@switchable - yes, children have swallowed the large beads ('Water Balz'), and it has lead to obstructions of the small intestine. However, perhaps one should emphasize the words 'children', 'swallowed', 'the large beads', and 'small intestine'. The ball expanded to 1.5" in the case of the toddler (see CU link), which is a big risk in the small intestine of a child, but pretty moderate for a grownup toy. Basically, I'm arguing that there are miles of difference between these known hazards, and any grownup activity
http://well.blogs.nytimes.com/2012/09/17/expanding-ball-toy-poses-hazard-to-children-and-pets/
http://www.consumerreports.org/cro/magazine/2013/05/polymer-balls-raise-alarm/index.htm
I know I must sound like a broken gramophone, but I guess I feel the comments I've been getting represent, well, a 'non quantitative' risk assessment.
Also the second use of the beads (gardening, flower arranging) is independent of their toy use. I don't think that www.magicwaterbeads.com is the same company as Water Balz. They are basically a commodity item.