Is that chalk in your garlic powder?

One of the world's foremost experts on food fraud is warning about the possibility that garlic powder on store shelves including those in Canada may contain inferior ingredients.

Prof. Christopher Elliott, director of the Institute for Global Food Security at Queen's University Belfast in Northern Ireland, is sounding a note of caution after noticing two trends he says don't add up.

Garlic sales around the world so far this year are on pace with those last year, Elliott said, despite a particularly cold bout of weather that laid waste to vast tracts of garlic crops in China, which produces most of the world's supply.

``Where's all the garlic coming from?'' Elliott said in an interview.

Elliott and other researchers are investigating garlic supply chains to determine whether garlic powder has been diluted with other products, such as talcum or chalk.

His suspicions about spices have been right before.

Last year, Elliott published a study that showed about a quarter of oregano sold in the U.K. and Ireland contained other products, including olive and myrtle leaves.

``It didn't matter the price of the oregano _ the very expensive oregano or the very cheap _ the adulteration happened across the full spectrum,'' he said in a keynote speech earlier this week at a global conference in Quebec City about food fraud.

There are common threads Elliott said he looks for when trying to uncover cases of food fraud.

``Has there been crop failures? Are there price wars going on in a particular commodity?'' he said. ``Currency fluctuations are another driving factor (and) political instability and corruption.''

He points to the recent furor over Brazil's meat exports as one example. Several countries halted imports of Brazilian meat last month while investigators look into allegations that health inspectors allowed expired meat to be sold and covered it up in exchange for bribes.

Beyond the fact that customers may not be getting what they're paying for, Elliott said there are safety concerns with food fraud.

Hidden ingredients that are toxic can accumulate and harm one's immune system. People with peanut allergies who are exposed to a product diluted with a peanut ingredient may risk death.

Another concern is the use of pesticides that some countries have banned, which have been found in some adulterated food, Elliott says.

Canada has a robust system to detect pesticides and other chemicals in order to make sure that they fall within acceptable limits established by Health Canada, said Aline Dimitri, the deputy chief food safety officer for the Canadian Food Inspection Agency.

``We haven't really seen any major deviations in the system that would make us worry,'' she said.

Dimitri said the monitoring system randomly checks a wide range of foods for chemical residues, though it doesn't capture the entire food market.

``This is our first line of defence to see if overall the food system is within the tolerance levels that are set for health and safety purposes.''