Uranium, Plutonium, Neptunium, and other actinides are present in the soil and plants around us from above-ground testing of nuclear weapons long ago. With half-lives of millions of years, they will always be there. Unfortunate fact of life.
Based on a population study of 100,000 people there MAY be 2 to 4 additional fatalities from each isotope due to cancer from these various contaminations. With statistics showing that in the same lifetime period, almost 1 in 4 (25,000!) people will develope another type of cancer (lung, breast, bone, etc.) I wouldn't worry too much about eating your oryx.
You would be better off to worry about tornadoes, hurricanes, blizzards, lightning, heart disease, or drunk drivers on the way to WSMR.