Getting Cadmium Out of Sunflower
Sunflowers in Fargo North Dakota..
The annual $25 to $30 million U.S. sunflower kernel market in Germany might
have become a thing of the past, were it not for the efforts of the
Agricultural Research Service.
The agency presented evidence that convinced German authorities to set a
reasonable guideline for cadmium levels in kernels.
The Germans had been considering a 0.3 parts per million (ppm) maximum
allowance for kernels destined for human consumptiona standard that would
have been impossible to meet with current sunflower varieties. Instead, in
1992, the Germans, set the level at 0.6 ppm, which U.S. farmers can reliably
meet by avoiding a handful of high-clay soils in the Red River Valley.
But eventually it won't matter which soils sunflowers are grown on. As a
long-term solution, ARS scientists are breeding hybrids that will take up less
cadmium. The breeding effort is the focus of a cooperative federal, state, and
industry project led by Rufus L. Chancy, an agronomist in the ARS Environmental
Chemistry Laboratory in Beltsville, Maryland.
Chaney has worked with Jerry F. Miller, an ARS geneticist in Fargo, North
Dakota, who is the plant-breeding cooperator on the project. Miller and
colleagues selected the 200 strains that were tested to breed the new hybrids.
Cadmium is a trace metal that occurs naturally in all soils, although the
levels are somewhat higher in soils in the Northern Plains sunflower country.
Chancy says the revised German guideline is not based on health risk but on
typical cadmium concentrations found in crops grown on uncontaminated soils.
So he joined with other USDA colleagues and the National Sunflower
Association in Bismarck, North Dakota, and with Albert A. Schneiter of North
Dakota State University's Department of Crop and Weed Sciences at Fargo.
Chancy found that only high-clay soilssuch as Fargo silty
clayand those containing high chloride levels produce seeds with cadmium
levels above the guideline. Because of this finding, some sunflower companies
have reduced the number of contracts with farmers for kernels grown on these
In studying 200 sunflower genotypes in North Dakota and Minnesota, Chaney,
Schneiter, Miller, and postdoctoral associate Yin-Ming Li found some that have
genes for lower cadmium uptake.
"We tested these plants in fields in North Dakota to find the best
ones," Chaney says. "The industry is already using the low-cadmium
genes we have identified to breed new sunflower hybrids."
Two seed companies are doing the breeding work and one expects to have
lower-cadmium hybrid seed for sale in 1996 or 1997. By Don Comis.
Chaney is at the USDA-ARS Animal Manure & By-Products Laboratory,
Building 306, 10300 Baltimore Ave., Beltsville, MD 20705- 2350; phone (301)
504-9100, fax (301) 504-8162
Miller, is at the USDA-ARS Northern Crop Science Laboratory, P.O. Box 5677,
University Station, Fargo, ND 58105- 5677; phone (701) 239-1321, fax (701)
"Getting Cadmium Out of Sunflower
Seeds" was published in the
January 1995 issue
of Agricultural Research magazine.