There's more coming out of your dryer than dry clothing.

RODALE NEWS, EMMAUS, PA—Looking for natural home products to help keep your family and planet healthy? You can put a big, fat "X" over any scented laundry products on your shopping list. Turns out popular laundry detergent ingredients are major air pollutants and can threaten health.

A 2011 study from fragrance sleuth Anne Steinemann, PhD, (a Rodale.com advisor) shows that carcinogenic chemicals typically found in vehicle exhaust are being released from household dryer vents when consumers use popular scented laundry products. "This is an interesting source of pollution because emissions from dryer vents are essentially unregulated and unmonitored," says lead study author Steinemann, professor of civil and environmental engineering and public affairs at University of Washington. "If they're coming out of a smokestack or tailpipe, they're regulated, but if they're coming out of a dryer vent, they're not."

THE DETAILS: Since no one regulates what comes out of these vents that spew into yards and city streets, and since regulations don't require laundry product companies to label any ingredients, Steinemann and team decided to take matters into their own hands. To determine what happens to laundry detergent and dryer sheet chemicals—and how they might wind up affecting our health—researchers purchased chemical-free organic towels and washed them with various popular detergents in washing machines that had been cleaned out with nontoxic vinegar. Then, they popped them in the dryer, captured emissions from dryer vents, and analyzed them in the lab.

When scented laundry detergent and dryer sheets were used, researchers detected up to 24 VOCs, or volatile organic compounds, that can trigger breathing problems and headaches. Compared to the control group (laundry washed and dried using detergents or dryer sheets), the scented laundry product dryer loads emitted seven hazardous air pollutants, including benzene and acetaldehyde—two compounds the U.S. Environmental Protection Agency lists as carcinogens. (There's no safe exposure level for these air pollutants.) "These products can affect not only personal health, but also public and environmental health," says Steinemann. "The chemicals can go into the air, down the drain, and into water bodies."

Researchers conclude that in the study area of Seattle, toxic acetaldehyde emissions from the top-selling laundry detergent tested would be on par with 3 percent of acetaldehyde emissions from vehicle exhaust.

The study was published online in the journal Air Quality, Atmosphere and Health.