Understanding the cumulative impacts of inequalities in environmental health: implications for policy.

TL;DR: Current environmental policy should be broadened to take into account the cumulative impact of exposures and vulnerabilities encountered by people who live in neighborhoods consisting largely of racial or ethnic minorities or people of low socioeconomic status.

Abstract: Racial or ethnic minority groups and low-income communities have poorer health outcomes than others. They are more frequently exposed to multiple environmental hazards and social stressors, including poverty, poor housing quality, and social inequality. Researchers are grappling with how best to characterize the cumulative effects of these hazards and stressors in order to help regulators and decision makers craft more-effective policies to address health and environmental disparities. In this article we synthesize the existing scientific evidence regarding the cumulative health implications of higher rates of exposure to environmental hazards, along with individual biological susceptibility and social vulnerability. We conclude that current environmental policy, which is focused narrowly on pollutants and their sources, should be broadened to take into account the cumulative impact of exposures and vulnerabilities encountered by people who live in neighborhoods consisting largely of racial or ethnic minorities or people of low socioeconomic status.

Summary

Understanding The Cumulative Impacts Of Inequalities

• Implications For Policy ABSTRACT, also known as In Environmental Health.
• Along with individual biological susceptibility and social vulnerability.the authors.
• Advocates for such communities have long argued that their neighborhoods are beset by multiple environmental stressors, which could include air and water pollution and substandard housing.
• Research is beginning to show how the cumulative effects of social and environmental stressors can work in combination to produce health disparities.
• The authors highlight the evidence for these four concepts and conclude with a discussion of how this scientific foundation can help reshape regulatory science and decision making to reduce environmental health disparities and promote environmental justice among diverse communities.

Health Disparities

• Research has documented systemic disparities in the incidence and severity of diseases between socioeconomic and racial or ethnic groups.
• These differences can result in higher risks of long-term health problems such as cognitive deficits, cardiovascular disease, and diabetes.
• 8 Socioeconomic and behavioral factors such as the mother's education, access to prenatal care, and substance use have been shown to contribute to poor perinatal outcomes-again, low birthweight and prematurity among them.
• 12 Neighborhood environments have been linked to both the prevalence of heart disease and its risk factors.
• 18 Researchers have found that racial disparities in self-rated health persist even after differences in socioeconomic status are controlled for.

Environmental Hazard Inequalities

• Greater exposure to environmental hazards is one driver of health disparities found among communities of racial or ethnic minorities and those of low socioeconomic status.
• 42 For example, residents of disadvantaged neighborhoods are exposed to more fast-food restaurants 43 and liquor stores than members of other communities.
• 44 As noted above, poor communities also suffer from a dearth of health-promoting resources such as healthy food, 22 green spaces, and recreational programs, 23 whose lack can contribute to disparities in obesity rates and stress levels.

Intrinsic Factors: Biological Susceptibility

• The authors use the term susceptibility to refer to intrinsic biological traits related to age, genetics, or preexisting health conditions that can create much variability in response to environmental stressors within a population.
• Age Children and the elderly experience heightened risk of pollution-related morbidity and mortality.
• 47 Children's susceptibility is associated with differences in rates of absorption, distribution, metabolism, and excretion of chemicals.
• These exposures may modify the patterns of gene expression-that is, turn genes "on" or "off"-which in turn triggers physiologic Poor communities suffer from a dearth of health-promoting resources.
• 51, 52 In the United States, African Americans, Hispanics, and people of low socioeconomic status have higher rates of obesity, cardiovascular disease, and type 2 diabetes and are therefore more susceptible to environmental stressors.

Extrinsic Factors: Social Vulnerability

• The authors use the term vulnerability when describing how social constructs of race and class can amplify the effects of environmental exposures, with a focus on the pathway of psychosocial stress.
• The authors classify race as a social construct and not as a proxy for biological differences because research has consistently shown that race is a poor indicator for genetic variation in human populations and therefore should be understood as a social rather than biological category.
• Extrinsic factors that are socially related-such as race, ethnicity, socioeconomic status, and sex-can enhance the adverse effects of environmental exposures, such as short-and long-term exposures to air pollution.
• 58 Psychosocial pathways may link race and socioeconomic measures at the individual and area levels with the increased adverse impacts of environmental stressors.

Discussion

• The authors have synthesized the scientific evidence underlying the cumulative impacts of environmental and social stressors and the multiple ways they can have a greater impact on communities of people who belong to racial or ethnic minority groups or are of low socioeconomic status.
• Researchers have established many dimensions of social vulnerability such as human and political capital, discrimination, and features of the built environment, 2 which should be taken into account in environmental health research and assessment practices.
• Health impact assessment may provide a promising path for incorporating cumulative impacts into assessments to guide decision making.
• The use of cumulative impact screening could remove this burden of proof from vulnerable communities and increase the likelihood that disadvantaged neighborhoods will receive focused regulatory attention.
• 76 Similarly, Los Angeles is considering a "green zones" ordinance, which would use cumulative impact screening to guide municipal planning, the issuing of permits, and enforcement strategies to mitigate and reduce environmental hazards in disproportionately affected neighborhoods.

Conclusion

• Communities of racial or ethnic minorities or people of low socioeconomic status are particularly vulnerable to environmental and social stressors.
• More holistic and transparent approaches to the regulatory science underlying decision making that affects such communities are needed.
• Screening methods can help regulators and policy makers more efficiently target efforts to remediate the cumulative effects of these exposures and environmental inequities, and to focus regulatory action at the neighborhood and regional levels.
• Because industrial and transportation development, as well as other land-use planning decisions, are often rooted within metropolitan regions and neighborhoods, regulatory interventions to mitigate the cumulative impact of environmental and social stressors on the health of disadvantaged communities will require multilevel, placed-based strategies.

Full text

UC Berkeley
UC Berkeley Previously Published Works
Title
Understanding the cumulative impacts of inequalities in environmental health:
implications for policy.
Permalink
https://escholarship.org/uc/item/1kq0196d
Journal
Health affairs (Project Hope), 30(5)
ISSN
0278-2715
Authors
Morello-Frosch, Rachel
Zuk, Miriam
Jerrett, Michael
et al.
Publication Date
2011-05-01
DOI
10.1377/hlthaff.2011.0153
Peer reviewed
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University of California

At the Intersection of Health, Health Care and Policy
doi: 10.1377/hlthaff.2011.0153
30, no.5 (2011):879-887Health Affairs
Implications For Policy
Understanding The Cumulative Impacts Of Inequalities In Environmental Health:
Amy D. Kyle
Rachel Morello-Frosch, Miriam Zuk, Michael Jerrett, Bhavna Shamasunder and
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By Rachel Morello-Frosch, Miriam Zuk, Michael Jerrett, Bhavna Shamasunder, and Amy D. Kyle
Understanding The Cumulative
Impacts Of Inequalities
In Environmental Health:
Implications For Policy
ABSTRACT
Racial or ethnic minority groups and low-income communities
have poorer health outcomes than others. They are more frequently
exposed to multiple environmental hazards and social stressors,
including poverty, poor housing quality, and social inequality.
Researchers are grappling with how best to characterize the cumulative
effects of these hazards and stressors in order to help regulators and
decision makers craft more-effective policies to address health and
environmental disparities. In this article we synthesize the existing
scientific evidence regarding the cumulative health implications of higher
rates of exposure to environmental hazards, along with individual
biological susceptibility and social vulnerability. We conclude that current
environmental policy, which is focused narrowly on pollutants and their
sources, should be broadened to take into account the cumulative impact
of exposures and vulnerabilities encountered by people who live in
neighborhoods consisting largely of racial or ethnic minorities or people
of low socioeconomic status.
T
he persistence of health disparities
and environmental inequalities in
the United States has placed envi-
ronmental health science and pol-
icy at a crossroads. Innovative sci-
entific and regulatory approaches are needed to
understand and address the cumulative, and po-
tentially synergistic, effects of environmental
and social stressors on the health of commun-
ities whose populations are mostly composed of
racial or ethnic minorities or people of low socio-
economic status.
Advocates for such communities have long ar-
gued that their neighborhoods are beset by
multiple environmental stressors, which could
include air and water pollution and substandard
housing. These community leaders also contend
that existing regulations fail to protect residents
adequately because the regulations are focused
narrowly on pollutants and their sources.
1
Grow-
ing evidence shows that social stressors—includ-
ing poverty, racial discrimination, crime, malnu-
trition, and substance abuse—also affect these
communities.
2
Research is beginning to show
how the cumulative effects of social and environ-
mental stressors can work in combination to
produce health disparities.
3
With encouragement from scientists, policy
makers, and environmental justice groups, regu-
latory agencies are beginning to consider the
methodological challenges of addressing cumu-
lative impacts in science and decision making.
4–6
These methodological challenges include how to
evaluate and characterize the combined health
effects of multiple environmental and social
stressors on vulnerable populations, including
the stressors’ sources and the pathways of dis-
eases. For example, the US Environmental Pro-
tection Agency has proposed a model for includ-
ing psychological and social factors as integral
components of cumulative risk assessment for
predicting the potential health effects of pollu-
doi: 10.1377/hlthaff.2011.0153
HEALTH AFFAIR S 30,
NO. 5 (2011): 879– 887
©2011 Project HOPE—
The People-to-People H ealth
Foundation, Inc.
Rachel Morello-Frosch (rmf@
berkeley.edu) is an associate
professor in the Department
of En vironmental Scienc e,
Policy, and Management and
in the School of Public Health
at th e U niversity of Cal ifornia
(UC), Berkeley.
Miriam Zuk is a gradua te
student in city a nd regional
planning at UC Berkeley.
Michael Jerrett is an
associate professor in the
Division of Environmental
Health Sciences at the School
of Pub lic Health, UC Berkeley.
Bhavna Shamasunder is a
graduate student in the
Department of Environmental
Science, Policy, and
Management at UC Berkeley.
Amy D. Kyle i s an associate
adjunct professor in the
Division of Environmental
Health Scienc es, School of
Public Health, UC Berkeley.
May 2011 30:5 Health Affairs 879
Racial
&
Ethnic Disparities
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tion exposures in vulnerable populations.
7
This article presents a synthesis of relevant
research from the fields of social and environ-
mental epidemiology, exposure assessment, and
environmental justice. We believe that four key
concepts underlie the emerging knowledge
about the cumulative impacts of exposure to
environmental hazards and social stressors.
First, health disparities between groups of dif-
ferent racial or ethnic makeup or socioeconomic
status are significant and persistent, and exist
for diseases that are linked to social and environ-
mental factors. Second, inequalities in expo-
sures to environmental hazards are also signifi-
cant and persistent, and are linked to adverse
health outcomes. Third, intrinsic biological
and physiological factors—for example, age or
genetic makeup—can modify the effects of envi-
ronmental factors and contribute to differences
in the frequency and severity of environmentally
related disease. And fourth, extrinsic social vul-
nerability factors at the individual and commu-
nity levels—such as race, sex, and socioeconomic
status—may amplify the adverse effects of envi-
ronmental hazards and can contribute to health
disparities.
We highlight the evidence for these four con-
cepts and conclude with a discussion of how this
scientific foundation can help reshape regula-
tory science and decision making to reduce envi-
ronmental health disparities and promote envi-
ronmental justice among diverse communities.
Health Disparities
Research has documented systemic disparities in
the incidence and severity of diseases between
socioeconomic and racial or ethnic groups. A
wide range of material, behavioral, psychosocial,
environmental, and biological factors have been
proposed to explain why social status is persist-
ently linked to health.
2
Three health outcomes
have been shown to be associated with both so-
cial and environmental stressors: adverse peri-
natal outcomes such as low birthweight and pre-
maturity, cardiovascular disease, and self-rated
health.
Perinatal Outcomes African American in-
fants are more likely to be delivered preterm
and have low birthweight than white infants.
These differences can result in higher risks of
long-term health problems such as cognitive def-
icits, cardiovascular disease, and diabetes.
8
Socioeconomic and behavioral factors such as
the mother’s education, access to prenatal care,
and substance use have been shown to contrib-
ute to poor perinatal outcomes—again, low
birthweight and prematurity among them.
8
Re-
search also indicates that prenatal stress result-
ing from maternal perceived discrimination,
neighborhood deprivation, segregation, and in-
come inequality are also linked to these poor
perinatal outcomes, which suggests the impor-
tance of psychosocial pathways in the produc-
tion of these racial or ethnic disparities.
9,10
Cardiovascular Disease African Americans
and people of low socioeconomic status have
significantly higher rates of hypertension, heart
disease, and stroke than whites and people of
higher socioeconomic status.
11
Cardiovascular
disease disparities have been linked to differenc-
es in biological risk factors such as diabetes,
behavior such as physical inactivity, and the
availability and use of primary and secondary
preventive services.
12
Neighborhood environ-
ments have been linked to both the prevalence
of heart disease and its risk factors.
13
Environ-
mental pollutants, such as lead and ambient par-
ticulate matter—for example, extremely fine par-
ticles released into the air by vehicles and
industrial plants that burn fossil fuels—have
been linked to higher risk of cardiovascular
disease.
14,15
Emerging research has also linked the risk of
developing cardiovascular disease in adulthood
to early life events such as prenatal stress, which
can disrupt development and cause heritable
changes in gene expression. These so-called epi-
genetic changes can affect which genes are
switched “on” or “off,” which in turn can be
associated with heightened disease risk.
16
Self-Rated Health Self-rated health—a
well-validated predictor of mortality, physical
disability, chronic disease status, and health
behavior
17
—is lower among racial and ethnic
minorities and people of low socioeconomic sta-
tus than others.
18
Researchers have found that
racial disparities in self-rated health persist even
after differences in socioeconomic status are
controlled for.
19
The neighborhood people live
in has been found to account for a large portion
of the disparities between the way African Amer-
icans and whites rate their own health status.
20
This difference may be related to factors such as
individual socioeconomic status, perceptions of
neighborhood quality, health behavior, environ-
mental quality, and psychosocial stress.
21
Environmental Hazard Inequalities
Greater exposure to environmental hazards is
one driver of health disparities found among
communities of racial or ethnic minorities and
those of low socioeconomic status. Research in
this field has expanded from an initial focus on
how close residents live to an environmental
hazard, such as a highway or a major industrial
facility, to encompass a broader investigation of
Racial
&
Ethnic Disparities
880 Health Affairs May 2011 30:5
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the role that place plays in health. For example, a
poor community populated by racial or ethnic
minorities may also lack healthy food options,
22
high-quality green spaces, and recreational pro-
grams.
23
The lack of these positive factors can
contribute to poor health.
Proximity To Polluting Land U ses And
Toxic Emissions Numerous studies have docu-
mented the disproportionate location of hazard-
ous waste sites, industrial facilities, sewage treat-
ment plants, and other locally undesirable and
potentially polluting land uses in communities
of racial or ethnic minorities and in socially dis-
advantaged neighborhoods.
24–26
Residents living
near such facilities can be exposed to more pol-
lutants than people who live in more affluent
neighborhoods located farther from these sour-
ces of pollution.
27
The residents of communities near industrial
and hazardous waste sites experience an in-
creased risk of adverse perinatal outcomes, res-
piratory and heart diseases, psychosocial stress,
and mental health impacts.
28,29
Members of ra-
cial or ethnic minority groups and people of low
socioeconomic status are also more likely than
others to live near busy roads, where traffic-
related air pollutants concentrate.
30
Research
has linked a wide array of adverse health out-
comes to residential proximity to traffic, includ-
ing asthma,
31
low birthweight,
32
cardiovascular
disease,
33
and premature mortality.
34
Exposur e s To Pollutants The poor and ra-
cial or ethnic minorities are disproportionately
exposed to ambient air pollutants, which have
been linked to respiratory and cardiovascular
disease, adverse perinatal outcomes, diabetes,
premature mortality, and other adverse ef-
fects.
35–38
Indoor environments also contribute
to exposure disparities. Studies have found
higher levels of indoor pollutants such as lead-
based paint
39
and pollutants from industrial and
transportation sources
40
in poor, African Ameri-
can, and Hispanic households than in other
households.
Occupational exposures also constitute a
source of environmental inequalities. For in-
stance, Mexican American farm workers experi-
ence heightened exposure to organophosphate
pesticides, which are associated with increased
risk of cancer; preterm birth; and neurological,
cardiovascular, and respiratory diseases.
41
Neighborhood Environments Poor com-
munities have an excess of health-damaging fac-
tors and a shortage of health-promoting amen-
ities.
42
For example, residents of disadvantaged
neighborhoods are exposed to more fast-food
restaurants
43
and liquor stores than members
of other communities. In particular, the pres-
ence of neighborhood liquor stores can influ-
ence health behavior and violence and can affect
health both directly and indirectly.
44
As noted above, poor communities also suffer
from a dearth of health-promoting resources
such as healthy food,
22
green spaces, and recrea-
tional programs,
23
whose lack can contribute to
disparities in obesity rates and stress levels.
45,46
The confluence of these and other place-based
factors contribute to the association between
neighborhood socioeconomic status and adverse
health outcomes.
20
Intrinsic Factors: Biological
Susceptibility
We use the term susceptibility to refer to intrinsic
biological traits related to age, genetics, or pre-
existing health conditions that can create much
variability in response to environmental stress-
ors within a population.
Age Children and the elderly experience
heightened risk of pollution-related morbidity
and mortality. The elderly are more susceptible
to pollutant exposures because of their altered
immune response and weakened respiratory and
cardiovascular systems.
47
Children’s susceptibil-
ity is associated with differences in rates of ab-
sorption, distribution, metabolism, and excre-
tion of chemicals.
48
Exposure to stressors
during childhood can greatly affect the develop-
ment and functioning of organ systems well into
adulthood.
49
Children have the potential for in-
creased exposures to pollution because of their
physical and behavioral activities, such as play-
ing outside and frequent hand-to-mouth activity.
Thus, their biological susceptibility combined
with greater exposure to potentially toxic sub-
stances may put them at increased risk.
Genetics And Gene Expression Studies have
found that certain genetic variants increase the
effect of air pollution on respiratory symptoms,
lung functioning, and asthma.
50
Where a child
lives early in life, and the substances he or she is
exposed to, can affect the development of disease
in later life. These exposures may modify the
patterns of gene expression—that is, turn genes
“on” or “off”—which in turn triggers physiologic
Poor communities
suffer from a dearth
of health-promoting
resources.
May 2011 30:5 Health Affairs 881
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Frequently asked questions

Q1. What are the contributions in this paper?

In this article the authors synthesize the existing scientific evidence regarding the cumulative health implications of higher rates of exposure to environmental hazards, along with individual biological susceptibility and social vulnerability. Innovative scientific and regulatory approaches are needed to understand and address the cumulative, and potentially synergistic, effects of environmental and social stressors on the health of communities whose populations are mostly composed of racial or ethnicminorities or people of low socioeconomic status. For example, the US Environmental Protection Agency has proposed a model for including psychological and social factors as integral components of cumulative risk assessment for predicting the potential health effects of polludoi: 10.