Clean Room Protection & Biosecurity: Dry vs. Wet Foot Bath Mats (2024)

INTRODUCTION

The use of biosecurity footpans, also known as footbath mats, at critical entrance points into and throughout an agricultural production facility is again front-and-center in lieu of the 2022 agricultural disease status within the U.S. Complicating this issue even further is a continued raw materials supply-chain shortage plaguing nearly all global business sectors, including the chemical disinfectant, pharmaceutical, and materials manufacturing industries. Coupled with labor recruitment, training, and retention challenges also facing crop production and food production sectors, more than ever 2022 was a year to reflect on internal processes and procedures and how well the standard best biosecurity management practices are holding up to (employee execution) compliance, profitability, and true protection against crop and food safety pathogens.

The footpan is actually a very odd piece of our business in agricultural production (sold by most agricultural suppliers)... and not very many employees (if any) view the footpan as a welcomed, utilitarian, and standard “every day” part of protocol impacting movement onto and within farms, offices, greenhouses, feed mills, and processing plants. At best it slows things down just a little and adds (nearly negligible) cost to crop production, and at worst it feels like a waste of time and money to use properly.

Using footpans (and for most biosecurity protocols and materials, in general) often feels a lot like buying insurance; it simply operates in the background of your operation, without your thinking about it too often, and you hope it is ready, paid for and executed, and actually works in the rare case you might need it (to actually work properly)... but you really hope you never need it at all.

This disconnect between the actual proper set-up, use, and enforcement of biosecurity is basically due to two things happening simultaneously:

Clean Room Protection & Biosecurity: Dry vs. Wet Foot Bath Mats (1)

  1. The desired outcome of biosecurity is that nothing at all happens, and

  2. The culture of biosecurity (like establishing a culture of safety within a company) usually lacks “teeth”, often taking a back seat to more pressing matters of day-to-day disease prevention and management, executing standard daily protocols with the labor available that day, and always keeping a keen eye on opportunities to either make things simpler or cheaper.

This last piece can be the catalyst for re-thinking the footpan for your operation; simple, cost-effective, and working the best to manage diverse pathogen challenges facing agricultural managers and crop production supervisors throughout the agricultural industry in the U.S.

THE LIMITATIONS OF (SEEMINGLY) ANY LIQUID FOOTPAN DISINFECTANT

While biosecurity is a 24-7 year-round combination of materials and a process, certain weather and times of year make this process difficult... depending on the placement of the footpan. Despite the best efforts of agricultural production staff and farm owners to identify the most suitable location for footpans, they are universally very poorly maintained and mostly ignored. When the footpan is small enough, personnel will often step over or around the pan to avoid stepping into the pan. This is most often a problem for wet footpans containing diluted disinfectant that can leak into footwear thatmay be damaged (holes), causing skin irritation or the discomfort of wet socks for an entire shift. Jumping over can also be dangerous for employees, potentially causing slip-and-fall scenarios.

Wet footpans containing diluted disinfectant have previously been shown to have a very short lifespan as an effective tool to kill pathogens on footwear. In a study performed at an agricultural facility by Dr. Bob Owens et al. (2006), the authors demonstrated two very distinct pieces of data, showing liquid footpans are:

  1. quickly inactivated after only a few uses (Figure 1)

  2. this inactivation seemed mostly indifferent as to the chemistry applied to the footpan (quat vs. phenol; Figure 2).

Fresh SolutionAfter 3 Hours
Active% Change in Bacterial Count% Change in Bacterial Count
Phenol-45.8130.5
Quat-57.573.3
Water87.244.8

Figure 1. Total bacteria counts from shoe swabs. Phenol and quat liquids kill bacteria in fresh disinfectant, but after only 3 hours, bacteria actually increased on shoe swabs, suggesting non-protection of the deactivated disinfectant liquid footpans.

Fresh SolutionAfter 3 Hours
Active

Before>After 25 exposures

Increase in Bacteria

Before>After 25 exposures

Increase in Bacteria

Phenol36 → TNTCTNTC → TNTC
Quat1 → 12185 → TNTC
Water19 → TNTCTNTC → TNTC

Figure 2. Total bacteria counts in the disinfectant dilution liquid. Phenol and quat liquids are inactivated, allowing for bacteria to survive and/or grow in the footpan liquid after only 25 uses. After the solution sits for 3 hours, bacteria thrive in the organic material dilutions of quat and phenol.

The data is not only important because it shows that the organic material introduced into footpans inactivates the disinfectant solution, but also that the dirty, deactivated footpan can quickly become an actual reservoir to spread microbes after stepping into the liquid solution. As a follow-up to this data, the authors decided to test dry footpan materials and their ability to reduce microbial counts on boots.

At the agricultural facility prior to the greenhouse (break room entrance), employees’ boots were swabbed prior to and then after stepping into either liquid phenol or quat disinfectant, or dry chlorine bleach powder (alone or with detergent) for 5 to 10 seconds. The results of the “real world” trial are summarized in Figure 3. One important note is the poorest performance of phenol, the chemistry often touted as being “more resistant to high organic load,” tolerant of dirty surfaces when compared to other conventional disinfectants like quats, oxidizers, and alcohols (CFSPH 2021).

Active% Change in Bacterial Count% Change in Bacterial Count
Dry Bleach + Soap-92.614 Days
Dry Bleach Powder-98.114 Days
Phenol (Liquid)10.8<2 Hours
Quat (Liquid)-23.6<2 Hours

Figure 3. Reduction in bacterial counts on agricultural employees’ boots after 5-10 second contact time with liquid and dry antimicrobials. Average residual lifespan estimated (calculated) based on available chemistry (molarity) and deactivation by organic load from all data (Owen and Lawlor, 2006).

Liquid disinfectant footpans have another few disadvantages besides being irritating on wet socks (leaky boots), slippery on spongy footbath mats, and rapid deactivation compared to dry products; wet footpans in agricultural operations quickly transfer organic material into solution, creating a visible messy and murky soup that no professional would ever encourage their employees to step into. This further impacts the “culture of biosecurity” problem:

How do agricultural health professionals encourage, support, and enforce biosecurity protocols that they themselves cannot technically verify and demonstrate as visibly “making sense” (i.e., not a murky filthy footpan) to crop growers and farm management staff?

DRY BLEACH CAN BE CHALLENGING

While dry bleach proved itself to outperform liquid disinfectant solutions in footpans, this powdered chlorine has a few drawbacks that have created a challenge to becoming a clear replacement for biosecurity liquids. Off-gassing of chlorine is a notorious characteristic of di- and trichlor-based solid bleach powders. The chlorine released from the powder into the immediate space surrounding the dry bleach footpan is not only potentially annoying to employees (due to the smell), but also can oxidize/rust metals in that area, including switches, controllers, and fixtures. When placed into footpans in very wet areas, some dry bleach products can become “slick”, causing a potential hazard for areas around high water usage on smooth floors, or complicated by melted snow and heavy rain at doorways.

A QUAT-FREE & BLEACH-FREE ALTERNATIVE; A 2022 GRANULAR SPIN ON OLD LIQUID CHEMISTRY

Organic acids have been well described as having diverse antimicrobial activity against diverse bacteria and fungi (Martin and Maris, 2005), with acetic acid and lactic acid having one of the greatest efficacies in organic loads (Cherrington et al., 1992). Their even more powerful synergy with the simple combination with hydrogen peroxide (like tech grade Khemical Hydrogen Peroxide, 34%) in a simple mixture was described by the same authors seven years later (Martin and Maris, 2012). When the chemistries of hydrogen peroxide and select organic acids combine, pathogen intervention is peracetic acid (or “PAA”; as seen in the equation below).

Clean Room Protection & Biosecurity: Dry vs. Wet Foot Bath Mats (2)

Peracetic acid (like PeraShield 15%) is normally (conventionally) formed in a liquid environment, the two reactants being added to a vessel and with a little help from an acid catalyst forms PAA. The formation of this molecule in liquid was industrialized for manufacturing prior to WWII, but has only been in commercial use for the last 50 years. In 2021, the EPA granted approval for pathogen claims for the world’s first solid peracetic acid granule invented and commercialized by MORR, Inc. (Harvey and Howarth, 2018). This specialized hygroscopic formulation uses a somewhat similar (but unique) approach to create biocidal PAA from the moisture-activated powder without the need for vinegar (also known as acetic acid).

The Peraguard AH granule offered to customers for the first time in 2022 breaks down into innocuous by-products, like soda ash, glycerin, water, CO2, and oxygen. The lack of vinegar means that there is no strong smell (like liquid PAA) or offgassing like bleach powder, and the formula is not slippery or dusty. Further, there is no known bacterial resistance to PAA, and with the solid granule in a footpan, you only need to add more material to the pan as it contacts footwear and is carried out of the pan. The continuous release of PAA over time gives a strong initial kill and long-lasting protection.

When compared to other EPA-approved footpan powders, Peraguard AH has economic advantages and is easy to use (“add to, no need to throw out and replace”). The simplicity of not having to empty and then clean dirty liquid footpans... or throw away old, expired powder after a few weeks... means better compliance, and a stronger culture of easy, enforceable biosecurity within agricultural health leadership, crop growers, and farm management staff. If you can simply see the granules still there in the footpan (and admittedly the pan is also not full of dried organic material), then the moisture-activated Peraguard AH is still available to help control pathogens on boots into and within your agricultural facility.

Biosecurity in a footpan has never been so economical, effective, and easy to accomplish.

Relevant products:

SaniDate 5.0

Prime Source Ultra Germicidal Bleach

Khemical Sodium Hypochlorite 12.5% - Liquichlor Bleach

References:

  1. Owen, R.L. and Lawlor, J. (2006). “A Novel Approach to Foot Dipping”, Hubbard Presentation (https://vdocument.in/1-a-novel-approach-to-foot-dipping-robert-l-owen-and-john-lawlor.html)

  2. CFSPH - Center for Food Security and Public Health (2021). “Characteristics of Selected Disinfectants.”(https://www.cfsph.iastate.edu/Disinfection/Assets/characteristics-of-selected-disinfectants.pdf)

  3. Martin, H., and Maris, P. (2005). “An assessment of the bactericidal and fungicidal efficacy of seventeen mineral and organic acids on bacterial and fungal food industry contaminants.” Sciences Des Aliments. 25, 105-127.

  4. Cherrington, C.A., Allen, V., and Hinton, M. (1992). “The influence of temperature and organic matter on the bactericidal activity of short-chain organic acids on Salmonellas.” J. Appl. Bacteriol. 72, 500-503.

  5. Martin, H., and Maris, P. (2012). “Synergism between hydrogen peroxide and seventeen acids against six bacterial strains”. J. Appl. Microbiol. 113, 578-590.

  6. Harvey, M.S., and Howarth, J.N. (issued June 26, 2018). “Methods and compositions for the generation of peracetic acid on site at the point-of-use.” U.S. Patent #10,004,230.

Clean Room Protection & Biosecurity: Dry vs. Wet Foot Bath Mats (2024)
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