A recent study by the University of Guelph deemed sanitation processes for reusable plastic containers unsatisfactory on multiple accounts.

The study did not find a food safety hazard, but researchers argue the study shows a fault in decontamination methods.

The study was contracted by Smithcom Communications Agency, on behalf of the Canadian Corrugated Containerboard Association, in response to complaints by Canadian grower-shippers, who are required to use the containers instead of cardboard boxes to transport their produce.

Many growers were upset by sanitation issues and the costs to rent the containers.

RPCs travel through a cycle in which they are rented, packed with produce, shipped, and then returned to the U.S. for cleaning. The circulation of the containers throughout the industry means pathogens also can circulate.

Despite complaints, reusable packaging offers attractive financial and environmental benefits.

“RPCs offer lower costs through greater handling efficiencies, improved product protection, resulting in shrink reduction and higher product quality, and lower environmental impact,” said Jerry Welcome, president of the Reusable Packaging Association.


The study was conducted by Keith Warriner, the director of the food safety and quality program at the university’s Department of Food Science.

It assessed the RPCs on five levels: visual inspection, ATP readings, total aerobic counts, enterobacteriaceae, and E. coli/coliform counts.

Because there are no food safety standards in place for the Reusable Packaging Association, Warriner used his experience in the meat industry to establish sanitation standards for the study.

The standard was set at what the researcher expected of a clean “low-risk contact surface.”

Researchers visited five Canadian packing facilities in Hamilton, Leamington and Montreal. They selected 10 random RPCs from each location.

Warriner immediately ruled out contamination on the grower level because the containers were sampled as they were delivered.

Warriner first became suspicious during visual inspection of the containers when he noticed labels from previous growers were still stuck to the plastic, indicating they had not been properly sanitized.

He also noticed physical damage on some of the RPCs, which could allow “niches for contamination to accumulate and become inaccessible to sanitizing agents,” according to the study.

“It was evident from visual inspection and analysis that a proportion of the RPC had neglected to be cleaned or decontaminated effectively,” according to the study.

The sampled RPCs had varying levels of sanitation. Overall, 64% of all RPCs failed the researcher’s set sanitary standards in total aerobic counts. All of the containers passed in the E. coli/coliform counts.

Warriner suspects two situations are at the root of contamination.

First, the RPCs are sent back to the poolers without further cleaning. Second, the containers are being washed but not sanitized.

“There’s a difference between cleaning and sanitizing,” he said.

In conclusion, Warriner suggests that though no pathogens were detected, the RPC decontamination method should be revised.

“There’s nothing wrong with plastic trays,” Warriner acknowledged. “The fact is, there are systems that can successfully clean these trays.”

No pathogens, no change

According to Welcome, cleaning is an integral step in the circulation of the containers.

He argues there is no need to monitor safety standards within the Reusable Packaging Association because each pooler has to meet the standards of Manhattan, Kan.-based AIB International.

“If the member companies felt it would be advantageous for RPA to help establish an industry-recognized safety standard we would do it, but the AIB is recognized as one of the food industry’s leading food safety organizations, and their standards and guidelines are generally recognized as acceptable safety standards,” he said.