Dust Is More Than Just Dirt

Can it: Household dust contains numerous chemicals that may be harmful, depending on your exposure. Stefan Wermuth/REUTERS

If you need another reason to bust out the vacuum cleaner, this might be it: The dust in your house is likely to harbor harmful chemicals that, if present at high enough levels, may damage your health.

Products we use every day—things like electrical appliances, hair shampoo and food packaging—contain chemicals that end up in the air we breathe. High exposure to chemicals like phenols and phthalates has been linked to asthma, cancer, hormone disruption, reproductive problems and developmental delays in children, among other complications. The chemicals eventually settle as dust on floors and other surfaces in our homes. Given that Americans spend more than 90 percent of their time indoors, there's a decent chance we may inhale these chemicals, absorb them through skin, or accidentally eat them (Mom was right to insist on hand washing before mealtimes).

"Most people think of dust as dirt, but it's more than that," says Ami Zota from George Washington University. She's the lead author of a new study on indoor dust, published September 14 in Environmental Science & Technology. "These chemicals pose potential threats, especially to children's health."

Researchers have known for a while now that household dust contains more than just dead skin, animal dander and dirt tracked in from outside. But the presence of consumer product chemicals in dust hadn't been comprehensively studied—until now. Zota's study marks the first time so many chemicals have been studied at the same time, and in so many places.

One type of chemical—phthalates—appears to pose the biggest risk; the study found it was present in the nearly 500 dust samples Zota and her team surveyed. Phthalates are added to plastics to make them softer and more flexible. They can be found in vinyl flooring, toys and even cosmetics. Their presence in dust is of concern because they have been linked to multiple health issues, such as disrupting hormones, and causing breathing difficulties and mental retardation in children.

In addition to phthalates, Zota and her colleagues identified four other chemical classes in the dust samples they surveyed—45 chemicals in total. Of these, 10 were present in 90 percent of the dust samples surveyed. These include fragrances, flame retardants (in furniture and electronics), phenols (in beauty products and reusable water bottles), and phthalates (in food packaging and vinyl flooring).

To obtain the data, Zota and her colleagues combed through 26 studies from the past 15 years. They analyzed dust samples collected from indoor environments such as homes, schools and offices from 14 U.S. states on the East and West Coasts. Only chemicals that were measured in three or more studies were included in the analysis.

While the ubiquity of toxic compounds present in household dust might sound alarming, the real issue of concern is how much of the stuff is actually entering our bodies. "The potential effect [of these chemicals] depends on our exposure to it," says Gediminas Mainelis, an environmental scientist from Rutgers University. "It depends on people's daily activities—are they walking in the dust or dancing in it?"

Young children are particularly vulnerable. "They're climbing around, crawling on the floor, putting their hands in their mouth," says Zota. They're also at a stage at which their brains and bodies are still developing.

So even though potentially harmful chemicals can almost always be found in household dust, it's how much you're exposed to them that really matters—something that can't be gleaned from this study. Yet, there are ways to minimize your exposure to these chemicals, says Zota. She and her co-authors suggest frequent hand washing, as well as regular dusting, mopping and vacuuming. Hard surface flooring, instead of carpets, can help keep a home dust-free too.

Federal health officials are also well aware of the risks associated with these chemicals. "There's a big change in the authorization of these chemicals," says Mainelis. Previously, chemical companies were free to put new products on the market without having to first demonstrate their safety. All that changed this June when Congress passed the Lautenberg Act, requiring safety testing for both new and existing chemicals.

Because so many products are already commercially available and testing all of them would be impossible, the Environmental Protection Agency is drawing up a priority list for its safety assessment. "One of the goals of our study was to help both regulators and scientists to identify chemicals to prioritize," Zota says, "for testing and for the development of safer alternatives."