Internal exposure to pollutants and body size in Flemish adolescents and adults: associations and dose-response relationships

Hidden link between endocrine-disrupting chemicals and pediatric obesity

The increasing prevalence of pediatric obesity has emerged as a significant public health concern. Among various contributing factors, exposure to endocrine-disrupting chemicals (EDCs) has gained recognition for its potential role. EDCs, including bisphenols, phthalates, per- and polyfluoroalkyl substances, polycyclic aromatic hydrocarbons, and organochlorines, disrupt hormonal regulation and metabolic processes, contributing to alterations in fat storage, appetite regulation, and insulin sensitivity. This study offers a comprehensive review of the current research linking EDC exposure to pediatric obesity by integrating the findings from experimental and epidemiological studies. It also addresses the complexities of interpreting this evidence in the context of public health, highlighting the urgent need for further research.

As, Cd, Hg, and Pb Biological Concentrations and Anthropometry in Slovak Adolescents

Anthropometry provides a non-invasive technique for evaluating growth and obesity and serves as an indicator of health status. This cross-sectional study aims to investigate the association of internal arsenic (As), cadmium (Cd), total mercury (THg), methylmercury (MeHg), and lead (Pb) exposure with anthropometric parameters, including obesity, in adolescents. Participants (N = 320) were children aged 10-14 years (mean 11.8 years) from eastern Slovakia, at an early stage of adolescence characterized by growth acceleration. Metal concentrations in blood and urine were measured by ICP-MS (for As, Cd, and Pb), GC/ICP-MS (for MeHg) and amalgamation technique AAS (for THg). Median concentrations of the studied elements in whole blood (Cd: 0.16, Pb: 10.6, THg: 0.25, MeHg: 0.11 µg/L) and urine (Cd: 0.25, Pb: 0.73, As: 3.38 µg/g creatinine) were relatively low in our study group. The results showed that blood Cd and Pb concentrations were inversely associated with several anthropometric parameters (body weight, BMI, body fat percentage, chest circumference, and waist circumference) in both boys and girls. Conversely, blood THg concentration was positively associated with these parameters in boys. A positive relationship was also observed between blood MeHg concentration and height in boys, while negative associations between blood Cd and Pb concentrations and height were significant only in girls. No associations were found between metal concentrations (As, Cd, Pb) in urine and parameters of physical growth or obesity. This study demonstrates that even low-level exposure to Cd, Pb, and Hg can influence growth and obesity indicators in adolescents, with distinct sex-specific patterns, highlighting the need for ongoing monitoring and protection against environmental metal exposure.

Obesogens and Energy Homeostasis: Definition, Mechanisms of Action, Exposure, and Adverse Effects on Human Health

BACKGROUND

Obesity is a major risk factor for noncommunicable diseases and is associated with a reduced life expectancy of up to 20 years, as well as with other consequences such as unemployment and increased economic burden for society. It is a multifactorial disease, and physiopathology of obesity involves dysregulated calorie utilization and energy balance, disrupted homeostasis of appetite and satiety, lifestyle factors including sedentary lifestyle, lower socioeconomic status, genetic predisposition, epigenetics, and environmental factors. Some endocrine-disrupting chemicals (EDCs) have been proposed as "obesogens" that stimulate adipogenesis leading to obesity. In this review, definition of obesogens, their adverse effects, underlying mechanisms, and metabolic implications will be updated and discussed.

SUMMARY

Disruption of lipid homeostasis by EDCs involves multiple mechanisms including increase in the number and size of adipocytes, disruption of endocrine-regulated adiposity and metabolism, alteration of hypothalamic regulation of appetite, satiety, food preference and energy balance, and modification of insulin sensitivity in the liver, skeletal muscle, pancreas, gastrointestinal system, and the brain. At a cellular level, obesogens can exert their endocrine disruptive effects by interfering with peroxisome proliferator-activated receptors and steroid receptors. Human exposure to chemical obesogens mainly occurs by ingestion and, to some extent, by inhalation and dermal uptake, usually in an unconscious manner. Persistent pollutants are lipophilic features; thus, they bioaccumulate in adipose tissue.

KEY MESSAGES

Although there are an increasing number of reports studying the effects of obesogens, their mechanisms of action remain to be elucidated. In addition, epidemiological studies are needed in order to evaluate human exposure to obesogens.

Is Environmental Cadmium Exposure Causally Related to Diabetes and Obesity?

Cadmium (Cd) is a pervasive toxic metal, present in most food types, cigarette smoke, and air. Most cells in the body will assimilate Cd, as its charge and ionic radius are similar to the essential metals, iron, zinc, and calcium (Fe, Zn, and Ca). Cd preferentially accumulates in the proximal tubular epithelium of the kidney, and is excreted in urine when these cells die. Thus, excretion of Cd reflects renal accumulation (body burden) and the current toxicity of Cd. The kidney is the only organ other than liver that produces and releases glucose into the circulation. Also, the kidney is responsible for filtration and the re-absorption of glucose. Cd is the least recognized diabetogenic substance although research performed in the 1980s demonstrated the diabetogenic effects of chronic oral Cd administration in neonatal rats. Approximately 10% of the global population are now living with diabetes and over 80% of these are overweight or obese. This association has fueled an intense search for any exogenous chemicals and lifestyle factors that could induce excessive weight gain. However, whilst epidemiological studies have clearly linked diabetes to Cd exposure, this appears to be independent of adiposity. This review highlights Cd exposure sources and levels associated with diabetes type 2 and the mechanisms by which Cd disrupts glucose metabolism. Special emphasis is on roles of the liver and kidney, and cellular stress responses and defenses, involving heme oxygenase-1 and -2 (HO-1 and HO-2). From heme degradation, both HO-1 and HO-2 release Fe, carbon monoxide, and a precursor substrate for producing a potent antioxidant, bilirubin. HO-2 appears to have also anti-diabetic and anti-obese actions. In old age, HO-2 deficient mice display a symptomatic spectrum of human diabetes, including hyperglycemia, insulin resistance, increased fat deposition, and hypertension.

Blood cadmium, lead, manganese, mercury, and selenium levels in American Indian populations: The Strong Heart Study

BACKGROUND

Many American Indian (AI) communities are in areas affected by environmental contamination, such as toxic metals. However, studies assessing exposures in AI communities are limited. We measured blood metals in AI communities to assess historical exposure and identify participant characteristics associated with these levels in the Strong Heart Study (SHS) cohort.

METHOD

Archived blood specimens collected from participants (n = 2014, all participants were 50 years of age and older) in Arizona, Oklahoma, and North and South Dakota during SHS Phase-III (1998-1999) were analyzed for cadmium, lead, manganese, mercury, and selenium using inductively coupled plasma triple quadrupole mass spectrometry. We conducted descriptive analyses for the entire cohort and stratified by selected subgroups, including selected demographics, health behaviors, income, waist circumference, and body mass index. Bivariate associations were conducted to examine associations between blood metal levels and selected socio-demographic and behavioral covariates. Finally, multivariate regression models were used to assess the best model fit that predicted blood metal levels.

FINDINGS

All elements were detected in 100% of study participants, with the exception of mercury (detected in 73% of participants). The SHS population had higher levels of blood cadmium and manganese than the general U.S. population 50 years and older. The median blood mercury in the SHS cohort was at about 30% of the U.S. reference population, potentially due to low fish consumption. Participants in North Dakota and South Dakota had the highest blood cadmium, lead, manganese, and selenium, and the lowest total mercury levels, even after adjusting for covariates. In addition, each of the blood metals was associated with selected demographic, behavioral, income, and/or weight-related factors in multivariate models. These findings will help guide the tribes to develop education, outreach, and strategies to reduce harmful exposures and increase beneficial nutrient intake in these AI communities.

Mitigation of Cadmium Toxicity through Modulation of the Frontline Cellular Stress Response

Cadmium (Cd) is an environmental toxicant of public health significance worldwide. Diet is the main Cd exposure source in the non-occupationally exposed and non-smoking populations. Metal transporters for iron (Fe), zinc (Zn), calcium (Ca), and manganese (Mn) are involved in the assimilation and distribution of Cd to cells throughout the body. Due to an extremely slow elimination rate, most Cd is retained by cells, where it exerts toxicity through its interaction with sulfur-containing ligands, notably the thiol (-SH) functional group of cysteine, glutathione, and many Zn-dependent enzymes and transcription factors. The simultaneous induction of heme oxygenase-1 and the metal-binding protein metallothionein by Cd adversely affected the cellular redox state and caused the dysregulation of Fe, Zn, and copper. Experimental data indicate that Cd causes mitochondrial dysfunction via disrupting the metal homeostasis of this organelle. The present review focuses on the adverse metabolic outcomes of chronic exposure to low-dose Cd. Current epidemiologic data indicate that chronic exposure to Cd raises the risk of type 2 diabetes by several mechanisms, such as increased oxidative stress, inflammation, adipose tissue dysfunction, increased insulin resistance, and dysregulated cellular intermediary metabolism. The cellular stress response mechanisms involving the catabolism of heme, mediated by heme oxygenase-1 and -2 (HO-1 and HO-2), may mitigate the cytotoxicity of Cd. The products of their physiologic heme degradation, bilirubin and carbon monoxide, have antioxidative, anti-inflammatory, and anti-apoptotic properties.

Obesity II: Establishing causal links between chemical exposures and obesity

Obesity is a multifactorial disease with both genetic and environmental components. The prevailing view is that obesity results from an imbalance between energy intake and expenditure caused by overeating and insufficient exercise. We describe another environmental element that can alter the balance between energy intake and energy expenditure: obesogens. Obesogens are a subset of environmental chemicals that act as endocrine disruptors affecting metabolic endpoints. The obesogen hypothesis posits that exposure to endocrine disruptors and other chemicals can alter the development and function of the adipose tissue, liver, pancreas, gastrointestinal tract, and brain, thus changing the set point for control of metabolism. Obesogens can determine how much food is needed to maintain homeostasis and thereby increase the susceptibility to obesity. The most sensitive time for obesogen action is in utero and early childhood, in part via epigenetic programming that can be transmitted to future generations. This review explores the evidence supporting the obesogen hypothesis and highlights knowledge gaps that have prevented widespread acceptance as a contributor to the obesity pandemic. Critically, the obesogen hypothesis changes the narrative from curing obesity to preventing obesity.

Effects of Environmental Exposure to Cadmium and Lead on the Risks of Diabetes and Kidney Dysfunction

Environmental exposure to cadmium (Cd) or lead (Pb) is independently associated with increased risks of type 2 diabetes, and chronic kidney disease. The aim of this study was to examine the effects of concurrent exposure to these toxic metals on the risks of diabetes and kidney functional impairment. The Cd and Pb exposure levels among study subjects were low to moderate, evident from the means for blood concentrations of Cd and Pb ([Cd]_b and [Pb]_b) of 0.59 µg/L and 4.67 µg/dL, respectively. Of 176 study subjects (mean age 60), 71 (40.3%) had abnormally high fasting plasma glucose levels. Based on their [Cd]_b and [Pb]_b, 53, 71, and 52 subjects were assigned to Cd and Pb exposure profiles 1, 2, and 3, respectively. The diagnosis of diabetes was increased by 4.2-fold in those with an exposure profile 3 (p = 0.002), and by 2.9-fold in those with the estimated glomerular filtration (eGFR) ≤ 60 mL/min/1.73 m² (p = 0.029). The prevalence odds ratio (POR) for albuminuria was increased by 5-fold in those with plasma glucose levels above kidney threshold of 180 mg/dL (p = 0.014), and by 3.1-fold in those with low eGFR) (p = 0.050). Collectively, these findings suggest that the Cd and Pb exposure profiles equally impact kidney function and diabetes risk.

The Role of Persistent Organic Pollutants in Obesity: A Review of Laboratory and Epidemiological Studies

Persistent organic pollutants (POPs) are considered as potential obesogens that may affect adipose tissue development and functioning, thus promoting obesity. However, various POPs may have different mechanisms of action. The objective of the present review is to discuss the key mechanisms linking exposure to POPs to adipose tissue dysfunction and obesity. Laboratory data clearly demonstrate that the mechanisms associated with the interference of exposure to POPs with obesity include: (a) dysregulation of adipogenesis regulators (PPARγ and C/EBPα); (b) affinity and binding to nuclear receptors; (c) epigenetic effects; and/or (d) proinflammatory activity. Although in vivo data are generally corroborative of the in vitro results, studies in living organisms have shown that the impact of POPs on adipogenesis is affected by biological factors such as sex, age, and period of exposure. Epidemiological data demonstrate a significant association between exposure to POPs and obesity and obesity-associated metabolic disturbances (e.g., type 2 diabetes mellitus and metabolic syndrome), although the existing data are considered insufficient. In conclusion, both laboratory and epidemiological data underline the significant role of POPs as environmental obesogens. However, further studies are required to better characterize both the mechanisms and the dose/concentration-response effects of exposure to POPs in the development of obesity and other metabolic diseases.

Biomonitoring of Exposure to Metals in a Population Residing in an Industrial Area in Brazil: A Feasibility Study

Background: Industries are sources of environmental pollutants. However, there are few human biomonitoring (HBM) studies in the vicinity of industrial areas. Thus, we evaluate the feasibility of conducting an HBM study to assess exposure to metals in an industrial area in Rio de Janeiro, Brazil. Methodology: A cross-sectional survey was conducted near a steel factory. Adults (exposed = 775; controls = 775) were randomly selected and sex-matched. Subjects were interviewed using a questionnaire and a 24 h dietary recall. Blood samples were collected to analyze metal concentrations, blood count, biochemical parameters, and thyroid hormones. The feasibility of the survey was assessed following guidelines. The descriptive analysis was performed for the first 250 participants (pilot study). Results: Adjustments were made to the survey execution, including age-matching, fieldwork team, questionnaire, blood collection, and research awareness. The complete questionnaire was answered by ≥97% of participants; metals were measured in ≥98% and clinical parameters in ≥89%, except thyroid hormones (13–44%). The average age and family income were of 50 years and USD 575/month, respectively. The participants had equal distribution among sexes: 50% had a medium education level, and 59% were nonwhite. Conclusion: This preliminary HBM study demonstrates feasibility for the total population, with results indicating representativeness of the target population.

Epigenetic Mechanisms of Endocrine-Disrupting Chemicals in Obesity

The incidence of obesity has dramatically increased over the last decades. Recently, there has been a growing interest in the possible association between the pandemics of obesity and some endocrine-disrupting chemicals (EDCs), termed “obesogens”. These are a heterogeneous group of exogenous compounds that can interfere in the endocrine regulation of energy metabolism and adipose tissue structure. Oral intake, inhalation, and dermal absorption represent the major sources of human exposure to these EDCs. Recently, epigenetic changes such as the methylation of cytosine residues on DNA, post-translational modification of histones, and microRNA expression have been considered to act as an intermediary between deleterious effects of EDCs and obesity development in susceptible individuals. Specifically, EDCs exposure during early-life development can detrimentally affect individuals via inducing epigenetic modifications that can permanently change the epigenome in the germline, enabling changes to be transmitted to the next generations and predisposing them to a multitude of diseases. The purpose of this review is to analyze the epigenetic alterations putatively induced by chemical exposures and their ability to interfere with the control of energy metabolism and adipose tissue regulation, resulting in imbalances in the control of body weight, which can lead to obesity.

Potential obesogenic effect of a complex contaminant mixture on Cree First Nations adults of Northern Québec, Canada

BACKGROUND

Obesity incidence and prevalence is of increasing concern in First Nations communities around Canada. In addition to diet and physical activity, environmental pollutants have been suggested as a potential contributory factor to obesity associated morbidity. Owing to the exposure of Cree First Nations people to various persistent organic pollutants (POPs) and toxic metals, it is important to examine the association between obesity in these communities, and contaminant body burdens.

OBJECTIVE

To determine whether selected morphometry measures (body mass index [BMI], waist circumference [WC] and body fat percentage) are associated with body burdens of 10 POPs and toxic metals.

METHODS

Using data from the Nituuchischaayihtitaau Aschii Multi-community Environment-and-Health study in the eastern James Bay (Eeyou Istchee) Cree communities, this cross-sectional study examined morphometric and contaminant measures of 695 eligible participants. Sex stratified principal component analysis was conducted on blood plasma concentrations of 10 POPs and toxic metals. BMI, WC, body fat percent, and resultant contaminant components were used to create generalized linear models, and adjusted for covariates (age, total lipids, smoking, and n-3 fatty acids).

RESULTS

Two principal components (PCs; PC-1 and PC-2) were extracted for both males and females. For females, PC-1 explained 73.3% and PC-2 explained 10.5%, and for males, PC-1 explained 71.6% and PC-2 explained 11.2% of the variance in contaminant burden. For both sexes, PC-1 loaded highly for polychlorinated biphenyl (PCB) congeners, organochlorine pesticides and, to a lesser extent, mercury and lead. PC-2 loaded highly for cadmium for females, and cadmium and lead for males. After adjusting for covariates, the generalized linear model showed that PC-2 was significantly and negatively associated with BMI, body fat percent, and WC in males and females.

CONCLUSIONS

Our cross-sectional analysis indicates a negative association between cadmium with various obesity measures in both males and females. Null associations were found between PCBs and organochlorine pesticides and morphometry.

Concentration of polychlorinated biphenyls in serum from New Jersey biomonitoring study: 2016-2018

The first statewide New Jersey Biomonitoring (NJBM) of serum polychlorinated biphenyls (PCBs) was conducted from 2016 to 2018. Forty ortho-substituted PCBs were measured in serum samples collected from 920 NJ residents in compliance with the CDC method. The lipid adjusted geometric mean (GM) of ∑₄₀PCB concentration for all the 920 measured subjects was 65.5 ng/g lipid (95% CIs: 56.9-75.4 ng/g lipid). Age stratified serum concentration showed that the lowest GM (33.3 ng/g lipid) was observed in the 20-39 years age group (n = 282), followed by a concentration of 76.05 ng/g lipid (n = 382) in the 40-59 years age group, and the highest GM (168.4 ng/g lipid) was found in the 60-74 years age group (n = 256). A survey regression model revealed that ∑₄₀PCBs was significantly associated with age, moderately associated with geographic region, and not significantly associated with sex. The comparison of serum PCB levels in NJBM with the sequential National Health and Nutrition Examination Survey (NHANES) data suggested that the serum PCBs in NJ adults declined 52-59% at all age groups over the last decade. Positive Matrix Factorization (PMF) suggests that ongoing and recent exposure to lower molecular weight PCBs contributes about 15% to total serum PCB levels and more in younger subjects, while higher molecular weight PCBs contribute 52% of the total serum PCB levels and more in older subjects.

Environment-wide association study on childhood obesity in the U.S

BACKGROUND

Childhood obesity is a national public health issue with increasing prevalence. It has been linked to diet, lack of physical activity, and genetic susceptibility, with more recent evidence that it could also result from environmental factors. Studies linking it to environmental factors are limited, unsystematic, incomprehensive, and inconclusive.

OBJECTIVE

To conduct an environment-wide association study (EWAS) to comprehensively investigate all the environmental factors available in a nationally representative sample of children to determine factors associated with childhood obesity.

METHODS

We utilized the 1999-2016 National Health and Nutrition Examination Survey (NHANES) datasets and included all children/adolescents (6-17 years). Obesity was measured using body mass index and waist to height ratio. A multinomial and binary logistic regression were used adjusting for age, sex, race/ethnicity, creatinine, calorie intake, physical activity, screen time, limitation to physical activities, and socioeconomic status. We then controlled for multiple hypothesis testing and validated our findings on a different cohort of children.

RESULTS

We found that metals such as beryllium (OR: 3.305 CI: 1.460-7.479) and platinum (OR: 1.346 CI: 1.107-1.636); vitamins such as gamma-tocopherol (OR: 8.297 CI: 5.683-12.114) and delta-tocopherol (OR: 1.841 CI:1.476-2.297); heterocyclic aromatic amines such as 2-Amino-9H-pyrido (2,3-b) indole (OR: 1.323 CI: 1.083-1.617) and 2-Amino-3-methyl-9H-pyriodo(2,3-b)indole (OR: 2.799 CI: 1.442-5.433); polycyclic aromatic amines such as 9- fluorene (OR: 1.509 CI: 1.230-1.851) and 4-phenanthrene (OR: 2.828 CI: 1.632-4.899); and caffeine metabolites such as 1,3,7-trimethyluric acid (OR: 1.22 CI: 1.029-1.414) and 1,3,7-trimethylxanthine (OR: 1.258 CI: 1.075-1.473) were positively and significantly associated with childhood obesity.

CONCLUSION

Following the unique concept of EWAS, certain environmental factors were associated with childhood obesity. Further studies are required to confirm these associations while investigating their mechanisms of action.

Effects of polychlorinated biphenyls exposure on physical growth from birth to childhood and adolescence: A prospective cohort study

BACKGROUND/AIMS

Given that their traditional lifestyle and diet still relies on fish and other marine species for sustenance, the Inuit are highly exposed to polychlorinated biphenyls (PCBs) and PCBs are increasingly linked to obesity. However, evidence is not consistent regarding which periods of exposure are most relevant. In this study, we examine whether in utero, childhood, and adolescent exposure to PCBs are related to physical growth at adolescence.

METHOD

Inuit adolescents from Canada (N=212) enrolled in a prospective longitudinal cohort study since birth were assessed for height, weight, body mass index (BMI), fat mass index (FMI) and fat free mass index (FFMI) at 18 years of age. PCB 153 concentrations were quantified in blood samples obtained at birth (umbilical cord), 11, and 18 years of age. Maternal anthropometrics were measured and those for the newborns collected from medical records. Data on biological mothers and participants' sociodemographic characteristics and food security were collected using interviews. Multiple linear regression analyses were used to test associations between PCB 153 concentrations and adolescent anthropometric measures.

RESULTS

Cord PCB 153 was not related to height or FFMI at adolescence. By contrast, analyses showed that cord PCB 153 was related to higher BMI, FMI and marginally to weight in girls but not boys. Child PCB 153 was not related to height, weight or FFMI in adolescence. Child PCB 153 was related to lower BMI and FMI at adolescence in both sexes, particularly among those considered overweight or obese during childhood. Adolescent PCB 153 was not associated with any outcome.

CONCLUSION

This study suggests that prenatal exposure to PCBs may have a long-term effect on growth in early adulthood among girls and identifies the peri-pubertal period as another window of sensitivity for the action of PCBs. Our findings also suggest that exposure to PCBs and body size be documented in multiple time periods from infancy to adulthood.

Exposure to endocrine-disrupting chemicals and anthropometric measures of obesity: a systematic review and meta-analysis

OBJECTIVE

Endocrine-disrupting chemicals (EDCs) are viewed as a major potential link between the environment and obesity development. We did a systematic review and meta-analysis to examine the association between exposure to EDCs and obesity.

DATA SOURCES, DESIGN AND ELIGIBILITY CRITERIA

PubMed, Scopus and Web of Science were searched from inception to 6 June 2018 for studies primarily addressing the association between exposure to EDCs after the age of 2 years and anthropometric measures of obesity or body fat. The Newcastle-Ottawa scale was used to assess the risk of bias.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers screened and conducted data extraction and synthesis. A third reviewer resolved disagreements.

RESULTS

A total of 73 studies investigating bisphenol A (32 286 individuals), organochlorine compounds (34 567 individuals), phthalates (21 401 individuals), polybrominated biphenyls (2937 individuals), polycyclic aromatic hydrocarbons (5174 individuals), parabens (4097 individuals), benzoic acid (3671 individuals) and polyfluoroalkyl substances (349 individuals) met our inclusion criteria. Most had a cross-sectional design and low or medium risk of bias. In qualitative analysis, bisphenol A and phthalates were consistently associated with general and abdominal obesity, in children and adults, and some studies suggested this association was age-dependent and gender-dependent. Meta-analysis indicated a significant association between exposure to bisphenol A and overweight (OR 1.254, 95% CI 1.005 to 1.564), obesity (OR 1.503, 95% CI 1.273 to 1.774) and increased waist circumference (OR 1.503, 95% CI 1.267 to 1.783) in adults, and between exposure to 2,5-dichlorophenol and obesity in children (OR 1.8, 95% CI 1.1018 to 3.184).

CONCLUSION

Most observational studies supported a positive association between obesity and exposure to EDCs. Although causality cannot be determined from these data, they underscore the need to limit human exposure to EDCs in light of the evidence from animal and cell-based studies indicating the effects of these chemicals on adiposity.

PROSPERO REGISTRATION NUMBER

CRD42018074548.

Public health issues from crude-oil production in the Ecuadorian Amazon territories

Crude oil production (COP) is a high-pollution industry but the vast Amazon rainforest has been an active COP zone for South America. Although COP has been associated with a variety of health effects among workers around the world, such effects have not been adequately investigated in the Amazon region, especially at the community level. Therefore, this review was conducted to provide a report about COP in the Amazon of Ecuador and about its association with health status of indigenous human populations. Some epidemiological surveys in the Amazonian Territories indicate that COP has been associated with health problems in the surrounding populations, e.g. cancers in the stomach, rectum, skin, soft tissue, kidney and cervix in adults, and leukemia in children. In addition, some biomarkers and mechanistic studies show exposure effects. However, due to limitations from these studies, contradictory associations have been reported. Our review indicates that COP in the Amazonian territories of northern Ecuador was characterised by contamination which could have affected the indigenous and non-indigenous populations. However, there have not been dedicated investigations to provide relationships between the contamination and the subsequent exposure-health effects. Since indigenous populations have different lifestyle and cultures from regular city dwellers, systematic studies on their potential health hazards need to be conducted. Due to the remote locations and sparse populations, these new studies may involve the use of novel and genomic-based biomarkers as well as using high technology in the remote regions.

Urinary cadmium and timing of menarche and pubertal development in girls

BACKGROUND

Cadmium (Cd) is a developmental toxicant that is released into the environment during industrial processes. Previous animal studies suggest that Cd may impact the onset of puberty.

OBJECTIVES

To determine whether Cd exposure, measured as urinary Cd concentration, was associated with ages at menarche and pubertal development.

METHODS

A cohort of 211 girls, ages 10-13 years at baseline, was followed for up to two years. Girls completed an interview and self-assessment of Tanner stages of breast development and pubic hair growth. They were followed monthly until menarche. Urinary Cd concentrations were measured in overnight urine specimens. Multivariable Cox regression was used to evaluate the association between urinary Cd and age at menarche and cumulative logit regression was used to evaluate the associations between urinary Cd and breast development and pubic hair growth.

RESULTS

The baseline geometric mean creatinine-adjusted Cd concentration was 0.22 μg/g creatinine (geometric standard deviation = 1.6) and decreased with increasing age (p-trend = 0.04). Cd levels were higher among Asian than White girls or girls of other/mixed race/ethnicity (p = 0.04). In multivariable analyses, girls with urinary Cd ≥ 0.4 μg/L were less likely to have attained menarche than girls with urinary Cd < 0.2 μg/L (hazard ratio = 0.42; 95% confidence interval, 0.23-0.78). Urinary Cd was negatively associated with pubic hair growth (p-trend = 0.01) but not with breast development (p-trend = 0.72) at baseline.

CONCLUSIONS

These findings suggest that a higher Cd body burden may delay some aspects of pubertal development among girls.

Where are we at with lead? Current levels, time trend, and determinants of blood lead in New Zealand children and adults

AIMS

A national biomonitoring survey was conducted in 2014-2016, to determine current blood lead levels (BLL) in New Zealand children and adults and identify determinants of BLL.

METHODS

Blood samples were provided by 191 children (age 5-18) and 304 adults (age 20-65) and analysed for BLL using inductively coupled mass spectroscopy. Linear regression on log-transformed BLL was used to assess associations between BLL and demographic and lifestyle factors collected via questionnaire.

RESULTS

The geometric mean (GM) BLL was 0.86 μg/dl (95%CI 0.80-0.92) for children and 1.31 μg/dl (1.23-1.39) for adults, representing a 90% reduction in BLL over the past 36 years. For children, shellfish consumption was associated with 20% higher BLL. Adult BLLs were positively associated with age, beer consumption, spirits consumption, having roof water as the home's water supply, and having worked in glass manufacturing. Determinants of reduced BLL were tofu and canned food consumption. For women, menopause was associated with 34% higher BLL.

CONCLUSIONS

Although significant reductions in New Zealanders' BLL have been achieved in the past decades, this study identified several additional opportunities to reduce further background exposure to lead. In particular, consideration needs to be given to reducing lead levels in New Zealand roof water supplies.

A review of the evidence to support interim reference level for dietary lead exposure in adults

FDA developed the interim reference level (IRL) for lead of 3 μg/day in children and 12.5 μg/day in women of childbearing age (WOCBA) to better protect the fetus from lead toxicity. These IRLs correspond to a blood lead level (BLL) of 0.5 μg/dL in both populations. The current investigation was performed to determine if the IRL for WOCBA should apply to the general population of adults. A literature review of epidemiological studies was conducted to determine whether a BLL of 0.5 μg/dL is associated with adverse effects in adults. Some studies reported adverse effects over a wide range of BLLs that included 0.5 μg/dL adding uncertainty to conclusions about effects at 0.5 μg/dL; however, no studies clearly identified this BLL as an adverse effect level. Results also showed that the previously developed PTTDI for adults of 75 μg/day lead may not be health protective, supporting use of a lower reference value for lead toxicity in this population group. Use of the 12.5 μg/day IRL as a benchmark for dietary lead intake is one way FDA will ensure that dietary lead intake in adults is reduced.

Longitudinal study of age of menarche in association with childhood concentrations of persistent organic pollutants

BACKGROUND

Age at female puberty is associated with adult morbidities, including breast cancer and diabetes. Hormonally active chemicals are suspected of altering pubertal timing. We examined whether persistent organic pollutants (POPs) are associated with age at menarche in a longitudinal study.

METHODS

We analyzed data for females enrolled at age 6-8 years in the Breast Cancer and Environment Research Program from California and Ohio. Participants were followed annually 2004-2013 and provided serum (mean age 7.8 years) for measurement of polychlorinated biphenyl (PCB), organochlorine pesticide (OCP), and polybrominated diphenyl ether (PBDE) concentrations. Age of menarche was assigned based on parental and participant reported dates and ages of menarche. Adjusted hazard ratios (aHRs) for menarchal onset were calculated with Cox proportional regression. Body mass index (BMI), potentially on the causal pathway, was added to parallel analyses.

RESULTS

Age of menarche was later with higher summed PCB levels (median 11.9 years in quartile 1 [Q1] versus 12.7 in quartile 4 [Q4]) and OCP levels (12.1 years versus 12.4, respectively). When adjusting for all covariates except BMI, higher POP concentrations were associated with later age at menarche (Q4 versus Q1 aHRs: PBDEs 0.75 [95% CI 0.58, 0.97], PCBs 0.67 [95% CI 0.5, 0.89], and OCPs 0.66 [95% CI 0.50, 0.89]). Additional adjustment for BMI attenuated aHRs; PCB aHR approached the null.

CONCLUSION

Findings revealed later onset of menarche with higher concentrations of certain POPs, possibly through an association with BMI. Altered pubertal timing may have long lasting effects on reproductive health and disease risk, so continued attention is important for understanding the biological processes affected by hormonally active chemicals.

[Exposure to metals in the adult population living in industrial areas: a systematic review of the literature]

This study aimed to review studies of human biomonitoring (HBM) that evaluated exposure to lead (Pb), cadmium (Cd), mercury (Hg), nickel (Ni), arsenic (As) and manganese (Mn) in adults living close to industrial areas. A systematic review of studies was selected, without initial date limit through to December 2017, from the MEDLINE and BVS databases. Original studies in English, Portuguese or Spanish conducted among the adult population using blood and/or urine as biomarkers were included. The articles were evaluated according to methodological criteria, including studies with comparison groups and/or probabilistic sampling. Of the 28 studies selected, 54% were conducted in Europe, 36% in Asia, 7% in North America and 4% in Africa. Foundries, metal works and steel mills were the most frequently studied. Urine and blood were used in 82% and 50% of studies, respectively. The elements most investigated were Cd, Pb and As. Despite using heterogeneous methodologies, the results revealed higher metal concentrations, especially from As and Hg in general, than in the comparison group. This review highlights the need for more rigorous methodological studies of HBM, stressing the importance of public health vigilance among populations exposed to toxic metals, especially in developing countries.

Prenatal Cadmium Exposure Is Negatively Associated With Adiposity in Girls Not Boys During Adolescence

Introduction: Cadmium is a pervasive toxic metal that remains a public health concern and exposure in early life has been associated with growth deficits in infancy and childhood. Growth during adolescence also may be sensitive to effects of cadmium exposure, given the changes in distribution of lean and adipose tissue that vary by sex during puberty. This study examines whether prenatal and concurrent cadmium exposures are associated with adiposity measures at ages 8-15 years in a well-characterized birth cohort. Methods: The sample included 185 participants from the ELEMENT birth cohorts in Mexico City with complete data on urinary cadmium exposures, anthropometry and covariates [child age and sex, household socioeconomic status, and maternal smoking history and body mass index (BMI)]. Maternal third trimester and adolescent urines were analyzed for cadmium using an Inductively Coupled Plasma Mass Spectrometer. Trained personnel obtained anthropometry including height, weight, waist circumference and subscapular, suprailiac, and triceps skinfold thickness. BMI z-scores for age and sex were calculated using the World Health Organization's reference standard. Linear regression models were used to estimate the association of prenatal and concurrent urinary cadmium levels with adolescent anthropometry, adjusting for covariates. Results: Among 87 males and 98 females, median age was 10 years (IQR 9 -11 years). Pregnant women and children had median urinary cadmium concentrations of 0.19 μg/L (IQR 0.12- 0.27 μg/L) and 0.14 μg/L (IQR 0.11- 0.18 μg/L), respectively. Regression models showed inverse relationships between prenatal cadmium exposure and adolescent adiposity. An IQR increase in prenatal cadmium was associated with percent decreases in BMI z-score (-27%, p = 0.01), waist circumference (-3%, p = 0.01), and subscapular (-11%, p = 0.01), suprailiac (-11%, p = 0.02), and triceps (-8%, p < 0.01) skinfold thickness. When stratified by sex, these relationships remained statistically significant in females but not males. Conclusions: Prenatal cadmium exposure was negatively associated with measures of both abdominal and peripheral adiposity in girls, but not in boys. These results emphasize the sex-dependent effects of in utero cadmium exposure on adiposity in adolescence.

Joint effects of chronic exposure to environmentally relevant levels of nonylphenol and cadmium on the reproductive functions in male rockfish Sebastiscus marmoratus

Nonylphenol (NP) and Cadmium (Cd) are two common contaminants that can be detected in aquatic environments. Nevertheless, the combined toxicity of NP and Cd at environmentally relevant concentrations in aquatic organisms has not been thoroughly characterized to date. In the present study, the interactions between NP and Cd on male Sebastiscus marmoratus were studied. After 21 days of exposure, the brain aromatase activity was observed to be significantly induced by 100 ng/L NP and 40 μg/L Cd, whereas all of the concentrations of co-treatment resulted in an increase in brain aromatase activity. Additionally, NP could also reduce plasma testosterone concentration, while NP, Cd and their mixture could induce plasma 17β-estradiol (E2) concentration and VTG concentration. The interactions between NP and Cd on the reproductive physiology were antagonism. Our results also support the notion of using these indicators as biomarkers for exposure to EDCs and further extend the boundary of biomonitoring to environmental levels.

Obesity in relation to serum persistent organic pollutant concentrations in CHAMACOS women

BACKGROUND

Environmental exposure to endocrine-disrupting chemicals (EDCs), including persistent organic pollutants (POPs), has been hypothesized to increase risk of obesity. Using data from the Center for Health Assessment of Mothers and Children of Salinas (CHAMACOS) study, we examined the longitudinal relationship between serum concentrations of a POPs mixture and several obesity measures.

METHODS

Concentrations of 17 POPs were measured in serum collected in 2009-2011 from 468 CHAMACOS women. Anthropometry measurements and personal interviews were completed at up to three study visits between 2009 and 2014. We assessed the relationship of serum POPs concentrations with adiposity measures longitudinally using generalized estimating equation (GEE) models. We implemented Bayesian Kernel Machine Regression (BKMR) to elucidate the effects of joint exposure to the POPs mixture.

RESULTS

In GEE models, positive associations with BMI were found for dichlorodiphenyltrichloroethane (Q4 vs Q1: adjusted-β = 3.2 kg/m2; 95%CI 1.5,4.9), β-hexachlorocyclohexane (Q4 vs Q1: adjusted-β = 3.6 kg/m2; 95%CI 2.0,5.2), and PBDE-47 (Q4 vs Q1: adjusted-β = 1.9 kg/m2; 95%CI 0.3,3.5), while PBDE-153 was inversely associated (Q4 vs Q1: adjusted-β = -2.8 kg/m2; 95%CI -4.4,-1.2). BKMR results, while largely consistent with single pollutant models, revealed the shape and direction of the exposure-response relationships, as well as interactions among pollutants within the mixture, that could not be discovered by single-pollutant models.

CONCLUSION

In summary, we found significant associations of serum POPs with several adiposity measures using both conventional regressions and BKMR. Our results provide support for the chemical obesogen hypothesis, that exposure to EDCs may alter risk for later obesity.

Hair concentration of trace elements and growth in homeless children aged <6years: Results from the ENFAMS study

BACKGROUND

Growth is an important indicator of health in early childhood. This is a critical developmental period, during which a number of factors, including exposure to metals, might play a role in later physical and metabolic functions.

OBJECTIVE

To study the association between exposure to arsenic (As), cadmium (Cd), mercury (Hg), lead (Pb) and selenium (Se), and physical growth of children from homeless families aged <6years.

METHODS

This study was based on data of the cross-sectional survey (ENFAMS), which was conducted by the Observatoire du Samu Social on a random sample of homeless sheltered families in the Paris region during winter 2013. Families with children under 6years (N=324) were interviewed in 17 languages using face-to-face questionnaires. A nurse took anthropometric measures and collected hair samples where As, Cd, Hg, Pb and Se levels were measured. We calculated weight-for-age Z-score (WAZ), height-for-age Z-score (HAZ) and BMI-for-age Z-score (BMIZ) of children, using the 2006 WHO Child Growth Standards as a reference. Associations between ln-transformed metal exposures and growth outcomes were tested by multivariable linear regression models with adjustment for potential confounders (including maternal anthropometrical and socio-demographical characteristics, gestational age, child birthweight, breastfeeding, food insecurity of the child). Due to missing data (1.6% to 14.2% depending on the variables), we used multiple imputation by chained equations.

RESULTS

A strong positive correlation was found between Pb and Cd levels (r=0.65; p<0.001). Positive associations between Se level and HAZ (β=0.61; p=0.05) and between Cd and BMIZ (β=0.21; p=0.03) and negative associations between As and HAZ (β=-0.18; p=0.05) were no more significant after multiple imputation. A weak negative trend was observed between Cd and HAZ (β=-0.14; p=0.14), while positive trends were found between Se and both WAZ (β=0.55; p=0.10) and HAZ (β=0.51; p=0.06) after multiple imputation.

CONCLUSION

Overall, our results found no strong association between exposure to metals and physical growth of homeless children but we observed some trends that were consistent with previous studies. More research is required studying these associations longitudinally, along with higher sample sizes, for better understanding the sources of exposure in homeless population and the potential effects on growth.

Dietary Cadmium Intake and Its Effects on Kidneys

Cadmium (Cd) is a food-chain contaminant that has high rates of soil-to-plant transference. This phenomenon makes dietary Cd intake unavoidable. Although long-term Cd intake impacts many organ systems, the kidney has long been considered to be a critical target of its toxicity. This review addresses how measurements of Cd intake levels and its effects on kidneys have traditionally been made. These measurements underpin the derivation of our current toxicity threshold limit and tolerable intake levels for Cd. The metal transporters that mediate absorption of Cd in the gastrointestinal tract are summarized together with glomerular filtration of Cd and its sequestration by the kidneys. The contribution of age differences, gender, and smoking status to Cd accumulation in lungs, liver, and kidneys are highlighted. The basis for use of urinary Cd excretion to reflect body burden is discussed together with the use of urinary N-acetyl-β-d-glucosaminidase (NAG) and β2-microglobulin (β2-MG) levels to quantify its toxicity. The associations of Cd with the development of chronic kidney disease and hypertension, reduced weight gain, and zinc reabsorption are highlighted. In addition, the review addresses how urinary Cd threshold levels have been derived from human population data and their utility as a warning sign of impending kidney malfunction.

Determinants of serum organochlorine pesticide and polychlorinated biphenyl levels in middle-aged Korean adults

The serum levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were measured in a middle-aged Korean population and investigated associations with age, gender, body mass index (BMI), metabolic syndrome (MS), type 2 diabetes mellitus (T2DM), and dietary habits. The median concentrations of 22 OCPs and 34 PCBs in the serum samples were 483 and 216 ng g^-1 lipid, respectively. The most abundant compound was p,p'-DDE, followed by PCB 153, β-HCH, PCB 118, and PCB 180. The results of multiple linear regression and other statistical analyses revealed that serum OCP and PCB levels were higher in women and were positively correlated with age. BMI was positively associated with serum OCP and PCB levels, reflecting the influence of food intake and the preserving effect of body fat. MS and T2DM were significantly associated with serum OCP and PCB levels. The intake of animal foods had positive associations with serum OCP and PCB levels, whereas the intake of phytogenic foods showed negative associations, presumably because of contamination levels in food items and food matrices that governs absorption and excretion of OCPs and PCBs in the body. The relationship between dietary habits and serum OCP and PCB levels were different in participants with MS compared to healthy participants, suggesting MS may alter the influence of food intake on serum OCP and PCB levels.

Links between Dietary Protein Sources, the Gut Microbiota, and Obesity

The association between the gut microbiota and obesity is well documented in both humans and in animal models. It is also demonstrated that dietary factors can change the gut microbiota composition and obesity development. However, knowledge of how diet, metabolism and gut microbiota mutually interact and modulate energy metabolism and obesity development is still limited. Epidemiological studies indicate an association between intake of certain dietary protein sources and obesity. Animal studies confirm that different protein sources vary in their ability to either prevent or induce obesity. Different sources of protein such as beans, vegetables, dairy, seafood, and meat differ in amino acid composition. Further, the type and level of other factors, such as fatty acids and persistent organic pollutants (POPs) vary between dietary protein sources. All these factors can modulate the composition of the gut microbiota and may thereby influence their obesogenic properties. This review summarizes evidence of how different protein sources affect energy efficiency, obesity development, and the gut microbiota, linking protein-dependent changes in the gut microbiota with obesity.

Adipose Tissue as a Site of Toxin Accumulation

We examine the role of adipose tissue, typically considered an energy storage site, as a potential site of toxicant accumulation. Although the production of most persistent organic pollutants (POPs) was banned years ago, these toxicants persist in the environment due to their resistance to biodegradation and widespread distribution in various environmental forms (e.g., vapor, sediment, and water). As a result, human exposure to these toxicants is inevitable. Largely due to their lipophilicity, POPs bioaccumulate in adipose tissue, resulting in greater body burdens of these environmental toxicants with obesity. POPs of major concern include polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and furans (PCDDs/PCDFs), and polybrominated biphenyls and diphenyl ethers (PBBs/PBDEs), among other organic compounds. In this review, we (i) highlight the physical characteristics of toxicants that enable them to partition into and remain stored in adipose tissue, (ii) discuss the specific mechanisms of action by which these toxicants act to influence adipocyte function, and (iii) review associations between POP exposures and the development of obesity and diabetes. An area of controversy relates to the relative potential beneficial versus hazardous health effects of toxicant sequestration in adipose tissue. © 2017 American Physiological Society. Compr Physiol 7:1085-1135, 2017.

Peripubertal blood lead levels and growth among Russian boys

BACKGROUND

Childhood blood lead levels (BLL) have been associated with growth impairment.

OBJECTIVES

We assessed associations of peripubertal BLL with adolescent growth and near adult height in a longitudinal cohort of Russian boys.

METHODS

481 boys were enrolled at ages 8-9years and followed annually to age 18. At enrollment, BLL was measured, and height, weight, and pubertal staging were obtained annually during 10years of follow-up. Mixed effects models were used to assess the associations of BLL with longitudinal age-adjusted World Health OrganizationZ-scores for height (HT-Z) and body mass index (BMI-Z), and annual height velocity (HV). Interactions between boys' age and BLL on growth outcomes were evaluated.

RESULTS

The median (range) BLL was 3.0 (0.5-31.0) μg/dL. At age 18years, 79% of boys had achieved near adult height (HV <1.0cm/year), and means (SD) for HT-Z and BMI-Z were 0.15 (0.92) and -0.32 (1.24). Over 10years of follow-up, after covariate adjustment, boys with higher (≥5μg/dL) BLL compared with lower BLL were shorter (adjusted mean difference in HT-Z=-0.43, 95% CI -0.60, -0.25, p-value <0.001), translating to a 2.5cm lower height at age 18years. The decrement in height for boys with higher BLL was most pronounced at 12 to 15years of age (interaction p=0.03). Boys with higher BLL were leaner (adjusted mean difference in BMI-Z=-0.22, 95% CI: -0.45, 0.01, p=0.06).

CONCLUSIONS

Higher peripubertal BLLs were associated with shorter height through age 18years, suggesting a persistent effect of lead on linear growth.

Low-Level Toxic Metal Exposure in Healthy Weaning-Age Infants: Association with Growth, Dietary Intake, and Iron Deficiency

Even low levels of toxic metal exposure (As, Cd, Hg, and Pb) in infancy might be harmful to children's development. This study investigated toxic metal exposure on healthy weaning-age infants and its relationship with growth, diet, and iron/anemia status. The weight, height, head circumference, whole blood levels of four toxic metals, hemoglobin, and serum ferritin of healthy infants was measured. Among 210 infants with a median age of 11.4 months (interquartile range: 10.5-12.0), the median levels of As, Cd, Hg, and Pb were 1.2 μg/L, 0.05 μg/L, 0.8 μg/L, and 0.83 μg/dL, respectively. In adjusted linear regression models, post-birth weight gain (Pb) and current head circumference (As, Pb) were negatively associated with toxic metal levels. In multiple linear regression or logistic regression analysis, the duration of breastfeeding (all four metals), perceived adequacy of rice-based food intake (As), regular fish intake (As, Hg), and iron deficiency with/without anemia (Cd, Pb) were associated with increased toxic metal levels. Although levels of toxic metals may not usually be high in this population, individual exposure risk may need to be assessed after considering the type of feeding or intake of complementary foods and the iron/anemia status while evaluating growth status during late infancy.

Serum polychlorinated biphenyls and their hydroxylated metabolites are associated with demographic and behavioral factors in children and mothers

Factors contributing to the inter-individual variation in body burden of polychlorinated biphenyls (PCBs) and their hydroxylated metabolites (OH-PCBs) have not been fully elucidated. We examined associations between total serum concentrations of 209 PCBs, 64 OH-PCBs, and frequently detected individual congeners with demographic characteristics (age, gender, ethnicity and community of residence), body mass index (BMI or BMI percentile), and breastfeeding history in children and their mothers from 83 U.S. households. There was a significant positive association between age and concentrations of total PCBs and OH-PCBs in mothers. Non-Hispanics had significantly higher concentrations of total PCBs in mothers and OH-PCBs in children than Hispanics. Concentrations of total PCBs were significantly lower in mothers who had longer breastfeeding duration. Living in the Columbus Junction, Iowa community as compared to East Chicago, Indiana was associated with higher total PCBs in children, probably attributable to higher exposures at school. Lower concentrations of OH-PCBs were significantly associated with a higher BMI percentile in children. Congener-specific associations were observed for 30 PCB and 12 OH-PCB congeners and followed comparable trends. To our knowledge, this is the first study to examine factors contributing to variations in serum concentrations of total 209 PCBs and total OH-PCBs in children, as well as to examine ethnic differences in OH-PCB levels. Results from this study revealed that demographic characteristics, body mass index and breastfeeding history are factors that should be considered for human exposure and risk assessment of PCBs and OH-PCBs.

Polychlorinated biphenyls and links to cardiovascular disease

The pathology of cardiovascular disease is multi-faceted, with links to many modifiable and non-modifiable risk factors. Epidemiological evidence now implicates exposure to persistent organic pollutants, such as polychlorinated biphenyls (PCBs), with an increased risk of developing diabetes, hypertension, and obesity; all of which are clinically relevant to the onset and progression of cardiovascular disease. PCBs exert their cardiovascular toxicity either directly or indirectly via multiple mechanisms, which are highly dependent on the type and concentration of PCBs present. However, many PCBs may modulate cellular signaling pathways leading to common detrimental outcomes including induction of chronic oxidative stress, inflammation, and endocrine disruption. With the abundance of potential toxic pollutants increasing globally, it is critical to identify sensible means of decreasing associated disease risks. Emerging evidence now implicates a protective role of lifestyle modifications such as increased exercise and/or nutritional modulation via anti-inflammatory foods, which may help to decrease the vascular toxicity of PCBs. This review will outline the current state of knowledge linking coplanar and non-coplanar PCBs to cardiovascular disease and describe the possible molecular mechanism of this association.

Abdominal Obesity and Insulin Resistance in People Exposed to Moderate-to-High Levels of Dioxin

Obesity, a risk factor for developing metabolic complications, is a major public health problem. Abdominal obesity is strongly accompanied by a cluster of metabolic abnormalities characterized by insulin resistance. The link between persistent organic pollutants (POPs) and insulin resistance has been investigated in animal and epidemiological studies. We aimed to examine whether insulin resistance is greater in people with abdominal obesity (AO) and concomitant exposure to serum dioxins (PCDD/Fs). We conducted a cross-sectional descriptive study of 2876 participants living near a PCDD/Fs contaminated area. Seventeen 2,3,7,8-substituted PCDD/Fs congeners were measured, and then the associations between the main predictor variable, serum TEQ_DF-1998, abdominal obesity (AO), dependent variables, and insulin resistance were examined. Twelve of the 17 congeners, widely distributed among PCDDs, and PCDFs, had trends for associations with abdominal adiposity. In men, the highest quintiles of 1,2,3,7,8-PeCDF; 1,2,3,7,8-PeCDD; 2,3,7,8-TCDD; 2,3,7,8-TCDF; and 2,3,4,7,8-PeCDF had the top five adjusted odds ratios (AORs) + 95% confidence intervals (CIs):[4.2; 2.7–6.4], [3.6; 2.3–5.7], [3.2; 2.1–5.0], [3.0; 2.0–4.5], and [2.9; 1.9–4.7], respectively. In women, the highest quintiles of 1,2,3,4,7,8,9-HpCDF; 1,2,3,6,7,8-HxCDF; and 1,2,3,4,6,7,8-HpCDF had the top three AORs + 95% CIs:[3.0; 1.9–4.7], [2.0; 1.3–3.1], and [1.9; 1.3–2.9], respectively. After confounding factors had been adjusted for, men, but not women, with higher serum TEQ_DF-1998 levels or abdominal obesity had a significantly (P_trend < 0.001) greater risk for abnormal insulin resistance. The groups with the highest joint serum TEQ_DF-1998 and abdominal obesity levels were associated with elevated insulin resistance at 5.0 times the odds of the groups with the lowest joint levels (AOR 5.23; 95% CI: 3.53–7.77). We hypothesize that serum TEQ_DF-1998 and abdominal obesity affect the association with insulin resistance in general populations.

Macronutrient composition determines accumulation of persistent organic pollutants from dietary exposure in adipose tissue of mice

Accumulation of persistent organic pollutants (POPs) has been linked to adipose tissue expansion. As different nutrients modulate adipose tissue development, we investigated the influence of dietary composition on POP accumulation, obesity development and related disorders. Lifespan was determined in mice fed fish-oil-based high fat diets during a long-term feeding trial and accumulation of POPs was measured after 3, 6 and 18months of feeding. Further, we performed dose-response experiments using four abundant POPs found in marine sources, PCB-153, PCB-138, PCB-118 and pp'-DDE as single congeners or as mixtures in combination with different diets: one low fat diet and two high fat diets with different protein:sucrose ratios. We measured accumulation of POPs in adipose tissue and liver and determined obesity development, glucose tolerance, insulin sensitivity and hepatic expression of genes involved in metabolism of xenobiotics. Compared with mice fed diets with a low protein:sucrose ratio, mice fed diets with a high protein:sucrose ratio had significantly lower total burden of POPs in adipose tissue, were protected from obesity development and exhibited enhanced hepatic expression of genes involved in metabolism and elimination of xenobiotics. Exposure to POPs, either as single compounds or mixtures, had no effect on obesity development, glucose tolerance or insulin sensitivity. In conclusion, this study demonstrates that the dietary composition of macronutrients profoundly modulates POP accumulation in adipose tissues adding an additional parameter to be included in future studies. Our results indicate that alterations in macronutrient composition might be an additional route for reducing total body burden of POPs.

Urinary polycyclic aromatic hydrocarbon metabolites levels in a representative sample of the Spanish adult population: The BIOAMBIENT.ES project

In 2009, the Spanish Ministry of Agriculture, Food and Environment promoted the BIOAMBIENT.ES project, a Human Biomonitoring program on the national scale to estimate reference levels of environmental pollutants on a representative sample of the Spanish adults. The present study focuses on polycyclic aromatic hydrocarbons (PAHs). The urinary metabolites 1-hydroxypyrene, 1-,2-,3-,4- and 9-hydroxyphenanthrene and 3-hydroxybenzo[a]pyrene were selected as indicators of PAH exposure. Urine samples from 957 subjects (16-65 years old) were collected during year 2009-2010. Geometric mean and 95th percentile for 1-hydroxypyrene in μg g(-1) creatinine were 0.117 (non-smoker: 0.079, smokers: 0.184) and 0.67 μg g(-1) creatinine (non-smokers: 0.31, smokers: 0.69) respectively. GM and 95th percentile for sum of hydroxyphenanthrenes in μg g(-1) creatinine were 0.130 (non-smokers: 0.089, smokers: 0.317) and 1.29 (non-smokers: 0.71, smokers: 1.51) respectively. 3-Hydroxybenzo[a]pyrene was below the limit of quantitation (0.05 μg L(-1)) in all cases. Significant differences (p<0.05) regarding smokers and non-smokers, coal and wood heating, body mass index and second hand smoke were found, while other variables like gender, age, or diet showed no significant association. The geographical distribution of the metabolites showed higher levels in people who lived in the north and northwest of Spain. The PAH metabolites levels found were in the same range or lower than those reported from other European countries and they were higher than those found in the U.S. This study represents the first nationwide survey of exposure to PAHs in Spain and provides a background reference range for exposure to PAHs in the Spanish adult occupied population.

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.

Early-life risk factors for chronic nonrespiratory diseases

We have witnessed a change in disease patterns contributing to the global burden of disease, with a shift from early childhood deaths due to the classic infectious communicable diseases to years lived with disability from chronic noncommunicable diseases. In both developing and developed countries, the years lived with disability attributable to chronic disease have increased: cardiovascular diseases by 17.7%; chronic respiratory disease by 8.5%; neurological conditions by 12.2%; diabetes by 30.0%; and mental and behavioural disorders by 5.0% over the past 20 years. Recognition of the contribution made by adverse environmental exposures in early life to noncommunicable diseases in later life is increasing. These early-life exposures appear to contribute to both chronic respiratory and chronic nonrespiratory diseases. In this State of the Art article, we aim to examine early-life environmental exposures that have an epidemiological association with chronic nonrespiratory diseases, such as obesity and type II diabetes, cardiovascular disease, and neurocognitive and behavioural problems. We will highlight the potential overlap in environmental risks with respiratory diseases, and point out knowledge gaps and research opportunities.

Determinants of bisphenol A and phthalate metabolites in urine of Flemish adolescents

As part of the second Flemish Environment and Health Study (FLEHS II), bisphenol-A (BPA) and different phthalate metabolites were analyzed, for the first time, in the urine of 210 adolescents in Flanders, Belgium. All chemicals had a detection frequency above 90%. For all compounds, except the sum of DEHP, highest levels were detected during spring. Average values for the Flemish adolescents were in an agreement with concentrations found in different international studies, all confirming the ubiquity of BPA and phthalate exposure. There was a significant correlation between BPA and the different phthalate metabolites (r between 0.26 and 0.39; p<0.01). Shared sources of exposure to BPA and phthalates, such as food packaging, were suggested to be responsible for this positive correlation. Different determinants of exposure were evaluated in relation to the urinary concentrations of these chemicals. For BPA, a significant association was observed with household income class, smoking and exposure to environmental tobacco smoke. For phthalates, the following significant associations were observed: age (MBzP), educational level of the adolescent (MBzP), equivalent household income (MnBP), use of personal care products (MnBP and MBzP), wall paper in house (MnBP and MBzP) and use of local vegetables (MnBP and MBzP).

Growth in Inuit children exposed to polychlorinated biphenyls and lead during fetal development and childhood

BACKGROUND

Because of their geographical location and traditional lifestyle, Canadian Inuit children are highly exposed to polychlorinated biphenyls (PCBs) and lead (Pb), environmental contaminants that are thought to affect fetal and child growth. We examined the associations of these exposures with the fetal and postnatal growth of Inuit children.

METHODS

We conducted a prospective cohort study among Inuit from Nunavik (Arctic Québec). Mothers were recruited at their first prenatal visit; children (n=290) were evaluated at birth and at 8-14 years of age. Concentrations of PCB 153 and Pb were determined in umbilical cord and child blood. Weight, height and head circumference were measured at birth and during childhood.

RESULTS

Cord blood PCB 153 concentrations were not associated with anthropometric measurements at birth or school age, but child blood PCB 153 concentrations were associated with reduced weight, height and head circumference during childhood. There was no association between cord Pb levels and anthropometric outcomes at birth, but cord blood Pb was related to smaller height and shows a tendency of a smaller head circumference during childhood.

INTERPRETATION

Our results suggest that chronic exposure to PCBs during childhood is negatively associated with skeletal growth and weight, while prenatal Pb exposure is related to reduced growth during childhood. This study is the first to link prenatal Pb exposure to poorer growth in school-age children.

Serum PCB levels in a representative sample of the Spanish adult population: the BIOAMBIENT.ES project

This manuscript presents the levels of six indicator polychlorinated biphenyl (PCB) congeners (IUPAC nos. 28, 52, 101, 138, 153 and 180) in the serum of 1880 individuals from a representative sample of the Spanish working population recruited between March 2009 and July 2010. Three out of the six PCBs studied (180, 153 and 138) were quantified in more than 99% of participants. PCB 180 was the highest contributor, followed by PCBs 153 and 138, with relative abundances of 42.6%, 33.2% and 24.2%, respectively. In contrast, PCBs 28 and 52 were detected in only 1% of samples, whereas PCB 101 was detectable in 6% of samples. The geometric mean (GM) for ΣPCBs138/153/180 was 135.4 ng/g lipid (95% CI: 121.3-151.2 ng/g lipid) and the 95th percentile was 482.2 ng/g lipid. Men had higher PCB blood concentrations than women (GMs 138.9 and 129.9 ng/g lipid respectively). As expected, serum PCB levels increased with age and frequency of fish consumption, particularly in those participants younger than 30 years of age. The highest levels we found were for participants from the Basque Country, whereas the lowest concentrations were found for those from the Canary Islands. The Spanish population studied herein had similar levels to those found previously in Greece and southern Italy, lower levels than those in France and central Europe, and higher PCB levels than those in the USA, Canada and New Zealand. This paper provides the first baseline information regarding PCB exposure in the Spanish adult population on a national scale. The results will allow us to establish reference levels, follow temporal trends and identify high-exposure groups, as well as monitor implementation of the Stockholm Convention in Spain.

Trace metals in blood and urine of newborn/mother pairs, adolescents and adults of the Flemish population (2007-2011)

The Flemish Centre for Environment and Health started with human biomonitoring in 2002 (FLEHS I: 2002-2006). The main goal of the second human biomonitoring cycle (FLEHS II: 2007-2011), was to determine mean values for a large number of pollutants in a representative sample of the general Flemish population. Values for Cd and Pb were updated, and a group of previously undetermined metals and metalloids (As, Mn, Cu and Tl) were included in some of the age groups. In this human biomonitoring program, three different age groups of the general Flemish population were monitored: 255 newborns and their mothers, 210 adolescents aged 14-15, and 204 adults between 20 and 40 years old. Trace elements were determined in cord blood and maternal blood of the mothers, in blood and urine of adolescents and in urine of adults. Determinants of life-style and personal factors were taken into account. The levels of trace elements in cord blood and maternal blood were for most elements at the lower end of the range found in literature. For Pb, As and Tl, a strong correlation (respectively r=0.43, 0.55 and 0.33; p<0.05) was found between levels in cord blood (respectively 8.6, 0.54 and 0.017 μg/L) and maternal blood (11.1, 0.64 and 0.028 μg/L), indicating that they are transported via the placenta from mother to fetus. The levels found in the adolescents and adults were compared with results from international biomonitoring studies, and were found to be in the same ranges. With the exception of Pb, all trace elements increased with increasing age group population. Finally, the results also showed that the levels of Cd and Pb in blood for this campaign (e.g. for Pb 8.6 and 14.8 μg/L in neonates and adolescents respectively) were lower compared to the first campaign (e.g. for Pb 14.7 and 21.7 μg/L in neonates and adolescents respectively), indicating a decrease over time. However, differences in sampling strategies might partially explain this observed trend.

Atherosclerotic process in taxi drivers occupationally exposed to air pollution and co-morbidities

Consistent evidence has indicated that the exposure to environmental air pollution increases the risk of cardiovascular disease. This study aimed to evaluate the possible effects of occupational exposure to air pollution, especially to polycyclic aromatic hydrocarbons (PAHs), and the influence of co-morbidities on the atherosclerotic process and inflammation. For that, biomarkers of exposure such as 1-hydroxypyrene urinary, oxidative damage and markers of cardiovascular risk were determined in plasma, serum and blood. In addition, inflammation models such as carotid intima-media thickness and serum inflammatory cytokines were analyzed in 58 taxi drivers with and without co-morbidity. The results demonstrated that considering only taxi drivers without co-morbidities, 15% presented carotid intima-media thickness above reference values. For the first time it has been demonstrated that urinary 1-hydroxypyrene levels were associated with carotid intima-media thickness and with serum homocysteine levels. The multiple linear regression analysis showed that several factors may contribute to the increased carotid intima-media thickness, among which age, interleukin-6, fibrinogen and exposure to PAHs stand out. In summary, our results suggest that chronic occupational exposure to atmospheric pollution could be an additional contributor to the atherogenesis process, leading to impaired vascular health. Moreover, carotid intima-media thickness, serum homocysteine levels, fibrinogen and the total cholesterol/HDL-c ratio could be suggested as preventive measures to monitor drivers' health.

Blood lead level association with lower body weight in NHANES 1999-2006

BACKGROUND

Lead exposure is associated with low birth-weight. The objective of this study is to determine whether lead exposure is associated with lower body weight in children, adolescents and adults.

METHODS

We analyzed data from NHANES 1999-2006 for participants aged ≥3 using multiple logistic and multivariate linear regression. Using age- and sex-standardized BMI Z-scores, overweight and obese children (ages 3-19) were classified by BMI ≥85 th and ≥95 th percentiles, respectively. The adult population (age ≥20) was classified as overweight and obese with BMI measures of 25-29.9 and ≥30, respectively. Blood lead level (BLL) was categorized by weighted quartiles.

RESULTS

Multivariate linear regressions revealed a lower BMI Z-score in children and adolescents when the highest lead quartile was compared to the lowest lead quartile (β (SE)=-0.33 (0.07), p<0.001), and a decreased BMI in adults (β (SE)=-2.58 (0.25), p<0.001). Multiple logistic analyses in children and adolescents found a negative association between BLL and the percentage of obese and overweight with BLL in the highest quartile compared to the lowest quartile (OR=0.42, 95% CI: 0.30-0.59; and OR=0.67, 95% CI: 0.52-0.88, respectively). Adults in the highest lead quartile were less likely to be obese (OR=0.42, 95% CI: 0.35-0.50) compared to those in the lowest lead quartile. Further analyses with blood lead as restricted cubic splines, confirmed the dose-relationship between blood lead and body weight outcomes.

CONCLUSIONS

BLLs are associated with lower body mass index and obesity in children, adolescents and adults.

Associations of urinary cadmium with age and urinary proteins: further evidence of physiological variations unrelated to metal accumulation and toxicity

BACKGROUND

The current risk assessment for environmental cadmium (Cd) largely relies on the assumption that urinary Cd (U-Cd) is a reliable biomarker of the Cd body burden. Recent studies have questioned the validity of this assumption.

OBJECTIVES

We studied the lifetime trend of U-Cd as a function of diuresis, gender, smoking status, and protein tubular reabsorption. We also analyzed the associations between U-Cd and urinary proteins.

METHODS

Cd, retinol-binding protein, and albumin were measured in the urine of six cohorts of the general population of Belgium, with a mean age ranging from 5.7 to 88.1 years (n = 1,567). Variations of U-Cd with age were modeled using natural cubic splines.

RESULTS

In both genders, U-Cd decreased to a minimum (~ 0.20 μg/L) at the end of adolescence, then increased until 60-70 years of age (~ 0.60 μg/L in never-smokers) before leveling off or decreasing. When U-Cd was expressed in micrograms per gram of creatinine, these variations were amplified (minimum, 0.15 µg/g creatinine; maximum, 0.70 µg/g creatinine) and much higher U-Cd values were observed in women. We observed no difference in U-Cd levels between never-smokers and former smokers, and the difference with current smokers did not increase over time. Lifetime curves of U-Cd were higher with increasing urinary retinol-binding protein or albumin, a consequence of the coexcretion of Cd with proteins.

CONCLUSIONS

At low Cd exposure levels, U-Cd and age are associated through nonlinear and nonmonotonic relationships that appear to be driven mainly by recent Cd intake and physiological variations in the excretion of creatinine and proteins.

Environmental exposure to metals and children's growth to age 5 years: a prospective cohort study

In this prospective cohort study, based on 1,505 mother-infant pairs in rural Bangladesh, we evaluated the associations between early-life exposure to arsenic, cadmium, and lead, assessed via concentrations in maternal and child urine, and children's weights and heights up to age 5 years, during the period 2001–2009. Concurrent and prenatal exposures were evaluated using linear regression analysis, while longitudinal exposure was assessed using mixed-effects linear regression. An inverse association was found between children's weight and height, age-adjusted z scores, and growth velocity at age 5 years and concurrent exposure to cadmium and arsenic. In the longitudinal analysis, multivariable-adjusted attributable differences in children's weight at age 5 years were −0.33 kg (95% confidence interval (CI): −0.60, −0.06) for high (≥95th percentile) arsenic exposure and −0.57 kg (95% CI: −0.88, −0.26) for high cadmium exposure, in comparison with children with the lowest exposure (≤5th percentile). Multivariable-adjusted attributable differences in height were −0.50 cm (95% CI: −1.20, 0.21) for high arsenic exposure and −1.6 cm (95% CI: −2.4, −0.77) for high cadmium exposure. The associations were apparent primarily among girls. The negative effects on children's growth at age 5 years attributable to arsenic and cadmium were of similar magnitude to the difference between girls and boys in terms of weight (−0.67 kg, 95% CI: −0.82, −0.53) and height (−1.3 cm, 95% CI: −1.7, −0.89).