The massive international food recall due to possible Listeria contamination of fruits and vegetables shows that it's not just meat processing that should concern consumers.

Nor are pathogens the only hidden menace. Veggie burgers and dogs also do generally worse than their meat equivalents for undeclared allergens and ingredients, missing ingredients, and hygienic issues. And research also shows those veggie products may secretly contain meat.

The big recall that began last month involves frozen fruits and vegetables and processed products from CRF Frozen Foods in Washington state. The company's products include 40 different brands names sold in all 50 states, as well as in Canada and Mexico. The recall continues to grow because other processed foods use CRF ingredients.

The U.S. Centers for Disease Control and Prevention says there have been eight hospitalizations and two deaths.

More L isteria outbreaks

The virulent and sometimes deadly Listeria bacteria have been associated with meat packing in the Canadian psyche, in no small part because of an outbreak in 2008 that killed 22 people and was linked to Maple Leaf Foods in Toronto.

Earlier this year, a Listeria outbreak traced to Dole packaged salads was linked to four deaths, three of them in Canada. (Justin Sullivan/Getty Images)

Earlier this year, Dole Foods closed its plant in Springfield, Ohio, for three months after its packaged salads and other vegetables were linked to four Listeria-related deaths, including three in Canada. Last month, the U.S. Justice Department launched a criminal investigation into the outbreak.

The CDC says the U.S. has about 260 deaths and 1,600 illnesses every year because of Listeria.

Sylvain Charlebois, the new dean of management and a professor of food distribution and policy at Dalhousie University, says most Listeria-related recalls are traced to processing machinery that wasn't cleaned properly.

On May 16, the CFIA announced a recall of Quaker Harvest quinoa granola bars because of Listeria concerns. (Canadian Food Inspection Agency)

"Once it's in the machine it will probably put Listeria on every product that machine processes."

In the past two weeks, the Canadian Food Inspection Agency (CFIA) has recalled Dr. Praeger's black bean veggie burgers, Trader Joe's quinoa veggie burgers and Quaker Harvest quinoa granola bars because of Listeria. All three originate in the U.S. and may contain ingredients sourced from CRF Frozen Foods.

Veggie burgers more problematic than meat burgers

It wasn't just Listeria-related recalls that made May a tough month for veggie burgers.

A California biotech company, Clear Labs, also issued a "Hamburger report" that provides comparative data for veggie burgers. "Veggie burger products are almost twice as problematic as the overall sample set that we tested," Clear Labs co-founder Mahni Ghorashi says.

Compared to the meat-based burgers, he says the veggie versions have the most cases of missing ingredients, including a black bean burger that had no black beans, and higher rates for pathogens and hygienic problems (like rat DNA and human DNA). Two of the veggie burgers (out of 89) contained trace amounts of beef. Another product contained undeclared rye, which is high in gluten.

Clear Labs' testing revealed 14 products were missing listed ingredients such as "apricot, buckwheat, brown rice, barley, corn, jalapeno pepper, bell pepper, onion, tomato, and various spices."

A microbiologist extracts Listeria bacteria for genome sequencing in a CDC lab in Atlanta. (David Goldman/Associated Press)

Meat in veggie dogs

A 2015 Clear Labs report looked at hot dogs, and veggie dogs also fared poorly compared to the meat versions. Ten per cent of the veggie dog brands tested contained undeclared meat.

Ghorashi says the higher rates of problems with the veggie products are "likely due to the fact that there are more inputs involved in the manufacturing of veggie products."

"The procurement and manufacturing process is also far more complex than regular meat products," he adds.

Clear Labs sourced its samples for the reports in northern California, but Ghorashi sees no reason why the results would differ in other parts of the U.S. or in Canada, given the North America-wide supply chain and products.

For Charlebois, these finding are further proof that the "dominant paradigm believing that vegetarian or vegan products or organic products are safer," is not necessarily the case.

Detecting food safety problems

Clear Labs' co-founder Mahni Ghorashi says one reason veggie burgers have more problems than meat burgers is that they have more ingredients. Procurement and manufacturing is also more complex for the veggie products. (Clear Labs)

Ghorashi says the North American food supply chain performs fairly well compared to elsewhere, while Charlebois co-authored a report in 2014 that found Canada's food safety system came out on top when compared to 17 other industrialized countries.

But given the number of CFIA food recalls since his report came out, Charlebois says Canada's performance now warrants further investigation.

During the 2015-2016 fiscal year, Canada had 266 food recall cases — some of which expanded to include multiple product recalls — down from 366 the year before.

The dates are for the fiscal year beginning March 1. Charlebois says consistency in the number of food recalls is a key benchmark for a country's food safety performance.

More recalls could result from greater vigilance and/or poorer products.

Food safety researchers, including Clear Labs and CDC, have a new tool, whole genome sequencing. It was used to investigate the CRF Frozen Foods products, the Dole packaged salads and a Listeria outbreak last year that killed three people and was traced to Blue Bell ice cream.

Ghorashi says genome sequencing should turn up any pathogens present, including ones for which a product is not even being screened under normal procedures, and can also reveal what's not there.

"Technologies haven't been available until now to screen a wide variety of food product categories that may or may not be higher risk," he says.

The cost of genome sequencing is dropping very rapidly, he says, and the technology is headed towards more miniature and portable devices that can be integrated with a smartphone, so consumers could screen products at their supermarket.

"We're five to seven years out from that being a reality," Ghorashi says.

What should consumers do?

"The most important risk manager in the entire food chain will remain the consumer, no matter what," Charlebois says.

Noting that many "foodborne illnesses can be prevented if people actually prepared their foods properly at home," he says consumers need to become more diligent when preparing vegetarian dishes, especially during the hotter summer weather, when the illness numbers usually rise.

Listeria can grow in very cold temperatures but doesn't survive at regular cooking temperatures.

Both Charlebois and Ghorashi suggest taking the same precautions with vegetables as with meat-based products: be discerning about brands, fully cook veggie products and work with clean hands, knives and cutting boards. And if you're eating fresh produce, make sure it's thoroughly washed.