Outbreaks in fresh produce, while tragic for victims, nevertheless can have a positive outcome if we can learn how to better prevent them, or at least reduce their occurrence. This four part series will discuss the current produce outbreaks in cantaloupes, cucumbers, celery and strawberries and analyze the information that is known, with the intention of improving our food safety systems.
Recent breakthrough events
While the fresh produce industry in the US continues its food safety efforts, pathogens have recently broken through our safety net in diverse products such as cantaloupes, cucumbers, celery, and strawberries. These events have highlighted our immediate need to strengthen food safety systems in the entire fresh produce industry.
The fresh produce industry utilizes Good Agricultural Practices (GAP), Current Good Manufacturing Practices (cGMP), and Hazard Analysis Critical Control Point (HACCP) systems based primarily on guidance from The US Food and Drug Administration (FDA). Some producers of high risk products bolster these efforts with commodity specific guidelines developed by industry. Firms also utilize microbial sampling programs for water, environments and products, and implement traceability programs. Various agencies may have jurisdiction at the produce/processor level of the fresh produce industry, but most of the growing, packing and transportation of produce remains without consistent government oversight. The Food Safety Modernization Act gives FDA broad new authority to tighten regulations in the fresh produce industry, but the agency has not yet effectively exercised these new powers.
Dynamic Industry Based Food Safety Programs
In the absence of mandatory food safety rules in fresh produce, the industry has developed its own voluntary program for produce safety, including its own standards. These programs consist of science-based standards, policies and procedures, training, sampling, and the maintenance of records to support GAP, GMP and HACCP. The major buyers of fresh produce (retailers such as Costco, Wal-Mart, Publix, Kroger, among many others), insist upon the verification of these safety measures using ongoing third party, second party and self-audits. Government agencies, producers and buyers randomly test products for pathogens, and the industry conducts voluntary product recalls when pathogens are found.
These programs should not be static; preventive measures taken by the industry should change and adapt as we learn more about how pathogens contaminate, proliferate and survive in the chain of production from the farm to the consumer.
While it is not possible to know the route of transmission in every situation, we should still analyze foodborne illness outbreaks. What we do know about pathogens can be just as important as what we do not know. Achieving the ideal of a farm to fork food safety net requires a dynamic response from the entire supply chain to the problem of contamination.
Salmonella Outbreak in Cantaloupe
On March 22, 2011 the Del Monte Company issued a limited voluntary recall of cantaloupes from its Asunción Mita, Guatemala farm, saying they have the potential to be contaminated with Salmonella Panama. Over the course of the ensuing outbreak, authorities identified 20 victims in 10 states linked to this farm by epidemiological investigative techniques.
In this outbreak, as in many others, investigators failed to isolate the causative agent from a suspect melon. This prompted two law suits, one against the FDA, and another against a state epidemiologist. Del Monte asserts that the epidemiological approach used to associate cases with vehicles was flawed; while investigators contend that such a rare serotype could not be caused by anything other than exposure to a common vehicle. FDA points out that almost all victims of illness purchased cantaloupe from stores supplied by the Del Monte farm in the relative time period.
Del Monte, as part of its case against FDA, argues that its food safety program would have prevented such occurrences. Third party audit findings from April, 2011 showed a high degree of conformance with industry standards by this facility, but auditors also found that some sanitation controls needed to be improved. Results of third party audits of the packing facility in question suggested two important corrections:
- · Covering an exposed sewage ditch
- · Incorporation of daily cleaning and sanitation of the dump tank
In July of 2011, FDA banned products from the Asunción Mita facility, concluding that they were produced under insanitary conditions and that they likely contain Salmonella. FDA recently lifted this ban.
In its import alert, FDA recommends that based on previous experience, its food safety personnel should evaluate the following risk factors:
- · Safety of water used in irrigation, packing and cooling;
- · Manure use and bio-solids, animal management;
- · Worker health and hygiene;
- · Sanitary facilities in field and packing house, disposal of sewage and silage;
- · Maintenance program for cleaning, sanitizing equipment;
- · Field and packing facility sanitation;
- · Transportation;
- · Steps taken to identify and correct insanitary conditions.
Lessons from this event
At this time FDA has not made public its findings from the inspection of the Asunción Mita packinghouse, but some information about sanitary conditions have been reported by third party auditors. A reference for this can be found in a report by the Florida Center for Investigative Reporting.
Covering an exposed sewage ditch
It is not perfectly clear what the source of this sewage is, whether it is “black water”, meaning waste water from toilets and hand sinks, or “gray water” meaning spent water from other sources (wash flume water, floor drains, drainage from refrigeration, etc.).
Regardless of its source, such wastewater is a potential source of pathogens, and facilities are required to dispose of it safely.
In many regions, we rely upon sewage disposal rules written by health agencies for the collection, transference, treatment and disposal of wastewater. Ideally, there is an enclosed piping system to convey the wastewater to a treatment system before disposal of the effluent, such as into the soil in subsurface septic systems. Such effluent can also be discharged directly into a sanitary sewer if one is available, or treated in an onsite sewage treatment system before discharge into a flowing body of water.
In no case should untreated wastewater, or "sewage" as FDA puts it, from a produce operation be disposed of in a ditch, onto the surface of the ground, or discharged into a body of water.
There may be no rules for wastewater discharge in some agricultural operations, or operations may be loosely regulated. This is often the case in the developing world, or in remote rural locations. In such cases, decisions about what to do with wastewater are left up to plant personnel who may lack knowledge of sanitary wastewater disposal. Unsanitary wastewater discharges and lack of compliance with environmental regulations can unfortunately be found in some produce facilities.
Opponents of government regulation should be aware that the imposition of consistent sanitary waste disposal methods are a hallmark of public health controls. Where these are enforced, environmental exposures to sewage are greatly minimized. Where there is no regulation, such hazards are likely to be forgotten or simply not addressed and create problems.
Incorporation of daily cleaning and sanitation of the dump tank
Not all produce is washed before being packed; in this case the facility did wash its melons. The common practice of field-packing, meaning packing directly into boxes or other containers as the final unit-packaging, is common with several commodities, and has some serious concerns.
In certain cases, makeshift washing in the field occurs, such as in barns using tanks of water. In many farming areas water is a precious commodity and is reused. A tank of water used to rinse produce in a barn may remain for an entire day without changing. Thousands of individual pieces of vegetables may be so exposed to pathogens if even one unit has contaminants. To say that on-farm washing systems like this are antiquated is an understatement.
It is a mistake to assume that water used for field packed product is even potable under the meaning of the law. The US Environmental Protection Agency (EPA) provides the standards for potability of water. Because there is yet no clear government regulations as to the application of potability standards to water used for washing produce, the industry relies on periodic microbial testing of water and the available research and advice of experts. Usually, the produce industry relies on tests for the coliform bacterial indicator group to gauge microbial quality. Where a satisfactory result of < 1 CFU in a 100 ml sample is obtained, the water is considered potable.
However, wash water is rarely tested “in process”, the operator assuming that periodic testing of the water source and treatment is all that is necessary. This is often the case where packinghouse operations use washing systems consisting of sprays or flumes.
The third party audit findings for this operation indicate that the facility in question “dumped” its products into a tank of water (dump tank), and that the frequencies for changing this water and cleaning the tank were questionable.
It is common to see confusion on the part of operators of produce packing facilities as to how to control the safety of process water. What the industry has done in past years to satisfy buyer demand for a product that “looks clean” may cause an exposure if re-circulated water systems are not properly tested, treated, cleaned and maintained.
We must improve our controls for process water, but questions remain: How to do we treat such water? What antimicrobial to use? And how do we test its efficacy? And very importantly, what do we do about improvised washing methods often used in field packing?
Listeria Outbreak in Cantaloupe
On September 14, 2011, FDA issued a press release to announce that Jensen Farms, a Colorado operation, issued a voluntary recall of its Rocky Ford-brand cantaloupes after being linked to a multistate outbreak of Listerosis.
At this time there have been 21 deaths and 109 people have been sickened in the outbreak — including the 21 dead — in 23 states from California to the East Coast
(To be continued in Part 2 of this four-part series).