The McCormick and Baxter Superfund Site is located on the Willamette River in Portland, Oregon and has PAH contaminated soils and sediments from historical creosote operations. As part of an Oregon Department of Environmental Quality (ODEQ) ten year study to assess the effectiveness of the sediment cap, passive sampling devices from Kim Anderson’s lab were deployed by U.S. EPA Region 10 divers in both sediment and water at the site. Included in this study was a newly designed passive sampling sediment probe which allowed for deployment in the rocky armoring of the sediment cap. Based on data from this study, the ODEQ reported that the sediment cap appears to be effective in meeting its remedial objectives. The full results of the study, used to inform ODEQ regulatory decision making, is available here (https://semspub.epa.gov/work/10/100031136.pdf), beginning on page 20.
CORVALLIS, Ore. – Air pollution controls installed at an Oregon coal-fired power plant to curb mercury emissions are unexpectedly reducing another class of harmful emissions as well, an Oregon State University study has found.
Portland General Electric added emission control systems at its generating plant in Boardman, Oregon, in 2011 to capture and remove mercury from the exhaust.
Before-and-after measurements by a team of OSU scientists found that concentrations of two major groups of air pollutants went down by 40 and 72 percent, respectively, after the plant was upgraded. The study was published in the journal Environmental Science & Technology this month.
The Boardman plant, on the Oregon side of the Columbia River about 165 miles east of Portland, has historically been a major regional source of air pollution, said Staci Simonich, environmental chemist in OSU’s College of Agricultural Sciences and leader of the study team (OSU SRP Project 5).
“PGE put control measures in to reduce mercury emissions, and as a side benefit, these other pollutants were also reduced,” she said.
The pollutants in question are from a family of chemicals called polycyclic aromatic hydrocarbons (PAHs), which are formed from incomplete combustion of fossil fuels and organic matter. PAHs are a health concern because some are toxic, and some trigger cell mutations that lead to cancer and other ailments.
Simonich and her team tracked concentrations of airborne PAHs during 2010 and 2011 at Cabbage Hill, Oregon (elevation 3,130 feet), about 60 miles east of the Boardman plant, and also at the 9,065-foot summit of Mount Bachelor 200 miles to the southwest.
They sampled approximately weekly from March through October of 2010, and again from March through September of 2011. They analyzed the samples for three major groups of PAHs: the parent chemicals and two “derivatives”— groups of PAH chemicals resulting from the decomposition of the parent PAHs.
The 2011 measurements at Cabbage Hill showed significantly reduced concentrations of the parent PAHs and also of one of the derivative groups, called oxy-PAHs (OPAHs). The other derivative group, called nitro-PAHs (NPAHs), did not show significant reduction. The NPAHs were more likely to have come from diesel exhaust associated with Interstate Highway 84, Simonich said.
Some of the individual PAH chemicals were reduced so much after the upgrade that the researchers couldn’t tell from the data whether the plant was running or not, she added.
“The upgrades reduced the PAH emissions to the point where we could hardly distinguish between air we sampled along the Gorge and at the top of Mount Bachelor.” While Oregon’s mountaintops typically have less air pollution than lower-lying areas, Simonich’s previous work has shown that they are not pristine.
She and her student Scott Lafontaine stumbled upon the Boardman findings while studying PAHs that originate in Asia and ride high-level air currents across the Pacific Ocean. They were measuring how much of each PAH type was coming from Asia, and how much from within the Northwest or elsewhere.
“We wanted to see if there was the same level of trans-Pacific transport at lower elevations—where people actually live—as we’ve previously found at Mount Bachelor,” Simonich said.
When the researchers analyzed the Cabbage Hill data for 2010, they found high levels of the chemicals they were studying, but the pollutants did not have an Asian signature.
Then in 2011, they found that the Cabbage Hill concentrations of the parent PAHs and OPAHs were much lower than they’d been in 2010.
“We looked at the data and said, ‘Wow! 2010 is different from 2011, and why should that be?’” Simonich said. “We had trouble understanding it from a trans-Pacific standpoint. So we started thinking about regional sources, and that’s what led us to look at emissions from Boardman.”
They got in touch with officials at PGE and learned about the April 2011 upgrade. Their review of PGE’s emission records revealed correlations with their own measurements. They concluded that the reductions in PAH concentrations at the Cabbage Hill site were caused by the 2011 upgrade.
The upgrade may also aid her research, Simonich said. “When you have a major point source of pollution nearby, it’s hard to pick out the signal of the Asian source coming from farther away. Now that these emissions are reduced, we may be able to pick up that signal much better.”
More important, she said, the air is cleaner.
“Boardman used to be a major source of PAH pollution in the Columbia River Gorge, and now it’s not,” she said. “That’s a good thing for PGE and a good thing for the people living in the Gorge.”
The study was funded by the OSU Superfund Research Program, a multidisciplinary center administered by the National Institute of Environmental Health Sciences. Pacific Northwest National Laboratory and the Confederated Tribes of the Umatilla Indian Reservation collaborated on the research.
Scott Lafontaine received his MS in Chemistry at OSU and is now pursing a Ph.D. in Food Science with Dr. Thomas Shellhammer in the Food Science Department.
I am focusing on brewing science and specifically on advancing the understanding of the chemical behavior of hop flavor and aroma in beer. I am very excited to have the opportunity to continue my graduate studies at OSU, within a program that has been analyzing hops since 1932. I look forward to using my unique background and education to bridge some of the concepts I learned while working on my master’s thesis. I want to be able to bring a new perspective to some of the key questions in this field.
– By Gail Wells, 541-737-1386, firstname.lastname@example.org, on Twitter @OregonStateExt
Source: Susan Tilton, 541-737-1740, email@example.com http://bit.ly/OSU_AgNews1542
CORVALLIS, Ore. – Scientists at Oregon State University have developed a faster, more accurate method to assess cancer risk from certain common environmental pollutants.
Researchers found that they could analyze the immediate genetic responses of the skin cells of exposed mice and apply statistical approaches to determine whether or not those cells would eventually become cancerous.
The study focused on an important class of pollutants known as polycyclic aromatic hydrocarbons, or PAHs, that commonly occur in the environment as mixtures such as diesel exhaust and cigarette smoke.
“After only 12 hours, we could predict the ability of certain PAH mixtures to cause cancer, rather than waiting 25 weeks for tumors to develop,” said Susan Tilton, an environmental toxicologist with OSU’s College of Agricultural Sciences.
For at least some PAH mixtures, the new method is not only quicker but produces more accurate cancer-risk assessments than are currently possible, she said.
“Our work was intended as a proof of concept,” said Tilton, who is also affiliated with the OSU’s multidisciplinary Superfund Research Program, a center funded by the National Institute of Environmental Health Sciences (NIEHS).
“The method needs to be tested with a larger group of chemicals and mixtures. But we now have a model that we can use to develop larger-scale screening tests with human cells in a laboratory dish.”
Such a method will be particularly useful for screening PAHs, a large class of pollutants that result from combustion of organic matter and fossil fuels. PAHs are widespread contaminants of air, water and soil. There are hundreds of different kinds, and some are known carcinogens, but many have not been tested.
Humans are primarily exposed to PAHs in the environment as mixtures, which makes it harder to assess their cancer risk. The standard calculation, Tilton said, is to identify the risk of each element in the mix – if it’s known – and add them together.
But this method doesn’t work with most PAH mixes. It assumes the risk for each component is known, as well as which components are in a given mix. Often that information is not available.
This study examined three PAH mixtures that are common in the environment – coal tar, diesel exhaust and cigarette smoke – and various mixtures of them.
They found that each substance touched off a rapid and distinctive cascade of biological and metabolic changes in the skin cells of a mouse. The response amounted to a unique “fingerprint” of the genetic changes that occur as cells reacted to exposure to each chemical.
By matching patterns of genetic changes known to occur as cells become cancerous, they found that some of the cellular responses were early indicators of developing cancers. They also found that the standard method to calculate carcinogenic material underestimated the cancer risk of some mixtures and overestimated the combined risk of others.
“Our study is a first step in moving away from risk assessments based on individual components of these PAH mixtures and developing more accurate methods that look at the mixture as a whole,” Tilton said. “We’re hoping to bring the methodology to the point where we no longer need to use tumors as our endpoint.”
Tilton collaborated on the research with Katrina Waters of the Pacific Northwest National Laboratory, and others. Their findings appeared in a recent edition of Toxicological Sciences.
The study was funded by NIEHS, which supports the Superfund Research Program, a multi-partner collaboration that includes OSU and PNNL.
David Williams, 541-737-3277 or firstname.lastname@example.org
CORVALLIS, Ore. – Researchers for the first time have developed a method to track through the human body the movement of polycyclic aromatic hydrocarbons, or PAHs, as extraordinarily tiny amounts of these potential carcinogens are biologically processed and eliminated.
PAHs, which are the product of the incomplete combustion of carbon, have been a part of everyday human life since cave dwellers first roasted meat on an open fire. More sophisticated forms of exposure now range from smoked cheese to automobile air pollution, cigarettes, a ham sandwich and public drinking water. PAHs are part of the food we eat, the air we breathe and the water we drink.
However, these same compounds have gained increasing interest and scientific study in recent years due to their role as carcinogens. PAHs or PAH mixtures have been named as three of the top 10 chemicals of concern by the Agency for Toxic Substances Disease Registry.
With this new technology, scientists have an opportunity to study, in a way never before possible, potential cancer-causing compounds as they move through the human body. The findings were just published by researchers from Oregon State University and other institutions in Chemical Research in Toxicology, in work supported by the National Institute of Environmental Health Sciences (NIEHS)
The pioneering work has been the focus of Ph.D. research by Erin Madeen at Oregon State, whose studies were supported in part by an award from the Superfund Research Program at NIEHS for her work at Lawrence Livermore National Laboratory.
“We’ve proven that this technology will work, and it’s going to change the way we’re able to study carcinogenic PAHs,” said David Williams, director of the Superfund Research Program at OSU, a professor in the College of Agricultural Sciences and principal investigator with the Linus Pauling Institute.
“Almost everything we know so far about PAH toxicity is based on giving animals high doses of the compounds and then seeing what happens,” Williams said. “No one before this has ever been able to study these probable carcinogens at normal dietary levels and then see how they move through the body and are changed by various biological processes.”
The technology allowing this to happen is a new application of accelerator mass spectrometry, which as a biological tracking tool is extraordinarily more sensitive than something like radioactivity measuring. Scientists can measure PAH levels in blood down to infinitesimal ratios – comparable to a single drop of water in 4,000 Olympic swimming pools, or to a one-inch increment on a 3-billion mile measuring tape.
As a result, microdoses of a compound, even less than one might find in a normal diet or environmental exposure, can be traced as they are processed by humans. The implications are profound.
“Knowing how people metabolize PAHs may verify a number of animal and cell studies, as well as provide a better understanding of how PAHs work, identifying their mechanism or mechanisms of action,” said Bill Suk, director of the NIEHS Superfund Research Program.
One PAH compound studied in this research, dibenzo (def,p)-chrysene, is fairly potent and defined as a probable human carcinogen. It was administered to volunteers in the study in a capsule equivalent to the level of PAH found in a 5-ounce serving of smoked meat, which provided about 28 percent of the average daily dietary PAH intake. There was a fairly rapid takeup of the compound, reaching a peak metabolic level within about two hours, and then rapid elimination. The researchers were able to study not only the parent compound but also individual metabolites as it was changed.
“Part of what’s so interesting is that we’re able to administer possible carcinogens to people in scientific research and then study the results,” Williams said. “By conventional scientific ethics, that simply would not be allowed. But from a different perspective, we’re not giving these people toxins, we’re giving them dinner. That’s how much PAHs are a part of our everyday lives, and for once we’re able to study these compounds at normal levels of human exposure.”
What a scientist might see as a carcinogen, in other words, is what most of us would see as a nice grilled steak. There are many unexpected forms of PAH exposure. The compounds are found in polluted air, cigarettes, and smoked food, of course, but also in cereal grains, potatoes and at surprisingly high levels in leafy green vegetables.
“It’s clear from our research that PAHs can be toxic, but it’s also clear that there’s more to the equation than just the source of the PAH,” Williams said. “We get most of the more toxic PAHs from our food, rather than inhalation. And some fairly high doses can come from foods like leafy vegetables that we know to be healthy. That’s why we need a better understanding of what’s going on in the human body as these compounds are processed.”
The Williams-led OSU laboratory is recruiting volunteers for a follow-up study that will also employ smoked salmon as a source of a PAH mixture and relate results to an individual’s genetic makeup.
Some of the early findings from the study actually back up previous research fairly well, Williams said, which was done with high-dose studies in laboratory animals. It’s possible, he said, that exposure to dietary PAHs over a lifetime may turn out to be less of a health risk that previously believed at normal levels of exposure, but more work will need to be done with this technology before such conclusions could be reached.
Collaborators on the study were from the Pacific Northwest National Laboratory, Lawrence Livermore National Laboratory, and the OSU Environmental Health Sciences Center.
“Further development and application of this technology could have a major impact in the arena of human environmental health,” the researchers wrote in their conclusion.
The Tanguay group uses the embryonic zebrafish model to demonstrate the utility of high throughput screening for toxicology studies. The group evaluated the 1060 US EPA ToxCast Phase 1 and 2 compounds on 18 distinct outcomes. With four doses for each compound the group generated a dizzying number of data points highlighting the importance of bioinformatics analysis in these types of studies. The study shows how it is now possible to screen many of the tens of thousands of untested chemicals using a whole animal model in which one can literally see developmental malformations. —Gary W. Miller
There are tens of thousands of man-made chemicals in the environment; the inherent safety of most of these chemicals is not known. Relevant biological platforms and new computational tools are needed to prioritize testing of chemicals with limited human health hazard information. We describe an experimental design for high-throughput characterization of multidimensional in vivo effects with the power to evaluate trends relating to commonly cited chemical predictors. We evaluated all 1060 unique U.S. EPA ToxCast phase 1 and 2 compounds using the embryonic zebrafish and found that 487 induced significant adverse biological responses. The utilization of 18 simultaneously measured endpoints means that the entire system serves as a robust biological sensor for chemical hazard. The experimental design enabled us to describe global patterns of variation across tested compounds, evaluate the concordance of the available in vitro and in vivo phase 1 data with this study, highlight specific mechanisms/value-added/novel biology related to notochord development, and demonstrate that the developmental zebrafish detects adverse responses that would be missed by less comprehensive testing strategies.
The Superfund Research Program is federally funded and administered by the National Institute of Environmental Health Sciences (NIEHS grant #P42 ES016465), an institute of the National Institutes of Health.