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Cleaning and Sanitizing on the Farm for COVID - 19

By Annalisa Hultberg, Extension Educator, On-Farm Food Safety 
(with input from Natalie Hoidal, University of Minnesota Extension and Don Stoeckel, Produce Safety Alliance)

Agricultural producers are working diligently to prepare their farms to plant, harvest and sell their food crops in a safe and healthy manner during the COVID-19 pandemic. While the most important way to minimize the spread of the SARS-Co-V-2 virus is via physical distancing and minimizing person-to-person contact (CDC), cleaning and sanitizing of surfaces on the farm like frequently touched surfaces, tools, and equipment is also important. This post is about sanitizing those surfaces, not about hand sanitizers or soaps for hands.

The following are a set of recommendations relating to what we know about cleaning and sanitizing to control the spread of the virus. Use this information to guide your farm's policies and guidelines and to prioritize your actions this growing season.

1) What do we know about how the virus is transmitted?

Remember: there is currently no evidence that the virus that causes COVID-19 is spread through food or food packaging (CDC, FDA). The virus is respiratory and the primary mode of transmission is via droplets that are spread between people when they sneeze, cough, or breathe near each other. The viral particles are carried on the droplets that are expelled from an infected person and land in the mucous membranes (eyes, nose or mouth) of another person and travel to the lungs, where they cause the infection. (WHO, COVID-19 and Food Safety: guidance for food businesses)

Source: USA Today

Transfer may also happen via surfaces when an infected person coughs or sneezes onto a surface like a doorknob, handle, phone, their hand or any other surface. Another person can then transfer those particles via their hands to their eyes, nose or mouth, where the infection can occur.

Even though surfaces are not thought to be the primary route of transmission of the virus (CDC), it is still very important to clean and sanitize surfaces to minimize the transmission of the virus via these surfaces. Since other respiratory viruses spread via contaminated surfaces, it seems likely that this one can too. Carriers of the disease can be asymptomatic for days before they show signs of illness, which makes it even more important to clean and sanitize surfaces to prevent these carriers from inadvertently spreading the virus.

2) How should I clean and sanitize on the farm for COVID-19?

The good news is is that many farms already have robust cleaning and sanitizing routines for their food contact surfaces. Sanitizing for COVID-19 might not be significantly different from those current procedures, with the addition of extra attention to "high-touch" surfaces. Develop and follow a preventative schedule of cleaning and sanitizing your farm's tools, equipment, food contact surfaces and high-touch surfaces to minimize the spread of the virus. 

Think about the goals for your cleaning and sanitizing based on two different categories of risk:

1.) Before any known contamination: If you have no reason to think that you have a known COVID-19 case on the farm, your basic preventative cleaning and sanitizing routine should be sufficient using the sanitizing hard surfaces rate on the label of the product you are using. Clean and then sanitize these surfaces on the farm daily, or more if needed or if you have a large crew or a large number of visitors. 

Some "high-touch" surfaces that you should sanitize at least daily. You might think of many more for your operation. 
  • Door handles
  • Steering wheels
  • Cooler handles
  • Phones
  • Light switches
  • Toilet handles
  • Faucet handles
  • Buttons, pads and touch screens used by staff or volunteers 
  • Watering wands, shared tools and any on-and-off switches 
Other surfaces include food contact surfaces like the following. These should be cleaned and sanitized daily when in use:
  • Sorting tables
  • Harvest totes and buckets
  • Brush washers or other large equipment
  • CSA totes
  • Scales
  • Tools, clippers and knives

2.) If a known case of COVID-19 on the farm: Clean and disinfect all surfaces, especially any that were touched by the sick person, using the higher disinfection rate as per the label. (If you use the disinfection rate on food contact surfaces you must follow with a rinse step.) Follow all guidance from the CDC and the Minnesota Department of Health about the steps to take, including disinfection, in the event of a confirmed COVID-19 illness on the farm.

3.) Clean and sanitize correctly

Before a surface can be sanitized, it must be cleaned. Sanitizer is meant to be the last step in the process. If sprayed on a visibly dirty surface, sanitizer will not work. You must pre-clean the surface.

Here are the steps:
  1. Remove all visible debris from a surface with a broom or water
  2. Scrub surface with a detergent like Dawn or another product to break down fats and carbohydrates that might be present
  3. Rinse with potable water
  4. Spray with a sanitizing agent (letting it sit for as long as indicated on the label)
  5. Air dry
These steps should be completed for all visibly dirty surfaces. If there is a surface like a doorknob that is not dirty, simply spraying with a sanitizer or wiping with a disinfecting wipe is likely sufficient. As a precaution, all surfaces should be washed occasionally with soap and water in addition to being sprayed with a sanitizer.

4) What is the difference between cleaning, sanitizing and disinfection?

As per the CDC and definitions from the EPA

Cleaning: Removes dirt and debris from a surface using a detergent (soap) and water. This doesn't necessarily kill germs, but removes them.
Sanitizing: The use of a chemical to lower the number of germs on a surface by 99.999% after proper cleaning.
Disinfection: The use of a chemical to kill all germs on a surface or object after proper cleaning. This uses a higher concentration of chemical sanitizer, and/or a longer wet contact time.

5.) What sanitizers are effective against the virus that causes COVID-19?

There are not yet any products specifically labeled for use on the SARS-CoV-2 virus, though many are currently being researched for effectiveness.

In the meantime, the EPA has provided the definitive  "List N"  which is the list of approximately 370 disinfectants  that are approved for use against SARS-CoV-2 virus because they are effective against other human coronaviruses or harder to kill organisms. You can search this list for a product. The best way to use this tool is to search the EPA registration number on a label, since products go by many names in the marketplace. You can also search by active ingredient.

Household bleach: Ultra Clorox Regular Brand bleach (6.0% sodium hypochlorite product) is approved for use against the virus. The hard surface sanitizing rate is 200 ppm, or about 1 T per gallon. The label indicates 2 minutes wet contact time.

VigorOx SP-15: VigorOx SP-15 (15.0% peroxyacetic acid and 10.0% hydrogen peroxide product) is approved for use against the virus and OMRI- approved for organically certified operations.  The label says that the surface sanitizing rate is 3.1 oz. per 50 gallon of water (85 ppm of PAA) with a wet contact time of 1 minute. 

Sanidate 5.0Sanidate 5.0 (5.3% peroxyacetic acid and 23.0% hydrogen peroxide product) is a OMRI-approved disinfectant product made by BioSafe Systems. Sanidate 5.0 is not currently listed on the EPA's List N. However, BioSafe recently released a press release stating that Sanidate 5.0 has  been tested and shown to be effective against human coronaviruses at a rate of 1 Fl oz per gallon, or about 400-450 ppm with a 10 minute wet contact time.  The company is currently applying for a supplemental label to include the efficacy on human coronaviruses, and when that approval is granted it will be listed on the List N. Here is the Sanidate 5.0 label.

For any PAA disinfectant, test the ppm with tester strips to ensure proper mixing. These PAA tester strips have a range from 1-1000, allowing you to measure higher concentrations

Note: Inclusion in this list does not mean endorsement from the University of Minnesota.

Remember - surfaces are not thought to be the primary mode of transmission for the SARS-Co-V-2 virus. Close human-to-human contact and droplet transmission through breathing, coughing and sneezing is the most common way the virus is spread. However regular cleaning and sanitizing, focusing on those "high-touch" surfaces that many people touch is a prudent step to reduce risk and the possibility of transmitting viral particles among your staff, crew and potentially to customers.

For more information:

Institute for Food Safety at Cornell University  Up-to-date compilation of information and guidance to the food industry relating to COVID-19, including many published scientific articles

A Guide to Cleaning, Sanitizing and Disinfecting for Produce Farms (University of Vermont). Excellent summary of the cleaning, sanitizing and disinfection steps for growers related to COVID-19.

COVID-19 and Food Safety (North Carolina State University)  Food safety portal housing many factsheets and other informational resources with the current science related to COVID-19.

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