Study: results mixed on organic produce

The University study is the first comparing organic and non-organic practices at the farm level.

Hayley Odom

Organic produce might contain more contamination than conventional produce does, according to a recent study by University researchers.

The study – concerning the potential for disease-causing bacteria and fecal contamination in organic and non-organic produce that has not yet been harvested – is the first study comparing organic and non-organic practices at the farm level.

The results revealed a low potential for disease-causing bacterial contamination in organic produce, but found a higher risk of fecal contamination in organic produce – compared with non-organic produce – because manure usage is a primary source of fertilization in organic farming.

But the findings stated organic produce grown at certified organic farms did not contain higher levels of fecal contamination.

“These are mixed results,” University professor Francisco Diez-Gonzalez, senior co-author of the study, said. “The study doesn’t say organic produce is completely safe, but there’s nothing to be paranoid about in terms of safety of organic vegetables.”

But the mixed interpretation of the results sparked some apprehension about the risks of organic produce.

“It’s a shocking, galling interpretation,” said Alex Avery, research director for the Center for Global Food Issues.

“If there’s more fecal contamination, there’s more of a likelihood of pathogenic strains of E. coli or pathogenic bacteria,” he said.

Researchers conducted the study on produce that had not yet been harvested to determine how farming techniques affect organic produce.

“Bacteria contamination can happen once the product is harvested and that doesn’t necessarily reflect the impact of the organic practices,” Diez-Gonzales said.

The research samples came from organic and non-organic farms in central and southern Minnesota. The produce samples included tomatoes, leafy greens, lettuce, broccoli, strawberries, apples and several other types of produce, according to the study.

Diez-Gonzalez said the difference in contamination levels between produce from certified and uncertified farms was one of the study’s major findings.

“This is very relevant because it means that some of the practices that certified farmers used reduces the prevalence of E. coli,” he said.

Certified organic farmers have stricter controls, including using composted manure – a process that kills disease-causing bacteria – and represents little risk of fecal contamination, he said.

He also said the results do not reflect the produce bought at the retail level.

Barth Anderson, organic certification coordinator of the Wedge Community Co-op in Minneapolis, said organic food is not problematic on an outbreak level.

“We’ve never had a contamination complaint from a customer regarding organic or conventional produce,” he said.

He said 99 percent of the organic produce the store sells is from certified organic farms.

Agriculture education junior MaryAnne Bedtke, who buys organic produce, said the study’s results do not worry her because conventional farming practices also use manure as fertilizer.

Horticulture science professor Cindy Tong said the results are not problematic because Americans in general do not eat enough fruits and vegetables on a daily basis.

“Food-borne illnesses due to fruits and vegetables are a small percentage of all outbreaks,” Tong said.