Aflatoxin is a potent carcinogen. The fungus, genus Aspergillus, that secretes aflatoxin enters the plant usually through the wounds left by an insect pest, since most plants have a hard outer layer that acts as a barrier to fungi. Once inside the plant, the fungus can reach all parts of the plant, including its seeds. Aflatoxin is a serious cause of illness and death in developing countries which have fewer food safety regulations. Some plant scientists are trying to develop transgenic corn with a gene for an enzyme which breaks down aflatoxin. Aflatoxin is listed as a possible carcinogen, and has been shown to cause liver damage, some of which may be cumulative,