Test Substance: TGAI Rationale for Requiring the Data
No nonvascular aquatic plant toxicity data ha s been submitted for MBT. A battery of four species, representing different morphological characteristics and environmental habitats are required for use patterns resulting in emissions to surface waters. U se s of MBT in industrial process and water systems and discharges from oil and gas well development, recirculating cooling tower, metalworking and wood
preserv atives are expected to lead to exposure of aquatic organisms due to the repeated release and transport of MBT from use sites into aquatic ecosystems, and the persistence of MBT. For MBT, there is evidence in the open literature that effects to algal speci es may occur at or below levels resulting on impacts to microbes. Without these data, the Agency is unable to evaluate the potential risks to non

vascular aquatic plants associated with exposure to MBT

. T he Agenc y would have to presume risk to federally listed and non

- listed non

- vascular plants

, but would not be able to quantify the risk.

Practical Utility of the Data 1. How will the data be used? The four aquatic nonvascular plant studies would allow the Agency to analyze effects on primary production. A toxicity study on non

- vascular aquatic plant species is used to establish a dose response relationship of MBT with primary productivity in terms of yield, growth rate, and area under the growth

curve . The effects data would be u sed to determine the likelihood that losses to primary production will occur and that such losses would indirectly lead to loss of other aquatic organisms through impacts such as loss of a food resource, habitat, or habitat quality

.

2. How could the dat a impact the Agency's future decision

- making?
Because this is the only member of the 

### quaternary phosphonium class of antimicrobials currently registered in the U.S., there is no possibility of using submitted toxicity data from closely

- related surrogate ch emicals to fill in potential data gaps. Therefore, until additional data become available, risks to aquatic non

- vascular plants (both Federally

- listed and non

- listed species) will be assumed in future MBT risk assessments. T he lack of these data will lim it the flexibility the Agency and registrants have in addressing risks to non

- listed and listed species and in coming into compliance with the Endangered Species Act, and could result in use restrictions or withdrawl of uses for MBT which may otherwise be avoided, or which are unnecessarily severe.

### Page 22 of 28 Study Title: Modified Activated Sludge, Respiration Inhibition Test for Sparingly Soluble Chemicals or Activated Sludge Respiration Inhibition Test Guideline Number: 850.6800 or OECD 2 09 , respectively Test Substance: TGAI Rationale for Requiring the Data An activated sludge, respiration inhibition test (ASRI) is needed to identify whether this pesticide could harm activated sludge microorganisms found in biological wastewater treatment systems. The Agency will use these data to determine the potential imp act of this chemical on waste water treatment plants (WWTPs) as a result of respiration inhibition of activated sludge microorganisms. This test is also necessary to enable EPA to establish correct concentrations for use in the biodegradability test, if th at test is determined to be adequate for assessing biodegradation potential. Furthermore, the results of the Activated Sludge Respiration Inhibition Test (ASRI) determine which biodegradation test is required. If the ASRI test EC 50 is less than or equal t o 20 mg/L, then either the Biodegradation in Activated Sludge Study or the Porous Pot Test is required. If the ASRI test EC 50 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 Po rous Pot study is required.

Practical Utility of the Data 1. How will the data be used? The data will be used to assess potential adverse effects to activated sludge microorganisms. In addition, the data will be used to determine whether or not label restrictions are needed. The study will identify the inhibitory effect of this chemical on the treatment plant’s microorganisms’ respiration at different concentrations of the test substance and will identify the EC 50 , the effective concentration of the t est substance at which the respiration rate is 50% of that shown by the control under conditions in this guideline. The data will also determine suitable non

- inhibitory concentrations to be used in biodegradability tests.

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

- making? If the data indicate a high degree of activated sludge respiration inhibition, a more rigorous test for biodegradation in wastewater treatment will be required than the ready biodegradability test. Also, if a high degree of respiration inhibition is demonstrated and biodegradation and/or sorption is indicated to be negligible, the Agency may require label restrictions or mitigation measures to insure that activated sludge microorganisms will not be adversely impacted.



### G uideline Number: 850.1735 Study Title: Sediment acute toxicity test, freshwater invertebrate Practical Utility of the Data 1) What is the value of the study? MBT may tend to accumulate in sediments over time and pose risks to sediment

- dwelling organisms in freshwater environments.

2) How would the data be used? Reported endpoints such as survival, growth, and/or emergence are compared to estimated sediment concentrations to determine the potential for risk.

3) How could the data affect the risk assessment?

### Page 23 of 28 G uideline Number: 850.1735 Study Title: Sediment acute toxicity test, freshwater invertebrate Practical Utility of the Data Exceedance of the LOC indicate s a potential for risk to sediment

- dwelling organisms that may warrant regulatory action to mitigate risk

.
4) What is triggering the need for this data? U se s of MBT as a wood preservative and in industrial process es and water systems may lead to acute exposure of aquatic organisms due to transport of the active ingredient into aquatic sediments.



### Guideline Number: 850.1740 Study Title: Sediment acute toxicity test, marine invertebrate Practical Utility of the Data 1) What is the value of the study? MBT may tend to accumulate in sediments over time and pose risks to sediment

- dwelling organisms in estuarine/marine environments.

2) How would the data be used? Reported endpoints such as survival, growth, and/or emergence are compared to estimated sediment concentrations to determine the potential for risk.

3) How could the data affect the risk assessment? Exceedance of the LOC indicate s a potential for risk to sediment

- dwelling organisms that may warrant regulatory action to mitigate risk

.
4) What is triggering the need for this data? U se s of MBT as a wood preservative and in industrial processes and water systems may lead to acute exposure of aquatic organisms due to transport of the ac tive ingredient into aquatic sediments.

Study Title: Test Method: 100.5 Life

- cycle Test for Measuring the Effects of Sediment

- associated Contaminants on Chironomus dilutus (formerly known as C. tentans ) Guideline Number: Agency

- wide guideline USEPA 2000b ; Non

- 850 guideline , Special Study Exposure Method: Spiked whole sediment Test Substance: TGAI Rationale for Requiring the Data No chronic spiked

- sediment toxicity test for a freshwater benthic emergent insect ha s been submitted for MBT. Use of MBT in industrial processes and water systems and oil and gas well production systems

, recirculating cooling towers, metalworking fluids and wood preservatives may result in the active ingredient reaching aquatic sediments. Sediment bent hos may be exposed to s ediment associated chemicals via pathways not accounted for in water only studies , such as ingestion of sediment

. Chemicals that partition to sediment and are persistent in the sediment have the potential to pose a chronic risk to

se diment benthos. MBT or its degradates are assumed to partition to sediment and be persistent in aquatic environments

.
For freshwater sediment studies, chronic tests on a benthic emergent insect ( Chironomus dilutes, formerly Chironomus tentans ) and an amphipod ( Hyalella azteca ) are requested. Although both are freshwater species, Hyalella and Chironomus differ substantially in their ecological niche ( i.e ., infaunal species versus epibenthic), physiology, and potential sensitivities to MBT expos ure. Prior to conduct of the

### Page 24 of 28 study, the test design and protocol must be submitted for Agency review and approval. If the half

- life is found to be <10 days in both aerobic and anaerobic aquatic sediment metabolism studies a 10

- day survival and growth stu dy for this species using public draft 850.1735 Whole Sediment Acute Toxicity Invertebrates, Freshwater. Prior to conduct of the study, the test design and protocol must be submitted for Agency review and approval as the there are changes in recommended t esting guidance from that provided in the public draft. Practical Utility of the Data 1. How will the data be used? Data from sediment toxicity studies will be used to estimate potential risks to benthic organisms associated with uses of MBT. Data from sediment toxicity studies will be compared to estimated sediment chronic exposure concentrations to evaluate the potential for MBT to adversely impact survival, emergence, reproduction, and growth of sediment invertebrates.

2. How could the data impact t he Agency’s future decision

- making? If the data indicates that registered MBT usage may pose a risk of adverse effects to non

- target benthic organisms above the Agency Level of Concern, the Agency may explore decision options to mitigate this risk. T he l ack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act, and could result in use restrictions for MBT which may otherwise be avoided, or which are unnecessarily severe.

Study Title: Methods for Assessing the Chronic Toxicity of Marine and Estuarine Sediment

Associated Contaminants with the Amphipod Leptocheirus plumulosus Guideline Number: Agency

- wide guideline USEPA 2001c; Non

- 850 guideline , Special Study Exposure Method : Spiked whole sediment Test Substance: Pure active ingredient Rationale for Requiring the Data No chronic spiked

- sediment toxicity test for an estuarine/marine benthic amphipod ha s been submitted for MBT. Use of MBT in industrial processes and water systems and oil and gas well production systems may result in the active ingredient reaching aquatic estuarine/marine sediments. Sediment benthos may be exposed to s ediment associated chemicals via pathways not accounted for in water only studies , such

as ingestion of sediment

. Chemicals that partition to sediment and are persistent in the sediment have the potential to pose a chronic risk to sediment benthos. MBT and its degradates are assumed to partition to sediment and be persistent given the lack of aquatic fate information.

Prior to conduct of the study, the test design and protocol must be submitted for Agency review and approval. If the half

- life is found to be <10 days in both aerobic and anaerobic aquatic sediment metabolism studies a 10

- day su rvival and growth study for this species using public draft 850.1740 Whole Sediment Acute Toxicity Invertebrates, Freshwater. Prior to conduct of the study, the test design and protocol must be submitted for Agency review and approval as the there are cha nges in recommended testing guidance from that provided in the public draft. Practical Utility of the Data 1. How will the data be used? Data from sediment toxicity studies will be used to estimate potential risks to benthic organisms associated with uses of MBT. Data from sediment toxicity studies will be compared to estimated sediment chronic exposure concentrations to evaluate the poten tial for MBT to adversely impact survival, emergence, reproduction, and growth of sediment invertebrates.

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

- making? If the data indicates that registered MBT usage may pose a risk of adverse effects to non

- target benthic

### Page 25 of 28 organisms above the Agency Level of Concern, the Agency may explore decision options to mitigate this risk. T he lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endange red Species Act, and could result in use restrictions for MBT which may otherwise be avoided, or which are unnecessarily severe.



### Guideline Number: 850. 3020 Study Title: Honeybee acute contact Practical Utility of the Data 1) What is the value of the study? This study will be used to determine lethal effects to honeybees from acute exposure to MBT.

2) How would the data be used? The LD 50 is used to categorize acute toxicity of MBT to insect pollinators.

3) How could the data affect the risk assessment? Categorization of the toxicity level indicates the need for product labels to bear a precautionary statement for insect pollinators.

4) What is triggering the need for this data? U se s of MBT as a wood preservative may lead to acute exposure of honeybees that contact wood treated with MBT.



### Guideline Number: 850. 3030 Study Title: Toxicity of residues to honeybees Practical Utility of the Data 1) What is the value of the study? This study will be used to assess honeybee mortality from exposure to wood treated with MBT.

2) How would the data be used? Measurement endpoints for lethality are compared to exposure estimates to evaluate the potential for risk.

3) How could the data affect the risk assessment? Mortality of honeybees from exposure to wood treated with MBT may warrant regulatory action to mitigate risk to insect pollinators

.
4) What is triggering the need for this data? U se s of MBT as a wood preservative may l ead to acute exposure of honeybees that contact wood treated with MBT.

### Page 26 of 28 

## Appendix C:

Table 1. Registered Products of MBT Registration No. Registration Name Company Name Formulation Type % of Active Ingredient

1022

- 583 NEXGEN IBC Manufacturing Co. Emulsifiable Concentrate 14.7

1448

- 34 MTC

- 10 Buckman Laboratories Inc. Ready

- to

- Use Solution 10

1448

- 80 METHYLENE BIS(THIOCYANATE) Buckman Laboratories Inc. Technical Chemical 99

1448

- 81 BUSAN 1009 Buckman Laboratories Inc. Ready

- to

- Use Solution 10

1448

- 102 BUSAN 1071 Buckman Laboratories Inc. Soluble Concentrate 2.5

1448

- 147 M

- 20

- 1 Buckman Laboratories Inc. Ready

- to

- Use Solution 10

1448

- 148 M

- 20

- 2 Buckman Laboratories Inc. Soluble Concentrate 10

1448

- 171 M

- 5

- 1 Buckman Laboratories Inc. Ready

- to

- Use Solution 2.5

1448

- 172 M

- 5

- 2 Buckman Laboratories Inc. Soluble Concentrate 2.5

1448

- 357 MTC

- 10

- SR Buckman Laboratories Inc. Ready

- to

- Use Solution 10

1448

- 358 MTC

- 10

- CT Buckman Laboratories Inc. Ready

- to

- Use Solution 10

1448

- 359 MTC

- 10WB

- CT Buckman Laboratories Inc. Ready

- to

- Use Solution 10

1448

- 360 MTC

- 10WB

- SR Buckman Laboratories Inc. Ready

- to

- Use Solution 10

1448

- 375 MECT

- F Buckman Laboratories Inc. Formulation Intermediate 10

1448

- 376 BUSAN 1071WB Buckman Laboratories Inc. Wettable Powder 2.5

1448

- 377 BUSAN 1009 WB Buckman Laboratories Inc. Ready

- to

- Use Solution 10

### Page 27 of 28 Registration No. Registration Name Company Name Formulation Type % of Active Ingredient

1448

- 408 BUSAN 1350 Buckman Laboratories Inc. Wettable Powder 8

1448

- 435 BUSAN 1265WB Buckman Laboratories Inc. Soluble Concentrate/ Solid 10

1448

- 438 BUSAN 1223 Buckman Laboratories Inc. Emulsifiable Concentrate 10

1448

- 439 BUSAN 1234 Buckman Laboratories Inc. Soluble Concentrate 10

1706

- 112 NALCON 7619 Nalco Company Ready

- to

- Use Solution 10

1706

- 200 NALCON 10WB Nalco Company Ready

- to

- Use Solution 10

3876

- 121 GE BETZ SLIMICIDE C

31 GE Betz, Inc. Ready

- to

- Use Solution 5

8622

- 42 METHYLENE BIS (THIOCYANATE) ICL

- IP America, Inc. Technical Chemical 99

9386

- 4 AMA

- 10 Kemira Chemicals, Inc. Ready

- to

- Use Solution 10

9386

- 12 THIONATE Kemira Chemicals, Inc. Technical Chemical 99

9386

- 26 AMA

- 10S Kemira Chemicals, Inc. Ready

- to

- Use Solution 10

9386

- 31 AMA

- 10W Kemira Chemicals, Inc. Ready

- to

- Use Solution 10

33677

- 1 TOLCIDE(R) MBT Rhodia UK Limited Technical Chemical 99

47091

- 12 SM

- 10P INDUSTRIAL MICROBIOCIDE Aurora Specialty Chemistries Ready

- to

- Use Solution 10

56156

- 1 X

- 100 NATURAL SEAL WOOD PRESERVATIVE American Building Restoration Products Inc Ready

- to

- Use Solution .5

62190

- 30 ANTIBLU MC

- 30 Arch Wood Protection, Inc. Emulsifiable Concentrate 14.7

64715

- 1 VEDEXIL

- DM/K Lamirsa Technical 98.95

### Page 28 of 28 Registration No. Registration Name Company Name Formulation Type % of Active Ingredient

Laboratorie s Miret S.A. Chemical

67869

- 17 N

- 948 TECHNICAL Verichem, Inc. Technical Chemical 99

67869

- 31 N

- 948 WB Verichem, Inc. Soluble Concentrate/ Solid 10

73612

- 1 SENTRY Chemcolour Industries (NZ) Ltd. Soluble Concentrate 6.42

74655

- 4 SPECTRUM RX

- 32 Hercules Incorporated Ready

- to

- Use Solution 7

74655

- 6 SPECTRUM RX

- 38 Hercules Incorporated Ready

- to

- Use Solution 5

74655

- 7 SPECTRUM RX

- 31 Hercules Incorporated Ready

- to

- Use Solution 5

84377

- 1 BELLICIDE Bell Performance Inc Flowable Concentrate 2.5