Vaginal powders and douches may contain chemicals linked to cancer, research suggests.
Experts have urged women to avoid feminine hygiene products for years.
Often highly fragranced, the products may throw the vagina’s delicate pH off balance, leaving women at risk of thrush or even ovarian tumours.
Despite the warnings, the high street is awash with washes and powders that help keep you fresh “down there”.
To learn more about the dangers, scientists from the University of Michigan asked more than 2,400 women how often they use these products.
They found using feminine hygiene aids just twice a month raised levels of cancer-causing chemicals in the women’s blood by up to 81%.
Here, “cancer-causing chemicals” refers to substances called volatile organic compounds (VOCs), which are found in everything from perfume and nail varnish to moth repellents and paint.
VOCs have been linked to cancer, as well as “menstrual disturbances”, miscarriages and birth defects, the scientists wrote in the Journal of Women’s Health.
The chemicals are known to enter the body via the skin, lungs and digestion, however, less was known about absorption through the vagina.
To learn more, the scientists looked at 2,432 women, aged 20-to-49, who took part in the National Health and Nutrition Examination Survey between 2001 and 2004.
The women were asked how often they used vaginal douches, sprays, powders and wipes, as well as tampons and sanitary towels.
Blood samples showed those who douched as little as once a month had 18% more of the chemical 1,4-dichlorobenzene (1,4-DCB) in their blood. This is compared to the women who never douched.
And douching twice a month or more raised levels of 1,4-DCB by 81%.
Animal studies have linked 1,4-DCB to reproductive defects, as well as lower birth weight and a higher risk of death among newborns.
The results also found the women who used vaginal powders in the past month had 36% more of the VOC ethylbenzene in their bloodstream.
Short-term exposure to ethylbenzene is linked to dizziness, eye irritation and a tight chest, according to the United States Environmental Protection Agency (EPA).
A study by the National Toxicology Program found rodents who inhaled the VOC were more at risk of kidney, liver and testicular tumours.
There is, however, “limited information” on the chemical’s cancer risk in humans, the EPA adds.
The Michigan study found no link between the use of tampons or sanitary towels and higher VOC levels.
This may be due to sanitary products typically only being used for a few days a month, rather than being regularly reapplied, like vaginal powders, the scientists claim.
“Based on the findings of this study, feminine hygiene products that expose the vulvovaginal tissue to harmful VOCs should be avoided”, Dr Susan Kornstein, the journal’s editor-in-chief, said.
Both 1,4-DCB and ethylbenzene are added to personal-care products to retain a fragrance’s scent, they wrote.
Fragrances may also be a source of VOCs themselves, with cosmetic manufacturers rarely being required to disclose the ingredients within a perfume on a product’s label, they added.
This is not the first time the dangers of intimate hygiene products has been raised.
Vaginal douching removes natural secretions the vagina releases to keep it healthy.
Losing these secretions affects its pH, raising the risk of infections.
There are also concerns douching could release chemicals called phthalates into the reproductive tract.
These disrupt hormone production and could increase the risk of ovarian cancer.
“I can't think of any circumstances where douches are helpful,” Professor Ronnie Lamont, spokesperson for the Royal College of Obstetricians and Gynaecologists, told NHS Choices.
Applying powders to the intimate area has proven to be even more controversial.
A law case made international headlines when 22 women were awarded a record $4.7 billion (£4.19 billion) in damages after a jury found Johnson & Johnson talcum powder caused them to develop ovarian cancer.
The products were found to have asbestos intermingled among the mineral talc, both of which were in many of the women’s ovarian tissue.
In its natural form, some talc contains asbestos, which is known to cause cancers in and around the lungs when inhaled, according to the American Cancer Society.
When it comes to other forms of the disease, studies have thrown up mixed results.
Some suggest a slightly increased risk of ovarian cancer in those who use talcum powder, while others found no risk.
Nonetheless, the International Agency for Research on Cancer - part of the World Health Organization - classes talc that contains asbestos as “carcinogenic to humans”.