Bone mineral density and blood metals in premenopausal women

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.

Association of blood mercury levels with bone mineral density in adolescents aged 12-19

Bone mass increases rapidly in adolescence, and achieving higher bone mineral density (BMD) during this period can help prevent osteoporosis. However, the effects of metallic mercury on bone health remain controversial. Previous studies have discussed perimenopausal women and older adults, while the association of blood mercury with BMD in adolescents is yet to be studied. Date was collected from the National Health and Nutrition Examination Survey (NHANES) 2011-2018. Weighted multiple linear regression models were used to explore the association of blood mercury levels with BMD in adolescents, while smooth curve fittings and weighted generalized additive models were used to identify the potential nonlinear association. We found that blood mercury levels were negatively associated with BMD in adolescents, though not significantly, based on the results of statistical analyses of 2818 participants. Additionally, the trend in BMD with changes in blood mercury was different in male and female adolescents. We also found an inverted U-shaped association between blood mercury and BMD in male and Mexican-American adolescents. This suggests that increased blood mercury levels within a range may benefit bone health in male adolescents (inflection point: 5.44 nmol/L) and Mexican-American adolescents (inflection point: 5.49 nmol/L), while higher blood mercury levels may harm bone health. More prospective research is needed to confirm our findings.

Normal concentration range of blood mercury and bone mineral density: a cross-sectional study of National Health and Nutrition Examination Survey (NHANES) 2005-2010

High blood mercury levels could lead to mercury poisoning, undoubtedly causing great harm to human health. However, the impact of the normal concentration of blood mercury on bone mineral density (BMD) is unclear. Therefore, this study explored the relationship between blood mercury levels and BMD and determined whether the relationship between blood mercury and BMD differs by populations. Two researchers extracted data from the 2005-2010 National Health and Nutrition Examination Survey database. Multivariate linear regression models were performed to evaluate the relationship between mercury level and BMD of the femoral regions and spine. Subgroup analysis was used to estimate differences according to population subgroups. Moreover, the nonlinear relationship of blood mercury levels and BMD was assessed using smooth curve fitting and generalized additive models. The results showed increased BMD with increasing mercury levels by multivariable-adjusted linear regression models, especially in the femoral regions. Subgroup analysis showed that the relationship was more likely to be present in non-Hispanic Whites, while a negative correlation between blood mercury levels and spinal BMD was observed in non-Hispanic Blacks. Furthermore, males (aged 20 to 29 years) and females (aged 30 to 39 years) with low blood mercury levels (< 3 ug/L) had increased risks of osteopenia or osteoporosis. This study showed that blood mercury level within the normal reference value of 10 μg/dL may be associated with BMD, especially with a lower blood mercury level, which may suggest an elevated risk of osteopenia or osteoporosis. However, causation could not be established due to the study design.

Urine Cadmium as a Risk Factor for Osteoporosis and Osteopenia: A Meta-Analysis

Background: As society ages, the incidence of osteoporosis increases. In several studies, cadmium (Cd) is thought to be related to osteoporosis. However, there are conflicting reports about the relationship between Cd and the risk of osteoporosis and osteopenia. Therefore, the purpose of this meta-analysis was to explore the relationship between Cd and osteoporosis and osteopenia.

Methods: Through a review of the literature, articles published in PubMed as of December 2020 were identified and the references of related publications and reviews were reviewed. Ultimately, 17 eligible articles were selected to determine the relationship between blood and urine Cd concentrations for the risk of osteoporosis or osteopenia. In this study, we performed a classification analysis, heterogeneity test, subgroup analysis, and evaluated publication bias.

Results: A total of 17 studies were included, including seven on blood Cd and 10 on urine Cd. By combining the odds ratio (OR) and 95% confidence interval (CI) for the lowest and highest categories, the odds ratio of blood Cd concentration that increased the risk of osteoporosis or osteopenia was OR 1.21 (95% CI: 0.84–1.58) and that of urine Cd concentration that increased the risk of osteoporosis or osteopenia was OR 1.80 (95% CI: 1.42–2.18), and the results of the subgroup analysis were also consistent.

Conclusions: Our research indicates that while urine cadmium (Cd) concentration may be related to increased risk of osteoporosis and osteopenia, blood Cd concentration may not. Therefore, compared to blood Cd concentration, urine Cd concentration may be more reliable as a risk factor for osteoporosis and osteopenia. This result should be interpreted with caution. Currently. research on the relationship between Cd concentration and osteoporosis and osteopenia is limited, thus, further large, high-quality prospective studies are required to elucidate the relationship between Cd concentration and osteoporosis and osteopenia.

Exposure to heavy metals and the risk of osteopenia or osteoporosis: a systematic review and meta-analysis

The relationship between heavy metal exposure and risk of osteopenia or osteoporosis has biological plausibility, yet it remains inconclusive; therefore, we conducted a systematic review and meta-analysis to evaluate the associations between exposure to heavy metals (i.e., cadmium, lead, and mercury) and the risk of osteopenia or osteoporosis. Databases of MEDLINE, Embase, Scopus, and Web of Science were searched through November 2019, to identify studies that evaluated the relationship between exposure to cadmium, lead, and mercury and risk of osteopenia or osteoporosis in adults. Fourteen eligible studies were included. Effect sizes expressed as pooled odds ratios (OR) and 95% confidence intervals (CI) were estimated using weighted random-effect models. Exposure to cadmium (OR = 1.35; 95% CI: 1.17 to 1.56; P ≤ 0.001) and lead (OR = 1.15; 95% CI: 1.00 to 1.32; P = 0.05) was associated with an increased risk of osteopenia or osteoporosis, unlike mercury. Subgroup analyses showed cadmium exposure increased the risk of osteopenia or osteoporosis in older (> 65 yrs.; OR = 1.43; 95%CI: 1.08 to 1.88, P = 0.01) compared with younger (18-65 yrs.; OR = 1.24; 95% CI: 1.02 to 1.52, P = 0.03) adults. Also, lead exposure increased the risk in men (OR = 1.55; 95% CI: 1.15 to 2.09, P = 0.007) unlike in women. By contrast to urinary levels, blood (OR = 1.26; 95% CI: 1.08 to 1.47, P = 0.003) and dietary (OR = 1.46; 95% CI: 1.28 to 1.67, P < 0.001) levels of cadmium were associated with an increased risk of osteopenia or osteoporosis. Exposure to cadmium and lead may be associated with an increased risk of osteopenia or osteoporosis, although high heterogeneity was detected.

Per- and poly-fluoroalkyl substances and bone mineral density: Results from the Bayesian weighted quantile sum regression

Per- and poly-fluoroalkyl substances (PFAS) are chemicals, detected in 95% of Americans, that induce osteotoxicity and modulate hormones, thereby influencing bone health. Previous studies found associations between individual PFAS and bone mineral density in adults but did not analyze their combined effects.

OBJECTIVE

To extend weighted quantile sum (WQS) regression to a Bayesian framework (Bayesian extension of the WQS regression [BWQS]) and determine the association between a mixture of serum PFAS and mineral density in lumbar spine, total, and neck femur in 499 adults from the 2013 to 2014 National Health and Nutrition Examination Survey (NHANES).

METHODS

We used BWQS to assess the combined association of eight PFAS, as a mixture, with bone mineral density in adults. As secondary analyses, we focused on vulnerable populations (men over 50 years and postmenopausal women). Analyses were adjusted for sociodemographic factors. Sensitivity analyses included bone mineral density associations with individual compounds and results from WQS regressions.

RESULTS

The mean age was 55 years old (SD = 1) with average spine, total, and neck femur mineral densities of 1.01 (SD = 0.01), 0.95 (SD = 0.01), and 0.78 (SD = 0.01) gm/cm2, respectively. PFAS mixture levels showed no evidence of association with mineral density (spine: β = -0.004; 95% credible interval [CrI] = -0.04, 0.04; total femur: β = 0.002; 95% CrI = -0.04, 0.05; femur neck: β = 0.005; 95%CrI = -0.03, 0.04) in the overall population. Results were also null in vulnerable populations. Findings were consistent across sensitivity analyses.

CONCLUSIONS

We introduced a Bayesian extension of WQS and found no evidence of the association between PFAS mixture and bone mineral density.

Environmental mixtures and children's health: identifying appropriate statistical approaches

PURPOSE OF REVIEW

Biomonitoring studies have shown that children are constantly exposed to complex patterns of chemical and nonchemical exposures. Here, we briefly summarize the rationale for studying multiple exposures, also called mixture, in relation to child health and key statistical approaches that can be used. We discuss advantages over traditional methods, limitations and appropriateness of the context.

RECENT FINDINGS

New approaches allow pediatric researchers to answer increasingly complex questions related to environmental mixtures. We present methods to identify the most relevant exposures among a high-multitude of variables, via shrinkage and variable selection techniques, and identify the overall mixture effect, via Weighted Quantile Sum and Bayesian Kernel Machine regressions. We then describe novel extensions that handle high-dimensional exposure data and allow identification of critical exposure windows.

SUMMARY

Recent advances in statistics and machine learning enable researchers to identify important mixture components, estimate joint mixture effects and pinpoint critical windows of exposure. Despite many advantages over single chemical approaches, measurement error and biases may be amplified in mixtures research, requiring careful study planning and design. Future research requires increased collaboration between epidemiologists, statisticians and data scientists, and further integration with causal inference methods.

The association between cumulative cadmium intake and osteoporosis and risk of fracture in a Chinese population

Bone is one of the target organs for cadmium toxicity. However, few studies have shown the association between cumulative cadmium intake and prevalence of osteoporosis and bone fracture. In the present study, we evaluated the association between cumulative cadmium intake and osteoporosis and risk of fracture in a Chinese population. A total of 790 subjects (488 women and 302 men) living in a control area and two cadmium-polluted areas were included. The cumulative cadmium intake was estimated by a food survey. The bone mineral density was determined by using single-photon absorptiometry. The cumulative cadmium intakes were 0.48, 2.14, and 11.00 g for men, and 0.42, 2.11, and 11.12 g in women in control, and moderately and heavily polluted areas, respectively. In women, the odds ratios (ORs) of subjects with a cadmium intake between 2.21 and 10.63 g and >10.63 g were 1.30 (95% CI: 0.58-2.94) and 2.36 (95% CI: 1.14-5.16), compared with those with a cadmium intake < 0.58 g after adjusting to the confounders for osteoporosis. The ORs of subjects with a cadmium intake >10.63 g were 2.34 (95% CI: 1.23-4.38) for all of the women and 2.62 (95% CI: 1.02-5.58) in women ≥ 60 years old, compared with those with a cadmium intake <10.63 g after adjusting to the confounders for bone fractures. In men, similar trends were observed, but no statistical significance was found. In addition, those subjects with renal tubular dysfunction showed high risk of bone fracture. Our results indicate that a high level of cumulative cadmium intake is associated with an increased rate of osteoporosis and fractures among women.

Du-Zhong (Eucommia ulmoides Oliv.) Cortex Extract Alleviates Lead Acetate-Induced Bone Loss in Rats

The purpose of this study was to evaluate the protective effect of Du-Zhong cortex extract (DZCE) on lead acetate-induced bone loss in rats. Forty female Sprague-Dawley rats were randomly divided into four groups: group I (control) was provided with distilled water. Group II (PbAc) received 500 ppm lead acetate in drinking water for 60 days. Group III (PbAc+DZCE) received 500 ppm lead acetate in drinking water, and given intragastric DZCE (100 mg/kg body weight) for 60 days. Group IV (DZCE) was given intragastric DZCE (100 mg/kg body weight) for 60 days. The bone mineral density, serum biochemical markers, bone histomorphology, and bone marrow adipocyte parameters were analyzed using dual-energy X-ray absorptiometry, biochemistry, histomorphometry, and histopathology, respectively. The results showed that the lumbar spine and femur bone mineral density was significantly decreased in PbAc group compared with the control (P < 0.05); however, this decrease was inhibited by the intake of Du-Zhong cortex extract (P < 0.05, vs. PbAc group; P > 0.05, vs. control and DZCE group). Serum calcium and serum phosphorus in the PbAc+DZCE group were greater than that in the PbAc group (P < 0.05). The PbAc group had higher ALP, osteocalcin, and RANKL than the control group (P < 0.01), and they were significantly lower in the PbAc+DZCE group compared with the PbAc group. There were no significant differences of ALP, osteocalcin, and RANKL among the PbAc+DZCE, control, and DZCE groups (P > 0.05). Serum OPG and OPG/RANKL ration were significantly higher in the PbAc+DZCE group than that in the PbAc group (P < 0.05). The bone histomorphometric analyses showed that bone volume and trabecular thickness in the femoral trabecular bone were significantly lower in the PbAc group than that in the control group, but those were restored in the PbAc+DZCE groups. The bone marrow adipocyte number, percent adipocyte volume per tissue volume (AV/TV), and mean adipocyte diameter were significantly increased in the PbAc group compared to the control (P < 0.01), and those were restored in the PbAc+DZCE group. The differences of those parameters between PbAc+DZCE, DZCE, and the control group were not significant. The results above indicate that the Du-Zhong cortex extract has protective effects on both stimulation of bone formation and suppression of bone resorption in lead-exposed rats, therefore, Du-Zhong cortex extract has the potential to prevent or treat osteoporosis resulting from lead expose.

Endocrine Disruptors of the Bisphenol and Paraben Families and Bone Metabolism

After menopause, when estrogen levels decrease, there is room for the activity of anthropogenic substances with estrogenic properties – endocrine disruptors (EDs) – that can interfere with bone remodeling and changes in calcium-phosphate metabolism. Selected unconjugated EDs of the bisphenol group – BPA, BPS, BPF, BPAF, and the paraben family – methyl-, ethyl-, propyl-, butyl-, and benzyl-parabens – were measured by high performance liquid chromatography-tandem mass spectrometry in the plasma of 24 postmenopausal women. Parameters of calcium-phosphate metabolism and bone mineral density were assessed. Osteoporosis was classified in 14 women, and 10 women were put into the control group. The impact of EDs on calcium-phosphate metabolism was evaluated by multiple linear regressions. In women with osteoporosis, concentrations of BPA ranged from the lower limit of quantification (LLOQ) – 104 pg/ml and methyl paraben (MP) from LLOQ – 1120 pg/ml. The alternative bisphenols BPS, BPF and BPAF were all under the LLOQ. Except for MP, no further parabens were detected in the majority of samples. The multiple linear regression model found a positive association of BPA (β=0.07, p<0.05) on calcium (Ca) concentrations. Furthermore, MP (β=-0.232, p<0.05) was negatively associated with C-terminal telopeptide. These preliminary results suggest that these EDs may have effects on calcium-phosphate metabolism.

Perfluoroalkyl substances, bone density, and cardio-metabolic risk factors in obese 8-12 year old children: A pilot study

BACKGROUND AND OBJECTIVE

Perfluoroalkyl substances (PFASs), including perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA), have been associated with adverse bone, and metabolic changes in adults. However association of PFASs with bone health in children is understudied. Considering their role as endocrine disruptors, we examined relationships of four PFASs with bone health in children.

METHODS

In a cross sectional pilot study, 48 obese children aged 8-12 years were enrolled from Dayton's Children Hospital, Ohio. Anthropometric, clinical and biochemical assessments of serum were completed. Serum PFASs were measured by UPLC-ESI-MS/MS. In a subset of 23 children, bone health parameters were measured using calcaneal quantitative ultrasound (QUS).

RESULTS

While PFASs exposure was associated with a consistent negative relationship with bone health parameters, among four PFASs tested, only PFNA showed a significant negative relationship with bone parameter (β [95% CI], = - 72.7 [- 126.0, - 19.6], p = .010). PFNA was also associated with raised systolic blood pressure (p = .008), low density lipoprotein cholesterol (LDL-C; p < .001), and total cholesterol (TC; p = .014). In addition, both PFOA and PFOS predicted elevation in LDL-C, and PFOA predicted increased TC, as well. In this analysis, PFASs were not strongly related to thyroid hormones, 25-hydroxy vitamin D, liver enzymes, or glucose homeostasis.

CONCLUSION

PFASs exposure in obese children may play a role in adverse skeletal and cardiovascular risk profiles.

Perfluorooctanoic acid induces mitochondrial dysfunction in MC3T3-E1 osteoblast cells

Perfluorooctanoic acid (PFOA), a stable organic perfluorinated compound, is an emerging persistent organic pollutant, found widely in human and wildlife populations. Recent evidence suggests that exposure to environmental toxicants can be associated with higher risks of osteoporosis and fractures. We studied the cellular toxicology of PFOA in MC3T3-E1osteoblast cells. To examine the effect of PFOA, we measured cell viability, reactive oxygen species (ROS), mitochondrial superoxide, and mitochondrial parameters including adenosine triphosphate (ATP) level, mitochondrial membrane potential (MMP), cardiolipin content, and cytochrome c release in MC3T3-E1 cells. Incubating MC3T3-E1 cells in different concentrations of PFOA for 48 h resulted in a concentration-dependent decrease in cell viability and significant inductions of ROS and mitochondrial superoxide. Moreover, PFOA induced MMP collapse, cardiolipin peroxidation, cytochrome c release, and decreased ATP levels, which in turn induced apoptosis or necrosis. When osteoblast differentiation markers were assessed, PFOA treatment caused a significant reduction in alkaline phosphatase activity, collagen synthesis, and mineralization in the cells. In summary, we found an ROS- and mitochondria-mediated pathway for the induction of cell damage by PFOA in MC3T3-E1 cells. Together, our results indicate that mitochondrial toxicity could be a plausible mechanism for the toxic effects of PFOA on osteoblast function.

Environmental Factors Impacting Bone-Relevant Chemokines

Chemokines play an important role in normal bone physiology and the pathophysiology of many bone diseases. The recent increased focus on the individual roles of this class of proteins in the context of bone has shown that members of the two major chemokine subfamilies-CC and CXC-support or promote the formation of new bone and the remodeling of existing bone in response to a myriad of stimuli. These chemotactic molecules are crucial in orchestrating appropriate cellular homing, osteoblastogenesis, and osteoclastogenesis during normal bone repair. Bone healing is a complex cascade of carefully regulated processes, including inflammation, progenitor cell recruitment, differentiation, and remodeling. The extensive role of chemokines in these processes and the known links between environmental contaminants and chemokine expression/activity leaves ample opportunity for disruption of bone healing by environmental factors. However, despite increased clinical awareness, the potential impact of many of these environmental factors on bone-related chemokines is still ill defined. A great deal of focus has been placed on environmental exposure to various endocrine disruptors (bisphenol A, phthalate esters, etc.), volatile organic compounds, dioxins, and heavy metals, though mainly in other tissues. Awareness of the impact of other less well-studied bone toxicants, such as fluoride, mold and fungal toxins, asbestos, and chlorine, is also reviewed. In many cases, the literature on these toxins in osteogenic models is lacking. However, research focused on their effects in other tissues and cell lines provides clues for where future resources could be best utilized. This review aims to serve as a current and exhaustive resource detailing the known links between several classes of high-interest environmental pollutants and their interaction with the chemokines relevant to bone healing.

Exploratory analysis of the potential relationship between urinary molybdenum and bone mineral density among adult men and women from NHANES 2007-2010

Human exposure to molybdenum (Mo) may play a role in reducing bone mineral density (BMD) by interfering with steroid sex hormone levels. To begin to address gaps in the literature on this topic, the potential relationship between urinary Mo (U-Mo) and BMD at the femoral neck (FN-BMD) and lumbar spine (LS-BMD) was explored in a sample of 1496 adults participating in the 2007-2010 cycles of the National Health and Nutrition Examination Survey. Associations were assessed using multiple linear regression models stratified on sex and age. In adjusted models for 50-80+ year-old women, there was a statistically significant inverse relationship between natural log-U-Mo and LS-BMD (p-value: 0.002), and a statistically significant dose-dependent decrease in LS-BMD with increasing U-Mo quartiles (trend p-value: 0.002). A suggestive (trend p-value: 0.08), dose-dependent decrease in FN-BMD with increasing U-Mo quartiles was noted in this group of women as well. All other adjusted models revealed no statistically significant or suggestive relationships between U-Mo and FN-BMD or LS-BMD. Bone health is important for overall human health and well-being and, given the exploratory nature of this work, additional studies are needed to confirm the results in other populations, and clarify the potential underlying mechanisms of Mo on BMD.

Relationship between Blood Mercury Concentration and Bone Mineral Density in Korean Men in the 2008-2010 Korean National Health and Nutrition Examination Survey

Background

The results of previous studies on the association between blood mercury (Hg) and bone mineral density (BMD) are inconsistent. We therefore used a large-scale nationwide representative sample of Korean men to investigate the relationship between these two parameters.

Methods

A nationwide cross-sectional study was conducted using data from the 2008 to 2010 Korean National Health and Nutrition Examination Survey to evaluate the relationship between blood Hg and BMD and the prevalence of osteopenia or osteoporosis in 1,190 men over 50 years of age. BMD was measured by dual-energy X-ray absorptiometry. Osteopenia and osteoporosis were diagnosed for each body site according to World Health Organization T-score criteria.

Results

After adjusting for age, body mass index, caloric energy and calcium intake, vitamin D levels, fish consumption, alcohol consumption, smoking, and exercise, quartiles of blood Hg were positively associated with femur neck T-scores in multiple linear regression analysis (β=0.06, P-value=0.03). Compared with the lowest blood Hg quartile, the odds ratios and 95% confidence intervals for diagnosis of osteopenia or osteoporosis in the second and fourth quartiles were 0.63 (0.41–0.99) and 0.57 (0.36–0.91), respectively, in the femur neck after adjusting for the same co-variables.

Conclusion

High blood Hg levels were associated with reduced odds of decreased femur neck BMD in Korean men. However, subgroup analysis did not show a significant protective effect of blood Hg on osteoporotic fractures. Further research is necessary to clarify the association between blood Hg and BMD.

Association between urinary lead and bone health in a general population from Taiwan

Lead accumulates in adult bones for many decades; previous studies have shown lead's detrimental effects on osteoblast and osteoclast activity in association with bone remodeling. Osteoporosis is a disease of the bones resulting in low bone mass that induces fragile bones and hence susceptibility of fracture. We estimated the association between urinary lead (U-Pb) levels and bone health in adults participating in the third Nutrition and Health Survey in Taiwan (NAHSIT) from 2005 to 2008. A total of 398 participants were divided into normal (T-score>-1), osteopenic (T-score between -1 and -2.5), or osteoporotic (T-score<-2.5) groups according to the results of bone mineral density (BMD) measurements. Heavy metals were measured in urine specimens using inductively coupled plasma-mass spectrometry. In the multivariable logistic regression analysis, age (OR=1.08; 95% CI=1.05-1.10), former smokers (OR=2.95; 95% CI=1.22-7.11) and higher U-Pb levels than upper tertile (OR=2.30; 95% CI=1.19-4.48) were associated with osteopenia/osteoporosis. Furthermore, age (OR=1.06; 95% CI=1.02-1.10) and higher U-Pb levels (OR=2.81; 95% CI=1.13-6.97) were significantly associated with osteopenia and osteoporosis in women. These results suggest that adults, particularly in women, with higher U-Pb levels may have increased odds of osteopenia and osteoporosis.

Multi-Elemental Profiling of Tibial and Maxillary Trabecular Bone in Ovariectomised Rats

Atomic minerals are the smallest components of bone and the content of Ca, being the most abundant mineral in bone, correlates strongly with the risk of osteoporosis. Postmenopausal women have a far greater risk of suffering from OP due to low Ca concentrations in their bones and this is associated with low bone mass and higher bone fracture rates. However, bone strength is determined not only by Ca level, but also a number of metallic and non-metallic elements in bone. Thus, in this study, the difference of metallic and non-metallic elements in ovariectomy-induced osteoporosis tibial and maxillary trabecular bone was investigated in comparison with sham operated normal bone by laser ablation inductively-coupled plasma mass spectrometry using a rat model. The results demonstrated that the average concentrations of ²⁵Mg, ²⁸Si, ³⁹K, ⁴⁷Ti, ⁵⁶Fe, ⁵⁹Co, ⁷⁷Se, ⁸⁸Sr, ¹³⁷Ba, and ²⁰⁸Pb were generally higher in tibia than those in maxilla. Compared with the sham group, Ovariectomy induced more significant changes of these elements in tibia than maxilla, indicating tibial trabecular bones are more sensitive to changes of circulating estrogen. In addition, the concentrations of ²⁸Si, ⁷⁷Se, ²⁰⁸Pb, and Ca/P ratios were higher in tibia and maxilla in ovariectomised rats than those in normal bone at all time-points. The present study indicates that ovariectomy could significantly impact the element distribution and concentrations between tibia and maxilla.

Association of Perfluoroalkyl Substances, Bone Mineral Density, and Osteoporosis in the U.S. Population in NHANES 2009-2010

BACKGROUND

Perfluoroalkyl substances (PFASs), including perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA), are detectable in the serum of 95% of the U.S.

OBJECTIVE

Considering the role of PFASs as endocrine disruptors, we examined their relationships with bone health.

METHODS

The association between serum PFAS concentration and bone mineral density at total femur (TFBMD), femoral neck (FNBMD), lumbar spine (LSBMD), and physician-diagnosed osteoporosis was assessed in 1,914 participants using data from the National Health and Nutritional Examination Survey 2009-2010.

RESULTS

The mean age of the participants was 43 years. Men had higher serum PFAS concentrations than women (p < 0.001) except for PFNA. In both sexes, serum PFOS concentrations were inversely associated with FNBMD (p < 0.05). In women, significant negative associations were observed for natural log (ln)-transformed PFOS exposure with TFBMD and FNBMD, and for ln-transformed PFOA exposure with TFBMD (p < 0.05). In postmenopausal women, serum PFOS was negatively associated with TFBMD and FNBMD, and PFNA was negatively associated with TFBMD, FNBMD, and LSBMD (all p < 0.05). With one log unit increase in serum PFOA, PFHxS, and PFNA, osteoporosis prevalence in women increased as follows: [adjusted odds ratios (aORs)] 1.84 (95% CI: 1.17, 2.905), 1.64 (95% CI: 1.14, 2.38), and 1.45 (95% CI: 1.02, 2.05), respectively. In women, the prevalence of osteoporosis was significantly higher in the highest versus the lowest quartiles of PFOA, PFHxS, and PFNA, with aORs of 2.59 (95% CI: 1.01, 6.67), 13.20 (95% CI: 2.72, 64.15), and 3.23 (95% CI: 1.44, 7.21), respectively, based on 77 cases in the study sample.

CONCLUSION

In a representative sample of the U.S. adult population, serum PFAS concentrations were associated with lower bone mineral density, which varied according to the specific PFAS and bone site assessed. Most associations were limited to women. Osteoporosis in women was also associated with PFAS exposure, based on a small number of cases.

CITATION

Khalil N, Chen A, Lee M, Czerwinski SA, Ebert JR, DeWitt JC, Kannan K. 2016. Association of perfluoroalkyl substances, bone mineral density, and osteoporosis in the U.S. population in NHANES 2009-2010. Environ Health Perspect 124:81-87; http://dx.doi.org/10.1289/ehp.1307909.

Protective effect of zinc supplementation against cadmium-induced oxidative stress and the RANK/RANKL/OPG system imbalance in the bone tissue of rats

It was investigated whether protective influence of zinc (Zn) against cadmium (Cd)-induced disorders in bone metabolism may be related to its antioxidative properties and impact on the receptor activator of nuclear factor (NF)-κΒ (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system. Numerous indices of oxidative/antioxidative status, and Cd and Zn were determined in the distal femur of the rats administered Zn (30 and 60mg/l) or/and Cd (5 and 50mg/l) for 6months. Soluble RANKL (sRANKL) and OPG were measured in the bone and serum. Zn supplementation importantly protected from Cd-induced oxidative stress preventing protein, DNA, and lipid oxidation in the bone. Moreover, Zn protected from the Cd-induced increase in sRANKL concentration and the sRANKL/OPG ratio, and decrease in OPG concentration in the bone and serum. Numerous correlations were noted between indices of the oxidative/antioxidative bone status, concentrations of sRANKL and OPG in the bone and serum, as well as the bone concentrations of Zn and Cd, and previously reported by us in these animals (Brzóska et al., 2007) indices of bone turnover and bone mineral density. The results allow us to conclude that the ability of Zn to prevent from oxidative stress and the RANK/RANKL/OPG system imbalance may be implicated in the mechanisms of its protective impact against Cd-induced bone damage. This paper is the first report from an in vivo study providing evidence that beneficial Zn impact on the skeleton under exposure to Cd is related to the improvement of the bone tissue oxidative/antioxidative status and mediating the RANK/RANKL/OPG system.