A Guelph food scientist has sparked a debate on plastic versus cardboard in boxes used to deliver produce from farms to grocery stores. Keith Warriner, a University of Guelph professor, released a study late last month that raises concerns about the hygiene of boxes made out of plastic.

In his study released last month, Dr. Warriner again found cause for concern. Using a pass or fail measure, he found a majority of samples (between 83 per cent and 100 per cent of 144 units tested) failed based on total aerobic count, which indicates the presence of bacteria. In 4 per cent of the random samples taken, tests showed the presence of E. coli.

“What we’ve found is those issues we identified back in 2013 still exist,” Dr. Warriner said in an interview. He noted some improvements from the 2014 results, but overall, he said, “the method they have for sanitizing the crates is ineffective.”

In response to the study a spokesperson for IFCO– one of the world’s biggest manufacturers and managers of the reusable crates, slammed the Guelph study as “flawed,” and relying on “faulty methodology.” The spokesperson pointed to more than $125-million IFCO has spent in the past five years improving its sanitation procedures, and added that the company’s crates have never led to any incidents of food-borne illness and listed their own studies which showed plastic boxes as more environmentally friendly.