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The basics of maximum residue levels in soybeans

Ensuring Canadian soybeans do not exceed the maximum residue level (MRL) for any crop protection product used is critically important, and should be regarded as being everyone’s responsibility. “We’re all doing our part throughout the value chain,” says Dave Buttenham, secretary-manager at the Canadian Soybean Exporters’ Association. “It’s extremely important that we continue to do so, to ensure strong global consumer confidence in Canada’s soybean industry is maintained.”

“We know from our many trips to export countries and hosting many soybean buyer delegations how much our industry’s united approach is appreciated,” adds Jim Gowland, chair of the Canadian Soybean Council and an identity-preservation (IP) soybean farmer near Holyrood, Ontario. “We’re all in this together.”

MRLs relate to levels of any agrochemical used in the production, storage and handling of crops that are allowed in raw and/or processed food products destined for human consumption. MRLs are set by each country’s national government. “In Canada, it’s illegal to sell products containing residues that exceed our MRLs, and similar laws exist in countries that Canada exports to,” explains Buttenham.

Before growers can look at how MRL violations and associated costs can be prevented, it is important to consider first how MRLs are determined. “Because soil type, crop variety and weather conditions can affect plant uptake of crop protection products, MRLs are set high enough to account for this, but low enough to also detect product misuse and protect consumers,” observes Dr. Anna Shulkin, technical registration manager of dietary exposure at Syngenta Crop Protection Canada, in Guelph, Ontario. Different MRLs are established for each crop protection product and commodity combination. MRLs for products that are used in both seed treatments and in foliar applications are usually established based on foliar use. “This is because using seed treatments is not likely to result in any detectable product residue,” Shulkin explains. “Seed treatments are placed on the plant in small amounts at the very beginning of the plant’s life and are therefore usually completely metabolized by the time of harvest.”

MRLs are measured in parts per million (ppm); to illustrate how small these amounts are, Shulkin provides these useful comparisons: “One ppm is like one minute in every two years, or one cent in $10,000.”

Preventing MRL violations
There are several possible reasons why residues exceeding the MRL could be found on domestic and exported grain, keeping in mind that all of them are, of course, preventable. One is the failure to use the recommended label use pattern. “A lot of effort and scientific studies of product safety, efficacy, pesticide resistance, and more, are put into label use patterns, and they should be fully respected,” says Shulkin.

Common examples of off-label use include improper timing of application (a pre-harvest interval outside of specified guidelines in the label range), failure to use recommended label rates and number of applications, and the use of chemicals that may not be licensed in Canada and/or an exporting country.

Violations can also occur because MRLs are not always harmonized between countries. “There have been cases where, even though the grower has followed the label in Canada, the MRL is lower in an export country than it is in Canada, and a violation can occur,” Shulkin explains.

The effort to work towards harmonization of MRLs among countries is ongoing. Buttenham notes that as part of the due diligence in ensuring that safe, high-quality soybeans are delivered to customers, Canadian exporting companies check MRLs and verify that they comply with the rules of the importing countries, as well as pay for third-party MRL testing, and work closely with producers.

Cross-contamination another risk

Another potential risk of MRL violation is the possibility that pesticide-treated seed could be mixed with harvested grain. “Cross-contamination must be completely avoided,” says Shulkin. “We must have a zero-tolerance policy for treated seed entering finished grains for human and animal consumption.”

She notes that just one treated seed can contaminate 50,000 seeds, so only a very small number of treated seeds can be enough to contaminate an entire truckload or storage bin, causing the entire load to be rejected. Enforcement authorities in Canada and in importing countries therefore rely not only on visual inspection, but also on sophisticated analytical methods to detect pesticides at very low levels.

In terms of on-farm practices, those growers who plant treated seed should keep it completely separate from untreated seed and finished grain. “Syngenta advises having strictly designated bins and wagons for treated and finished seed, as well as separate handling areas and bagging lines,” Shulkin says. “This means all handling, transportation and storage equipment should be clearly labelled and effective training should be in place.”

If it is not practical to have completely separate equipment, then it is very important to put cleanliness first. “Visual inspection isn’t enough when dealing with farm equipment and treated seed,” Shulkin stresses. “If equipment is used to handle treated seed, the equipment (storage bins, loading and unloading equipment, transportation vehicles, etc.) should be thoroughly cleaned afterward.”

Gowland observes that soybean growers are diligent in taking the steps needed to ensure cross-contamination is avoided. “The potential risk that treated seeds could be mixed with harvested grain is always on a grower’s mind,” he says. “It is best to be proactive and take all necessary precautions to consistently ensure the highest quality product is delivered to our customers.”

Costs of an incident
For instance, when a violation occurs in soybeans imported to Japan, the amount of testing is increased by 30 percent for every exporter from a given country, notes Shulkin. If a second violation occurs, it increases to 100 percent.

“In a country such as Japan, random testing is done for an extensive list of agrochemicals,” adds Buttenham, “and should they receive a result that exceeds the Japanese MRL for a particular chemical, a specific test for that chemical would be done.”

Should the result of the second test exceed the Japanese tolerance, the importer of the cargo would be asked to ship the product back to the country of origin. Direct costs to return a shipment can exceed $40,000 for a single container, with the potential to run into the millions of dollars for bulk vessel or multi-container shipments. “If it’s a one-time infraction, the immediate costs could include the value of the shipment plus any incremental costs levied by the importing country,” says Buttenham. There are demurrage costs, unloading and re-loading charges, storage charges, domestic transportation charges in the country of import, testing costs, ocean freight charges to return the shipment to Canada, customs clearance to bring the goods back into Canada, and transportation costs to return the shipment to the processor’s plant. The exporter could also be subjected to having every future shipment tested on arrival at the overseas destination. “There is also the related issue of trying to find a home for goods that may exceed Canadian tolerances,” Buttenham observes. “The shipment might have to be destroyed.”

Besides monetary losses, there are also intangible costs of any MRL violation. “While the exporter bears the majority of the cost, the growers also lose in terms of having less diverse markets for their crops, lost food soybean premiums and the lost basis appreciation relating to export,” says Buttenham. “There could also be damage to the reputation of Canadian growers and exporters as suppliers of safe agri-food products.”

Added to that are the possibilities of lost future business, cancelled contracts, banning of future shipments to a particular country and loss of license for the exporter. “Canada currently enjoys a global reputation of being a reliable exporting nation that delivers safe and consistent agri-food products,” says Buttenham. “No one wants that reputation damaged.”

Having said that, if an MRL incident does occur, “As an industry we must conduct a full analysis to find out exactly why it happened and how to prevent it next time,” says Gowland. “The Canadian soybean industry already has quality assurance and traceability programs such as CIPRIS in place, but we are committed to adding to these excellent programs and steadily improving practices to ensure Canadian soybeans stay extremely well regarded and meet the needs of our international buyers.”

For more information
Prevention of Treated Seed Entering the Food or Commercial Grain System is a one-page comprehensive checklist that outlines standard and enhanced protocols that producers can use to ensure they do not contaminate their grain and oilseed shipments with treated seed or its residues. It is produced by the Canadian Seed Trade Association, Ontario Agri Business Association and Grain Farmers of Ontario, and is available at

November 30, 1999  By Treena Hein


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