Food safety experts warn hydroponic lettuce not immune from E. coli

Hydroponic lettuce pitched as safer option A Winnipeg man who grows lettuce using hydroponics says the growing method could prevent e-coli outbreaks.

As public health experts in Canada and the United States scramble to determine the source of an E. coli outbreak linked to romaine lettuce, one Manitoba farmer claims the lettuce he grows hydroponically is a safer alternative.

Denny Black, a farmer, grows more than 20,000 heads of Greenleaf and butterhead lettuce at his Neva Farms in Landmark, Man., using this method.

Instead of using soil and manure, Black uses a mix of nutrients including calcium and nitrogen combined with water to grow his crops. The plants, which take about eight weeks to mature from tiny seeds into full grown greens, are grown under artificial lights.

“I think people are looking for an alternative to field grown crops,” Black said.

His method, he claims, could mitigate some risk, since produce can be contaminated with E. coli through the soil, water, animals or improperly composted manure.

But food safety experts warn that hydroponic foods are not immune from E. coli, salmonella or listeria.

"If the seeds for that lettuce are contaminated with a food borne pathogen, you can't, you won't get rid of it even in a hydroponic production system," said Claudia Narvaez, an associate professor in the food science department at the University of Manitoba.

She added that Black’s controlled environment is only moderately safer compared to soil, depending on the source of the water and whether people follow proper safety procedures when handling the produce.

On Friday, the Public Health Agency of Canada said 22 people have tested positive for E. coli in Ontario, Quebec and New Brunswick after eating contaminated romaine lettuce.

It stopped short of issuing a country-wide ban on the vegetable and said it would be dealing with the outbreak on a case-by-case basis. Officials expected more cases would come to light as more people were tested by doctors.

The U.S. Food and Drug Administration said the E. coli strain responsible for the outbreak likely originated in California.

Most E. coli bacteria are benign, but some can cause severe illness, the Public Health Agency of Canada said.

With a report from CTV Winnipeg’s Beth Macdonell