Carcinogenicity
Monomethylhydrazine, as well as its precursors methylformylhydrazine and gyromitrin and raw Gyromitra esculenta, have been shown to be carcinogenic in experimental animals. Although Gyromitra esculenta has not been observed to cause cancer in humans, it is possible there is a carcinogenic risk for people who ingest these types of mushrooms. The toxins may be cumulative and even small amounts may have a carcinogenic effect. At least 11 different hydrazines have been isolated from Gyromitra esculenta, and it is not known if the potential carcinogens can be completely removed by parboiling.
Read more about this topic: Gyromitrin