Girls' Sleep Trajectories Across the Pubertal Transition: Emerging Racial/Ethnic Differences.

PURPOSE: This study aims to examine the longitudinal association between puberty and sleep in a diverse sample of girls and explore racial/ethnic differences in this association. METHODS: Using latent growth curve modeling, the present study measured pubertal development (timing and rate) and sleep (wake time and bedtime) in 1,239 socioeconomically and ethnically diverse girls starting when they were 6-8 years old and followed longitudinally for up to 8 years. Pubertal assessment was conducted annually in clinic by physical examination, classified by sexual maturation stage for breast and pubic hair development by trained raters. RESULTS: In line with previous research, black girls had the earliest pubertal development, followed by Hispanic, white, and Asian girls. Black girls, on average, reported significantly shorter sleep duration than Hispanic (ß = -.20, p < .001), Asian (ß = -.29, p = .002), and white (ß = -.35, p < .001) girls. In a series of dual-process models, we found that early pubertal timing predicted shorter sleep duration for early-maturing black girls (breast development: ß = .13, p = .005; pubic hair development: ß = .14, p = .012). There was no evidence of any association between pubertal rate and sleep. All models controlled for family socioeconomic status and body mass index. CONCLUSION: Sleep is essential for many aspects of youth development, including emotional, cognitive, and physical functioning. Developmental changes associated with puberty may put some early maturing girls at risk of shorter sleep duration in adolescence and exacerbate racial/ethnic disparities in health and well-being.

Neighborhood Factors and Urinary Metabolites of Nicotine, Phthalates, and Dichlorobenzene.

BACKGROUND AND OBJECTIVES: Exposures to environmental chemicals are ubiquitous in the US. Little is known about how neighborhood factors contribute to exposures. METHODS: Growing Up Healthy is a prospective cohort study of environmental exposures and growth and development among Hispanic and African American children (n = 506) in New York City. We sought to determine associations between neighborhood-level factors (eg, housing type, school, time spent indoors versus outdoors) and urinary biomarkers of chemical exposures suspected to be associated with these characteristics (cotinine, 2,5-dichlorophenol, and phthalate metabolites) adjusted by age, sex, race, and caregiver education and language. RESULTS: Urinary cotinine concentrations revealed a prevalent exposure to secondhand smoke; children living in public housing had higher concentrations than those in private housing. In homes with 1 smoker versus none, we found significant differences in urinary cotinine concentrations by housing, although not in homes with 2 or more smokers. Children in charter or public schools had higher urinary cotinine concentrations than those in private schools. School type was associated with exposures to both low- and high-molecular-weight phthalates, and concentrations of both exposure biomarkers were higher for children attending public versus private school. 2,5-Dichlorophenol concentrations declined from 2004 to 2007 (P = .038) and were higher among charter school children. CONCLUSIONS: Housing and school type are associated with chemical exposures in this minority, inner city population. Understanding the role of neighborhood on environmental exposures can lead to targeted community-level interventions, with the goal of reducing environmental chemical exposures disproportionately seen in urban minority communities.

Assessment of cumulative health risk in the World Trade Center general responder cohort.

BACKGROUND: Multiple comorbidities have been reported among rescue/recovery workers responding to the 9/11/2001 WTC disaster. In this study, we developed an index that quantifies the cumulative physiological burden of comorbidities and predicts life expectancy in this cohort. METHODS: A machine learning approach (gradient boosting) was used to model the relationship between mortality and several clinical parameters (laboratory test results, blood pressure, pulmonary function measures). This model was used to construct a risk index, which was validated by assessing its association with a number of health outcomes within the WTC general responder cohort. RESULTS: The risk index showed significant associations with mortality, self-assessed physical health, and onset of multiple chronic conditions, particularly COPD, hypertension, asthma, and sleep apnea. CONCLUSION: As an aggregate of several clinical parameters, this index serves as a cumulative measure of physiological dysregulation and could be utilized as a prognostic indicator of life expectancy and morbidity risk.

Childhood Socioeconomic Position and Pubertal Onset in a Cohort of Multiethnic Girls: Implications for Breast Cancer.

Background: Higher socioeconomic position (SEP) has been associated with increased risk of breast cancer. Its relationship with earlier age of pubertal onset, a risk factor for breast cancer, is less clear.Methods: We studied the relationship of SEP to pubertal onset in a multiethnic cohort of 1,237 girls ages 6 to 8 years at baseline. Girls in three U.S. cities were followed for 5 to 8 years with annual clinical examinations from 2004 to 2012. SEP measures were examined for associations with pubertal onset, assessed by breast budding (thelarche) and pubic hair development (adrenarche). Analyses were conducted with accelerated failure time models using a Weibull distribution, with left, right, and interval censoring.Results: Higher body mass index percentage at entry to the study and black or Hispanic race/ethnicity were the strongest predictors of age at pubertal onset. An SEP index comprising household family income, mother's education, and home ownership was an independent predictor of thelarche in adjusted models for all girls together and for white and Latina, separately, but not black girls, and the relationship varied by study site. The SEP index was not related to adrenarche in adjusted models. Overall, girls from the lowest quintile of SEP entered puberty on average 6% earlier than girls from the highest quintile (time ratio = 0.94; 95% confidence interval 0.91-0.97) in adjusted models.Conclusions: Our results suggest that early-life SEP may influence the timing of pubertal development.Impact: Factors related to lower SEP in childhood can adversely affect early development in ways that may increase the risk of breast cancer. Cancer Epidemiol Biomarkers Prev; 26(12); 1714-21. ©2017 AACR.

Opportunities and Challenges for Environmental Exposure Assessment in Population-Based Studies.

A growing number and increasing diversity of factors are available for epidemiological studies. These measures provide new avenues for discovery and prevention, yet they also raise many challenges for adoption in epidemiological investigations. Here, we evaluate 1) designs to investigate diseases that consider heterogeneous and multidimensional indicators of exposure and behavior, 2) the implementation of numerous methods to capture indicators of exposure, and 3) the analytical methods required for discovery and validation. We find that case-control studies have provided insights into genetic susceptibility but are insufficient for characterizing complex effects of environmental factors on disease development. Prospective and two-phase designs are required but must balance extended data collection with follow-up of study participants. We discuss innovations in assessments including the microbiome; mass spectrometry and metabolomics; behavioral assessment; dietary, physical activity, and occupational exposure assessment; air pollution monitoring; and global positioning and individual sensors. We claim the the availability of extensive correlated data raises new challenges in disentangling specific exposures that influence cancer risk from among extensive and often correlated exposures. In conclusion, new high-dimensional exposure assessments offer many new opportunities for environmental assessment in cancer development. Cancer Epidemiol Biomarkers Prev; 26(9); 1370-80. ©2017 AACR.

Breastfeeding versus formula-feeding and girls' pubertal development.

To examine the association of breastfeeding or its duration with timing of girls' pubertal onset, and the role of BMI as a mediator in these associations. A population of 1,237 socio-economically and ethnically diverse girls, ages 6-8 years, was recruited across three geographic locations (New York City, Cincinnati, and the San Francisco Bay Area) in a prospective study of predictors of pubertal maturation. Breastfeeding practices were assessed using self-administered questionnaire/interview with the primary caregiver. Girls were seen on at least annual basis to assess breast and pubic hair development. The association of breastfeeding with pubertal timing was estimated using parametric survival analysis while adjusting for body mass index, ethnicity, birth-weight, mother's education, mother's menarcheal age, and family income. Compared to formula fed girls, those who were mixed-fed or predominantly breastfed showed later onset of breast development [hazard ratios 0.90 (95 % CI 0.75, 1.09) and 0.74 (95 % CI 0.59, 0.94), respectively]. Duration of breastfeeding was also directly associated with age at onset of breast development (p trend = 0.008). Associations between breastfeeding and pubic hair onset were not significant. In stratified analysis, the association of breastfeeding and later breast onset was seen in Cincinnati girls only. The association between breast feeding and pubertal onset varied by study site. More research is needed about the environments within which breastfeeding takes place in order to better understand whether infant feeding practices are a potentially modifiable risk factor that may influence age at onset of breast development and subsequent risk for disease in adulthood.

Local food environments are associated with girls' energy, sugar-sweetened beverage and snack-food intakes.

OBJECTIVE: To describe availability and frequency of use of local snack-food outlets and determine whether reported use of these outlets was associated with dietary intakes. DESIGN: Data were cross-sectional. Availability and frequency of use of three types of local snack-food outlets were reported. Daily dietary intakes were based on the average of up to four 24 h dietary recalls. Multivariable linear regression models estimated average daily intakes of energy, sugar-sweetened beverages (SSB) and snack foods/sweets associated with use of outlets. SETTING: Multi-site, observational cohort study in the USA, 2004-2006. SUBJECTS: Girls aged 6-8 years (n 1010). RESULTS: Weekly frequency of use of local snack-food outlets increased with number of available types of outlets. Girls with access to only one type of outlet reported consuming food/beverage items less frequently than girls with access to two or three types of outlets (P <0·001). Girls' daily energy, SSB and snack foods/sweets intakes increased with greater use of outlets. Girls who reported using outlets>1 to 3 times/week consumed 0·27 (95 % CI 0·13, 0·40) servings of SSB more daily than girls who reported no use. Girls who reported using outlets>3 times/week consumed 449·61 (95 % CI 134·93, 764·29) kJ, 0·43 (95 % CI 0·29, 0·58) servings of SSB and 0·38 (95 % CI 0·12, 0·65) servings of snack foods/sweets more daily than those who reported no use. CONCLUSIONS: Girls' frequency of use of local snack-food outlets increases with the number of available types of outlets and is associated with greater daily intakes of energy and servings of SSB and snack foods/sweets.

Imputation method for lifetime exposure assessment in air pollution epidemiologic studies.

BACKGROUND: Environmental epidemiology, when focused on the life course of exposure to a specific pollutant, requires historical exposure estimates that are difficult to obtain for the full time period due to gaps in the historical record, especially in earlier years. We show that these gaps can be filled by applying multiple imputation methods to a formal risk equation that incorporates lifetime exposure. We also address challenges that arise, including choice of imputation method, potential bias in regression coefficients, and uncertainty in age-at-exposure sensitivities. METHODS: During time periods when parameters needed in the risk equation are missing for an individual, the parameters are filled by an imputation model using group level information or interpolation. A random component is added to match the variance found in the estimates for study subjects not needing imputation. The process is repeated to obtain multiple data sets, whose regressions against health data can be combined statistically to develop confidence limits using Rubin's rules to account for the uncertainty introduced by the imputations. To test for possible recall bias between cases and controls, which can occur when historical residence location is obtained by interview, and which can lead to misclassification of imputed exposure by disease status, we introduce an "incompleteness index," equal to the percentage of dose imputed (PDI) for a subject. "Effective doses" can be computed using different functional dependencies of relative risk on age of exposure, allowing intercomparison of different risk models. To illustrate our approach, we quantify lifetime exposure (dose) from traffic air pollution in an established case-control study on Long Island, New York, where considerable in-migration occurred over a period of many decades. RESULTS: The major result is the described approach to imputation. The illustrative example revealed potential recall bias, suggesting that regressions against health data should be done as a function of PDI to check for consistency of results. The 1% of study subjects who lived for long durations near heavily trafficked intersections, had very high cumulative exposures. Thus, imputation methods must be designed to reproduce non-standard distributions. CONCLUSIONS: Our approach meets a number of methodological challenges to extending historical exposure reconstruction over a lifetime and shows promise for environmental epidemiology. Application to assessment of breast cancer risks will be reported in a subsequent manuscript.

Associations between neighborhood resources and physical activity in inner-city minority children.

OBJECTIVE: The role of neighborhood physical activity resources on childhood physical activity level is increasingly examined in pediatric obesity research. We describe how availability of physical activity resources varies by individual and block characteristics and then examine its associations with physical activity levels of Latino and black children in East Harlem, New York City. METHODS: Physical activity resource availability by individual and block characteristics were assessed in 324 children. Availability was measured against 4 physical activity measures: average weekly hours of outdoor unscheduled physical activity, average weekly metabolic hours of scheduled physical activity, daily hours of sedentary behavior, and daily steps. RESULTS: Physical activity resource availability differed by race/ethnicity, caregiver education, and income. Presence of one or more playgrounds on a child's block was positively associated with outdoor unscheduled physical activity (odds ratio [OR] = 1.95, 95% confidence interval [CI] 1.11-3.43). Presence of an after-school program on a child's block was associated with increased hours of scheduled physical activity (OR = 3.25, 95% CI 1.41-7.50) and decreased sedentary behavior (OR = 3.24, 95% CI 1.30-8.07). The more resources a child had available, the greater the level of outdoor unscheduled physical activity (P for linear trend = .026). CONCLUSIONS: Neighborhood physical activity resource availability differs by demographic factors, potentially placing certain groups at risk for low physical activity level. Availability of select physical activity resources was associated with reported physical activity levels of East Harlem children but not with objective measures of physical activity.

World Trade Center disaster: assessment of responder occupations, work locations, and job tasks.

BACKGROUND: To date there have been no comprehensive reports of the work performedby 9/11 World Trade Center responders. METHODS: 18,969 responders enrolled in the WTC Medical Monitoring and Treatment Program were used to describe workers' pre-9/11 occupations, WTC work activities and locations from September 11, 2001 to June 2002. RESULTS: The most common pre-9/11 occupation was protective services (47%); other common occupations included construction, telecommunications, transportation, and support services workers. 14% served as volunteers. Almost one-half began work on 9/11 and >80% reported working on or adjacent to the ''pile'' at Ground Zero. Initially,the most common activity was search and rescue but subsequently, the activities of most responders related to their pre-9/11 occupations. Other major activities included security; personnel support; buildings and grounds cleaning; and telecommunications repair. CONCLUSIONS: The spatial, temporal, occupational, and task-related taxonomy reported here will aid the development of a job-exposure matrix, assist in assessment of disease risk, and improve planning and training for responders in future urban disasters.

Pubertal assessment method and baseline characteristics in a mixed longitudinal study of girls.

OBJECTIVES: The objective of this study was to describe the assessment methods and maturation status for a multisite cohort of girls at baseline recruitment and at ages 7 and 8 years. METHODS: The method for pubertal maturation staging was developed collaboratively across 3 sites. Girls at ages 6 to 8 years were recruited at 3 sites: East Harlem, New York; greater Cincinnati metropolitan area; and San Francisco Bay area, California. Baseline characteristics were obtained through interviews with caregivers and anthropometric measurements by trained examiners; breast stage 2 was defined as onset of pubertal maturation. The kappa statistic was used to evaluate agreement between master trainers and examiners. Logistic regression models were used to identify factors that are associated with pubertal maturation and linear regression models to examine factors that are associated with height velocity. RESULTS: The baseline cohort included 1239 girls. The proportion of girls who had attained breast stage 2 varied by age, race/ethnicity, BMI percentile, and site. At 7 years, 10.4% of white, 23.4% of black non-Hispanic, and 14.9% of Hispanic girls had attained breast stage>or=2; at 8 years, 18.3%, 42.9%, and 30.9%, respectively, had attained breast stage>or=2. The prime determinant of height velocity was pubertal status. CONCLUSIONS: In this multisite study, there was substantial agreement regarding pubertal staging between examiners across sites. The proportion of girls who had breast development at ages 7 and 8 years, particularly among white girls, is greater than that reported from studies of girls who were born 10 to 30 years earlier.

Prenatal organophosphate metabolite and organochlorine levels and performance on the Brazelton Neonatal Behavioral Assessment Scale in a multiethnic pregnancy cohort.

Prenatal exposures to organophosphate pesticides and polychlorinated biphenyls have been associated with abnormal neonatal behavior and/or primitive reflexes. In 1998-2002, the Mount Sinai Children's Environmental Health Center (New York City) investigated the effects of indoor pesticide use and exposure to polychlorinated biphenyls on pregnancy outcome and child neurodevelopment in an inner-city multiethnic cohort. The Brazelton Neonatal Behavioral Assessment Scale was administered before hospital discharge (n = 311). Maternal urine samples were analyzed for six dialkylphosphate metabolites and malathion dicarboxylic acid. A random subset of maternal peripheral blood samples from the entire cohort (n = 194) was analyzed for polychlorinated biphenyls and 1,1'-dichloro-2,2'-bis(4-chlorophenyl)ethylene. Malathion dicarboxylic acid levels above the limit of detection were associated with a 2.24-fold increase in the number of abnormal reflexes (95% confidence interval: 1.55, 3.24). Likewise, higher levels of total diethylphosphates and total dialkylphosphates were associated with an increase in abnormal reflexes, as was total dimethylphosphates after paraoxonase expression was considered. No adverse associations were found with polychlorinated biphenyl or 1,1'-dichloro-2,2'-bis(4-chlorophenyl)ethylene levels and any behavior. The authors uncovered additional evidence that prenatal levels of organophosphate pesticide metabolites are associated with anomalies in primitive reflexes, which are a critical marker of neurologic integrity.

Questionnaire assessment of nonoccupational pesticide exposure in epidemiologic studies of cancer.

Pesticides have been examined in epidemiologic studies as environmental risk factors for cancer, in part, due to the identification of carcinogenic properties of some of these chemicals using animal models. Although the majority of these epidemiologic studies have focused on occupational pesticide exposure, nonoccupational pesticide exposure has also been investigated. The objective of this paper is to review the methodological issues of nonoccupational pesticide exposure assessment, including identifying the methods that have been used to assess self-reported nonoccupational pesticide exposure in epidemiologic studies of cancer, and discussing the strengths and limitations of the current methodology as well as possible enhancements that could be incorporated into future investigations. Issues of exposure assessment that will be reviewed include specificity, recall, and characteristics of pesticide exposure. Additionally, sources of nonoccupational pesticide exposure other than residential will be briefly reviewed.