Why religion and spirituality are important in human biological research.

The study of human biology includes exploration of all the genetic and environmental influences on human variation and life history, including impacts of sociocultural and physical environments. Religious practice and spirituality may be one of these influences. There are more than 5.8 billion religiously affiliated adults and children, accounting for 84% of the world's 6.9 billion people. Furthermore, 70% of Americans consider themselves spiritual in some way, including 22% who do not consider themselves religious, and the numbers for Europe are lower but proportionally similar. Such a high rate of religious affiliation and spiritual belief suggests that religion and spirituality could be sociocultural influences on human variation, but human biologists have scarcely attended to their impacts, as indicated by the limited numbers of relevant articles in the two flagship human biology journals. In this article, we discuss why human biologists may have overlooked this important force for human variability and highlight foundational work from human biology and other disciplines that can give our colleagues directions forward. We review the impacts of religion and spirituality at population and individual levels and call for human biologists to attend to the many aspects of religion and spirituality that can impact human biology and are much more than simply influences of denominational affiliation.

Maternal-infant interaction quality is associated with child NR3C1 CpG site methylation at 7 years of age.

OBJECTIVE: Infancy is both a critical window for hypothalamic-pituitary-adrenal (HPA) axis development, and a sensitive period for social-emotional influences. We hypothesized that the social-emotional quality of maternal-infant interactions are associated with methylation of HPA-axis gene NR3C1 later in childhood. METHODS: Using a subsample of 114 mother-infant pairs from the Avon Longitudinal Study of Parents and Children (ALSPAC), linear regression models were created to predict variance in methylation of seven selected CpG sites from NR3C1 in whole blood at age 7 years, including the main predictor variable of the first principal component score of observed maternal-infant interaction quality (derived from the Thorpe Interaction Measure at 12 months of age) and covariates of cell-type proportion, maternal financial difficulties and marital status at 8 months postnatal, child birthweight, and sex. RESULTS: CpG site cg27122725 methylation was negatively associated with warmer, more positive maternal interaction with her infant (ß = 0.19, p = .02, q = 0.13). In sensitivity analyses, the second highest quartile of maternal behavior (neutral, hesitant behavior) was positively associated with cg12466613 methylation. The other five CpG sites were not significantly associated with maternal-infant interaction quality. CONCLUSIONS: Narrow individual variation of maternal interaction with her infant is associated with childhood methylation of two CpG sites on NR3C1 that may be particularly sensitive to environmental influences. Infancy may be a sensitive period for even small influences from the social-emotional environment on the epigenetic determinants of HPA-axis function.

Factors associated with fruit and vegetable consumption among Burmese refugees.

OBJECTIVE: The Burmese population is one of the fast-growing refugee populations in the USA. This study investigated behavioural and environmental factors associated with fruit and vegetable (FV) consumption among Burmese refugees. DESIGN: We conducted a cross-sectional interview survey in 2018-2019. The 24-h recall was used to assess dietary behaviour. Multivariable logistic regression models were constructed with meeting the daily FV consumption recommendation (two or more servings of fruits and three or more servings of vegetables) as the outcome variable. We selected socio-economics, nutritional knowledge, food shopping frequency, ethnicity of preferred food store owners, perceived neighbourhood food environment and network distance to preferred food stores as potential explanatory variables. SETTING: Two Upstate New York counties. PARTICIPANTS: Burmese refugees (n 173) aged ≥18 years. RESULTS: Forty-five percentage of respondents met the daily FV consumption recommendation, and nearly all respondents identified ethnic (Burmese, Chinese/pan-Asian, or South Asian/halal) stores as their preferred stores to purchase FV. In the best-fit model, age (OR 1·08, 95 % CI (1·04, 1·12)) and shopping frequency (OR 1·51, 95 % CI (1·01, 2·26)) were positively associated, and network distance to preferred stores in kilometres (OR 0·81, 95 % CI (0·73, 0·90)) was negatively associated with meeting the daily FV consumption recommendation. No significant effect modifications by car ownership, poverty, length of stay in the USA and Supplemental Nutrition Assistance Program participation were detected. CONCLUSIONS: The findings suggested that having Asian ethnic food stores within a short, walkable distance from home and shopping at these stores often can promote healthy dietary behaviour among Burmese refugees.

Exposure of Akwesasne Mohawk women to polychlorinated biphenyls and hexachlorobenzene is associated with increased serum levels of thyroid peroxidase autoantibodies.

Persistent organic pollutants (POPs) including polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), and dichlorodiphenyltrichloroethane (p,p'-DDT) were reported to influence immunological activity. As endocrine-disrupting chemicals (EDC), these pollutants may disrupt normal thyroid function and act as catalysts for development of autoimmune thyroid disease by directly and indirectly affecting levels of thyroid peroxidase antibodies (TPOAbs). Native American communities are disproportionately exposed to harmful toxicants and are at an increased risk of developing an autoimmune disease. The aim of this study was to determine the association between POPs and TPOAbs in serum obtained from Native American women. This assessment was used to measure whether increased risk of autoimmune thyroid disease occurred as a result of exposure to POPs. Data were collected from 183 Akwesasne Mohawk women, 21-38 years of age, between 2009 and 2013. Multivariate analyses were conducted to determine the association between toxicant exposure and levels of TPOAbs. In multiple logistic regression analyses, exposure to PCB congener 33 was related to elevated risk of individuals possessing above normal levels of TPOAbs. Further, HCB was associated with more than 2-fold higher risk of possessing above normal levels of TPOAbs compared to women with normal levels of TPOAbs. p,p'-DDE was not associated with TPOAb levels within this study. Exposure to PCB congener 33 and HCB was correlated with above normal levels of TPOAbs, a marker of autoimmune thyroid disease. Additional investigations are needed to establish the causes and factors surrounding autoimmune thyroid disease which are multiple and complex.

Age at menarche and chemical exposure: per- and polyfluoroalkyl substances (PFAS), dichloro-diphenyl-trichloroethane (DDT), dichloro-diphenyl-dichloroethylene (DDE), and polychlorinated biphenyls (PCBs).

CONTEXT: Humans are now exposed to a multitude of chemicals throughout the life course, some of which may affect growth and development owing to their endocrine-like activity. OBJECTIVE: To assess the relationship of suspect toxicants to maturation, specifically to age at menarche. METHODS: We conducted two systematic reviews of age at menarche and PFOA, PFOS, PCBs and DDE/DDT based on publications indexed by pubmed. RESULTS: 16 unique reports were identified. Most studies of PFOA and PFOS reported either no association or delays in the age at menarche; only one reported an earlier age. Studies of DDT and DDE were more mixed. Reports on PCBs varied by PCB congener group with an equal number of them reporting delays and no association but one an acceleration. Sources of variation in results include the timing of exposure assessment (prenatal vs. postnatal), level of the toxicant, and sample size. No obvious pattern to the variation in results could be tied to those sources of variation. CONCLUSION: The absence of consistent evidence from multiple reports of earlier age at menarche suggests that these toxicants may not be responsible for accelerated sexual maturation in girls. However, human populations naturally vary in the variety and levels of exposure, making the comparison of studies difficult. Further, studies vary in methodology, complicating aggregation of results and generalisations.

Linking infant size and early growth with maternal lifestyle and breastfeeding - the first year of life in the CRIBS cohort.

BACKGROUND: Every third child in Croatia is classed as overweight or obese. Infant growth can represent early warning signs for obesity. AIM: To detect early risk factors for obesity by investigating infant size and early growth trajectories and their association with maternal lifestyle and breastfeeding. SUBJECTS AND METHODS: Ninety-eight mother-child pairs from the Croatian Islands' Birth Cohort Study (CRIBS) cohort were included in the study. Data were collected from questionnaires and medical records. Growth data were converted to Z-scores using World Health Organisation (WHO) standards and used as the primary outcome. RESULTS: Z-score trajectories in the first year of life were in line with WHO standards. A direct link between infant size and maternal socioeconomic status (SES) or breastfeeding was not detected. However, child weight gain in the first 6 months was associated with maternal body mass index (BMI) before pregnancy (p < 0.01). A positive association was also established between breastfeeding and maternal SES and mothers that report an unhealthy diet have heavier children (p < 0.05, respectively). CONCLUSION: Infant size and early growth in Croatia is in line with WHO standards and risk factors for obesity development were detectable in the first year of life, but not highly pronounced. However, more effective BMI monitoring and promotion of a healthy diet and lifestyle of women before and during pregnancy is needed.

Deep phenotyping of pubertal development in Norwegian children: the Bergen Growth Study 2.

BACKGROUND: The Bergen Growth Study 2 (BGS2) aims to characterise somatic and endocrine changes in healthy Norwegian children using a novel methodology. SUBJECTS AND METHODS: A cross-sectional sample of 1285 children aged 6-16 years was examined in 2016 using novel objective ultrasound assessments of breast developmental stages and testicular volume in addition to the traditional Tanner pubertal stages. Blood samples allowed for measurements of pubertal hormones, endocrine disruptive chemicals, and genetic analyses. RESULTS: Ultrasound staging of breast development in girls showed a high degree of agreement within and between observers, and ultrasound measurement of testicular volume in boys also showed small intra- and interobserver differences. The median age was 10.4 years for Tanner B2 (pubertal onset) and 12.7 years for menarche. Norwegian boys reached a pubertal testicular volume at a mean age of 11.7 years. Continuous reference curves for testicular volume and sex hormones were constructed using the LMS method. CONCLUSIONS: Ultrasound-based assessments of puberty provided novel references for breast developmental stages and enabled the measurement of testicular volume on a continuous scale. Endocrine z-scores allowed for an intuitive interpretation of changing hormonal levels during puberty on a quantitative scale, which, in turn, provides opportunities for further analysis of pubertal development using machine-learning approaches.

Associations between autoimmune dysfunction and pollutants in Akwesasne Mohawk women: Dichlorodiphenyltrichloroethane and polychlorinated biphenyl exposure.

BACKGROUND: Pollutant exposures, including polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT), have been found to disrupt normal immune function. Native American communities are disproportionately affected by autoimmune dysfunction and are more likely to be exposed to harmful pollutants than the general population. OBJECTIVE: To determine the association between autoimmune dysfunction and pollutant exposure levels, this study evaluates the statistical relationship between the presence of autoimmune dysfunction and pollutant exposure. METHODS: Information was collected from Akwesasne Mohawk women (n = 182), 21-39 years of age, between 2009 and 2013. Data collection included anthropometric measurements, medical diagnoses of autoimmune disease and symptoms of autoimmune dysfunction in the medical record, and blood draws for measurement of pollutants. Multivariate analyses determined the association between toxicant exposure and autoimmune dysfunction. RESULTS: Toxicant p,p'-DDE was positively associated with an almost two-fold risk of autoimmune dysfunction. p,p'-DDE and PCB congeners 32, 136, and 138 were positively associated in a multivariate analysis with an autoimmune diagnosis. CONCLUSIONS: Pollutant exposures, specifically to p,p'-DDE and some PCB congeners, are common exposures that are associated with autoimmune dysfunction and autoimmune disease, although there are other factors and causes related to autoimmune dysfunction incidence.

Testing the Institute of Medicine (IOM) recommendations on maternal reproductive health and associated neonatal characteristics in a transitional, Mediterranean population.

BACKGROUND: High pre-pregnancy body mass index (BMI) and excessive gestational weight gain (GWG) are significant risk factors for maternal and neonatal health. AIM: To assess pre-pregnancy BMI and GWG during pregnancy and their association with different maternal and neonatal characteristics in the transitional Mediterranean population from the Eastern Adriatic islands. SUBJECTS AND METHODS: Two hundred and sixty-two mother-child dyads from the CRoatian Islands' Birth Cohort Study (CRIBS) were included in the study. Chi-square test, ANOVA, and regression analysis were used to test the association between selected characteristics. RESULTS: In total, 22% of women entered pregnancy as overweight/obese and 46.6% had excessive GWG. Pre-pregnancy overweight and obesity were significantly associated with elevated triglycerides uric acid levels, and decreased HDL cholesterol in pregnancy. Excessive GWG was associated with elevated fibrinogen and lipoprotein A levels. Women with high pre-pregnancy BMI and GWG values were more likely to give birth to babies that were large for gestational age (LGA), additionally confirmed in the multiple logistic regression model. CONCLUSION: High maternal pre-pregnancy BMI and excessive GWG were both significantly associated with deviated biochemical parameters and neonatal size. More careful monitoring of maternal nutritional status can lead to better pre- and perinatal maternal healthcare.

Sex differences in the association of measures of sexual maturation to common toxicants: Lead, dichloro-diphenyl-trichloroethane (DDT), dichloro-diphenyl-dichloroethylene (DDE), and polychlorinated biphenyls (PCBs).

Many studies of human toxicant exposure examine the hypothesis that human sexual maturation can be affected through endocrine disruption. Within this body of literature there is significant variation in the findings. Variation may be related to the differential effects by toxicants between males and females as well as variation in sample size, toxicant levels, and the timing of exposure. We review sexual maturation outcomes between males and females when exposed to lead, dichlorodiphenyldichloroethylene (DDE), dichloro-diphenyl-trichloroethane (DDT), and polychlorinated biphenyls (PCBs) using a systematic process to gather peer-reviewed studies published from January 1994 through December 2019 on the NCBI website's PubMed search engine. The review includes 34 studies, some comprised of multiple analyses, to compare effects on sexual maturation by sex. The analysis shows that both boys and girls have delayed sexual maturation in relation to lead exposure. There are differences in the direction of effects associated with DDE/DDT and PCB exposure in boys and girls. PCBs exist as congeners of many structural forms, and that variation is considered in this review. Dioxin-like and non-dioxin-like PCBs exposure directionality differed between boys and girls as well. Future investigations into the basis of sex variation in DDE/DDT and PCB relationships to sexual maturation are warranted.

Trends in height, weight, BMI, skinfolds, and measures of overweight and obesity from 1979 through 1999 among American Indian Youth: The Akwesasne Mohawk.

BACKGROUND/OBJECTIVES: Information on recent changes in overweight, obesity, and adiposity among American Indians is scarce. To assess changes in size and adiposity among American Indian youth, data from two samples of Akwesasne Mohawk youth, were compared. SUBJECTS/METHODS: Both project 1, conducted in 1979 (n = 75) and Project 2, conducted between 1996 and 1999 (n = 206), sampled youth 10-14 years of age from the Akwesasne Mohawk Reservation (aka St. Regis) that borders New York state, and Ontario and Quebec provinces. Heights, weights, and skinfold thicknesses were converted to z-scores using CDC reference values. BMI status was calculated in terms of WHO age-specific cutoffs and CDC cutoffs. RESULTS: z-Scores for heights differed little between projects. The between-project difference in weight z-score is twice the between-project z-score difference for height. Differences among males are larger and more often significant. Triceps and subscapular skinfold thickness are significantly greater in Project 2. The rate of overweight and obesity combined, increased 3.3-fold. In multiple regression analyses with sex, height, and age in the model, project is a significant predictor of weight and skinfolds. CONCLUSIONS: Weight and adiposity have increased substantially from 1979 to 1996-99. Overweight and obesity became significantly more common. Given the increase in adiposity, these youth may be facing significant health risks as adults in terms of cardiovascular disease, cancer, and type II diabetes unless weight and adiposity is reduced.

Modern water: A biocultural approach to water pollution at the Akwesasne Mohawk Nation.

OBJECTIVES: The goal of this article is to review a body of research around water contamination conducted in the Akwesasne Mohawk Nation between 1995 and 2016, place these findings in a biocultural context, and consider implications for a human biology of water. METHODS: This review draws on research projects conducted in partnership with the Akwesasne Mohawk Nation living along the St. Lawrence River as well as published research by others on water contamination at Akwesasne. Quantitative and qualitative methods including toxicological and epidemiological methods, surveys, and ethnographic studies are included. RESULTS: Pollution of a river with polychlorinated biphenyls (PCBs) contaminated local fish, a major, traditional, food source. Following health advisories to avoid consuming local fish, consumption and PCB levels decreased. PCB levels were negatively associated with health outcomes. In adolescents, higher PCB levels were associated with advanced sexual maturation in females, reduced testosterone in males and reduced thyroxine levels in young adults. Avoiding fish consumption altered traditional dietary patterns and social interactions, generational transmission of knowledge, and relations between generations, all of which impacted cultural forms and may have added to the perceived injustices in this Native American community. Items substituted for fish may have contributed to increasing rates of obesity as well. CONCLUSIONS: Water pollution has immediate direct health consequences as well as cultural impacts related to changed food consumption and altered patterns of social interaction.

Doing biocultural anthropology: Continuity and change.

Biocultural anthropology has long represented an important approach in the study of human biology. However, despite demonstrated utility, its somewhat amorphous identity leaves some scholars questioning just what it means to be biocultural. In this article, rather than providing proscriptive doctrine, we contribute to these conversations about the nature of biocultural anthropology by considering what biocultural research does. We begin with a consideration of some of the foundational themes of biocultural work including recognition of the dialectical nature of sociocultural and biological forces, interest in inequality, and incorporation of both evolutionary and political economic perspectives. To emphasize the consistency of biocultural work over time, we also trace these themes from originating work to their appearance in current research. We then identify some of the key actions of the biocultural approach, noting that biocultural work can execute any number though rarely all of these actions simultaneously. We then offer brief introductions to the articles that make up this special issue, highlighting the ways in which each piece undertakes key biocultural actions. Following these introductions, we provide a discussion of some of the types of biocultural work that are not present in this special issue, recognizing the breadth of biocultural research across multiple subfields of anthropology. Finally, we point to some potentially fruitful directions for future biocultural research. In the end, we conclude that while biocultural anthropology may not have a cohesive or set agenda, it does have a clear and recognizable form of content and methodology illuminated by its actions.

Social Support During Pregnancy Modifies the Association Between Maternal Adverse Childhood Experiences and Infant Birth Size.

Introduction Adverse childhood experiences (ACEs) can deleteriously affect health, including pregnancy and birth outcomes occurring later in life. Identification of modifiable factors during pregnancy that buffer the ill effects of adversity is warranted. Social support during pregnancy can promote better birth outcomes, yet it is unknown whether it could also mitigate perinatal risks stemming from ACEs. Thus, this study considers multiple forms of social support in pregnancy as modifiers of an ACEs and fetal growth association. Methods Data were collected from mother and infant pairs from an ongoing prospective birth cohort. Women enrolled around 27 weeks gestation and completed gold-standard assessments of ACEs and social support. Infant cephalization index scores [(head circumference /birthweight) × 100; a marker of asymmetric fetal growth] were derived. Multivariable regression models tested main effects and interaction between ACEs and social support in relation to infant cephalization. Results Higher levels of ACEs were associated with higher cephalization scores (ß = 0.01, SE = 0.01, p < 0.05) whereas higher social support was associated with lower cephalization scores (ß = - 0.03, SE = 0.01, p < 0.05). A significant interaction was observed showing a protective effect of social support among those with low (0 events) and moderate (1-3 events) ACEs but not among those with high ACEs (4 + events; p < 0.05). Tangible and emotional support, but not information support, contributed to the associations. Discussion Maternal ACEs can deleteriously affect birth size, yet social support during pregnancy provides some buffer from its enduring effects. Interventions designed to enhance pregnancy social support may not only improve maternal wellbeing, but may also safeguard infant health.

Persistent organic pollutants as predictors of increased FSH:LH ratio in naturally cycling, reproductive age women.

Although several recent studies suggest endocrine disrupting compounds, such as polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (p,p', DDE), and hexachlorobenzene (HCB), target different organs and systems in the body, their impact on female reproductive function in humans is not well characterized. We seek to determine the relationship between several known endocrine disrupting compounds and a marker of ovarian responsivity, the FSH:LH ratio (higher ratio indicates less ovarian responsivity). For this analysis, 169 naturally cycling women between 21 and 38 years of age completed interviews and had their blood drawn on day 3 of their menstrual cycle for analyses of toxicants, gonadal sex hormones (E2 and P4), and gonadotropins (FSH and LH). PCB congeners were classified into five groups based on their environmental persistence, distribution in human tissue, and toxicological action, reflecting the structure, mechanism, and known biological activity of individual PCB congeners. For every unit (ppb) increase in the level of the estrogenic PCB group, there was a 5-fold greater risk of a FSH:LH ratio ≥ 2, controlling for individual differences in age, percent body fat, cycle day 3 estradiol levels, parity, alcohol use and cigarette smoking in the past year (exp[ß] = 5; p = ≤0.01). PCB congeners identified as estrogenic were analyzed individually, and, of the 19 potentially estrogenic congeners, five were significantly, and positively related to an increased FSH:LH ratio. Four of these congeners are non-persistent, easily volatilize in the environment, and are easily metabolized, and hence, are indicative of very recent or current exposure. p,p'-DDE and HCB were not associated with FSH:LH ratio. We find a clinical indicator of ovarian responsivity, FSH:LH ratio, is associated with a specific group of estrogenic PCBs. These congeners may become airborne when they volatilize from dredged PCB-contaminated soil or from indoor PCB-containing window caulk and sealants in older buildings leading to inhalation exposure. PCB exposure, particularly to non-persistent, estrogenic congeners, may pose an unrecognized threat to female fecundity within the general population.

Maternal-infant interaction as an influence on infant adiposity.

OBJECTIVES: The aim of this research is to identify whether specific aspects of the early life psychosocial environment such as quality of home and maternal-infant interaction are associated with increased infant adiposity, in a disadvantaged population in the United States. METHODS: Data on 121 mother-infant pairs from the Albany Pregnancy and Infancy Lead Study were analyzed using three multiple linear regression models with subscapular skinfold thickness (SST), triceps skinfold thickness (TST), and weight z-scores at 12 months of age as outcome variables. Maternal-infant interaction was indexed by the Nursing Child Assessment Teaching Scales (NCATS) and home environment quality was indexed by the Home Observation for Measurement of the Environment (HOME). RESULTS: In models including infant birth weight, cigarette use in second trimester, infant caloric intake at 9-12 months, size at birth for gestational age, infant sex, and mother's prepregnancy BMI, specific subscales of NCATs predicted infant adiposity z-scores. Poorer mother's response to infant distress was associated with greater SST ( ß = -0.20, P = .02), TST ( ß = -0.19, P = .04), and weight ( ß = -0.14, P = .05). Better maternal sensitivity to infant cues was associated with larger SST ( ß = 0.25, P < .01), while mother's poorer social-emotional growth fostering predicted greater SST ( ß = -0.23, P < .01) and weight ( ß = -0.16, P = .03). Better scores on HOME Organization of the Environment were associated with greater SST ( ß = 0.34, P = .02) and TST ( ß = 0.33, P = .04). CONCLUSIONS: Emotionally relevant aspects of the maternal-infant interaction predicted infant adiposity, though in different directions. This indicates that the psychosocial environment, through maternal behavior, may influence infant adiposity. However, the general home environment was not consistently related to infant adiposity.

Endocrine disrupting chemicals and ovulation: Is there a relationship?

Although the potential for endocrine disrupting chemicals (EDCs) to disrupt female fecundity is great, few studies have assessed the threat to human reproduction. This study investigates levels of organochlorines in relation to their impact on women's menstrual cycles and ovulatory status. To address concerns of the Akwesasne Mohawk community in upstate New York regarding well-established exposure to EDCs, women's fertility and reproductive health endpoints, we recruited 215 women between the ages of 21 and 38 years to measure menstrual cycle characteristics and levels of local pollutants. Of these, 155 women collected saliva over the course of their menstrual cycle allowing for analysis of estradiol and progesterone levels and the determination of ovulatory status in relationship to their serum pollutant levels. A subset of participants (15) who did not commence cycling within a month of their enrollment were not included in the analysis, hence reducing the sample size to 140 participants. Additionally, a lipid panel, estradiol and progesterone were assessed in serum on Day 3 of the menstrual cycle. Median cycle length for women in the sample was 29 days. After aligning the cycles, 110 women were considered ovulatory and 45 (29%) anovulatory. Concentrations of groups of more persistent PCBs congeners, HCB, and p,p'-DDE did not differ significantly with ovulatory status. However, a sub-group of low-chlorinated PCB congeners, considered to be estrogenic were significantly higher among anovulatory women. These findings suggest that certain EDC's, ubiquitous in our environment, may adversely affect menstrual cycles and thus have the capacity to impair reproductive function, including likelihood of conception.

Changes in persistent organic pollutant levels from adolescence to young adulthood.

Elimination rates and their corresponding half-lives are conceptually important and intuitively accessible pharmacokinetic measures of toxicant elimination, but regression-based estimates are biased proportional to the degree of continuing (background) exposure. We propose an alternative estimator, the censored normal regression model, which uses all observations, but treats individuals whose initial level failed to exceed their follow-up level as censored observations to weight the regression estimates from those that declined between blood draws. In this manner, we derive the intrinsic elimination rate, the elimination rate free from ongoing exposure, as a parameter in a regression with an unobserved, latent dependent variable. We utilize sequential measurements of persistent organic pollutants (POPs) levels from adolescence to adulthood, a period of intense change in size and body composition, to quantify individual-level change within a community exposed to significant quantities of contaminants over an extended period of time. Although much research has been conducted on effects of POPs, far less attention has been given to vectors of intake and changes in toxicant levels during the life course. We apply exploratory factor analysis (EFA) to types and timing of consumption, along with physical behavioral characteristics, to identify a structure of seven underlying factors. Although several variables show factorial complexity, the latent constructs included an age/maturation and period-related factor, a nutritional composite, consumption prior to pregnancy, fish and fowl consumed during pregnancy, factors distinguishing body mass and weight from height, and bottom-feeding fish consumption. Unadjusted and adjusted half-lives using the censored normal regression estimator, as well as estimated half-lives from conventional log concentration regressions, are reported for PCB groupings, specific congeners, p,p'-DDE, and HCB.