National Aeronautics and 

Space Administration 

Lyndon B. Johnson Space Center 

2101 NASA Parkway 

Houston, Texas 77058-3696 

Reply to Attn. of:: JE-15 -0 59 

Ms. Deborah Rate, PhD 

U.S. EPA, Office of Pesticide Programs Division 

RIMUERB/Emergency Response Team 7 505P 

One Potomac Yards -7th Floor 

2777 S. Crystal Drive 

Arlington, VA 22202 

NOV 2 5 2015 

RE: Request for FIFRA Emergency Exemption Certification Renewal for ISS 

Dear Ms. Rate: 

Please find attached for your review and consideration NASA's request for recertification of 

our specific emergency exemption application, for use of Ortho-phthalaldehyde (OPA) on 

board NASA's International Space Station (ISS) in the Internal Active Thermal Control 

System (IA TCS) coolant. 

The ISS Program has been extended to FY 2020, and NASA seeks approval of this request 

for recertification of our application for use of OPA on board the ISS. A preliminary 

determination was made by the EPA that this use pattern is eligible for the re-certification 

program as prescribed under 40 CFR 166.20(b)(5). NASA HQ has been in negotiation with 

the EPA HQ Office of Pesticide Programs discussing registration issues pertaining to use of 

OPA on-board the ISS. The prior approved exemption is attached. 

For this re-certification request, we rely upon all previously submitted information, attached, 

and have provided a current interim report, in satisfaction of 40 CFR 166.20(a)(1) thru 

(a)(lO) and paragraphs (b)(l) through (b)(4), and we meet all of the conditions specified at 40 

CFR 166.20(b)(5)(i) through (iv) and additionally certify that (v)(A) through (E) are true. 

Should you have questions regarding our request, please contact me at (281) 483-3120. 

Thank you in advance for you assistance and cooperation in this matter. 

!... 

ckens, C ief I 

JSC Environmen al Office 

Enclosures 
Enclosure 1 
Section 18 Emergency Exemption Application 

TYPE OF EXEMPTION BEING REQUESTED 

0 SPECIFIC 

D QUARANTINE 

D PUBLIC HEALTH 

CONTACT PERSON(S) AND QUALIFIED EXPERT(S) (166.20(a)(l)) 

CONTACT PERSON: QUALIFIED EXPERT: 

Name: David Hickens Name: Mark E. Wilson 

Title: Chief2 NASA JSC Environmental Title: Boeing Associate Technical Fellow 

Office 

Organization: Boeing 

Organization: NASA JSC 

Address: 499 Boeing Blvd., MC JN-08, 

Address: Huntsville, AL 35824 

Phone: 256-77 4-8909 

Phone: 281-483-3120 

DESCRIPTION OF PESTICIDES REQUESTED (166.20(a)(2)) 

Common Chemical Names 

(Active Ingredients): o-phthalaldehyde (OPA) CAS Number 643-79-8 

Trade Names and EPA Reg. Nos.: 

Formulations: Immobilization of OPA on a Porous Resin (PIN SV1012327-2) % Active 

Ingredient: 0.25 g OP A/cm3 of resin; Resin Loading factor based on 84% elution efficiency = 

210 mg OPA/cm3 resin 

Manufacturers: o-phthalaldehyde- Sigma Aldrich; OPA Resin (PIN SV1012327-2)-

Hamilton Sundstrand 

DESCRIPTION OF PROPOSED USE (166.20(a)(3)) 

Sites to be Treated: International Space Station Internal Active Thermal Control System 

(IA TCS) coolant including the US Laboratory including Node 1 and Airlock (249 liters), 

1 
Japanese Experiment Module (213 liters), Columbus (150 liters), and Node 3 (194liters). 

Method of Application: Elution of OPA from the OPA Resin (PIN SV1012327-2) into the 

IATCS coolant volume through the use of an antimicrobial applicator canister (PIN 683-

63436) placed in a by-pass line at a payload rack location and initiating flow at 400 lb/hr for 

16 hours. 

Rate of Application (in terms of a.i. and product): Approximately 250 mg/L OP A added to 

each loop approximately 1/year. 

Maximum Number of Applications: Approximately 1 application/year for each loop, 

determined by measuring OPA concentration every 180 days and utilization of the quantity of 

OPA Resin necessary to increase the as circulated in flight hardware OPA concentration to 

300 ppm based on degradation of OPA to 50- 100 ppm. 

Total Acreage (or other units) to be Treated: US Laboratory- 272 liters, Japanese 

Experiment Module- 213 liters, Columbus- 150 liters, and Node 3- 194liters for a total 

volume of 829 liters. 

Total Amount of Pesticide to be Used (in terms of a.i. and product): VR =Volume Resin 

Required; VL =Volume of IATCS (L); [OPA] =Desired OPA Concentration (mg/L); FoPA = 

OPA Resin Loading factor= 210 mg OPA/cm3-Resin; Therefore VR = (VL * [OPA])/ FoPA; 

VR = (829 L * 250 mg/L)/210 mg OPA/cm3 = 987 cm3 OPA Resin/year. 

Use Season (period of time for which use of chemical is requested): As required through 

the life of the International Space Station to maintain the OPA concentration as circulated in 

flight hardware between 25 - 500 ppm OPA as specified in Table 4.1-2.8 "Heat transport fluid 

(IATC)" Revision E of SSP-30573 "Space Station Program Fluid Procurement and Use 

Control Specification". 

Additional Restrictions, User Precautions and Requirements, Qualifications of 

Applicators, etc.: The method to deliver OPA to the IA TCS coolant was an immobilization 

of the active biocide to a solid substrate. The immobilization process involved a solvent 

evaporation technique that allowed the OPA to be physically constrained in a porous 

methacrylate resin material. Once the resin material was exposed to the coolant fluid, the OPA 

effectively eluted from the resin material into the aqueous phase. This implementation was 

selected due to system requirements and the use of pre-existing flight hardware. System 

requirements included limits on the initial and final OPA concentration observed eluting from 

the canister (reactor) and compatibility with the coolant loop chemistry (i.e. no leachate, 

particles, adverse effects to chemistry/system materials). The flight hardware used for the 

OPA delivery was a stainless steel canister with an approximate volume of 1.0 L with flex 

hoses and quick disconnects to connect the canister to a payload rack location. 

2 
ALTERNATIVE METHODS OF CONTROL (166.20(a)(4)) (Efficacy data and/or other 

information included as a separate attachment) 

Registered Alternative Pesticides: An extensive evaluation of biocides was conducted to 

down-select to several candidates for test trials (see Appendix A). Criteria for that down-select 

included: the need for safe, non-intrusive implementation and operation in a functioning 

system; the ability to control existing planktonic and biofilm residing micro-organisms; a 

negligible impact on system wetted materials of construction; and a negligible reactivity with 

existing coolant additives. A five-point ordinal rating scale from 5 (excellent) to 1 

(unacceptable) was used to score each biocide against 10 weighted assessment criteria: 

Material Compatibility 4x; Chemical Compatibility 3x; Safety/Toxicity 3x; Disinfection 

Effectiveness 2x; Stability 2x; Byproduct Acceptability 2x; On-orbit Implementation lx; Cost 

lx; In-Flight Monitoring lx; and Technology Readiness lx. All oxidizing biocides and 

halogens were eliminated due to increased corrosion of nickel brazes on cold plates and heat 

exchangers. Phenols were eliminated due to instability in the coolant. Quaternary 

ammoniums were eliminated due to their reduction of surface tension which increases gas trap 

leakage. Trade studies and rapid screening assays were used to develop a prioritized list of 

acceptable antimicrobial agents including glutaraldehyde, ortho-phthalaldehyde (OP A), and 

methyl isothiazolone. Glutaraldehyde at greater than 25 ppm was eliminated due to NASA 

concerns with safety and toxicity and methyl isothiazolone was eliminated from further 

consideration due to its ineffectiveness against biofilms and toxicity at higher concentrations. 

Therefore, OPA, an aromatic dialdehyde compound with the formula C6H4(CH0)2 was 

selected for qualification testing for use as a biocide in the IATCS. 

Alternative Control Practices: Lowering the water activity of the coolant by increasing salt 

concentration was ruled out due to requirements for surface tension specified in SSP-30573 

Revision B, Space Station Program Fluid Procurement and Use Control Specification. 

Requirement specifications included chlorides less than 1.0 ppm and a surface tension of 72-

77 dynes/em at 20°C. 

EFFICACY OF USE PROPOSED UNDER SECTION 18 (166.20(a)(S)) (Efficacy data 

and/or other information included as a separate attachment) 

EXPECTED RESIDUE LEVELS IN FOOD (166.20(a)(6)) (Residue data included as 

separate attachment) Not Applicable Due to Removal by ISS ECLSS 

DISCUSSION OF RISK INFORMATION (166.20(1)(7)) 

(Potential risks to human health, endangered or threatened species, beneficial organisms, 

and the environment) 

Description of application sites, including proximity to residential areas, aquatic systems, 

endangered or threatened habitats, soil types, etc.: Elution of OPA from the OPA Resin 

(PIN SV1012327-2) into the IATCS coolant volume through the use of an antimicrobial 

applicator canister (PIN 683-63436) placed in a by-pass line at a payload rack location in the 

U.S. Laboratory Module, Columbus Module, Japanese Experiment Module, and/or Node 3 

and initiating flow at 400 lb/hr for 8 hours. 

3 
Possible risks posed by use: Evaluations of the toxicity of OP A were conducted by Martin 

E. Coleman, Ph.D., Wyle Toxicology Consultant, and the results were reported in Memo 632 

dated March 4, 2005, Memorandum TOX-MC-2007-Draft dated August 27, 2007 and 

Memorandum TOX-MC-2008-Draft dated March 24,2008. Circulated concentrations of OPA 

up to 500 ppm were determined to be Toxicity Hazard Level 0 (Nonhazard) defined as slight 

irritation that lasts <30 minutes and will not require therapy for all toxicology parameters. 

Initial effluent concentrations of OP A greater than 1000 ppm introduced into a payload bypass stream from the antimicrobial applicator were determined to be a Toxicity Hazard Level 

1 (Critical) defined as slight to moderate irritation that lasts >30 minutes and will require 

therapy due to irritation of soft tissues such as the eye. If coolant containing OPA leaks and 

the water evaporated until OPA became saturated, the resulting concentrate would be a severe 

eye irritant classified as a Toxicity Hazard Level 2 defined as moderate to severe irritation that 

has the potential for long-term performance decrement and will require therapy. Solid OPA 

was determined to be a Toxicity Hazard Level 2 (Catastrophic) for eye and skin irritancy and a 

Toxicity Hazard Level 1 (Critical) for inhalational and systemic toxicity. OPA in rare 

instances has caused allergic reactions from repeated skin contact with residual liquids or 

solids. OPA loaded resin beads containing 0.25 g/cm2 OPA in the antimicrobial applicator 

was assessed as a Toxicity Hazard Level 0 (Nonhazard). 

JSC Toxicology provided additional assessment of the risk of solid OP A from IA TCS fluid in 

Memo Tox-HG-2009-09 dated April30, 2009. This memo documents the JSC Toxicology 

Group's assessment of dry OPA from evaporated ITCS fluid as a Toxicity Hazard Level 0, 

rather than a Toxicity Hazard Level 2. Although solid OPA could cause catastrophic eye 

damage if it were to contact the eye, consideration of the behavior of liquids under the specific 

spaceflight conditions expected on ISS led to the conclusion that contact with the eyes of dry 

OPA from evaporated ITCS fluid is not credible. Thus, dried OPA films from evaporated 

ITCS fluid should not be considered Toxicity Hazard Level 2 eye hazards. 

JSC Toxicology recommended that leaks from the antimicrobial applicator and the IA TCS 

should be quickly removed before evaporation occurs. Leakage detection on-orbit is primarily 

based on thermal control system accumulator quantities. 

Proposals to mitigate risks: A removal resin was developed to be able to remove OPA from 

the IATCS in the event of a sustained leak to preserve crew health and safety or if adverse 

system effects were detected from OPA utilization. Ambersorb 572® was chosen as the flight 

candidate since it had approximately twice the capacity for OPA than the activated carbon. 

The resin material has a much more porous structure, resulting in higher surface area to 

facilitate organic adsorption. The resin was also shown to remove greater than 95% of OPA 

degradation products from IA TCS coolant but it has a higher affinity for free OP A. The 

removal resin canister may be attached at a payload rack location similar to antimicrobial 

applicator. 

COORDINATION WITH OTHER AFFECTED FEDERAL, STATE, AND LOCAL 

AGENCIES (166.20( a)(S)) 

Not Applicable 

4 
NOTIFICATION OF REGISTRANT (166.20(a)(9)) 

ENFORCEMENT PROGRAM (166.20(a)(10)) (Explanation of legal authority and 

program resources for enforcement) 

REPEAT USES (166.20(a)(ll)) (If use being requested is a repeat use, and final report 

has not been filed, interim final report included as a separate attachment) 

PROGRESS TOWARD REGISTRATION (166.25(b)(2)(ii) (Information from registrant 

concerning the current status ) (Not Required for Request for a Quarantine Exemption) 

NASA has developed a draft application package and is beginning the registration process. 

NAME OF PEST (166.20(c)(I)) 

Scientific Name: Cupriavidus metallidurans, Variovorax paradoxus, Acidovorax sp., 

Sphingomonas parapaucimobilis, Stenotrophomonas maltophilia, Methylobacterium 

extorquens, and Unidentified Gram Negative Rods 

Common Name: Aerobic/Microaerophilic Water Bacteria 

ORIGIN OF INTRODUCED PEST (166.20(c)(2)) 

Origin of pest, means of its introduction, and spread into the area (if known): 

The primary source of bacteria was from the deionized water used to make the coolant for the 

Internal Active Thermal Control System. Also, the equipment was chemically cleaned with 

isopropanol, rinsed with deionized water and dried prior to assembly. The bacteria may also 

have been introduced during handling and assembly. A silver salt biocide, silver sulfate, 

initially used as an additive in the coolant formulation at a concentration of 0.1 - 3 parts per 

million (ppm) to control growth and proliferation of microorganisms rapidly decreased below 

detection limits within a few hours. Silver ions rapidly underwent an oxidation reduction 

reaction with nickel. The rapid reduction of silver ions in the coolant created a favorable 

environment for the growth and proliferation of microorganisms. Counts of heterotrophic 

bacteria increased from <10 colony forming units (CFU)/100 milliliters (ml) to greater than 

l.OE+06 CFU/100 ml. 

5 
IMPACT OF THE PEST (166.20(C)(3)) 

Anticipated impact of not controlling the pest, and other information pertinent to 

economic importance of this pest: 

Uncontrolled microbiological growth in the IATCS can deteriorate the performance of the 

system and potentially impact human health if opportunistic pathogens become established in 

the system. Microorganisms are capable of degrading the coolant chemistry, attaching to 

surfaces and forming biofilm, subsequent biofouling of filters, tubing, and pumps, decreasing 

flow rates, reducing heat transfer, initiation and acceleration of corrosion, and enhanced 

mineral scale formation. Disinfection to control microbiological growth and biofilm 

formation is necessary to maintain tolerable risk levels for the ISS IA TCS due to the required 

operational life of the ISS IA TCS for over 15 years without the ability to periodically flush 

and replace coolant, sterilize the system, and/or replace system equipment. 

Information Required for a Final Report 

SAMPLE SECTION 18 EMERGENCY EXEMPTION FINAL REPORT FORMAT (40 CFR 

166.32) 

(1) Total acreage, number of structures or other units treated, and the total quantity of the 

pesticide used (either actual or estimated); 

(2) A discussion of the effectiveness of the pesticide in dealing with the emergency condition; 

the minimum inhibitory concentration (MIC) for OPA against the bacteria in the IATCS is 10 

- 20 ppm. The minimum lethal concentration (MLC) for OPA against most of the identified 

bacteria in the IATCS is 30- 50 ppm. However, the MLC of OPA against Methylobacterium 

extorquens was determined to be 150-200 ppm. Expected use concentration of 300 ppm 

OPA is more than ten times higher than the MIC. And provides effective disinfection and 

microbiological growth control. 

(3) A description of any unexpected adverse effects which resulted from use of the pesticide 

under the exemption; 

(4) The results of any monitoring required and/or carried out under the exemption; 

(5) A discussion of any enforcement actions taken in connection with the exemption; 

(6) Method(s) of disposition of a food or animal feed, if required to be destroyed under an 

exemption; and 

(7) Any other information requested by the Administrator, such as the type of PPE worn by 

applicators. 

6 
Enclosure 2 
FIFRA SPECIFIC USE EXEMPTION - INTERIM REPORT 

(1) Total acreage, number of structures or other units treated, and the total quantity of the pesticide 

used (either actual or estimated) - Samples of Internal Active Thermal Control System (IATCS) 

coolant were collected from treated units on the International Space Station (ISS) during December 

2014. The IATCS samples were returned to ground on Space X in February 2015 for analyses including 

OPA concentration and heterotrophic bacteria enumeration. The concentrations of o-phthalaldehyde 

(OPA) in the Japanese Experiment Module= 295 ppm, Columbus= 83.9 ppm, Node 3 = 164 ppm, and 

US Laboratory = 296 ppm. A canister containing 235 cm3 OPA resin was applied to the Columbus 

Module on 1/30/2015 to provide approximately 300 ppm OPA in the coolant. The actual measured 

concentration in the Columbus Module after OP A application on 1130/2015 was 171 ppm. Complete 

dissolution and elution of the OPA in the canister did not occur possibly due to clumping of the OPA or 

partial blockage of a flow tube in the canister. Currently no re-additions of OPA are planned in 2016. 

This treatment plan is in compliance with the EPA exemption 11D001 which limits OPA in each treated 

unit to 50 - 500 ppm, limits application of OPA to each loop to once per year, and limits the volume of 

OPA resin/year to 1974 cm3

. 

(2) A discussion of the effectiveness of the pesticide in dealing with the emergency condition - The 

minimum inhibitory concentration (MIC) for OP A against the bacteria in the IA TCS is 10 - 20 ppm. 

The minimum lethal concentration (MLC) for OP A against most of the identified bacteria in the IA TCS 

is 30-50 ppm. However, the MLC of OPA against Methylobacterium extorquens was determined to be 

150 - 200 ppm. The use concentration of 300 - 400 ppm OP A is more than ten times higher than the 

MIC and provided effective disinfection and microbiological growth control which has consistently been 

verified in return to ground samples with 7 day counts for heterotrophic bacteria on R2A agar at 28°C. 

Heterotrophic bacteria counts in all of the treated IATCS coolant samples collected in December 2014 

and returned on Space X in February 2015 were <10 colony forming units (CFU)/100 mL. This 

indicates that OP A has provided the proper level of disinfection and is effective at controlling 

microbiological growth. 

(3) A description of any unexpected adverse effects which resulted from use of the pesticide under the 

exemption -There have been no unexpected adverse effects resulting from the use of OPA in the ISS 

IA TCS coolant. 

(4) The results of any monitoring required and/or carried out under the exemption- As discussed 

above in response to reporting the total quantity of OPA used during the year, return to ground samples 

are collected and returned to ground once per year and OPA concentrations in each loop are determined 

every 180 days on-orbit using a rapid colorimetric test strip. During the period from 04/15/2014 to 

01130/2015, OPA concentrations in all treated units have remained from 50-500 ppm. The graph 

below documents the historical on-orbit OPA concentrations for all of the treated loops. 
c 

~ 

On-Orbit OPA Concentrations 

60 0 ,--~ fRRtei et:riire"8tmmeffinttio5Datete.sS:: --~ Retreatment Dates: US Lall -615108 (target300ppm) JEiol -10/6109(target · 280 ppm) 

Columllus _ 1116108 (target 250 ppm) Columbus - 1112110 (target ·300 ppm) 

JEI.l _ 11123108 (target200 ppm) US Lab -1125/10 (target v300 ppm) '------- ----' Node 3-4121/11 (target-300 ppm) 

Retreatment Dales: 

JEM -6122/12 (target ·250 ppm) 

US Lab - 1/8113 (target -400 ppm) 

SOOTI=========~~~=,----------------------------~~-----1 Las! sample readings before launch: 

Node 2 LTL (Feb. 2007)- 76.3 ppm 

Node 21.1TL (Feb. 2007)-n.3 ppm 

Columbus (Sept. 2007) - 87 ppm 

JEI.I (Aug. 2007) - 87 ppm 

Node 3 LTL (June 2009) - 291 ppm 

Node 3 MTL (June 2009) - 302 ppm 

~ 300 +------------~c-----------------------~r-----~ c 

G) 

u 

c 

0 

(J 

200 +---------~---~~---~~------~~-------------------4 0 

• 

0 +----...;111 ... -e-~ l--.---~ ' ' ' ' ' 1 I 

3128107 3127108 3127109 3/27/10 3/28/ 11 3/27112 3/27113 3/28/14 3/28/15 3/27/16 

Sample Date 

--usLab --Node2LTL Node 2 t.ITL -columbus ---+--- Te.st Bed 

---Action Limit(High) ---Action Limit(Low) ~JEI.I --Nod e3LT L Node 31.1Tl 

(5) A discussion of any enforcement actions taken in connection with the exemption - No enforcement 

action was required during the 4115/2014 to 11/1112015 exemption period other than compliance with 

the guidelines identified in Exemption 11D001. The use of OPA resin was limited to operations per 

SSP 30573 "Space Station Program Fluid Procurement and Use Control Specification", limitation of 

crew exposure through the use of personal protective equipment including protective eyewear and 

chemical resistant gloves, clean-up of leaks or spills, periodic OPA concentration measurement, and 

historical documentation. 

(6) Method(s) of disposition of a food or animal feed, if required to be destroyed under an exemption 

- None/Not applicable. 

(7) Any other information requested by the Administrator, such as the type of PPE worn by 

applicators- All applicable directions, restrictions, precautions and MSDS instructions were 

adhered to and followed to ensure crew safety. Crew wear chemical resistant gloves, safety glasses, 

and use splash shields to protect eyes and skin from contact with OPA during loop applications. OPA is 

eluted from the resin by placement in an unoccupied by-pass line in a payload rack and initiating flow. 

Eluted concentrations of OPA <1000 ppm are quickly diluted in minutes to 50-500 ppm OPA through 

mixing during circulation. 
Enclosure 3 
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

National Aeronautics and Space Administration 

JSC Environmental Office 

21 0 I NASA Parkway 

Houston, TX 77058 

Date Issued: November 26, 2014 

Expiration Date: November 26, 2015 

Report Due: May 26, 2016 

File Symbol: 140001 

Attn: David Hickens I Thomas M. Hayes, III 

OFFICE OF CHEMICALSAFETY 

AND POLLUTION PREVENTION 

The Environmental Protection Agency hereby issues a specific exemption under the provisions 

of section 18 of the Federal Insecticide, Fungicide, and Rodenticide Act, as amended, to the 

National Aeronautics and Space Administration (NASA) for use of ortho-phthalaldehyde 

immobilized to a porous resin to treat the International Space Station (ISS) internal active 

thermal control system (lA TCS) coolant including the United States (US) Laboratory, the 

Japanese Experiment Module, the Columbus, and Node 3 to control aerobic/microaerophilic 

water bacteria such as Cupriavidus metallidurans, Variovorax paradoxus, Acidovorax sp., 

Sphingomonas parapaucimobilis, Stenotrophomonas mallophilia, Methylobacterium 

extorquens, and unidentified gram negative rods. This specific exemption is subject conditions 

set forth in your request, dated August 8, 2014, as well as the following: 

1) NASA is responsible for ensuring that all provisions of this specific exemption are met. 

NASA is also responsible for providing information in accordance with 40 Code of Federal 

Regulations (CFR) §166.32(b). Accordingly, a report summarizing the results of this 

program must be submitted to EPA Headquarters within 6 months following the expiration 

of this exemption, or prior to requesting another specific exemption for this use. In 

accordance with 40 CFR § 166.32 (a), this office shall also be immediately informed of any 

adverse effects resulting from the use of this pesticide in connection with this exemption. 

Any future correspondence regarding this exemption should refer to file symbol: 14D001. 

2) The unregistered active ingredient, ortho-phthalaldehyde (OPA; CAS# 643-79-8), 

immobilized in a porous resin (OPA resin) obtained from Hamilton Sundstrand, may be 

used. All applicable directions, restrictions, precautions and instructions from the Material 

Safety Data Sheet (MSDS) must be adhered to. 
Page 2 of2 

3) OP A may be applied to the ISS lA TCS loops such that each volume concentration is in the 

range of of 50-500 ppm. The treated volume, including the US Laboratory (272 L), 

Japanese Experiment Module (213 L), Columbus (150 L), and Node 3 (194 L) will total 

829 L ( l ,974 cm3 OPA resin/year). A maximum of 1 application per loop may be made. 

4) Use of the OPA resin, pursuant to this exemption shall be limited to operations conducted 

by NASA as per SSP-30573 "Space Station Program Fluid Procurement and Use Control 

Specification.'' The OPA will elute from the resin when the resin is exposed to the IATCS 

coolant volume through the use of an antimicrobial applicator canister placed in an 

unoccupied by-pass line and initiating flow. 

5) NASA is responsible for ensuring that the application process is carried out safely and that 

the potential risk to crew members from exposure is minimized by requiring use of 

personal protective equipment (PPE) during applications, including protective eyewear and 

chemical resistant gloves. This PPE will also be used in the event of clean-up of any spills 

and leaks, in accordance with contingency plans in place. 

6) This is the fourth year that this use has been requested under Section 18 of FIFRA by 

NASA. NASA is actively pursuing a registration for this use. 

If you or your staff have any questions regarding this authorization. please contact Emergency 

Response Team member, Andr~a Conrath (703.308.9356; conrath.andrea"i(epa.go\ ) or the 

Emergency Response Team Leader, Tawanda Maignan (703.308.8050; 

maignan \~anda:lvcpa .gO\ ). 

Susan 

Q~Wl Lewis, Director cf~ Registration Division 

Date: 11/;. tP /;y