An additive commonly found in toothpaste, sweets and chewing gum could cause cancer, scientists have warned.
Titanium dioxide (E171) was found to cause growths in 40% of rats that were fed the additive in drinking water.
While these growths weren’t cancerous initially, they have the potential to develop into something more dangerous, researchers said.
The findings come just one day after the Food Standards Agency (FSA) warned that roasting and frying starchy foods - such as potatoes - could increase the risk of cancer.
Titanium dioxide is used as a white pigment in many foods.
In a new study, published in the journal Scientific Reports, researchers from France’s National Institute for Agricultural Research (INRA) gave rats the additive via their drinking water for 100 days.
The amount of titanium dioxide they consumed was similar to the amount humans are exposed to on a daily basis through foodstuffs.
Scientists discovered that almost half (40%) of the rats who consumed E171, as opposed to uncontaminated drinking water, developed precancerous growths in their intestines or colons.
The additive was also found to weaken their immune systems.
Researchers said it is unclear whether the results would be similar in humans, and suggested more research was needed to determine the health implications of E171 further.
They concluded: “These data should be considered for risk assessments of the susceptibility to Th17-driven autoimmune diseases and to colorectal cancer in humans exposed to TiO (titanium dioxide) from dietary sources.”
In response to the findings, Dr Helen Webberley, the dedicated GP for Oxford Online Pharmacy, said we shouldn’t go throwing out our toothpaste (or sweets, or chewing gum) just yet.
“We need to take stock,” she told The Huffington Post UK. “This study was carried out on rats, with titanium dioxide being added to their drinking water. As the study itself says: ‘It is unclear whether the product might have a similar effect in people.’
“As such, before we draw any conclusions about the impact on humans, more research is needed.”
She added: “It is encouraging that an inquiry into the impact of nano-materials on health is being carried out. The more we can learn about the way in which these ingredients impact our health, the more informed our choices will be.”
In light of the study’s findings, the French government has ordered an immediate investigation into the safety of titanium dioxide in food products, the results of which will be published in March.
A spokesperson for the Food Standards Agency told HuffPost UK: “As with all additives, titanium dioxide has undergone an extensive pre-market safety assessment which requires submission of a range of safety studies.
“Long-term studies have produced no evidence that titanium dioxide is carcinogenic. These have used higher doses and longer time frames than those used in the French study.
“Titanium dioxide was re-evaluated by the European Food Safety Authority (EFSA) last year and they considered its current use would not be of concern.
“EFSA will shortly be considering the French study which we understand contains a number of inconsistencies. The FSA is not advising people to avoid foods containing this colour.”