3 Legionella Proactive Protocol 2008 Introduction/RefresherSystems that may Harbor Legionella and What to DoRisk CategoryLegionella Testing RequirementsFrequency of Cleaning/DisinfectionAction Levels and Associated Response and Cleaning StepsCooling Tower Design Best PracticeMaintenance Considerations
4 Legionella Refresher 2011Legionella SourcesLegionella ControlPlanning and Record Keeping
6 Legionella Bacteria Source of Legionella Conditions for growth Pervasive organismSoil derivedConditions for growth68 - 122 F (20 - 50 C)pH 6-8Stagnant watersA nutrient sourceBiofilms, organicsSediments, deposits
7 Factors Determining the Risk of Contracting the Disease A source of LegionellaFavorable growth conditionsAqueous aerosols less than or equal to 5 micronsSufficient organisms to cause infectionSusceptible individual
8 Systems Promoting Growth Cooling towersEvaporative condensersHot and cold water systemsTaps and showerheadsHumidifiers and air washersSpa and whirlpool bathsDecorative fountainsAll systems noted are at a potential risk for transmitting Legionella bacteria because they have the potential to meet all the criteria noted in slide # 5, i.e.,A source of Legionella organismOptimum conditions for growthAqueous aerosol for transmissionSufficient organisms to cause infectionTransmission to susceptible individual
9 Field Study on Biofilm Growth PhaseTimeColonization15 MinutesGrowth Detection2 DaysBiofilm Formation(Exopolymer/ Minimum Biofouling)5 DaysMaximum Biofilm Growth(8 – 10 Cells Thick)14 DaysFully Mature Biofilm Matrix31 – 40 DaysIt is the Legionella harbored in biofilms that are of most concern as they be in the virlent state whithin a host cell (higher life forms such as protozoan, omeba etc) and amplify in numbers and be protected. So biofilm control is most important.
10 Cyclic Operation and Biofilms AOC supports bofilm growthFlow and AOC supply stopped results in biofilm starvation and detachment- 90% in 24 hours- 80% in 12 hours- 60% in 10 hours- 40% in 8 hoursContinuous flow without AOC achieves 90% biofilm detachment in 3 daysTaken from “Hypothesis for the Role of Nutrient Starvation in Biofilm Detachment” Montana State University, Applied & Enviormental Microbiology, Dec2004, pages 7418 to 7425.21 days to develop a good biofilm, 10^9 CFU/cm^2, 300 micro meters thickFood (AOC) is glucose.AOC is more important than the bulk water bacterial count (ie CFU/ml), <10ppb AOC little to no growth, < 20ppb AOC the target to avoid excessive biofilms.2 week biofilm growth is about 1.4 to 2.7 X 10^5 CFU/cm^2
11 Effects of Cooling System Dynamics – cfu/ml Same Day Comparative Samples (Example System Treated with Continuous Oxidant and Slug Feed of Glutaraldehyde Once Per Week)Aerobic BacteriaFungiAnaerobic BacteriaHigherLife FormsFlowing Bulk Water Basin Chip Scale<101600101,000,000NoYesBasin Sludge3,500,00020Dead Head (off) Plate/Frame XER40010,000Slip StreamBy-pass (10%) Plate/Frame
13 Microbiological Control Capability Efficacious biocides selectionBiodispersant supplement for biofilmEffective application for required concentration and contact timeSystem dynamics (ART, T½) and volumeDedicated automated feed of microbiocidesFeedback control Loop (ORP, self verifying feed pumps)Pre-conditioning/sterilizationPreseason start-upIdle restartsSterilization/hyper chlorination at the summer peakEnd of season shutdown
14 Microbiological Control Additives of Choice OxidationBleach (CSW 20)Sodium Bromide/Bleach (Drewbrom)BCDMH (Biosperse 261T)Chlorine DioxideNon OxidantsGlutaraldehyde 1º (Biosperse 254/255)Isothiazolin 2º (Biosperse 250)BiodispersantsNonionic Surfactants (Drewsperse 739)Protein cross linking/cationic surfactant blend (Performax 405)Anionic surfactants (Drewsperse 7211)The use of Ozone, Ultra Violet Light and or Copper/Silver Producing Electrolysis in combination with a biocide are also acceptable. Their use alone, without chemicals is not effective in large water systems accept potable water systems within the building. Care must be taken with the use of Copper/Silver applications in systems where carbon steel metals are also used, otherwise localized galvanic corrosion maybe incurred by the carbon steel components.
15 Legionella Control with Non-Oxidizing Biocides Chemical CompoundActive Concentration mg/ℓContact TimeGlutaraldehyde1 HourIsothiazolin6 Hours2 Bromo-2-Nitro Propane-1,3, diol (BNPD)2540024 Hours60 MinutesDithiocarbamatesDi-bromo-nitrilo-propionamide (DBNPA)4 - 82 HoursNote: System potential contaminants and operational pH must be checked for compatibility with the non-oxidizing biocideThe amount of biocide added via slug feeding must be higher than noted above in order to attain the residual noted above at the end of the required contact time.
16 Continuous Oxidant Feed Protocol Continuous feed for chlorine, bromine, BCDMH or stabilized bromineDosage:Recommended FAH and/or equivalent mV ORP with a minimum requirement of a measurable residual FAHFor higher risk systems increase FAH residual as needed to control CFU level and biofilmFeed a supplemental organic biocide*Recommend biocide be glutaraldehyde or an alternate biocide fed with biodispersantFeed once per week or as needed to control biofilmThis slide highlights biocide requirements when continuous oxidant feed option is applied.Glutaraldehyde is recommended due to its excellent ability to strip biofilm as well as compatibility with oxidizing microbiocides. In the event glutaraldehyde can not be applied at a facility, alternative organic biocides can be applied. Selection is dependent on Relative Population Density (RPD) study results.ORP is oxidation-reduction potential, the measure of a water’s oxidation energy.*Alternative choices of non-oxidizing biocide should be based on Relative Population Density (RPD) lab results
17 Intermittent Oxidant Feed Protocol Chlorine, bromine, BCDMH or stabilized bromineMinimum dosage: Hold FAH and/or equivalent mV ORP for a minimum of 2 hours each dayFeed alternating supplemental organic biocides*Recommend one biocide be glutaraldehyde or an alternate biocide fed with biodispersantFeed an additional compatible organic biocide*Alternate feed once per week*Alternative choices of non-oxidizing biocide should be based on RPD results
20 Action Levels Immediate response to positive test results On-line treatment requires a minimum of 14 days to produce resultsUnrealistic a system could be totally Legionella free
21 Direct Testing of Legionella Frequency ConsiderationPrior to peak summer sterilization (i.e. beginning/mid August) for seasonally operated HVAC or after a sterilization.After cleaning of a confirmed cooling tower sourced outbreakIf a confirmed outbreak has occurred in the area (≤3 km minimum)Three times per year of 24/7 Industrial process cooling systems of higher risk noted earlier
23 Implications of the Need for Biocide Improvements Action Days After Action 2 CompletedNon oxidizers Review Dosing Schedule and Amount Used vs. Contact Time (Feed/Bleed Issues)Oxidizer – Semi-Continuous; Frequency and Duration for 1 to 2 ppm FAC Applied. Minimum 0.5 – 1.0 ppm 4hours/24hoursOxidizer – Continuous; 0.2 to 0.5 ppm FAC go to 0.5 – 1.0 ppm FACRetest within 3-5 Days
24 Implications of the Need for Biocide Improvements Action Level Days After Action Level 3 CompletedNon oxidizer Program May Require Oxidant Use At 1/Week in Summer and ½ Weeks Winter at 1-2 ppm FAC for 1 Hour CT (i.e. 2 Hour Run Time)Semi-Continuous Oxidizer may require either / or both non oxidizer or Biodispersant Once per WeekContinuous Oxidizer at 1-2 ppm FAC may require either / or both Non-Oxidizer or Biodispersant once per WeekNon Oxidizer or Biodispersant Addition Maybe Required Every System Retention Time (Vol/BD Loss)May Require Online Clean Within 30 DaysRetest Within 3-5 Days
25 Implications of the Need for Biocide Improvement Action Level 5 – 14 Days After Action Level 4 CompletedOn-line Clean within 7 Days of This StateBiodispersant Plus ≥ 5 ppm FAC forORBiodispersant Plus ≥ 25 ppm FAC for 2 HoursBiosdispersant Plus ≥ 50 ppm for 1 HourTest 3-7 Days Latter – Poor Results Repeat or Go to Off-line Approach
26 Implications of the Need for Biocide Improvement Special NotesAction Levels Are a Forward ProgressionUpon Attaining Steady State Correction Move Backwards on the Action Levels Assuring No Return to Control State LossIt is not Unusual to have to Repeat Online or Offline Cleans as Previous Suppressed Biofilms, Sludge and Muds have now been Conditioned/ Loosened for Release to the Bulk Water
27 OSHA/Wisconsin Protocol Confirmed Cooling Tower Source of OutbreakTurn off tower fansShock dose chlorine donor to 50 ppm FACAdd BiodispersantHold 10 ppm FAC for 24 hoursDrain cooling system and repeat steps 2 - 4Inspect for biofilms. If present, drain and mechanically clean.
29 Frequency of Cleaning/Disinfection Immediately prior to new system being commissionedIf the system has been out of use for one month or longerIf the system has been modified, entered or disturbed in such a way to lead to contaminationIf the cleanliness of the system is in any doubtIf microbiological monitoring indicates there is a problemAt least twice a year
30 Frequency of Cleaning/Disinfection Preconditioning/DisinfectionEnd of Operating Season2 per Year Minimum for 24/7 Systems (4)Disinfection OnlyAt Peak Seasonal DemandOccurrence of Outbreaks in the AreaUpon System Restarts of ≤ 4 weeks Idleness (≥ 3 Days?)’Idle System of 1 Month or More to be Drained
31 Sterilization Only Frequency During restart of idle/stagnant towers, condensers, heat exchangersSeasonal restart of HVAC system, which was preconditioned and sterilized the end of the previous seasonPeak of summer cooling demand(i.e. beginning of August).Known outbreaks in the areaBiological dip slide counts exceed 105 – 106 CFU/ml. Visible slime (i.e. biofilm) present.
32 Implications of the Need for Biocide Improvement Off-line CleaningPre Conditioning withBlowdown to ½ COCBiodispersant and Non Oxidizer for 24 HoursHyper ChlorinationpH 7.5 – 8.0Biodispersant≥ 10 ppm FAC for 24 hoursDrain and FlushPost Conditioning of ≥ 10 ppm FAC for 1 HourTest 3-7 Days Latter – Poor Results Repeat or Go to Wisconsin Protocol
34 Total System Approach: Five Areas of Activity and Performance Comprehensive system assessment Intensive microbiological treatment program Sterilization and cleaning Monitoring and controlDocumentationAll Information is Available in Previous Presentations 03, 06, 08Contact CTM or AHWT for the presentations and additional information.
35 System Assessment System survey In-depth survey of system mechanical layout and operating conditionsUtilizes established protocol, ex BSRIA- Building Services Research Institute Assoc. (UK)Identify, evaluate and rank specific factors associated with potential for microbiological growth and LegionellaMechanical and chemicalDetermine risk minimization action plansA formal system assessment is the first component of our Best Practices program and is an essential activity for Legionella risk management.The system assessment is a “fee for service” survey that fully reviews mechanical, environmental, operational, and chemical treatment program parameters and evaluates the factors associated with the potential for microbiological growth and Legionella. The system survey evaluates the entire system in terms of critical factors and identifies mechanical and operational practices that should be modified to enhance system cleanliness.The system survey follows an established, detailed protocol that is based on our decades of experiences in England (UK), using their regulated Approved Code of Practices (ACOP) guidelines and Australia and New Zealand where risk management is mandatory and regulated. In addition to global experiences, Drew Industrial’s Legionella risk management program is based on recommendations by CTI, ASHRAE, CDC, OSHA, and others.The outcome of this assessment is a plan to minimize overall microbiological growth, minimize aerosol production and distribution from water systems, and recommendations to improve overall system cleanliness. Implementing the plan reduces the opportunity for Legionella growth and spread.Drew Industrial can perform system assessments using trained internal resources or can use outside experts to perform these surveys and risk assessments. (Contact Joanne Kuchinski in Boonton for more information.)
36 Documentation Why Document? When a pneumonia outbreak occurs in a facility it allows for:Speed in identifying the source for eradication purposes, removing a potential and continual threat. After all it may not be cooling system derived.Clinical micro biologists and physicians to select appropriate antibiotics, dosages and monitor the progress without the presence of further stressors.
37 Documentation To name a few: Simplified line drawing of the cooling system and all equipment, dead legs cross over lines, chemical feed points/lines/control, system volume, recirculation make-up and blowdown ratesKey water test results/dateChlorides or conductivity for cycles of concentration assessmentMake-up, blowdown water meter readingsFAH and/or ORP for Halogen concentrationBiological Tests – CFU/ml; CFU/cm2Start, end and expiry dates of dip slide lots for bio testing
38 Documentation To name a few: Chemical pump and timer settings Biocide usageStart-up/shutdown and other application logs of preconditioning/sterilization and sterilization onlyInspection/observations for slimes, muds, algae in cooling tower and on coupons and what was done to improveContingency plans procedures, and results/check offs when performed.
39 “Ideal System” Water flow is continuous No dead legs or stagnant conditionsBasin and deck protected from sunNo evidence of sludge, debris, algaeDrift eliminators installed, functioningNo evidence of aerosols, driftSystem not near health care, aged, residential facilityLow number of people potentially exposedHalogen usedBiodispersant/bio-dispersing biocide usedComprehensive water treatment programAutomated biocide and chemical dosingContinuous automated monitoring, controlThis slide summarizes ideal situations yielding the lowest potential for growth and exposure.
40 High Risk Facilities Hospitals Retirement Homes Long-term and chronic care facilitiesPublic facilitiesOfficesMallsHotelsProcess cooling systems that have the potential for:Aerosol spray cooling – automotiveProcess contaminationCPI/HPIFood/Beverages
41 Cooling System Susceptibility High airborne dirt load potential(utilization of side-stream filtration)Nearby constructionLack of ground coverings with aggregate materials or vegetationHigh nutrient load potentialProcess side inleakageTower near chemical, food or vehicle exhaust
42 Cooling System Susceptibility Cooling tower air discharge near proximity to fresh air intakes or open windows of building, and/or outdoor population(i.e. ground level).
43 Cooling System Susceptibility No operation or intermittent operation of equipment while wet:Drain if stagnant > 1 monthIdle - rotate weekly or install 5 – 10% slip stream flowDead legs or seasonal cross-over linesRemove them orLoop them with 5 – 10% slip stream flowClose shut-off valves at flowing supply and drain the remainder of the branch system and equipment
45 Survey of Process Risk HIGH LOW Humididifer/Fogger Aerosol Producing ProcessMisters, AtomizersAir WashersDecorative Fountains and WaterfallsWhirl PoolsHot TubsShower HeadsPotable Water Hot/coldCooling Towers/ Evaporative Condensers Risk increases with Location (i.e. Grounds Levels, Near Air Intakes/Windows), Local Ground Cover, Air Contamination/ Proximity to Exhaust See C.T.I. Design and Maintenance ConsiderationSludge/Settled Solids>⅛″ - ¼″Non-VisibleTemperature35ºC (95ºF)To 46ºC (115ºF)<20ºC (68ºF)>50ºC (124ºF)Biological Activity>104 CFU/ml>105 CFU/cm2Presence of Higher life forms (OMEBA, PROTOZOA, ALGAE, MOLD, FUNGUS).≤103 CFU/ml≤104 CFU/cm2No Higher Life Forms
46 Factors Contributing to Legionella Health Risks in Cooling Systems BiofilmTemperature and pHOrganicContaminationAerosolsAlgae and ProtozoaScale and CorrosionStagnantWaterCondition of Drift EliminatorsHigh LevelsOf Heterotrophs(i.e. CFU/ml)Exposure to SunlightIntermittentOperationTowerRepairPresence ofLegionellaQualityBio-ControlProgramProximityTo Populations
47 TABLE 2 – COOLING SYSTEM SUSCEPTIBILITY TO LEGIONELLA RISKS ISSUECONDITIONCORRECTIVE MEASURECOOLING TOWER (C.T.) LOCATIONGROUND LEVEL AND/OR DIRECT EXPOSURE TO POPULATIONC.T. AIR DISCHARGE NEAR BUILDING FRESH AIR INTAKEC.T. AIR DISCHARGE NEAR WINDOWS IN BUILDINGTHAT OPENNONE A DESIGN CONSTRAINSNONE, A DESIGN CONSTRAINT, USE THERMOGRAPHY TO DETECT DISTANCE OF AIR TRAVEL WRT INTAKE LOCATIONNONE, A DESIGN CONSTRAINT, OR FIX WINDOWS CLOSED, USE THERMOGRAPHY TO DETECT DISTANCE OF AIR TRAVEL WRT WINDOW LOCATION.MAKE-UPUNCLARIFIED, UNFILTERED, NO DISINFECTIONPRETREATMENT EFFECTIVELY OR GO TO POTABLE WATER SOURCEHIGH AIRBORNE DIRT LOADNEAR BY CONSTRUCTION AND OR EXCAVATIONLACK OF GROUND COVERTEMPORARY, STEP-UP BIO TREATMENT APPLICATIONS, USE SIDE STREAM FILTRATIONCOVER EXPOSED EARTH WITH AGGREGATE MATERIALS OR VEGETATION, USE SIDE STREAM FILTRATION (SEE ATTACHMENT I)WATER FLOWINTERMITTENT LEADING TO STAGNATION, BIOFILMS, BIO-SEDIMENTS, ANAEROBIC CONDITIONSDRAIN IF STAGNATION > 1 MONTHROTATE EQUIPMENT WEEKLY WITH MILD STERILIZATION (5 PPM FAH, 6 HOURS) UPON RESTARTSINSTALL 5-10% SLIP STREAM FLOW PROVIDED COOLING WATER IS LOW IN SUSPENDED SOLIDS (I.E., ≤ 5NTU) OR SIDE STREAM FILTERING IS PRESENT (I.E. ≤ 25 NTU THEORETICAL).
48 TABLE 2 – COOLING SYSTEM SUSCEPTIBILITY TO LEGIONELLA RISKS ISSUECONDITIONCORRECTIVE MEASUREDEAD LEGS, SUPPLY/RETURN HEADER DEAD HEADS, SEASONAL CROSSOVER LINESBIOFILMS, BIO-SEDIMENTS, ANAEROBIC CONDITIONSREMOVE DEAD LEGS OR BLOWDOWN (HIGH VELOCITY FLUSH) EVERY 5 TO 7 DAYSLOOP SUPPLY/RETURN HEADERS WITH 5-10% SLIP STREAM FLOW PROVIDED COOLING WATER LOW IN SUSPENDED SOLIDS OR BLOWDOWN EVERY 5 -7 DAYS.SEASONAL CROSSOVER LINES AND EQUIPMENT. PROVIDE 5-10% SLIP STREAM FLOW PROVIDED COOLING WATER IS LOW IN SUSPENDED SOLIDS OR INSTALL ISOLATION VALVE AT THE FLOWING LINE TAKE OFF WITH A BLOCK AND BLEED VALUE ARRANGEMENT AND DRAIN THE SEASONAL LINE AND EQUIPMENTHIGH NUTRIENT LOAD POTENTIALPROCESS INLEAKAGEEXHAUSTING AIR/GASES FROM CHEMICAL OR FOOD PROCESSING (VOC’S) AND VEHICLES NEAR COOLING TOWER INTAKESEMPLOY DETECTION AND CONTINGENCY MITIGATION METHODS AS DONE FOR TRADITIONAL CHEMICAL TREATMENT PROGRAMSREDIRECT EXHAUSTING AIR/GASESDIRECT SUNLIGHT ABSORPTION BY COOLING TOWERBASINUPPER DISTRIBUTION DECKNONE, A DESIGN CONSTRAINTENCLOSE WETTED EXPOSED AREAS WITH HINGED COVERS THAT ALLOW FOR ACCESS AND INSPECTION
49 TABLE 2 – COOLING SYSTEM SUSCEPTIBILITY TO LEGIONELLA RISKS ISSUECONDITIONCORRECTIVE MEASUREHIGH DRIFT AND AEROSOLS IN COOLING TOWER AIR EXHAUSTDRIFT ELIMINATORS MISSING ORIMPROPERLY INSTALLEDOLD, LOW EFFICIENCY DRIFTELIMINATORS PRESENTCHECK DRIFT ELIMINATORS FOR PRESENCE AND CORRECT INSTALLATION. REFIT REPLACE BROKEN ELIMINATORSUPGRADE TO HIGHER EFFICIENCY DRIFT ELIMINATORSCOOLING TOWER INSPECTION OF FILL, ELIMINATORS, BASIN, DISTRIBUTION DECKVISIBLE BIOFILMS, ALGAE, SLUDGE, DEBRISANAEROBIC/SEPTIC SMELLING MUDS, H2S RELEASE UPON HC ADDITIONAPPLY AGGRESSIVE CLEAN STERILIZATION PRECONDITIONING/FLUSH OF RECIRCULATION SYSTEMPAST/PRESENT BIOLOGICAL CONTROLBIOFILMS PRESENT ON DRYING COUPONS (I.E. SHEEN TO TANNISH/BROWN COLOR DEVELOPMENT)>105 CFU/ML H.B.C.> 106 CFU/CM2 H.B.C.APPLY ONLINE MODERATE PRECONDITIONING STERILIZATIONHALOGEN IN USE WITHOUT BIODISPERSANTNOT EFFECTIVE IN MINIMIZING BIOFILMSSEE TABLE 4 FOUR OXIDANT LEVEL CONTROL AND TABLE 5 FOR ACCEPTABLE BIODISPERSANT DOSAGESNON-OXIDIZERS IN USE NOT BASED ON GLUTARALDEHYDE, ISOTHIAZOLINE, BROMONITROPROPANEDIOL, OR DIBROMONITRILOPROPIONAMIDE CHEMISTRYLITTLE TO NO EFFICACY TOWARD LEGIONELLA CONTROLSEE TABLE 6 FOR CORRECT NON-OXIDIZER, DOSAGE AND CONTACT TIME REQUIRED FOR LEGIONELLA CONTROL
50 Site Survey Pretreatment/Precleaning Need Assessment
51 Precleaning Determination DEPOSIT ANALYSIS<10% LOI<40% MOISTURE<104 CFU/CM2<105 CFU/GMNO SRB’S, IRB’S, MOLDCOUPONS TUBERCLATED WITH HARD SINTERED CORROSION PRODUCT AND SHINY SILVER TUBERCLE BASEHIGH % IRON>10% LOI>40% MOISTURE>105 CFU/CM2>106 CFU/GMPOSITIVE SRB’S, IRB’S MOLDCOUPONS AND SURFACES NOT SEVERELY TUBERCULATED, BASE NOT SHINY SILVER>10% LOI>40% MOISTURE>105 CFU/CM2>106 CFU/GMPOSITIVE SRB’S, IRB’S, MOLDCOUPONS/SURFACES HIGHLY TUBERCULATED AND SHINY SILVER BASELOW % IRONOFF LINE CLEANING OF AFFECTED EXCHANGERS FOR TUBERCLE REMOVAL AND REPASSIVATION, IMPROVEMENT IN CORROSION CONTROL PROGRAM REQUIRED.ON LINE BIOFILM CLEAN-UP AND STIFLING OF TUBERCLES – PLUG APPARENT POROSITY, MIXED BIO/CORROSION FOULINGON LINE BIOFILM CLEAN-UP, BIOFOULING ONLY
52 Monitoring and Inspection Inspection for visible slime or sludge'sDecksMist eliminatorsFillSumpsCorrosion or biofilm coupons
53 Monitoring and Inspection TestingBulk water dip slidesPrior to non-oxidizing biocide additionMinimum once per weekTarget ≤ 104 CFU/mlCoupon surfaces - if availablePrior to non-oxidizer and/or biodispersant additionEvery 30 to 60 days, but be consistentTarget ≤105 CFU/cm2
54 Preventive Actions Inspect and Test Domestic Waters Fountains Spas Air Handling UnitsHumidifying/Dehumidifying Equipment/CoilsCooling Towers
55 Other Water SystemsTreat and Maintain Similar to Cooling Tower ProtocolsFountains and WaterfallsFiltrationDrain RegularlyMisters/Atomizers, Humidifiers, Air WashersCoils, Spray Bars, Sumps, Mist EliminatorsPre/Post Air FiltrationBleed/DrainClean/DisinfectSludge RemovalUV – Air Space
56 Biofilms Biofilms Don’t Just Harbour Legionella, They: Restrict Air FlowRestrict Water FlowReduce Heat TransferReduce Heat RejectionInduce Localized CorrosionBiological ControlHigher Life Forms – NoneBacteria CFU/ml <104, > 105 Do somethingBacteria CFU/cm2 <105, >106 Do something
57 Preventive Action Use your Biocides in a Prudent Manner And Remember Sterility Does Not Exist Except in Higher Life Forms