Associations of Maternal Serum Perfluoroalkyl Substances Concentrations with Early Adolescent Bone Mineral Content and Density: The Health Outcomes and Measures of the Environment (HOME) Study

Per- and polyfluoroalkyl substances and bone mineral content in early adolescence: Modification by diet and physical activity

BACKGROUND

Per- and polyfluoroalkyl substance (PFAS) exposures may negatively impact bone mineral accrual, but little is known about potential mitigators of this relation. We assessed whether associations of PFAS and their mixture with bone mineral content (BMC) in adolescence were modified by diet and physical activity.

METHODS

We included 197 adolescents enrolled in a prospective pregnancy and birth cohort in Cincinnati, Ohio (2003-2006). At age 12 years, we collected serum for PFAS measurements and used dual-energy x-ray absorptiometry to measure BMC. We calculated dietary calcium intake and Health Eating Index (HEI) scores from repeated 24-h dietary recalls, physical activity scores using the Physical Activity Questionnaire for Older Children (PAQ-C), and average moderate to vigorous physical activity (MVPA) based on accelerometry. We estimated covariate-adjusted differences in BMC z-scores per interquartile range (IQR) increase of individual PFAS concentrations using linear regression and per simultaneous IQR increase in all four PFAS using g-computation. We evaluated effect measure modification (EMM) using interaction terms between each modifier and PFAS.

RESULTS

Higher serum perfluorooctanoic acid, perfluorooctanesulfonic acid, and perfluorononanoic acid concentrations and the PFAS mixture were associated with lower BMC z-scores. An IQR increase in all PFAS was associated with a 0.27 (-0.54, 0.01) lower distal radius BMC z-score. Associations with lower BMC were generally stronger among adolescents classified as < median for calcium intake, HEI scores, or MVPA compared to those ≥ median. The difference in distal radius BMC z-score per IQR increase in all PFAS was -0.38 (-0.72, -0.04) for those with

CONCLUSION

Healthy, calcium-rich diets and higher intensity physical activity may mitigate the adverse impact of PFAS on adolescent bone health.

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Key Words

• Adolescent health
• Bone mineral content
• Calcium
• Diet
• Perfluoroalkyl substances
• Physical activity

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MESH Headings

• Humans
• Female
• Fluorocarbons/blood
• Male
• Bone Density/drug effects
• Child
• Adolescent
• Diet
• Environmental Pollutants/blood
• Prospective Studies
• Ohio
• Alkanesulfonic Acids/blood
• Exercise
• Motor Activity/drug effects

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Grants

• R01 ES030078 NIEHS NIH HHS
• R01 ES033252 NIEHS NIH HHS
• R01 ES027224 NIEHS NIH HHS
• L40 ES032257 NIEHS NIH HHS
• P01 ES011261 NIEHS NIH HHS
• R01 ES032836 NIEHS NIH HHS
• R01 ES028277 NIEHS NIH HHS
• T32 ES007141 NIEHS NIH HHS
• R01 ES025214 NIEHS NIH HHS
• R01 ES020349 NIEHS NIH HHS

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Affiliation(s)

Jessie P Buckley Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
Junyi Zhou Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, USA
Katherine M Marquess Department of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, USA
Bruce P Lanphear Faculty of Health Sciences, Simon Fraser University, Vancouver, Canada
Kim M Cecil Department of Radiology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, USA; Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, USA
Aimin Chen Department of Biostatistics, Epidemiology and Informatics, University of Pennsylvania Perelman School of Medicine, Philadelphia, USA
Clara G Sears Christina Lee Brown Envirome Institute, Department of Medicine, Division of Environmental Medicine, University of Louisville, KY, USA
Yingying Xu Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, USA
Kimberly Yolton Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, USA
Heidi J Kalkwarf Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, USA
Joseph M Braun Department of Epidemiology, Brown University, Providence, USA
Jordan R Kuiper Department of Environmental and Occupational Health, The George Washington University Milken Institute School of Public Health, Washington, D.C., USA

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Exposure to per- and polyfluoroalkyl substances and bone health: a systematic review and meta-analysis

Perfluoroalkyl substances (PFAS) as a large group of synthetic compounds widely contaminated the environment and lead to health problems. However, the correlation between PFAS exposure, bone health parameters and osteoporosis remains controversial. Therefore, we conducted a systematic review and meta-analysis of published literature to evaluate the effects of PFAS on human bone health. All observational studies were collected up to 2 December 2023. A total of 2096 articles were retrieved. Of these, 21 articles investigated the association between PFAS exposure and human bone health. However, only 10 studies were included in the final meta-analysis. Doubling of serum perfluorooctanoic acid (PFOA) (β = -0.11, 95% confidence interval (CI): -0.18, -0.05) and perfluorooctane sulfonic acid (PFOS) (β = -0.06, 95% CI: -0.11, -0.01) levels showed significant negative correlations with total body less head bone mineral density (TBLH-BMD). Subgrouping showed that only perfluorohexane sulfonate (PFHxS) (odds ratio [OR] = 1.37, 95% CI: 1.12, 1.68) was correlated with osteoporosis.

A realistic mixture of ubiquitous persistent organic pollutants affects bone and cartilage development in zebrafish by interaction with nuclear receptor signaling

"Persistent organic pollutants (POPs)" have a plethora of deleterious effects on humans and the environment due to their bioaccumulative, persistent, and mimicking properties. Individually, each of these chemicals has been tested and its effects measured, however they are rather found as parts of complex mixtures of which we do not fully grasp the extent of their potential consequences. Here we studied the effects of realistic, environmentally relevant mixtures of 29 POPs on cartilage and bone development using zebrafish as a model species. We observed developmental issues in cartilage, in the form of diverse malformations such as micrognathia, reduced size of the Meckel's and other structures. Also, mineralized bone formation was disrupted, hence impacting the overall development of the larvae at later life stages. Assessment of the transcriptome revealed disruption of nuclear receptor pathways, such as androgen, vitamin D, and retinoic acid, that may explain the mechanisms of action of the compounds within the tested mixtures. In addition, clustering of the compounds using their chemical signatures revealed structural similarities with the model chemicals vitamin D and retinoic acid that can explain the effects and/or enhancing the phenotypes we witnessed. Further mechanistic studies will be required to fully understand this kind of molecular interactions and their repercussions in organisms. Our results contribute to the already existing catalogue of deleterious effects caused by exposure to POPs and help to understand the potential consequences in at risk populations.

Exposure to perfluoroalkyl substances and longitudinal changes in bone mineral density in adolescents and young adults: A multi-cohort study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) may impair bone development in adolescence, which impacts life-long bone health. No previous studies have examined prospective associations of individual PFAS and their mixture with bone mineral density (BMD) changes in Hispanic young persons, a population at high risk of osteoporosis in adulthood.

OBJECTIVES

To examine associations of individual PFAS and PFAS mixtures with longitudinal changes in BMD in an adolescent Hispanic cohort and examine generalizability of findings in a mixed-ethnicity young adult cohort (58.4% Hispanic).

METHODS

Overweight/obese adolescents from the Study of Latino Adolescents at Risk of Type 2 Diabetes (SOLAR; n = 304; mean follow-up = 1.4 years) and young adults from the Southern California Children's Health Study (CHS; n = 137; mean follow-up = 4.1 years) were included in this study. Plasma PFAS were measured at baseline and dual x-ray absorptiometry scans were performed at baseline and follow-up to measure BMD. We estimated longitudinal associations between BMD and five PFAS via separate covariate-adjusted linear mixed effects models, and between BMD and the PFAS mixture via quantile g-computation.

RESULTS

In SOLAR adolescents, baseline plasma perfluorooctanesulfonic acid (PFOS) was associated with longitudinal changes in BMD. Each doubling of PFOS was associated with an average -0.003 g/cm2 difference in change in trunk BMD per year over follow-up (95% CI: -0.005, -0.0002). Associations with PFOS persisted in CHS young adults, where each doubling of plasma PFOS was associated with an average -0.032 g/cm2 difference in total BMD at baseline (95% CI -0.062, -0.003), though longitudinal associations were non-significant. We did not find associations of other PFAS with BMD; associations of the PFAS mixture with BMD outcomes were primarily negative though non-significant.

DISCUSSION

PFOS exposure was associated with lower BMD in adolescence and young adulthood, important periods for bone development, which may have implications on future bone health and risk of osteoporosis in adulthood.

Prenatal and early postnatal exposure to perfluoroalkyl substances and bone mineral content and density in the Odense Child Cohort

INTRODUCTION

Exposure to perfluoroalkyl substances (PFAS) has been associated with lower bone mineral density (BMD) in animal and human studies, but prospective data from children are limited.

OBJECTIVES

To determine associations between prenatal and early postnatal PFAS exposure and BMD at age 7 years.

METHODS

In the Odense Child Cohort, Denmark, pregnant women were recruited in 2010-2012, and their children were invited for subsequent health examinations. At 12 weeks of gestation the pregnant women delivered a serum sample, and at age 18 months serum was obtained from the child to measure perfluorooctane sulfonic acid(PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) by LC-MS/MS. At age 7 years DXA scans were performed to measure bone mineral content (BMC) and BMD Z-score. PFAS in pregnancy (n = 881) and/or at age 18 months (n = 668) were regressed against DXA measurements, adjusted for maternal education, child height Z-score, sex (for BMC) and for postnatal exposure, additionally duration of total breastfeeding. We additionally performed structural equation models determining combined effects of pre-and postnatal PFAS exposures.

RESULTS

Higher prenatal and early postnatal serum concentrations of all measured PFAS were associated with lower BMC and BMD Z-scores at age 7 years, all estimates were negative although not all significant. For each doubling of 18-month exposure to PFNA or PFOS, BMD Z-scores were lowered by -0.10 (95 % CI -0.19;-0.00) and -0.08 (-0.17;-0.00), respectively after adjustment. Pre- and postnatal PFAS were correlated, but structural equation models suggested that associations with BMD were stronger for 18-month than prenatal PFAS exposure.

DISCUSSION

Bone density is established in childhood, and a reduction in BMD during early childhood may have long-term implication for peak bone mass and lifelong bone health. Future studies of the impact of PFAS exposure on fracture incidence will help elucidate the clinical relevance.

Effects of urinary barium exposure on bone mineral density in general population

Previous studies have reported that exposures to metals are associated with bone health, but are mostly restricted to a few of the most frequent hazardous metals. The effects of barium (Ba) are not fully understood. A cross-sectional study involving 1532 adults from the National Health and Nutrition Examination Survey (NHANES, 2013-2016) was conducted. Generalized linear model (GLM) and restricted cubic spline (RCS) were applied to evaluate the relationship of urinary Ba exposure with BMDs. According to the GLM analyses, urinary Ba was adversely correlated with total BMD (percent change: -0.75; 95% CI: -1.21, -0.29) and lumbar BMD (percent change: -0.76; 95% CI: -1.47, -0.04). Compared with the lowest tertile of Ba levels, the percentage change of T3 was -2.06 (-3.36, -0.73) for total BMD and was -2.39 (-4.51, -0.24) for lumbar BMD, showing a significant linear trend (P trend = 0.014 and P trend = 0.047, respectively). The RCS models showed a monotonically decreasing relationship of urinary Ba with total BMD and lumbar BMD. Moreover, the positive joint effects were observed between Pb (lead) and Ba, and Cd (cadmium) and Ba on BMDs. According to our findings, exposure to Ba may lead to a decrease in BMDs. Possible positive joint effects of Ba and Pb, and Ba and Cd on BMDs were found. Exposure to Ba may contribute to poor skeletal health.

Associations of prenatal and postnatal exposure to perfluoroalkyl substances with pubertal development and reproductive hormones in females and males: The HOME study

BACKGROUND

Prenatal and childhood exposure to per- and polyfluoroalkyl substances (PFAS) may be associated with lower reproductive hormones and later puberty, but epidemiological studies evaluating these associations are scarce.

OBJECTIVES

We examined associations of PFAS concentrations assessed from pregnancy to adolescence with pubertal development and reproductive hormones at age 12 years.

METHODS

We studied 200 mother-child pairs from the HOME Study in Cincinnati, OH (enrolled: 2003-2006). We quantified serum concentrations of perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoate (PFNA), and perfluorohexane sulfonate (PFHxS) in pregnant women and their children at age 3, 8 and 12 years. At age 12 years, children self-assessed pubertal development using Tanner staging of pubic hair growth (males and females) and breast growth (females), and age at menarche. We quantified serum concentrations of dehydroepiandrosterone sulfate, luteinizing hormone, and follicle-stimulating hormone in both sexes; estradiol in females; testosterone in males. We estimated associations of PFAS with pubertal outcomes and reproductive hormones using a combination of ordinal regression, Cox proportional-hazard regression, and linear regression. Quantile-based g-computation was used for PFAS mixture.

RESULTS

In females, adolescent PFAS concentrations and their mixture were associated with later pubic hair growth, breast maturation, and age at menarche, but there was no pattern for prenatal or other postnatal concentrations. For instance, in females, each doubling in adolescent PFAS concentrations was associated with 79 % (PFOA), 63 % (PFOS), 56 % (PFNA), and 47 % (PFHxS) lower odds of attaining a higher stage for breast growth. In addition, adolescent PFAS concentrations were consistently associated with lower estradiol concentrations in females. No pattern was observed for associations of PFAS concentrations with pubic hair growth or reproductive hormones in males.

CONCLUSIONS

We observed associations between PFAS concentrations in adolescence and later pubertal development in females, but this could be due to reverse causation induced by excretion of PFAS through menstrual fluid.

A New Interpretation of Relative Importance on an Analysis of Per and Polyfluorinated Alkyl Substances (PFAS) Exposures on Bone Mineral Density

BACKGROUND

The relative contribution of environmental contaminants is an important, and frequently unanswered, question in human or ecological risk assessments. This interpretation of relative importance allows determination of the overall effect of a set of variables relative to other variables on an adverse health outcome. There are no underlying assumptions of independence of variables. The tool developed and used here is specifically designed for studying the effects of mixtures of chemicals on a particular function of the human body.

METHODS

We apply the approach to estimate the contributions of total exposure to six PFAS (perfluorodecanoic acid, perfluorohexane sulfonic acid, 2-(N-methyl-PFOSA) acetate, perfluorononanoic acid, perfluoroundecanoic acid and perfluoroundecanoic acid) to loss of bone mineral density relative to other factors related to risk of osteoporosis and bone fracture, using data from subjects who participated in the US National Health Examination and Nutrition Surveys (NHANES) of 2013-2014.

RESULTS

PFAS exposures contribute to bone mineral density changes relative to the following variables: age, weight, height, vitamin D2 and D3, gender, race, sex hormone binding globulin, testosterone, and estradiol.

CONCLUSION

We note significant alterations to bone mineral density among more highly exposed adults and significant differences in effects between men and women.

Contact to perfluoroalkyl substances and thyroid health effects: A meta-analysis directing on pregnancy

In vivo, in vitro, and epidemiological evidence suggests that perfluoroalkyl substances (PFAS) may alter thyroid function in human health, with negative effects on maternal and fetal development outcomes. However, data on the effects of PFAS on thyroid hormones remain controversial. Here, we conducted a meta-analysis of 13 eligible studies searched from Embase, PubMed, and Web of Science by July 10, 2022, to explore the relationship between maternal exposure to PFAS and thyroid health effects, including thyroid stimulating hormone (TSH), triiodothyronine (TT3), thyroxin (TT4), free T3 (FT3), and free T4 (FT4). The estimated values (β) and the corresponding confidence intervals (95%CI) were extracted for analysis. The tests for heterogeneity, sensitivity and publication bias between studies were performed using Stata 15.0. The combined results showed a positive association between changes in TSH and exposure to perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorodecanoic acid (PFDA), with no significant correlation observed between changes in other thyroid hormones and exposure to PFAS. This difference was attributed to sample size, region, sample type, body mass index (BMI), and gestational week. Our data recommend verifying the relationship between PFAS exposure and thyroid health effects in a large sample population cohort in future studies. In addition, health care should be taken into account in early and mid-pregnancy.

High exposure to perfluoroalkyl substances in drinking water is associated with increased risk of osteoporotic fractures - A cohort study from Ronneby, Sweden

BACKGROUND

Perfluoroalkyl substances (PFAS) have been reported to be related to decreased bone mineral density, but the relationship with osteoporosis and fractures is less studied. This study aimed to investigate the risks of osteoporotic fractures in a Swedish population with long-term exposure to PFAS through drinking water.

METHODS

The Ronneby Register Cohort, including 61,504 individuals who had ever lived in Ronneby during 1985-2013, was used. Exposure to PFAS was assessed according to the yearly residential address with or without highly contaminated water supply and was categorized as 'never-high' and 'ever-high' exposure. The 'ever-high' exposure was further divided into 'early-high' and 'late-high' depending on if the exposure was before or after 2005. Inpatient and outpatient hospital diagnoses of fractures were retrieved from the National Patient Register. Major osteoporotic fractures (MOF, i.e., hip, vertebrae, proximal humerus and distal forearm fractures), and hip fractures were considered as the primary outcomes. Cox proportional hazard models with time-varying exposure were used to estimate the hazard ratios (HRs). Stratified analyses were performed in each sex and age group (<50 yrs and ≥ 50 yrs).

RESULTS

Elevated risks of MOF (HR 1.11, 95% CI 1.03-1.19) and hip fractures (1.12, 1.00-1.24) were observed when comparing 'ever-high' to 'never-high' exposure. The HRs were even higher for 'late-high' exposure (MOF: 1.29, 1.16-1.44; hip fractures: 1.22, 1.01-1.47). Further adjustment for highest achieved education slightly attenuated the estimates. Individuals above 50 years old showed even higher HR estimates. Similar patterns were found for all fractures.

CONCLUSION

Our results provide further evidence supporting the adverse effects of PFAS on osteoporosis. A better understanding of dose-response relationships as a basis for risk assessment is warranted.

The vitamin D receptor as a potential target for the toxic effects of per- and polyfluoroalkyl substances (PFASs): An in-silico study

Due to their persistence and toxicity, perfluoroalkyl and polyfluoroalkyl substances (PFASs) constitute significant hazards to human health and the environment. Their effects include immune suppression, altered hormone levels, and osteoporosis. Recently, the most studied PFAS, perfluorooctanoic acid (PFOA), was shown to competitively binding to the Vitamin D receptor (VDR). VDR plays a crucial role in regulating genes involved in maintaining immune, endocrine, and calcium homeostasis, suggesting it may be a target for at least some of the health effects of PFAS. Hence, this study examined the potential binding of 5206 PFASs to VDR using molecular docking, molecular dynamics, and free energy binding calculations. We identified 14 PFAS that are predicted to interact strongly with VDR, similar to the natural ligands. We further investigated the interactions of VDR with 256 PFASs of established commercial importance. Eighty-three (32%) of these 256 commercially important PFAS were predicted to be stronger binders to VDR than PFOA. At least 16 PFASs of regulatory importance, because they have been identified in water supplies and human blood samples, were also more potent binders to VDR than PFOA. Further, PFASs are usually found together in contaminated drinking water and human blood samples, which raises the concern that multiple PFASs may act together as a mixture on VDR function, potentially producing harmful effects on the immune, endocrine, and bone homeostasis.

Early life organophosphate ester exposures and bone health at age 12 years: The Health Outcomes and Measures of the Environment (HOME) Study

BACKGROUND

No human studies have evaluated early life organophosphate ester (OPE) exposures with bone health outcomes, despite evidence of osteotoxicity.

OBJECTIVES

We assessed associations of urinary OPE metabolites measured across early life with areal bone mineral density (aBMD) and bone mineral content (BMC) at age 12 years.

METHODS

Among 223 mother-child dyads enrolled in the Health Outcomes and Measures of the Environment (HOME) Study, we quantified concentrations of bis-2-chloroethyl phosphate (BCEP), bis-(1,3-dichloro-2-propyl) (BDCIPP), di-n-butyl phosphate (DnBP), and diphenyl phosphate (DPHP) in urine collected from mothers during pregnancy and children at ages 1, 2, 3, 5, and 8 years. At age 12 years, we performed dual energy x-ray absorptiometry and calculated aBMD and BMC z-scores at six skeletal sites. We estimated overall and sex-stratified BMD/BMC z-score differences per interquartile range (IQR) increase in OPE concentrations at multiple exposure timepoints: gestation (average) and 1-3 (average), 5, and 8 years.

RESULTS

In adjusted models, overall associations of BCEP and BDCIPP with total hip and 1/3rd distal radius aBMD and BMC varied significantly by exposure timepoint, as did BDCIPP with whole body aBMD. For example, differences (95 % CI) in total hip aBMD z-score per IQR increase in BDCIPP were 0.33 (0.01, 0.64), -0.10 (-0.34, 0.14), -0.18 (-0.40, 0.05), and 0.14 (-0.09, 0.38) for concentrations during gestation and at 1-3, 5, and 8 years, respectively. Overall DnBP and DPHP associations were generally null at all timepoints. We observed sex-specific associations for some timepoints and skeletal sites. For example, an IQR increase in 8-year DPHP was associated with a 0.21 (0.05, 0.38) greater total hip aBMD z-score among females but -0.19 (-0.43, 0.05) lower z-score among males.

DISCUSSION

Early life OPE exposures may be associated with sex- and exposure period-dependent alterations in early adolescent bone mineral accrual and strength.

Bone mass density following developmental exposures to perfluoroalkyl substances (PFAS): a longitudinal cohort study

BACKGROUND

Environmental exposures to industrial chemicals, including perfluoroalkyl substances (PFAS), may play a role in bone development and future risk of osteoporosis. However, as prospective evidence is limited, the role of developmental PFAS exposures in bone density changes in childhood is unclear. The objective of this study was to estimate associations between serum-PFAS concentrations measured in infancy and early childhood and areal bone mineral density (aBMD) measured at age 9 years in a birth cohort of children from the Faroe Islands.

METHODS

We prospectively measured concentrations of five PFAS in cord serum and serum collected at 18 months, 5 years and 9 years, and conducted whole-body DXA scans at the 9-year clinical visit. Our study included 366 mother-child pairs with DXA scans and at least one PFAS measurement. We estimated covariate-adjusted associations of individual PFAS concentrations with age-, sex- and height-adjusted aBMD z-scores using multivariable regression models and applied formal mediation analysis to estimate the possible impact of by several measures of body composition. We also evaluated whether associations were modified by child sex.

RESULTS

We found PFAS exposures in childhood to be negatively associated with aBMD z-scores, with the strongest association seen for perfluorononanoic acid (PFNA) at age 5 years. A doubling in age-5 PFNA was associated with a 0.15 decrease in aBMD z-score (95% CI: - 0.26, - 0.039). The PFNA-aBMD association was significantly stronger in males than females, although effect modification by sex was not significant for other PFAS exposures. Results from the mediation analysis suggested that any potential associations between aBMD and 18-month PFAS concentrations may be mediated by total body fat and BMI, although most estimated total effects for PFAS exposures at age 18 months were non-significant. PFAS exposures at age 9 were not associated with age-9 aBMD z-scores.

CONCLUSIONS

The PFAS-aBMD associations identified in this and previous studies suggest that bone may be a target tissue for PFAS. Pediatric bone density has been demonstrated to strongly track through young adulthood and possibly beyond; therefore, these prospective results may have important public health implications.

Prenatal and early postnatal exposure to perfluoroalkyl substances and bone mineral content and density in the Odense child cohort

INTRODUCTION

Exposure to perfluoroalkyl substances (PFAS) has been associated with lower bone mineral density (BMD) in animal and human studies, but prospective data from children are limited.

OBJECTIVES

To determine associations between prenatal and early postnatal PFAS exposure and BMD at age 7 years.

METHODS

In the Odense Child Cohort, Denmark, pregnant women were recruited in 2010-2012, and their children were invited for subsequent health examinations. At 12 weeks of gestation the pregnant women delivered a serum sample, and at age 18 months serum was obtained from the child to measure perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) by LC-MS/MS. At age 7 years DXA scans were performed to measure bone mineral content (BMC) and BMD Z-score. PFAS in pregnancy (n = 924) and/or at age 18 months (n = 511) were regressed against DXA measurements, adjusted for maternal education, child height Z-score, sex (for BMC) and for postnatal exposure, additionally duration of total breastfeeding. We additionally performed structural equation models determining combined effects of pre-and postnatal PFAS exposures.

RESULTS

Higher prenatal and early postnatal serum concentrations of all measured PFAS were associated with lower BMC and BMD Z-scores at age 7 years, all estimates were negative although not all significant. For each doubling of prenatal or 18-month exposure to PFDA, BMD Z-scores were lowered by -0.07 (95 % CI -0.10; -0.03) and -0.14 (-0.25; -0.03), respectively after adjustment. Pre- and postnatal PFAS were correlated, but structural equation models suggested that associations with BMD were stronger for 18-month than prenatal PFAS exposure.

DISCUSSION

Bone density is established in childhood, and a reduction in BMD during early childhood may have long-term implication for peak bone mass and lifelong bone health. Future studies of the impact of PFAS exposure on fracture incidence will help elucidate the clinical relevance.

Serum PFAS and Urinary Phthalate Biomarker Concentrations and Bone Mineral Density in 12-19 Year Olds: 2011-2016 NHANES

CONTEXT

Per- and polyfluoroalkyl substances (PFAS) and phthalates are 2 families of environmental endocrine disruptors that may be associated with areal lower bone mineral density (aBMD).

OBJECTIVE

To examine associations between serum PFAS and urinary phthalate biomarker concentrations and their mixtures with aBMD Z-scores in adolescents.

DESIGN, PATIENTS, AND MEASURES

We examined serial cross-sectional data from male (n = 453) and female (n = 395) 12- to 19-year-old participants in the 2011 through 2016 National Health and Nutrition Examination Survey with measures of serum PFAS, urinary phthalate metabolites, and dual-energy X-ray absorptiometry aBMD Z-scores (total body less head). In sex-specific models, we used linear regression to examine associations of individual PFAS and phthalate biomarkers with aBMD Z-scores, and Bayesian kernel machine regression to examine the association of the overall PFAS/phthalate biomarker mixture with aBMD Z-scores. We replicated the analysis, stratifying by race/ethnicity.

RESULTS

Participants were (mean ± SD) 15 ± 2.1 years of age. In males, each doubling of serum perfluorooctanoate (PFOA), perfluorooctane sulfonate, urinary mono-isobutyl phthalate (MiBP), mono-n-butyl phthalate, and the overall PFAS/phthalate mixture was associated with a lower aBMD Z-score (eg, for PFOA: -0.24; 95% CI, -0.41 to -0.06). Serum PFOA and urinary MiBP were associated with higher aBMD Z-scores in females (eg, for PFOA: 0.09; 95% CI, -0.07 to 0.25). Findings did not differ by race/ethnicity.

CONCLUSIONS

Certain PFAS and phthalates may be associated with reduced bone mineral density in adolescent males. Bone mineral density tracks across the life course, so if replicated in longitudinal cohorts, this finding may have implications for lifelong skeletal health.

Association between perfluoroalkyl substances concentration and bone mineral density in the US adolescents aged 12-19 years in NHANES 2005-2010

BACKGROUND

Reports on the association of perfluoroalkyl substances (PFASs) exposure with adolescent bone health are scarce, and studies have primarily targeted maternal serum.

OBJECTIVE

We evaluated the relationship between autologous serum perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS) and perfluorononanoic acid (PFNA) levels and bone mineral density (BMD) in adolescents.

METHODS

We analyzed data from 1228 adolescents aged 12-19 years in the National Health and Nutrition Examination Survey (NHANES) 2005-2010 and used multiple regression analysis to identify the relationship between serum PFOA, PFOS, PFHxS, and PFNA concentrations and total femur, femoral neck, and lumbar spine BMD, in addition to multiple stratified subgroup analyses.

RESULTS

The mean age of participants was 15 years, males had higher serum PFAS concentrations than females. The results of multiple regression analysis showed that the natural log(ln)-transformed serum PFOA, PFOS, and PFNA concentrations were negatively correlated with total femur, femoral neck, and lumbar spine BMD (all p < 0.05), and ln-PFHxS was positively correlated with total femur and femoral neck BMD (all p< 0.05). In males, ln-PFOA was negatively associated with total femur and lumbar spine BMD (all p< 0.05), ln-PFOS was associated with the reduced total femur, femoral neck, and lumbar spine BMD (all p< 0.05), while ln-PFHxS and ln-PFNA were not observed to correlate with BMD at these three sites. In females, both ln-PFOA and ln-PFOS were negatively correlated with total femur and lumbar spine BMD (all p< 0.05), ln-PFHxS is associated with the increased total femur and femoral neck BMD (all p< 0.05), and ln-PFNA was negatively correlated with total femur and femoral neck BMD (all p< 0.05), most of the associations were confined to females. The associations of ln-PFOS with femoral neck BMD and ln-PFNA with total femur BMD were more significant in those who were overweight/obese and had anemia, respectively (all p for interaction < 0.05).

CONCLUSIONS

In this representative sample of US adolescents aged 12-19 years, certain PFAS were associated with lower bone mineral density, and most of the associations were confined to females. The negative effect of PFAS on BMD is more pronounced in those who are overweight/obese and have anemia. However, further studies are needed to confirm this finding.