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In a 2010 ad, feminine-hygiene purveyor Summer’s Eve seemed to suggest that using its products will lead to getting a raise. The next year, the company sparked an outcry when a series of its commercials featured stereotypically black and Latina voices—the latter actually cried, “Ay-yai-yai!”

Douche-makers might be running out of ways to make American women want to irrigate their nether regions. By now, the science is clear that shooting scented water into your ladyparts doesn’t prevent or treat infections. In fact, it only promotes yeast or bacterial overgrowth because it disturbs the normal vaginal ecosystem. The practice has also been linked to infertility and a greater risk of STDs.

Fortunately, douching is in decline: In 2002, a third of women between the ages of 15 and 44 did it, but just one-fifth did so by 2013. But the practice is still common among some women—particularly African Americans and Hispanics. The reason seems, at least in part, to be cultural: As Julie Morse described in The Atlantic recently, douching has really, um, shot up in Mexico in recent years. Women told Morse they do it to prevent vaginal infections, for a "clean feeling," or simply because their mothers told them to do it and they never stopped.

Ami Zota, an assistant professor of environmental and occupational health at George Washington University, says that though some women are still motivated to douche in an attempt to relieve odor or irritation, there are also “societal factors ... pressure to conform to societal beauty norms. There can be an element of using certain products as a way to culturally assimilate.” And of course, “targeted ads of these products to African Americans” don’t help.

Zota and other researchers from George Washington University and the University of California San Francisco recently discovered yet another reason not to douche. In a study of 739 women published last week in the journal Environmental Health, they found that women who douched had urine with a much higher concentration of phthalates. Phthalates are industrial chemicals that can adversely impact human health by altering the action of hormones in the body. In the study, women who douched had a 52 percent higher urinary concentration of a metabolite of one particular kind of phthalate, diethyl phthalate. Zota suspects that’s because diethyl phthalate is found in fragrances, and many vaginal douches are perfumed.

It’s not just douches that might be dangerous, of course. Phthalates are also found in most scented personal grooming products, such as perfume, nail polish, or hair products. They’re in shower curtains, medical devices, and other plastic consumer goods. It’s not entirely clear why, but certain meats and dairy products contain high levels, too.

These chemicals work by disrupting reproductive and thyroid hormones. Phthalates seem to have the greatest effect in the womb, so they are most concerning for women of reproductive age. In animal studies, phthalates have been linked to birth defects, and they also may contribute to developmental problems among children who are exposed in utero.

California, Vermont, and Washington have banned phthalates from all children's products. The European Union banned six phthalates from toys in 1999, and Congress banned three permanently in 2008. However, a scientific review of consumer products last year called out phthalates in personal products as a continuing area of concern.

Zota and her colleagues also examined the effect of tampons, feminine sprays, powders, and feminine towelettes on urinary phthalates. Those products didn’t have as strong of a connection with phthalate concentration. But, she points out, “it doesn't mean that these other products aren't a source of chemical exposure.” She hopes she and others can further study how beauty products influence phthalate levels—and how those levels impact health.

“What are the consequences of this experiment that we're conducting on ourselves?” she asked.

It would be impossible to rid our lives of all things that contain potentially harmful chemicals. (Zota did tell me, however, that she tries to buy fragrance-free toiletries). But douching, having no real benefit, should be an easy one to eliminate.

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