Two recent study looked at the microbial load on RPC containers.
Two recent study looked at the microbial load on RPC containers.

Two recent studies of bacteria on reusable plastic containers — both sponsored by corrugated carton groups — question the cleaning process used on RPCs before they enter the supply chain again.

RPC supplier IFCO and the Reusable Packaging Association has countered that no foodborne illness outbreak has been traced to RPCS.

Keith Warriner, professor of food safety at the University of Guelph in Ontario, Canada, said the study of RPCs — commissioned by the Canadian Corrugated and Containerboard Association — was an extension of one he performed in 2013. The first study tested 50 RPCs, while the 2014 study involved 160 RPCs.

In the 2014 study, RPC samples from five Canadian packing facilities were pulled from different lots of trays that had been delivered on pallets wrapped with plastic film. Corrugated cartons from those facilities were not tested for comparison, Warriner said.

The study found that 13% of the RPCs tested positive for generic E. coli, but none tested positive for salmonella; 73% exceeded bacterial load levels, although that doesn’t mean they tested positive for E. coli, salmonella, listeria or other pathogens commonly associated with foodborne illness outbreaks.

“The results of the study have confirmed that a high proportion of RPCs are of poor sanitary status due to inadequate sanitation or post-cleaning contamination,” Warriner said in the study’s conclusion.

Trevor Suslow, produce safety specialist and plant pathologist at University of California-Davis, also conducted a recent study of RPCs, “Assessment of General RPC Cleanliness As Delivered for Use in Packing and Distribution of Fresh Produce.” Corrugated Delivers sponsored efforts to publicize the results and International Paper sponsored the testing.

Suslow said his research shows inconsistencies in the system for handling pooled RPCs. The difference between the Canadian study and Suslow’s is that his research tested RPCs with visible organic matter or residual produce material.

“The main takeaway from that is that we found, other than in a few cases across a few different weeks or pallet loads, the units that looked visually clean and dry had very similar viable or living microbial indicator counts compared to the ones we pulled apart for cause,” he said.

A general inconsistency in cleaning and sanitation of pool RPCs was observed in his findings, he said.

“There are improvements that need to happen, in my opinion,” he said.

That could include periodic inspections of RPCs and spot cleanliness testing. That could provide valuable feedback to buyers and RPC providers, he said.

“One of my main points throughout this process is trying to utilize the information for what it represents and not get into trying to undermine the different types of materials that have various benefits, because if you do anything to erode consumer confidence in consuming fresh produce no one is going to win,” he said. “We do these studies so we can progressively and systematically highlight areas for improvement, and clearly this is one of them.”

Dan Walsh, president of IFCO North America, Tampa, Fla., said in an e-mail that there has never been a verified incident of foodborne illness directly or indirectly related to IFCO RPCs.

“Our grower customers and retailer partners trust us to provide them with sanitized containers each and every time, and that’s exactly what we deliver," he said. “We will continue to work collaboratively with others in the packaging industry and with growers and retailers to ensure that the food supply chain remains safe and secure.”

According to a prepared IFCO statement in response to the Canadian study, more than 1 billion cases were shipped via RPCs in 2013, and third-party tests between March and August showed significantly lower microbials active on RPCs than cardboard boxes immediately prior to packing.

All IFCO RPCs sent to service centers are properly washed and sanitized, according to the statement, and IFCO conducts internal and external sanitation audits to validate the cleanliness of RPCs.

No cardboard, RPC or other transport packaging have been found to be the cause of any food safety incident, according to the company.

“IFCO does not believe in using an issue as serious as food safety to gain a competitive edge, rather we commission microbial tests only to inform our ongoing efforts to improve food safety across the fresh produce supply chain — not just in our own operations but in those of our customers and partners,” according to the statement.