摘要：Environmental exposures are a leading cause of morbidity and mortality worldwide. The burden of disease resulting from these exposures is expected to intensify over time and directly contribute to a subsequent rise in associated noncommunicable diseases.
1–
5
In a 2015 analysis estimating the global burden of air pollution, ambient fine particulate matter [PM
≤
2.5
μ
m
in aerodynamic diameter (
PM
2.5
)] was considered the fifth leading risk factor for death, directly contributing to at least 7.6% of deaths worldwide.
2
Furthermore, chronic
PM
2.5
exposures, which are unavoidable given that we breathe air to survive, contribute to cardiopulmonary diseases,
6–
9
cancer,
7,
10
and diabetes mellitus.
8,
11
Unfortunately, exposures to
PM
2.5
and many other environmental agents may be magnified in immigrants. In this issue of
Environmental Health Perspectives, Fong et al.
12
present a timely scoping review demonstrating disparities in community-level environmental exposures among immigrant populations.
The relationship between environmental pollution, exposure, and disease is complex.
8,
13
To affect health outcomes, contaminants must be released, enter the body, and accumulate to induce biological change.
13
Compounding exposures may amplify adverse effects, such as is the case in the development of lung cancer.
14,
15
In addition, immigrants and other vulnerable populations often engage in certain occupations
16
and live
17,
18
in certain communities that impart greater exposures to potentially harmful agents, further widening health disparities where many of these risk factors intersect.
The literature to date spans numerous exposures, settings, and countries. Among immigrant populations, Fong et al. identified studies that reported disparities in exposure to multiple inhalable air pollutants, metals, and organic chemicals.
12
The literature suggests that living in high-immigrant, urban-core communities is associated with higher blood concentrations of metals, heat exposures, and ambient air concentrations of black carbon, ozone, and
PM
2.5
.
12
The review authors note that immigrants often settle in so-called gateway cities, where they may have family or cultural ties. Within cities, immigrants with limited means are more likely to live in urban-core communities, disproportionately exposing them to metals, heat, ambient air pollution, and other environmental hazards. These exposures at home do not account for the potential additive effects of occupational exposures. A survey of
>
10,000
U.S. adults suggested that U.S. adults think that immigrants were more likely to pursue occupations in construction (including painting and roofing), maintenance, natural resource extraction, transportation, and material moving.
19
Unresolved health problems may limit immigrants’ ability to maintain their jobs, particularly when their occupations could disproportionately expose them to more harmful environmental exposures.
16,
20,
21
Immigrants tend not to seek medical attention due to financial constraints, communication barriers, discrimination, and fear of deportation.
16,
19,
22–
29
Moreover, immigrants are vulnerable to so-called medical repatriation, causing families to avoid necessary medical services and forgo public health insurance, which could have allowed for increased health care access.
16,
19,
22–
29
In the United States, hospitals are required to provide emergency medical care to patients regardless of immigration or insurance status,
29
an obligation that ends once the patient is stable. In medical repatriation, hospitals transfer undocumented patients in need of subacute care to their country of origin without the involvement of federal immigration authorities. This, in addition to gross humanitarian concerns, exacerbates already poor access to health care.
30–
34
One fundamental step Fong et al.
12
did not take was to run a parallel scoping review to determine how occupational exposures in immigrants may demonstrate similar disparities. This would help us understand how immigrants are disproportionately affected in every aspect of life. How additive are these environmental exposures? How do these exposure disparities affect health outcomes in immigrants? Fong et al. also mention multiple studies suggesting higher blood concentrations of harmful chemicals in immigrants compared with their nonimmigrant counterparts, despite having the same occupations and residing in the same areas.
12
This may be indicative of other relevant factors driving exposures, including cultural differences. In fact, that is strongly suggested by the direct relationship of country of origin and time since immigration on exposure disparities.
12
Unfortunately, the review by Fong et al. has minimal discussion of these factors. We recommend that future scoping reviews address these questions. This would help identify key areas of interest for intervention and policy.
Fong et al. conclude that researchers and policy makers must give immigrant health disparities the attention they deserve.
12
As a reference point, disparities in poor health outcomes among non-Hispanic Black communities, along with other vulnerable populations, are well documented.
17,
18,
30–
33,
35–
37
These disparities are unacceptable; thankfully, they are now being actively addressed for multiple diseases.
34,
38–
41
The frank discussion of how racism is intertwined with these disparities is driving efforts for achieving health equity.
38–
41
We must take similar actions in reporting, understanding, and discussing how factors unique to immigrants interact to worsen environmental exposures and, potentially, health outcomes, among these populations. Moving forward, we must ensure that health equity discussions include every population. Having used broad search terms such as “US born” and “immigrant,” Fong et al. acknowledge they may not have captured pertinent studies conducted outside the United States.
12
We must recognize that immigrant groups—including refugees, international students and professionals on visas, migrant workers, and undocumented immigrants—are severely underrepresented in research. This may be inadvertent given that information regarding immigration status is often sensitive to disclose and not routinely documented in medical records.
42
Unfortunately, it inherently limits our ability to understand health disparities among documented and undocumented immigrants.
Although we do recommend further studies to strengthen our knowledge base and to guide these changes in research, we also urge policy makers to start discussions for change now. We should not wait on additional studies “proving” immigrant health disparities and deaths to act. Thank you, Fong et al. for taking an important step in supporting the health of immigrants. Stay tuned.
