Vaginal douching may not have the health benefits some believe, but you'd think the practice would at least be safe. Douching products are prominently displayed in the feminine care aisle of the drug store; you don’t even need a prescription.

But a new study has found that using vaginal douches exposes a woman to high levels of dangerous chemicals called phthalates.

Phthalates are a group of chemicals used to make plastics more flexible and harder to break. They are added to polyvinyl chloride plastics to make products such as plastic packaging film and sheets, garden hoses, inflatable toys, blood-storage containers, medical tubing, and some children's toys. They are also in hundreds of other products, from vinyl flooring, adhesives, and detergents, to automotive plastics, plastic clothes (raincoats), and personal-care products like soap, shampoos, hair sprays, and nail polishes.

Women who douched two or more times per month had a 152.2 percent higher MEP concentration compared to non-users of vaginal douches.

Little mention of the prevalence of these harmful chemicals in feminine care products can be found in the scientific literature, researcher Ami Zota, told The Doctor. “Before our study, only a few scientists and clinicians were aware that feminine care products contained harmful chemicals, including phthalates.”

Researchers at The George Washington University and the University of California San Francisco examined data from 739 women between the ages of 20 and 49 years old who answered questions about their use of feminine hygiene products as part of the National Health and Nutrition Examination Survey (NHANES).

The researchers looked at the association between the self-reported use of feminine hygiene products such as tampons, sanitary napkins, and douches, and levels of monoethyl phthalate (MEP) and mono-n-butyl phthalate (MnEP) in women's urine.

They found that douching within the past month was associated with higher levels of MEP in the urine, but not MnEP. In addition, women who douched two or more times per month had a 152.2 percent higher MEP concentration compared to non-users of vaginal douches. Use of other feminine hygiene products was not associated with higher urine levels of MEP or MnEP, however.

“Feminine care products often contain industrial chemicals women may not be aware of that may impact their personal and reproductive health,” Lisette Davidson, a clinician with the department of obstetrics and gynecology at Kaiser Permanente, told TheDoctor. Women need to know what they are using on their bodies and the chemicals in those products, Davidson believes.

Both the U.S. Department of Health and Human Services and the American College of Obstetrics and Gynecology recommend against douching. According to Davidson, “Douching can increase the risk of infection, and has potential implications for reproductive health as well.”

The vagina is basically self cleaning because it has a high turnover of cells, she explained. Women can clean the external vagina with regular showering and washing.

The study is published in the journal Environmental Health.