An ingredient widely used in toothpaste and a range of food products can cause cancer, scientists have found.
The additive, titanium dioxide, caused precancerous growths in 40 per cent of rats that were given the chemical in their drinking water, according to researchers in France and Luxembourg. It also sped up the development of these growths, which are not malignant but can develop into more dangerous cancers.
The product, which is referred to as E171, is widely used in sweets, chocolate, biscuits and chewing gum, as well as toothpaste and sunscreen, to whiten products or make them look more opaque.
Previous research by the International Agency for Research on Cancer found inhaling titanium dioxide, which is also used in products such as paint, could cause cancer – but this is the first time such link has been shown when the product is consumed orally.
In the latest study, scientists found E171 was absorbed by the intestine and passed into the blood, where it spread to other parts of the body. Precancerous growths were found in the intestine or colon of 40 per cent of the rats exposed to the chemical, but in none of those that were given uncontaminated water. E171 was also found to weaken the rats’ immune system.
It is unclear whether the product might have a similar effect in people, and the scientists said their findings “cannot be extrapolated to humans”.
Despite this, the French government ordered an immediate inquiry into the safety of E171. This will take place as part of a wider investigation into the impact of nano-materials on health, and results will be published by the end of March.
In a joint statement, the French ministries for the economy, health and agriculture said: “A study carried out by the National Institute for Agricultural Research (INRA) and published today shows that oral exposure to titanium dioxide (E171), the additive used particularly in the agri-food industry, is likely to result in effects on health. However, at this stage, the results of the study do not make it possible to extrapolate to humans.
“In light of the findings of this study, the Ministries of Economy, Health and Agriculture decided to jointly refer the National Agency for Food, Environmental and Occupational Health Safety (Anses) to determine whether the food additive E171 presents a potential hazard to consumers."
13 ways to help prevent cancer
13 ways to help prevent cancer
Stopping smoking. This notoriously difficult habit to break sees tar build-up in the lungs and DNA alteration and causes 15,558 cancer deaths a year
Avoiding the sun, and the melanoma that comes with overexposure to harmful UV rays, could help conscientious shade-lovers dodge being one of the 7,220 people who die from it
A diet that is low in red meat can help to prevent bowel cancer, according to the research - with 30 grams a day recommended for men, and 25 a day recommended for women
Foods high in fibre, meanwhile, can further make for healthier bowels. Processed foods in developed countries appear to be causing higher rates of colon cancer than diets in continents such as Africa, which have high bean and pulse intakes
Two servings of fruit and three servings of vegetables a day were given as the magic number for good diet in the research. Overall, diet causes only slightly fewer cancer deaths than sun exposure in Australia, at 7,000 a year
Obesity and being overweight, linked to poor diet and lack of exercise, causes 3,917 deaths by cancer a year on its own
Dying of a cancer caused by infection also comes in highly, linked to 3,421 cancer deaths a year. Infections such as human papilloma virus - which can cause cervical cancer in women - and hepatitis - can be prevented by vaccinations and having regular check-ups
Cutting back on drinks could reduce the risk of cancers caused by alcohol - such as liver cancer, bowel cancer, breast cancer and mouth cancer - that are leading to 3,208 deaths a year
2014 Getty Images
Sitting around and not getting the heart pumping - less than one hour's exercise a day - is directly leading to about 1,800 people having lower immune functions and higher hormone levels, among other factors, that cause cancers
2011 Getty Images
Hormone replacement therapy, which is used to relieve symptoms of the menopause in women, caused 539 deaths from (mainly breast) cancer in Australia last year. It did, however, prevent 52 cases of colorectal cancers
2003 Getty Images
Insufficient breastfeeding, bizarrely, makes the top 10. Breastfeeding for 12 months could prevent 235 cancer cases a year, said the research
Oral contraceptives, like the Pill, caused about 105 breast cancers and 52 cervical cancers - but it also prevented about 1,440 ovarian and uterine (womb) cases of cancer last year
2006 Getty Images
Taking aspirin also prevented 232 cases in the Queensland research of colorectal and oesophagal cancers - but as it can also cause strokes, is not yet recommended as a formal treatment against the risk of cancer
The Independent has contacted the UK Department of Health for comment.
The study into the impact of titanium dioxide in rats was led by France’s National Institute for Agricultural Research (INRA) and published in the Scientific Reports journal.
The team gave rats E171 through their drinking water for 100 days. The quantities used were proportionally similar to those humans are exposed to through foods and cosmetic products
Publishing their findings, the researchers said: “These results indicate that E171 both initiates and promotes the early stages of colorectal carcinogenesis in animals.
“These studies show for the first time that the additive E171 is a source of titanium dioxide nanoparticles in the intestine and the entire body, with consequences for both immune function and the development of preneoplastic lesions in the colon.
“Oral exposure to E171 is a concern, especially in children who tend to eat a lot of sweets."