In the middle of 2024, the FDA published a final rule that revised certain agricultural water requirements in the Produce Safety Rule for pre-harvest agricultural water for non-sprout covered produce. 

The final rule establishes requirements for systems-based, pre-harvest agricultural water assessments for hazard identification and risk management decision-making. Covered farms that use pre-harvest agricultural water for covered produce (other than sprouts) are required to conduct agricultural water assessments once annually, and whenever a significant change occurs that increases the likelihood that a known or reasonably foreseeable hazard will be introduced into or onto produce or food contact surfaces.

As part of their pre-harvest agricultural water assessments, farms are required to evaluate certain factors that could impact produce safety as a result of the use of pre-harvest agricultural water.

For pre-harvest agricultural water requirements for non-sprout covered produce, the compliance dates are as follows:

April 7, 2025: Covered farms for which, on a rolling basis, the average annual monetary value of produce the farm sold during the previous 3-year period is more than $500,000. 

April 6, 2026: Covered farms for which, on a rolling basis, the average annual monetary value of produce the farm sold during the previous 3-year period is more than $250,000 but not more than $500,000 (small businesses).

April 5, 2027: Covered farms for which, on a rolling basis, the average annual monetary value of produce the farm sold during the previous 3-year period is more than $25,000 but no more than $250,000 (very small businesses).

Agricultural Water for Pre-Harvest Applications 

Some factors for evaluation of the quality of agricultural water include:

• Location and type of water source, i.e., is it ground or surface water?
• Type of water distribution system (e.g., open or closed to the environment)
• The degree to which the system is protected from sources of contamination (e.g., other users, animal impacts, adjacent and nearby land uses related to animal activity
• Agricultural water practices (e.g., application method such as sprinkler, spray, drip, furrow, flood, seepage irrigation
• Time interval between last direct application of agricultural water and harvest
• Crop characteristics (susceptibility of produce to adhesion or uptake of hazards)
• Environmental conditions (heavy rain, floods, air temperatures, sun, etc.
• Methods and results of testing

The final rule exempts covered farms from conducting a pre-harvest agricultural water assessment if they can demonstrate that their pre-harvest agricultural water meets certain requirements that apply to harvest and post-harvest water (microbial quality, testing requirements), is received from a public water system that meets requirements in the rule and is treated in accordance with standards outlined in the Produce Safety Rule, and is reasonably likely that the quality of the water being used as agricultural water will not change in storage or conveyance.

Looking Back: Ongoing E. coli/STEC Contamination of Pre-Harvest Water

Over the prior two decades, FE has reported repeated E. coli O157:H7/STEC (Shiga toxin-producing E. coli) contaminations in leafy greens, especially in lettuce and spinach from the two salad bowl growing regions in the U.S. for leafy greens: Coastal California and the Desert Southwest. Suspect over recent years is the issue of produce farms being located adjacent to CAFOs as former FDA Deputy Commissioner Michael Taylor described at the 2019 Food Safety Summit. This colocation may have been the cause of STEC outbreaks in leafy greens if they were irrigated with contaminated irrigation water.

To combat recurring food safety issues (see FE, May 4, 2010), the FDA had come up with a plan for 2020, called the “2020 Leafy Greens STEC Action Plan.” The FDA document outlined several steps in improving agricultural water safety, enhancing inspection and auditing, doing microbiological surveys for the presence of STEC, and improving supply chain communications in terms of track and trace. While there is a lot of emphasis on testing and data communications, the FDA paper also addressed geographical and land use issues, which are at the heart of the problem. E. coli O157:H7 doesn’t magically appear on produce; it comes from animal sources, primarily cattle — but goats, sheep and pigs can carry it as well.

Finally, a First in Treating Pre-Harvest Agricultural Water Approved by FDA and EPA

On November 4, 2024, FDA announced that a collaborative effort between government, academia and industry has led to the successful registration of the first antimicrobial treatment for pathogen reduction in pre-harvest agricultural water, a landmark achievement in enhancing food safety. A BioSafe Systems product, called SaniDate 12.0, was evaluated extensively over several years in collaboration with the University of Arizona Water Quality Specialist Dr. Channah Rock, and effectively combats foodborne pathogens like E. coli (STEC) and Salmonella in water used to grow and irrigate crops. It’s the first label amendment approved under a revised efficacy protocol designed by the FDA and EPA to ensure robust treatment options are available for agricultural use.

The registration was given to BioSafe Systems for its SaniDate 12.0. The chemical is approved by FDA and EPA to treat pre-harvest irrigation water to fight Salmonella enterica and E. coli STEC producing bacteria, commonly found in cattle farms that may border spinach and lettuce producing fields.

BioSafe Systems is not a new name to vegetable growers. “BioSafe Systems has endeavored to mitigate growers’ risks when it comes to preharvest food safety for years,” says Jay Sughroue Ph.D., BioSafe Systems, area manager for its Agriculture Division. “Contaminated irrigation water can compromise an operation and incite potential recalls. The most common culprits threatening consumers’ food safety are the foodborne bacterial pathogens Salmonella enterica, and Escherichia coli (E. coli), specifically the Shiga toxin-producing E. coli (STEC). When these harmful bacteria contaminate water sources used for irrigating crops, they can potentially lead to food safety recalls and inflict incredible damage on growers, the public’s health, and consumers’ trust in a brand.”

FE spoke with Sughroue to learn more about SaniDate and its application to pre-harvest irrigation water applications.

FE: What happened to lead to the development and application of SaniDate 12.0 to irrigation water in trenches? Was this primarily an EPA project?

Jay Sughroue: It was a joint effort between the FDA and the EPA along with key university researchers to establish a protocol for manufacturers to follow for registrations of irrigation water treatment chemistries for the control of E. coli O157:H7 and Salmonella enterica.

FE: How did BioSafe Systems get involved in finding a solution to this E. coli/produce problem? 

JS: BioSafe Systems has been working in post-harvest food safety for over 25 years with our products for both nonporous hard surfaces and wash waters disinfection and sanitization. When the leafy green industry in California and Arizona started to inquire about using PAA for irrigation water treatment around 2014, it was natural to take our experience from treating wash water inside the packing/processing facilities and apply it to the field. We began actively working with several universities on the proper dose and contact time to achieve adequate control/suppression of generic E. coli and coliforms (indicator organism) in irrigation water.

FE: Throughout the BioSafe press release, it discusses SaniDate 12.0 meeting EPA approval, but also meeting the required bacteria killing efficacy needed by FDA, in fact, a couple of logs more effective than FDA rules. How did BioSafe work with EPA and/or FDA to approve BioSafe as an effective solution to apply to agricultural water before irrigating? 

JS: Before the EPA released the “Efficacy Protocol for Reduction of Foodborne Bacteria in Preharvest Agricultural Water,” in April 2020, we were already testing our two major products with Dr. Channah Rock, water quality extension specialist/professor at the University of Arizona. Two years prior: in 2018, in large scale field trials for the reduction of indicator organisms (generic e. coli and coliforms) as well as non-virulent strains of E. coli and Salmonella. Once the EPA released the revised protocol in 2021, we began testing our products with both GLP and non-GLP labs to see what was the minimum concentration required to achieve the required 3-log reduction in both organisms as required in the efficacy protocol. 

FE: So the FDA announced this milestone achievement in November 2024. When did SaniDate 12.0 become available to produce farms? Are farms now using it? What have been the results?

JS: Public health could not wait for the FDA/EPA to establish the guidelines for treating irrigation water for human health pathogens and as a result leafy green growers and the industry came together and began treating irrigation water with known chemistries such as PAA and chlorine. Growers began using EPA approved products for the control and suppression of slime forming bacteria, algae and water molds in irrigation systems. We knew that if we could control slime forming bacteria, algae and water molds in irrigation water we could also control human health pathogens such as E. coli and Salmonella.

FE: Since SaniDate 12.0 can effectively control and reduce Shiga toxin-producing Escherichia coli (STEC), including O157:H7, and Salmonella enterica in preharvest irrigation water, is there a need to develop a solution that also includes Listeria Monocytogenes? If so, would those applications be primarily for post-harvest use and in the plant? Some plants reuse rinse water, so is it safe to assume that they test used water? (I’m thinking some of the cantaloupe Listeria recalls, where cantaloupes were either rinsed with dirty water or were not cleaned properly in the first place.)

JS: We already have EPA approved SaniDate products (SaniDate 5.0 and SaniDate 15.0) that are labeled for controlling Listeria Monocytogenes in post-harvest applications such as non-porous hard surfaces and wash waters. According to university water quality specialists, the FDA doesn’t have a body of knowledge related to Listeria in irrigation water and therefore dropped it from the testing requirements in the revised FDA 2021 protocol. To my knowledge Listeria is not routinely found in irrigation water and is primarily found as biofilm that forms on hard surfaces such as inside a packing/processing facility and on harvest equipment. All water that is used inside packing/processing facilities are treated with different types of chemistries such as PAA and chlorine, and are monitored with specialized probes that measure the concentration of these chemistries to ensure the proper effective concentration levels are maintained for keeping the processing waters free of these pathogens.

The cantaloupe recall/food safety issue was because old equipment was used to pack and sort the cantaloupe and it was not properly cleaned to eliminate biofilm buildup and as a result cross contamination occurred.

FE: What is SaniDate WTO?

JS: SaniDate WTO is the younger brother to SaniDate 12.0. Both SaniDate WTO and SaniDate 12.0 are based on the same peroxyacetic acid (PAA) chemistry. SaniDate 12.0 is stronger and only approved for conventional production, whereas SaniDate WTO is the first EPA-registered product to reduce and control foodborne bacterial pathogens in agricultural irrigation water for organic production.

With this recent EPA registration, SaniDate WTO gives organic growers another incentive to convert from their current chlorine treatment to a sustainable chemistry with superior efficacy in controlling foodborne bacterial pathogens in irrigation water that won’t contribute additional sodium and chloride to their soils.

FE: What’s the future look like for improving food safety of leafy greens?

JS: Leafy green growers and processors are continuing to improve their operations to increase food safety in all aspects from field to fork, which includes using EPA registered products to control human health pathogens in irrigation water. University researchers are diligently making progress to better understand the conditions in which vegetables and fruit are more prone to become contaminated with harmful bacteria, which will lead to better ways to mitigate the risk of growing crops for human competition in non-sterile environments.