The United States has one of the safest food supplies in the world, and it is the implementation of Hazard Analysis and Critical Control Points (HACCP) programs in several sectors of the food production industry that has made this a reality. 

HACCP programs require detailed and comprehensive identification of potential hazards that are “reasonably likely to occur.” Prior to January 4, 2011, the mandate of HACCP has only been applied to certain sectors of the food industry. On that date, however, the passage of the Food Safety Modernization Act directed the US Food and Drug Administration (FDA) to oversee implementation of risk-based food safety controls industry-wide.  The produce industry was singled out as being of particular concern in that legislation due to the number of food safety incidents in recent years that have involved produce commodities.

In recent years, there have been numerous recalls and illness outbreaks involving E. coli 0157:H7 or Salmonella traced back to lettuce or spinach greens.  There have been a number of other incidents involving previously-unseen occurrences of Salmonella in tomatoes, peppers and most recently in papayas.  The American consumer has come to believe that E. coli 0157:H7 is associated with beef, and that Salmonella is associated with poultry products. So how, then, can these organisms occur in vegetable and fruit products?

HACCP teaches an important lesson: process control is best achieved by implementing controls all the way back to the origins of the raw materials.  Managing the quality of the finished product poses greater challenges when the quality of the raw materials is not managed.  With all produce, the natural microbial load is expected to be in the range of six to nine logs (millions to hundreds of millions of counts per gram of product).  Random contamination of products can potentially result from heavy rainfall, from unsanitary handling by farm workers or use of soiled harvesting equipment, and from the fecal matter of mammals that visit the farm fields (E. coli, E. coli 0157:H7, and fecal streptococci) and from passing birds (Salmonella).  Naturally occurring hazards cannot be eliminated at the farm, but processing should address possible fecal contamination from the field with sufficient, validated washing processes to eliminate this hazard.  

The other potential sources of contamination at the farm are can and must be controlled -  namely, runoff water from property adjacent to the farm; irrigation and processing water quality, and the quality of products such as fertilizers or compost that are used to grow crops to maturity.  In one recent illness outbreak traced back to spinach, the US Food and Drug Administration (FDA) has identified water quality as a potential / probable vehicle of contamination. (see http://www.cidrap.umn.edu/cidrap/content/fs/food-disease/news/oct1306ecoli.html and http://www.indybay.org/newsitems/2006/09/24/18313586.php.  Speaking in general terms, this is of significant concern because contaminated surface water results in groundwater contamination. Some scientists have suggested that the use of untreated surface water, or wellwater from shallow wells, can lead to systemic contamination of crops. There is at least the potential for water-borne contamination to enter through damage to the surface of the product in the field. The use of improperly or inadequately processed compost presents the same opportunities for  contamination of crops. No amount of washing and sanitizing can eliminate bacterial contamination that has found its way beneath the outer surface of the product. Regardless of the reasons for which only certain types of produce seem to account for the outbreaks from each organism of concern, poor irrigation water quality increases the potential for any fruit or vegetable commodity to become contaminated with biological or chemical hazards that may be found in non-potable water.

The U.S. Environmental Protection Agency (EPA) has identified numerous microbiological and chemical potential contaminants in potable water. http://www.epa.gov/safewater/mcl.html#listmcl). Microbiologically, these may include coliform bacteria, Shigella, enteric viruses such as Norovirus and Norwalk, and parasites such as Cryptosporidium and Giardia. Chemically, the potential contaminants can include heavy metals, pesticides, herbicides, and a host of other organic chemicals.  Public potable water producers are required by law to address many of these potential contaminants in their testing plans on some predetermined schedule.

A well-equipped, diversified laboratory can analyze for a wide variety of analyses for contaminants in potable water.  While testing specifically for coliform bacteria is an easy method and a significant indicator of the quality of potable water, this analysis does not provide a complete representation of the water quality used for agricultural purposes.  To limit the scope of testing of irrigation water to only coliform bacteria analyses, especially if the testing is performed infrequently, risks overlooking other, existing microbiological or chemical hazards.  

It must be noted that testing water for E. coli with an “Absent” result does not assure the absence of pathogenic E. coli 0157:H7 or other strains (collectively known as Shiga Toxin-producing E. coli, or STECs). The STEC’s are bio-chemically different from other E. coli, and are not detected in analyses for “normal”, biotype I E. coli.  It is also critical to note that microbiological contamination is not uniformly distributed – rather, it is randomly distributed, and sampling plans must properly address this fact.  If there were ever a place in the food chain where simple changes could have a significant impact, water quality is such a place.

For fruits and vegetables, the quality of water required by Good Agricultural Process (GAP) for irrigation must be seen as a HACCP control.  Cooking kills bacteria, but this is not an option for products intended to be consumed raw.  Potential hazards must be carefully reviewed at the farm in the same way they would be in the processing facility.  The risk of contamination of farmland by surface runoff water from adjoining areas must be carefully assessed, and appropriate control measures must be taken. Irrigation water sources such as reclaimed water, surface water from ponds, and well water must be treated, and must be monitored on a schedule that allows verification that pathogenic and toxic contaminants have been removed.  For HACCP to be effective in fruits and vegetables, GAPs must become an integral and validated part of the HACCP program for the producer.  

The final and most crucial aspect of establishing control of water-borne hazards at the farm is the verification plan. There is no safe substitute for a well-designed testing plan to ensure that water of appropriate quality is used to irrigate farmlands. The testing of irrigation water on processing company-owned farms should be an integral part of the quality management plan for the processor; farms not owned by the processor should be contractually obligated to regularly provide certificates of analysis for their irrigation water attesting to the quality of the water. The most basic analyses for water quality (total coliforms, salmonella, nitrates, etc.) should be monitored on a regular basis, while other testing may be done on a less frequent basis unless initial results indicate problems requiring corrective action (Cryptosporidium, Giardia, Shigella, Enteric Viruses, and pesticide residues, to name a few).

Microbac Laboratories, Inc. provides expertise and service in designing a cost-effective water quality monitoring plan to ensure the safety of your fruit and vegetable products.

For more information, please contact: microbac_info@microbac.com.