Googling seems to find a lot of stories, including the case of a woman who has been doing it for 40 years (the article claimed 4 pounds daily). Seems pretty credible.
Digestive system obstructions seem to be an (obvious) risk of this type of behavior (that and things like heavy metal poisoning, ugh). Digestive systems are pretty damn robust though, obstruction doesn't seem like an inevitable outcome even with (what seems like) copious ingestion of sand.