Hey weird, correct me if I'm wrong, but isn't putting powdered glass in someone's drink a very stealthy way to make them very dead?
Depends on the amount, size, and character of said glass.
Gastric mucosa is surprisingly resistant to puncture. See for instance, people who eat pica.
wikipedia articlePeople with this disorder have been known to eat broken glass, plastic bits, nails, screws, washers, metal jacks (from the children's game), rubber, clay, chalk, wood, pretty much anything that can be eaten (physically) has been reported in the history of the disorder as having BEEN eaten at some point.
Normally, flat glass is not terribly dangerous, as the damaged tissue can dislodge the foriegn debris and seal with normal blood coagulation. The reason feeding crushed lightbulbs to people and animals is due to the curved nature of the glass shards, which undercut into the flesh, then mechanically bind up, and can't be expelled, so the would doesn't heal. This causes increased locallized inflamation, cytotoxic shock, and death.
If you want to kill someone steathfully, adding powdered ricin in their food is better than glass considerably, as it takes time for someone to die from ricin exposure. It works by gumming up the works, essentially. It inhibits normal protein synthesis, leading to multiple organ system failure from metabolic collapse. I understand the process is viciously unpleasant. Itself being an isolated protein from the castor bean plant, the redined poison is a weakly soluble offwhite powder, which is easy to administer, having very little if any flavor or odor.
If you insist on nasty stabbiness in the innards though, fine particles of abspestos sprinked into food and drink over several days or weeks will do it, sooner or later. Abspestos forms microscopic needles with a somewhat serrated surface aspect. The fibers puncture flesh, are/can be like nanoscopic syrenge needles, and are small enough to puncture cell walls, swirl around cellular neuclei, and permit cellular cytoplasm to leak out of cells, killing them. It will cause necrotic lesions and precancerous neoplasms to grow inside the gastric system with persistent administration. The fibers can become permanently lodged in the tissues, causing spreading, horrible pathogenesis.