I was told there was a family cooking hot dogs and used sticks from the cattail plant and were poisoned. I have not researched this.. thought I would find out from you.@haphazard-hstead you had a slight mention of cattail pollen.. in Texas we are taught those are poisonous. They grow near the beach at the Gulf of Mexico, not far from where I grew up.
I have never heard of cattails being poisonous. I have eaten a lot of cattails and a lot of parts of cattails (Typha latifolia and T. angustifolia) -- the roots, the core of the emerging leaves, the based of young leaves, the young flower spike, and the pollen. The roots are the most trouble to use. And they can take up chemicals in the water, like pesticides or metals - and that's not good for eating at all. So maybe that's why people were cautious of them in your area.