Duke scientist and collaborators hunt for health risks in records collected for other purposes in North Carolina
By Catherine Clabby
Assessing how your zip code affects your health or your life expectancy is a tough puzzle.
But analyze the right population-scale data, and lots of it, and important clues will emerge.
That’s what Julia Kravchenko is finding. Kravchenko is a Duke University research scientist and physician investigating health differences among people living in unusual environments in North Carolina.
For instance, Kravchenko and collaborators are finding that people residing in North Carolina zip codes hosting densely packed hog farms are more likely to die from one of a host of diseases than are people who do not.
Those diseases include hypertension, aplastic anemia, diabetes and asthma, with the higher mortality persisting even when researchers account for population-level rates of smoking, income, education, whether people have health insurance and other factors.
Residents of counties hosting coal ash waste dumps are more likely to die from Alzheimer’s disease than people living in counties without them, the researchers are also finding. The more waste, the greater the difference.
Let’s be clear: Kravchenko’s preliminary findings do not prove cause and effect. But the results are signals that Kravchenko hopes can be used to improve the aim of studies trying to link environmental exposure to health.
“We’re at the beginning. We’re just describing the problem,” Kravchenko said.
Big data
The Belarus-trained researcher has already successfully demonstrated strong links between environment and health in this state on a decidedly more positive note.
A study she and colleagues published in 2014 found improved air quality in North Carolina accompanied declining death rates from respiratory illnesses such as emphysema, asthma and pneumonia. They did the analysis by comparing mortality trends from state public health data, along with monthly measurements from air-monitoring stations across the state from 1993-2010, capturing changes following passage of the state’s 2002 Clean Smokestacks Act.
“Julia has been a tremendous asset in the field of environmental health research in North Carolina,” said June Blotnick, executive director of CleanAir Carolina. “We have evidence-based research that shows North Carolina’s landmark bipartisan legislation was successful.”
Kravchenko first explored exposure risks in her native Belarus, where she worked at the Institute of Radiation Medicine. There, she helped assess harm from radioactive exposures among clean-up workers and citizens after the 1986 Chernobyl nuclear power plant disaster.
In her work at Duke, Kravchenko collaborates with experts in medicine, epidemiology, data analysis, environmental sciences and public policy to explore risks in the U.S. and abroad. A primary strategy is to mine trends visible in large masses of data that governments collect for other purposes, such as statistics on diseases that prompt hospital admissions, causes of death, air and water pollution monitoring results, cigarette smoking rates, locations and size of hog-raising operations, and data on the tons within coal-ash impoundments.
“The use of ‘big data’ type analysis is important because it leverages and uses in a timely and cost effective manner data that currently exists and is being collected in an ongoing fashion,” said Kim Lyerly, a Duke School of Medicine professor who runs the university’s Environmental Health Scholars program and conducts research with Kravchenko.
“This allows us access to massive amounts of data, which would be cost- and time- prohibitive if we were going to prospectively collect and pay for the collection and storage.”
Environmental differences
When Kravchenko presented preliminary data at the health scholar program’s 2016 Fall Forum, she described ways that counties hosting concentrated animal feeding operations (CAFOS) and coal ash waste might also house distinctive risks.
Densely packed hog farms produce large amounts of manure that can carry pathogens such as E. coli, growth hormones, antibiotics and traces of chemicals used on farms, she explained. And coal ash can contain heavy metals such as arsenic, lead and mercury. In both settings, unwelcome emissions can reach air and water.
But sorting out how either affect people’s health is not simple, Kravchenko stressed. When it comes to the Alzheimer’s disease death indications, it’s important to consider that natural geologic condition produce arsenic in parts of North Carolina, an exposure that can do neurological harm. Studies comparing Alzheimer’s disease among people living near coal ash without natural arsenic could help clarify that risk, she said.
In addition to environmental differences, people who live in counties with large hog farms tend to be poorer than residents in counties that do not. They may have less access to health care, something that needs to be explored and, if confirmed, remedied, Kravchenko said.
To get a better sense of environmental risks from concentrated animal feeding operations (CAFOS), Kravchenko and collaborators intend to use public databases of emissions monitoring results to tackle more detailed studies about what known pollutants are present in the water and air nearby.
She believes the scale of hog farming in this state requires that sort of closer look.
“Almost 200,000 people are living in areas with more than 50 pigs for each human,” Kravchenko said.
Ultimately, she wants her projects to produce sound data that are useful to policymakers and people trying to decide where they will live and raise families. Ideally they could help specify what locations are safer than others.
“Our main objective is to provide people with knowledge,” Kravchenko said.
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