June 12, 2008 -- Could your shower curtain be harming your health?
An environmental group claims in a new study of vinyl shower curtains that some of them may release into the air toxic chemicals which could cause asthma, eye irritation or even cancer.
"We have a clear-cut case that these products release elevated levels of harmful chemicals," said report co-author Mike Schade, PVC campaign coordinator for the Center for Health, Environment and Justice. "Our research builds on a growing body of evidence that shows that the government fails to protect us from the growing number of toxic chemicals in products."
But some health experts are paying scant attention to those behind the curtain study. And perhaps with good reason.
Skeptics pointed out what they call a glaring error in the study's methodology. The group tested a total of five shower curtains, of which only one shower curtain — not one brand; one curtain — was subjected to complete testing for chemicals in its composition, as well as those it released into the air — a phenomenon known as "off-gassing."
Further testing was not performed "to avoid potential instrument damage," according to the report.
The study found the one curtain which was tested for off-gassing may have released, over the course of the first few hours after it was opened, chemicals that could be toxic if swallowed or inhaled only in quantities thousands of times greater than those found.
Critics said that the testing was not verified by an independent lab and didn't account for real-world conditions such as temperature or humidity in a shower stall.
The study also included estimated results for some of the chemical amounts it reported, and most of the off-gassed chemicals found initially were not detectable after a few days.
In short, it is a piece of shower curtain research that some experts said just doesn't hold water.
"It's a great example of how quickly a sound bite can become dangerous and contagious," said ABC News medical contributor Dr. Marie Savard.
"The idea that people should be tossing out their shower curtains based on a study that more or less focuses on a single shower curtain is absurd. This is scare science at its best, or worst, depending on how you look at it."
Also sounding off against the study was the Consumer Product Safety Commission (CSPC), the agency charged with protecting the public from dangers in more than 15,000 types of consumer products under its jurisdiction.
"The CSPC never just discounts or discredits information," said CSPC spokesperson Julie Vallese. "If it is a topic that the agency should have an interest in, we are always willing to take a look at the science."
But in this case, she noted, "Our toxicological experts took a look at the report and have many, many concerns with the credibility of the science involved."
Vallese cited the methodology, as well as the peer review, which comprised a selection of experts she criticized as non-objective.
"As for the report overall — based on the sound science and information that the CSPC has — the claims that are being made on shower curtains are 'phantasmagorical,'" Vallese said, adding that she doesn't get to use such a word very often in her work as a spokesperson.
Schade stood behind the report, noting that his team found that the shower curtains released 108 different volatile organic compounds, or VOCs. He maintained that many of these compounds have been linked with developmental problems in children, cancer and other health effects.
But he conceded that whether the levels of these VOCs emitted by the curtains could be directly linked to health effects was difficult to determine. "It's really hard to say that, because there are currently no standards for indoor air quality."
He cited that one class of chemicals — phthalates — were of particular concern due to their purported effects on babies in the womb.
"All five curtains we tested contained phthalates at pretty high concentrations," he said.
Phthalates, however, are present in nearly all flexible plastics. And the ubiquitous ingredient, unlike VOCs, is not released into the air by products containing it — suggesting that the primary way one would absorb it from their shower curtain would be through eating it.
Still, Shanna Swan, director of the Center for Reproductive Epidemiology at the University of Rochester School of Medicine and Dentistry, said that the idea that the researchers detected so many compounds warrants further study.
"I was surprised and alarmed by the large number of volatile organic compounds measured," she said. "I think it's a very strong message that we are exposed to mixtures of chemicals."
But she agreed that the findings, on their own, were far too weak to be considered a basis for an all-out ban on vinyl shower curtains.
"I don't think that this is a case for panic or immediately ripping these things out of houses," she said. "I don't think any regulations would be made on a single study."
And other epidemiologists cited the need for evidence of real-world effects in any study.
"I would think that they would have data showing how health outcomes have changed [due to exposure to shower curtains]," said Dr. Tim Byers, professor of epidemiology and community health at the University of Colorado School of Medicine. "That is always the question; is this a laboratory phenomenon that is not related to 'in use' conditions?"
Vallese said that unless a stronger link can be proven, consumers can probably put their minds at ease the next time they purchase a new shower curtain.
"In our busy lives, there are so many things that people should be or could be focused on to improve their health and safety," Vallese said. "Their shower curtains are not one of them.
"I think there are a lot of people out there sounding the false alarm."