Uncooked, milled rice is no more harmful to birds than rice in the field, Cheesman said. The Curator of Ornithology at the University of California at Berkeley agrees. It's a myth. Many churchs and reception halls have rules prohibiting the throwing of confetti or rice. These rules work to keep the property clean so that the next happy couple doesn't get its send-off amid the leavings of the previous pair.
Rice poses a unique danger.
Far better to prohibit rice throwing at a wedding than to end up with an injured guest. Don't do it for the birds, do it for the inlaws. In The Simpsons episode of 14 May 2000, Bart is warned not to throw rice at Otto's wedding, lest he cause birds to explode.