National Toxicology Program

2-Amino-3,4-dimethylimidazo [4,5-f]quinoline (MeIQ)/ (CAS#77094-11-2)
2-Amino-3,8-dimethylimidazo [4,5-f]quinoxaline (MeIQx) / (CAS#77500-04-0)
2-Amino-1-methyl-6- phenylimidazo [4,5-b]pyridine (PhIP) / (CAS#105650-23-5)

• Primary Uses or Exposures: MeIQ, MeIQx, and PhIP are part of a series of heterocyclic amines (HCAs) that are formed in food during heating or cooking at high temperatures and are found in cooked meats and eggs and also in cigarette smoke. The RoC listing of these selected heterocyclic amines is based on findings from oral studies in multiple species of experimental animals that showed cancer in multiple organs including forestomach, cecum, colon, liver, oral cavity, Zymbal gland, mammary gland, and skin. Although evidence from human epidemiology suggests that consumption of well-done or grilled meat (which may contain these and/or other HCAs) may be associated with increased cancer risk in humans, the data are insufficient to support the conclusion that this risk is due specifically to MeIQx, MeIQ or PhIP present in these foods.
• Nominated by: NIEHS (MeIQ/ MeIQx) and private individual (PhiP)
• Basis for Nomination: IARC¹ classification as possibly carcinogenic to humans based on sufficient evidence in experimental animals and recent reviews of the carcinogenicity of heterocyclic amines
• Current Status: Listed in the RoC as reasonably anticipated to be a human carcinogen since the 11th RoC (2004)

¹ International Agency For Research On Cancer (IARC)