Fresh Lens on Health Disparities Reveals Role of Accumulating Risks

    • October 5, 2011

Persistent health disparities between Black and White Americans have a number of possible causes, and have been the subject of considerable research. But a new study co-authored by Robert Wood Johnson Foundation (RWJF) Health & Society Scholar (2010-2012) Margaret Hicken, PhD, examines disparities through a multi-disciplinary lens, bringing together research on the science of illness, environmental hazards and relevant social factors.

By examining health disparities in light of these other bodies of research, Hicken and her colleagues observe an interplay of factors that could offer a key to combating disparities.

Hicken and her University of Michigan colleague Howard Hu, MD, MPH, ScD, together with Richard Gragg, PhD, MS, of Florida A&M University, note in an article in the October 2011 edition of Health Affairs that Blacks have “persistently higher rates of high blood pressure, or hypertension, compared to whites,” resulting both in higher mortality rates and higher health care costs. The researchers go on to connect that medical finding with two other findings that have been the subject of research in non-medical disciplines: elevated lead levels among Blacks, resulting from lead pollution; and increased levels of self-reported perceptions of stress among people with hypertension – high blood pressure. Then they connect the dots, concluding that “social and environmental factors—such as high levels of stress and exposure to lead—may explain racial disparities in hypertension.”

“The main lesson,” says Hicken, “is that we need to shift our approaches to health disparities away from the biomedical model and pay more attention to social and environmental risks…. I think it’s a mindset issue. And that drives some institutional barriers. We hold biomedical determinants of health in such high regard, and we have some of the best medical technology. And yet the United States lags far behind other countries in some health outcomes, because of our great disparities in health. So I think it has to begin with a mindset; people have to believe that these social and environmental factors matter – things like neighborhoods, employment policy and the environment.” Changing the research mindset will help bring down institutional barriers, she says, noting that at many universities, “it’s very hard to fund true multidisciplinary research, and hard to share across departments.”

Multidisciplinary Data

According to Hicken and her colleagues, about 33 percent of the White population lives with high blood pressure compared to 43 percent of the Black population. Since hypertension is linked to a variety of health conditions, including heart attacks, stroke, aneurisms, kidney problems and more, the disparate rates of hypertension translate to more illness and shorter lives for Black Americans.

The authors write that past research into what drives the disparity has focused on behavior and genetics. They think that conclusion misses important factors. Drawing on research from environmental scientists, they note that Blacks have “historically experienced more environmental lead exposure compared to Whites.” They cite a study from the 1970s that found that roughly 23 percent of Blacks had lead levels in their blood that were considered high, compared to 14 percent of Whites.

Since then, exposure to lead has decreased significantly, largely as a result of Environmental Protection Agency regulations banning lead from gasoline and other products containing the neurotoxin. The resulting reduction in blood lead levels has been significant, but it has not eliminated the problem. “Lead continues to be an important environmental hazard for adults, particularly for racial minorities,” the authors write. “Historical disparities in lead exposure are important [because] our bones store lead for decades, making bone lead a potential internal exposure source—particularly during times of bone loss such as pregnancy and menopause—long after external exposures have abated.” They go on to explain that while data about bone lead levels in non-whites are scarce, the few studies that are available indicate even larger racial disparities on bone lead levels than blood lead levels, “reflecting the historical disparities in lead exposure.”

Compounding the hazard is the finding from other research suggesting that elevated levels of stress among minorities are also a factor. They write,

Several new studies suggest that stress increases vulnerability to the hypertensive effects of lead. In a 2007 study, researchers examined the role of perceptions of stress in the association between bone lead and the risk of developing later hypertension in men. They reported that men who perceived high levels of stress in their lives have more than double the risk of developing lead-related hypertension compared to men who perceived low levels of stress…. Although not yet examined in Black populations, these results, taken together, suggest that even at current low levels of blood lead and low disparities, the widely documented racial disparities in such factors as stress can result in disparities in lead-related morbidity and mortality….

On the one hand, these communities experience more frequent exposure to multiple environmental hazards over their lifespan compared to more advantaged communities…. On the other hand, socially disadvantaged communities also experience greater levels of exposure to multiple factors that increase vulnerability to the health effects of environmental hazards. In other words, they are more likely to experience high stress, along with other social and economic factors that may increase vulnerability.

A Fundamental Shift

The authors conclude that a “fundamental shift in the approach to racial health disparities” is in order, one that accounts for the cumulative effect of social and environmental health risks. They call on researchers and government agencies to “develop strategic plans to learn more about [such] connections and apply the broader findings to policies to reduce health disparities.” They go on to urge the development of tools to better measure environmental exposure and the cumulative social and environmental risk of such exposures. Finally, they write that health issues need to be given higher priority in setting social and economic policies in general.

“Unfortunately,” Hicken says, “when policies are made, it often ends up that the most socially disadvantaged communities are the ones who bear the brunt of the social risk exposures—poverty, crime, toxic waste, proximity to roadways and resulting air pollution, and more. But these health factors are not always considered. Our analysis of the literature suggests that in order to address disparities, we need to step back from the biomedical factors and look more closely at the social and environmental ones.”

The Robert Wood Johnson Foundation Health & Society Scholars program is designed to build the nation’s capacity for research, leadership and policy change to address the multiple determinants of population health. The program enables up to 12 outstanding individuals who have completed their doctoral training to engage in an intensive two-year program at one of six nationally prominent universities: Columbia University; Harvard University; the University of California, San Francisco and Berkeley; the University of Michigan; the University of Pennsylvania; and the University of Wisconsin.