no they are not, infact a lot of healthy eating diets recommend snacking on these in between meals. They are very good for you also and are full of zinc, which helps with nail and hair growth, sexual appetite, energy etc etc.
as stylinsam said, they have to be eaten in moderation else they are not quickly eliminated from the system...my aunt has just had an operation cancelled owing to build-up of seeds in the bowel (different types of seed). A small amount is fine though. Some kinds of vitamin pill or capsule can cause the same problem.