Unpublished research may show that S. canadensis (American elderberry) has lower cyanide levels than apple juice, and that its fruit does not contain enough beta-glucosidase (which convert glucosides into cyanide) to create cyanide within that biochemical pathway.
For comparisons, assuming S. nigra has levels of no more than 25 micrograms of cyanogenic glycosides/milligram of berry weight, assuming all of the glycosides were converted to cyanide, and assuming a toxicity of 50 mg for a 50 kg vertebrate, one would need to eat 2 kilograms (~4.4 pounds) of berries in one sitting to reach the lower limits of lethal toxicity (1 mg cyanide/kg of weight).