FDA Reopens the Raw Manure Debate

On March 12, the FDA released a new risk assessment examining human illness linked to produce grown in fields treated with untreated biological soil amendments of animal origin, including raw manure. The agency said the assessment evaluated how pathogens such as Salmonella, STEC O157:H7, and STEC non-O157 can survive, move through the farm environment, and ultimately reach consumers through contaminated produce. The findings are intended to inform future policy on standards for the use of untreated manure and similar amendments in produce production. 

This is a highly technical issue, but its practical importance is obvious. Raw manure has long sat in an awkward space between traditional farming practice and modern food-safety expectations. Farmers value it as a soil input, yet regulators worry about microbial risk. The FDA’s central conclusion was that extending the time between manure application and harvest significantly reduces pathogen levels on produce at harvest, though the strength of that effect varies by pathogen type, manure type, regional conditions, and starting contamination levels. That matters because it gives regulators a stronger scientific basis for decisions that had previously been postponed. 

The release is also notable because it revives unfinished business from more than a decade ago. FDA proposed a nine-month waiting period in 2013, but after criticism and requests for more science, it did not finalize that requirement. Instead, the final produce safety rule left the issue open pending further research. This new assessment suggests the agency is now closer to turning a reserved regulatory question into a real standard. For growers, that could mean tighter harvest intervals and more defined compliance obligations. For food-safety advocates, it is evidence that the agency is finally filling in one of the more important gaps in produce regulation. Either way, March 12 marked a meaningful shift: FDA is no longer just saying more science is needed. It is starting to act on the science it has.