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Specht AJ, Hoover C, Grier T. Portable x-ray fluorescence for bone lead measurement: Current approaches and future directions. Curr Environ Health Rep 2024; 11:443-451. [PMID: 38776000 DOI: 10.1007/s40572-024-00450-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/15/2024] [Indexed: 08/15/2024]
Abstract
PURPOSE OF REVIEW 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. RECENT FINDINGS 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.
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Affiliation(s)
- Aaron J Specht
- School of Health Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN, 47907, USA.
- Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA.
| | - Christian Hoover
- Department of Epidemiology, Brown School of Public Health, Providence, RI, USA
- Harvard Injury Control Research Center, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Thomas Grier
- School of Health Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN, 47907, USA
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Bali V, Khajuria Y, Maniyar V, Rai PK, Kumar U, Ghany C, Gondal M, Singh VK. Quantitative analysis of human hairs and nails. Biophys Rev 2023; 15:401-417. [PMID: 37396444 PMCID: PMC10310683 DOI: 10.1007/s12551-023-01069-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 05/23/2023] [Indexed: 07/04/2023] Open
Abstract
Hair and nails are human biomarkers capable of providing a continuous assessment of the concentrations of elements inside the human body to indicate the nutritional status, metabolic changes, and the pathogenesis of various human diseases. Laser-induced breakdown spectroscopy (LIBS) and X-ray fluorescence (XRF) spectrometry are robust and multi-element analytical techniques able to analyze biological samples of various kinds for disease diagnosis. The primary objective of this review article is to focus on the major developments and advances in LIBS and XRF for the elemental analysis of hair and nails over the last 10-year period. The developments in the qualitative and quantitative analyses of human hair and nail samples are discussed in detail, with special emphasis on the key aspects of elemental imaging and distribution of essential and non-essential elements within the hair and nail tissue samples. Microchemical imaging applications by LIBS and XRF (including micro-XRF and scanning electron microscopy, SEM) are also presented for healthy as well as diseased tissue hair and nail samples in the context of disease diagnosis. In addition, main challenges, prospects, and complementarities of LIBS and XRF toward analyzing human hair and nails for disease diagnosis are also thoroughly discussed here.
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Affiliation(s)
- Varun Bali
- School of Physics, Shri Mata Vaishno Devi University, Katra, Jammu and Kashmir, 182320 India
| | - Yugal Khajuria
- School of Physics, Shri Mata Vaishno Devi University, Katra, Jammu and Kashmir, 182320 India
| | | | - Pradeep K. Rai
- Department of Urology and Nephrology, Opal Hospital, Kakarmatta, Varanasi, Uttar Pradesh 221005 India
| | - Upendra Kumar
- Advanced Functional Materials Laboratory, Department of Applied Sciences, IIIT Allahabad, Prayagraj, Uttar Pradesh 211005 India
| | - Charles Ghany
- Department of Engineering, Computer Science, and Physics, Mississippi College, Clinton, MS 39056 USA
| | - M.A. Gondal
- Laser Research laboratory, Physics Department, IRC- Hydrogen and Energy Storage, King Fahd University of Petroleum and Minerals, Dhahran, 31261 Saudi Arabia
| | - Vivek K. Singh
- School of Physics, Shri Mata Vaishno Devi University, Katra, Jammu and Kashmir, 182320 India
- Department of Physics, University of Lucknow, Lucknow, Uttar Pradesh 226007 India
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Specht AJ, Zhang X, Young A, Nguyen VT, Christiani DC, Ceballos DM, Allen JG, Weuve J, Nie LH, Weisskopf MG. Validation of in vivo toenail measurements of manganese and mercury using a portable X-ray fluorescence device. JOURNAL OF EXPOSURE SCIENCE & ENVIRONMENTAL EPIDEMIOLOGY 2022; 32:427-433. [PMID: 34211112 PMCID: PMC8720103 DOI: 10.1038/s41370-021-00358-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 06/17/2021] [Accepted: 06/22/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND AND OBJECTIVE Toenail metal concentrations can be used as an effective biomarker for exposure to environmental toxicants. Typically toenail clippings are measured ex vivo using inductively coupled plasma mass spectrometry (ICP-MS). X-ray fluorescence (XRF) toenail metal measurements done on intact toenails in vivo could be used as an alternative to alleviate some of the disadvantages of ICP-MS. In this study, we assessed the ability to use XRF to measure toenail metal concentrations in real-time without having to clip the toenails (i.e., in vivo) in two occupational settings for exposure assessment of manganese and mercury. MATERIALS AND METHODS The portable XRF method used a 3-min in vivo measurement of toenails prior to clipping and was assessed against ICP-MS measurement of toenail clippings taken immediately after the XRF measurement and work history for a group of welders (n = 16) assessed for manganese exposure and nail salon workers (n = 10) assessed for mercury exposure. RESULTS AND CONCLUSIONS We identified that in vivo XRF metal measurements were able to discern exposure to manganese in welders and mercury in nail salon workers. We identified significant positive correlations between ICP-MS of clippings and in vivo XRF measures of both toenail manganese (R = 0.59, p = 0.02) and mercury (R = 0.74, p < 0.001), as well as between in vivo XRF toenail manganese and work history among the welders (R = 0.55, p = 0.03). We identified in vivo XRF detection limits to be 0.5 µg/g for mercury and 2.6 µg/g for manganese. Further work should elucidate differences in the timing of exposure using the in vivo XRF method over toenail clippings and modification of measurement time and x-ray setting to further decrease the detection limit. In vivo portable, XRF measurements can be used to effectively measure toenail Mn and Hg in occupational participants in real-time during study visits and at a fraction of the cost.
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Affiliation(s)
- Aaron J Specht
- Harvard T.H. Chan School of Public Health, Boston, MA, USA.
- Purdue University, School of Health Sciences, West Lafayette, IN, USA.
| | - Xinxin Zhang
- Purdue University, School of Health Sciences, West Lafayette, IN, USA
| | - Anna Young
- Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Vy T Nguyen
- Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | | | - Diana M Ceballos
- Department of Environmental Health, Boston University, Boston, MA, USA
| | - Joseph G Allen
- Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Jennifer Weuve
- Department of Epidemiology, Boston University School of Public Health, Boston, MA, USA
| | - Linda H Nie
- Purdue University, School of Health Sciences, West Lafayette, IN, USA
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Investigating methods of normalization for X-ray fluorescence measurements of zinc in nail clippings using the TOPAS Monte Carlo code. Appl Radiat Isot 2022; 182:110151. [DOI: 10.1016/j.apradiso.2022.110151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 01/20/2022] [Accepted: 02/11/2022] [Indexed: 11/22/2022]
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Bhatia M, Specht AJ, Ramya V, Sulaiman D, Konda M, Balcom P, Sunderland EM, Qureshi A. Portable X-ray Fluorescence as a Rapid Determination Tool to Detect Parts per Million Levels of Ni, Zn, As, Se, and Pb in Human Toenails: A South India Case Study. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:13113-13121. [PMID: 34529917 PMCID: PMC8582015 DOI: 10.1021/acs.est.1c00937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Chronic exposure to inorganic pollutants adversely affects human health. Inductively coupled plasma mass spectrometry (ICP-MS) is the most common method used for trace metal(loid) analysis of human biomarkers. However, it leads to sample destruction, generation of secondary waste, and significant recurring costs. Portable X-ray fluorescence (XRF) instruments can rapidly and nondestructively determine low concentrations of metal(loid)s. In this work, we evaluated the applicability of portable XRF as a rapid method for analyzing trace metal(loid)s in toenail samples from three populations (n = 97) near the city of Chennai, India. A Passing-Bablok regression analysis of results from both methods revealed that there was no proportional bias among the two methods for nickel (measurement range ∼25 to 420 mg/kg), zinc (10 to 890 mg/kg), and lead (0.29 to 4.47 mg/kg). There was a small absolute bias between the two methods. There was a strong proportional bias (slope = 0.253, 95% CI: 0.027, 0.614) between the two methods for arsenic (below detection to 3.8 mg/kg) and for selenium when the concentrations were lower than 2 mg/kg. Limits of agreement between the two methods using Bland-Altman analysis were derived for nickel, zinc, and lead. Overall, a suitably calibrated and evaluated portable XRF shows promise in making high-throughput assessments at population scales.
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Affiliation(s)
- Mayuri Bhatia
- Department of Civil Engineering, Indian Institute of Technology (IIT) Hyderabad, Kandi, TS 502285, India
| | - Aaron J. Specht
- Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA 02115, USA
- School of Health Sciences, Purdue University, West Lafayette, IN 47906, USA
| | - Vallabhuni Ramya
- Department of Civil Engineering, Indian Institute of Technology (IIT) Hyderabad, Kandi, TS 502285, India
| | - Dahy Sulaiman
- Department of Civil Engineering, Indian Institute of Technology (IIT) Hyderabad, Kandi, TS 502285, India
| | - Manasa Konda
- Department of Civil Engineering, Indian Institute of Technology (IIT) Hyderabad, Kandi, TS 502285, India
| | - Prentiss Balcom
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Elsie M. Sunderland
- Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA 02115, USA
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Asif Qureshi
- Department of Civil Engineering, Indian Institute of Technology (IIT) Hyderabad, Kandi, TS 502285, India
- Department of Climate Change, Indian Institute of Technology (IIT) Hyderabad, Kandi, TS 502285, India
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Gherase MR, Serna B, Kroeker S. A novel calibration for L-shell x-ray fluorescence measurements of bone lead concentration using the strontium K β/K αratio. Physiol Meas 2021; 42:10.1088/1361-6579/abf886. [PMID: 33857933 PMCID: PMC8177726 DOI: 10.1088/1361-6579/abf886] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/15/2021] [Indexed: 11/11/2022]
Abstract
Objective. Lead (Pb) is a well-known toxic element.In vivobone Pb concentration measurement is a long-term exposure metric complementary to blood Pb concentration measurement which is a metric of recent exposure.In vivohuman tibia bone Pb measurements using Pb K-shell or L-shell x-ray fluorescence (KXRF or LXRF) emissions were developed in the 1980s. KXRF bone Pb measurements using Cd-109 gamma rays and coherent-to-fluorescence ratio to account for differences between phantom andin vivomeasurements, was employed in human studies. Bone Pb LXRF method employed x-ray tubes. However, calibration procedures using ultrasound measurements of the soft tissue thickness (STT) proved inaccurate.Approach. In this study, bone and soft tissue (ST) phantoms simulatedin vivobone Pb measurements. Seven plaster-of-Paris cylindrical bone phantoms containing 1.01 mg g-1of strontium (Sr) were doped with Pb in 0, 8, 16, 29, 44, 59, and 74 μg g-1concentrations. Polyoxymethylene (POM), resin, and wax were each used to fabricate four ST phantoms in the approximate 1-4 mm thickness range. Pb LXRF measurements were performed using a previously developed optimal grazing incidence position method.Main results. Linear attenuation coefficients measurements of ST materials indicated that POM and resin mimicked well attenuation of Pb x-rays in skin and adipose tissue, respectively. POM and resin data indicated a bone Pb detection limit of 20 μg g-1for a 2 mm STT. Derived relationships between the Pb concentration, Pb LXRF and Sr Kβ/Kαratio data did not require STT knowledge. Applied to POM and resin data, the new calibration method yielded unbiased results.Significance.In vivobone Pb measurements in children were suggested following considerations of radiation dose, STT, detectability and distribution of Pb and Sr in bone. This research meets with the concerns regarding the negative effects of low levels of Pb exposure on neurodevelopment of children.
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Affiliation(s)
- Mihai R Gherase
- Department of Physics, California State University, Fresno, Fresno, CA, United States of America
| | - Blaz Serna
- Department of Physics, California State University, Fresno, Fresno, CA, United States of America
| | - Sarah Kroeker
- Department of Physics, California State University, Fresno, Fresno, CA, United States of America
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Specht AJ, Obrycki JF, Mazumdar M, Weisskopf MG. Feasibility of Lead Exposure Assessment in Blood Spots using Energy-Dispersive X-ray Fluorescence. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:5050-5055. [PMID: 33759507 PMCID: PMC10615324 DOI: 10.1021/acs.est.0c06622] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Collecting blood spots from newborns is a common procedure used to diagnose multiple health conditions. Fingerstick blood samples are routinely collected from children to diagnose elevated blood lead levels. In our study, we wanted to test the feasibility of using a high-power energy-dispersive X-ray fluorescence (EDXRF) device to accurately measure the concentration of lead in blood spots. We created spotted standards of a known concentration of lead on a filter paper at different volumes and concentrations. We determined the detection limit for lead through repeated measurements of our standards and calibration line slopes. We also tested the variability of the measured lead concentration across procedures and spotted blood volumes and found no significant additions to uncertainty in measurements. Finally, we compared blood lead concentrations measured by EDXRF and atomic absorption spectroscopy (AAS) and found EDXRF to be a significant predictor of blood lead (n = 22, R = 0.98, p value <0.001) with an average detection limit of 1.7 μg/dL of blood lead. This detection limit is similar to that of the AAS technique, which is commonly used in clinical testing laboratories for blood lead surveillance. These findings provide a proof of concept that blood spots measured by EDXRF may be used as a surveillance tool for lead exposure, even at elevated blood lead levels of 2-3 μg/dL.
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Affiliation(s)
| | - John F. Obrycki
- Department of Neurology, Boston Children’s Hospital, Boston, MA
| | - Maitreyi Mazumdar
- Harvard T.H. Chan School of Public Health, Boston, MA
- Department of Neurology, Boston Children’s Hospital, Boston, MA
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Fleming DEB, Crook SL, Evans CT, Nader MN, Atia M, Hicks JMT, Sweeney E, McFarlane CR, Kim JS, Keltie E, Adisesh A. Portable X-ray fluorescence of zinc applied to human toenail clippings. J Trace Elem Med Biol 2020; 62:126603. [PMID: 32623095 DOI: 10.1016/j.jtemb.2020.126603] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 04/28/2020] [Accepted: 06/25/2020] [Indexed: 11/29/2022]
Abstract
Zinc is an essential trace element in humans. Zinc deficiency can result in a range of serious medical conditions which include effects on growth and development, the immune system, the central nervous system, and the gastrointestinal system. Diagnosis of zinc deficiency is often precluded by the lack of a noninvasive and reliable biomarker. Zinc concentration in nail is considered an emerging biomarker of zinc status in humans. Whether zinc in nail accurately reflects zinc status is beyond the scope of the current study, but is an important research question. The development of a portable method to quickly assess zinc concentration from a single nail clipping could be a useful advance. In this study, single toenail clippings from 60 individuals living in Atlantic Canada were measured for zinc using a portable X-ray fluorescence (XRF) technique. These samples were obtained from the Atlantic PATH cohort, part of the largest chronic disease study ever performed in Canada. Each toenail clipping was measured using three 300 s trials with a mono-energetic portable XRF system. Results were then assessed using two different approaches to the XRF analysis: (1) factory-calibrated zinc concentrations were output from each trial, and (2) energy spectra were analyzed for the characteristic X-rays resulting from zinc. Following the measurement of zinc using the non-destructive portable XRF method, the same clippings were measured for zinc concentration using the "gold standard" technique of inductively coupled plasma-mass spectrometry (ICP-MS). A linear equation of best fit was determined for the relationship between average XRF output zinc concentration and ICP-MS zinc concentration, with a correlation coefficient r = 0.60. Similarly, a linear equation of best fit was found for the relationship between a normalized XRF energy spectrum zinc signal and ICP-MS zinc concentration, with a correlation coefficient r = 0.68. Individual ICP-MS zinc concentrations ranged from 32 μg/g to 140 μg/g, with a population average of 85 μg/g. The results of this study indicate that portable XRF is a sensitive method for the measurement of zinc in a single nail clipping, and provides a reasonable estimation of zinc concentration. Further method development is required before portable XRF be considered a routine alternative to ICP-MS for the assessment of zinc in nail clippings.
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Affiliation(s)
- David E B Fleming
- Physics Department, Mount Allison University, Sackville, New Brunswick, Canada.
| | - Samantha L Crook
- Physics Department, Mount Allison University, Sackville, New Brunswick, Canada
| | - Colby T Evans
- Physics Department, Mount Allison University, Sackville, New Brunswick, Canada
| | - Michel N Nader
- Physics Department, Mount Allison University, Sackville, New Brunswick, Canada
| | - Manuel Atia
- Medical Sciences, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Jason M T Hicks
- Atlantic PATH, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Ellen Sweeney
- Atlantic PATH, Dalhousie University, Halifax, Nova Scotia, Canada
| | | | - Jong Sung Kim
- Community Health and Epidemiology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Erin Keltie
- Community Health and Epidemiology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Anil Adisesh
- Atlantic PATH, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Medicine, Division of Occupational Medicine, University of Toronto, Toronto, Ontario, Canada; Faculty of Business, University of New Brunswick, Saint John, New Brunswick, Canada
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Nader MN, Fleming DEB. Assessment of alternative methods for analyzing X-ray fluorescence spectra. Appl Radiat Isot 2019; 146:133-138. [PMID: 30771728 DOI: 10.1016/j.apradiso.2019.01.033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 01/31/2019] [Accepted: 01/31/2019] [Indexed: 11/28/2022]
Abstract
When analyzing characteristic peaks in X-ray fluorescence (XRF) spectra, the peak area is the value most often used to quantify peak size. However, some studies have reported the amplitude of the peak instead of the area. When the width of the peak is allowed to vary from trial to trial in order to provide the best possible fit to the data, these two alternative methods can yield slightly different results. In the current study, these two approaches to peak analysis are compared for data obtained from bone reference materials having certified lead concentrations of 1.09 ± 0.03 μg/g, 16.1 ± 0.3 μg/g, 13.2 ± 0.3 μg/g, and 31.5 ± 0.7 μg/g. Measurements were made with an Olympus Innov-X Delta Premium portable XRF system. Using both the area and amplitude methods, lines of best fit were constructed for the lead Lα and lead Lβ signals as a function of lead concentration. Additionally, coefficients of variation were calculated for each reference material and condition of analysis. To assess possible variations over time, the procedure was performed at two points separated by about one year. The amplitude and area methods were found to produce results which were consistent and proportional. Using either method, lead XRF signal plotted as a function of known lead concentration produced adjusted r2 values of ∼0.99. The amplitude method provided slightly higher adjusted r2 values overall. Coefficients of variation were generally very similar between the two methods, although more pronounced differences emerged from measurements of the lowest concentration reference material.
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Affiliation(s)
- Michel N Nader
- Physics Department, Mount Allison University, 67 York Street, Sackville, New Brunswick, Canada
| | - David E B Fleming
- Physics Department, Mount Allison University, 67 York Street, Sackville, New Brunswick, Canada.
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Fleming DEB, Crook SL, Evans CT. Assessing zinc from a nail clipping using mono-energetic portable X-ray fluorescence. Appl Radiat Isot 2019; 145:170-175. [PMID: 30639633 DOI: 10.1016/j.apradiso.2018.12.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 12/19/2018] [Accepted: 12/29/2018] [Indexed: 02/05/2023]
Abstract
A mono-energetic X-ray beam from a portable X-ray fluorescence device was used to excite characteristic X-rays from zinc in a series of nail clipping phantoms. Twenty nail clipping phantoms having equal zinc concentrations of ~40 µg/g, but with different physical characteristics, were measured individually for 300 s using a small diameter (~1 mm) X-ray beam. Energy spectra obtained from the measurements were analyzed using PyMca software. Zinc signal size varied widely between the different clippings, with a relative standard deviation of 41% observed in the combined signal from zinc Kα and Kβ characteristic X-rays. Three different normalization approaches were introduced to account for variation in the amounts of sample interrogated by the X-ray beam. All three approaches produced similar results, and successfully reduced the relative standard deviation to between 12% and 13%. A clear trend was still observed, however, between the normalized zinc signal and the thickness of clipping measured. To account for this effect, normalized signals were adjusted to calculate "thickness-corrected" values. The relative standard deviation of these thickness-corrected values was 6.2%. Reproducibility of measurement from individual clippings was excellent, with relative standard deviations on the order of 1%, with or without normalization. Overall, this new method of measuring zinc in nail shows promise for the assessment of zinc status in humans using a portable device. The method is sensitive, rapid, and requires only a single nail clipping.
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Affiliation(s)
- David E B Fleming
- Physics Department, Mount Allison University, Sackville, NB, Canada.
| | - Samantha L Crook
- Physics Department, Mount Allison University, Sackville, NB, Canada
| | - Colby T Evans
- Physics Department, Mount Allison University, Sackville, NB, Canada
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Fleming DEB, Bennett SR, Frederickson CJ. Feasibility of measuring zinc in human nails using portable x-ray fluorescence. J Trace Elem Med Biol 2018; 50:609-614. [PMID: 29728300 DOI: 10.1016/j.jtemb.2018.04.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 03/24/2018] [Accepted: 04/20/2018] [Indexed: 10/17/2022]
Abstract
A variety of adverse health effects have been identified as resulting from zinc deficiency. Zinc supplementation may therefore be indicated for certain individuals or populations. A rapid and straightforward means of assessing zinc status in humans would be of considerable medical benefit. In this study, the feasibility of measuring zinc levels in human fingernails or toenails using a portable x-ray fluorescence technique was assessed. Whole nail models (or phantoms) were constructed from resin, and dosed with various concentrations of zinc. These different concentration "nails" were cut into small slices of 4.4 ± 0.2 mm width. The combination of these various slices into different arrangements allowed the modeling of different time-dependent zinc exposure scenarios. A portable x-ray fluorescence device was tested using an "open beam" configuration having a beam diameter of ∼9 mm, and using a "weld mask" configuration with the beam width reduced to 2.9 mm. Minimum detection limits were determined to be 0.15 ± 0.01 ppm for the open beam, and 1.13 ± 0.08 ppm when using the weld mask. By scanning across the length of the model nails, it was demonstrated that differences in zinc levels deposited over time could be detected, and that the weld mask configuration was better suited to resolving spatial changes. The x-ray fluorescence approach was found to be highly sensitive for detecting zinc in nail, and capable of differentiating patterns of zinc uptake over time.
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Specht AJ, Kponee K, Nkpaa KW, Balcom PH, Weuve J, Nie LH, Weisskopf MG. Validation of x-ray fluorescence measurements of metals in toenail clippings against inductively coupled plasma mass spectrometry in a Nigerian population<sup/>. Physiol Meas 2018; 39:085007. [PMID: 30091720 DOI: 10.1088/1361-6579/aad947] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Metal exposures have been linked with many adverse health outcomes affecting nearly every system in the body. Exposure to metals has been tracked primarily using blood. Blood metal concentrations have drawbacks as biomarkers stemming from the metals' short biologic half-lives, shipping and storage requirements, and invasive collection procedures. Toenails, which capture a longer exposure period, can be collected non-invasively and stored at room temperature, and can be more feasible and cost-effective for large-scale population studies. APPROACH Inductively coupled plasma mass spectrometry (ICP-MS) has been used for analysis of toenail metal concentrations, but x-ray fluorescence (XRF) has many advantages in versatility and cost effectiveness over these analyses. This study compared toenail concentrations of manganese (Mn) and lead (Pb) measured with XRF against ICP-MS, in samples collected from 20 adults in Nigeria. To do this we developed a novel calibration method that corrects XRF measurements for toenail weight and thickness to reduce the variability in XRF measurements of toenail clippings. MAIN RESULTS We found a high correlation (R = 0.91) between toenail manganese metal measurements made with XRF and ICP-MS and a correlation of (R = 0.32) between toenail lead XRF and ICP-MS with over half of the lead results below the detection limit of the instrumentation. SIGNIFICANCE XRF can be used effectively to quantify metals at the part per million level or lower depending on the XRF equipment used in the measurements.
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Affiliation(s)
- Aaron J Specht
- Harvard T.H. Chan School of Public Health, Boston, MA, United States of America. Author to whom any correspondence should be addressed
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Zhang X, Specht AJ, Weisskopf MG, Weuve J, Nie LH. Quantification of manganese and mercury in toenail in vivo using portable X-ray fluorescence (XRF). Biomarkers 2017; 23:154-160. [PMID: 28901783 DOI: 10.1080/1354750x.2017.1380082] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND AND OBJECTIVE Toenail is an advantageous biomarker to assess exposure to metals such as manganese and mercury. Toenail Mn and Hg are in general analyzed by chemical methods such as inductively coupled plasma mass spectrometry and atomic absorption spectrophotometry. In this project, a practical and convenient technology-portable X-ray florescence (XRF)-is studied for the noninvasive in vivo quantification of manganese and mercury in toenail. MATERIAL AND METHODS The portable XRF method has advantages in that it does not require toenail clipping and it can be done in 3 min, which will greatly benefit human studies involving the assessment of manganese and mercury exposures. This study mainly focused on the methodology development and validation which includes spectral analysis, system calibration, the effect of toenail thickness, and the detection limit of the system. Manganese- and mercury-doped toenail phantoms were made. Calibration lines were established for these measurements. RESULTS The results show that the detection limit for manganese is 3.65 μg/g (ppm) and for mercury is 0.55 μg/g (ppm) using 1 mm thick nail phantoms with 10 mm soft tissue underneath. DISCUSSION AND CONCLUSION We conclude that portable XRF is a valuable and sensitive technology to quantify toenail manganese and mercury in vivo.
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Affiliation(s)
- Xinxin Zhang
- a School of Health Sciences , Purdue University , West Lafayette , IN , USA
| | - Aaron J Specht
- b Department of Environmental Health , Harvard T.H. Chan School of Public Health , Boston , MA , USA
| | - Marc G Weisskopf
- b Department of Environmental Health , Harvard T.H. Chan School of Public Health , Boston , MA , USA
| | - Jennifer Weuve
- c Department of Epidemiology , Boston University School of Public Health , Boston , MA , USA
| | - Linda H Nie
- a School of Health Sciences , Purdue University , West Lafayette , IN , USA
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