Hair relaxer use and risk of uterine cancer in the Black Women's Health Study.

BACKGROUND: Chemical hair relaxers, use of which is highly prevalent among Black women in the US, have been inconsistently linked to risk of estrogen-dependent cancers, such as breast cancer, and other reproductive health conditions. Whether hair relaxer use increases risk of uterine cancer is unknown. METHODS: In the Black Women's Health Study, 44,798 women with an intact uterus who self-identified as Black were followed from 1997, when chemical hair relaxer use was queried, until 2019. Over follow-up, 347 incident uterine cancers were diagnosed. We used multivariable Cox proportional hazards regression models, adjusted for age and other potential confounders, to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations of hair relaxer use with risk of uterine cancer. RESULTS: Compared to women who never used hair relaxers or used them infrequently (<4 years and ≤1-2 times/year), the HR for uterine cancer associated with heavy use (≥15 years and at least 5 times/year) was 1.18 (95% CI: 0.81, 1.71). However, among postmenopausal women, compared to never/light use, the HR for moderate use was 1.60 (95% CI: 1.01, 2.53), the HR for heavy use was 1.64 (1.01, 2.64), and the HR for ≥20 years of use regardless of frequency was 1.71 (1.08, 2.72). Results among premenopausal women were null. CONCLUSIONS: In this large cohort of Black women, long-term use of chemical hair relaxers was associated with increased risk of uterine cancer among postmenopausal women, but not among premenopausal women. These findings suggest that hair relaxer use may be a potentially modifiable risk factor for uterine cancer.

Perceived racism associated with declines in self-rated oral health among U.S. Black women.

PURPOSE: Racial disparities in oral health are well-documented. Stress has been associated with both perceived racism and oral health, yet little research has directly investigated the association between perceived racism and oral health. METHODS: We used data from the Black Women's Health Study, a longitudinal cohort study that includes a geographically diverse sample of Black women across the United States. Perceived exposure to racism was assessed via two scales, one assessing lifetime exposure and one everyday exposure. Self-rated oral health was subsequently assessed over multiple time points. We used Cox proportional hazard models to calculate adjusted incidence rate ratios estimating the association between higher levels of perceived racism and incident "fair" or "poor" oral health, and explored potential effect measure modification using stratified models. RESULTS: The adjusted incidence rate ratios (n = 27,008) relating perceived racism to incident fair or poor oral health were 1.50 (95% confidence interval 1.35, 1.66) comparing the highest quartile of everyday racism to the lowest and 1.45 (95% confidence interval 1.31, 1.61) for the highest score of lifetime racism compared to the lowest. We did not see evidence of effect modification. CONCLUSIONS: Higher levels of perceived racism documented in 2009 were associated with declines in self-rated oral health from 2011 to 2019.

Neighborhood disadvantage and lung cancer risk in a national cohort of never smoking Black women.

BACKGROUND: Compared to women of other races who have never smoked, Black women have a higher risk of lung cancer. Whether neighborhood disadvantage, which Black women experience at higher rates than other women, is linked to never-smoking lung cancer risk remains unclear. This study investigates the association of neighborhood disadvantage and lung cancer risk in Black never-smoking women. METHODS AND MATERIALS: This research utilized data from the Black Women's Health Study, a prospective cohort of 59,000 Black women recruited from across the US in 1995 and followed by biennial questionnaires. Associations of lung cancer incidence with neighborhood-level factors (including two composite variables derived from Census Bureau data: neighborhood socioeconomic status and neighborhood concentrated disadvantage), secondhand smoke exposure, and PM2.5 were estimated using Fine-Gray subdistribution hazard models. RESULTS: Among 37,650 never-smokers, 77 were diagnosed with lung cancer during follow-up from 1995 to 2018. The adjusted subdistribution hazard ratio (sHR) of lung cancer incidence with ten unit increase in neighborhood concentrated disadvantage index was 1.30 (95 % CI: 1.04, 1.63, p = 0.023). Exposure to secondhand smoke at work was associated with increased risk (sHR = 1.93, 95 % CI: 1.21, 3.10, p = 0.006), but exposure to secondhand smoke at home and PM2.5 was not. CONCLUSION: Worse neighborhood concentrated disadvantage was associated with increased lung cancer risk in Black women who never smoked. These findings suggest that non-tobacco-related factors in disadvantaged neighborhoods may be linked to lung cancer risk in Black women and that these factors must be understood and targeted to achieve health equity.

Hair product use and breast cancer incidence in the Black Women's Health Study.

Hair relaxers and leave-in conditioners and oils, commonly used by Black/African American women, may contain estrogens or estrogen-disrupting compounds. Thus, their use may contribute to breast cancer risk. Results of the few previous studies on this topic are inconsistent. We assessed the relation of hair relaxer and leave-in conditioner use to breast cancer incidence in the Black Women's Health Study, a nationwide prospective study of Black women. Among 50 543 women followed from 1997 to 2017, 2311 incident breast cancers occurred. Multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazards regression for breast cancer overall and by estrogen receptor (ER) status. For heavy use (≥15 years of use for ≥7 times/year) of hair relaxers relative to never/light use (<4 years, no more than 1-2 times/year), the multivariable HR for breast cancer overall was 1.13 (95%CI: 0.96-1.33). Duration, frequency, age at first use and number of scalp burns were not associated with overall breast cancer risk. For heavy use of hair relaxers containing lye, the corresponding HR for ER+ breast cancer was 1.32 (95% CI: 0.97, 1.80); there was no association for non-lye products. There was no association of conditioner use and breast cancer. Results of this study were largely null, but there was some evidence that heavy use of lye-containing hair relaxers may be associated with increased risk of ER+ breast cancer. Consistent results from several studies are needed before it can be concluded that use of certain hair relaxers impacts breast cancer development.

A prospective cohort study of ambient air pollution exposure and risk of uterine leiomyomata.

STUDY QUESTION: To what extent are ambient concentrations of particulate matter <2.5 microns (PM2.5), nitrogen dioxide (NO2) and ozone (O3) associated with risk of self-reported physician-diagnosed uterine leiomyomata (UL)? SUMMARY ANSWER: In this large prospective cohort study of Black women, ambient concentrations of O3, but not PM2.5 or NO2, were associated with increased risk of UL. WHAT IS KNOWN ALREADY: UL are benign tumors of the myometrium that are the leading cause of gynecologic inpatient care among reproductive-aged women. Black women are clinically diagnosed at two to three times the rate of white women and tend to exhibit earlier onset and more severe disease. Two epidemiologic studies have found positive associations between air pollution exposure and UL risk, but neither included large numbers of Black women. STUDY DESIGN, SIZE, DURATION: We conducted a prospective cohort study of 21 998 premenopausal Black women residing in 56 US metropolitan areas from 1997 to 2011. PARTICIPANTS/MATERIAL, SETTING, METHODS: Women reported incident UL diagnosis and method of confirmation (i.e. ultrasound, surgery) on biennial follow-up questionnaires. We modeled annual residential concentrations of PM2.5, NO2 and O3 throughout the study period. We used Cox proportional hazards regression models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for a one-interquartile range (IQR) increase in air pollutant concentrations, adjusting for confounders and co-pollutants. MAIN RESULTS AND THE ROLE OF CHANCE: During 196 685 person-years of follow-up, 6238 participants (28.4%) reported physician-diagnosed UL confirmed by ultrasound or surgery. Although concentrations of PM2.5 and NO2 were not appreciably associated with UL (HRs for a one-IQR increase: 1.01 (95% CI: 0.93, 1.10) and 1.05 (95% CI: 0.95, 1.16), respectively), O3 concentrations were associated with increased UL risk (HR for a one-IQR increase: 1.19, 95% CI: 1.07, 1.32). The association was stronger among women age <35 years (HR: 1.26, 95% CI: 0.98, 1.62) and parous women (HR: 1.28, 95% CI: 1.11, 1.48). LIMITATIONS, REASONS FOR CAUTION: Our measurement of air pollution is subject to misclassification, as monitoring data are not equally spatially distributed and we did not account for time-activity patterns. Our outcome measure was based on self-report of a physician diagnosis, likely resulting in under-ascertainment of UL. Although we controlled for several individual- and neighborhood-level confounding variables, residual confounding remains a possibility. WIDER IMPLICATIONS OF THE FINDINGS: Inequitable burden of air pollution exposure has important implications for racial health disparities, and may be related to disparities in UL. Our results emphasize the need for additional research focused on environmental causes of UL. STUDY FUNDING/COMPETING INTEREST(S): This research was funded by the National Cancer Institute (U01-CAA164974) and the National Institute of Environmental Health Sciences (R01-ES019573). L.A.W. is a fibroid consultant for AbbVie, Inc. and accepts in-kind donations from Swiss Precision Diagnostics, Sandstone Diagnostics, FertilityFriend.com and Kindara.com for primary data collection in Pregnancy Study Online (PRESTO). M.J. declares consultancy fees from the Health Effects Institute (as a member of the review committee). The remaining authors declare they have no actual or potential competing financial interests. TRIAL REGISTRATION NUMBER: N/A.

Air pollution and breast cancer risk in the Black Women's Health Study.

BACKGROUND: Air pollution contains numerous carcinogens and endocrine disruptors which may be relevant for breast cancer. Previous research has predominantly been conducted in White women; however, Black women may have higher air pollution exposure due to geographic and residential factors. OBJECTIVE: We evaluated the association between air pollution and breast cancer risk in a large prospective population of Black women. METHODS: We estimated annual average ambient levels of particulate matter <2.5 µm (PM2.5), nitrogen dioxide (NO2) and ozone (O3) at the 1995 residence of 41,317 participants in the Black Women's Health Study who resided in 56 metropolitan areas across the United States. Cox proportional hazards regression was used to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for an interquartile range (IQR) increase in each pollutant. We evaluated whether the association varied by menopausal status, estrogen receptor (ER) status of the tumor and geographic region of residence. RESULTS: With follow-up through 2015 (mean = 18.3 years), 2146 incident cases of breast cancer were confirmed. Higher exposure to NO2 or O3 was not associated with a higher risk of breast cancer. For PM2.5, although we observed no association overall, there was evidence of modification by geographic region for both ER- (p for heterogeneity = 0.01) and premenopausal breast cancer (p for heterogeneity = 0.01). Among women living in the Midwest, an IQR increase in PM2.5 (2.87 µg/m3), was associated with a higher risk of ER- (HR = 1.53, 95% CI: 1.07-2.19) and premenopausal breast cancer (HR = 1.32, 95% CI: 1.03-1.71). In contrast, among women living in the South, PM2.5 was inversely associated with both ER- (HR = 0.74, 95% CI: 0.56-0.97) and premenopausal breast cancer risk (HR = 0.75, 95% CI: 0.62-0.91). DISCUSSION: Overall, we observed no association between air pollution and increased breast cancer risk among Black women, except perhaps among women living in the Midwestern US.

Aspirin use and risk of breast cancer in African American women.

BACKGROUND: Use of aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) has been hypothesized to be associated with reduced risk of breast cancer; however, results of epidemiological studies have been mixed. Few studies have investigated these associations among African American women. METHODS: To assess the relation of aspirin use to risk of breast cancer in African American women, we conducted a prospective analysis within the Black Women's Health Study, an ongoing nationwide cohort study of 59,000 African American women. On baseline and follow-up questionnaires, women reported regular use of aspirin (defined as use at least 3 days per week) and years of use. During follow-up from 1995 through 2017, 1919 invasive breast cancers occurred, including 1112 ER+, 569 ER-, and 284 triple-negative (TN) tumors. We used age-stratified Cox proportional hazards regression models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations of aspirin use with risk of ER+, ER-, and TN breast cancer, adjusted for established breast cancer risk factors. RESULTS: Overall, the HR for current regular use of aspirin relative to non-use was 0.92 (95% CI 0.81, 1.04). For ER+, ER-, and TN breast cancer, corresponding HRs were 0.98 (0.84, 1.15), 0.81 (0.64, 1.04), and 0.70 (0.49, 0.99), respectively. CONCLUSIONS: Our findings with regard to ER- and TN breast cancer are consistent with hypothesized inflammatory mechanisms of ER- and TN breast cancer, rather than hormone-dependent pathways. Aspirin may represent a potential opportunity for chemoprevention of ER- and TN breast cancer.

Experiences of racism and subjective cognitive function in African American women.

INTRODUCTION: We hypothesized that frequent experiences of racism among African American women would adversely affect subjective cognitive function (SCF), based on the established association of psychological stress with memory decline. METHODS: We used multinomial logistic regression to quantify the association between experiences of racism and SCF, based on six questions, among 17,320 participants in the prospective Black Women's Health Study. RESULTS: The multivariable odds ratio (OR, 95% confidence interval [CI]) for poor compared to good SCF among women at the highest versus the lowest level of daily racism (eg, poorer service in stores) was 2.75 (2.34 to 3.23); for the same comparison among women at the highest level of institutional racism (eg, discriminated against in housing) relative to the lowest, the OR was 2.66 (2.24 to 3.15). The associations were mediated, in part, by depression and insomnia. DISCUSSION: Experiences of racism, a highly prevalent psychosocial stressor among African Americans, were associated with lower SCF.

Association of type 2 diabetes with central-scalp hair loss in a large cohort study of African American women.

BACKGROUND: Hair loss on the central scalp commonly occurs among African American (AA) women and can pose substantial psychosocial burdens. The causes of hair loss remain obscure, although type 2 diabetes has been hypothesized to increase the risk of hair loss. The objective of the present study was to prospectively estimate the association between type 2 diabetes and severe central hair loss in AA women. METHODS: The Black Women's Health Study has collected data on medical and lifestyle factors, including diagnosis of type 2 diabetes, biennially since 1995 from AA women across the United States. The present analysis was based on responses from 5389 women to an online hair loss questionnaire in 2015. Respondents indicated severity of central hair loss on a validated six-item photographic scale; the highest levels, levels 3 to 5, were designated as severe. We used Cox proportional hazards models to estimate multivariable hazard ratios and 95% confidence intervals (CIs) for type 2 diabetes in relation to severe central hair loss. RESULTS: During the follow-up period, 850 cases of severe hair loss occurred. The multivariable hazard ratio for severe hair loss associated with diabetes was 1.68 (95% CI, 1.38-2.06) overall, and 2.05 (95% CI, 1.48-2.85) for diabetes duration of ≥ 10 years. CONCLUSION: Type 2 diabetes was associated with an increased risk of severe central scalp hair loss in AA women. Patients with type 2 diabetes should be followed closely for central scalp hair loss so that appropriate treatment can be offered.

Ambient ozone and incident diabetes: A prospective analysis in a large cohort of African American women.

BACKGROUND: Ozone is a ubiquitous air pollutant with increasing concentrations in many populous regions. Toxicological studies show that ozone can cause oxidative stress and increase insulin resistance. These pathways may contribute to metabolic changes and diabetes formation. In this paper, we investigate the association between ozone and incident type 2 diabetes in a large cohort of African American women. METHODS: We used Cox proportional hazards models to calculate hazard ratios (HRs) for incident type 2 diabetes associated with exposure to ozone in a cohort of 45,231 African American women living in 56 metropolitan areas across the United States. Ozone levels were estimated using the U.S. EPA Models-3/Community Multiscale Air Quality (CMAQ) predictions fused with ground measurements at a resolution of 12km for the years 2007-2008. RESULTS: The HR per interquartile range increment of 6.7ppb of ozone was 1.18 (95% CI 1.04-1.34) for incident diabetes in adjusted models. This association was unaltered in models that controlled for fine particulate matter with diameter <2.5µm (PM2.5). Associations were modified by nitrogen dioxide (NO2) levels, such that HRs for ozone levels were larger in areas of lower NO2. CONCLUSIONS: Our results provide initial evidence of a positive association between O3 and incident diabetes in African American women. Given the ubiquity of ozone exposure and the importance of diabetes on quality of life and survival, these results may have important implications for the protection of public health.

Long-Term Exposure to NO2 and Ozone and Hypertension Incidence in the Black Women's Health Study.

BACKGROUND: Evidence shows that exposure to air pollutants can increase blood pressure in the short and long term. Some studies show higher levels of hypertension prevalence in areas of high pollution. Few data exist on the association of air pollution with hypertension incidence. The purpose of the present study was to prospectively assess the associations of the traffic-related nitrogen dioxide (NO2) and of ozone with the incidence of hypertension in the Black Women's Health Study (BWHS), a large cohort study of African American women. METHODS: We used Cox proportional hazards models to calculate hazard ratios (HRs) and 95% confidence intervals (CI) for hypertension associated with exposure to NO2 and ozone among 33,771 BWHS participants. NO2 and ozone levels at participant residential locations were estimated with validated models. RESULTS: From 1995 to 2011, 9,570 incident cases of hypertension occurred in a total of 348,154 person-years (median follow-up time, 11 years). The multivariable HRs per interquartile range of NO2 (9.7 ppb) and ozone (6.7 ppb) were 0.92 (95% CI = 0.86, 0.98) and 1.09 (95% CI = 1.00, 1.18). CONCLUSIONS: In this large cohort of African American women, higher ozone levels were associated with an increase in hypertension incidence. Higher NO2 levels were not associated with greater hypertension incidence; indeed, incidence was lower at higher NO2 levels.

Comparing the Health Effects of Ambient Particulate Matter Estimated Using Ground-Based versus Remote Sensing Exposure Estimates.

BACKGROUND: Remote sensing (RS) is increasingly used for exposure assessment in epidemiological and burden of disease studies, including those investigating whether chronic exposure to ambient fine particulate matter (PM2.5) is associated with mortality. OBJECTIVES: We compared relative risk estimates of mortality from diseases of the circulatory system for PM2.5 modeled from RS with that for PM2.5 modeled using ground-level information. METHODS: We geocoded the baseline residence of 668,629 American Cancer Society Cancer Prevention Study II (CPS-II) cohort participants followed from 1982 to 2004 and assigned PM2.5 levels to all participants using seven different exposure models. Most of the exposure models were averaged for the years 2002-2004, and one RS estimate was for a longer, contemporaneous period. We used Cox proportional hazards regression to estimate relative risks (RRs) for the association of PM2.5 with circulatory mortality and ischemic heart disease. RESULTS: Estimates of mortality risk differed among exposure models. The smallest relative risk was observed for the RS estimates that excluded ground-based monitors for circulatory deaths [RR = 1.02, 95% confidence interval (CI): 1.00, 1.04 per 10 µg/m3 increment in PM2.5]. The largest relative risk was observed for the land-use regression model that included traffic information (RR = 1.14, 95% CI: 1.11, 1.17 per 10 µg/m3 increment in PM2.5). CONCLUSIONS: We found significant associations between PM2.5 and mortality in every model; however, relative risks estimated from exposure models using ground-based information were generally larger than those estimated using RS alone.

Long term exposure to NO2 and diabetes incidence in the Black Women's Health Study.

While laboratory studies show that air pollutants can potentiate insulin resistance, the epidemiologic evidence regarding the association of air pollution with diabetes incidence is conflicting. The purpose of the present study was to assess the association of the traffic-related nitrogen dioxide (NO2) with the incidence of diabetes in a longitudinal cohort study of African American women. We used Cox proportional hazards models to calculate hazard ratios and 95% confidence intervals (CI) for diabetes associated with exposure to NO2 among 43,003 participants in the Black Women's Health Study (BWHS). Pollutant levels at participant residential locations were estimated with 1) a land use regression model for participants living in 56 metropolitan areas, and 2) a dispersion model for participants living in 27 of the cities. From 1995 to 2011, 4387 cases of diabetes occurred. The hazard ratios per interquartile range of NO2 (9.7 ppb), adjusted for age, metropolitan area, education, vigorous exercise, body mass index, smoking, and diet, were 0.96 (95% CI 0.88-1.06) using the land use regression model estimates and 0.94 (95% CI 0.80, 1.10) using the dispersion model estimates. The present results do not support the hypothesis that exposure to NO2 contributes to diabetes incidence in African American women.

Ambient Air Pollution and 16-Year Weight Change in African-American Women.

INTRODUCTION: Substantial research has been dedicated to understanding the reasons for the dramatic rise in obesity rates in the U.S. in the last 2 decades. Animal studies and epidemiologic studies in children have suggested that air pollution might contribute to weight gain. This study investigates the association between ambient air pollution and weight gain over 16 years of follow-up (1995-2011) in a large cohort of African-American women in the U.S. METHODS: This study assessed associations of fine particulate matter, ozone, and nitrogen dioxide with weight gain using a linear random effects model. All analyses were conducted in 2015. RESULTS: There was no statistically significant association between weight change and fine particulate matter (mean weight change over 16 years per interquartile range [2.9 µg/m(3)], 0.12 kg; 95% CI=-0.10, 0.35) and ozone (0.16 kg per interquartile range [6.7 ppb]; 95% CI=-0.11, 0.43). There was a small decrease in weight associated with nitrogen dioxide (-0.50 per interquartile range [9.7 ppb]; 95% CI=-0.77, -0.23). CONCLUSIONS: The results do not provide support for an association of air pollution with weight gain in African-American adult women.

Neighborhood Socioeconomic Status in Relation to Serum Biomarkers in the Black Women's Health Study.

Lower neighborhood socioeconomic status (SES) is associated with higher cardiovascular disease (CVD) risk. Black women have a higher CVD risk and are more likely to live in poor neighborhoods than white women. We examined the association of neighborhood SES with several CVD biomarkers using data from the Black Women's Health Study (BWHS), a follow-up study of US black women reporting high levels of education and income. Blood specimens of 418 BWHS participants were assayed for C-reactive protein (CRP), hemoglobin A1C (hgA1C), and high-density lipoprotein (HDL) cholesterol. US Census block group data were linked to the women's addresses to reflect neighborhood SES. Multivariable-adjusted mixed linear regression models that adjusted for person-level SES and for cardiovascular risk factors were used to assess CRP, hgA1C, and HDL levels in relation to quintiles of neighborhood SES. Women living in the poorest neighborhoods had the least favorable biomarker levels. As neighborhood SES increased, CRP decreased (P for trend = 0.01), hgA1C decreased (P for trend = 0.07), and HDL increased (P for trend = 0.19). These associations were present within strata of individual educational level. The present findings suggest that neighborhood environments may affect physiological processes within residents independently of individual SES.

Neighborhood and Individual Socioeconomic Status and Asthma Incidence in African American Women.

OBJECTIVE: Individual socioeconomic status (SES) has been associated with asthma incidence but whether neighborhood SES has an influence is unknown. We assessed the contributions of neighborhood socioeconomic status (SES), neighborhood housing density, neighborhood racial composition, and individual SES to the development of adult-onset asthma in Black women, accounting for other known or suspected risk factors. DESIGN AND PARTICIPANTS: Prospective cohort study conducted among 47,779 African American women followed with biennial health questionnaires from 1995 to 2011. METHODS AND MAIN OUTCOME MEASURES: Incident asthma was defined as new self-report of doctor-diagnosed asthma with concurrent use of asthma medication. We assessed neighborhood SES, indicated by census variables representing income, education, and wealth, and housing density and % African American population, as well as individual SES, indicated by highest education of participant/spouse. Cox proportional hazards models were used to derive multivariable hazard ratios (HRs) and 95% CIs for the association of individual SES and neighborhood variables with asthma incidence. RESULTS: During a 16-year follow-up period, 1520 women reported incident asthma. Neighborhood factors were not associated with asthma incidence after control for individual SES, body mass index, and other factors. Compared with college graduates, the multivariable HR for asthma was 1.13 (95% CI 1.00-1.28) for women with some college education and 1.23 (95% CI 1.05-1.44) for women with no more than a high school education. CONCLUSIONS: Individual SES, but not neighborhood SES or other neighborhood factors, was associated with the incidence of adult-onset asthma in this population of African American women.

Temporal aspects of air pollutant measures in epidemiologic analysis: a simulation study.

Numerous observational studies have assessed the association between ambient air pollution and chronic disease incidence, but there is no uniform approach to create an exposure metric that captures the variability in air pollution through time and determines the most relevant exposure window. The purpose of the present study was to assess ways of modeling exposure to air pollution in relation to incident hypertension. We simulated data on incident hypertension to assess the performance of six air pollution exposure metrics, using characteristics from the Black Women's Health Study. Each metric made different assumptions about how to incorporate time trends in pollutant data, and the most relevant window of exposure. We use observed values for particulate matter ≤ 2.5 microns (PM2.5) for this cohort to create the six exposure metrics and fit Cox proportional hazards models to the simulated data using the six metrics. The optimal exposure metric depends on the underlying association between PM2.5 and disease, which is unknown. Metrics that incorporate exposure information from multiple years tend to be more robust and suffer from less bias. This study provides insight into factors that influence the metric used to quantifying exposure to PM2.5 and suggests the need for careful sensitivity analyses.

PM2.5 and Diabetes and Hypertension Incidence in the Black Women's Health Study.

BACKGROUND: Clinical studies have shown that exposure to fine particulate matter (PM2.5) can increase insulin resistance and blood pressure. The epidemiologic evidence for an association of PM2.5 exposure with the incidence of type 2 diabetes or hypertension is inconsistent. Even a modest association would have great public health importance given the ubiquity of exposure and high prevalence of the conditions. METHODS: We used Cox proportional hazards models to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for incident type 2 diabetes and hypertension associated with exposure to PM2.5 in a large cohort of African American women living in 56 metropolitan areas across the US, using data from the Black Women's Health Study. Pollutant levels were estimated at all residential locations over follow-up with a hybrid model incorporating land use regression and Bayesian Maximum Entropy techniques. RESULTS: During 1995 to 2011, 4,387 cases of diabetes and 9,570 cases of hypertension occurred. In models controlling for age, questionnaire cycle, and metro area, there were positive associations with diabetes (HR = 1.13, 95% CI = 1.04, 1.24) and hypertension (HR = 1.06, 95% CI = 1.00, 1.12) per interquartile range of PM2.5 (2.9 µg/m). Multivariable HRs, however, were 0.99 (95% CI = 0.90, 1.09) for diabetes and 0.99 (95% CI = 0.93, 1.06) for hypertension. CONCLUSIONS: Our results provide little support for an association of PM2.5 with diabetes or hypertension incidence.

Obesity and weight gain in relation to incidence of sarcoidosis in US black women: data from the Black Women's Health Study.

BACKGROUND: Sarcoidosis, a systemic disorder characterized by chronic granulomatous inflammation, occurs more frequently among US black women, as do overweight and obesity. Little is known about the relation of overweight and obesity, which induce chronic inflammation, to incidence of sarcoidosis. METHODS: We assessed the relation of obesity and weight gain to the incidence of sarcoidosis in the Black Women's Health Study, a follow-up study of 59,000 US black women aged 21 to 69 years at baseline in 1995. Information on weight at age 18 years, height, current weight, incident sarcoidosis, and covariates was collected at baseline and on biennial follow-up questionnaires. Cox regression models adjusted for age, education, geographic region, smoking, alcohol consumption, and physical activity were used to estimate incidence rate ratios (IRRs) and 95% CIs. RESULTS: From 1995 through 2011, 454 incident cases of sarcoidosis occurred during 707,557 person-years of follow-up. The incidence of sarcoidosis increased with increasing BMI and weight gain. The IRR was 1.40 (95% CI, 0.88-2.25) for BMI ≥ 30 kg/m2 at age 18 years relative to 20 to 24 kg/m2 (P trend = .18), 1.42 (95% CI, 1.07-1.89) for BMI ≥ 35 kg/m2 at baseline relative to 20 to 24 kg/m2 (P trend = .01), and 1.47 (95% CI, 1.10-1.97) for a weight gain between age 18 years and baseline of ≥ 30 kg relative to 0 to 9 kg (P trend = .16). In stratified analyses, there were significant trends of sarcoidosis incidence with increasing BMI and weight gain in women aged ≥ 45 years and ever smokers. CONCLUSIONS: The present study provides evidence that weight gain and obesity during adulthood are associated with increased sarcoidosis incidence.

Active and passive smoking and the incidence of asthma in the Black Women's Health Study.

RATIONALE: Evidence linking active or passive smoking to the incidence of adult-onset asthma is inconsistent with both positive and inverse associations being reported. Most previous studies of active smoking have not accounted for passive smoke exposure, which may have introduced bias. OBJECTIVES: To assess the separate associations of active and passive smoking to the incidence of adult-onset asthma in the U.S. Black Women's Health Study, a prospective cohort of African American women followed since 1995 with mailed biennial questionnaires. METHODS: Active smoking status was reported at baseline and updated on all follow-up questionnaires. Passive smoke exposure during childhood, adolescence, and adulthood was ascertained in 1997. Asthma cases comprised women who reported doctor-diagnosed asthma with concurrent asthma medication use. Cox regression models were used to derive multivariable hazard ratios (HRs) and 95% confidence intervals (CIs) for former and current smoking and for passive smoking among nonsmokers compared with a reference category of never active or passive smokers. MEASUREMENTS AND MAIN RESULTS: Among 46,182 participants followed from 1995 to 2011, 1,523 reported incident asthma. The multivariable HRs for former active smoking, current active smoking, and passive smoking only were, respectively, 1.36 (95% CI, 1.11-1.67), 1.43 (95% CI, 1.15-1.77), and 1.21 (95% CI, 1.00-1.45), compared with never active/passive smoking. CONCLUSIONS: In this large population with 16 years of follow-up, active smoking increased the incidence of adult-onset asthma, and passive smoke exposure increased the risk among nonsmokers. Continued efforts to reduce exposure to tobacco smoke may have a beneficial effect on the incidence of adult-onset asthma.