The U.S. Food and Drug Administration this week released an environmental assessment inspection report on how exactly the cantaloupes linked to a deadly 2012 Salmonella outbreak may have been contaminated. The report comes six months after Chamberlain Farms in Owensville, Indiana was pinpointed as the source of the outbreak, which sickened 261, including three deaths, in 24 states. According to the report, the initial contamination of the cantaloupes “likely occurred in the production fields and was most likely spread by operations and practices in the packinghouse. It is also likely that the contamination proliferated during storage and transport to market.” During an inspection of the Chamberlain Farms packinghouse from August 14  t0 31 of last year, FDA found a number of conditions that could have contributed to the spread of contamination. According to the report, the food contact and non-food contact surfaces in the packhouse were constructed with materials that couldn’t be easily cleaned or sanitized, including carpet and wood. The FDA also said that records were not available to demonstrate whether the farm had monitored its water for washing the melons had the proper pH for disinfecting and preventing cross-contamination. The report also notes there was an accumulation of debris including trash, wood, food pieces, standing water, mud, and dirt observed beneath the conveyer belt in the cantaloupe packinghouse and that the melons were not pre-cooled after packing before shipment to retail stores. “Warm cantaloupe with rinds that have an increased water-activity (i.e., free residual moisture from washing procedures) and available nutrients from contact with insanitary food contact surfaces may have facilitated Salmonella survival and growth on the cantaloupe rind during subsequent holding,” according to FDA. FDA also offered detailed hypotheses on the different ways the cantaloupes could have originally become contaminated in the field, from the report:

  • Biological soil amendments may have been the source of the pathogen; however, Chamberlain Farms reported that the firm does not use any biological soil amendments for the production of cantaloupes or watermelons.  It is unclear if adjacent or previous land use may have played a role in this. It was noted by the EA team that significant poultry (turkey) production is located in the local region of Chamberlain Farms.
  • Additionally, it was hypothesized that agricultural water may have been a vehicle for the spread of contamination. Chamberlain Farms did report that subsurface drip irrigation was used on three of the four fields visited during the EA. However, Chamberlain Farms reported that they did not use any irrigation water for the production of cantaloupe or watermelons on Parcel A (a parcel where, both watermelon (collected by Indiana State Department of Health) and soil samples (collected by FDA) were found to be positive for Salmonella).   This is extraordinary given the water use demands typically required to commercially produce cantaloupe and watermelon, particularly given the extreme heat and drought conditions which occurred in Southwest Indiana during the summer growing season of 2012.
  • Although none of the wells tested positive for Salmonella, it is interesting to note the positive findings of generic E. coli and total coliform. While the E. coli and total coliform are not pathogenic, nor are they necessary indicators of the presence of Salmonella, it is unusual to note indicators of fecal contamination to be recovered from ground water sources.  It was reported to FDA that the local aquifer is very shallow (30-40ft) and subsequently all wells are dug only to this depth.  This is of interest for the following reasons:  The combined information listed above supports the hypothesis that agricultural water may have been a contributing factor.
    • Due to the location of the Large Well to Scott Ditch (dug to 15ft), which did test positive for Salmonella, E. coli, and total coliform, it is possible that Scott Ditch is influencing the aquifer at the location of the Large Well.
    • The observations from the EA team that some of the wells were poorly constructed, or were in disrepair, suggests they may have been subject to contamination by run-off, or through subsurface influences.

The FDA reminded growers that all parties along the produce supply chain should employ best practices to ensure safe food. The federal government has recommendations for growers in FDA’s and USDA’s “Guidance for Industry: Guide to Minimize Microbial Food Safety Hazards for Fresh Fruits and Vegetables,” FDA’s “Guidance for Industry: Letter to Firms that Grow, Harvest, Sort, Pack, Process, or Ship Fresh Cantaloupe,” and FDA’s “Guidance for Industry: Guide to Minimize Microbial Food Safety Hazards of Melons; Draft Guidance.”