Seasonal patterns in trace elements assessed in toenails

BACKGROUND

Seasonal patterns in measured exposure biomarkers can cause measurement error in epidemiological studies. There is little research about the seasonality of metals and trace elements when assessed in toenail samples. Adjusting for such patterns in models for estimating associations between long-term exposures and health outcomes can potentially improve precision and reduce bias.

OBJECTIVES

Assess and describe seasonal patterns in toenail measurements of trace elements.

METHODS

The Sister Study enrolled women residing in the US, including Puerto Rico, whose sister had been diagnosed with breast cancer. At the time of enrollment, participants removed nail polish and collected their toenail clippings, which were cleaned before analysis. We considered the following elements: iron, vanadium, aluminum, chromium, manganese, cobalt, nickel, copper, zinc, arsenic, selenium, molybdenum, cadmium, tin, antimony, mercury, and lead. For two subsamples of the cohort, we fit trigonometric regression models with toenail element measures as the outcome, using sine and cosine functions of the collection day (transformed to an angle) to capture seasonal patterns. These models can estimate the amplitude and timing of the peaks in measures. We evaluated the evidence for a seasonal effect by comparing for each measured element the trigonometric model to a model that was constant across time.

RESULTS

There was a seasonal trend in toenail element concentration for iron, aluminum, vanadium, chromium, manganese, cobalt, arsenic, molybdenum, cadmium, tin, and lead, all of which peaked near mid-August. Seasonal patterns were concordant across two non-overlapping samples of women, analyzed in different labs.

DISCUSSION

Given the evidence supporting seasonal patterns for 11 of the 17 elements measured in toenails, correcting for seasonality of toenail levels of those trace elements in models estimating the association between those exposures and health outcomes is important. The basis for higher concentrations in toenails collected during the summer remains unknown.

Healthcare Wearable Sensors Adhesion to Human Fingernails and Toenails

A novel adhesion method of a sensor to a fingernail is described. Wearable sensors can provide health insights to humans for a wide variety of benefits, such as continuous wellness monitoring and disease monitoring throughout a patient's daily life. While there are many locations to place these wearable sensors on the body, we will focus on the fingertip, one significant way that people interact with the world. Like artificial fingernails used for aesthetics, wearable healthcare sensors can be attached to the fingernail for short or long time periods with minimal irritation and disruption to daily life. In this study the structure and methods of healthcare sensors' attachment and removal have been explored to support (1) the sensor functional requirements, (2) biological and environmentally compatible solutions and (3) ease of attachment and removal for short- and long-term user applications. Initial fingernail sensors were attached using a thin adhesive layer of commonly available cosmetic nail glue. While this approach allowed for easy application and strong adhesion to the nail, the removal could expose the fingernail and finger to a commercially available cosmetic nail removal (acetone-based chemical) for extended times measured in minutes. Therefore, a novel structure and method were developed for rapid healthcare sensor attachment and removal in seconds, which supported both the sensor functional objectives and the biologically and environmentally safe use objectives.

Toenail arsenic species and metallome profiles associated with breast, cervical, prostate, and skin cancer prevalence in the Atlantic Partnership for Tomorrow's Health cohort

Introduction

Chronic exposure to arsenic through drinking water has been linked to several cancers. The metabolism of arsenic is thought to play a key role in arsenic-related carcinogenesis as metabolites of varying toxicity are produced and either stored in or excreted from the body. Atlantic Canada has the highest age-standardized incidence rates of all cancers in the country. This may be due to its high levels of environmental arsenic and the prevalence of unregulated private wells for water consumption. Here, we aimed to characterize the profiles of arsenic species and metallome in the toenails of four cancer groups, compare them to healthy participants (N = 338), and assess potential associations between the profiles with cancer prevalence.

Methods

This study employed a case-control design. Toenail samples and questionnaire data from cases (breast, cervical, prostate, and skin cancers) and controls were sourced from the Atlantic Partnership for Tomorrow's Health (PATH) cohort study. The levels of arsenic species were measured using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) paired with High Performance Liquid Chromatography (HPLC) and total concentrations of metallome (23 metals) were determined by ICP-MS separately. Multivariate analyses were conducted to compare cases with controls within each cancer group.

Results

Arsenic speciation profiles varied by cancer type and were significantly different between cases and controls in the breast (p = 0.0330), cervical (p = 0.0228), and skin (p = 0.0228) cancer groups. In addition, the profiles of metallome (nine metals) were significantly differentiated in the prostate (p = 0.0244) and skin (p = 0.0321) cancer groups, with higher zinc concentrations among cases compared to controls.

Conclusion

History of cancer diagnosis was associated with specific profiles of arsenic species and metallome. Our results indicate that arsenic methylation and zinc levels, as measured in toenails, may be an important biomarker for cancer prevalence. Further research is needed to use toenails as a prognostic measure of arsenic-and other metal-induced cancer.

Current therapeutic insights regarding problematic fingernails and toenails in the Republic of Korea

BACKGROUND

Problematic nails and toenails are infected by germs and increasingly have many causes.

AIMS

To investigate the types and treatment of problematic nails and toenails, we focused on bacteria that may appear in problematic nail toenail symptoms.

METHODS

We have searched for PubMed and Google Scholar and correlated the words Onychomycosis, Tinea ungium, Melanonychia, and ingrown toenail related to symptoms.

RESULTS

To measure onychomycosis, KOH tests and fungal culture tests will be used. Treatment can be treated with full-body treatment using anti-fungal agents and local treatment (laser therapy) that can minimize the side effects. A biopsy should be performed when Melanonychia is diagnosed with brown or black pigments on the patient's fingernail plate. Moreover, ingrown toenail surgical treatment can be improved by acquired lifestyle.

CONCLUSIONS

There are many different types of treatments, but many studies show that problematic nail and toenail improvement periods are long and treatment success rates are low.

Biomarkers for occupational manganese exposure

Long-term inhalation exposure to manganese (Mn) metal or its inorganic compounds can result in manganism or subclinical neurofunctional deficits. Studies have described affected workers in Mn dioxide mining, Mn-containing ore crushing and milling facilities, manufacturing of dry-cell batteries, Mn steel and alloy production plants, and in welders. The objective of this study was to critically review existing evidence on the reliability of potential biomarkers of Mn exposure, specifically the relationship between inhalation exposure to Mn particulates in different occupational settings and Mn concentrations in blood and other biological fluids and tissues, with a particular focus on whole blood as a potentially useful medium for measuring internal tissue dose. We also examined available evidence on the relationship between Mn levels in blood and adverse clinical and subclinical neurotoxic outcomes. Three bibliographic databases were searched for relevant studies and identified references were screened by two independent reviewers. Of the 6338 unique references identified, 76 articles were retained for data abstraction. Findings indicate that the relationships between Mn in blood and both external Mn exposure indices and neurofunctional impairments are limited and inconsistent. Different sources of exposure to Mn compounds, heterogeneity in the methodological approaches, and inadequate reporting of essential information limited direct comparison of the reported findings. Among the Mn-exposure biomarkers considered in this review - including biomarkers in blood, plasma, serum, erythrocytes, urine, bone, toenails, fingernails, hair, saliva - biomarkers in whole blood may provide to be most useful in Mn biomonitoring and risk assessment.

Biomarkers of environmental manganese exposure

We conducted a critical review on biomarkers of environmental manganese (Mn) exposure to answer the following questions: 1) are there reliable biomarkers of internal Mn exposure (Mn in biological matrices) associated with external metrics of Mn exposure (Mn in environmental media)? and 2) are there accurate reference values (RVs) for Mn in biological matrices? Three bibliographic databases were searched for relevant references and identified references were screened by two independent reviewers. Of the 6342 unique references identified, 86 articles were retained for data abstraction. Our analysis of currently available evidence suggests that Mn levels in blood and urine are not useful biomarkers of Mn exposure in non-occupational settings. The strength of the association between Mn in environmental media and saliva was variable. Findings regarding the utility of hair Mn as a biomarker of environmental Mn exposure are inconsistent. Measurements of Mn in teeth are technically challenging and findings on Mn in tooth components are scarce. In non-occupationally exposed individuals, bone Mn measurements using in vivo neutron activation analysis (IVNAA) are associated with large uncertainties. Findings suggest that Mn in nails may reflect Mn in environmental media and discriminate between groups of individuals exposed to different environmental Mn levels, although more research is needed. Currently, there is no strong evidence for any biological matrix as a valid biomarker of Mn exposure in non-occupational settings. Because of methodological limitations in studies aimed at derivation of RVs for Mn in biological materials, accurate RVs are scarce.

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

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.

Comparative Evaluation of Hair, Fingernails, and Toenails as Biomarkers of Fluoride Exposure: A Cross-Sectional Study

Background

The increased prevalence of fluorosis has led to a search for biomarkers of fluoride exposure. Among the biomarkers of sub-chronic exposure to fluoride, hair, fingernails, and toenails have the advantage of being noninvasively collected, easily transported, and stored.

Objective

The objective of this study was to comparatively evaluate coronal hair, fingernails, and toenails as biomarkers of fluoride exposure from drinking water; the study was designed as a population-based observational cross-sectional study.

Materials and Methods

A population-based observational cross-sectional study was conducted in 60 children (20 subjects per group) of ages 12-17 years in three villages of Nilakottai block, Dindigul district, Tamil Nadu, India (Thomaspuram, Bangalapatti, and Singampatti). The fluoride concentration in the household drinking water was analyzed and compared with the fluoride content in the coronal hair, fingernail, and toenail clippings, which was estimated by potentiometric method (fluoride-ion-selective electrode) and expressed in ppm (parts per million). A two-tailed probability value of P < 0.05 was considered significant.

Results

The mean fluoride concentration in drinking water was 0.63ppm in Thomaspuram, 1.63ppm in Bangalapatti, and 2.92ppm in Singampatti. The mean fluoride content in hair samples was 2.84ppm, 4.67ppm, and 6.53ppm; fingernail clippings was 2.99ppm, 4.94ppm, and 6.84ppm; and toenail clippings was estimated as 3.13ppm, 5.10ppm, and 7.24ppm in Thomaspuram, Bangalapatti, and Singampatti residents, respectively. The mean fluoride content in the hair, fingernails, and toenails was significantly higher as compared to the mean fluoride content in the drinking water (viz., toenail fluoride > fingernail fluoride > hair fluoride).

Conclusion

Coronal hair, fingernails, and toenails are useful biomarkers for both sub-chronic and chronic fluoride exposure from drinking water. Due to ample sample availability and the highest fluoride content, toenails are the most suitable biomarkers of fluoride exposure from drinking water.

Biomonitoring of Metals in Children Living in an Urban Area and Close to Waste Incinerators

The impact of waste incinerators is usually examined by measuring environmental pollutants. Biomonitoring has been limited, until now, to few metals and to adults. We explored accumulation of a comprehensive panel of metals in children free-living in an urban area hosting two waste incinerators. Children were divided by georeferentiation in exposed and control groups, and toenail concentrations of 23 metals were thereafter assessed. The percentage of children having toenail metal concentrations above the limit of detection was higher in exposed children than in controls for Al, Ba, Mn, Cu, and V. Exposed children had higher absolute concentrations of Ba, Mn, Cu, and V, as compared with those living in the reference area. The Tobit regression identified living in the exposed area as a significant predictor of Ba, Ni, Cu, Mn, and V concentrations, after adjusting for covariates. The concentrations of Ba, Mn, Ni, and Cu correlated with each other, suggesting a possible common source of emission. Exposure to emissions derived from waste incinerators in an urban setting can lead to body accumulation of specific metals in children. Toenail metal concentration should be considered a noninvasive and adequate biomonitoring tool and an early warning indicator which should integrate the environmental monitoring of pollutants.

Toenail-Based Metal Concentrations and Young-Onset Breast Cancer

Several metals have carcinogenic properties, but their associations with breast cancer are not established. We studied cadmium, a metalloestrogen, and 9 other metals-arsenic, cobalt, chromium, copper, mercury, molybdenum, lead, tin, and vanadium--in relation to young-onset breast cancer (diagnosis age <50 years), which tends to be more aggressive than and have a different risk profile from later-onset disease. Recent metal exposure was measured by assessing element concentrations, via inductively coupled plasma mass spectrometry, in toenail clippings of 1,217 disease-discordant sister pairs in the US-based Sister (2003-2009) and Two Sister (2008-2010) studies. Conditional logistic regression was used to calculate odds ratios and 95% confidence intervals. After correcting for differential calendar time of sample collection, no statistically significant associations were observed between any metals and breast cancer. Vanadium had the largest odds ratio (for fourth vs. first quartile, odds ratio = 1.54, 95% confidence interval: 0.75, 3.16; P for trend = 0.21). The association between cadmium and young-onset breast cancer was near null, with no evidence of a dose-response relationship (for fourth vs. first quartile, odds ratio = 0.95, 95% confidence interval: 0.64, 1.43; P for trend = 0.64). Positive associations between urinary cadmium concentrations and breast cancer have been reported in case-control studies, but we observed no such association between young-onset breast cancer and toenail concentrations of any assessed metals.

Toenail-Based Metal Concentrations and Young-Onset Breast Cancer

Several metals have carcinogenic properties, but their associations with breast cancer are not established. We studied cadmium, a metalloestrogen, and 9 other metals-arsenic, cobalt, chromium, copper, mercury, molybdenum, lead, tin, and vanadium--in relation to young-onset breast cancer (diagnosis age <50 years), which tends to be more aggressive than and have a different risk profile from later-onset disease. Recent metal exposure was measured by assessing element concentrations, via inductively coupled plasma mass spectrometry, in toenail clippings of 1,217 disease-discordant sister pairs in the US-based Sister (2003-2009) and Two Sister (2008-2010) studies. Conditional logistic regression was used to calculate odds ratios and 95% confidence intervals. After correcting for differential calendar time of sample collection, no statistically significant associations were observed between any metals and breast cancer. Vanadium had the largest odds ratio (for fourth vs. first quartile, odds ratio = 1.36, 95% confidence interval: 0.84, 2.21; P for trend = 0.17). Cadmium was associated with a small increase in risk, with no evidence of a dose-response relationship (for fourth vs. first quartile, odds ratio = 1.15, 95% confidence interval: 0.82, 1.60; P for trend = 0.67). Positive associations between urinary cadmium concentrations and breast cancer have been reported in case-control studies, but we observed no such association between young-onset breast cancer and toenail concentrations of any assessed metals.

Do Post-breast Cancer Diagnosis Toenail Trace Element Concentrations Reflect Prediagnostic Concentrations?

BACKGROUND

Exposure to trace elements may affect health, including breast cancer risk. Trace element levels in toenails are potentially useful biomarkers of exposure, but their reliability is not established. We assessed the reproducibility of toenail element concentrations over time and whether concentrations change following a breast cancer diagnosis.

METHODS

We assessed trace element levels in toenails collected at two time points from 221 women (111 with and 110 without an intervening breast cancer diagnosis). We measured levels of arsenic, cadmium, chromium, cobalt, copper, iron, mercury, manganese, molybdenum, nickel, lead, antimony, selenium, tin, vanadium, and zinc using inductively coupled plasma mass spectrometry in samples collected at baseline and 4-10 years later. We compared trace element concentrations over time using Spearman's rank correlation coefficient (R). We used linear models to examine the magnitude and direction of changes and the influence of a breast cancer diagnosis.

RESULTS

Overall, we observed positive correlations (R = 0.18-0.71) between paired samples for all trace elements. However, nickel (R = -0.02) and antimony (R = 0.12) were not correlated among cases. We observed decreases in cadmium, chromium, mercury, manganese, molybdenum, nickel, and lead between baseline and follow-up, but case status was unrelated to these changes. The declines are consistent with decreases over calendar time rather than age time.

CONCLUSIONS

Toenail trace element concentrations were correlated over time, but many elements showed systematic decreases by calendar year. Aside from nickel and antimony, postdiagnostic toenail levels correlated with prediagnostic levels, providing support for using postdiagnostic toenail samples in retrospective studies.

Toenail Manganese: A Sensitive and Specific Biomarker of Exposure to Manganese in Career Welders

Manganese (Mn) is an essential trace metal. It is also a component of welding fume. Chronic inhalation of manganese from welding fume has been associated with decreased neurological function. Currently, there is not a universally recognized biomarker for Mn exposure; however, hair and toenails have shown promise. In a cohort of 45 male welders and 35 age-matched factory control subjects, we assessed the sensitivity and specificity of toenail Mn to distinguish occupationally exposed subjects from unexposed controls. Further we examined the exposure time window that best correlates with the proposed biomarker, and investigated if non-occupational exposure factors impacted toenail Mn concentrations. Toenail clippings were analyzed for Mn using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Exposure to respirable Mn-containing particles (<4 µm) was estimated using an exposure model that combines personal air monitoring, work history information, and dietary intake to estimate an individual's exposure to Mn from inhalation of welding fume. We assessed the group differences in toenail concentrations using a Student's t-test between welders and control subjects and performed a receiver operating characteristic (ROC) curve analysis to identify a threshold in toenail concentration that has the highest sensitivity and specificity in distinguishing welders from control subjects. Additionally, we performed mixed-model regressions to investigate the association between different exposure windows and toenail Mn concentrations. We observed that toenail Mn concentrations were significantly elevated among welders compared to control subjects (6.87 ± 2.56 versus 2.70 ± 1.70 µg g-1; P < 0.001). Our results show that using a toenail Mn concentration of 4.14 µg g-1 as cutoff allows for discriminating between controls and welders with 91% specificity and 94% sensitivity [area under curve (AUC) = 0.98]. Additionally, we found that a threshold of 4.66 µg g-1 toenail Mn concentration enables a 90% sensitive and 90% specific discrimination (AUC = 0.96) between subjects with average exposure above or below the American Conference of Governmental Industrial Hygienist (ACGIH) Threshold Limit Value (TLV) of 0.02 mg m-3 during the exposure window of 7-12 months prior to the nail being clipped. Investigating which exposure window was best reflected by toenail Mn reproduced the result from another study of toenail Mn being significantly (P < 0.001) associated with exposure 7-12 months prior to the nail being clipped. Lastly, we found that dietary intake, body mass index, age, smoking status, and ethnicity had no significant effect on toenail Mn concentrations. Our results suggest that toenail Mn is a sensitive, specific, and easy-to-acquire biomarker of Mn exposure, which is feasible to be used in an industrial welder population.

Manganese in toenails is associated with hearing loss at high frequencies in humans

PURPOSE

Elevated hearing thresholds from high frequencies are known to be one of the hallmarks of age-related hearing loss. Our recent study showed accumulation of manganese (Mn) in inner ears resulting in acceleration of age-related hearing loss in mice orally exposed to Mn. However, there is no evidence showing an association between Mn in non-invasive biological samples and hearing loss in humans evaluated by pure tone audiometry (PTA). In this study, we evaluated Mn in non-invasive biological samples as a possible biomarker for hearing loss in humans.

MATERIALS AND METHODS

We determined hearing levels by PTA and Mn levels in toenails, hair and urine with an inductively coupled plasma mass spectrometer (ICP-MS) in 145 healthy subjects in Bangladesh.

RESULTS

Multivariable analyses showed that Mn levels in toenails, but not in hair and urine samples, were significantly associated with hearing loss at 8 kHz and 12 kHz. Moreover, our experimental study showed a significant correlation between Mn levels in inner ears and nails, but not hair, in mice orally exposed to Mn.

CONCLUSIONS

The results provide novel evidence that Mn in toenails is a possible biomarker for hearing loss at high frequencies in humans.

[Effect of 0.9-ms 1064-nm Nd:YAG laser combined with itraconazole for treatment of toenail onychomycosis]

OBJECTIVE

To evaluate the efficacy and safety of 0.9-ms 1064-nm Nd:YAG laser alone or combined with itraconazole for treatment of toenail onychomycosis.

METHODS

A total of 37 patients with onychomycosis (178 toenails) were randomly assigned to groups A and B, and each group was further divided into different subgroups according to the Scoring Clinical Index of Onychomycosis (SCIO) and Onychomycosis Severity Index (OSI) scoring. All the patients were treated with 0.9-ms Nd:YAG laser once a week for 8 times. The patients in group A were treated with laser alone, and those in group B were treated with laser combined with itraconazole. The clinical effect, clinical scores, appearance of the toenails and adverse reactions in the two groups were analyzed, and the patients' satisfaction rate was also investigated.

RESULTS

At the 12th months of follow-up, the clinical response rate and mycological cure rate in group A were 31.33% and 30.00%, respectively, similar to the rates in group B (35.79% and 41.18%, respectively) (P>0.05). After the treatments, the SCIO and OSI scores showed no significant changes in group A (P>0.05) but both increased significantly in group B (P<0.05). The response rates did not differ significantly among the subgroups with SCIO<12 or with OSI<16 (P>0.05), but showed significant differences among the subgroups with SCIO≥12 or with OSI≥16 (P<0.05). Of the total of 178 toenails, 33.71%, 74.72% and 70.79% toenails showed improvements in terms of clear nail growth, shape and color, respectively. The overall patients' satisfaction rate was 62.16%, and no adverse reactions related with the therapy were recorded in these patients.

CONCLUSION

For treatment of toenail onychomycosis, 0.9-ms 1064-nm Nd:YAG laser can effectively improve the aesthetic appearance of the toenails, and a combined treatment with Nd:YAG laser and itraconazole can be better option in severe cases of onychomycosis.

1340nm LASER THERAPY FOR ONYCHOMYCOSIS: Negative Results of Prospective Treatment of 72 Toenails and a Literature Review

Onychomycosis is an infection of the nail plate by fungal microorganisms. This infection has an important social impact on women and men and poses a major challenge for its treatment. The traditional treatment of onychomycosis involves the use of topical and oral antifungal agents. However, the presence of adverse effects frequently associated with oral antifungals, their high cost, and their potential interactions with other drugs reflect some of the problems associated with conventional therapy. The current report details the evaluation of a 1340nm laser as monotherapy for toenails affected by onychomycosis. A 1340nm, neodymium-yttrium:yttrium-aluminum-perovskite (Nd:YAP) (e) laser (Etherea, Industra technologies, Brazil) was used with the following treatment parameters: a spot size of 6mm, pulse duration of 5ms, fluence of 22 to 25J/cm2, and repetition rate of 1.5 to 2.5Hz. In all, 72 toenails were evaluated in 30 patients who had clinical and laboratory confirmation of onychomycosis. The efficacy of treatment was measured by the degree of patient satisfaction on a scale of 0 to 10 and by mycological cure evidenced by direct mycological exam and culture. Considering three applications of laser therapy and a clinical/laboratory follow-up period of 12 weeks, monotherapy with 1340nm laser was not effective, since 93.3 percent of the assessed patients remained without clinical and mycological cure. Despite reports of variable success rates with the use of different lasers for the treatment of onychomycosis, it is not yet possible to state that this therapeutic alternative is indicated for the treatment of these infections, mainly due to the limited number of patients and/or nail plates evaluated and the controversial results described in the literature.

Environmental and Genetic Factors on the Development of Onychomycosis

Since the early 20th century, onychomycosis originated with the onset of war, the use of occlusive footwear, and the mass migration of people by transportation in the United States. Even though onychomycosis has a high prevalence in the US, other parts of the world including Canada, West Africa, Southeast Asia, Northern Australia, and Europe have been well documented with cases of fungal toenail infection in their environments. Trichophyton rubrum (T. rubrum) is the major dermatophyte responsible for toenail fungal infection and is typically diagnosed in conjunction with tinea pedis, especially in individuals older than 60 years. Gender roles, age, cultural habits, shoe gear, sports activities, and genetic predisposition all contribute to the different presentation of onychomycosis in these areas where organisms like dermatophytes, candida, and molds were isolated in a variety of cases. Despite the differences in isolated pathogens, treatment outcomes remained consistent. This literature review discusses the influence of tinea pedis, genetics, shoe gear, sports, and age on the development of onychomycosis.

Selenium toxicity from a misformulated dietary supplement, adverse health effects, and the temporal response in the nail biologic monitor

Use of dietary supplements in the U.S. has increased steadily over the last 25 years. While misformulation is uncommon, the consequences can be serious. A March 2008 voluntary market recall removed supplement products responsible for the most serious selenium toxicity outbreak that has occurred in the U.S. We quantified selenium concentrations in the misformulated supplement products, measured the temporal response in the nail biologic monitor, and associated exposure to self-reported selenosis symptoms. Subjects recruited through state health departments and referrals provided samples of the misformulated supplement products, exposure information, monthly toenail and or fingernail clippings or onycholysitic nail fragments, and listed their newly onset adverse health effects attributed to selenium toxicity. Ninety-seven subjects enrolled and submitted at least one test sample. Peak selenium concentrations (up to 18.3 and 44.1 μg/g for toenails and fingernails, respectively) were measured. Multiple samples (52 total) of all six recalled supplement lots were analyzed ranging from 22,300 to 32,200 μg selenium per daily dose. Average consumption was 30.9 ± 13.9 doses; 73 subjects provided follow-up data on selenosis symptoms at 2.50 ± 0.14 years. Nail samples accurately reflect exposure in this selenium toxicity outbreak, which resulted in long-term/permanent adverse health effects.