People panic whenever a rumor comes out that something or food causes cancer, people refrain from eating soy claiming that it causes breast cancer, and hate plastic dishes because they leak toxic substances into food, and do not eat dark fried potato tips because they contain a carcinogen that they do not know the name of. The truth is that cancer is a complex disease, where environmental factors intertwined with genetic traits and aging cause the occurrence of different cancers, numbering up to 100 types, each representing an independent disease.

Rumors of this kind usually appear as a result of focusing on incomplete or false information, and exaggerating it and presenting it as undoubted facts, the problem is that confirming this type of information may not be easy for non-specialists, so we present here a simplified scientific refutation of some of the most famous rumors about the causes of cancer.

Burnt food

It was rumored at one time that eating burnt ends of fries or toast was dangerous and caused cancer, but rumors did not identify any type of cancer. Acrylamide consists of the reaction of sugar with an amino acid called asparagine, both of which are naturally found in some vegetables and grains, when exposed to high temperatures during frying or grilling, and are the cause of the appearance of burnt brown limbs (1). This substance is also used in the manufacture of paper, dye, plastics, water and sewage treatment, and is even found in tobacco (2). In the body, acrylamide is converted into glycidamide, a DNA toxic compound capable of destroying and mutating it (3).

The burnt ends of french fries contain higher amounts of acrylamide. (Shutterstock)

In research on the effect of this substance on cells, two published studies in 1988 and 2012, conducted on samples of rodents, found that high intake of acrylamide increased the chances of lung and stomach cancer, but did not provide sufficient evidence that acrylamide is capable of causing the same effect in humans (4)(5). It is worth noting here that studying the effect of acrylamide on rodents does not necessarily reflect its effect on human cells, as the quantities provided to rodents under experiment are very large, higher than what humans may consume of food naturally, and human cells are less reactive to glycidamide than the cells of mice and rats (6)

However, the U.S. Department of Health and Human Services' National Toxicology Program report on carcinogens places acrylamide on lists of "probable" carcinogens based on the results of rodent studies (7). The Food and Drug Administration has also declared acrylamide a substance "may be carcinogenic", developed warnings and regulations to limit its percentage in industries, and developed guidelines to limit its consumption of household food (8). So there's still no conclusive evidence that acrylamide causes cancers in humans, but animal experiments have been enough to put it on potential risk lists, but eating a piece of burnt potato or bread is unlikely to get cancer anyway.

Infamous soybeans

For 9000 years, soybeans have been present on the tables of human beings, first in China, then the Americas, and then the rest of the world, and is - economically - the most important types of beans in the world, thanks to its high nutritional value, and its content of protein and fat, which makes it an almost ideal alternative to animal protein (9). But in modern times, soybeans or their derivatives are mentioned only with a lot of caution and anticipation, thanks to what has been rumored to cause some cancers and affect male hormones, and this claim has a real basis but only half the truth.

Soybeans contain a substance similar to human estrogen called isoflavone or phytoestrogen, which is the source of all concerns surrounding soybean consumption (10). The hormone estrogen is found naturally in both males and females but in varying proportions, and is responsible for regulating several vital processes in the body, such as the appearance of secondary sexual characteristics in females, the regulation of desire and erection in males, heart and bone health in both sexes, and plays an important role in the formation and growth of cancer cells in the breast (11).

When exposed to estrogen for long periods, the chance of breast cancer increases in women, especially if there is a family history of this type of cancer (12). Soybean warriors argue that exposure to phytoestrogens has the same effect and increases the risk of breast cancer, and this claim is based on the morphological similarity between the two compounds, without considering the real effect that phytoestrogen has inside the body, and other associated factors such as age, race, and the rate of soybean consumption in the diet (13).

One study found that eating soy in moderation had no effect on breast cancer incidence, while eating large amounts of soy may have a cancer-preventing benefit. (Pixaby)

Contrary to these concerns, some studies have found that regular soy intake has a protective effect against breast cancer in women. In a Chinese meta-study of 300,14 women who consumed soy regularly, it was found that eating soy in moderation had no effect on the incidence of breast cancer, while eating large amounts of soy may have a preventive benefit from cancer (15). This finding is supported by another meta-analysis recently published in the journal In Vivo, which focused on analyzing previous studies that monitored soy consumed and compared it to breast cancer incidence or non-incidence rates, and ultimately concluded that eating soy in large quantities reduces the chances of being diagnosed with breast cancer in women (<>).

It is worth noting that studies that found a positive effect of phytoestrogen on the growth of cancer cells were done on rodents and not humans, and until science finds strong evidence in humans, you can safely eat soy one to two times a day, in addition to some other foods that also contain phytoestrogens such as legumes, chickpeas, flax seeds and sesame.

Cancer in my diet

The chain of rumors does not stop here, there are still many food products that are rumored to cause cancer, such as the famous instant noodles "Indomie", and ready-made broth cubes as well. These foods contain monosodium glutamate, a taste-enhancing substance added to food to give it a distinctive flavor. Recently, this substance has been responsible for adding a fifth to the four main tastes that the human tongue can taste (sweet, bitter, salty, and sour), umami, which refers to the rich taste of protein, which MSG imparts to food (16).

MSG is extracted from the fermentation of sugar cane or corn, so you may find products containing them classified as "natural products", also found naturally in tomatoes, mushrooms and cheeses, and heat releases them from their bonds to circulate in food and give it a rich umami taste. Maybe that's why you find yourself eating instant noodles so much, and you miss them all the time, and maybe that's also why a small broth cube can turn a soup made with plain water into a delicious and rich soup.

Eating a plate of instant noodles every once in a while won't be a big deal, although we don't recommend overeating it because it's not a healthy or balanced meal anyway. (Pixaby)

MSG has been studied intensively over the years to determine whether taking it poses a health threat and whether it increases the risk of cancer, without reaching conclusive results. For example, a study published in the journal Toxicology and Environmental Health Sciences of the Springer Foundation, which was conducted on workers in the manufacture of MSG as the most exposed groups, did not determine that there were adverse effects on health as long as exposure to the substance was within the permissible limits (17).

On the other hand, a more recent study, published in the journal Environmental Science and Pollution Research, found that MSG was toxic to the heart muscle in white mice that consumed it in large quantities, while there was no indication of its effect on humans or causing cancers (18).

It should be noted that despite the absence of conclusive evidence that MSG causes cancers, there is a small group of people who are allergic to this substance, and its consumption can cause some symptoms such as headache, high blood pressure and redness of the skin, but it does not cause more serious symptoms (19), so eating a plate of instant noodles every once in a while will not be a big problem, although we do not recommend overeating it because it is not a healthy or balanced meal anyway.

Smells and colors

Exposure to hair dyes at intervals does not carry a risk of cancer. (Pixels)

Cancer rumors are not limited to food only, but extend to what we put on our bodies and hair as well, and the most famous personal care products that have gained a reputation for causing cancer are deodorants and hair dyes, and some claims against these products confuse some facts with some rumors, and a little research can confirm their truthfulness.

Hair dyes contain "aromatic amines" compounds that have been found to be able to cause various cancers, especially in older dyes, especially dark-colored dyes. In the last three decades, dye manufacturers have changed their composition to produce safer ones, but the charge of carcinogenicity has continued to haunt them (20). But a few other factors need to be taken into account: not every exposure to aromatic amines necessarily means cancer.

First of all, we have to point out that most of the studies that have found a link between exposure to aromatic amines and bladder cancer have been done in rats, after exposure to large amounts of them for a long time. But in reality, if you are used to using hair dyes, the chances of developing bladder, breast or blood cancer are still low, because the percentage of exposure to aromatic amines is low compared to, for example, workers in dye factories or barbershops and beauty salons, who are exposed to dye fumes for long periods.

The latter group is already more likely to develop cancer as a result of exposure to aromatic amines through prolonged breathing and skin in large quantities, and it is the most careful group of clients who come once or twice a year to dye their hair, or who dye their hair themselves at home (21).

There is still no conclusive evidence that aluminum-containing deodorants cause breast
cancer (Deutsche Welle)

In the same category, deodorants stand in the dock, especially those containing aluminum compounds, and in a world where breast cancer is the second most common cancer in the world, it must be present in every fact and myth. The fear that deodorants cause breast cancer came from the fact that the armpit site is close to the outer upper quadrant of the breast, which is the most famous site for breast cancer, hence studies have sought to refute this claim (22).

Aluminum compounds are used in various removers for their ability to clog sweat pores, stop its flow for a while, and it is believed that they can manipulate the DNA of breast cells, or affect the hormone estrogen, which plays a role in the occurrence of breast cancer. However, none of the studies that attempted to link the two found conclusive evidence, including a newly published statistical analysis in the Journal of Cosmetic Dermatology, which analyzed the results of six case- control studies, and found no evidence that the use of aluminum-compound deodorants can cause breast cancer (6).

Leaky vehicles

Talking about potential carcinogens cannot pass without mentioning the most prevalent industrial material on earth, plastic! Plastic is a difficult material to form, and to give it flexibility, a material called phthalates is added that makes it easier to mold it. These substances can seep into food and drink placed inside a plastic container if exposed to heat or microwave radiation, as well as BPA, which is used in the manufacture of water bottles and lining metal food cans (24).

Both substances belong to the group of "endocrine-disruptive chemicals", which are substances capable of manipulating and disrupting the functioning of the body's endocrine glands, which can lead to some types of cancers (25). BPA in particular has an effect similar to estrogen, making it a source of concern for women, especially those with a family history of breast cancer. Hundreds of studies have been conducted on the danger of these substances and their impact on human health, especially with the incursion of plastic products into daily life, and some of them have already found alarming results.

Do not drink water from a plastic bottle that has been exposed to the heat of the sun. (Shutterstock)

One of the most recent studies is Meta Analysis published in the journal Reproductive Toxicology, which analyzed nine previous studies on the relationship of thalites to breast and uterine cancers and found that there was no clear relationship between these cancers and the total thalites broken down in the urine. However, by isolating the breakdown products, one of them, called DEHP, was found to have a strong association with both types of cancer, meaning there is a possibility that exposure to large amounts of this substance may increase the risk of breast and uterine cancers (9).

On the other hand, determining the maximum safe exposure to BPA is still controversial and researched, due to the combination of multiple factors, such as the interaction of BPA with other compounds in plastics, or the individual's sensitivity to the substance, the duration of exposure, and the general health status (27), but until this moment, the US Food and Drug Administration (FDA) still considers this substance safe for consumption in small quantities (28). We are faced with the problem that there are not enough studies on the extent to which the Arab citizen is specifically exposed to these substances, so there is no real value to the maximum exposure without taking local factors into account.

Until newer studies take into account the conditions of Arab citizens, exposure to these substances in small quantities is safe. To ensure this, avoid heating plastic containers in the microwave, placing water bottles in direct sunlight or leaving them in the car, as well as reducing the consumption of food stored in metal cans, and whenever possible, replace plastic containers with glass or stainless metal containers.

People tend to believe rumors if they agree with their previous cognitive biases, or if these rumors play on their fear and anxiety, or even just because the source of the information is a celebrity without regard for her medical background, which makes some overestimate concerns about certain foods and materials that we use in our lives. On the contrary, many people do not mind exposure to environmental causes that have already been proven to be associated with various cancers, they do not stop smoking or exposure to tobacco smoke that causes lung and laryngeal cancers, they do not care about using sunscreen that causes skin cancer, and they may walk on streets filled with car exhaust that they inhale daily without worry, despite strong evidence that it is indeed a carcinogen.

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Sources:

  • 1- Acrylamide | FDA
  • 2- Acrylamide and Cancer Risk
  • 3- Acrylamide and Cancer Risk – NCI
  • 4- Acrylamide: its metabolism, developmental and reproductive effects, genotoxicity, and carcinogenicity
  • 5- Toxicology and carcinogenesis studies of acrylamide (CASRN 79-06-1) in F344/N rats and B6C3F1 mice 
  • 6- Toxicokinetics of acrylamide in humans after ingestion of a defined dose in a test meal to improve risk assessment for acrylamide carcinogenicity
  • 7- RoC Profile: Acrylamide
  • 8- Acrylamide | FDA
  • 9- Soybean | Description, Cultivation, Products, & Facts 
  • 10- Can Soy Cause Breast Cancer?
  • 11- Estrogen: Hormone, Function, Levels & Imbalances
  • 12- Types of Breast Cancer: Triple Negative, ER-Positive, HER2-Positive
  • 13- Effects of Dietary Phytoestrogens on Hormones throughout a Human Lifespan: A Review
  • 14- Soy intake and breast cancer risk: a prospective study of 300,000 Chinese women and a dose-response meta-analysis
  • 15- Soy Isoflavones and Breast Cancer Risk: A Meta-analysis
  • 16- 16 Healthy Foods Packed with Umami Flavor
  • 17- Toxicological evaluation of MSG for the manufacturing workers’ health: A literature review 
  • 18- Monosodium glutamate induces cardiac toxicity via oxidative stress, fibrosis, and P53 proapoptotic protein expression in rats
  • 19- Sensitivity to food additives, vaso-active amines and salicylates: a review of the evidence
  • 20- Does Hair Dye Increase Cancer Risk?
  • 21-Hair Dyes and Cancer Risk
  • 22- Antiperspirants Facts About Cancer, Aluminum, Alzheimer’s, and More
  • 23- Aluminum‐containing antiperspirants are not associated with breast cancer – Osto – 2022 – Journal of Cosmetic Dermatology
  • 24- What is BPA? Should I be worried about it?
  • 25- Co-exposure to BPA and DEHP enhances susceptibility of mammary tumors via up-regulating Esr1/HDAC6 pathway in female rats
  • 26- Association between urinary phthalate metabolites and risk of breast cancer and uterine leiomyoma 
  • 27- Bisphenol A co-exposure effects: A key factor in understanding BPA’s complex mechanism and health outcomes
  • 28- What is BPA? Should I be worried about it? – Mayo Clinic