Human Nail Clippings Research Articles

New Formulation-Microporation Combination Approaches to Delivering Ciclopirox across Human Nails.

Topical treatments for onychomycosis are of interest to those seeking to avoid systemic drug interactions and to improve systemic safety. This work aimed to develop aqueous-based, simple, and cost-effective vehicles that provide high solubility for ciclopirox and enable the delivery of an active through channels created by nail microporation. Following solubility tests, aqueous gels and thermogels based on hydroxypropylmethylcellulose and poloxamer 407, respectively, were loaded with 8% and 16% ciclopirox. Their performance was then compared to the marketed lacquer Micolamina® in in vitro release tests with artificial membranes and in in vitro permeation tests with human nail clippings with and without poration. Finally, a microbiological assay compared the best gel formulations and the reference product. Little correlation was observed between the in vitro release and the permeation data, and the drug release was highly membrane-dependent. Ciclopirox nail retention in single-dose, porated nails tests was larger than in daily-dosing, non-porated nail conditions. The series of new gel and thermogel vehicles delivered ciclopirox more effectively than Micolamina® in single-dose, porated nail experiments. The inhibition of Trichophyton rubrum activity was significantly increased with microporated nails when the gel formulations were applied but not with Micolamina®. Overall, the results suggest that the new vehicles could be successfully combined with nail microporation to improve the drug delivery and efficacy of topical antifungal medication while reducing the dosing frequency, facilitating patients' adherence.

Detection of 3-4 Methylenedioxyamphetamine from Drug Abuser’s Fingers and Toenails using Liquid Chromatography with Mass Spectroscopy

information regarding drug abuse and pharmaceutical use. In recent years, drug analysis in human nail clippings has proven its significant value in forensic toxicological applications, identification of in utero drug exposure, monitoring of drug treatment programmes, and therapeutic drug monitoring. Nails have various advantages over conventional matrices (blood and urine), which include a longer detection window (months to years), non-invasive sample collection, and easy storage and transportation. These aspects make nails a very significant matrix for forensic toxicology and therapeutic drug monitoring. Because of the low concentrations of drugs of abuse and pharmaceuticals present in nails and the complexity of the keratinized matrix, analytical techniques need to be more sensitive, and sample preparation is crucial. The aim of the present study is to develop a simple, high-performance liquid chromatography-mass spectroscopy (LC-MS) method for the identification and quantitation of 3,4-methylenedioxyamphetamine (MDA) in fingernail and toenail clippings. Finger and toenail clippings were collected from six users undergoing treatment at a rehab center in Ujjain, M.P., India. Nail clippings were initially decontaminated, then hydrolyzed in 1 M NaOH at 370°C, extracted with ethyl acetate, diluted with methanol, and then subjected to LC-MS analysis. The calibration curve was constructed over the 0.5 to 30 ng/mL concentration range using the MDA reference standard. The limit of detection was calculated at 1.10 ng/mL and the limit of quantification was recorded at 3.67 ng/mL in standard solutions, whereas the respective values in spiked nail clippings were 1.21 and 4.6 ng/mg. The developed method has obtained significant results in original nail clippings with mean concentration ranges of 0.12 ng/mg in fingernails and 0.08 ng/mg in toenails in six abuser samples. The new method developed has been found to be capable of detecting the 3,4-methylendioxyamphetamine MDA drug in nail clippings even after 90 days of drug intake.

Testing for clomiphene in keratinous matrices (hair and nail).

Clomiphene or clomifene is a selective estrogen receptor modulator (SERM), used to treat female fertility in case of ovulatory dysfunction. In sport, clomiphene is prohibited at all times for use by athletes and is listed in the section S4.2 (hormone and metabolic modulators) by the World Anti-Doping Agency (WADA). Indeed, clomiphene can indirectly increase testosterone levels in the body and can mitigate some side effects of synthetic steroid abuse. Despite its prescription to millions of subjects, its detection in human hair or nail clippings has never been reported. The aim of this study was to develop a specific method to identify clomiphene in hair and nail clippings by LC-MS-MS. The procedure was then applied in a case of challenged doping results. The method involves sonication/incubation for 1 hour of 30 mg of pulverized material in 1 mL of methanol in presence of 2 ng diazepam-d5 used as internal standard. The chromatographic separation was performed using a HSS C18 column with a 15 min gradient elution. After spiking blank hair and nail with the corresponding amounts of clomiphene, linearity was verified from 1 to 500 pg/mg (r² = 0.9994 and 0.9995 for hair and nail, respectively). The limit of detection was estimated at 0.3 pg/mg for both matrices. No interference was noted from endogenous compounds, particularly steroids. Clomiphene was identified at 85 and 20 pg/mg in the pubic hair and the fingernail clippings, respectively, of a male athlete challenging an adverse analytical finding.

Production of keratinous waste degrading enzyme by Arthroderma multifidum isolated from soil of Rajasthan, India

The aim of this study was to detect and evaluate the extracellular keratinase enzyme production by Arthroderma multifidum TKKASa (KU560574), a keratin-degrading fungus isolated from the keratin contaminated soil of Rajasthan, India. This study focused on the evaluation of the effect of keratin substrates, pH, incubation days, temperature and metal ions for keratinase enzyme production. The highest enzyme production by A. multifidum was observed on chicken feathers (56.25±0.69 U/mL) followed by human hair, animal hair and human nail clippings. The maximum keratinase production by A. multifidum was achieved at 40˚C with 58.80±0.98 U/mL enzyme activity and pH 8.0 (56.65±0.85 U/mL) after 12 days of fermentation. The addition of metal ions in basal salt media resulted in the decrease in enzyme production. This study reports keratinase production by A. multifidum and the high efficiency on the chicken feather degradation in comparison to human nail clipping, animal hair and human hair degradation. Its potential use is in biotechnological processes such as biodegradation of keratin wastes, eco-friendly dehairing and poultry feed production.

A drug-in-adhesive anti-onychomycotic nail patch: Influence of drug and adhesive nature on drug release, ungual permeation, in vivo residence in human and anti-fungal efficacy

A nail patch is an attractive option for the topical treatment of onychomycosis, although no product is commercially available. We previously identified optimal nail patch formulations for two anti-onychomycotic drugs, based on their properties, as well as those of the other patch components. In this paper, our aim was to further investigate the potential of the patch formulations as topical nail medicines, in particular, whether the drug-in-adhesive patches release drug which then permeates into and through the nail plate and show anti-fungal efficacy, and whether and to what extent they remain adhered to the human nail plate in vivo when tested over 2 week durations. In addition, the influence of the drug (amorolfine HCl, ciclopirox olamine) and PSA (Duro-Tak 2852 or Duro-Tak 202A) on these parameters was determined. We found that both the nature of the drug and of the PSA influenced in vitro drug release. The nature of the drug, but not that of the PSA, influenced ungual drug permeation through human nail clippings, with considerably greater (almost double) permeation for ciclopirox olamine, the smaller and less lipophilic molecule. In vivo residence, tested with 3 out of the 4 patches, excluding the patch where ciclopirox olamine degraded with time, showed greater residence on toenails compared to fingernails reflecting their far lesser exposure to environmental stresses during daily activities. In vivo residence was enhanced when the patch was cut to the shape of the nail, was applied at bedtime, and when a clear colourless nail varnish was applied on top of the patch to ‘seal’ it into place on the nail. Comparison of the patches indicated greater residence of Duro-Tak 202A containing patches over those containing Duro-Tak 2852. Amorolfine HCl in Duro-Tak 202A based patch also showed antifungal efficacy in contrast to Duro-Tak 2852-based patch, and is particularly promising for further development as a potential toenail medicine, remaining almost fully adhered to toenails for at least two weeks.

The measurement of trace elements in human nails and nail clippings using portable X‐ray fluorescence: A review

A variety of biomarkers are available for the assessment of human exposure to, and absorption of, trace elements. The measurement of trace elements in nail or nail clippings offers some benefits relative to other body sites. Typically, concentrations of elements are assessed in clippings, using high precision methods such as inductively coupled plasma mass spectrometry or instrumental neutron activation analysis. Over the last decade, portable X‐ray fluorescence (pXRF) has emerged as a novel method with potential advantages for the measurement of trace elements in nail and nail clippings. This review paper examines early developments and recent work in the use of pXRF to measure elements such as As, Se, Mn, Zn, Cr, Pb, and Hg in nails and nail clippings. While initial pXRF studies were limited to the use of nail phantoms and nail clipping phantoms, more recent work has applied the pXRF method with real nail clippings and nails. Results have been promising, but a number of issues have emerged requiring additional attention. These relate to the analysis of X‐ray spectra, selection of X‐ray beam for excitation, method validation and normalization, and practical aspects of study design. With consideration of these issues, pXRF offers significant potential to provide a straightforward, economical, and rapid measurement approach to help improve our understanding of trace element exposure and related health outcomes.

Potential of Naftifine Application for Transungual Delivery.

Naftifine is used to treat fungal skin infections as it inhibits dermatophytes, which are the cause of onychomycosis. However, naftifine’s ability to permeate the human nail barrier has not been investigated, thus, the antimycotic potential is not clearly established. This work aims to evaluate the effect of penetration enhancing factors on the accumulation of naftifine hydrochloride through human nail clippings. Naftifine polymeric nail lacquers with Eudragit RL100 were developed as a suitable delivery system. Low penetration of naftifine into nail has been determined as less than 10% of applied drug dose accumulated in the nail layers. Incorporation of thioglycolic acid into formulations resulted in increased accumulation of antifungal agent in the nail layers by 100% compared with a control group. Salicylic acid did not effect naftifine accumulation in the human nail. The permeation of naftifine through the nail increased by threefold when the thioglycolic acid-containing formulation was applied and the nail was pretreated with a fractional CO2 laser. Structural changes of the nail barrier, induced by fractional CO2 laser, were visualized by microscopy. The results suggest, that naftifine nail penetration could be significantly increased when physical and chemical enhancing factors are applied.

Assessment of Bombax ceiba Leaves Extract and Pleurotus ostreatus Fungus Filtrate on treatment of some Isolated Dermatophytic Fungi

This study was conducted in the microbiology laboratory of the ecology department, faculty of science, in order to evaluate the effect of Bombax ceiba leaves extract and Pleurotus ostreatus fungi filterate to treat some of dermatophytic fungi. A bout 50 samples of infectious fungi were collected for isolation. The samples that isolated from skin scraps, human nail clippings, and the fingers were diagnosed as Aspergillus fumigantus which was (41.57%) followed by Aspergillus niger of (37.36%) while other isolated fungi represented 22% on (SDA) medium. The results showed that the epidermis is the most infected by the fungus which reached (54%) in compared with the rest of the body, also the results indicated that the percentage of infection of males was more than females which was 64%The results also, showed that the tested samples on SDA medium, were highly sensitive (100%) to the extract of bombax ceiba leaves in compared with the other antimicrobial artificial agents (Griseofulvin, Miconazole, Nystatin, ketoconazole. wheras the inhibition diameters for studied fungi were 2.5 mm,2mm.1mm and 0 mm, respectively, While the inhibitory effect of the Pleurotus ostreatus fungus filterate was found to be less than susceptibility from the bombax leaves extract which was 75% of petridish area.

Potential of Chemical and Physical Enhancers for Transungual Delivery of Amorolfine Hydrochloride.

Topical monotherapy of nail infection is limited by poor drug permeability into the human nail plate. Numerous substances and methods are applied to improve the antifungal agent delivery across the nail plate. This work aimed to evaluate the effect of chemical and physical enhancers on the accumulation and permeation of amorolfine hydrochloride through human nail clippings. Polymeric nail lacquers with Eudragit E100 were developed as a potentially suitable delivery system for amorolfine hydrochloride. Incorporating thioglycolic acid and urea into formulations provided increased accumulation of antifungal agent in nail layers of up to 100% and 57%, respectively. Structural changes of nail barrier, induced by fractional CO2 laser, were visualized by microscopy. The permeation of amorolfine hydrochloride through the nail increased twofold when thioglycolic acid-containing formulation was applied and the nail was pretreated with a fractional CO2 laser. The results suggest that this novel combination of enhancers has the potential to be an effective option for topical drug delivery through the nail, and increased the efficacy of treatment.

Enhancement of tioconazole ungual delivery: Combining nanocapsule formulation and nail poration approaches

This work investigated the impact of formulation including in vitro release profile, repeated dosing, and nail poration on the ex vivo nail delivery performance of antifungal formulations. Chitosan coated and uncoated tioconazole-loaded nanocapsules and a nano-based film-forming vehicle were assessed via in vitro release and in vitro permeation tests using an artificial membrane and human nail clippings, respectively. The later involved single and daily dosing experiments with intact and porated nails. Additional experiments with Nile Red-loaded formulations evaluated the depth of penetration of the fluorescent marker into the nail by laser scanning confocal microscopy. The nanocapsule formulations prolonged release of tioconazole for longer than the control solutions and this ability was related to an enhanced nail penetration of the drug. Further, the new film-forming formulation delivered its drug payload more efficiently than a marketed product. Daily dosing of the formulations doubled the amount of drug recovered from the nails. Porating the nails enhanced tioconazole delivery in single dose experiments only. The depth of penetration of Nile Red into the nails clippings ranged between 90–160 μm. This research suggests that ensuring prolonged release of a drug is fundamental to develop efficacious topical nail formulations.

Chrysosporium queenslandicum: a potent keratinophilic fungus for keratinous waste degradation

PurposeKeratinous wastes are the solid environmental pollutant generated from poultry farms, slaughterhouses and barber’s shops. The aim of the present study is the degradation of keratinous wastes in an eco-friendly way by biological methods, which should further be helpful to reduce the wastes and recycled into valuable feed and fertilizers.MethodsDegradation of keratinous substrates was assessed by highly potent keratinophilic fungi, namely Chrysosporium queenslandicum TKKASb Apinis and R.G. Rees. This chicken feather degrading fungal strain previously isolated and identified by morphological and 18 s rDNA sequencing in laboratory, was used in the present study. Ch. queenslandicum was inoculated into the basal salt medium (BSM) with keratinous substrates for 12 and 24 days at 28 ± 2 °C to observe degradation. The rate of degradation was expressed as weight loss of keratin substrate over incubation days and pH variation.ResultsIn this study, Ch. queenslandicum showed maximum degradation on chicken feathers followed by human nail clippings, animal hair and human hair. The degradation rate on chicken feather was 38.40 ± 0.80 and 46.40 ± 2.50% after 12 and 24 days, respectively. The basal salt medium’s pH was increased over incubation time. Scanning electron microscopy (SEM) examination also demonstrated the degradation of chicken feathers.ConclusionsThe results suggest that Ch. queenslandicum possess the potential biotechnological applications which can be used in the hydrolysis of keratinous waste and recycling of poultry waste for environmental protection. The hydrolyzed keratinous material can also be utilized as the source of fertilizers for plants and feed for animals.

Portable x-ray fluorescence for the analysis of chromium in nail and nail clippings

Assessment of chromium content in human nail or nail clippings could serve as an effective biomarker of chromium status. The feasibility of a new portable x-ray fluorescence (XRF) approach to chromium measurement was investigated through analysis of nail and nail clipping phantoms. Five measurements of 180s (real time) duration were first performed on six whole nail phantoms having chromium concentrations of 0, 2, 5, 10, 15, and 20µg/g. Using nail clippers, these phantoms were then converted to nail clippings, and assembled into different mass groups of 20, 40, 60, 80, and 100mg for additional measurements. The amplitude of the chromium Kα characteristic x-ray energy peak was examined as a function of phantom concentration for all measurement conditions to create a series of calibration lines. The minimum detection limit (MDL) for chromium was also calculated for each case. The chromium MDL determined from the whole nail intact phantoms was 0.88±0.03µg/g. For the clipping phantoms, the MDL ranged from 1.2 to 3.3µg/g, depending on the mass group analyzed. For the 40mg clipping group, the MDL was 1.2±0.1µg/g, and higher mass collections did not improve upon this result. This MDL is comparable to chromium concentration levels seen in various studies involving human nail clippings. Further improvements to the portable XRF technique would be required to detect chromium levels expected from the lower end of a typical population.

Development of ciclopirox nail lacquer with enhanced permeation and retention.

Onychomycosis is a prevailing disease caused by fungal infection of nails that mostly affects athletes and the elderly. Ciclopirox is approved by the US Food and Drug Administration for the topical treatment of onychomycosis. However, the desired penetration of ciclopirox into the nail bed has not been achieved via topical application for efficient treatment. Therefore, the main aim of this study was to enhance ciclopirox permeation and retention in nail by the development of a new nail lacquer formulation. We screened the effects of different solvents, alkalizing agents, and permeation enhancers on the permeation of bovine hooves by ciclopirox and its retention in human nail clippings. The results suggest that isopropyl alcohol, potassium hydroxide, and urea as the solvent, alkalizing agent, and permeation enhancer, respectively, improved the permeation of the ciclopirox nail lacquer formulation the most with high flux rates. Comparison of the final formulation and marketed product revealed enhanced retention of ciclopirox from our developed formulation in human nail clippings. Therefore, our newly developed nail lacquer may be a potentially effective formulation for the treatment of onychomycosis in humans.

Human Nail Clippings as a Source of DNA for Genetic Studies.

Blood samples have traditionally been used as the main source of DNA for genetic analysis. However, this source can be difficult in terms of collection, transportation, and long-term storage. In this study, we investigated whether human nail clippings could be used as a source of DNA for SNP genotyping, null-allele detection, and whole-genome amplification. From extracted nail DNA, we achieved amplicons up to a length of ~400 bp and >96% concordance for SNP genotyping and 100% concordance for null-allele detection compared to DNA derived from matched blood samples. For whole-genome amplification, OmniPlex performed better than Multiple Displacement Amplification with a success rate of 89.3% and 76.8% for SNP genotyping and null-allele detection, respectively. Concordance was ~98% for both methods. When combined with OmniPlex whole-genome amplification, human nail clippings could potentially be used as an alternative to whole blood as a less invasive and more convenient source of DNA for genotyping studies.

Development and validation of an ex vivo electron paramagnetic resonance fingernail biodosimetric method.

There is an imperative need to develop methods that can rapidly and accurately determine individual exposure to radiation for screening (triage) populations and guiding medical treatment in an emergency response to a large-scale radiological/nuclear event. To this end, a number of methods that rely on dose-dependent chemical and/or physical alterations in biomaterials or biological responses are in various stages of development. One such method, ex vivo electron paramagnetic resonance (EPR) nail dosimetry using human nail clippings, is a physical biodosimetry technique that takes advantage of a stable radiation-induced signal (RIS) in the keratin matrix of fingernails and toenails. This dosimetry method has the advantages of ubiquitous availability of the dosimetric material, easy and non-invasive sampling, and the potential for immediate and rapid dose assessment. The major challenge for ex vivo EPR nail dosimetry is the overlap of mechanically induced signals and the RIS. The difficulties of analysing the mixed EPR spectra of a clipped irradiated nail were addressed in the work described here. The following key factors lead to successful spectral analysis and dose assessment in ex vivo EPR nail dosimetry: (1) obtaining a thorough understanding of the chemical nature, the decay behaviour, and the microwave power dependence of the EPR signals, as well as the influence of variation in temperature, humidity, water content, and O₂ level; (2) control of the variability among individual samples to achieve consistent shape and kinetics of the EPR spectra; (3) use of correlations between the multiple spectral components; and (4) use of optimised modelling and fitting of the EPR spectra to improve the accuracy and precision of the dose estimates derived from the nail spectra. In the work described here, two large clipped nail datasets were used to test the procedures and the spectral fitting model of the results obtained with it. A 15-donor nail set with 90 nail samples from 15 donors was used to validate the sample handling and spectral analysis methods that have been developed but without the interference of a native background signal. Good consistency has been obtained between the actual RIS and the estimated RIS computed from spectral analysis. In addition to the success in RIS estimation, a linear dose response has also been achieved for all individuals in this study, where the radiation dose ranges from 0 to 6 Gy. A second 16-donor nail set with 96 nail samples was used to test the spectral fitting model where the background signal was included during the fitting of the clipped nail spectra data. Although the dose response for the estimated and actual RIS calculated in both donor nail sets was similar, there was an increased variability in the RIS values that was likely due to the variability in the background signal between donors. Although the current methods of sample handling and spectral analysis show good potential for estimating the RIS in the EPR spectra of nail clippings, there is a remaining degree of variability in the RIS estimate that needs to be addressed; this should be achieved by identifying and accounting for demographic sources of variability in the background nail signal and the composition of the nail matrix.

Synchrotron X-ray absorption spectroscopy analysis of arsenic chemical speciation in human nail clippings

Environmental context Chronic ingestion of arsenic leads to its accumulation in keratinous tissues, which can represent a risk factor for developing cancer. We use synchrotron X-ray absorption spectroscopy to investigate chemical bonding of arsenic in the keratins from nail clippings of volunteers from areas in Atlantic Canada with low-to-moderate arsenic contamination of drinking water. The study helps our understanding of arsenic metabolism and its role in cancer development. Abstract Drinking water aquifers in many areas of the world have naturally elevated levels of inorganic arsenic exceeding the World Health Organization limit. Arsenic concentrations in human nail clippings are commonly used as a biomarker of exposure to this toxic element. However, the chemical form of arsenic accumulated in nail tissues is not well determined. We employed synchrotron microprobe and bulk X-ray absorption spectroscopy techniques to analyse the concentration and chemical speciation of arsenic in the finger- and toenail clippings of volunteers living in the vicinity of Sackville, New Brunswick, Canada. This area is known to have low-to-moderately elevated levels of arsenic in ground water. Arsenic species in clippings were represented by three main groups, distinguished by the As-K near-edge X-ray absorption fine structure spectra: (1) AsIII type, which can be fitted as a mixture of As bound to thiols, and also to oxygen or methyl groups, with a small contribution from AsV species, (2) AsV type, best represented by fitting arsenate in aqueous solution and (3) The AsIII+AsV mixture type. The high proportion (%) of sulfur-bound arsenic species most likely corresponds to binding between arsenic (in its trivalent and, to a lesser extent, pentavalent forms) and cysteine residues in the sulfur-rich fraction of keratin and keratin-associated proteins. Further work is needed to explore whether these chemical species could be used as toxicity biomarkers of human exposure to elevated levels of As in drinking water.

X-ray fluorescence measurements of arsenic micro-distribution in human nail clippings using synchrotron radiation

Arsenic (As) distribution in nail clippings from three healthy human subjects was investigated using the microbeam experimental setup of the hard x-ray micro-analysis (HXMA) beamline from the Canadian Light Source (CLS) synchrotron. A pair of toenail and fingernail clippings was collected from each of three subjects (one contributed two fingernail clippings). The fingernail and toenail clippings were embedded in polyester resin and cut in cross-sectional slices with an average thickness of 270 µm. Nine nail clipping cross sections were analyzed from the three subjects. The same method was used to produce five cross sections of nail phantom clippings with concentrations of As ranging from 0 to 20 µg g−1, in increments of 5 µg g−1. These samples were used to produce a calibration line for the As Kα peak. The energy of the x-ray beam was set at 13 keV for optimal excitation of As and the beam size was 28 × 10 µm2. Each sample was analyzed using a point-by-point scanning technique in a 45° beam-sample and 90° beam-detector geometry. The dwelling time was set at 30 s for the human nail clippings and 20 s for the nail phantom clippings, using a step size of 50 µm in both the horizontal and vertical directions for all samples. As concentration for each point was calculated based on the calibration line parameters and the fitted amplitude of the observed As Kα peak. As concentration maps were produced for each nail clipping cross section. The maps show that small regions (<0.1 mm2) with higher As concentrations (>1 µg g−1) are located predominantly in the ventral and dorsal layers of the nail. The results are in agreement with findings reported in a recent study and can be linked to nail histology and keratin structure.

Calibrations for measurement of manganese and zinc in nail clippings using portable XRF

A calibration method was developed to assess elemental concentrations in nail clippings, using a portable X‐ray fluorescence (XRF) device. Specifically, manganese and zinc were investigated in this study. Two sets of phantom nail clipping samples were prepared, one set containing manganese and one set containing zinc. In both sets, elemental concentrations in the phantom clippings were varied from 10 to 50 µg/g, in increments of 10 µg/g. Additionally, for each concentration, five distinct masses of sample were prepared ranging from 20 to 100 mg, in increments of 20 mg. XRF spectrometry was performed with the various samples using a portable X‐ray tube and detector system.Kα characteristic X‐rays were detected for both manganese and zinc. Intensities of detection were plotted against added concentration, resulting in linear relationships for both manganese and zinc. The slopes of these calibration lines were then examined as a function of sample mass. An empirical function was fit to the slope–mass relationship and compared with those obtained previously from other elements. By using this XRF calibration approach, it is possible to estimate elemental concentrations in human nail clippings for a variety of elements of medical interest. Copyright © 2013 John Wiley &amp; Sons, Ltd.

A calibration method for proposed XRF measurements of arsenic and selenium in nail clippings

A calibration method for proposed x-ray fluorescence (XRF) measurements of arsenic and selenium in nail clippings is demonstrated. Phantom nail clippings were produced from a whole nail phantom (0.7 mm thickness, 25 × 25 mm2 area) and contained equal concentrations of arsenic and selenium ranging from 0 to 20 µg g−1 in increments of 5 µg g−1. The phantom nail clippings were then grouped in samples of five different masses: 20, 40, 60, 80 and 100 mg for each concentration. Experimental x-ray spectra were acquired for each of the sample masses using a portable x-ray tube and a detector unit. Calibration lines (XRF signal in a number of counts versus stoichiometric elemental concentration) were produced for each of the two elements. A semi-empirical relationship between the mass of the nail phantoms (m) and the slope of the calibration line (s) was determined separately for arsenic and selenium. Using this calibration method, one can estimate elemental concentrations and their uncertainties from the XRF spectra of human nail clippings.

Growth rate of human fingernails and toenails in healthy American young adults

Human nail clippings are increasingly used in epidemiological studies as biomarkers for assessing diet and environmental exposure to trace elements or other chemical compounds. However, little is known about the growth rate of human nails. To estimate the average growth rate of fingernails and toenails and examine factors that may influence nail growth rate. Twenty-two healthy American young adults marked their nails close to the proximal nail fold with a provided nail file following a standardized protocol, and recorded the date and the distance from the proximal nail fold to the mark. One to three months later, participants recorded the date and distance from the proximal nail fold to the mark again. Nail growth rate was calculated based on recorded distance and time between the two measurements. Average fingernail growth rate was faster than that of toenails (3.47 vs. 1.62 mm/month, P < 0.01). There was no significant difference between right and left fingernail/toenail growth rates. The little fingernail grew slower than other fingernails (P < 0.01); the great toenail grew faster than other toenails (P < 0.01). Younger age, male gender, and onychophagia were associated with faster nail growth rate; however, the differences were not statistically significant. Nail growth rates have increased compared with previous estimates conducted decades ago. Toenail clippings may reflect a long exposure time frame given the relatively slow growth rate.