Bone Lead Research Articles

Bone lead measurements of live condors in field to assess cumulative lead exposure.

Lead poisoning remains the leading cause of diagnosed death for critically endangered California condors, which are annually monitored for lead exposure via blood tests. Blood tests are generally reflective of acute lead exposure. Since condors are victims to both chronic and acute lead exposure, measuring bone, which in humans is reflective of years to decades worth of exposure, is a valuable biomarker. In this study, we measured bone Pb of the tibiotarsus of 64 condors in vivo using a portable x-ray fluorescence device. The average uncertainty for measurements, typically reflective of how effective the device performed, was found to be 3.8 ± 2.2µg/g bone mineral. The average bone lead level was found to be 26.7 ± 24.5µg/g bone mineral. Bone lead correlated significantly with a sum of all blood lead measures over the lifetime of each condor. In the future, bone lead can potentially be used to inform treatment planning and address the chronic health implications of lead in the species.

Improving prediction of linear regression models by integrating external information from heterogeneous populations: James-Stein estimators.

We consider the setting where (1) an internal study builds a linear regression model for prediction based on individual-level data, (2) some external studies have fitted similar linear regression models that use only subsets of the covariates and provide coefficient estimates for the reduced models without individual-level data, and (3) there is heterogeneity across these study populations. The goal is to integrate the external model summary information into fitting the internal model to improve prediction accuracy. We adapt the James-Stein shrinkage method to propose estimators that are no worse and are oftentimes better in the prediction mean squared error after information integration, regardless of the degree of study population heterogeneity. We conduct comprehensive simulation studies to investigate the numerical performance of the proposed estimators. We also apply the method to enhance a prediction model for patella bone lead level in terms of blood lead level and other covariates by integrating summary information from published literature.

Portable x-ray fluorescence for bone lead measurement: Current approaches and future directions.

Legacy lead exposures persist as a widespread problem. Blood lead is traditionally used for lead exposure surveillance; however, bone lead proves to be a cheaper, more accessible, and more revealing tool for surveillance that can be measured using portable x-ray fluorescence techniques. We outline how this approach excels for bone lead measurements. Portable XRF offers quick, non-invasive in vivo quantification of bone lead. Compared to traditional KXRF systems, pXRF is limited to cortical bone but allows for quicker and similar results. Current methodologies of lead exposure need re-evaluation as lead-related disease burden and trends are dependent on both cumulative and acute impacts. We examined the evolution of XRF techniques for measuring bone lead, comparing current methods with previous ones. We assessed their accuracy, identified limitations, and discussed potential advances in future techniques. Legacy lead exposures call for a revitalization of lead surveillance methods, and pXRF measurement of bone lead offers such a solution.

The feasibility of K XRF bone lead measurements in mice assessed using 3D-printed phantoms

This article describes the development of a system for in vivo measurements of lead body burden in mice using 109Cd K x-ray fluorescence (XRF). This K XRF system could facilitate early-stage studies on interventions that ameliorate or reverse organ tissue damage from lead poisoning by reducing animal numbers through a cross-sectional study approach. A novel mouse phantom was developed based on a mouse atlas and 3D-printed using PLA plastic with plaster of Paris ’bone’ inserts. PLA plastic was found to be a good surrogate for soft tissue in XRF measurements and the phantoms were found to be good models of mice. As expected, lead detection limits varied with mouse size, mouse orientation, and mouse position with respect to the source and detector. The work suggests that detection limits of 10 to 20 μg Pb per g bone mineral may be possible for a 2 to 3 hour XRF measurement in a single animal, an adequate limit for some pre-clinical studies. The 109Cd K XRF mouse measurement system was also modeled using the Monte Carlo code MCNP. The combination of experiment and modeling found that contrary to expectation, accurate measurements of lead levels in mice required calibration using mouse-specific calibration standards due to the coherent scatter peak normalization failing when small animals are measured. MCNP modeling determined that this was because the coherent scatter signal from soft tissue, which until now has been assumed negligible, becomes significant when compared to the coherent scatter signal in bone in small animals. This may have implications for some human measurements. This work suggests that 109Cd K x-ray fluorescence measurements of lead body burden are precise enough to make the system feasible for small animals if appropriately calibrated. Further work to validate the technology’s measurement accuracy and performance in vivo will be required.

Do we underestimate risk of cardiovascular mortality due to lead exposure?

BackgroundStudies using data from the National Health and Nutrition Examination Survey-III (NHANES-III) have demonstrated significant prospective associations between blood lead levels and increased mortality. Bone lead represents cumulative lead burden and thus is a better biomarker for assessing chronic impacts, but its in vivo assessment requires special K-x-ray fluorescence (KXRF) instrumentation. Our team recently developed an algorithm predicting bone lead levels from a combination of blood lead levels, age and other socioeconomic and behavioral variables. We examined the associations of our algorithm-estimated bone lead levels and mortality in NHANES-III. MethodsWe included 11,628 adults followed up to December 31, 2019. Estimated tibia lead and patella lead levels were calculated using our prediction algorithms. We used survey-weighted Cox proportional hazards models to compute hazard ratios (HRs) and 95 % confidence intervals (CIs). ResultsDuring the median follow-up of 26.8 years, 4900 participants died (mortality rate = 1398 per 100,000 adults/year). Geometric means (95 % CIs) of blood lead, predicted tibia lead, and predicted patella lead were 2.69 μg/dL (2.54, 2.84), 6.73 μg/g (6.22, 7.25), and 16.3 μg/g (15.9, 16.8), respectively. The associations for all-cause mortality were similar between blood lead and bone lead. However, the associations for cardiovascular mortality were much greater with predicted bone lead markers compared to blood lead: for comparing participants at the 90th vs. 10th percentiles of exposure, HR = 3.32 (95 % CI: 1.93–5.73) for tibia lead, 2.42 (1.56–3.76) for patella lead, 1.63 (1.25–2.14) for blood lead. The population attributable fractions for cardiovascular disease mortality if everyone's lead concentrations were declined to the 10th percentiles were 45.8 % (95 % CI: 28.1–59.4) for tibia lead, 33.1 % (18.1–45.8) for patella lead, and 22.8 % (10.4–33.8) for blood lead. ConclusionsThese findings suggest that risk assessment for cardiovascular mortality based on blood lead levels may underestimate the true mortality risk of lead exposure.

Concentrations of lead in pinniped bones confirm Galapagos as a relatively unpolluted environment

Lead (Pb) is a trace element that is naturally present in arid regions but it is also released to the marine environment by anthropogenic industrial emissions. Here, we assessed Pb concentrations in bone samples of four pinniped species: the Galapagos sea lion Zalophus wollebaeki, sampled in Galapagos archipelago, the monk seal Monachus monachus from Mauritania, and the South American fur seal Arctocephalus australis and the South American sea lion Otaria flavescens, from Uruguay, and investigate potential geographic differences. Concentrations of lead in the samples from Galapagos were lower than those detected in samples from Mauritania and Uruguay, indicating that the Galapagos archipelago is a comparatively pristine spot for this toxic element as related to the other two areas. The waters of Mauritania and Uruguay are likely affected by the inputs of lead brought by the desert dust and released by the local industry, respectively. This study supports the use of bone to assess lead concentrations in biota, as well as the use of pinnipeds as bioindicators of marine pollution.

Long-term stability of hydroxyapatite bone phantoms for the calibration of in vivo x-ray fluorescence spectrometry-based systems of bone lead and strontium quantification

Hydroxyapatite (HAp) phantoms have been proposed as an alternative to plaster of Paris (poP) phantoms for the calibration of x-ray fluorescence-based systems for the in vivo quantification of bone lead and strontium which employ a coherent normalization procedure. The chemical composition of the material becomes critical in the calculation, or omission, of the coherent correction factor (CCF) required in this normalization procedure. This study evaluated the long-term chemical stability of HAp phantoms. Phantoms were prepared and allowed to age for a two week period and over a seven year period in ambient conditions. The chemical composition of the phantoms was then assessed by powder x-ray diffraction. Two week old phantoms were found to be composed of HAp with only a small amount of contamination from CaHPO4·2H2O. Seven year old phantoms were found to have converted nearly completely to a carbonate-bearing apatite in the form of Ca10(PO4)6(CO3)0.75(OH)0.5 indicating that the HAp phantom material likely reacts with carbon dioxide in air over time forming a carbonate-bearing apatite. The influence of this chemical conversion was assessed at the level of relevant cross-sections. Calibration under the assumption that the material is HAp when in fact it is a carbonate-bearing apatite would result in not more than a 0.2%–2% bias in the total mass attenuation coefficient within the photon energy range of 0–100 keV. Differential scattering cross-section for coherent scattering was found to differ between HAp and carbonate-bearing apatite by 0.9%–2% for both a 35.5 keV and 88.0 keV γ-ray. This variation in the differential scattering cross-section for coherent scattering may introduce a ca. 2% bias in the CCF used within the coherent normalization-based calibration procedure. Using HAp phantoms as calibrators thus requires acknowledgement of this conversion in chemical form and possible introduction of uncertainty into the calibration procedure.

Effects of food-borne docosahexaenoic acid supplementation on bone lead mobilisation, mitochondrial function and serum metabolomics in pre-pregnancy lead-exposed lactating rats

Large bone lead (Pb) resulting from high environmental exposure during childhood is an important source of endogenous Pb during pregnancy and lactation. Docosahexaenoic acid (DHA) attenuates Pb toxicity, however, the effect of DHA on bone Pb mobilisation during lactation has not been investigated. We aimed to study the effects of DHA supplementation during pregnancy and lactation on bone Pb mobilisation during lactation and its potential mechanisms. Weaning female rats were randomly divided into control (0.05% sodium acetate) and Pb-exposed (0.05% Pb acetate) groups, after a 4-week exposure by ad libitum drinking and a subsequent 4-week washout period, all female rats were mated with healthy males until pregnancy. Then exposed rats were randomly divided into Pb and Pb + DHA groups, and the latter was given a 0.14% DHA diet, while the remaining groups were given normal feed until the end of lactation. Pb and calcium levels, bone microarchitecture, bone turnover markers, mitochondrial function and serum metabolomics were analyzed. The results showed that higher blood and bone Pb levels were observed in the Pb group compared to the control, and there was a significant negative correlation between blood and bone Pb. Also, Pb increased trabecular bone loss along with slightly elevated serum C-telopeptide of type I collagen (CTX-I) levels. However, DHA reduced CTX-I levels and improved trabecular bone microarchitecture. Metabolomics showed that Pb affected mitochondrial function, which was further demonstrated in bone tissue by significant reductions in ATP levels, Na+-K+-ATPase, Ca2+-Mg2+-ATPase and CAT activities, and elevated levels of MDA, IL-1β and IL-18. However, these alterations were partially mitigated by DHA. In conclusion, DHA supplementation during pregnancy and lactation improved bone Pb mobilisation and mitochondrial dysfunction in lactating rats induced by pre-pregnancy Pb exposure, providing potential means of mitigating bone Pb mobilisation levels during lactation, but the mechanism still needs further study.

The association between lead exposure and crime: A systematic review.

Prior research has demonstrated an association between lead exposure and criminal behavior at the population-level, however studies exploring the effect of lead exposure on criminal behavior at the individual-level have not been reviewed systematically. The intent of this study is to complete a systematic review of all studies assessing individual-level exposures to lead and the outcomes of crime and antisocial behavior traits. We included peer reviewed studies that were published prior to August 2022 and were classified as cohort, cross-sectional, or case-control. Studies measuring the outcomes of crime, delinquency, violence, or aggression were included. The following databases were searched using a standardized search strategy: ProQuest Environmental Science Database, PubMed, ToxNet and the Public Affairs Information Service (PAIS). Seventeen manuscripts met our inclusion criteria. Blood lead was measured in 12 studies, bone lead in 3 studies, and dentine lead levels in 2 studies. This systematic review identified a wide range of diverse outcomes between exposure to lead at multiple windows of development and later delinquent, criminal and antisocial behavior. A review of all potential confounding variables included within each study was made, with inclusion of relevant confounders into the risk of bias tool. There is limited data at the individual level on the effects of prenatal, childhood, and adolescent lead exposure and later criminal behavior and more evidence is necessary to evaluate the magnitude of the associations seen in this review. Our review, in conjunction with the available biological evidence, suggests that an excess risk for criminal behavior in adulthood exists when an individual is exposed to lead in utero or in the early years of childhood. The authors report no conflict of interest and no funding source. Clinical trial registration: PROSPERO ID: CRD42021268379.

Lead exposure of mainland Australia's top avian predator

Lead (Pb) toxicity, through ingestion of lead ammunition in carcasses, is a threat to scavenging birds worldwide, but has received little attention in Australia. We analyzed lead exposure in the wedge-tailed eagle (Aquila audax), the largest raptor species found in mainland Australia and a facultative scavenger. Eagle carcasses were collected opportunistically throughout south-eastern mainland Australia between 1996 and 2022. Lead concentrations were measured in bone samples from 62 animals via portable X-ray fluorescence (XRF). Lead was detected (concentration >1 ppm) in 84% (n = 52) of the bone samples. The mean lead concentration of birds in which lead was detected was 9.10 ppm (±SE 1.66). Bone lead concentrations were elevated (10–20 ppm) in 12.9% of samples, and severe (>20 ppm) in 4.8% of samples. These proportions are moderately higher than equivalent data for the same species from the island of Tasmania, and are comparable to data from threatened eagle species from other continents. Lead exposure at these levels is likely to have negative impacts on wedge-tailed eagles at the level of the individual and perhaps at a population level. Our results suggest that studies of lead exposure in other Australian avian scavenger species are warranted.

Early childhood lead exposure is not reflected in adult bone lead: Results of a sub-cohort of African American women in the Cincinnati lead study

IntroductionPb in bone may serve as a biomarker for cumulative Pb dose over decades. We hypothesized that adult female bone Pb concentrations (BoPb) would be significantly associated with average childhood blood Pb levels (BlPb) in a birth cohort exposed to relatively high levels of Pb from Pb paint residues. Methods94 African American women with a mean age of 32.7 years were recruited from the Cincinnati Lead Study (CLS) cohort. Subjects were born to women residing where there had been a high incidence of childhood Pb poisoning. Biomarkers of Pb exposure were serial BlPb concentrations spanning the prenatal period to approximately 6.5 years of age. BoPb was assessed in the tibia using the McMaster 109Cd K-XRF fourth generation system. Covariates included nutritional variables related to bone health. ResultsBlPb concentrations began to rise around 6 months of age and declined at later ages. Study participants were obese with a mean Body Mass Index of 34.4 and suboptimal vitamin D status as indicated by a mean 25-OH-D of 18.5 ng/ml. Average tibia Pb was −2.0 ± 8.6 μgPb/g bone mineral. In multiple linear regression, there was no significant association between BoPb at approximately age 30 and childhood cumulative BlPb(CumBlPb). DiscussionCollectively, BoPb of this group of subjects was not detectable. We suggest that the reason these subjects’ BoPb did not reflect their early exposure was that a significantly smaller proportion of Pb body burden resides in bone in young children. As the child grows what Pb there was in bone is diluted and any remaining signal is weak. It has been claimed that BoPb in older children, adolescents, and adults can recapitulate historical exposure to Pb during earlier development; however, in some populations, BoPb at later ages may not be an adequate biomarker to capture childhood exposure to Pb.

Bone lead variability in bone repository skeletal samples measured with portable x-ray fluorescence

Bone lead serves as a better, more accessible biomarker to many communities experiencing chronic exposure to lead. A new method using low energy x-ray fluorescence in a handheld device (portable XRF) allows us to measure this chronic biomarker in only a few minutes. However, many unknowns remain about this biomarker measured using a new low energy x-ray technique. The low energy of the new method was theorized to measure a slightly different portion of the bone than previous techniques, which could influence measurements at different bone sites and types. We tested how bone measurements varied across five bone sites: mid-tibial shaft, proximal tibia, distal tibia (ankle), ilium, and cranium. We found bone lead measurements are not significantly different between skeletal elements when measured using a portable XRF. On average, bone lead in the repository samples was measured to be 21.6 ± 21.3 μg/g with an XRF detection limit of 2.1 ± 0.5 μg/g. Cumulative lead exposure can be effectively measured using the portable XRF on a variety of bone types, but the tibia should be preferentially measured to compare between studies and individuals.

A Western Diet Pattern Is Associated with Higher Concentrations of Blood and Bone Lead among Middle-Aged and Elderly Men

A Western Diet Pattern Is Associated with Higher Concentrations of Blood and Bone Lead among Middle-Aged and Elderly Men

The Influence of Environmental Exposure to Heavy Metals on the Occurrence of Selected Elements in the Maxillary Bone.

The elemental composition of the body's calcified tissues may reflect the environmental exposure of the population to heavy metals. The aim of the study was to assess whether the elemental composition of the maxillary bone from individuals belonging to a given population reflects the environmental exposure of this population to lead and cadmium. The research material consisted of cortical bone from the anterolateral walls of the maxilla collected from 126 patients during Caldwell-Luc maxillary sinus surgery on residents of two cities differing in terms of the lead and cadmium pollution of the natural environment. The content levels of lead, cadmium, iron, manganese, chromium, copper, and iron were determined by using atomic absorption spectrophotometry. The content levels of lead and cadmium in the samples of the maxillary bones of residents of Bielsko-Biala were 3.26 ± 2.42 µg/g and 0.74 ± 0.38 µg/g, respectively, whereas in the samples from the residents of Katowice, they were 7.66 ± 2.79 µg/g and 1.12 ± 0.08 µg/g, respectively. It was found that the lead and cadmium levels in the maxillary bone corresponded to the environmental exposure to these heavy metals in the place of residence, which was proven here via the example of the residents of two cities with different concentrations of these heavy metals in the air over long time periods. Additionally, higher content levels of essential metals such as manganese, chromium, copper, and iron are characteristic of the maxillary bone samples of residents of the area that is more polluted with heavy metals.

Expanding the use of portable XRF to monitor lead exposure in an Australian duck species two decades after a ban on lead shot

There is growing worldwide recognition of the threat posed by toxic lead for wildlife and humans. Lead toxicity from ammunition has been shown to be a threat to waterbirds across the globe. Lead shot was banned for all waterfowl hunting in Victoria, Australia, in 2002. However, no assessments of lead exposure in Australian waterfowl have been published since the 1990s. Our aim was to estimate contemporary lead exposure via measuring bone lead concentrations in a harvested dabbling duck, the Pacific black duck (Anas superciliosa). We collected wings from 77 Pacific black ducks, spanning 2018 (n = 30) and 2021 (n = 47), from nine sites with long-term histories of regular waterfowl hunting. We sought to validate portable X-ray fluorescence (XRF) for this purpose by taking a piece of humerus bone from each bird, and measuring lead concentration (mg/kg), first via non-destructive XRF and then via destructive inductively coupled plasma mass spectrometry (ICP-MS) and validated the relationship via regression analysis. Portable XRF bone lead measurement demonstrated a strong correlation with ICP-MS results using root-transformed regression (R2 = 0.85). Greater than 92 % of ducks had only background lead exposure (<10 mg/kg). When compared to historical studies in the same species at similar field sites from the 1990s, lead exposure levels were considerably lower, with mean lead concentrations ∼2-fold lower (3.7 c.f. 7.7 mg/kg), and the frequency of birds with severe lead exposure (>20 mg/kg) ∼3-fold lower (2.6 c.f. 7.5 %). Our results confirm that portable XRF is a useful option for measurement of bone lead in Australasian waterbird species. Our findings also demonstrate that a ban on the use of lead shot around 20 years ago has been associated with a substantial reduction in lead exposure in at least one species of waterfowl.

Epigenetic Biomarkers of Lead Exposure and Cardiovascular Disease: Prospective Evidence in the Strong Heart Study.

Background Lead is a cardiotoxic metal with a variety of adverse health effects. In the absence of data on bone lead exposure, epigenetic biomarkers can serve as indicators of cumulative lead exposure and body burden. Herein, we leveraged novel epigenetic biomarkers of lead exposure to investigate their association with cardiovascular disease (CVD) incidence and mortality. Methods and Results Blood DNA methylation was measured using the Illumina MethylationEPIC BeadChip among 2231 participants of the Strong Heart Study (SHS) at baseline (1989-1991). Epigenetic biomarkers of lead levels in blood, patella, and tibia were estimated using previously identified cytosine-guanine dinucleotide (CpG) sites. CVD incidence and mortality data were available through 2017. Median concentrations of lead epigenetic biomarkers were 13.8 μg/g, 21.3 μg/g, and 2.9 μg/dL in tibia, patella, and blood, respectively. In adjusted models, the hazard ratio (HR) (95% CI) of CVD mortality per doubling increase in lead epigenetic biomarkers were 1.42 (1.07-1.87) for tibia lead, 1.22 (0.93-1.60) for patella lead, and 1.57 (1.16-2.11) for blood lead. The corresponding HRs for incident CVD were 0.99 (0.83-1.19), 1.07 (0.89-1.29), and 1.06 (0.87-1.30). The association between the tibia lead epigenetic biomarker and CVD mortality was modified by sex (interaction P value: 0.014), with men at increased risk (HR, 1.42 [95% CI, 1.17-1.72]) compared with women (HR, 1.04 [95% CI, 0.89-1.22]). Conclusions Tibia and blood epigenetic biomarkers were associated with increased risk of CVD mortality, potentially reflecting the cardiovascular impact of cumulative and recent lead exposures. These findings support that epigenetic biomarkers of lead exposure may capture some of the disease risk associated with lead exposure.

Predicting cumulative lead (Pb) exposure using the Super Learner algorithm

Chronic lead (Pb) exposure causes long term health effects. While recent exposure can be assessed by measuring blood lead (half-life 30 days), chronic exposures can be assessed by measuring lead in bone (half-life of many years to decades). Bone lead measurements, in turn, have been measured non-invasively in large population-based studies using x-ray fluorescence techniques, but the method remains limited due to technical availability, expense, and the need for licensing radioactive materials used by the instruments. Thus, we developed prediction models for bone lead concentrations using a flexible machine learning approach--Super Learner, which combines the predictions from a set of machine learning algorithms for better prediction performance. The study population included 695 men in the Normative Aging Study, aged 48 years and older, whose bone (patella and tibia) lead concentrations were directly measured using K-shell-X-ray fluorescence. Ten predictors (blood lead, age, education, job type, weight, height, body mass index, waist circumference, cumulative cigarette smoking (pack-year), and smoking status) were selected for patella lead and 11 (the same 10 predictors plus serum phosphorus) for tibia lead using the Boruta algorithm. We implemented Super Learner to predict bone lead concentrations by calculating a weighted combination of predictions from 8 algorithms. In the nested cross-validation, the correlation coefficients between measured and predicted bone lead concentrations were 0.58 for patella lead and 0.52 for tibia lead, which has improved the correlations obtained in previously-published linear regression-based prediction models. We evaluated the applicability of these prediction models to the National Health and Nutrition Examination Survey for the associations between predicted bone lead concentrations and blood pressure, and positive associations were observed. These bone lead prediction models provide reasonable accuracy and can be used to evaluate health effects of cumulative lead exposure in studies where bone lead is not measured.

Proximal sesamoid bone microdamage is localized to articular subchondral regions in Thoroughbred racehorses, with similar fracture toughness between fracture and controls.

To determine whether proximal sesamoid bone (PSB) microdamage and fracture toughness differ between Thoroughbred racehorses sustaining PSB fracture and controls. Cadaveric case-control. Twenty-four Thoroughbred racehorses (n=12 PSB fracture, n=12 control). Proximal sesamoid bones were dissected, and gross pathological changes and morphological measurements were documented. High-speed exercise history data were evaluated. Microdamage was assessed in fracture, fracture-contralateral limb (FXCL) and control PSBs using whole bone lead uranyl acetate (LUA) staining with micro-CT imaging or basic fuchsin histological analysis. Fracture toughness mechanical testing was carried out in 3-point-bending of microbeams created from PSB flexor cortices. Data were analyzed using ordinal logistic and linear regression models. Microdamage was detected most commonly in the articular subchondral region of PSBs via LUA micro-CT and basic fuchsin histology. There were no differences in microdamage between FXCL and control PSBs. Fracture toughness values were similar for FXCL (1.31 MPa√m) and control (1.35 MPa√m) PSBs. Exercise histories were similar except that horses sustaining fracture spent a greater percentage of their careers in rest weeks. Microdamage was detected in the articular region of PSBs but was not greater in horses sustaining catastrophic PSB fracture. Fracture toughness of PSB flexor cortices did not differ between FXCL and control PSBs. Although uncommon, microdamage is localized to the articular region of Thoroughbred racehorse PSBs. Catastrophic PSB failure is not associated with lower PSB flexor cortex fracture toughness.

The Abundance of Trace Elements in Human Bone Relative to Bone Type and Bone Pathology.

As the global population ages and the proportion of individuals afflicted with musculoskeletal disease spirals upward, there is an increasing interest in understanding and preventing bone‐related diseases. Bone diseases, such as osteoporosis and osteoarthritis, are known to be influenced by a variety of factors including age, gender, nutrition, and genetics, but are also inherently linked to the human body's ability to produce biominerals of suitable quality. Because the crystal lattice structure and mineralogy of bone hydroxyapatite is surprisingly analogous to geological hydroxyapatite, trace element levels and exposure have long been proposed to influence the structure of biominerals as they do geological minerals (e.g., strontium substitution changes the crystal lattice of bone minerals, while toxic lead disrupt bone cellular processes leading to bone disease). Here, we explore the distribution of trace elements in human bones to evaluate the distribution of these elements with respect to bone type (cortical vs. trabecular) and bone disease (osteoarthritis vs. osteoporosis). We find higher concentrations of many metabolically active transition metals, as well as lead, in cortical bone compared to trabecular bone. When compared to patients who have osteoarthritis, and thus presumably normal bone minerals, osteoporosis patients have higher concentrations of scandium and chromium (Cr) in trabecular bone, and Cr and lead in cortical bone. Lower concentrations of barium and titanium are associated with osteoporotic trabecular bone. This survey is an exploratory cross‐sectional geochemical examination of several trace element concentrations previously understudied in human bone minerals.

Association between Bone Lead Concentration and Aggression in Youth from a Sub-Cohort of the Birth to Twenty Cohort.

Background: An association between blood-lead levels and aggression has been demonstrated in children and adolescent youth in South Africa. However, there are limited studies that have assessed aggression as an outcome for cumulative lead exposure using bone lead concentration. This study aims to assess the association between bone lead concentration and aggressive behaviour among a sample of youth in South Africa. Methods: Bone lead in 100 participants (53 males and 47 females) recruited and followed in the Birth to Twenty (BT20) Cohort were measured using 109 Cd-based, K-shell X-ray fluorescence (KXRF). The Buss–Perry Aggression questionnaire was used to measure aggressive behaviour. Linear regression models were fitted to determine the association between aggression score for physical, verbal, anger and hostility and bone lead, adjusting for known confounders. Results: A one-microgram-per-gram increase in bone lead was found to increase the score for all four scales of aggression, but significantly only for anger (β = 0.2 [95% CI 0.04–0.370]). Psychosocial factors such as a history of family violence and exposure to neighbourhood crime were significant predictors for aggression. Conclusions: The study provides a preliminary overview of the relationship between cumulative lead exposure and behavioural problems such as aggression. A larger sample, across exposed communities, may prove more definitive in further investigating the association between these two important public health factors and to maximize generalizability.