Cleaning is the removal of unwanted matter, including macro soil we can see: dirt, debris, and spills; and micro soil: harmful bacteria, viruses, spores, dust particles, and chemical substances below the threshold of human perception. Micro soils, with their ability to enter the human body, often have a major impact on health, and require critical emphasis during cleaning. How do you know when you have effectively removed these micro-soils that can endanger human health? In a word: measurement.
Following is an overview of three types of devices that can help validate a hygienic cleaning program focused on microbial and fungal micro-soil removal. Each device detects ‘markers' that identify a certain micro-contaminant, for example, ATP testers determine the presence of adenosine triphosphate which is present in organic matter (bacteria, yeast, mold, food residue, etc.) to determine overall bio-soiling; biodetectors determine or utilize the presence of antibodies, enzymes, DNA, and other components of particular living organisms; and mold detectors detect fungal enzymes as indicators of the presence of mold.
ATP is the most widely recognized and accessible marker, since it enables the broadest assessment of the presence of organic soils. According to Hygiena, a leading manufacturer of ATP testing devices:
'ATP (adenosine triphosphate) is present in … organic material, and is the universal unit [or currency] of energy used in all living cells. ATP is produced and/or broken down in metabolic processes in all living systems. Processes such as photosynthesis in plants, muscle contraction in humans, respiration in fungi and fermentation in yeast are all driven by ATP. Therefore, most foods and microbial cells will contain some level of naturally occurring ATP. The [ATP device] uses bioluminescence to detect residual ATP as an indicator of surface cleanliness. The presence of ATP on a surface indicates … the presence of [bio]contamination, including food residue, allergens and/or bacteria … [and] potential for the surface to support bacterial growth.'
ATP results are inconsistent, however, when testing surfaces of organic nature (e.g., unfinished wood) because those surfaces have varying innate levels of ATP. 'Background ATP levels can vary among building materials,' said Dr. Gene Cole, Professor of Environmental Health Sciences, Brigham Young University, 'thus the method must be researched according to a specific cleaning approach, the materials and surfaces to be cleaned, and the desired outcome (i.e. acceptability), in order to enhance interpretation.'
Tiled restrooms, stainless steel and tiled foodservice areas, and laminated desktops as found in schools, are ideal for ATP testing since they have no inherent ATP to skew readings.
According to Forensic Sanitarian, Dr. Robert W. Powitz, who holds a Masters in Public Health, with a specialty in institutional practice, and a PhD in environmental health from the University of Minnesota: 'The more I use ATP testing in my work, and the more I explain its operational capabilities and limitations to my clients, the greater is our collective level of comfort in using it to define and set reasonable guidelines and standards for cleanliness.'
ATP-based and/or Petri-film based cleaning protocols are currently in development by several industry consultants and KaiScience, supported by Kaivac (a leading backer of cleaning industry research), and will include:
1. Flat Surface Cleaning (FSC) Protocol (Above Floor)
2. Hard Floor Cleaning (HFC) Protocol
3. Uneven Surface Cleaning (USC) Protocol (Above Floor)
Preliminary results data based on the initial tested cleaning protocols are encouraging:
ATP Counts - Reported in Relative Light Units (RLUs)
Flat Surface Cleaning (FSC) Protocol (Above Floor)
Note: The FSC Protocol (using KaiFly, manufactured by Kaivac, Hamilton OH) was compared to MF (standard microfiber towel) in cleaning a flat surface (table).
FSC Protocol vs. Microfiber (MF) Towel
• FSC Protocol reduced a 6936 RLU count to 28 RLUs
• MF Towel reduced a 6907 RLU count to 768 RLUs
Hard Floor Cleaning (HFC) Protocol
Note: The HFC Protocol (using a spray-and-vac machine, manufactured by Kaivac, Hamilton OH) was compared to MF (standard microfiber mop).
HFC Protocol vs. Microfiber (MF) Mop
• HFC Protocol reduced a 7844 RLU count to 27 RLUs
• MF Mop reduced a 7267 RLU count to 1479 RLUs
Petri Film Counts – Reported in Colony Forming Units (CFUs)
Uneven Surface Cleaning (USC) Protocol (Above Floor)
Note: The USC Protocol (using KaiWipes, manufactured by Kaivac, Hamilton OH) was compared to standard cleaning Cloths.
Petri film was used to test for CFUs (colony forming units). The bacterial counts in CFUs for the USC Protocol vs. Cloths (both using identical disinfectant):
• Average CFU/ sq in after cleaning was 1.8 for USC vs. 6.3 for Cloth (Cloth left 3.5 times more bacteria than USC.)
FSC, HFC and USC protocols all show significant after-cleaning reductions in contamination compared to traditional methods, with labor savings. Other protocol data is being gathered.
Hand-held ATP meters enable on site results monitoring within minutes of completion of cleaning, and provide a more effective way to assess cleanliness than visual inspection; an important factor in sensitive environments such as schools and hospitals. Hospital Infection magazine (published by The Hospital Infection Society) stated in 2000:
'A four-part study assessing cleanliness on up to 113 environmental surfaces in an operating theatre and a hospital ward was reported. Surfaces were assessed visually, using microbiological methods and ATP bioluminescence … Using published microbiological and ATP specifications, 70 and 76% of … sites were unacceptable after cleaning. Visual assessment was a poor indicator of cleaning efficacy with only 18% considered unacceptable…'
Professor Mike Wren, biomedical scientist in clinical microbiology, University College London Hospital said: 'Some of the most useful indicators of true cleanliness are ATP bioluminescence measurements…'
For the above reasons, ATP is a very promising marker for validating cleaningeffectiveness. ATP devices are also becoming increasingly affordable, with costs for hand-held units and kits starting at less than $1,000.
Biodetectors can detect specific germs, allergens and other organisms using ‘biological recognition'. These units range in size from desktop sized to hand-held, and use a variety of collection methods. The devices can use antibodies, living bacteria, single-celled organisms or tissues of higher organisms to detect the presence of unwanted substances based on a biological reaction. For example, if living cells inserted in the device react to certain antibodies, the biodetector can identify the specific bio-contaminant. Results can be delivered within 30-90 minutes.
Biodetectors developed to thwart bioterrorism may prove useful to the cleaning industry. These fall into three categories: those detecting a DNA sequence or protein that identifies the contaminant; living cells that react to specific agents and produce a measurable response; and mass spectrometry units that identify chemical components by molecular mass and cross-match them with biological agents of known molecular mass.
Portable DNA detection devices can now prepare and test samples within a very short time. The units basically break open bacterial spores and extract their DNA to identify the organism like a virtual 'laboratory on a microchip'. Procedures that used to take six hours in a lab can be done in the field in perhaps an hour or less. Northwestern University has developed a DNA-based biochip for identifying pathogenic microorganisms. Other units are being designed for anthrax identification.
The Autonomous Pathogen Detection System, or APDS, monitors the air like a smoke detector, and can detect and identify bacteria, viruses, and toxic substances. Costs and expertise required for most of these devices remain prohibitive for cleaning validation purposes (they were mainly designed for the military and medical sectors), but prices are expected to fall, and ease-of-use improve, as demand grows and biodetector technology advances.
Mold detectors are hand-held portable devices that detect fungal enzymes to determine total fungal biomass. Though the units cannot differentiate between types of mold, they can accurately determine on site within one hour the presence of fungi, and the effectiveness of mold remediation on surfaces including wood, grout, and various building materials.
'Our experience with [a mold detector] as the final clearance methodology for HVAC and mold remediation has been excellent… [it] documents the … efforts of our technicians,' said Tim Herbert, of Air Purification Specialists, Inc.
Mold detectors and test kits can be initially costly ($7,000+ each), but are especially useful for mold remediation verification, and can recoup costs over time (e.g., according to MycoMeter, a leading maker of mold detectors, 100 samples, charged at $75/sample, can generate fees sufficient to pay for the equipment purchase and kit supplies.)
According to Gene Cole: 'Comparative research is necessary to identify optimum cleaning effectiveness measurement methods for specific target markers across different environments, materials and surfaces, and applications. Such research, conducted in a cooperative mode of effort, will serve to define the many aspects of ‘clean', and help to establish consensus standards of care for ‘cleaning effectiveness' within the industry.'
In short, science now provides us with technology-assisted ‘eyesight' to detect generally invisible micro-soil, then remove it, and prove it. This helps us realize cleaning's ultimate purpose and potential – to protect people from unseen environmental harm.
Allen Rathey is the principal of the Healthy Facilities Institute (HFI), director of the Indoor Wellness Council (IWC), and author of articles about best practices in cleaning and indoor environmental management.
*The Healthy Facilities Institute (HFI) and the Indoor Wellness Council (IWC) do not endorse products.