Canadian Grain Commission says the low cadmium durum breeding program launched in the early 1990s has paid off
Cadmium concentrations in Canada’s durum wheat exports have decreased significantly over the past three decades, thanks to the adoption of new low-cadmium durum varieties, says a new research paper co-authored by a scientist at the Canadian Grain Commission.
Cadmium is a naturally occurring heavy metal that exists in Western Canadian soils. It can have a negative impact on human health if consumed in large enough quantities.
In the early 1990s, a durum breeding initiative was established in Canada, aimed at developing new varieties of low-cadmium durum that were less conducive to cadmium uptake.
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Samples of durum collected at export position and analyzed for cadmium content over the past 30 years suggest that the development and adoption of low-cadmium varieties has had a significant positive impact on the quality and safety of Canadian durum being shipped abroad, according to the CGC paper.
“It’s a good news story,” said Sheryl Tittlemier, a research scientist at the CGC’s Grain Research Laboratory in Winnipeg and co-author of the report.
“We saw a very significant decrease in cadmium concentration in exported durum. And as you probably know, the bulk of durum grown in Canada is exported so it’s very important to meet customers’ regulations (for maximum acceptable levels of cadmium) ….”
The paper’s findings are a tribute to Canada’s durum value chain, from plant breeders who developed low cadmium varieties, to producers who adopted them and organizations involved in the variety registration process, Tittlemier added.
In the early 1990s, some overseas buyers of Canadian durum were concerned that cadmium concentrations in Canada’s export shipments were exceeding customer specifications or internationally recognized maximum cadmium levels.
Durum breeding efforts aimed at reducing cadmium levels in incorporated genetic material from low cadmium accumulating parent lines.
By late 1991, all new durum cultivars under development in Canada were required to have at least at least one low cadmium parent line.
By 2004, low cadmium accumulation was formally adopted as a requirement for the registration of all new durum cultivars registered in Canada.
In 2001, Napoleon became the first low cadmium durum cultivar registered for commercial production in Canada.
Cadmium concentrations in bulk durum exports are routinely monitored as part of the CGC’s cargo monitoring program.
Samples collected and analyzed between 1992 and 2020 show a significant reduction in mean and median cadmium values.
A similar assessment of cadmium values in export shipments of Canada Western red spring (CWRS) wheat between 1994 and 2019 shows that cadmium accumulations in CWRS wheat remained relatively stable.
This supports the conclusion that efforts focused on reducing cadmium in durum were exclusive to durum and were not the result of other factors, such as environmental changes.
According to Tittlemier, there are three primary determinants of cadmium in harvested grains — crop species, variety selection and soil characteristics.
Data presented in the paper suggest that a significant and consistent reduction in cadmium levels of exported durum began to emerge between 2005 and 2007 when low cadmium accumulating varieties such as Strongfield started to gain widespread adoption among commercial grain growers in the West.
The subsequent registration and widespread cultivation of other low cadmium varieties such as Transcend, Verona, Brigade and Spitfire helped to ensure that Canada’s export shipments consistently meet the specifications and regulatory requirements of buyers around the world.
Between 1998 and 2005, four high cadmium accumulating durum varieties — Kyle, Navigator, Morse and Avonlea — comprised 78 to 95 percent of all the durum produced in Canada.
But by 2019, the same four varieties accounted for only two percent of the durum grown in Canada.
“The decrease in cadmium concentrations on CWAD bulk exports is consistent with the decrease in planting of high cadmium accumulating cultivars in the mid-2000s …,” the paper states.
“The decrease in cadmium concentrations continues through the late 2000s and early 2010s, with concentrations appearing to plateau in the late 2010s,” it adds.
Since 2010, when most durum grown in Canada was planted with low cadmium accumulating cultivars, all CWAD bulk exports have complied with the Codex maximum cadmium level of 0.2 milligrams per kilogram in wheat.
A full version of the research paper can be found at bit.ly/3h9FYo0 or at www.tandfonline.com/doi/full/10.1080/19440049.2022.2130441.
