Growth as a mirror: is endocrine disruption challenging Tanner's concept?

Contaminant Exposure Profiles Demonstrate Similar Physiological Effects Across Environments Despite Unique Profile Composition in Formosa, Argentina, and Connecticut, USA

OBJECTIVE

Exposure to environmental contaminants is globally universal. However, communities vary in the specific combination of contaminants to which they are exposed, potentially contributing to variation in human health and creating "locally situated biologies." We investigated how environmental exposures differ across environments by comparing exposure profiles between two contexts that differ markedly across political, economic, and sociocultural factors-Namqom, Formosa, Argentina, and New Haven, Connecticut, United States.

METHODS

We collected infant urine, maternal urine, and human milk samples from mother-infant dyads in Formosa (n = 13) and New Haven (n = 21). We used untargeted liquid chromatography with high-resolution mass spectrometry (LC-HRMS) to annotate environmental contaminants and endogenous metabolites in these samples, and we analyzed the data using exposome-wide association studies (EWAS) followed by pathway enrichment.

RESULTS

We found statistically significant differences between the chemical exposure profiles of the Argentinian and US mothers, mostly involving pesticides; however, we observed similarities in the infant urine and human milk environmental contaminant profiles, suggesting that the maternal body may buffer infant exposure through human milk. We also found that infants and mothers were exposed to contaminants that were associated with alterations in amino acid and carbohydrate metabolism. Infants additionally showed alterations in vitamin metabolism, including vitamins B1, B3, and B6.

CONCLUSIONS

Differences in chemical exposure profiles may be related to structural factors. Despite variation in the composition of exposure profiles between the two study sites, environmental contaminant exposure was associated with similar patterns in human physiology when we considered contaminants comprehensively rather than individually, with implications for metabolic and cardiovascular disease risk as well as infant cognitive development.

Bergmann's rule is a "just-so" story of human body size

Carl Bergmann was an astute naturalist and physiologist. His ideas about animal size and shape were important advances in the pre-Darwinian nineteenth century. Bergmann's rule claims that that in cold climates, large body mass increases the ratio of volume-to-surface area and provides for maximum metabolic heat retention in mammals and birds. Conversely, in warmer temperatures, smaller body mass increases surface area relative to volume and allows for greater heat loss. For humans, we now know that body size and shape are regulated more by social-economic-political-emotional (SEPE) factors as well as nutrition-infection interactions. Temperature has virtually no effect. Bergmann's rule is a "just-so" story and should be relegated to teaching and scholarship about the history of science. That "rule" is no longer acceptable science and has nothing to tell us about physiological anthropology.

Blood lead level and nutritional status indicators in preadolescent Polish schoolchildren

BACKGROUND

Environmental pollutions with heavy metals may have toxic effects on human health and development. One of the most detrimental is lead exposure, which may disturb neurodevelopment and linear growth in children. However, data on the effect of lead exposure on nutritional and weight status in children are limited, thus this study aimed to assess the effect of blood lead (Pb) level on nutritional and weight status in preadolescent schoolchildren from the industrialized, mining region in southwestern Poland.

METHODS

Our study sample involved N = 709 schoolchildren (402 boys and 307 girls) in the preadolescent developmental period (7-11 years of age for boys and 7-10 years of age for girls). Anthropometric measurements were used to assess nutritional and weight status: body mass index (BMI), mid-upper arm circumference (MUAC) and skinfolds thicknesses (triceps, subscapular, abdominal and the sum of skinfolds). Blood Pb level was evaluated and divided into two groups: above (>3.7 μg/dL) and below median value (≤3.7 μg/dL).

RESULTS

Analysis of covariance (with children's age controlled as a covariate) revealed that children with blood Pb level above median value had significantly lower values of BMI, MUAC and all skinfolds (at least p < 0.01). However, this effect was significant only in boys, whereas in girls differences were non-significant (p > 0.05). The highest effect size of blood Pb level was noted for skinfolds thicknesses (partial η²: 0.015 for the sum of skinfolds).

CONCLUSIONS

Nutritional status in children with higher blood Pb level is significantly impaired in preadolescent boys, who appear to be more sensitive to this environmental factor. Our findings indicate a particular need for nutritional and environmental interventions among preadolescent children in regions with higher lead exposure.

Marginal Food Security Predicts Earlier Age at Menarche Among Girls From the 2009-2014 National Health and Nutrition Examination Surveys

STUDY OBJECTIVE

This study analyzed the relationship between household food security and variation in age at menarche, as well as the connections between food insecurity, nutritional status, and allostatic load, among girls aged 12-15 years from the 2009-2014 United States National Health and Nutrition Examination Survey (NHANES).

METHODS

Data analysis included mean comparisons of age at menarche among household food security groups (high, marginal, low, and very low) as well as categorical variables known to associate with age at menarche (ethnicity, poverty status, body mass index [BMI], allostatic load, and milk consumption). χ² Analyses were used to test the associations between household food security and additional categorical variables. Univariate and multivariate regression models were used to test the relationship between variation in age at menarche and household food security, ethnicity, BMI, and allostatic load categories while controlling for age.

RESULTS

Non-Hispanic Black and Hispanic/Mexican American girls had earlier mean ages at menarche, higher mean BMIs, and disproportionately experienced household food insecurity when compared to non-Hispanic White-identifying girls. In the univariate analyses, marginal household food security, Hispanic/Mexican American and Black ethnicities, overweight and obese BMI categories, and marginal-high allostatic load were each associated with lower age at menarche compared to reference categories. These associations were maintained in the multivariate analysis, although only Hispanic/Mexican American ethnicity predicted earlier menarche when compared to that of non-Hispanic White girls.

CONCLUSIONS

Marginal household food security, particularly for girls who identified as non-White, predicted earlier age at menarche independent of nutritional status and allostatic load. At the same time, having more energetic resources (ie, higher BMI) also significantly predicted earlier menarche.

Exposure to perfluoroalkyl substances (PFAS) and dyslipidemia, hypertension and obesity in adolescents. The Fit Futures study

BACKGROUND

Prevalence of obesity, hypertension and dyslipidemia has been increasing in children and adolescents worldwide. Exposure to environmental pollutants may contribute to this development. Our aim was to study associations between perfluoroalkyl substances (PFAS) and dyslipidemia, hypertension and obesity in a population-based sample of adolescents.

METHODS

Serum PFAS concentrations were measured in 940 adolescents, mean age 16.4 (SD 1.3) years, from the cross-sectional Fit Futures study by the UHPLC-MS/MS method. The following endpoints were used: hypertension (systolic blood pressure over 130 mmHg and/or diastolic blood pressure over 80 mmHg); obesity (body mass index over 2 z-score, WHO charts for adolescents); dyslipidemia (total cholesterol ≥ 5.17 mmol/L, and/or LDL-cholesterol ≥ 3.36 mmol/l, and/or apolipoprotein B ≥ 1.10 g/L).

RESULTS

Perfluorooctane sulfonate (PFOS), perfluorononanoate (PFNA), perfluorodecanoate (PFDA) and perfluoroundecanoate (PFUnDA) serum concentrations were positively associated with apolipoprotein B, total- and LDL cholesterol. The highest vs. lowest quartiles of total PFAS (∑PFAS), PFNA and PFDA concentrations were positively associated with the risk of dyslipidemia: OR 2.24 (95% CI 1.10-4.54), OR 2.30 (95% CI 1.16-4.57) and 2.36 (95% CI 1.08-5.16), respectively. The highest vs. lowest quartiles of ∑PFAS, perfluorohexane sulfonate (PFHxS), PFOS, perfluorooctanoate (PFOA) concentrations were positively associated with the risk of hypertension: OR 1.91 (95% CI 1.12-3.26), OR 2.06 (95% CI 1.16-3.65), 1.86 (95% CI 1.08-3.19) and 2.08 (95% CI 1.17-3.69) respectively. PFHxS and perfluoroheptane sulfonate (PFHpS) concentrations were positively associated with obesity.

CONCLUSIONS

This cross-sectional study showed a possible link between several PFAS and dyslipidemia, hypertension and obesity in Norwegian adolescents.

Differentiating effects of socio-economic factors on relative weight and nutritional status in Polish schoolchildren across intergenerational changes

OBJECTIVE

The aim of this study was an assessment of the effects of urbanisation level, family size and parental education on body mass index (BMI) and mid-upper arm circumference (MUAC) among Polish schoolchildren in cross-sectional surveys conducted between 1966 and 2012.

DESIGN

The analysis involved schoolchildren measured in four Polish Anthropological Surveys (1966, 1978, 1988 and 2012). Socio-economic factors involved: urbanisation level (city, town and village), family size (one child, two children, three children, four or more children), and father's and mother's education (lower and higher education).

SETTING

Regions in Poland - cities: Warsaw, Lodz and Wroclaw; towns: Bystrzyca Klodzka, Pinczow, Siemiatycze, Wolsztyn and their rural surroundings.

PARTICIPANTS

A total sample consisted of 63 757 children (31 774 boys and 31 983 girls) aged 7-18 years.

RESULTS

Between 1966 and 1988, both BMI and MUAC had significantly higher values in children from cities, in families with one child and with higher parental education (P < 0·05). However, MUAC revealed significant differences between particular socio-economic groups more frequently than BMI. In 2012, urbanisation level and parental education ceased to show a differentiating effect on both indicators, while family size remained a significant social factor for both measures (BMI: P < 0·05; MUAC: P < 0·01).

CONCLUSIONS

Since MUAC reflected socio-economic differences more frequently than BMI, it could be a more sensitive and reliable anthropometric measure revealing the effects of socio-economic factors on children's nutritional status.

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.

Endocrine-disrupting chemicals: elucidating our understanding of their role in sex and gender-relevant end points

Endocrine-disrupting chemicals (EDCs) are diverse and pervasive and may have significant consequence for health, including reproductive development and expression of sex-/gender-sensitive parameters. This review chapter discusses what is known about common EDCs and their effects on reproductively relevant end points. It is proposed that one way that EDCs may exert such effects is by altering steroid levels (androgens or 17-estradiol, E₂) and/or intracellular E₂ receptors (ERs) in the hypothalamus and/or hippocampus. Basic research findings that demonstrate developmentally sensitive end points to androgens and E₂ are provided. Furthermore, an approach is suggested to examine differences in EDCs that diverge in their actions at ERs to elucidate their role in sex-/gender-sensitive parameters.