Tomalley is the hepatopancreas (the organ that fulfills the functions of both the liver and the pancreas) of a lobster, crab or other arthropods of a crustacean when used for culinary purposes.

It can, however, contain high levels of polychlorinated biphenyl (PCBs), dioxins, PFOA and mercury which can give rise to a number of negative health effects.

In July 2008, a report from the Maine Department of Marine Resources indicated the presence of high levels of paralytic shellfish poisoning toxin in some tomalley from lobsters in that state.

[5] Also in July 2008, Massachusetts Department of Public Health reminded consumers not to eat American lobster tomalley, because it can build up high levels of toxins and other pollutants.

[5] As of 2009 Maine has had a consumption advisory on lobster tomalley tissue for women who are or may become pregnant and children, because of mercury, PCBs and dioxins accumulating in it.