By William Mitchell, Taylor O’Bannon and Michelle Danyluk
Biosolids, sometimes referred to as sewage sludge, are a primarily organic solid product produced by wastewater treatment processes. These organic solids are often used as an inexpensive soil amendment to enhance soil quality.
KNOW THE RULES AND RISKS
The Food Safety Modernization Act (FSMA) Produce Safety Rule (PSR) prohibits the use of human waste in any form, except the use of treated biosolids. To be used legally, biosolids must meet one of the two classes: Class A or Class B, and they must meet the Environmental Protection Agency’s (EPA) standards for pathogen and vector attraction reduction. The PSR allows for Class A biosolids to be used without restrictions on timing of harvest and application, while harvest cannot occur for 30 days after Class B biosolids are applied for tree fruits.
In Florida, biosolids application is regulated by the Florida Department of Environmental Protection. All land application sites in Florida are required to be enrolled in the Florida Department of Agriculture and Consumer Services Best Management Practices Program. Not only are there specific rules for application of Class A and Class B biosolids in Florida, but there are also county and site specific requirements and restrictions that may apply. It’s important to consult local regulations to ensure full compliance with both food safety and environmental standards before use. More information about use in Florida is available here.
While regulations may allow for biosolid use, there are still food-safety risks associated with use and storage of large quantities on the farm. The EPA regulations for Class A biosolids allows for <3 MPN of Salmonella per 4 grams (0.14 oz.) of total solids. Class B biosolids must meet a lower threshold.
While biosolids are treated to significantly reduce pathogens, it is important to remember that pathogens like Salmonella have not been completely eliminated. Caution to prevent potential cross contamination should be used when storing and applying biosolids, especially near groves in close proximity to harvest and near areas where post-harvest activities occur.
While biosolid use is allowed in the PSR, and may be allowed by local regulations, many food-safety audits do not allow for the use of human waste or biosolids. Before using biosolids, make sure it is allowable within your audit scheme. Many commercial fertilizers use biosolids as fillers so it might be worth double-checking the ingredients of your fertilizer with your supplier.
BIOSOLID BEST PRACTICES
Best practices for applying biosolids include:
- The materials used are compliant with federal, state and local requirements as well as with your audit scheme.
- Application records are kept which include: the type of biosolid, treatment classification, supplier certification and date and method of application.
- Materials are not applied in a way that allows for contact with the harvestable portion of the citrus crop or allows for potential contamination via runoff or drift.
- Adequate time intervals between biosolid application and harvest are maintained. Even though citrus is a tree fruit with a reduced likelihood of contact, risk-based decision-making should still be documented to demonstrate that no reasonably foreseeable hazards exist from the use of biosolids.
- Dropped produce or produce in contact with the ground is not harvested.
ADDITIONAL RESOURCES
More information about biosolids and the FSMA Produce Safety Rule can be found on the FDA Biological Soil Amendments of Animal Origin Fact Sheet and the EPA Biosolids Website.
On-Farm Readiness Reviews (OFRRs) are a valuable resource for growers looking to ensure their practices meet FSMA requirements. To request an OFRR, visit www.fdacs.gov/OFRR. Contact UFFoodSafety@ifas.ufl.edu with additional questions.
William Mitchell is an education and training specialist, Taylor O’Bannon is a state food safety Extension agent, and Michelle Danyluk is a professor — all with the University of Florida Institute of Food and Agricultural Sciences.
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