Sales of bacon and sausages fell by £3m in UK supermarkets in just two weeks following the World Health Organization’s announcement that processed meats are “definite” carcinogens.
The International Agency for Research on Cancer (IARC), the specialized cancer agency of the World Health Organization, placed processed meats in the same category as smoking, asbestos and plutonium. But, shocking as that sounds, it does not mean that the risk of cancer is elevated to the same level by all these substances or processes.
Justin Davies, Consultant Colorectal Surgeon at Addenbrooke’s Hospital, Cambridge and Clinical Adviser at Check4Cancer, explains: “Knowledge is one of the keys to fighting or avoiding cancer; if we know what to avoid, we have the potential to reduce our risk. This list can help us towards that goal, but it needs to be understood in context. While all the substances in the Group 1 category have been shown to be carcinogens, they are not necessarily equal in terms of their potency, or the risks they pose. To understand the level of risk, we need to consider each item individually. There is no safe level for smoking, for example, which tops the list as the world’s number one carcinogen. But – as with alcohol, which is also on the list – the increase in cancer risk from consumption of processed meat is directly related to intake. Moderate and infrequent consumption of processed meats such as bacon and sausages represents a very small increase in risk – although for those already at elevated risk of colorectal cancer, cutting these out completely may well be the desirable option.”
Experts concluded that each 50g portion of processed meat eaten daily increases the risk of colorectal cancer by 18%. Processed meat refers to meat that has been transformed through salting, curing, fermentation, smoking or other processes to enhance flavour or improve preservation. Examples of processed meat include hot dogs (frankfurters), ham, sausages, bacon, corned beef, and biltong or beef jerky as well as canned meat and meat-based preparations and sauces.
Below is IARC’s full Group 1 list – the things it says are definitely carcinogenic (red meat is not on this list, because it is only classified as a “probable” cause of cancer. The IARC splits these into three categories: “Carcinogenic exposure circumstances”, “Carcinogenic mixtures” and “Carcinogenic agents and groups of agents”. Tobacco smoking, the number one cause of cancer is first on the list, accounting for around 70% of global cancer deaths. Processed meats appear at No.39 in the list, and last in the “Carcinogenic mixtures” section.
Carcinogenic exposure circumstances
- Tobacco smoking
- Sunlamps and sunbeds
- Aluminium production
- Arsenic in drinking water
- Auramine production
- Boot and shoe manufacture and repair
- Chimney sweeping
- Coal gasification
- Coal tar distillation
- Coke (fuel) production
- Furniture and cabinet making
- Haematite mining (underground) with exposure to radon
- Secondhand smoke
- Iron and steel founding
- Isopropanol manufacture (strong-acid process)
- Magenta dye manufacturing
- Occupational exposure as a painter
- Paving and roofing with coal-tar pitch
- Rubber industry
- Occupational exposure of strong inorganic acid mists containing sulphuric acid
Carcinogenic mixtures
- Naturally occurring mixtures of aflatoxins (produced by funghi)
- Alcoholic beverages
- Areca nut - often chewed with betel leaf
- Betel quid without tobacco
- Betel quid with tobacco
- Coal tar pitches
- Coal tars
- Indoor emissions from household combustion of coal
- Diesel exhaust
- Mineral oils, untreated and mildly treated
- Phenacetin, a pain and fever reducing drug
- Plants containing aristolochic acid (used in Chinese herbal medicine)
- Polychlorinated biphenyls (PCBs) - widely used in electrical equipment in the past, banned in many countries in the 1970s
- Chinese-style salted fish
- Shale oils
- Soots
- Smokeless tobacco products
- Wood dust
- Processed meat
Carcinogenic agents and groups of agents
- Acetaldehyde
- 4-Aminobiphenyl
- Aristolochic acids and plants containing them
- Asbestos
- Arsenic and arsenic compounds
- Azathioprine
- Benzene
- Benzidine
- Benzo[a]pyrene
- Beryllium and beryllium compounds
- Chlornapazine (N,N-Bis(2-chloroethyl)-2-naphthylamine)
- Bis(chloromethyl)ether
- Chloromethyl methyl ether
- 1,3-Butadiene
- 1,4-Butanediol dimethanesulfonate (Busulphan, Myleran)
- Cadmium and cadmium compounds
- Chlorambucil
- Methyl-CCNU (1-(2-Chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea; Semustine)
- Chromium(VI) compounds
- Ciclosporin
- Contraceptives, hormonal, combined forms (those containing both oestrogen and a progestogen)
- Contraceptives, oral, sequential forms of hormonal contraception (a period of oestrogen-only followed by a period of both oestrogen and a progestogen)
- Cyclophosphamide
- Diethylstilboestrol
- Dyes metabolized to benzidine
- Epstein-Barr virus
- Oestrogens, nonsteroidal
- Oestrogens, steroidal
- Oestrogen therapy, postmenopausal
- Ethanol in alcoholic beverages
- Erionite
- Ethylene oxide
- Etoposide alone and in combination with cisplatin and bleomycin
- Formaldehyde
- Gallium arsenide
- Helicobacter pylori (infection with)
- Hepatitis B virus (chronic infection with)
- Hepatitis C virus (chronic infection with)
- Herbal remedies containing plant species of the genus Aristolochia
- Human immunodeficiency virus type 1 (infection with)
- Human papillomavirus type 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59 and 66
- Human T-cell lymphotropic virus type-I
- Melphalan
- Methoxsalen (8-Methoxypsoralen) plus ultraviolet A-radiation
- 4,4’-methylene-bis(2-chloroaniline) (MOCA)
- MOPP and other combined chemotherapy including alkylating agents
- Mustard gas (sulphur mustard)
- 2-Naphthylamine
- Neutron radiation
- Nickel compounds
- 4-(N-Nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK)
- N-Nitrosonornicotine (NNN)
- Opisthorchis viverrini (infection with)
- Outdoor air pollution
- Particulate matter in outdoor air pollution
- Phosphorus-32, as phosphate
- Plutonium-239 and its decay products (may contain plutonium-240 and other isotopes), as aerosols
- Radioiodines, short-lived isotopes, including iodine-131, from atomic reactor accidents and nuclear weapons detonation (exposure during childhood)
- Radionuclides, α-particle-emitting, internally deposited
- Radionuclides, β-particle-emitting, internally deposited
- Radium-224 and its decay products
- Radium-226 and its decay products
- Radium-228 and its decay products
- Radon-222 and its decay products
- Schistosoma haematobium (infection with)
- Silica, crystalline (inhaled in the form of quartz or cristobalite from occupational sources)
- Solar radiation
- Talc containing asbestiform fibres
- Tamoxifen
- 2,3,7,8-tetrachlorodibenzo-para-dioxin
- Thiotepa (1,1’,1”-phosphinothioylidynetrisaziridine)
- Thorium-232 and its decay products, administered intravenously as a colloidal dispersion of thorium-232 dioxide
- Treosulfan
- Ortho-toluidine
- Vinyl chloride
- Ultraviolet radiation
- X-radiation and gamma radiation
