Revision Date: October 15, 2006 American Biological Safety Association 49th Annual Biological Safety Conference Effects of Relative Humidity, Concentration, and Exposure Time on the Efficacy of Chlorine Dioxide Gas Decontamination Mark A. Czarneski Director of Technology 1
Overview 1. Define Experiment and Chlorine Dioxide gas 2. Define Chlorine Dioxide Decontamination Parameters 3. Results 4. Other Recent Data 5. Conclusions 2
Experiment Questions Does RH affect spore log reductions with CD Gas?? Does CD Gas concentration / time affect spore log reductions?? How to Do Expose 6-log biological indicators (BI s) at various RH (45%, 55% & 65%) for different exposure times Minimum of 3 BI s per run Some runs had BI s placed in BI Challenge Fixture to simulate small gaps (0.185 [4.7mm]) All BI s stored at 45% RH prior to decontamination cycle 3
Chlorine Dioxide Fumigation True Gas (boiling point 11 o C) Short Contact times (0.5-2 hours) Fast overall cycle times (fast aeration) Non - carcinogenic Water Soluble Non - Flammable No post exposure cleanup required Direct vented or scrubbed at end of exposure Low concentrations (360-1800 ppm) Scaleable by adding a generator for every 30,000 cubic feet (70,000 cu-ft can be done with a 6.6-hour exposure) EPA Registered as a Sterilant NSF approved for BSC Decontamination 4
Chlorine Dioxide Generation Technology Cl 2(g) + 2NaClO 2(s) 2ClO 2(g) + 2NaCl (s) Performed in solid phase Gas generated on demand Self-Contained reagents Simple to replace consumables Only pure gas is delivered to the chamber, the salt solid remains in the CD Cartridge 5
The Chlorine Dioxide Decontamination Process Pre-Conditioning Raise RH 45%, 55% or 65% Conditioning Dwell time at RH SP (5 min) Charge Raise CD Concentration 1 mg/l Exposure Dwell time at CD SP (to achieve x ppm-hrs) Aeration Remove CD Gas 12-15 air exchanges 6
8:43:29 8:48:29 8:53:30 8:58:29 9:03:30 9:08:29 9:13:29 9:18:28 9:23:28 9:28:28 9:33:28 9:38:28 9:43:28 9:48:29 9:53:28 9:58:28 10:03:29 10:08:28 10:13:28 10:18:28 10:23:28 10:28:28 10:33:28 10:38:28 10:43:28 10:48:28 10:53:28 10:58:27 11:03:27 11:08:27 11:13:27 11:18:29 11:23:28 11:28:28 11:33:28 11:38:28 11:43:28 11:48:27 11:53:28 11:58:28 12:03:28 12:08:27 12:13:28 12:18:28 12:23:27 12:28:27 12:33:27 12:38:27 12:43:28 12:48:27 12:53:27 12:58:27 13:03:28 Temperature and RH CD Concentration (mg/l) 70.0 1700 PPM-Hr Cycle Data 2.50 60.0 2.00 50.0 40.0 1.50 30.0 1.00 20.0 10.0 0.50 0.0 0.00 RH Temp CD Concentration
Equipment Used 1 Minidox-M CD Gas Generator Control by PPM-Hrs 17 cu ft Isolator (2 glove) SGM Spore Strips ACD/6 bacillus atrophaeus (ATCC 9372) All BI s Stored at 45% RH SGM Releasat fast readout culturing media BI Challenge Fixture test fixture to mimic small gaps (0.185 [4.7mm]) Incubation at 37 Deg C BSC Scrubber (remove CD gas) RH Controller Using dry nitrogen to control isolator (45% & 55%) 8
Equipment Used Exhaust Aeration air supply CD Gas Sample 2 Glove Isolator CD Gas Inject Minidox-M CD Gas Generator 9
BI Placement RH Probe BI 1 (in sampler) Up High BI 2 (on shelf) Middle BI in BI Challenge Fixture BI 3 (on floor) Low 10
Chlorine Dioxide Generator Configuration Chlorine Dioxide Gas Generator and Control System Reagent Gas Gas Generating Cartridges Photometer Real time CD Gas measurement Relative Humidity Probe Isolator RH Control Box Gas Injection Nitrogen Cylinder
PPM-Hrs Explanation Standard CD Cycle is RH - 65% with 5 minutes of condition time CD Concentration - 1mg/L CD Exposure time 2 hrs PPM calculation for 1mg/L PPM = (mg/m3) (24.45) / Molecular Weight PPM = (mg/l) (1000) (24.45) / Molecular Weight CD ppm = (1.0mg/L) (1000L/M3) (24.45) / 67.5 CD ppm = 362.2 Exposure Contact Time (CT) Exposure CT = 362ppm * 2 hrs Exposure CT = 724 ppm-hrs 24.45 = volume (liters) of a mole (gram molecular weight) of a gas at 1 atmosphere and at 25 C.
Standard Runs 65 % RH, 720 ppm-hrs ppmhrs mg/l RH Condition Time 720 1 65 5 720 5 65 30 720 10 65 30 720 20 65 30 Results 0/3, 0/3, 0/3 (0/1, 0/1, 0/1) 0/3, 0/3, 0/3 (0/1, 0/1, 0/1) 0/3, 0/3, 1/3 (0/1, 0/1, 0,1) 0/3, 0/3, 0/3 (0/1, 0/1, 0/1) NOTE: 720 ppm-hrs is the standard CD cycle regardless of concentration 13 Results in parentheses are from BI Challenge Fixture
Results - 65 % RH ppmhrs mg/l RH Condition Time Results 450 1 65 5 0/3, 3/3, 3/3, 2/3 (N/A) 550 1 65 5 0/3, 1/3, 0/3, 2/3, 0/3, 0/3 (0/1, 0/1, 0/1, 1/1, 1/1, 0/1) 600 1 65 5 1/3, 0/3 (0/1, 0/1) 550 1 65 30 0/3, 0/3, 1/3, 3/3, 3/3 (0/1, 0/1, 1/1, 1/1, 0/1) 600 1 65 30 1/3, 0/3, 0/3, 1/3 (0/1, 1/1, 0/1, 1/1) 720 1 65 5 0/3, 0/3, 0/3 (0/1, 0/1, 0/1) NOTE: 720 ppm-hrs is the lower level for 6 SLR at 65% RH Results in parentheses are from BI Challenge Fixture 14
Results - 55 % RH ppmhrs mg/l RH Condition Time Results 550 5 55 30 3/3 (1/1) 850 1 55 5 2/3 (0/1) 925 1 55 5 0/3, 1/3, 1/3, 0/3, 0/3, 1/3, 0/3, 0/3 (0/1, 0/1, 0/1, 0/1, 0/1, 0/1, 0/1, 0/1) 1000 1 55 5 0/3, 0/3, 0/3 (0/1, 0/1, 0/1) 1400 1 55 5 0/3 (N/A) 2100 1 55 5 0/3 (0/1) NOTE: 1000 ppm-hrs is the lower level for 6 SLR at 55% RH Results in parentheses are from BI Challenge Fixture 15
Results - 45 % RH ppmhrs mg/l RH Condition Time 1400 1 45 5 1550 1 45 5 1700 1 45 5 Results 0/3, 1/3, 1/3, 1/4 (0/1, 0/1, 0/1, N/A) 0/3, 0/3, 0/3, 0/3 (0/1, 0/1 0/1, 0/1) 0/3, 0/3, 0/3, 0/3 (0/1, 0/1, 0/1, 0/1) 2100 1 45 5 0/3 (0/1) NOTE: 1550 ppm-hrs is the lower level for 6 SLR at 45% RH Results in parentheses are from BI Challenge Fixture 16
MRSA and VRE Data Standard Sporicidal Cycle Rooms RH - 65% with 5 minutes of condition time CD gas concentration of 1.0 mg/l Exposure - 120 minutes Overall exposure - 720 ppm-hrs demonstrates a 6 log reduction Staphylococcus aureus (MRSA) and Enterococcus faecium (VRE) RH - 65% with 30 minutes of condition time CD gas concentration of 0.2 mg/l Exposure - 45 minutes Overall exposure - 54 ppm-hrs demonstrates a 5 log reduction 17
Salmonella Data Standard Sporicidal Cycle Rooms RH - 65% with 5 minutes of condition time CD gas concentration of 1.0 mg/l Exposure - 120 minutes Overall exposure - 720 ppm-hrs demonstrates a 6 log reduction Salmonella typhimurium (ATCC 14028) RH - 65% with 30 minutes of condition time CD gas concentration of 0.3 mg/l 100 ppm-hrs had a 6.999 log reduction 200 ppm-hrs had a 7.01 log reduction 18
DIRT Data CD Gas penetration into Organic Load All 6 BI s Killed with 720 ppmhr cycle 19
Conclusions Does RH affect spore log reductions (SLR)?? YES (previous references Agalloco, 2008; Westphal, 2003; Whitney, 2003) Does concentration-time affect spore log reductions?? YES 720 PPM-Hrs is good for 6 SLR at 65% RH 1000 PPM-Hrs is good for SLR at 55% RH 1550 PPM-Hrs is good for 6 SLR at 45% RH 20
Prepared by: Mark A. Czarneski Director of Technology ClorDiSys Solutions, Inc www.clordisys.com PO Box 549 Lebanon, NJ 08833 Phone: 908-236-4100 Fax: 908-236-2222 e-mail: markczarneski@cloridsys.com 21
References: Agalloco, J., Carleton, P., & Frederick, J. (2008). Validation of pharmaceutical processes (3rd ed., p. 283). New York: Informa Healthcare USA Inc. Westphal, A. J., Price, P. B., Leighton, T. J., & Wheeler, K. E. (2003). Kinetics of size changes of individual Bacillus thuringiensis spores in response to changes in relative humidity. Proceedings of the National Academy of Sciences, 100(6), 3461-3466. Whitney, E. A. S., Beatty, M. E., Taylor, Jr., T. H., Weyant, R., Sobel, J., Arduino, M. J., et al. (2003). Inactivation of Bacillus anthracis spores. Emerging Infectious Diseases, 9(6), 623-627. Acknowledgements: Chris Ballard ClorDiSys Solutions, Inc. Dan Paznek, ClorDiSys Solutions, Inc. Tyler Mattson, ClorDiSys Solutions, Inc. 22