From the Outside In

The dose may make the poison, but a new study finds even low levels of certain toxins might affect our health.

Julie KerteszPhoto: Julie Kertesz

Whether you spend your time binge-watching Netflix, maxing out your Crossfit routine, or somewhere in between, we all come into contact with small quantities of certain toxins in the air we breathe. Chemicals like benzene, toluene, ethylbenzene, and xylene are just about everywhere—and according to a new study, exposures to them in low doses might be disrupting our hormonal systems.

Researchers from the Endocrine Disruption Exchange and the University of Colorado, Boulder reviewed 40 studies on those four chemicals, which are found at oil and gas wells and within everyday products such as gasoline, glues, detergents, dyes, and pesticides. Large doses of these substances can cause reproductive problems and cancer, but the U.S. Environmental Protection Agency says they won’t harm us in smaller amounts. Not so, say the paper’s authors. They found that exposure levels lower than the EPA’s threshold could be linked to health issues like asthma, heart disease, and low birth weight.

The findings are cause for concern, says lead author Ashley Bolden, a research associate at the Endocrine Disruption Exchange.

The biggest danger, the report suggests, comes from exposure indoors, where Americans on average spend more than 80 percent of their time. Pollution can blow into homes through open windows, come in on dust from shoes, or off gas from toys and other products. The four chemicals studied are present in 90 percent of air samples, yet you’d never know it because they are odorless at low doses. Ethylbenzene, for example, is one of the top 10 chemicals used in kids’ toys and on playgrounds, where, according to the EPA, it can waft into the air or get onto little sneakers.

The review is important because the effects of low-level exposure to pollutants—especially these four—haven’t received much attention, says Ruthann Rudel, a toxicologist with the Silent Spring Institute, which studies environmental links to breast cancer. A spokesperson for the EPA told Environmental Health News that the agency would review Bolden’s paper and possibly incorporate some of its findings into its own work. With enough data, the agency could ban the chemicals from certain products or limit how much is allowed, depending on factors such as the likelihood to cause cancer or exacerbate other health issues.

Until we know more about what we’re inviting in from outside, Bolden suggests making sure our buildings are well ventilated—a simple enough precaution, and hopefully in this case, too, a little will go a long way.

onEarth provides reporting and analysis about environmental science, policy, and culture. All opinions expressed are those of the authors and do not necessarily reflect the policies or positions of NRDC. Learn more or follow us on Facebook and Twitter.

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