Those dust particles accumulating on your bookshelf might seem like a minor annoyance, but they could be exposing you to potentially harmful chemicals, including flame retardants and phthalates. That's according to a new study in the journal Environmental Science and Technology.

Those chemicals and others in dust have been linked to serious illnesses such as asthma and cancer, as well as to hormonal changes and developmental and reproductive problems, the researchers say. The study was led by Ami R. Zota, Sc.D., at George Washington University in Washington, D.C. Young children are especially vulnerable because they’re more likely to come into contact with and ingest dust than adults. 

Zota and the other researchers reviewed information from indoor dust analysis studies published during or after 2000. They calculated concentrations of 45 chemicals found in samples collected across 14 states. Most came from people’s homes, but they also reviewed data on dust found in day-care centers, gymnasiums, schools, and people’s cars.

They estimated how much of each chemical, on average, actually gets into the body through breathing or swallowing, or through the skin.

“These estimates show that these chemicals do not stay in dust; rather, they get into bodies,” says Robin Dodson, Sc.D., a research scientist at Silent Spring Institute in Newton, Mass., and a co-author of the study.

To keep dust levels in your home low, Dodson says, you should vacuum regularly. A good air purifier might help, too. (Our buying guides to the  best vacuums and best air purifiers can help you find good ones.)

The team found that phthalates, a class of chemicals commonly used to soften plastic, represented the highest concentrations in dust particles and were among the highest in terms of exposure to children. The chemical is widely found in plastics used in food packaging, personal care products, and vinyl flooring.

All the samples contained DEHP, one of the most potent phthalates, Dodson says. It has been linked to hormonal disruption and can have harmful effects on the parts of the body that direct biological development and reproduction.

Flame retardants were also among the top 10 chemicals found in dust particles. As with phthalates, they have been linked to hormonal disruptions, toxicity in reproductive and developmental systems, and cancer. 

“I had a suspicion that the phthalates were going to rise to the top,” Dodson says. “But the fact that flame retardants were almost equally as high was interesting.”

Flame retardants are generally used in baby products, furniture, and insulation to meet flammability standards. But some of those codes or standards may not be very effective. “There may be better ways to deal with some of those issues than dumping those chemicals into the products we bring home every day,” Dodson says.

Other chemicals the team found in lower concentrations include fluorinated chemicals (such as PFCs in nonstick pans), fragrances, and phenols (such as parabens in body lotions and BPA in plasticware).

For many of those chemicals, there is no known safe level of exposure. Only about five of the 45 chemicals the team studied have safety limits, Dodson says. For that reason, she and her team didn't estimate the risk associated with their calculated exposures. “Our aim was to look at indoor exposure to chemicals, using dust as a way to understand their loading in our homes,” she says. 

Dodson also notes that inhaling dust particles isn't the only way you can be exposed to these chemicals. Many products you come into contact with every day—body lotion, toothpaste, medication, even the food you eat—can significantly increase your exposure.

In fact, while the level of the phthalate DEHP in dust is high, about 90 percent of people’s exposure to it comes from heating or storing food in plastic storage containers. “Likely we’ve underestimated our true exposure for some of these chemicals,” Dodson says.

Aside from using a good vacuum, an excellent way to limit your contact with these chemicals in general is to identify products you want to avoid, she says. Silent Spring Institute has developed a free app that offers several hundred research-based tips for consumers.

You should also wipe down surfaces with a damp cloth or mop, and make sure to wash your hands frequently, especially before you eat. That's extra important for children, who tend to pick up dusty things from the ground or floor and pop them into their mouth.