Today, the Food and Drug Administration (FDA) issued a proposed rule to limit N-nitrosonornicotine (NNN), a known carcinogen, in smokeless tobacco products. This is the first time FDA has used its authority to require a standard for tobacco products. Under this authority, the FDA can require changes to tobacco products, such as removal of harmful ingredients, elimination of flavors, or reduction of nicotine levels, in order to protect public health.