PhotoManufacturers of laundry soap sometimes add chemicals to produce a pleasant scent, but new research suggests this aroma could have some serious negative effects.

Researchers writing in the journal Air Quality, Atmosphere and Health say air vented from machines using the top-selling scented liquid laundry detergent and scented dryer sheet contains hazardous chemicals, including two that are classified as carcinogens.

“This is an interesting source of pollution because emissions from dryer vents are essentially unregulated and unmonitored,” said lead author Anne Steinemann, a University of Washington (UW) professor of civil and environmental engineering and of public affairs. “If they’re coming out of a smokestack or tail pipe, they’re regulated, but if they’re coming out of a dryer vent, they’re not.”

Steinemann is the same researcher who used chemical sleuthing to deduce what’s in fragranced consumer products. Her latest effort has focused on the air wafting from household laundry vents. Her findings build on earlier work that looked at what chemicals are released by laundry products, air fresheners, cleaners, lotions and other fragranced consumer products.

Manufacturers, it turns out, are not required to disclose the ingredients used in fragrances, or in laundry products.

The test

For the new study, researchers first purchased and pre-rinsed new, organic cotton towels. They asked two homeowners to volunteer their washers and dryers, cleaned the inside of the machines with vinegar, and ran full cycles using only water to eliminate as much residue as possible.

At the first home, they ran a regular laundry cycle and analyzed the vent fumes for three cases: once with no products, once with the leading brand of scented liquid laundry detergent, and finally with both the detergent and a leading brand of scented dryer sheets.

A canister placed inside the dryer vent opening captured the exhaust 15 minutes into each drying cycle. Researchers then repeated the procedure with a different washer and dryer at a second home.

Analysis of the captured gases found more than 25 volatile organic compounds, including seven hazardous air pollutants, coming out of the vents. Of those, two chemicals – acetaldehyde and benzene – are classified by the Environmental Protection Agency (EPA) as carcinogens, for which the agency has established no safe exposure level.

Can affect public health

“These products can affect not only personal health, but also public and environmental health. The chemicals can go into the air, down the drain and into water bodies,” Steinemann said.

The researchers estimate that in the Seattle area, where the study was conducted, acetaldehyde emissions from this brand of laundry detergent would be equivalent to three percent of the total acetaldehyde emissions coming from automobiles. Emissions from the top five brands, they estimate, would constitute about six percent of automobiles’ acetaldehyde emissions.

“We focus a lot of attention on how to reduce emissions of pollutants from automobiles,” Steinemann said. “And here’s one source of pollutants that could be reduced.”

It may come as no surprise, but Steinemann recommends using laundry products without any fragrance or scent.

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