Public Exposure

In 2010, the President’s Panel on Cancer reported that, in the course of their lives, about 41 percent of Americans will be diagnosed with cancer and 21 percent will die of the disease. And, making a connection between cancer and the wide distribution of potential carcinogens in the environment, the panel added that only a few hundred of the more than 80,000 chemicals on the market have been tested for safety.


February 13, 2015

Terra-Environment-without

“Except for the original blueprint of our chromosomes, all the material that is us — from bone to blood to breast tissue — has come to us from the environment.” — Sandra Steingraber,  Living Downstream: An Ecologist’s Personal Investigation of Cancer and the Environment

In 2010, the President’s Panel on Cancer reported that, in the course of their lives, about 41 percent of Americans will be diagnosed with cancer and 21 percent will die of the disease. And, making a connection between cancer and the wide distribution of potential carcinogens in the environment, the panel added that only a few hundred of the more than 80,000 chemicals on the market have been tested for safety.

Oregon State researchers are cutting into that knowledge deficit. Using robotic systems and rapid assessment in zebrafish, they have assessed the toxicity of more than 5,000 compounds in the U.S. Environmental Protection Agency’s ToxCast (a chemical evaluation program) and National Toxicology Program. Another 100,000 chemicals and nanomaterials — synthetic particles about 100,000 times smaller than the width of a human hair — have been evaluated as well. With partners at the Pacific Northwest National Laboratory, they are comparing zebrafish assays with data from mouse models, cell cultures and other testing methods.

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Exposure to potentially harmful chemicals is commonplace. And pesticides and industrial pollutants aren’t the only sources. Wood smoke, leafy green vegetables and grilled steak contain PAHs (polycyclic aromatic hydrocarbons), some of which are known to cause cancer in laboratory animals.

The goal is to identify the “really bad actors,” says Joe Beckman, director of the Environmental Health Sciences Center at Oregon State. “This could change the way we do public health.”

New knowledge is also emerging from Oregon State’s program in radioecology, the study of radioactivity in the environment. And researchers are beginning to tackle what some experts consider the most serious public health threat of the future: climate change.

Exposure to Impact

If you live near a chemical plant or by a freeway, there’s more than fresh air in the breezes that waft across your yard, through open windows and under doors. The wind carries volatile compounds used in manufacturing and byproducts of fossil fuel combustion as well.

Across the country, people are exposed to airborne chemicals from an array of sources — gasoline and diesel engines, natural-gas wells, heating furnaces, pesticide applications and factories. In the hills of Appalachia, the concrete canyons of Manhattan and the tree-lined streets of Corvallis and Eugene — and as far away as West Africa and Peru — people are monitoring the air they breathe with the help of scientists at Oregon State University.

Researchers in Oregon State’s Environmental Health Sciences Center have developed a sampling approach that tracks chemicals with extreme sensitivity. In a lab led by Kim Anderson, professor of Environmental and Molecular Toxicology, scientists specialize in what are called “passive samplers.” Over the last two decades, Anderson’s group has deployed more than 19,000 such monitors that collect chemicals in air and water for measurement in her lab.

In 2004, this technology — which works silently without fans or other motorized components — helped to allay fears of a public health threat. Data collected by Anderson’s team in the Willamette River near Newburg demonstrated that contaminants such as pesticides were not responsible for fish deformities that had raised alarms. The cause turned out to be an infectious parasite.

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In 2010, immediately after the Deepwater Horizon oil disaster in the Gulf of Mexico, Anderson’s lab deployed air samplers in four coastal states. Results revealed the presence of petroleum compounds, including some not typically monitored by the U.S. Environmental Protection Agency. Further testing at Oregon State’s zebrafish lab showed that these chemicals can affect embryonic development.

Today, silicone wristbands and vented metal boxes are among the Anderson lab’s sampling platforms. They capture more than 1,400 of the many thousands of chemicals that may be present in our homes, neighborhoods and workplaces.

Scientists even have a name for the accumulation of chemicals, both natural and synthetic, and other factors that affect health: the “exposome.” Coined in 2005 by Dr. Christopher Wild, director of the International Agency for Research on Cancer, the exposome shapes us from Day One. In the womb, drugs and pollutants can affect development. As we age, interactions with environmental chemicals, UV radiation and microbes continue to unfold, sometimes leading to diseases, such as cancer and diabetes, that can take decades to emerge.

“There are a lot of exposures we don’t have a grip on,” says Anderson. “We don’t have a lot of data. A contaminant may or may not be bioavailable. It has to cross some sort of biological threshold in order to have an effect on an organism.”

Following the Chemical Trail

Linking environmental exposure to human health is tricky business. It starts with knowing the myriad chemicals we encounter every day in personal care products, household furnishings, medications, food, water and air. By monitoring for many chemicals at one time, Anderson and her team are beginning to define part of the exposome for individuals and for communities.

But that’s only the first step along the trail from exposure to health. Once they extract the chemicals from a sampling device, researchers identify each compound in a mass spectrometer. This machine separates molecules first by ionizing them in an electric field and then by passing them through a magnetic field where they spread out like runners in a long-distance race.

Next, the scientists need to know if the chemicals are bioactive … that is, can they affect cells and disrupt the body’s networks. So researchers may send sample extracts to Oregon State’s highly automated zebrafish lab, in which the effect of chemicals — or their lack of effect — on developing embryos can be determined within days. Or they might walk samples next door to the Linus Pauling Institute where scientists run them through the Ames test, a common method for seeing if chemicals cause mutations in DNA.

In either case, small amounts of chemicals can reveal large clues about the potential for a biological impact. That surprises Joe Beckman, the director of OSU’s Environmental Health Sciences Center. “The miniaturization that’s possible with these tests is really important because the wristbands really don’t pick up that much material,” he says. “There’s not that much surface area. To me it’s astonishing that they pick up as much as they do.”

Anderson explains that the samplers mimic the most basic part of living organisms: the cell. “Passive sampling is a surrogate for a cell,” she says. “It’s very lipophilic (attractive to organic compounds such as proteins and lipids), like your cells are. And it has pores within the polymers. There are different types of polymers, carbon or silicone, that mimic a cell. The key to any of the polymers we use is the chemistry.”

Silicone wristbands can adsorb chemical pollutants. (Photo: Stephen Ward)
Silicone wristbands can adsorb chemical pollutants. (Photo: Stephen Ward)

In a study to test methods for using wristbands, Anderson’s team — including Steven O’Connell, a former graduate student; and Laurel Kincl, assistant professor in the College of Public Health and Human Sciences — asked eight roofers who work with hot asphalt materials to wear them on the job. While some wristbands were worn for a single eight-hour shift and others for a 40-hour work week, petroleum-based compounds were recovered from all of the devices. Among the chemicals were 12 PAHs on the U.S. Environmental Protection Agency’s list of priority pollutants. The researchers published their results in Environmental Science and Technology, a professional journal.

Citizen Science

Anderson sees such monitoring efforts as a way to engage non-scientists in research. “Everybody loves to know more about their environment,” she says. As a girl, she was inspired by her grandfather who had a fourth-grade education but read every National Geographic, educating himself. “He was so excited when I got my geology degree. He wanted to know more about his environment. He isn’t unique. There are lots of people like that,” she adds.

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Almost 500 people have signed up with Anderson’s lab to receive updates on opportunities to participate in monitoring projects. Additional requests have come from small businesses (gas stations) and government agencies (the Department of Defense).

In New York City, researchers at Columbia University are using wristbands from Anderson’s lab to monitor chemical exposure among pregnant women in low-income areas of the city. “The silicone wristbands offer a huge advance over what we’ve been able to do,” says Julie Herbstman, one of the investigators on the project.

Since 1998, researchers have monitored chemical exposure by asking women to wear small backpacks equipped with air filters attached to battery-powered pumps. Because of the continuous hum and weight (5 pounds), researchers limited exposure time to 48 hours. In contrast, the wristbands are unobtrusive, and people can wear them 24/7 for longer periods of time.

In Ohio, Anderson’s team is working with the University of Cincinnati College of Medicine and Carroll (County) Concerned Citizens to monitor air quality around natural-gas wells. Vented sampling boxes have been stationed around the wells, and homeowners are wearing wristbands to track personal exposure.

In West Eugene, OSU is working with a community group, Beyond Toxics. Passive samplers and spirometers (devices that measure the force of a person’s breath) could provide an effective way to measure exposure and breathing difficulties such as asthma. Poor air quality has been well-documented in low-income neighborhoods and schools near highways, railroad switching yards and factories.

Funding for these and other projects comes from a variety of sources: the National Institute of Environmental Health Sciences, the U.S. Environmental Protection Agency and even the Food and Agricultural Organization of the United Nations. The goal in all cases is to “strengthen the influence of science on decision-making,” says Anderson. “We have lots of questions but not much data. I like to bring numbers and facts to the table.”

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