Twenty-five countries that ship fruits and vegetables to our country violated Canadian pesticide standards last year, according to documents obtained by CTV News.

Documents from the Canadian Food Inspection Agency show that China, France, Thailand, and Nicaragua are among the countries whose exported food is most likely to test positive for certain pesticides.

According to the report, the biggest violator was the Dominican Republic, with 71 per cent of its food testing positive for pesticides, and 16 per cent violating Canadian standards.

The Canadian Food Inspection Agency's Christina Hilliard says the agency conducted some 22,000 tests on imported food last year. While about one in four tests turned up a positive pesticide result, slightly less than one per cent were found to violate standards.

"We found very low violations, certainly under two per cent and those that are found to be in violation…are removed from the Canadian marketplace," she said.

In the case of the Dominican Republic, two Ontario importers were sanctioned and letters were sent to the country's embassy.

According to documents, 10 per cent of food tested from Portugal and Dominica violated standards, followed by Nicaragua (7 per cent), Thailand, France and China (4 per cent).

Hilliard said violation levels are set so that certain chemicals can't appear in quantities that could affect someone's health. She said the CFIA polices these chemicals to protect people's health.

Dr. Murray Isman of UBC's Faculty of Land and Food Services told CTV that Canada has one of the most secure food supply chains in the world.

"I'd hate to have people be dissuaded from eating foods because they're concerned about infinitesimal levels of pesticides," he said.

And Coleen Goto of FreshPoint, which brings food from importers to the retailer, said that the inspection system is very rigourous.

"Even for us to get a case of cauliflower up here, we have probably three pieces of paper that are accompanying that shipment that says it's grown in an area free of certain pesticides, free of certain pests, free of all kinds of things," she said.

Margins in the food industry are typically small enough that a slight delay from an inspector could be disastrous for a business, said Goto. The supplier must also pay to have the produce destroyed, she said.

"You could send them 50,000 different pieces of paper, but if you're going to take $50,000 away from them, that hurts more," she said.

Where does your food come from?

When it comes to knowing where your food comes from, retailers are supposed to put labels on bulk and packaged food.

But several Vancouver grocery stores appeared not to live up to an obligation to label certain produce, according to an investigation by CTV News.

"When the product comes into Canada, it must be labeled," said Christina Hilliard. "It's the retailer's responsibility."

But when CTV News took cameras into Kin's Farm Market in Vancouver, there were several shelves with unlabelled broccoli.

At an IGA, the bok choy was unlabelled. In both of those cases an employee could tell us where the food was from if we asked.

But at a Safeway, when we asked where melons and limes were from, the employee didn't know and couldn't find it in Safeway records. The worker had to call another store before she found out.

Hilliard told CTV News that grocery stores in general do their best to live up to the laws.

But she admitted that more could be done to catch the violations that slip through.

"We don't have provincial inspectors in B.C., but I know that Quebec and Ontario have inspection staff," she said.

For more on CTV's Food for Thought series, click here.