Lots of plants produce toxins to ward off herbivores, and horseradish is no exception. However, humans are masochists and are weirdly into that which led to use of all sorts of mildly toxic stuff to flavor our food. But, we're also not the only animals that ingest toxic substances.

ex: koala, vultures

http://www.bbc.com/earth/story/20160721-there-are-animals-that-eat-soil-toxins-and-even-their-poo


haggadah Section: Maror