United States Chemical Safety June 2012 

Environmental Protection and Pollution Prevention 

Agency (7510P) 

 

Methylene Bis(Thiocyanate) 

Registration Review: 

Final Work Plan 

June 2012 

 
Docket Number: EPA-HQ-OPP-20II-0613 

www.regulations.gov 

Methylene Bis(Thiocyanate) 

Registration Review: 

Final Work Plan 

June 2012 

Case # 2415 

Approved By: 

oan Harrigan- arrelly 

Director, Antimicrobials Division 

Date: 

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Docket Number: EPA-HQ-OPP-2011-0613 

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Methylene Bis(Thiocyanate) Registration Review Team

Human Health & Environmental Effects

Nathan Mottl 

Steven Malish 

Jonathan Chen 

Srinivas Gowda 

Najm Shamim 

William Erickson 

Risk Management

Rebecca von dem Hagen 

Lance Wormell 

Office of General Counsel

Philip Ross 

________________________________________ 

Supporting documents for the Methylene Bis(Thiocyanate) Case may be found in the registration 

review docket EPA-HQ-OPP-2011-0613 located on the internet at www.regulations.gov. 
Docket Number: EPA-HQ-OPP-2011-0613 

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Introduction

This is the Final Work Plan (FWP) of the Environmental Protection Agency (EPA or “the 

Agency”) for the registration review of methylene bis(thiocyanate) (Case 2415). The work plan 

includes the expected registration review timeline. The work plan also addresses public 

comments received concerning the Preliminary Work Plan (PWP) in the Summary Document 

which was posted in the methylene bis(thiocyanate) registration review docket, and any other 

comments concerning the initial docket postings. The Summary Document provided information 

on what EPA knows about the pesticide and what additional risk analyses and data or 

information the Agency believes are needed to make a registration review decision. 

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. Changes in science, public policy and pesticide use practices will occur over time. 

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 that 

statutory standard. The public phase of registration review begins when the initial docket is 

opened for each case. Information on this program is provided at: 

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

The Methylene Bis(Thiocyanate) Case (Case Number 2415) includes one active ingredient, PC 

Code 068102. The first product containing methylene bis(thiocyanate) (MBT) as an active 

ingredient was registered in the United States in 1949. Currently, there are 40 MBT products 

registered with EPA. Products containing MBT are registered for use as material preservatives 

for incorporation into products such as adhesives, coatings, fuels, metalworking cutting fluids, 

textiles, plastic products, resin emulsions, paints, paper products and various other products. 

Products containing MBT are also registered as microbiocides for use in pulp/paper mills, 

cooling water systems (recirculating), oil field operations, air washer systems, brewery 

pateurizers, hydrotesting, leather processing and industrial water supply systems. MBTcontaining products are also registered for use as wood preservatives. 

No tolerances or exemptions from tolerances have been established for MBT. MBT is cleared as 

an indirect additive in food contact substances for slimicides in paper and paperboards by FDA 

(29 CFR 176.300). Also, FDA has cleared the use of MBT in adhesives under a threshold of 

regulation; MBT can only be used in packaging materials for dry foods at a level not to exceed 

0.01% active ingredient (21 CFR 170.39). 

The Agency completed a Reregistration Eligibility Decision (RED) for methylene 

(bis)thiocyanate in 1997. At the time of the RED, the Agency was unable to make a 

reregistration decision on MBT’s use as a wood preservative, in leather processing liquid and 

products and in paint due to the lack of data. The Agency has since received the 90-day 

inhalation study (MRID 45366301) and intends to incorporate it in the anticipated risk 

assessments for the registration review of MBT. 
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The methylene (bis)thiocyanate PWP was published on December 21, 2011 and the 60-day 

comment period ended on February 21, 2012. The PWP and supporting documents are available 

on www.regulations.gov docket number EPA-HQ-OPP-2011-0613. 

Comments Received on the Preliminary Work Plan

The Agency received no comments during the public comment period on the initial docket. In 

the PWP, the Agency solicited comments on specific topics: environmental justice, water body 

impairment, trade irritants, and structure activity relationships. No comments or information 

were received during the public comment period concerning these issues. 

Therefore, the data needs, work plan, and timeline described in the PWP remain as they were 

presented initially. Further, this document makes final the work plan for the methylene 

bis(thiocyanate) registration review process. 

Risk Assessments and Anticipated Data Needs

The Agency anticipates the need to conduct a comprehensive ecological risk assessment, 

including an endangered species risk assessment, for all uses of methylene (bis)thiocyanate. The 

Agency also anticipates the need to conduct a human health risk assessment. The Agency 

anticipates needing additional data for use in conducting the registration review for MBT. 

Ecological Risk: 

 A quantitative ecological risk assessment was not performed for MBT at the time of the 

RED. For registration review, the Agency anticipates the need to conduct a 

comprehensive ecological risk assessment for MBT, including an endangered species 

assessment. 

 The Agency anticipates the need to require the following additional ecological data for 

use in the registration review of methylene (bis)thiocyanate. 

850.1400 -- Fish early-life stage toxicity test (freshwater) 

850.4400 -- Aquatic plant toxicology test using Lemna spp., Tier I 

850.5400 -- Algal Toxicity Tier I and Tier II 

850.3020 -- Honey bee acute contact toxicity 

850.3030 -- Honey bee toxicity of residues on foliage 

850.1735 -- Whole sediment acute toxicity invertebrates (freshwater)1

850.1740 -- Whole sediment acute toxicity invertebrates (marine)1

Special Study -- Chronic sediment toxicity test (freshwater invertebrate) 1 

 The Agency anticipates the need to require the following additional environmental fate 

data for use in the registration review of methylene (bis)thiocyanate. 

 

1

 If the environmental fate data anticipated as being required for this registration review demonstrate that the halflife of the MBT in the sediment is greater than 10 days and if any one of the following conditions are met (1) Kd 

<50, (2) Koc <1000, or (3) Kow <3, then the registrant may request that the Agency waive the sediment studies. 
Docket Number: EPA-HQ-OPP-2011-0613 

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835.2240 -- Photodegradation in water (at pH 5) 

835.1240 -- Adsorption/desorption 

835.4300 -- Aerobic aquatic metabolism 

835.4400 -- Anaerobic aquatic metabolism 

850.6800 -- Modified activated sludge, respiration inhibition test2

835.3110 -- Ready Biodegradability2

835.3220 -- Porous Pot Test2

835.3280 -- Simulation Tests to Assess the Biodegradability of Chemicals Discharged 

to Wastewater2

835.3240 -- Simulation Test – Aerobic Sewage Treatment: A. Activated Sludge Units2

Special Study -- Leachability of wood preservatives used in contact with water 

 For more information, please refer to Product Chemistry, Environmental Fate, and 

Ecological Effects Scoping Document in Support of Registration Review of Methylene 

bis(thiocyanate), located in the docket. 

Human Health Risk: 

 The most recent human health risk assessments for methylene (bis)thiocyanate were 

completed in 1997, in support of the RED. 

 The Agency anticipates the need to require the following additional human health data 

for use in conducting occupational, residential, dietary and aggregate risk assessments for 

the registration review of methylene (bis)thiocyanate. 

875.1200 -- Dermal indoor exposure 

875.1400 -- Inhalation indoor exposure 

875.1600 -- Application exposure data reporting and calculations 

875.2300 -- Indoor surface residue dissipation 

875.2500 -- Inhalation exposure 

875.2800 -- Description of human activity 

875.2900 -- Data reporting and calculations 

875.1700 -- Product use information (handler) 

875.2700 -- Product use information (postapplication) 

 The Agency anticipates the need to conduct an aggregate risk assessment based on the 

potential for residential, dietary and drinking water exposure. 

 

2

 The results of the Activated Sludge Respiration Inhibition Test (ASRI) that is expected to be required would 

determine which of these three biodegradation tests would be anticipated to be required. If the ASRI test EC50 is 

less than or equal to 20 mg/L, then either the Biodegradation in Activated Sludge Study or Simulation Test – 

Aerobic Sewage Treatment: A. Activated Sludge Units or the Porous Pot Test would be anticipated to be required. 

If the ASRI test EC50 is greater than 20 mg/L, then the applicant would choose to conduct either: (i) Ready 

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

Activated Sludge Units or the Porous Pot Test. If the antimicrobial passes the ready biodegradability study, then no 

further testing would be expected to be required. If, however, the antimicrobial fails the ready biodegradability 

study, then the Biodegradation in Activated Sludge or Simulation Test – Aerobic Sewage Treatment: A. Activated 

Sludge Units, or the Porous Pot study would be expected to be required. 
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 For more information, please refer to Methylene Bis Thiocyanate (MBT): Human Health 

Risk Assessment Scoping Document in Support of Registration Review, located in the 

docket. 

Product Chemistry: 

 The Agency does not anticipate the need to require additional product chemistry data for 

this registration review case at this time. 

 For more information, please refer to Product Chemistry, Environmental Fate, and 

Ecological Effects Scoping Document in Support of Registration Review of Methylene 

bis(thiocyanate), located in the docket. 

Incidents:

Ecological: 

 No methylene (bis)thiocyanate ecological incidents have been reported in the Agency’s 

Ecological Incident Information System (EIIS). 

Human Health: 

 There are nine MBT-specific incidents that have been reported in the Office of Pesticide 

Program Incident Data System (IDS). Most of the incidents were as a result of acute/short 

term inhalation exposure. Workers reported irritation and burning of the lung tissue as well 

as airway and vocal cord dysfunction. Long-term respiratory irritation has been reported in 

workers working with MBT containing products. There have also been skin irritation 

incidents reported. 

Endangered Species 

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

determination for methylene (bis)thiocyanate. The ecological risk assessment planned during 

registration review will allow the Agency to determine whether methylene (bis)thiocyanate’s use 

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. 

Endocrine Disruptor Screening Program 

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

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

taxonomic groups. As part of its 1997 Reregistration Eligibility Decision for MBT decision, 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), 

methylene (bis)thiocyanate is subject to the endocrine screening part of the Endocrine Disruptor 

Screening Program (EDSP). 

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

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

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

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

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

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

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

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

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

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

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

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

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

which contains 58 pesticide active ingredients and 9 inert ingredients. Methylene 

(bis)thiocyanate is 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 methylene 

(bis)thiocyanate. 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/. 

Timeline

EPA has created the following estimated timeline for the completion of the methylene 

bis(thiocyanate) registration review. 

Anticipated Schedule

Activities Estimated Month/Year

Phase 1: Opening the docket 

Open Public Comment Period for Docket December 2011 - 

Completed

Close Public Comment Period for Docket February 2012 - 

Completed 

Phase 2: Case Development 

Develop Final Work Plan (FWP) June 2012 - Completed 

Issue DCI June 2013 

Data Submission June 2015 
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Open Public Comment Period for Preliminary Risk Assessments December 2016 

Close Public Comment Period for Preliminary Risk Assessments January 2017 

Phase 3: Registration Review Decision 

Open Public Comment Period for Proposed Reg. Review Decision June 2017 

Close Public Comment Period for Proposed Reg. Review Decision August 2017 

Final Decision and Begin Post-Decision Follow-up 2017 

Total (years) 6 

Next Steps

A DCI will be developed regarding the data needs listed under the “Risk Assessments and 

Anticipated Data Needs” section of this document. The Agency expects to issue the DCI in June 

2013. The Agency anticipates the need to conduct human health and ecological risk assessments 

for all uses of MBT. 

 
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Summary of Anticipated Data Requirements – Methylene (Bis)Thiocyanate 

The table below summarizes anticipated data needs for the Methylene Bis(Thiocyanate) Case in 

this document (Final Work Plan), Product Chemistry, Environmental Fate, and Ecological 

Effects Scoping Document in Support of Registration Review of Methylene bis(thiocyanate), and

Methylene Bis Thiocyanate (MBT): Human Health Risk Assessment Scoping Document in 

Support of Registration Review.

Guideline 

Number Anticipated Data Requirement Test Material 

Estimated 

Timeframe 

(Measured 

in months 

from DCI 

Receipt) 

875.1700 Product use information (handler) TGAI 12 

875.2700 Product use information (postapplication) TGAI 12 

875.2800 Description of human activity TGAI 12 

875.1200 Dermal indoor exposure TGAI 24 

875.1400 Inhalation indoor exposure TGAI 24 

875.1600 Application exposure data reporting and calculations TGAI 24 

875.2900 Data reporting and calculations TGAI 24 

875.2500 Inhalation Exposure TGAI 24 

875.2300 Indoor Surface Residue Dissipation3 TGAI 24 

835.2240 Photodegradation in water (at pH 5) TGAI 12 

835.1240 Adsorption/Desorption Study TGAI 12 

835.4300 Aerobic Aquatic Metabolism Study TGAI 12 

835.4400 Anaerobic Aquatic Metabolism Study TGAI 12 

850.6800 Modified activated sludge, respiration inhibition test 4 TGAI 12 

 

3

 The anticipated DCI will provide that a protocol must be submitted for review and approval by the Agency prior to 

initiating this study. 

4

The results of the Activated Sludge Respiration Inhibition Test (ASRI) that is expected to be required would 

determine which of these three biodegradation tests would be anticipated to be required. If the ASRI test EC50 is 

less than or equal to 20 mg/L, then either the Biodegradation in Activated Sludge Study or Simulation Test – 

Aerobic Sewage Treatment: A. Activated Sludge Units or the Porous Pot Test would be anticipated to be required. 

If the ASRI test EC50 is greater than 20 mg/L, then the applicant would choose to conduct either: (i) Ready 

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

Activated Sludge Units or the Porous Pot Test. If the antimicrobial passes the ready biodegradability study, then no 

further testing would be expected to be required. If, however, the antimicrobial fails the ready biodegradability 
Docket Number: EPA-HQ-OPP-2011-0613 

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835.3110 Ready Biodegradability4 TGAI 12 

835.3220 Porous Pot Test4 TGAI 12 

835.3240 

Simulation Test – Aerobic Sewage Treatment: A. Activated 

Sludge Units4 TGAI 12 

835.3280 

Simulation Tests to Assess the Biodegradability of 

Chemicals Discharged to Wastewater4 TGAI 12 

850.1400 Fish early-life stage toxicity test (freshwater) TGAI 12 

850.4400 Aquatic plant toxicology test using Lemna spp., Tier I TGAI 12 

850.5400 Algal Toxicity Tier I and Tier II TGAI 12 

850.3020 Honey bee acute contact toxicity TGAI 12 

850.3030 Honey bee toxicity of residues on foliage TGAI 12 

850.1735 Whole sediment acute toxicity invertebrates (freshwater)5 TGAI 12 

850.1740 Whole sediment acute toxicity invertebrates (marine)5 TGAI 12 

Special Study Chronic sediment toxicity test (freshwater invertebrate) 5 TGAI 12 

 study, then the Biodegradation in Activated Sludge or Simulation Test – Aerobic Sewage Treatment: A. Activated 

Sludge Units, or the Porous Pot study would be expected to be required. 

5

 If the environmental fate data anticipated as being required for this registration review demonstrate that the halflife of the MBT in the sediment is greater than 10 days and if any one of the following conditions are met (1) Kd 

<50, (2) Koc <1000, or (3) Kow <3, then the registrant may request that the Agency waive the sediment studies.