Scented products contain undisclosed compounds that are defined as hazardous chemicals under U.S. law, an environmental researcher says.

The finding suggests there is a need for better disclosure of such ingredients, because "the public may have inadequate information about potential exposure risks, or perhaps a false sense of assurance that they do have such information," Anne Steinemann, from the University of Washington, writes in a recent study.

"We rely on product information (such as labels) and product regulations to reduce potential risks," says her article says, published online in the Environmental Impact Assessment Review in July.

10 toxic or hazardous compounds

Steinemann's analysis of six best-selling items (three air fresheners and three laundry products) found they contained nearly 100 volatile organic compounds, or VOCs, "but none of the VOCs were listed on any product label."

Ten of the VOCs are regulated as toxic or hazardous under U.S. laws, of which three are classified as hazardous air pollutants.

"In particular, fragrance compounds, used in a wide variety of consumer products, can be primary sources of human exposure to VOCs," the study finds.

The evidence is conflicting on the link between indoor VOCs and health problems.

A British Columbia government website cautions that indoor VOCs can cause eye, nose and throat irritation, headache, nausea, dizziness and skin problems, and in higher concentrations may damage the liver, kidney or central nervous system. According to the site, some VOCs are suspected to cause cancer, though exact health effects depend on the level and length of exposure.

But other studies, including British research, suggest there is little to no evidence supporting such contentions. "No evidence suggests that current U.K. indoor domestic exposures to VOCs, either individually or as a total, pose a health risk," Steinemann writes in a review of other research.

Steinemann, who measured concentrations of the chemicals, pointed out that exposures are different from concentrations. Moreover, she measured only primary pollutants, not secondary ones (those caused when chemicals mix with other chemicals), and did not determine whether the VOC levels found would trigger legal problems.