Spirulina was used as a lot by the Aztecs and by Africans who lived by Lake Chad if I remember correctly...and Alfalfa is only potentially dangerous in the form of fresh alfalfa sprouts. I think they are rather safe.

Don't take too much spirulina without supplementing with B-12 though. The B-12 in spirulina is an analog that our body can't use...and if you don't get B-12 from other sources it could possibly cause some problems.