Modification of the PM2.5- and extreme heat-mortality relationships by historical redlining: a case-crossover study in thirteen U.S. states.

BACKGROUND: Redlining has been associated with worse health outcomes and various environmental disparities, separately, but little is known of the interaction between these two factors, if any. We aimed to estimate whether living in a historically-redlined area modifies the effects of exposures to ambient PM2.5 and extreme heat on mortality by non-external causes. METHODS: We merged 8,884,733 adult mortality records from thirteen state departments of public health with scanned and georeferenced Home Owners Loan Corporation (HOLC) maps from the University of Richmond, daily average PM2.5 from a sophisticated prediction model on a 1-km grid, and daily temperature and vapor pressure from the Daymet V4 1-km grid. A case-crossover approach was used to assess modification of the effects of ambient PM2.5 and extreme heat exposures by redlining and control for all fixed and slow-varying factors by design. Multiple moving averages of PM2.5 and duration-aware analyses of extreme heat were used to assess the most vulnerable time windows. RESULTS: We found significant statistical interactions between living in a redlined area and exposures to both ambient PM2.5 and extreme heat. Individuals who lived in redlined areas had an interaction odds ratio for mortality of 1.0093 (95% confidence interval [CI]: 1.0084, 1.0101) for each 10 µg m-3 increase in same-day ambient PM2.5 compared to individuals who did not live in redlined areas. For extreme heat, the interaction odds ratio was 1.0218 (95% CI 1.0031, 1.0408). CONCLUSIONS: Living in areas that were historically-redlined in the 1930's increases the effects of exposures to both PM2.5 and extreme heat on mortality by non-external causes, suggesting that interventions to reduce environmental health disparities can be more effective by also considering the social context of an area and how to reduce disparities there. Further study is required to ascertain the specific pathways through which this effect modification operates and to develop interventions that can contribute to health equity for individuals living in these areas.

Prenatal exposure to particulate air pollution and gestational age at delivery in Massachusetts neonates 2001-2015: A perspective of causal modeling and health disparities.

There is a lack of evidence on causal effects of air pollution on gestational age (GA) at delivery. METHODS: Inverse probability weighting (IPW) quantile regression was applied to derive causal marginal population-level GA reduction for GA percentiles associated with increased ambient particulate matter with diameter <2.5 µm (PM2.5) levels at maternal residential address for each trimester and the month preceding delivery using Massachusetts birth registry 2001 to 2015. Stratified analyses were conducted for neonatal sex, maternal age/race/education, and extreme ambient temperature conditions. RESULTS: For neonates at 2.5th, 10th, 25th, 50th, 75th, and 97.5th percentiles of GA at delivery, we estimated an adjusted GA reduction of 4.2 days (95% confidence interval [CI] = 3.4, 5.0), 1.9 days (1.6, 2.1), 1.2 days (1.0, 1.4), 0.82 days (0.72, 0.92), 0.74 days (0.54, 0.94), and 0.54 days (0.15, 0.93) for each 5 µg/m3 increment in third trimester average PM2.5 levels. Final gestational month average exposure yielded a similar effect with greater magnitude. Male neonates and neonates of younger (younger than 35 years) and African American mothers as well as with high/low extreme temperature exposure in third trimester were more affected. Estimates were consistently higher at lower GA percentiles, indicating preterm/early-term births being more affected. Low-exposure analyses yielded similar results, restricting to areas with PM2.5 levels under US ambient annual standard of 12 µg/m3. CONCLUSIONS: Prenatal exposure to PM2.5 in late pregnancy reduced GA at delivery among Massachusetts neonates, especially among preterm/early-term births, male neonates, and neonates of younger and African American mothers. Exposure to extremely high/low temperature amplifies the effect of PM2.5 on GA.

Fine Particulate Air Pollution and Birthweight: Differences in Associations Along the Birthweight Distribution.

BACKGROUND: Maternal exposure to fine particulate air pollution (PM2.5) during pregnancy is associated with lower newborn birthweight, which is a risk factor for chronic disease. Existing studies typically report the average association related with PM2.5 increase, which does not offer information about potentially varying associations at different points of the birthweight distribution. METHODS: We retrieved all birth records in Massachusetts between 2001 and 2013 then restricted our analysis to full-term live singletons (n = 775,768). Using the birthdate, gestational age, and residential address reported at time of birth, we estimated the average maternal PM2.5 exposure during pregnancy of each birth. PM2.5 predictions came from a model that incorporates satellite, land use, and meteorologic data. We applied quantile regression to quantify the association between PM2.5 and birthweight at each decile of birthweight, adjusted for individual and neighborhood covariates. We considered effect modification by indicators of individual and neighborhood socioeconomic status (SES). RESULTS: PM2.5 was negatively associated with birthweight. An interquartile range increase in PM2.5 was associated with a 16 g [95% confidence interval (CI) = 13, 19] lower birthweight on average, 19 g (95% CI = 15, 23) lower birthweight at the lowest decile of birthweight, and 14 g (95% CI = 9, 19) lower birthweight at the highest decile. In general, the magnitudes of negative associations were larger at lower deciles. We did not find evidence of effect modification by individual or neighborhood SES. CONCLUSIONS: In full-term live births, PM2.5 and birthweight were negatively associated with more severe associations at lower quantiles of birthweight.

Heat stroke admissions during heat waves in 1,916 US counties for the period from 1999 to 2010 and their effect modifiers.

BACKGROUND: Heat stroke is a serious heat-related illness, especially among older adults. However, little is known regarding the spatiotemporal variation of heat stroke admissions during heat waves and what factors modify the adverse effects. METHODS: We conducted a large-scale national study among 23.5 million Medicare fee-for-service beneficiaries per year residing in 1,916 US counties during 1999-2010. Heat wave days, defined as a period of at least two consecutive days with temperatures exceeding the 97th percentile of that county's temperatures, were matched to non-heat wave days by county and week. We fitted random-effects Poisson regression models to estimate the relative risk (RR) of heat stroke admissions on a heat wave day as compared to a matched non-heat wave day. A variety of effect modifiers were tested including individual-level covariates, community-level covariates, meteorological conditions, and the intensity and duration of the heat wave event. RESULTS: The RR declined substantially from 71.0 (21.3-236.2) in 1999 to 3.5 (1.9-6.5) in 2010, and was highest in the northeast and lowest in the west north central regions of the US. We found a lower RR among counties with higher central air conditioning (AC) prevalence. More severe and longer-lasting heat waves had higher RRs. CONCLUSIONS: Heat stroke hospitalizations associated with heat waves declined dramatically over time, indicating increased resilience to extreme heat among older adults. Considerable risks, however, still remain through 2010, which could be addressed through public health interventions at a regional scale to further increase central AC and monitoring heat waves.

Age at menarche: 50-year socioeconomic trends among US-born black and white women.

OBJECTIVES: We investigated 50-year US trends in age at menarche by socioeconomic position (SEP) and race/ethnicity because data are scant and contradictory. METHODS: We analyzed data by income and education for US-born non-Hispanic Black and White women aged 25 to 74 years in the National Health Examination Survey (NHES) I (1959-1962), National Health Examination and Nutrition Surveys (NHANES) I-III (1971-1994), and NHANES 1999-2008. RESULTS: In NHES I, average age at menarche among White women in the 20th (lowest) versus 80th (highest) income percentiles was 0.26 years higher (95% confidence interval [CI] = -0.09, 0.61), but by NHANES 2005-2008 it had reversed and was -0.33 years lower (95% CI = -0.54, -0.11); no socioeconomic gradients occurred among Black women. The proportion with onset at younger than 11 years increased only among women with low SEP, among Blacks and Whites (P for trend < .05), and high rates of change occurred solely among Black women (all SEP strata) and low-income White women who underwent menarche before 1960. CONCLUSIONS: Trends in US age at menarche vary by SEP and race/ethnicity in ways that pose challenges to several leading clinical, public health, and social explanations for early age at menarche and that underscore why analyses must jointly include data on race/ethnicity and socioeconomic position. Future research is needed to explain these trends.

50-year trends in US socioeconomic inequalities in health: US-born Black and White Americans, 1959-2008.

BACKGROUND: Debates exist over whether health inequities are bound to rise as population health improves, due to health improving more quickly among the better off, with most analyses focused on mortality data. METHODS: We analysed 50 years of socioeconomic inequities in measured health status among US-born Black and White Americans, using data from the National Health Examination Surveys (NHES) I-III (1959-70), National Health and Nutrition Examination Surveys (NHANES) I-III (1971-94) and NHANES 1999-2008. RESULTS: Absolute US socioeconomic health inequities for income percentile and education variously decreased (serum cholesterol; childhood height), stagnated [systolic blood pressure (SBP)], widened [body mass index (BMI), waist circumference (WC)] and in some cases reversed (age at menarche), even as on-average values rose (BMI, WC), idled (childhood height) and fell (SBP, serum cholesterol, age at menarche), with patterns often varying by race/ethnicity and socioeconomic measure; similar results occurred for relative inequities. For example, for WC, the adverse 20th (low) vs 80th (high) income percentile gap increased only among Whites (NHES I: 0.71 cm [95% confidence interval (CI) -0.74, 2.16); NHANES 2005-08: 2.10 (95% CI 0.96, 3.62)]. By contrast, age at menarche for girls in the 20th vs 80th income percentile among Black girls remained consistently lower, by 0.34 years (95% CI 0.12, 0.55) whereas among White girls the initial null difference became inverse [NHANES 2005-08: -0.49 years (95% CI -0.86, -0.12; overall P = 0.0015)]. Adjusting for socioeconomic position only modestly altered Black/White health inequities. CONCLUSIONS: Health inequities need not rise as population health improves.

History, haldanes and health inequities: exploring phenotypic changes in body size by generation and income level in the US-born White and Black non-Hispanic populations 1959-1962 to 2005-2008.

BACKGROUND: Most public health literature on trends in population health and health inequities pertains to observed or targeted changes in rates or proportions per year or decade. We explore, in novel analyses, whether additional insight can be gained by using the 'haldane', a metric developed by evolutionary biologists to measure change in traits in standard deviations per generation, thereby enabling meaningful comparisons across species and time periods. METHODS: We analysed the phenotypic embodied traits of body height, weight and body mass index of US-born White and Black non-Hispanic adults ages 20 to 44 as measured in six large nationally representative population samples spanning from the 1959-1962 National Health Examination Survey I to the 2005-2008 National Health and Nutrition Examination Survey. Setting the former as baseline, we computed the haldane for each outcome for each racial/ethnic group for each survey, overall and stratified by family income quintile. RESULTS: For height, high rates of phenotypic change (haldane ≥ 0.3) occurred chiefly between 1960 and 1980, especially for the Black population in the higher income quintiles. By contrast, for weight, high rates of phenotypic change became evident for both the White and Black populations in the late 1980s and increased thereafter; for body mass index, the shift to high rates of change started in both groups in the late 1990s, especially in the middle income quintiles. CONCLUSIONS: Our results support use of the haldane as a supplemental metric to place changes in population health and health inequities in a larger biological and historical context.

Not just smoking and high-tech medicine: socioeconomic inequities in U.S. mortality rates, overall and by race/ethnicity, 1960-2006.

Recent research on the post-1980 widening of U.S. socioeconomic inequalities in mortality has emphasized the contribution of smoking and high-tech medicine, with some studies treating the growing inequalities as effectively inevitable. No studies, however, have analyzed long-term trends in U.S. mortality rates and inequities unrelated to smoking or due to lack of basic medical care, even as a handful have shown that U.S. socioeconomic inequalities in overall mortality shrank between the mid-1960s and 1980. The authors accordingly analyzed U.S. mortality data for 1960-2006, stratified by county income quintile and race/ethnicity, for mortality unrelated to smoking and preventable by 1960s' standards of medical care. Key findings are that relative and absolute socioeconomic inequalities in U.S. mortality unrelated to smoking and preventable by 1960s' medical care standards shrank between the 1960s and 1980 and then increased and stagnated, with absolute rates on a par with several leading causes of death, and with the burden greatest for U.S. populations of color. None of these findings can be attributed to trends in smoking-related deaths and access to high-tech medicine, and they also demonstrate that socioeconomic inequities in mortality can shrink and need not inevitably rise.

Shrinking, widening, reversing, and stagnating trends in US socioeconomic inequities in cancer mortality for the total, black, and white populations: 1960-2006.

OBJECTIVES OF STUDY: To test recent claims that cancer inequities are bound to increase as population health improves. METHODS: We analyzed 1960-2006 age-standardized US county cancer mortality data, total and site-specific (lung, prostate, colorectal, breast, cervix, stomach), stratified by county income quintile for the US total, black, and white populations. RESULTS: Between 1960 and 2006, US socioeconomic inequities in cancer mortality variously shrunk, widened, reversed, and stagnated, depending on time period and cancer site. For all cancers combined and most, but not all, sites, absolute, but not relative, socioeconomic gaps were greater for the black compared to white population. Compared to the yearly age-specific mortality rates among whites in the most affluent counties, the percent of excess cancer deaths among whites in the lower four county income quintiles first rose above 0 in 1990 and in 2006 equaled 5.4% (95% CI 4.8, 6.0); among blacks, it rose from 6.0% (95% CI 4.5, 7.4) in 1960 to 24.7% (95% CI 23.9, 25.5) in 1990 and remained at this level through 2006. CONCLUSIONS: The hypothesis that cancer mortality inequities are bound to increase is refuted by long-term data on total and site-specific cancer mortality stratified by socioeconomic position and race/ethnicity.

Exposing racial discrimination: implicit & explicit measures--the My Body, My Story study of 1005 US-born black & white community health center members.

BACKGROUND: To date, research on racial discrimination and health typically has employed explicit self-report measures, despite their potentially being affected by what people are able and willing to say. We accordingly employed an Implicit Association Test (IAT) for racial discrimination, first developed and used in two recent published studies, and measured associations of the explicit and implicit discrimination measures with each other, socioeconomic and psychosocial variables, and smoking. METHODOLOGY/PRINCIPAL FINDINGS: Among the 504 black and 501 white US-born participants, age 35-64, randomly recruited in 2008-2010 from 4 community health centers in Boston, MA, black participants were over 1.5 times more likely (p<0.05) to be worse off economically (e.g., for poverty and low education) and have higher social desirability scores (43.8 vs. 28.2); their explicit discrimination exposure was also 2.5 to 3.7 times higher (p<0.05) depending on the measure used, with over 60% reporting exposure in 3 or more domains and within the last year. Higher IAT scores for target vs. perpetrator of discrimination occurred for the black versus white participants: for "black person vs. white person": 0.26 vs. 0.13; and for "me vs. them": 0.24 vs. 0.19. In both groups, only low non-significant correlations existed between the implicit and explicit discrimination measures; social desirability was significantly associated with the explicit but not implicit measures. Although neither the explicit nor implicit discrimination measures were associated with odds of being a current smoker, the excess risk for black participants (controlling for age and gender) rose in models that also controlled for the racial discrimination and psychosocial variables; additional control for socioeconomic position sharply reduced and rendered the association null. CONCLUSIONS: Implicit and explicit measures of racial discrimination are not equivalent and both warrant use in research on racial discrimination and health, along with data on socioeconomic position and social desirability.

Racial discrimination, psychological distress, and self-rated health among US-born and foreign-born Black Americans.

OBJECTIVES: We investigated associations among racial discrimination, psychological distress, and self-rated health among US-born and immigrant Black Americans. METHODS: We conducted a cross-sectional analysis of a cohort of employed working-class Black Americans (193 US-born, 275 foreign-born). RESULTS: Both US-born and foreign-born Black participants had high levels of exposure to poverty (51% and 57%, respectively) and racial discrimination (76% and 60%) and reported high levels of severe psychological distress (14% and 16% had a Kessler 6 [K6] score of 13 or greater); 17% and 7% reported fair or poor health. After controlling for relevant covariates, their risk parameters for racial discrimination (high vs no exposure) were 4.0 (95% confidence interval [CI] = 2.3, 5.6) and 3.3 (95% CI = 2.1, 4.5), respectively, for continuous K6 score; corresponding odds ratios for severe psychological distress were 6.9 (95% CI = 1.4, 35.7) and 6.8 (95% CI = 2.5, 18.3). No associations existed between racial discrimination and self-reported health, suggesting that an underlying propensity to report adversity does not account for our psychological distress findings. CONCLUSIONS: Our results attest to the salience of racial discrimination, nativity, and socioeconomic position in understanding the experiences and psychological health of Black Americans.

Occupational, social, and relationship hazards and psychological distress among low-income workers: implications of the 'inverse hazard law'.

BACKGROUND: Few studies have simultaneously included exposure information on occupational hazards, relationship hazards (eg, intimate partner violence) and social hazards (eg, poverty and racial discrimination), especially among low-income multiracial/ethnic populations. METHODS: A cross-sectional study (2003-2004) of 1202 workers employed at 14 worksites in the greater Boston area of Massachusetts investigated the independent and joint association of occupational, social and relationship hazards with psychological distress (K6 scale). RESULTS: Among this low-income cohort (45% were below the US poverty line), exposure to occupational, social and relationship hazards, per the 'inverse hazard law,' was high: 82% exposed to at least one occupational hazard, 79% to at least one social hazard, and 32% of men and 34% of women, respectively, stated they had been the perpetrator or target of intimate partner violence (IPV). Fully 15.4% had clinically significant psychological distress scores (K6 score ≥ 13). All three types of hazards, and also poverty, were independently associated with increased risk of psychological distress. In models including all three hazards, however, significant associations with psychological distress occurred among men and women for workplace abuse and high exposure to racial discrimination only; among men, for IPV; and among women, for high exposure to occupational hazards, poverty and smoking. CONCLUSIONS: Reckoning with the joint and embodied reality of diverse types of hazards involving how people live and work is necessary for understanding determinants of health status.