Myths and controversies about what causes cancer
We explore the rumours, fiction, media reports and urban legends about whether everyday products increase cancer risk
Read more on Plastic bottles and cling film; Artificial sweeteners; Psychological stress; Cosmetics and toiletries; Breast implants; Underwire bras; Organic food; Hormones in cattle; Food additives; Coffee; Burned or browned foods (acrylamide); Tap water
There are claims that chemicals in plastic drinks bottles, cling film and food containers can cause cancer by seeping into the contents. While some studies have shown that a very small amount of chemicals in plastic packaging can get into drinks or food when heated, these amounts have been well within safe limits – which are very strictly regulated in the UK.
There is no reliable evidence that using plastic bottles to drink from, or cling film to store or freeze food, increases your risk of cancer. However, if you are using plastic utensils while cooking, the best thing to do is to follow the directions and only use plastics that are specifically meant for cooking. Inert containers, such as heat-resistant glass, ceramics and stainless steel, are preferable for cooking.
But the risk of using plastics for cooking is very small. Not smoking, followed by maintaining a healthy weight through eating a healthy diet and keeping active, are the most effective ways to reduce your cancer risk.
Studies on artificial sweeteners, including saccharin and aspartame, have shown no convincing evidence of an association with cancer. Earlier cancer scares linked with certain sweeteners have been discredited.
Some people have suggested a link between psychological stress (which is what people experience when under mental, physical or emotional pressure) and an increased risk of cancer. However, there is no strong evidence for this. Most studies have not found that such stress increases the risk of cancer.
However, people under stress can sometimes behave in unhealthy ways, such as smoking, overeating or drinking heavily, which do increase their risk of many cancers. If you’re under stress, it’s important to try to find other ways of coping, such as doing physical activity.
Most studies have found no link between cancer and the chemicals used in cosmetic and toiletry products such as moisturisers, shampoos, deodorants, and toothpastes. The majority of countries have strict regulations to ensure these products are safe.
Some studies have found a link between talcum powder (talc) and ovarian cancer, but there is not enough evidence to be certain of this. Even if there were an increased risk, scientists estimate it would be small. Not smoking, followed by maintaining a healthy weight through eating a healthy diet and keeping active, are the most effective ways to reduce your cancer risk.
There have been many studies into whether silicone leakage from breast implants increases the risk of breast cancer. None of them so far have found any evidence that this is the case. Not smoking, followed by maintaining a healthy weight through eating a healthy diet and keeping active, are the most effective ways to reduce your cancer risk.
The majority of research has found no link between the use of underwire bras and breast cancer. Not smoking, followed by maintaining a healthy weight through eating a healthy diet and keeping active, are the most effective ways to reduce your cancer risk.
Organic farming makes use of crop rotation, environmental management and good animal husbandry to control pests and diseases. This means that there are limited additives used in organic food production. Processed organic foods use ingredients that are produced organically, and for a food to be certified organic, at least 95% of the food must be made up of organic ingredients.
There are many different reasons why consumers choose to buy organic food, such as concern for the environment and animal welfare. Consumers may also choose to buy organic food because they believe it is safer and more nutritious than other food and that artificial fertilisers and pesticides may increase the risk of some diseases, including cancer.
However, there is currently no strong evidence to support the idea that organic foods offer added protection against cancer compared to conventionally grown produce.
Research shows that eating a healthy diet, along with not smoking and keeping active, are very important in cancer prevention, but choosing fresh, frozen, canned, conventional or organic produce does not affect your cancer risk.
Both organic and conventional food have to meet the same legal food safety requirements. Before pesticides are approved they are rigorously assessed to ensure they do not pose an unacceptable risk to human health or the environment, and that any pesticide residues left in food will not be harmful to consumers.
Pesticide residues in the food chain are also monitored to check they are within legal and safe limits. Additives are also subject to rigorous, pre-market safety assessments before they can be used in foods. Their use is controlled by legal limits, which ensures consumption does not exceed safe levels.
Legislation about hormones in cattle varies from country to country. For example, growth hormones are used in dairy farming in the US, whereas the use of hormonal growth promoters for livestock is banned in the UK. Antibiotic growth-promoting feed additives have also been phased out due to concerns about the potential spread of antibiotic resistance.
Bovine somatotropin (or BST) is a hormone used to increase milk or meat production in cattle and is banned in the UK and Europe but is licensed in the US. BST was banned on animal welfare grounds, not because there is any proven effect on human health. A EU Scientific Committee report has stated that there is no scientific evidence that this hormone is a health risk.
Milk is rigorously tested for traces of antibiotics under European law to ensure that food is safe for consumption. Cows receiving antibiotics are milked separately from the rest of the herd to ensure that the milk is discarded and does not enter the food supply.
In the UK, the Food Standards Agency regulates the content of milk and other dairy products to ensure these products are safe to consume.
Not smoking, followed by maintaining a healthy weight through eating a healthy diet and keeping active, are the most effective ways to reduce your cancer risk. Research shows that eating too much red meat, and any amount of processed meat, increases the risk of bowel and stomach cancer. For cancer prevention, it is best to eat no more than 500g (cooked weight) a week of red meat, such as beef, pork and lamb, and to eat little, if any, processed meat, such as ham and bacon.
Food additives are ingredients added to foods for various reasons – for example, to add colour, enhance flavours or to make them last longer. All additives, including artificial sweeteners, are assessed for safety before they are used in foods. An E number is a reference number given to food additives that have passed safety tests and have been approved for use in the UK and throughout the European Union.
The only additives for which evidence has shown a link with cancer are nitrites and nitrates, which are used as preservatives in processed meat. Eating processed meat is strongly associated with an increased risk of bowel and stomach cancer.
There is currently no other strong evidence linking food additives to an increased cancer risk.
There is no strong evidence that coffee increases cancer risk, but there is strong evidence that coffee can actually reduce the risk of womb (endometrial) and liver cancer. However, we cannot make any specific recommendations because there are too many unanswered questions – for example, are the benefits a result of drinking coffee regularly, or in large amounts? There is also no evidence on the effects of adding milk and/or sugar, or on drinking caffeinated, decaffeinated, instant or filter coffee.
For general health, research from the European Food Safety Authority (EFSA) shows it is safe for healthy adults, including pregnant women, to drink single doses of up to 200mg of caffeine. Drinking up to 400mg of caffeine through the day does not raise safety concerns in the general population, which is equal to around four cups of filter coffee a day.
The UK’s Food Standards Agency has recommended that foods with a high starch content, such as bread, chips and potatoes, should be cooked to a golden yellow colour, rather than brown, to reduce intake of a chemical that has been associated with causing cancer in mice.
Acrylamide is present in many different types of food and is a natural by-product of the cooking process. The highest levels of the substance are found in foods with high-starch content which have been cooked above 120C, such as crisps, bread, breakfast cereals, biscuits, crackers, cakes and coffee (as a result of the roasted beans).
It can also be produced during home cooking, when high-starch foods – such as potatoes, chips, bread and parsnips – are baked, roasted, grilled or fried at high temperatures. When bread is grilled to make toast, for example, this causes more acrylamide to be produced. The darker the colour of the toast, the more acrylamide is present.
However, the research linking acrylamide to cancer has only been carried out using animals. The World Cancer Research Fund has carried out a review of studies in people, and found no link between acrylamide in food and cancer. More research is needed but, in the meantime, maintaining a healthy weight and eating a healthy diet – which includes eating fewer high-calorie foods such as crisps, chips and biscuits – together with not smoking and keeping active, are the most effective ways to reduce your cancer risk.
Research has found that drinking water contaminated with arsenic increases the risk of skin, lung and bladder cancer. Water contaminated with arsenic is not a public health issue in the UK, although it does affect some other countries that have high natural concentrations of arsenic in soil.
In the UK, the Drinking Water Inspectorate is responsible for checking the quality of water, based on guidance from the World Health Organization. Strict measures are in place to make sure that levels of chemicals meet safe standards.
Public Health England monitors the effects of water fluoridation on health. To date, there is no evidence of a difference in the rate for all types of cancer between fluoridated and non-fluoridated areas.
Water is a healthier choice than many other drinks, particularly compared with those high in sugar and calories, which can contribute to weight gain. Not smoking, followed by maintaining a healthy weight through eating a healthy diet and keeping active, are the most effective ways to reduce your cancer risk.
Cosmetics and toiletries
Hormones in cattle
World Cancer Research Fund (pdf, plus abstract)