Elena Rios still remembers going into the bathroom as a child and smelling a pungent odor from the big, round air freshener hanging on the back of the toilet.

“I’m Mexican-American, I grew up in Los Angeles, and I can tell you that particular product was in all the stores in the neighborhood, at low cost,” said Rios, a doctor who currently heads the National Hispanic Medical Association.

Now a new study concludes that heavy use of these products could be jeopardizing the health of consumers, particularly Hispanics, across the country.

Among residents tested in parts of Houston, Los Angeles, and Elizabeth, N.J., Hispanics faced a cancer risk from air pollutants as much as five times the rate of non-Hispanic whites. But it wasn’t outdoor air causing the greatest risk; it was something much closer to home: A chemical, called p-dichlorobenzene, found in many inexpensive toilet deodorizers and moth repellents in bathrooms and closets.

Inside Houston homes with the highest levels of the chemical, 16 out of every 1,000 Hispanic residents were at risk of cancer. In the New Jersey city, six out of every 1,000 were at risk, and in Los Angeles, four out of every 1,000.

Experts say such a high cancer danger from a single source is highly unusual. Federal guidelines usually consider ten cancers per million people an “acceptable” risk; in some of the Hispanic households, the cancer risk is about 1,000-fold higher.

“The risk numbers we’re talking about for that group are comparable to or greater than what we see for radon, which has been identified as the most dangerous hazard in homes in the country by far,” said Richard Corsi, a professor specializing in indoor air pollution at the University of Texas at Austin. He was one of the authors of the study, which was published online in the journal Environmental Health Perspectives last month.

Many of the products contain 100 percent p-dichlorobenzene packaged in large, white tablets or blocks that can be hung inside the back of toilets or placed in men’s urinals. The chemical also is used in some mothballs, and in moth-repellent crystals packaged in miniature hangers. The products are designed to release the substance into the air in confined spaces, meaning it sticks to clothes and skin and is repeatedly inhaled.

Corsi and the other authors said their findings were alarming, particularly because Hispanics are the fastest growing population in the United States. “Hispanic” was a designation researchers assigned to people who spoke Spanish as their first language and those who identified themselves as Hispanic.

The researchers are not sure why Hispanics had sharply higher exposure. But they noted that the products cost less than other deodorizers, and that they may have been more readily available in countries from which they emigrated.

Rios, from the Hispanic medical association in Washington, D.C., said marketers have targeted generations of Latino Americans with the cheap air fresheners.

“It’s because of the stores in the neighborhood, and the buying patterns for low income neighborhoods, where you have limited opportunities for purchasing products,” she said.

Other populations, such as people in colder climates who keep windows closed or use more mothballs in coat closets, also might be at higher risk. Some mothballs contain p-dichlorobenzene while others are made of another chemical, naphthalene.

“Basically if Caucasians were using more of these products, I would expect their exposures and risks would be just as high,” Corsi said.

The authors cautioned that the study was based on only a couple hundred volunteers, which is not statistically representative of the country. But they, along with researchers not involved with the study, said the findings are important because they were so striking.

"These are just three locations in three parts of the country," said Tracey Woodruff, associate director of reproductive health and the environment at University of California, San Francisco. "Nonetheless, they have actual monitoring data, which to me is very powerful.”
The air pollutants measured in the homes are “at a level that would be of concern. High concern,” said Woodruff, who specializes in research of hazardous air pollutants.

The authors of the new report recommended that products containing p-dichlorobenzene be removed from homes. There are plenty of other air fresheners available, they said, although they cost more.

“There’s a very simple answer…don’t let people purchase these products anymore,” said Corsi. “It doesn’t take a sophisticated air pollution control system to solve this problem.”

But regulating the products isn’t simple: They come under the authority of various federal and state agencies. 

Air fresheners are regulated by the Consumer Products Safety Commission. Officials from the commission did not return calls seeking comment about the products.

The U.S. Environmental Protection Agency regulates moth repellants because they are considered pesticides. The agency has approved use of the chemical, although it requires the products to bear warnings such as "avoid breathing vapors" because they can irritate eyes and nasal passages and cause liver problems.

Regulators from various agencies disagree about the level of human threat that these products pose. In animal tests, p-dichlorobenzene causes kidney and liver tumors.

The EPA and the Department of Health and Human Services decided years ago that p-dichlorobenzene was a hazardous air pollutant and possible human carcinogen. As a result, the EPA regulates its industrial emissions. But the arm of EPA that approves pesticides concluded in 2007 that it was “not likely to be carcinogenic to humans.” A full assessment is now being conducted, an agency spokeswoman said.

Maria Morandi
, the study’s principal investigator, explained that p-dichlorobenzene is a milder carcinogen than other substances, meaning it could take years of high-level exposure to develop cancer. The EPA only looked at low levels of exposure from the products, while the new data show some Hispanics are breathing extremely high levels, said Morandi, a recently retired University of Texas at Houston assistant professor of environmental sciences and occupational health.

California has banned bathroom products containing p-dichlorobenzene since 2006. The city of Seattle, New York State’s corrections department, and New York City’s fire department also have banned them. Urinal blocks traditionally have been used in some prisons and firehouses.

“It’s nasty stuff,” said Dmitri Stanich, a spokesman for the California Air Resources Board, which regulates air pollutants. “We banned it as an air freshener because it’s carcinogenic. Our position is it’s not safe.”

However, mothballs and miniature hangers loaded with the substance are still on sale in California because they come under the control of a separate state agency.

The California Department of Pesticide Regulation this year began to assess the potential hazards of the moth products. “We are evaluating whether additional restrictions are necessary,” said Mary-Ann Warmerdam, the department’s director.

Willert Home Products, a leading manufacturer of home air freshener and closet products, said during California’s rulemaking that the levels people were exposed to were too low to cause harm, and that there was no evidence of human cancer. Calls to the company seeking comment on the new study were not returned.

In the study, 243 people wore personal monitors that measured their exposure to 12 major pollutants over 48-hour stretches. The results were based not on actual cancers, but on measured levels of the chemical, which were then used to calculate the estimated cancer risk. A larger study is being conducted.

Hispanic residents in Elizabeth and Houston had higher exposures than those in Los Angeles, probably because there were also greater exchanges of indoor and outdoor air in California. In the Los Angeles area, risk levels from the chemical were about equal for all populations, but still higher than federally accepted guidelines. The testing was done from 1999 to 2002, years before California’s partial ban was enacted.

Hispanics in the study also were exposed to higher levels of formaldehyde, probably from car upholstery and particle board used in some home construction.

And Latina women had higher exposure to chloroform, probably as a byproduct of cleaning with chlorine. But by far the highest levels of exposure were from p-dichlorobenzene.

The researchers said their findings show that consumers should be wary of household chemicals because the risk of inhaling them can be more dangerous than breathing the polluted air outside.

Rios said she was glad that scientists were studying Hispanics’ exposure to chemicals in consumer products. “Nobody realized the dangers about pesticides and migrant workers for a long time either,” she said.

This article originally ran at Environmental Health News, a news source published by Environmental Health Sciences, a nonprofit media company.