In mammals nitromethane (1) is probably metabolized to formaldehyde (2) and inorganic nitrite (3). This reaction has so far only been shown in vitro.
Further degradation of formaldehyde (2) see on metabolism page of formaldehyde. Nitrite may be excreted in urine. It may be possible that carcinogenic N-nitroso compounds formed from nitrite and secondary biogenic amines are responsible for the recently found carcinogenic potential of nitromethane (1).