How to dispose of rhododendron prunings?

I have some huge rhododendron and laurel hedges which I'm going to cut down drastically. This will leave an enormous heap of trash. Someone told me you shouldn't burn it as it gives off cyanide, or arsenic, I forget which, so shredding and composting is probably out too. Is this correct? Shall I have to get the council to collect it, at great expense?