In utero and peripubertal metals exposure in relation to reproductive hormones and sexual maturation and progression among boys in Mexico City.

BACKGROUND: Endocrine disrupting chemicals (EDCs) such as metals have been reported to alter circulating reproductive hormone concentrations and pubertal development in animals. However, the relationship has rarely been investigated among humans, with the exception of heavy metals, such as Pb and Cd. Our aim was to investigate measures of in utero and peripubertal metal exposure in relation to reproductive hormone concentrations and sexual maturation and progression among boys from the Early Life Exposure in Mexico to Environmental Toxicants (ELEMENT) cohorts. METHODS: Our analysis included 118 pregnant women and their male children from the ELEMENT study. Essential and non-essential metals were measured in urine collected from the mothers during the third trimester of pregnancy and their male children at 8-14 years. Reproductive hormone concentrations [serum testosterone, estradiol, dehydroepiandrosterone sulfate (DHEA-S), inhibin B, and sex hormone-binding globulin (SHBG)] were measured in blood samples from the children at 8-14 years. We also assessed Tanner stages for sexual maturation (genital, pubic hair development, and testicular volume), at two time points (8-14, 10-18 years). We used linear regression to independently examine urinary metal concentrations in relation to each peripubertal reproductive hormones adjusting for child age and BMI. Generalized estimation equations (GEEs) were used to evaluate the association of in utero and peripubertal metal exposures with sexual maturation and progression during follow-up based on Tanner staging and testicular volume. RESULTS: In utero and prepubertal concentrations of some urinary metals were associated with increased concentrations of peripubertal reproductive hormones, especially non-essential metal(loid)s As and Cd (in utero), and Ba (peripubertal) as well as essential metal Mo (in utero) in association with testosterone. More advanced pubic hair developmental stage and higher testicular volume at the early teen visit was observed for boys with higher non-essential metal concentrations, including in utero Al and peripubertal Ba, and essential metal Zn concentration (peripubertal). These metals were also associated with slower pubertal progression between the two visits. CONCLUSION: These findings suggest that male reproductive development may be associated with both essential and non-essential metal exposure during in utero and peripubertal windows.

Accelerometer-measured Physical Activity, Reproductive Hormones, and DNA Methylation.

INTRODUCTION/PURPOSE: Limited studies have examined the association of physical activity with reproductive hormones, DNA methylation, and pubertal status among adolescents. METHODS: Among 248 boys and 271 girls, we estimated daily physical activity levels based on 7 d of wrist-worn accelerometer data. We used an isotemporal substitution paradigm and sex-stratified regression models to examine the association of physical activity levels with 1) testosterone, cortisol, progesterone, and androstenedione concentrations; 2) DNA methylation of long interspersed nucleotide (LINE-1) repeats and the genes H19, hydroxysteroid (11-Beta) dehydrogenase 2 (HSD11B2), and peroxisome proliferator-activated receptor alpha (PPARA) from blood leukocytes; and 3) Tanner stages, adjusted for age, BMI, and socioeconomic status. RESULTS: In boys, substituting 30 min of moderate physical activity for 30 min of sedentary behavior per day was associated with 29% (-49%, 0%) of lower testosterone and 29% (4%, 61%) of higher progesterone. Substituting 30 min of light physical activity for sedentary behavior was associated with 13% (-22%, -2%) of lower progesterone. Among girls, 30 min of additional sedentary behavior was associated with 8% (-15%, 0%) of lower testosterone and 24% (8%, 42%) of higher progesterone concentrations. Substituting 30 min of moderate physical activity for sedentary behavior was associated with 15% (0%, 31%) of higher cortisol, whereas substituting the same amount of light physical activity for sedentary behavior was associated with 22% (-39%, 0%) of lower progesterone. Substituting 30 min of vigorous physical activity for sedentary behavior per day was associated with almost six times higher levels (5.83, 95% confidence interval = 1.79-9.86) of HSD11B2 methylation in boys. CONCLUSIONS: Accelerometer-measured daily physical activity was associated with reproductive hormones and HSD11B2 DNA methylation, differed by sex and activity intensity levels.

In utero and peripubertal metals exposure in relation to reproductive hormones and sexual maturation and progression among girls in Mexico City.

There is increasing evidence that several metals are endocrine disrupting chemicals (EDCs). In utero development and adolescence are critical windows of susceptibility to EDC exposure. With the exception of a few heavy metals, few human studies have evaluated the impact of metal exposure on pubertal development. Our aim was to investigate measures of in utero and peripubertal metal exposure in relation to reproductive hormone levels and sexual maturation and progression among girls from the Early Life Exposure in Mexico to Environmental Toxicants (ELEMENT) cohorts. We measured urinary concentrations of aluminum (Al), arsenic (As), barium (Ba), cadmium (Cd), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), antimony (Sb), selenium (Se), and zinc (Zn) in samples collected from women during their third trimester of pregnancy and from their female children at 8-13 years (n = 132). We measured serum testosterone, estradiol, dehydroepiandrosterone sulfate (DHEA-S), inhibin B, and sex hormone-binding globulin (SHBG) at age 8-13, and assessed Tanner stages for sexual maturation (breast, pubic hair development, and menarche status), at two time points (8-13, 14-18 years). We used linear regression to independently examine in utero and peripubertal metal concentrations as predictors of peripubertal hormones. In a longitudinal analysis using generalized estimation equations, we evaluated Tanner stage and menarche progression in relation to individual in utero and peripubertal metal concentrations. We found that higher in utero Zn was associated with increased inhibin B. Several metals at 8-13 years were associated with higher DHEA-S and estradiol, while Ni was positively but Cu was negatively associated with testosterone. In utero Ni, Al, and Cd were associated with slower progression of breast development after adjustment for child age and BMI z-score. For example, an IQR increase in in utero Al exposure was associated with 0.82 times lower odds of progressing to a higher Tanner stage for breast development per year (95% CI: 0.68, 0.99). Peripubertal concentrations of Ba and Al were also associated with being at a higher pubic hair Tanner stage and menarche at 8-13, but lower odds of progressing to the next stage at 14-18 years. We used Bayesian kernel machine regression (BKMR) to model the joint effect of multiple metals while accounting for correlated exposures, as well as potential non-linear relationships between metals and outcomes of interest, which yielded results similar to individual analyses. These findings suggest that female reproductive development may be vulnerable to the effects of metal exposure, and using both Tanner stages and hormone levels may provide clues about underlying mechanisms in two sensitive periods of development.

An assessment of drinking water contamination with Helicobacter pylori in Lima, Peru.

BACKGROUND: Helicobacter pylori is a gut bacterium that is the primary cause of gastric cancer. H. pylori infection has been consistently associated with lack of access to sanitation and clean drinking water. In this study, we conducted time-series sampling of drinking water in Lima, Peru, to examine trends of H. pylori contamination and other water characteristics. MATERIALS AND METHODS: Drinking water samples were collected from a single faucet in Lima's Lince district 5 days per week from June 2015 to May 2016, and pH, temperature, free available chlorine, and conductivity were measured. Quantities of H. pylori in all water samples were measured using quantitative polymerase chain reaction. Relationships between the presence/absence and quantity of H. pylori and water characteristics in the 2015-2016 period were examined using regression methods accounting for the time-series design. RESULTS: Forty-nine of 241 (20.3%) of drinking water samples were contaminated with H. pylori. Statistical analyses identified no associations between sampling date and the likelihood of contamination with H. pylori. Statistically significant relationships were found between lower temperatures and a lower likelihood of the presence of H. pylori (P < .05), as well as between higher pH and higher quantities of H. pylori (P < .05). CONCLUSIONS: This study has provided evidence of the presence of H. pylori DNA in the drinking water of a single drinking water faucet in the Lince district of Lima. However, no seasonal trends were observed. Further studies are needed to determine the presence of H. pylori in other drinking water sources in other districts in Lima, as well as to determine the viability of H. pylori in these water sources. Such studies would potentially allow for better understanding and estimates of the risk of infection due to exposure to H. pylori in drinking water.

FPCA-based method to select optimal sampling schedules that capture between-subject variability in longitudinal studies.

A critical component of longitudinal study design involves determining the sampling schedule. Criteria for optimal design often focus on accurate estimation of the mean profile, although capturing the between-subject variance of the longitudinal process is also important since variance patterns may be associated with covariates of interest or predict future outcomes. Existing design approaches have limited applicability when one wishes to optimize sampling schedules to capture between-individual variability. We propose an approach to derive optimal sampling schedules based on functional principal component analysis (FPCA), which separately characterizes the mean and the variability of longitudinal profiles and leads to a parsimonious representation of the temporal pattern of the variability. Simulation studies show that the new design approach performs equally well compared to an existing approach based on parametric mixed model (PMM) when a PMM is adequate for the data, and outperforms the PMM-based approach otherwise. We use the methods to design studies aiming to characterize daily salivary cortisol profiles and identify the optimal days within the menstrual cycle when urinary progesterone should be measured.

Dietary Patterns Exhibit Sex-Specific Associations with Adiposity and Metabolic Risk in a Cross-Sectional Study in Urban Mexican Adolescents.

Background: Studies in Western nations have shown associations of certain dietary patterns with obesity and metabolic risk in youth. Little is known about these relations in newly industrialized countries where obesity prevalence is surpassing those of developed countries.Objective: We sought to characterize dietary patterns in a cross-sectional study in 224 adolescents aged 8-14 y in Mexico and to investigate associations of the dietary patterns with adiposity and metabolic risk.Methods: We used principal components analysis to derive dietary patterns from food-frequency questionnaire data. By using linear regression models that accounted for mother's marital status, education, and smoking habits and child's age and physical activity, we examined associations of the dietary patterns with adiposity [body mass index z score, waist circumference, the sum and ratio of the subscapular and triceps skinfold thicknesses, blood pressure, serum fasting glucose and a C-peptide-based measure of insulin resistance (CP-IR), lipid profile, and a metabolic syndrome risk z score (MetS z score)].Results: We identified a "prudent" dietary pattern characterized by high intakes of vegetables, fruit, fish, chicken, and legumes and a "transitioning" dietary pattern, which comprises processed meats, Mexican foods, and sweetened beverages. Each unit increase in the prudent pattern factor score corresponded with 0.33 ng/mL (95% CI: 0.09, 0.57 ng/mL) lower C-peptide, 0.08 units (95% CI: 0.02, 0.13 units) lower CP-IR, and a 0.14 unit (0.00, 0.27 unit) lower MetS z score in boys. In girls, the transitioning pattern corresponded with higher subscapular + triceps skinfold thickness (per 1-unit increase in the factor score: 2.46 mm; 95% CI: 0.10, 4.81 mm). These results did not change after accounting for pubertal status.Conclusions: A prudent dietary pattern was protective against metabolic risk in adolescent boys, whereas a transitioning dietary pattern corresponded with higher adiposity among adolescent girls. Given that adolescence is a key developmental period for long-term health, efforts to elucidate dietary determinants of metabolic risk during this life stage may have long-term benefits.

Phthalate and bisphenol A exposure during in utero windows of susceptibility in relation to reproductive hormones and pubertal development in girls.

BACKGROUND: Over the past several decades, the age of pubertal onset in girls has shifted downward worldwide. As early pubertal onset is associated with increased risky behavior and psychological issues during adolescence and cardiometabolic disease and cancer in adulthood, this is an important public health concern. Exposure to endocrine disrupting chemicals during critical windows of in utero development may play a role in this trend. Our objective was to investigate trimester-specific phthalate and BPA exposure in relation to pubertal development among girls in the Early Life Exposure in Mexico to Environmental Toxicants (ELEMENT) birth cohort. METHODS: We measured maternal urinary phthalate metabolites and BPA in samples collected during the first, second, and third trimesters of pregnancy. To assess reproductive development among their female children, we measured serum testosterone, estradiol, dehydroepiandrosterone sulfate (DHEA-S), inhibin B, and sex hormone-binding globulin (SHBG), and assessed sexual maturation, including Tanner staging for breast and pubic hair development and menarche status, at age 8-13 years (n = 120). We used linear and logistic regression to examine measures of trimester-specific in utero exposure as predictors of peripubertal hormone levels and pubertal onset, respectively. In secondary analyses, we evaluated estimated exposure at the midpoint of the first trimester and rates of change in exposure across pregnancy in relation to outcomes. RESULTS: Several phthalate metabolites measured throughout in utero development were associated with higher serum testosterone concentrations, while a number of metabolites measured in the third trimester were associated with higher DHEA-S. For example, an interquartile range (IQR) increase in mean monoethyl phthalate (MEP) levels across pregnancy was associated with 44% higher peripubertal testosterone (95% CI: 13-83%), while an IQR increase in di-2-ethylhexyl phthalate metabolites (ΣDEHP) specifically in the third trimester was associated with 25% higher DHEA-S (95%CI: 4.7-47%). In IQR increase in mean mono-2-ethylhexyl phthalate (MEHP) levels across pregnancy was associated with lower odds of having a Tanner Stage >1 for breast development (OR = 0.32, 95%CI: 0.11-0.95), while MEHP in the third trimester was associated with higher odds of having a Tanner Stage >1 for pubic hair development (OR = 3.76, 95%CI: 1.1-12.8). Results from secondary analyses were consistent with findings from our main analysis. CONCLUSION: These findings suggest that female reproductive development may be more vulnerable to the effects of phthalate or BPA exposure during specific critical periods of in utero development. This highlights the need for comprehensive characterizations of in utero exposure and consideration of windows of susceptibility in developmental epidemiological studies. Future research should consider repeated measures of in utero phthalate and BPA exposure within each trimester and across pregnancy.

Distributed Lag Models: Examining Associations Between the Built Environment and Health.

Built environment factors constrain individual level behaviors and choices, and thus are receiving increasing attention to assess their influence on health. Traditional regression methods have been widely used to examine associations between built environment measures and health outcomes, where a fixed, prespecified spatial scale (e.g., 1 mile buffer) is used to construct environment measures. However, the spatial scale for these associations remains largely unknown and misspecifying it introduces bias. We propose the use of distributed lag models (DLMs) to describe the association between built environment features and health as a function of distance from the locations of interest and circumvent a-priori selection of a spatial scale. Based on simulation studies, we demonstrate that traditional regression models produce associations biased away from the null when there is spatial correlation among the built environment features. Inference based on DLMs is robust under a range of scenarios of the built environment. We use this innovative application of DLMs to examine the association between the availability of convenience stores near California public schools, which may affect children's dietary choices both through direct access to junk food and exposure to advertisement, and children's body mass index z scores.

TNFα and IL-6 Responses to Particulate Matter in Vitro: Variation According to PM Size, Season, and Polycyclic Aromatic Hydrocarbon and Soil Content.

BACKGROUND: Observed seasonal differences in particulate matter (PM) associations with human health may be due to their composition and to toxicity-related seasonal interactions. OBJECTIVES: We assessed seasonality in PM composition and in vitro PM pro-inflammatory potential using multiple PM samples. METHODS: We collected 90 weekly PM10 and PM2.5 samples during the rainy-warm and dry-cold seasons in five urban areas with different pollution sources. The elements, polycyclic aromatic hydrocarbons (PAHs), and endotoxins identified in the samples were subjected to principal component analysis (PCA). We tested the potential of the PM to induce tumor necrosis factor alpha (TNFα) and interleukin 6 (IL-6) secretion in cultured human monocytes (THP-1), and we modeled pro-inflammatory responses using the component scores. RESULTS: PM composition varied by size and by season. PCA identified two main components that varied by season. Combustion-related constituents (e.g., vanadium, benzo[a]pyrene, benzo[a]anthracene) mainly comprised component 1 (C1). Soil-related constituents (e.g., endotoxins, silicon, aluminum) mainly comprised component 2 (C2). PM from the rainy-warm season was high in C2. PM (particularly PM2.5) from the dry-cold season was rich in C1. Elevated levels of cytokine production were associated with PM10 and C2 (rainy-warm season), whereas reduced levels of cytokine production were associated with PM2.5 and C1 (dry-cold season). TNFα secretion was increased following exposure to PM with high (vs. low) C2 content, but TNFα secretion in response to PM was decreased following exposure to samples containing ≥ 0.1% of C1-related PAHs, regardless of C2 content. The results of the IL-6 assays suggested more complex interactions between PM components and particle size. CONCLUSIONS: Variations in PM soil and PAH content underlie seasonal and PM size-related patterns in TNFα secretion. These results suggest that the mixture of components in PM explains some seasonal differences in associations between health outcomes and PM in epidemiologic studies. CITATION: Manzano-León N, Serrano-Lomelin J, Sánchez BN, Quintana-Belmares R, Vega E, Vázquez-López I, Rojas-Bracho L, López-Villegas MT, Vadillo-Ortega F, De Vizcaya-Ruiz A, Rosas Perez I, O'Neill MS, Osornio-Vargas AR. 2016. TNFα and IL-6 responses to particulate matter in vitro: variation according to PM size, season, and polycyclic aromatic hydrocarbon and soil content. Environ Health Perspect 124:406-412; http://dx.doi.org/10.1289/ehp.1409287.

A Multicomponent Behavioral Intervention to Reduce Stroke Risk Factor Behaviors: The Stroke Health and Risk Education Cluster-Randomized Controlled Trial.

BACKGROUND AND PURPOSE: The Stroke Health and Risk Education Project was a cluster-randomized, faith-based, culturally sensitive, theory-based multicomponent behavioral intervention trial to reduce key stroke risk factor behaviors in Hispanics/Latinos and European Americans. METHODS: Ten Catholic churches were randomized to intervention or control group. The intervention group received a 1-year multicomponent intervention (with poor adherence) that included self-help materials, tailored newsletters, and motivational interviewing counseling calls. Multilevel modeling, accounting for clustering within subject pairs and parishes, was used to test treatment differences in the average change since baseline (ascertained at 6 and 12 months) in dietary sodium, fruit and vegetable intake, and physical activity, measured using standardized questionnaires. A priori, the trial was considered successful if any one of the 3 outcomes was significant at the 0.05/3 level. RESULTS: Of 801 subjects who consented, 760 completed baseline data assessments, and of these, 86% completed at least one outcome assessment. The median age was 53 years; 84% subjects were Hispanic/Latino; and 64% subjects were women. The intervention group had a greater increase in fruit and vegetable intake than the control group (0.25 cups per day [95% confidence interval: 0.08, 0.42], P=0.002), a greater decrease in sodium intake (-123.17 mg/d [-194.76, -51.59], P=0.04), but no difference in change in moderate- or greater-intensity physical activity (-27 metabolic equivalent-minutes per week [-526, 471], P=0.56). CONCLUSIONS: This multicomponent behavioral intervention targeting stroke risk factors in predominantly Hispanics/Latinos was effective in increasing fruit and vegetable intake, reaching its primary end point. The intervention also seemed to lower sodium intake. Church-based health promotions can be successful in primary stroke prevention efforts. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01378780.

An Investigation of Organic and Inorganic Mercury Exposure and Blood Pressure in a Small-Scale Gold Mining Community in Ghana.

There is increasing concern about the cardiovascular effects of mercury (Hg) exposure, and that organic methylmercury and inorganic Hg(2+) may affect the cardiovascular system and blood pressure differentially. In small-scale gold mining communities where inorganic, elemental Hg exposures are high, little is known about the effects of Hg on blood pressure. In 2011, we assessed the relationship between Hg exposure and blood pressure (BP) in a cross-sectional study of adults from a small-scale gold mining community, Kejetia, and subsistence farming community, Gorogo, in Ghana's Upper East Region. Participants' resting heart rate and BP were measured, and hair and urine samples were provided to serve as biomarkers of organic and inorganic Hg exposure, respectively. Participants included 70 miners and 26 non-miners from Kejetia and 75 non-miners from Gorogo. Total specific gravity-adjusted urinary and hair Hg was higher among Kejetia miners than Kejetia non-miners and Gorogo participants (median urinary Hg: 5.17, 1.18, and 0.154 µg/L, respectively; hair Hg: 0.945, 0.419, and 0.181 µg/g, respectively). Hypertension was prevalent in 17.7% of Kejetia and 21.3% of Gorogo participants. Urinary and hair Hg were not significantly associated with systolic or diastolic BP for Kejetia or Gorogo participants while adjusting for sex, age, and smoking status. Although our results follow trends seen in other studies, the associations were not of statistical significance. Given the unique study population and high exposures to inorganic Hg, the work contained here will help increase our understanding of the cardiovascular effects of Hg.

Longitudinal Associations Between Neighborhood Physical and Social Environments and Incident Type 2 Diabetes Mellitus: The Multi-Ethnic Study of Atherosclerosis (MESA).

IMPORTANCE: Neighborhood environments may influence the risk for developing type 2 diabetes mellitus (T2DM), but, to our knowledge, no longitudinal study has evaluated specific neighborhood exposures. OBJECTIVE: To determine whether long-term exposures to neighborhood physical and social environments, including the availability of healthy food and physical activity resources and levels of social cohesion and safety, are associated with incident T2DM during a 10-year period. DESIGN, SETTING, AND PARTICIPANTS: We used data from the Multi-Ethnic Study of Atherosclerosis, a population-based cohort study of adults aged 45 to 84 years at baseline (July 17, 2000, through August 29, 2002). A total of 5124 participants free of T2DM at baseline underwent 5 clinical follow-up examinations from July 17, 2000, through February 4, 2012. Time-varying measurements of neighborhood healthy food and physical activity resources and social environments were linked to individual participant addresses. Neighborhood environments were measured using geographic information system (GIS)- and survey-based methods and combined into a summary score. We estimated hazard ratios (HRs) of incident T2DM associated with cumulative exposure to neighborhood resources using Cox proportional hazards regression models adjusted for age, sex, income, educational level, race/ethnicity, alcohol use, and cigarette smoking. Data were analyzed from December 15, 2013, through September 22, 2014. MAIN OUTCOMES AND MEASURES: Incident T2DM defined as a fasting glucose level of at least 126 mg/dL or use of insulin or oral antihyperglycemics. RESULTS: During a median follow-up of 8.9 years (37,394 person-years), 616 of 5124 participants (12.0%) developed T2DM (crude incidence rate, 16.47 [95% CI, 15.22-17.83] per 1000 person-years). In adjusted models, a lower risk for developing T2DM was associated with greater cumulative exposure to indicators of neighborhood healthy food (12%; HR per interquartile range [IQR] increase in summary score, 0.88 [95% CI, 0.79-0.98]) and physical activity resources (21%; HR per IQR increase in summary score, 0.79 [95% CI, 0.71-0.88]), with associations driven primarily by the survey exposure measures. Neighborhood social environment was not associated with incident T2DM (HR per IQR increase in summary score, 0.96 [95% CI, 0.88-1.07]). CONCLUSIONS AND RELEVANCE: Long-term exposure to residential environments with greater resources to support physical activity and, to a lesser extent, healthy diets was associated with a lower incidence of T2DM, although results varied by measurement method. Modifying neighborhood environments may represent a complementary, population-based approach to prevention of T2DM, although further intervention studies are needed.

Stroke Health and Risk Education (SHARE): design, methods, and theoretical basis.

BACKGROUND: Stroke is a disease with tremendous individual, family, and societal impact across all race/ethnic groups. Mexican Americans, the largest subgroup of Hispanic Americans, are at even higher risk of stroke than European Americans. AIM: To test the effectiveness of a culturally sensitive, church-based, multi-component, motivational enhancement intervention for Mexican Americans and European Americans in reducing stroke risk factors. METHODS: Participants enroll in family or friendship pairs, from the same Catholic church in the Corpus Christi Texas area, and are encouraged to change diet and physical activity behaviors and provide support for behavior change to their partners. Churches are randomized to either the intervention or control group. Goal enrollment for each of the 10 participating churches is 40 participant pairs. The intervention consists of self-help materials (including a motivational short film, cookbook/healthy eating guide, physical activity guide with pedometer, and photonovella), five motivational interviewing calls, two tailored newsletters, parish health promotion activities and environmental changes, and a peer support workshop where participants learn to provide autonomy supportive counseling to their partner. SHARE's three primary outcomes are self-reported sodium intake, fruit and vegetable intake, and level of physical activity. Participants complete questionnaires and have measurements at baseline, six months, and twelve months. Persistence testing is performed at 18 months in the intervention group. The trial is registered with clinicaltrials.gov (NCT01378780).

Bone lead and endogenous exposure in an environmentally exposed elderly population: the normative aging study.

OBJECTIVE: The objective of this study is to investigate the mobilization of lead from bone to blood (endogenous exposure) in a large epidemiologic population. METHODS: Study subjects were 776 participants in the Normative Aging Study. The subjects had their tibia lead, patella lead, blood lead, and urinary N-telopeptide (NTx) levels measured 1 to 4 times from 1991 to 2002. Regression models were estimated to quantify the association between tibia and patella lead and blood lead. We studied nonlinearity of the association, and explored possible factors that may modify it, including age and NTx levels. RESULTS AND CONCLUSIONS: There is significant association between bone lead and blood lead, and the association is nonlinear. The nonlinear associations between blood lead and bone lead are not significantly modified by age and NTx.

Differential effect of birthplace and length of residence on body mass index (BMI) by education, gender and race/ethnicity.

Although birthplace and length of residence have been found to be associated with Body Mass Index (BMI)/obesity in the USA, their effects may not be the same across groups defined by education, gender and race/ethnicity. Using cross-sectional population based data from the 2001 California Health Interview Survey, we investigated the associations of birthplace and US length of residence with BMI, and whether the influence of birthplace-US length of residence on BMI varied by education, gender and race/ethnicity. Our sample included 37,350 adults aged 25-64 years. Self-reported weight and height were used to calculate BMI. Birthplace and length of residence were combined into a single variable divided into five levels: US-born, foreign-born living in the United States for more than 15, 10-14, 5-9, and less than 5 years. Controlling for age, gender, marital status, race/ethnicity, education, income, fruit and vegetable consumption, current smoking and alcohol use, we found that: (1) foreign-born adults had lower BMI than US-born adults; (2) among foreign-born adults, longer residence in the United States was associated with higher BMI; and (3) the effect of birthplace-length of US residence on BMI differed by education level, gender and race/ethnicity. Specifically, longer residence in the United States was associated with the greatest percent increases in BMI among the lowest educated groups than higher educated groups, among women (vs. men) and among Hispanics (vs. other racial/ethnic groups). These findings suggest that a protective effect of foreign birthplace on BMI appears to attenuate with length of residence in the United States, and also reveal that BMI/obesity trajectories associated with length of US residence vary by education, gender and race/ethnicity. Immigrant status, independently and in combination with education, gender and race/ethnicity should be considered in future obesity prevention and reduction efforts.