Although raw button mushrooms ( _Agaricus bisporus_ ) do contain a carcinogenic hydrazine, agaritine, a recent review by Roupas et al (2010) concludes:
> The available evidence to date suggests that agaritine from consumption of cultivated A. bisporus mushrooms poses no known toxicological risk to healthy humans.
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Peter Roupas, Jennifer Keogh, Manny Noakes, Christine Margetts, Pennie Taylor, Mushrooms and agaritine: A mini-review, Journal of Functional Foods, Volume 2, Issue 2, April 2010, Pages 91-98