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On October 26, 2015, the International Agency for Research on Cancer (IARC), a division of the World Health Organization (WHO), announced a monograph declaring processed meats, such as bacon, sausage, and hot dogs, as a Group 1 (carcinogenic to humans) carcinogen, and red meat as a Group 2A (probably carcinogenic to humans) carcinogen. The committee based their classification on an evaluation of over 800 epidemiological studies that investigated the association of cancer with red meat or processed meat consumption in multiple countries.

IARC’s classification “indicates the weight of the evidence as to whether an agent is capable of causing cancer" (technically called “hazard”), but it does not measure the likelihood that cancer will occur (technically called “risk”) as a result of exposure to the agent.” Therefore, although IARC places processed meats in the same group as smoking, it does not mean they increase cancer risk equally. For perspective, IARC explained that processed meats contribute to about 34,000 cancer deaths worldwide, whereas 1 million cancer deaths due to tobacco smoking occur per year globally. Based on an analysis of data from 10 studies, IARC estimated that eating 50 grams of processed meat (this corresponds to approximately 1.8 oz or the equivalent of one hot dog) daily increases the risk of colorectal cancer by 18%. Notably, as suggested in a recent Q&A posted by NPR, the risk of colorectal cancer is already relatively low and dieticians have long recommended eating less red meat and processed foods.

Potential Regulatory Implications

California’s Proposition 65 maintains a list of chemicals known to cause cancer and requires a warning of exposure to listed chemicals to consumers. Earlier this year, OEHHA changed its Prop 65 regulations without voter’s authorization to list substances, as well as chemicals, known to cause cancer, including those classified by IARC as Group 1 and Group 2A. Thus, in response to IARC’s classification of processed and red meats, OEHHA may give notice to add processed and red meats to the Prop 65 list, requiring warnings on packaging for these products. More information on the potential regulatory implications this IARC classification may have on Prop 65 can be found here.