“Eating smoked foods increases the risk of cancer in humans.”

Consumption of processed meat was recently classified as carcinogenic to humans (Group 1), joining the individual dietary contaminants aflatoxin and aristolochic acid in that category.[19] Consumption of red meat was classified as probably carcinogenic to humans (Group 2A), and consumption of processed meat was classified as carcinogenic to humans (Group 1).[19] These classifications are based on sufficient (Group 1) or limited (Group 2A) evidence that these foods increase cancer risk in humans, particularly colorectal cancer.[19]

The Working Group of the International Agency for Research on Cancer classified the consumption of processed meat as carcinogenic to humans (Group 1), and classified red meat as probably carcinogenic to humans (Group 2A); consumption of both meat types is associated with an increased risk of colorectal cancer.[8] A large body of epidemiological studies have reported that the consumption of processed meats and red meats are risk factors for colorectal cancer (CRC).[8] The IARC working group concluded that for every 50 grams of processed meat or 100 grams of red meat eaten, the relative risk of colon cancer was increased by about 18% compared to those individuals who ate the least meats.[8]

Following an evaluation the International Agency for Research on Cancer (IARC) of the World Health Organisation (WHO) has classified red meat as probably carcinogenic to humans, placing it in Group 2A, and processed meat as carcinogenic to humans, placing it in Group 1.[12] “IARC has concluded that the evidence in favour of an association between processed meat consumption and cancer, probably because of the ingredients used in processing, meets their criteria for placing this class of foods on the list of recognised human carcinogens.”[12] This decision was based on evidence that high consumption of processed and red meat is associated with increased colorectal cancer risk in humans.[12]

Smoked fish and meat products may be contaminated by various toxic compounds including carcinogenic compounds. Polycyclic aromatic hydrocarbons (PAHs), which are a group of organic compounds known to be carcinogenic, are formed during incomplete combustion of organic matter and are present in smoke used for smoking meat and fish. The presence of PAHs, N-nitrosamines and other toxic compounds in smoked products raises health concerns, since many of these compounds are mutagenic and carcinogenic in humans and animals.

Group 1: The agent is carcinogenic to humans. This category is used when there is sufficient evidence of carcinogenicity in humans.[4] Processed meat was classified as carcinogenic to humans (Group 1), and red meat was classified as probably carcinogenic to humans (Group 2A).[10] These classifications reflect the strength of evidence that these exposures can cause cancer, not the magnitude of the risk.[4]

In 2015, an independent panel of experts convened by the International Agency for Research on Cancer (IARC) determined consumption of red meat to be “probably carcinogenic to humans” (Group 2A), based largely on data from the epidemiologic studies and on the strong evidence from mechanistic studies. It also determined processed meat to be “carcinogenic to humans” (Group 1), based on sufficient evidence of CRC from epidemiologic studies. The World Cancer Research Fund/American Institute for Cancer Research issued a report in 2007 with dietary guidelines that recommended limiting the consumption of red and processed (including smoked) meats.

"Processed meat intake (usually including sausages, meats burgers, ham, bacon, salami, nitrite-treated meat and meat products) is associated with CRC risk in all reports: Global RR are 1.49 (CI: 1.22–1.81), 1.31 (CI: 1.13–1.51) and 1.20 (CI: 1.11–1.31) in the three meta-analyses." "The fact that processed meat intake increases colorectal cancer risk seems established from the published meta-analyses of epidemiologic studies." "However, the excess risk per gram of intake is clearly higher than that of fresh red meat."

"PAHs, especially those with higher molecular weights like benzo[a]pyrene (B[a]P), are classified by the International Agency for Research on Cancer (IARC) as Group 1 carcinogens, meaning they are known to cause cancer in humans." "Studies have shown a strong correlation between PAH exposure and the increased incidence of cancers, particularly those of the lung, skin, bladder, and gastrointestinal tract." "Similarly, research has suggested that exposure to PAHs through grilled meat may increase the risk of prostate cancer, breast cancer, and even pancreatic cancer, especially in individuals who have high levels of PAH exposure due to frequent consumption of grilled or smoked foods."

The new IARC report places processed meats (hot dogs, bacon, ham, sausage, cold cuts) in Group 1: Carcinogenic to Humans, the same category as cigarettes.[13] Red meat (beef, pork, lamb) is assigned to Group 2A: Probably Carcinogenic to Humans.[13] Although WHO now classifies both processed meat and cigarettes in the highest category of carcinogen, these classifications reflect the strength of the evidence behind them, not the level of risk.[13]

Evidence shows that even small amounts of processed meat eaten regularly increase the risk of colorectal cancer. Compounds in processed meat tied to cancer are produced from smoking, curing, and nitrate- or nitrite-based additives. Laboratory studies show that when meat is smoked, cured, salted or has added nitrites, compounds form that can cause cancer. Smoked meat contains compounds called PAHs (polycyclic aromatic hydrocarbons).

Eating red and processed meat has been linked to an increased risk of cancer. Eating red and processed meat is linked to a higher risk of colorectal cancer. These meats may also increase the risk of breast, pancreatic, prostate, and stomach cancer, but more research is needed. Processed meat is meat that has been preserved by smoking, curing or salting, or by the addition of preservatives.

"PAHs are associated with risks to human health, especially carcinogenesis." "Protein products (fish and meat), which are smoked and dried or thermally cooked (grilled, roasted or fried), are a main source of polycyclic aromatic hydrocarbons." "These beef and pork products displayed PAHs levels above those deemed acceptable, thus posing a risk to consumers."

"Some of these PAHs have potential roles in carcinogenesis of colorectal cancer (CRC)." "The International Agency for Research on Cancer (IARC) pronounced red and processed meat to be Group 1 carcinogens and suggested that polycyclic aromatic hydrocarbons are causative compounds to CRC." "This study demonstrated a link between PAH compounds in processed meat and alteration of colorectal cancer genes."

The WHO's International Agency for Research on Cancer (IARC) has indicated that there is sufficient evidence to categorize processed meats as group 1 carcinogens due to a direct association with bowel cancer.[15] Red meat is classified in group 2A, which suggests it is 'probably carcinogenic to humans.'[15] Their experts determined that consuming an additional 50 grams of processed meat daily raises the likelihood of developing colorectal cancer by 18%.[15]

The National Cancer Institute warns that both HCAs and PAHs are mutagenic, meaning they can cause changes to your DNA that put you at risk for certain types of cancer. “High exposure to these compounds can lead to increased risk of cancer of the intestinal tract, notably colon and stomach cancer,” Culbertson says. “Some recent research also suggests that red and processed meats, including smoked meats, may increase your risk of breast and prostate cancer.” In fact, the World Health Organization (WHO) has classified processed meat — which includes smoked meat — as a Group 1 carcinogenic based on evidence of its link to colorectal cancer.

"PAHs are a class of chemicals that have been shown by numerous studies to have toxic, genotoxic, mutagenic and carcinogenic effects on the human body." "Meat cooked at high temperatures, in direct contact with flames or smoke (such as grilled or smoked meat), is among the main dietary sources of PAHs." "Epidemiological studies have associated high intake of heavily browned or smoked meat with increased risks of colorectal and other cancers, although results are not entirely consistent."

Examples of agents classified as Group 1 include tobacco smoke, alcoholic beverages, Chinese-style salted fish and consumption of processed meat.[5] Group 1: The agent is carcinogenic to humans. There is sufficient evidence of carcinogenicity in humans.[5] IARC identifies carcinogenic hazards based on qualitative assessment of animal and human evidence; the classification is based only on the strength of evidence for carcinogenicity, not on the relative increase of cancer risk or the amount of exposure necessary.[5]

Epidemiological studies indicates a statistical correlation between the increased occurrence of cancer of the intestinal tract and the frequent intake of smoked foods. Higher frequency of smoked food intake has been associated with greater incidence of gastric and colon cancers in several populations where smoked foods are commonly consumed. These observations suggest that smoked food consumption may be an etiological factor in human gastrointestinal cancer.

"Thermal treatment of high-protein food may lead to the formation of mutagenic and carcinogenic compounds, e.g., polycyclic aromatic hydrocarbons and heterocyclic aromatic amines." "Protein products (fish and meat), which are smoked and dried or thermally cooked (grilled, roasted or fried), are a main source of polycyclic aromatic hydrocarbons." "A high consumption of meat products is associated with an increased risk of cancer. The increased risk may be due to the high content of fat, protein or the formation of carcinogenic compounds, including heterocyclic aromatic amines and polycyclic aromatic hydrocarbons when processing meat at high temperatures."

Benzo[a]pyrene (BaP) has been identified by the International Agency for Research on Cancer as a **Group 1 carcinogen**, meaning it is known to cause cancer in humans.[4] Other PAHs like benz[a]anthracene, chrysene, and benzo[b]fluoranthene are classified as **possible human carcinogens**.[4] Studies have shown that **high consumption of well-done, fried, or barbecued meats was associated with increased risks of colorectal, pancreatic, and prostate cancer**, though researchers note that establishing definitive links in humans is challenging because people are exposed to PAHs from multiple sources.[4]

Red and processed meat intake may increase lung cancer risk. In conclusion, higher frequencies of intake of fresh red meats and processed meats were independently associated with increased lung cancer risk in this Italian population. Processed meats include products preserved by smoking, curing, salting, or addition of chemical preservatives, and the study found positive associations with lung cancer incidence after multivariable adjustment.

"Known for their mutagenic, carcinogenic, and genotoxic properties, PAHs can inflict DNA damage through their metabolites, potentially leading to mutations and cancer." "Eating traditional Chinese smoked pork may pose health risks." "Most of the smoked pork samples indicated a potential carcinogenic risk, especially in the outer sections."

The IARC classifies the substances it has evaluated into various groups according to the overall strength of evidence based on cancer hazard derived from studies in humans and in experimental animals and other relevant data.[7] Group 1: Carcinogenic to humans – Sufficient evidence in humans – e.g.: aflatoxins, alcoholic beverages, benzo[a]pyrene, cadmium, Chinese-style salted fish, chromium (VI) compounds, dioxins and dioxins-like PCBs, and processed meat.[7] Group 2A: Probably carcinogenic to humans – Evidence is limited in humans but sufficient in experimental animals – e.g.: acrylamide, inorganic lead compound, and red meat.[7]

Cells and animals aren’t people, but some epidemiological studies have also linked the consumption of smoked meats to intestinal cancer. For example, in one region of Hungary where home-smoked foods are a major part of the diet, the incidence of stomach cancer is twice that in the rest of the country. Besides the carcinogens already present in smoke, the heat associated with smoking can also result in chemical reactions in the meat that form yet more carcinogens such as acrylamide, acrolein and nitrosamines.

Heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs), which are classified as **probable carcinogens by the U.S. Environmental Protection Agency**, are chemicals that form when meat is cooked at the high temperatures that occur during grilling.[17] HCAs and PAHs are chemical compounds that are formed when red meats are cooked at high temperatures and are **very well done**.[17] HCAs and PAHs are **linked to increased cancer risk for colon, breast, pancreatic and other cancers**, and PAHs are present in the smoke from open flames that can deposit on the surface of smoked or grilled meat.[17]

The result of unconditional logistic regression analysis demonstrated that fried food and smoked food were risk factors of lung cancer. Compared with the people whose smoked food intake <3 times/week, the people whose smoked food intake ≥3 times/week had a 6.774-fold increased lung cancer risk (95% CI 3.309–13.866). The intake of fried food and smoked food are independent risk factors of lung cancer.

The International Agency for Research on Cancer (IARC), part of the World Health Organization, classifies consumption of processed meat as Group 1: carcinogenic to humans — the same highest category as tobacco smoking, asbestos, alcohol consumption, and ultraviolet radiation.[2] The Group 1 label is based on sufficient evidence from human epidemiological studies (over 800 reviewed) showing that processed meats — including ham, bacon, hot dogs, sausages, salami, and other cured, salted, smoked, or nitrite-preserved products — cause colorectal cancer.[2] Processed meats include "other cured, salted, smoked, or nitrite-preserved products," indicating that smoking is one of the processing methods associated with the carcinogenic classification.[2]

Grilled, barbecued, and smoked meat intake, a prevalent dietary source of polycyclic aromatic hydrocarbon (PAH) carcinogens, may increase the risk of incident breast cancer. In this population-based prospective study of grilled/barbecued and smoked meat intake and mortality among a cohort of women diagnosed with first primary breast cancer, high prediagnosis annual intake of total grilled/barbecued and smoked meat was statistically significantly associated with an elevated risk of all-cause mortality. High intake of grilled/barbecued and smoked meat may increase mortality after breast cancer.

"Total PAH concentrations in smoked meat products ranged from 2.6 micrograms/kg in a cooked ham sample to 29.8 micrograms/kg in grilled pork chops, while those in fish products ranged from 9.3 micrograms/kg in smoked shrimp to 86.6 micrograms/kg in smoked salmon." "Total concentrations of the carcinogenic PAHs (benzo[a]anthracene, benzo[b]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene, and indeno[1,2,3-c,d]pyrene) ranged from non-detectable in several meat products to 7.4 micrograms/kg in grilled pork chops, and from 0.2 micrograms/kg in trout to 16.0 micrograms/kg in salmon."

High intake of grilled, barbecued and smoked meat by women who survive breast cancer may increase their risk of mortality. When considering post-diagnosis changes in intake, the researchers observed that women who continued to consume large amounts of grilled, barbecued and smoked meat after diagnosis had a 31 percent increased risk of all-cause mortality, compared to those who reduced their intake. The study supports previous findings that high consumption of smoked and grilled meats may be associated with adverse health outcomes, including cancer-related mortality.

Most importantly, the **highly carcinogenic benzo[a]pyrene remained undetected in all of the sugar-smoked meat samples**.[13] In addition, the **cancer risk due to dietary PAH exposure based on total intake of meat in Taiwan was <2 × 10^–7**, indicating a very low estimated risk under the conditions studied.[13] The study shows that modified smoking methods (sugar-smoking) can significantly reduce PAH levels in smoked meat and therefore potential carcinogenic risk.[13]

Chinese-style salted fish, traditionally prepared by salting and drying in open air, was evaluated by IARC and classified as carcinogenic to humans (Group 1), with sufficient evidence for nasopharyngeal carcinoma from studies in southern China and Southeast Asia.[11] This food is both salted and often exposed to smoke or high-temperature drying, leading to formation of carcinogenic N-nitroso compounds and other chemicals.[11] The classification indicates that a specific smoked/salted food has been determined to cause cancer in humans based on epidemiological evidence.[11]

“Meat consumption is not tobacco smoking”, and of course, the mass-media should not publish sensational headlines with messages suggesting that processed red meats can kill as tobacco smoking do it, based on the fact that both are classified by IARC in the Group 1.[9] The authors emphasise that IARC classifications refer to the strength of evidence for carcinogenicity, not to the level of risk, and processed meat has a much lower relative risk compared to tobacco smoking.[9] They note that processed meat (which can include smoked and cured meats) was classified as carcinogenic to humans due to its association with colorectal cancer, but the magnitude of risk is modest.[9]