1 **Section 18 Emergency Exemption Application TYPE OF EXEMPTION BEING REQUESTED** 

 SPECI FIC  **QUARANTINE**  PUBLIC HEALTH **CONTACT PERSON(S) AND QUALIFIED EXPERT(S) (166.20(a)(1)) CONTACT PERSON:**  **Name:** David Hickens **Title:** Chief, NASA JSC Environmental Office **Organization:** NASA JSC **Address: Phone**  **:** 281
- 483
- 3120 **QUALIFIED EXPERT: Name:**  Mark E. Wilson **Title:** Boeing Associate Technical Fellow **Organization:** Boeing **Address :**  3100 space Center Blvd., M C HB3
- 20, Houston TX 77059
- 3556 **Phone :**  281
- 226
- 6966

**DESCRIPTION OF PESTICIDE S**  **REQUESTED (166.2O(a)(2)) Common Chemical**  **Name s**  **(Active Ingredient s**  **):** o - phthalaldeh yde (OPA) CAS Number 643
- 79
- 8 **Trade Names and EPA Reg. Nos .:**  **Formulation s**  **:** Immobilization of OPA on a Porous Resin (P/N SV1012327
- 2) **% Active Ingredient**  **:** 0.25 g OPA/cm 3 of resin ; Resin L oading factor based on 84% elution efficiency = 210 mg OPA/cm 3 resin **Manufacturers :**  o - phthalaldehy de

– Sigma Aldrich; OPA Resin (P/N SV1012327
- 2)

– Hamilton Sundstrand

DESCRI PTION OF PROPOSED USE (166.20(a)(3)) **Sites to be Treated:** International Space Station Internal Active Thermal Control Sy stem (IATCS) coolant including the US Laboratory including Node 1 and Airlock (249 liters),2

Japanese Experiment Modu le (213 liters), Columbus (160 liters), and Node 3 (194 liters). **Method of Application :**  Elution of OPA from the OPA Resin (P/N SV1012327
- 2) into the IA TCS coolant volume through the use of an antimicrobial applicator canister ( P/N 683
- 63436) placed in a b y - 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 OPA added to each loop approximately

1/y ear. **Maximum Number of Applications:** Approximately 1 application/y ear for each loop, determined by

measuring OPA concentration every 90 day s and util ization of the quantity of OPA R esin 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 L aboratory
- 2 72 liters, Japanese Experiment Module

– 213 liters, Columbus

– 1 5 0 liters, and Node 3

– 194 liters for a total volume of 8 29 liters. **Total Amount of Pesticide to be Used (in terms of a.i. and product):** V R = Volume Resin Required ; V L = Volume of IATCS (L); [OPA] = Desired OPA Concentration (mg/L); F OPA = OPA Resin L oading factor = 210 mg OPA/cm 3

- Resin; Therefore V R = (V L * [OPA])/ F OPA ; V R = ( 8 29 L * 250 mg/L)/210 mg OPA/cm 3 = 987 cm 3 OPA Resin/y ear . **Use Season (period of time for w hich 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)” Revi sion 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 phy sicall y constrained in a porous methacrylate resin material. Once the resin material was exposed to the coolant fluid, the OPA effectivel y eluted from the resin material into the aqueous phase. This implementation was selected due to sy stem requirements and the use of pre - existing flight hardware. Sy stem requirements included limits on the initial and final OPA concentration observed eluting from the canister (reactor) and compatibility w ith the coolant loop chemistry (i.e. no leachate, particles, adverse effects to chemistry /sy stem materials). The flight hardware used for the OPA delivery

w as a stainless steel canister with an approximate volume of 2.0 L with flex hoses and quick disconnects to connect the canister to a payload rack location.3

**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 sy stem; the ability

to control existing planktonic and biofilm residing micro
- organisms; a negligible impact on s ys tem 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; Chem ical Compatibility 3x; Safety

/Toxicity 3x; Disinfection Effectiveness 2x; Stability 2x; By product Acceptability

2x; On
- orbit Implementation 1x; Cost 1x; In - Flight Monitoring 1x; and Technology Readiness 1x. 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
. T rade studies and rapid screening assay s were used to develop a prioritized list of acceptable antimicrobial agents including glutaraldehyde, ortho
- phthalaldehy de (OPA), and methyl isothiazolone
. Glutaraldeh yde at greater than 25 ppm was eliminated due to NASA concerns with safet y and toxicity and meth yl isothiazolone was eliminated from further consideration due to its ineffectiveness against biofilms and toxicity at higher concentrations. Therefore, OPA, an aromatic dialdeh yde compound with the formul a C 6 H 4 (CHO) 2 was selected for qualification testing for use as a biocide in the IATCS. **Alternative Control Practices:** Lowering the water activit y of the coolant by increasing salt concentration was ruled out due to requirements for surface tension specif ied 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 dy nes/cm at 20  C. **EFFICACY OF USE PROPOSED UNDER SECTION 18 (166.20(a)(5)) (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 (P/N SV1012327
- 2) into the IATCS coolant volume through the use of an antimicrobial applicator canister (P/N 683
- 63436) placed in a by
- pass line at a p ayload rack location in the U.S. L aboratory

Module, Columbus Module, Japanese Experiment Module, and/or Node 3 and initiating flow at 400 lb/hr for 16 hours.4

**Possible risks posed by use:** Evaluations of the toxicity of OPA 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 therap y for all toxicology parameters. Initial effluent concentrations of OPA greater than 1000 ppm introduced into a pay load b y pass 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 therap y due to irritation of soft tissues s uch as the ey e . If coolant containing OPA leaks and the water evaporated until OPA became saturated, the resulting concentrate would be a severe ey e irritant classified as a Toxicity Hazard Level 2 defined as moderate to severe irritation that has the potential for long
- ter m performance decrement and will require therap y. Solid OPA was determined to be a Toxicity Hazard Level 2 (Catastrophic) for ey e and skin irritancy and a Toxicity Hazard Level 1 (Critical) for inhalational and sy stemic toxicity . OPA in rare instances ha s caused allergic reactions from repeated skin contact with residual liquids or solids. OPA loaded resin beads containing 0.25 g/cm 2 OPA in the antimicrobial applicator was assessed as a Toxicity Hazard Level 0 (Nonhazard). JSC Toxicology

provided additi onal assessment of the risk of solid OPA from IATCS fluid in Memo Tox - HG
- 2009
- 09 dated April 30, 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 ey e, consideration of the behavior of liquids under the specific spaceflight conditions expected on ISS led to the conclusion that contact with the ey es 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 ey e hazards. JSC Toxicology recommended that leaks from the antimicrobial applicator and the IA TCS should be qui ckly

r emoved before evaporation occurs. Leakage detection on - orbit is primarily based on thermal control sy stem 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 sy stem effects were detected from OPA utilization. Ambersorb 572 ® was chosen as the flight candidate since it had approximately twic e 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 affinit y for free OPA. 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)(8))**  Not Applicable5 **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)(11)) (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 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 Sy stem. Also, the equipment was chemically cleaned with isopropanol, rins ed 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 p arts 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 (m l ) to greater than 1
. 0 E+0 6 CFU/100 m l
.6

**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 sy stem and pote ntiall y i mpact human health if opportunistic pathogens become established in the sy stem. Microorganisms are capable of degrading the coolant chemistry , attaching to surfaces and forming biofilm, subsequent biofouling of filters, tubing, and pumps, decreas ing 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 t o maintain tolerable risk levels for the ISS IATCS due to the required operational life of the ISS IATCS for over 15 y ears without the ability to periodicall y flush and replace coolant, sterilize the sy stem, and/or replace s ys tem 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 unit s 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 (MI C) 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 ML C 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 an y unexpected adverse effects which resulted from use of the pesticide under the exemption; (4) The results of an y monitoring required and/or carried out under the exemption; (5) A discussion of an y enforcement actions taken in connection with the exemption; (6) Method(s) of disposition of a food or animal feed , if required to be destroy ed under an exemption; and (7) An y other information requested b y the Administrator , such as the t ype of PPE worn by applicators
.