The chemicals in question, dichlorophenols, or DCPs, are EPA-classified "hazardous pollutants," and some are known carcinogens. One study conducted by the American College of Allergy, Asthma and Immunology has found that people with high levels of these chemicals are more likely to suffer from food allergies to milk, eggs, peanuts, and shrimp.
The authors of the new study, published in the February 2014 Environmental Health Perspectives, used urinary concentrations of DCPs collected by the CDC as a part of its biannual National Health and Nutrition Examination Survey; the survey monitors levels of hundreds of chemicals in a sampling of Americans' blood and urine.
Levels of DCP chemicals were detected in 81 percent of the sample, with high-income participants having the lowest levels. Low-income participants had the highest levels, which the authors attributed to the use of DCPs in cheap cleaners and cheap household pesticides. They also saw an association between housing type and DCP levels—people who lived in apartments or other forms of multiunit housing were 1.5 times more likely to have DCP levels in the top 5 percent than people who lived in single-family homes. That last factor suggests that people who live in close quarters are going to suffer the indoor-air-quality problems of their neighbors, even if they don't use products containing these chemicals in their own homes.
The new study didn't attempt to finger exact exposure sources for DCPs, but these chemicals are breakdown products of chemicals called dichlorobenzenes, the most common source of which is mothballs. You might also encounter them in room or closet air fresheners and in cheap toilet-bowl deodorizers, such as the style you hang over the side of a toilet bowl. However, DCPs are also by-products of the chlorination process, and one, 2,4-DCP, is used to manufacture 2,4-D, the most commonly used weedkiller used on U.S. lawns and gardens.
The fact that 81 percent of the population sampled in this study harbors residues of these harmful chemicals "is alarming," says Alexandra Scranton, director of science and research at the nonprofit Women's Voices for the Earth, which advocates for greener cleaning products and toxic-chemical-reform policies. DCPs evaporate easily from solid products and become airborne gases that can travel from apartment to apartment (or dorm to dorm, condo to condo…) really easily. "Even if you're not using them, you're likely to be exposed."
Being unable to control your exposure to such toxic chemicals is unsettling, but here are some steps you can take to protect yourself:
• Opt for nontoxic moth control. Vacuum your closets before storing winter woolens and stow the clothes in plastic boxes or vacuum-sealed bags to prevent an infestation.
• Deodorize your toilet naturally. Leave the "cherry fresh scent" bomb hanging in the cleaners aisle, and do this to both clean and de-stink your commode: Dump half a bottle of white vinegar into the toilet, shut the lid, let it sit overnight, and then scrub and flush in the morning.
• Weather-strip your doors. If you live in an apartment or multiunit dwelling, put some weatherstripping around your doorframe and attach a draft guard to the bottom—both are relatively inexpensive and available at any hardware store. Doing so will reduce the amount of air that wafts into your home from your neighbors'.
• Buy a water filter. The water filters certified to remove dichlorobenzene and its DCP breakdown products are expensive and difficult to install, but a standard carbon pitcher-style water filter will remove chlorine and thus any chlorine breakdown products like DCPs that may evaporate into your indoor air.