A prospective study of selenium status and breast cancer risk

Low dietary intake of selenium has been proposed as a risk factor for breast cancer. To address this hypothesis, we collected toenail clippings from 62,641 women in the Nurses' Health Study cohort who were free from cancer (other than nonmelanoma skin cancer) in 1982 and 1983. The selenium concentration in nails has been shown to reflect dietary intake of selenium. During 53 months of follow-up, 434 cases of breast cancer were diagnosed among women who had submitted a set of toenail clippings, and we matched one control free from breast and other cancers to each case. The mean selenium level in toenails in the cases (0.823 microgram/g; SD, 0.197) was almost identical to that of the controls (0.821 microgram/g; SD, 0.174). After controlling for known breast cancer risk factors, the relative risk for women in the highest quintile of selenium as compared with the lowest quintile was 1.10 (95% confidence interval, 0.70 to 1.72) and there was no trend across quintiles. Results were similar for both premenopausal and postmenopausal women. Although these data do not exclude a possible influence of selenium intake before adulthood on subsequent risk of breast cancer, selenium intake later in life is not likely to be an important factor in the etiology of breast cancer.

Predictors of selenium concentration in human toenails

To assess the validity of the selenium concentration in human toenails as a measure of selenium intake and to determine other correlates of toenail selenium level, the authors examined the predictors of toenail selenium within two subgroups of a large cohort study of US women. Mean toenail selenium was higher among 38 consumers of selenium supplements (0.904 micrograms/g, standard deviation (SD) 0.217) than among 96 nonusers (0.748 micrograms/g, SD 0.149; p less than 0.001), and a dose-response relation was observed among supplement users (Spearman's r = 0.32; p = 0.05). In a second subgroup of 677 women, selenium supplement use was also associated with higher mean toenail selenium (0.906 micrograms/g, SD 0.214, among 18 users and 0.801 micrograms/g, SD 0.148, among 659 nonusers; p = 0.02), and the dose-response relation was also significant (Spearman's r = 0.50; p = 0.03). The geographic variation in toenail selenium levels was consistent with the geographic distribution of selenium in forage crops. Toenail selenium declined with age and was significantly reduced among cigarette smokers (mean = 0.746, SD 0.124, among 146 current smokers and mean = 0.817, SD 0.159, among 311 never smokers; p less than 0.001) but was not materially affected by alcohol consumption. A dietary selenium score calculated from a food frequency questionnaire failed to predict toenail selenium level, demonstrating the suspected inability of diet questionnaires to measure individual selenium intake because of the highly variable selenium composition of different samples of the same food.(ABSTRACT TRUNCATED AT 250 WORDS)

Selenium in diet, blood, and toenails in relation to breast cancer: a case-control study

The association between breast cancer and selenium, measured in the diet, plasma, erythrocytes, and toenails, was investigated in a case-control study in the Netherlands during 1985-1987. Dietary selenium intake was assessed by a structured dietary history technique among 133 breast cancer cases and 238 population controls. Absolute and energy-adjusted selenium intake and selenium concentrations in plasma, erythrocytes, and toenails were similar in cases and controls. The multivariate adjusted odds ratios of breast cancer for subjects in the lowest quartile compared with the highest quartile were 1.6 (95% confidence interval (CI) 0.8-3.4) for dietary selenium, 2.0 (95% CI 0.9-4.4) for plasma selenium, 0.9 (95% CI 0.4-1.9) for erythrocyte selenium, and 1.1 (95% CI 0.6-2.1) for toenail selenium. No statistically significant trend was observed in the odds ratios for any of the four indicators of selenium. These results do not suggest a substantial association between selenium and breast cancer for both short- and long-term markers of selenium status.

Fluoride in the urine, hair, and nails of phosphate fertiliser workers

The fluoride content in the urine, hair, and nails of 106 workers employed in a phosphate fertiliser plant was significantly raised above the control level. Positive correlations were found between the group means for concentrations of fluorides in urine and hair (r = 0.77), urine and nails (r = 0.99), and hair and nails (r = 0.70). Individual values in the whole population gave significant correlations between concentrations in urine and nails (r = 0.73). The obtained results indicate that the fluoride content in hair and nails may be used as an indicator of occupational exposure to fluorides.

Cholesterol sulphate levels in the hair and nails of patients with recessive X-linked ichthyosis

Cholesterol sulphate (CS) has been suggested as an intercellular glue for corneocyte-corneocyte cohesion from studies on patients with recessive X-linked ichthyosis (RXLI). Pathological stratum corneum of RXLI patients was found to show a significant elevation of CS. In the present study hair and nails, unaffected keratinized tissues in RXLI patients, were examined for CS levels. The results demonstrated significantly elevated CS levels in both tissues in RXLI patients (P less than 0.001). In particular the mean CS level in the hair of RXLI patients was five times greater than normal. The present study suggests that hair is a useful material for the diagnosis of RXLI.

Comparison of human hair and nail low-sulfur protein compositions on two-dimensional electrophoresis

Compositions of human normal hair and nail low-sulfur proteins were compared using two-dimensional electrophoresis of their S-carboxymethylated (SCM) derivatives. Six SCM low-sulfur protein components with molecular weights (MWs) of 76,000, 73,000, 72,000, 64,000, 61,000 and 55,000 were common to the hair and nail. One component with a MW of 61,000 was specific to hair, and two components, both with a MW of 50,000, were specific to nail.

Comparison of hair with nail as index media for biological monitoring of mercury

Mercury in hair and nails was determined with speciation of chemical forms of mercury. Scalp hair and toenails were sampled once and fingernails were sampled three times from the subjects (18 males and 5 females) whose age ranged from 23 to 56 yr. Total mercury (THg) and inorganic mercury (IHg) were determined by Magos' method with modifications. No sex-related differences were found in mercury levels in hair and nails. In the fingernail samples of three different formation periods, THg and IHg concentrations remained almost constant. Among the three kinds of index media, the highest THg concentration was found in scalp hair followed by fingernails and toenails in the order given, whereas IHg concentrations in scalp hair were similar as those in fingernails but were lowest in toenails. The percent inorganic to total mercury was higher in fingernails than in hair and toenails, which is likely to reflect a possible external contamination with IHg in fingernails. The higher THg concentration in scalp hair than in nails may be attributable to the difference in the chemical composition, in particular sulphur content, and in the blood flow during the formation of hair and nails.

Analysis of methamphetamine in hair, nail, sweat, and saliva by mass fragmentography

A method for the detection and quantitation of methamphetamine and its major metabolite in hair, nails, sweat, and saliva from habitual users of methamphetamine by mass fragmentography has been developed. Hair and nail samples were washed with water and methanol to remove the external contamination, processed with 0.6M HCl, alkalinized, and extracted with CHCl3/isopropanol (3:1 v/v). Sweat and saliva samples were extracted with methanol. After trifluoroacetyl derivatization, the samples were analyzed by mass fragmentography. Methamphetamine and its major metabolite, amphetamine, were detected in hair, nail, and sweat samples, but methamphetamine alone was detected in saliva samples.

Glycosylated proteins of skin, nail and hair: application as an index for long-term control of diabetes mellitus

The purpose of the present study was to compare the degrees of nonenzymatically glycosylated proteins in the skin (stratum corneum), the nail, the hair, and hemoglobin obtained simultaneously from the same subject and to evaluate the most useful sample for management of diabetic complications. Fifty-one diabetic patients and 20 control patients were examined, utilizing furosine determination. Furosine value of the skin in diabetics was 2.14 +/- 1.70%, whereas that in controls was 1.65 +/- 0.47%. Furosine value of the nail in diabetics was 6.67 +/- 3.30%, whereas that in controls was 4.16 +/- 1.62%. Furosine value of the hair in diabetics was 1.30 +/- 1.11%, whereas that in controls was 1.29 +/- 1.71%. Close correlations were detected between HbA1 (glycosylated hemoglobin) and furosine of the nail (r = 0.58, p less than 0.001), HbA1 and furosine of the skin (r = 0.48, p less than 0.001), and HbA1 and furosine of the hair (r = 0.43, p less than 0.01); however, poor correlations were found between furosine of the hair and the skin (r = 0.35, p less than 0.05) and furosine of the nail and the hair (r = 0.33, p less than 0.05). Furosine of the nail was significantly correlated with the FBS (fasting blood sugar) of the same time, previous 6, and previous 12 months. Furosine value of the nail, we believe, is the most useful indicator for evaluating long term control of diabetics and may provide useful information for management of diabetic complications.

Quantitative trace element analysis of human nails with external beam PIXE

External beam PIXE (Particle Induced X-ray Emission) analysis with a proton beam of 2.4 MeV was used to study trace element concentrations in human nails. The suitability of PIXE analysis regarding nail samples without any pretreatment besides washing was investigated. The main emphasis has been on the ability to obtain absolute concentration values and a new accurate method for nail sample standardization has been developed. Concentration values for the elements Ca, Cr, Mn, Fe, Ni, Cu, Zn, Se, Br, and Pb were determined from human nail samples. A comparison was made with nail samples taken from different fingers and toes to monitor intraindividual variation, and nails of different healthy individuals to get a view of the interindividual differences. The concentrations were also measured in relation to time in order to observe any possible short-term changes. The results are compared with the previous studies reported in the literature. The nail analysis is also compared to hair analysis in terms of detection limits, number of elements determinable, and standardization of the results.

Decreased selenium levels in acute myocardial infarction

To study the association between selenium status and the risk of myocardial infarction, we compared plasma, erythrocyte, and toenail selenium levels and the activity of erythrocyte glutathione peroxidase among 84 patients with acute myocardial infarction and 84 population controls. Mean concentrations of all selenium measurements were lower in cases than controls. The differences were statistically significant, except for the plasma selenium level. A positive trend in the risk of acute myocardial infarction from high to low toenail selenium levels was observed, which persisted after adjustment for other risk factors for myocardial infarction. In contrast, erythrocyte glutathione peroxidase activity was significantly higher in cases than controls (31.3 +/- 8.4 U/g of hemoglobin and 28.0 +/- 8.1 U/g of hemoglobin, respectively). Because the toenail selenium level reflects blood levels up to one year before sampling, these findings suggest that a low selenium status was present before the infarction and, thus, may be of etiologic relevance. The higher glutathione peroxidase activity in the cases may be interpreted as a defense against increased oxidant stress either preceding or following the acute event.

Human scalp hair as evidence of individual dosage history of haloperidol: method and retrospective study

Hair samples and morning pre-dose plasma were collected from 40 patients who had received fixed daily doses of haloperidol for more than four months and whose compliance was good. After washing, 1 to 2 cm-long portions nearest to the roots of 2 to 3 strands of hair were completely dissolved in 2.5N NaOH. Haloperidol in that sample or alkalinised plasma was extracted and measured by RIA. Haloperidol concentrations in hair correlated well both with the trough concentration in plasma at steady-state (r = 0.772, n = 39) and with the daily dose (r = 0.555, n = 40). Another keratinized tissue, nail, was also collected from 20 of the 40 patients and the haloperidol level was compared with that in hair. The former was only about 4.3% of the latter and was significantly correlated only with the daily dose (r = 0.525, n = 20). Hair from 10 other patients in whom the dosage of haloperidol had been changed within a few months prior to sampling the hair was cut into 0.5 or 1 cm-long portions from the roots and the drug concentration in each portion was measured. If hairs were assumed to grow at 1 cm/month, a history of individual dosage could be deduced in 9 of the 10 patients from the distribution of drug level along the length of the hair. The results suggest that human scalp hair could serve as a useful tool for monitoring individual dosage history over several months, or in demonstrating exposure or non-exposure of a patient to a drug.

Utilization and requirement of dietary protein taking into account the dermal and miscellaneous nitrogen losses in Japanese women

Utilization and requirement of mixed protein in the conventional Japanese diet and the obligatory integumental and miscellaneous nitrogen losses were measured in female subjects. Twelve female students aged 18 to 24 years were given conventional low-protein diets at N intake levels of 50, 70, and 90 mg/kg/day for 10 days. Constituents of the diets corresponded to those of average intake of the Japanese in recent years (1982). N balances were estimated and regression equations between N intake (X) and N balance (Y) were calculated by the multiple level-constant variation method. The equation was Y = 0.426X - 40.0 (n = 36, r = 0.615, p less than 0.01) and the intersection of the regression line with zero nitrogen balance was 93.9 +/- 14.3 mg N/kg/day. The mean digestibility was 92.2 +/- 4.7%. In another experimental group, nitrogen losses due to hair, nails, and menstruation in ten Japanese women were 0.624 +/- 0.172, 0.020 +/- 0.005, and 1.76 +/- 0.68 mg/kg/day, respectively. In a third experimental group, mean of the integumental N losses was 2.8 mg/kg/day in both the subjects given a low-protein diet (19 women) and an ordinary-protein diet (4 women). It increased to 12.7 mg N/kg/day when subjects exercised in summer (4 subjects). The protein requirement in the conventional Japanese diet estimated as the sum of the mean requirement of dietary protein and obligatory dermal and miscellaneous nitrogen losses in Japanese women was 99.1 mg N/kg/day or 0.62 g protein/kg/day. The net protein utilization (NPU) of the proteins at the N intake level for N equilibrium was estimated as 48.

Trace element content in fingernails and hair of a nonindustrialized US control population

The concentrations of 17 elements in the nail and hair of 117 subjects from a nonindustrialized environment were determined by instrumental neutron activation analysis (INAA). A new method of statistical treatment that allows for more meaningful use of detection limit values was used to process the concentration data. Geometric means and standard errors are presented for each element, along with a summary of the effects of age, sex, and treatment on the concentration of each element. For nails, these data represent the first comprehensive study for several important elements. Correlations for each element between hair and nail were determined. With few exceptions, concentrations of nonessential trace elements were positively correlated in hair and nail, whereas concentrations of essential elements showed no correlations. The factors affecting concentrations and control levels must be considered in studying alterations in disease states.

X-ray microanalysis of the fingernails in term and preterm infants

The element content of the fingernails of 10 term and 14 preterm infants, clipped for the first time after delivery, was determined by x-ray microanalysis. The results showed a decrease in sulfur and aluminum, and a higher chlorine content in term infants in comparison with preterm ones, the difference being statistically significant. Sodium, potassium, calcium, and zinc content did not differ in the two groups. Copper, iron, magnesium, aluminum, and phosphorus were detected in trace amounts only. Cobalt was not detected in the fingernails of newborns in either group. The elevated content of aluminum in the fingernails of preterm infants may be a clue to the osteopenia observed in these infants.

Formation of radicals by mechanical processes

The application of e.s.r. spectroscopy to the study of radicals formed by mechanical means (grinding, shearing, bending, cutting, etc.) is discussed. Two mechanisms are considered, one being the homolytic breaking of main-chain bonds in polymers, and the other being charge-transfer (tribo-electric effect). The former is thought to occur for high polymers whilst the latter may be important for certain inorganic materials especially ionic solids. Specific examples are given for the generation of radicals by cutting finger nails and by grinding bone. In both cases, well-defined e.s.r. spectra were obtained for which identifications are offered. Possible implications of the mechanical formation of radicals in bone are considered.

The iron content of finger-nails in iron deficient patients

The content of S, Ca, Fe, Cu and Zn in the finger-nails of 17 women with iron deficiency was examined by X-ray microanalysis and compared with that of 17 healthy women. The values for all these elements were similar in both groups. The distribution curve for iron was also similar in both patients and controls. There was no correlation between the iron content of the finger-nails and the serum iron or haemoglobin levels. It is suggested that the iron content of the finger-nails in iron deficient patients does not reflect their iron status.

Selenium levels in nails of premenopausal breast cancer patients assessed prediagnostically in a cohort-nested case-referent study among women screened in the DOM project

To determine the possible role of selenium in the pathogenesis of breast cancer, prediagnostic Se 77 m isotope levels in toenail clippings in premenopausal women were measured. The study was designed as a case-referent study nested in a cohort. Participants were recruited from the DOM-project breast-cancer screening cohorts. No decreased selenium levels were found up to two years prior to diagnosis, nor were Se levels different between prevalent and/or incident breast cancer cases, referents and women with benign breast disease. Se levels measured in nails could not detect women at higher risk for breast cancer. This study does not support the idea that Se supplementation could have a preventive potential for premenopausal breast cancer in women in the Netherlands.

[Determination of antimony in nail and hair by thermal neutron activation analysis]

The concentration of antimony in nail and hair was determined by thermal neutron activation analysis. Samples were collected from the workers of an antimony refinery, inhabitants near the refinery, and residents in control area. They were irradiated by Kyoto University 5 000 kW Reactor for 1 h, and cooled for 30 to 100 days. After cooling, the concentration of Sb in nail and hair was estimated by measuring the intensity of gamma-ray from 124Sb of the samples, then the samples were washed by 0.1% aqueous solution of nonionic surface active agent in an ultrasonic cleaner. The gamma-ray spectrometry was done again (after washing). The concentration of Sb in nail before washing was 730 ppm for the workers, 2.46 ppm for habitants near the refinery, and 0.19 ppm for the control; after washing, it became 230 ppm for the workers, 0.63 ppm for habitants, and 0.09 ppm for the control. The concentration of Sb in hair before and after washing was 222 ppm and 196 ppm for the workers, and 0.21 ppm and 0.15 ppm for the control, respectively.

Levels of arsenic in alcohol-related liver disease

Increased levels of arsenic were found in serum and urine and in hair and nails of patients suffering from alcohol-related liver disease (ALD). Various surveys were conducted in different places to find the cause for high arsenic in ALD. It was found that patients were consuming 'home made brew' which was contaminated with arsenic.

X-ray microanalysis of the fingernails in cirrhotic patients

The element content of clipped nails of 13 patients with liver cirrhosis was examined by X-ray microanalysis, and compared with that of 50 healthy subjects. The results showed a statistically significant increase in the percentage of Na, Mg and P and a slight, but statistically significant decrease in S and Cl. The percentage of K, Ca, Fe, Cu and Zn did not show any difference from that of the controls. The findings indicate that X-ray microanalysis may be a valuable tool for the simultaneous examination of a large number of elements in the fingernails.

Increased fructose-lysine of nail protein and blood glucose control in diabetic patients

Furosine, which was formed by acid hydrolysis of fructose-lysine, was determined and used as an indicator of glycosylated protein. The diabetic patients had significantly higher fructose-lysine levels in finger nails than healthy subjects [10.8 +/- 4.6% (mean +/- S.D.) vs 4.2 +/- 1.1%]. The best correlation was found between the fructose-lysine value and the fasting blood glucose level determined 3 to 5 months before sampling nails in diabetics. These results suggest that the furosine derived from fructose-lysine in finger nails may become an indicator of blood glucose control during the past 3 to 5 months in diabetics.

Definitions of monitoring activities and their relevance for the practice of occupational health

The authors discuss the definitions of environmental monitoring (EM), biological monitoring (BM) and health surveillance (HS) as agreed upon by a CEC/NIOSH/OSHA-seminar in 1980. They emphasize the essential differences in underlying principles. They add a fourth definition of biological effect monitoring (BEM). Each method has its own assets and liabilities. Moreover, EM and BM require another decision-making process (situation-centered) then BEM and HS (client-entered) of measures to be taken. When the differences between the four approaches are not taken into account, valid preventive measures may be hampered.

Physicochemical characterization of the human nail: solvent effects on the permeation of homologous alcohols

To assess how vehicles might influence permeation through human nail, the diffusion of homologous alcohols (methanol to decanol) administered as neat liquids through finger nail plate has been studied using in-vitro diffusion cell methods and compared with permeation data for the same compounds in aqueous media. Permeation rates of the homologous alcohols through lipid depleted nail plate have also been assessed and the influences of dimethylsulphoxide (DMSO) and isopropyl alcohol on permeation rates of methanol and hexanol have been examined. With the exception of methanol, permeability coefficients are uniformly about five-fold smaller when the alcohols are undiluted than when they are applied in water. Overall parallelism in the permeability profiles under these separate circumstances of application is an indication that the external concentrations of the alcohols themselves are a determinant of their permeation velocities through the nail plate matrix. The even separation of the profiles suggests a facilitating role of water within the nail matrix. Chloroform/methanol delipidization of the nail led to increased penetration rates of water, methanol, ethanol and butanol. On the other hand, it caused a six-fold decrease in the permeation rate of decanol. Application of methanol and hexanol in DMSO somewhat retards their rates of permeation. Isopropyl alcohol also slows the permeation rate of hexanol but has little influence on that of methanol. Thus it appears that solvents which tend to promote diffusion through the skin horny layer have little promise as accelerants of nail plate permeability.

Hyperpigmentation of the skin associated with minocycline therapy

Skin biopsy specimens and discolored fingernails from minocycline-treated patients were examined by light and electron microscopy, histochemistry, and energy-dispersive x-ray analysis. Both hyperpigmented and adjacent normally pigmented skin samples contained pigment-laden macrophages in the dermis, although these cells were more numerous in the hyperpigmented skin samples. Elemental analysis showed that both pigment deposits and stratum corneum of hyperpigmented skin samples contained iron and calcium. Discolored areas of fingernails from a minocycline-treated patient also contained iron and calcium. Both skin and nail discoloration were possibly due to the presence of an iron chelate of minocycline and/or quinoid derivatives of minocycline. The presence of iron-containing pigment in normal as well as hyperpigmented skin may have predisposed to formation of minocycline-associated pigment in these patients.

Physiological indicators of fluoride exposure and utilization: an epidemiological study

Individual samples of urine, fingernails, head-hair, saliva, plaque and enamel were collected from three groups of Hungarian children, aged 14 years, who were exposed to contrasting water fluoride levels (less than or equal to 0.11 ppm; 0.5-1.1 ppm; 1.6-3.1 ppm). The mean fluoride concentration of the samples increased consistently and significantly, but mostly non-proportionately, with increasing water fluoride level. With the exception of plaque, the materials examined are considered suitable indicators of exposure to or systemic utilization of fluoride for population groups. Caries experience decreased with increasing fluoride exposure. Dental fluorosis constituted no clinical or aesthetic problem.

X-ray microanalysis of chloride in nails from cystic fibrosis and control patients

Nail clippings from 60 individuals were examined. There were 34 "old" (greater than 16 years) controls, 16 "young" controls and 10 CF patients. In regard to elements found, Si and Al were considered as exogenous contamination. Other elements examined were variable in both control and CF. Examination of the Cl levels among the 3 groups showed a highly significant difference between the mean Cl integral values of the young controls (619 integral) and the CF patients (2956 integral). The results of the older control population ranged from 0-905 integral with a mean of 269 integral. We found no age or sex difference in the amount of Cl or any other element from either the CF or control population. Results show that the x-ray energy dispersive system (EDS) is very useful in studying the Cl in nails. We found that examination of nails frozen in liquid nitrogen followed by fracturing without prior washing was the preferred method. Although the results of this study clearly show statistically the value of EDS analysis of Cl in the diagnosis of CF, we must await further study of a larger group of patients to determine its usefulness in evaluating individual patients, particularly newborns.

A comparative study of the immunologic properties of hoof and nail fibrous proteins

We have studied the localization of epidermal (soft) and nail and hoof (hard) fibrous keratins in the various anatomic regions of bovine hoof and human nail. Indirect immunofluorescence was performed on frozen sections of various parts of hoof and nail with antibodies demonstrated to be specific for hard and soft fibrous keratins by the Ouchterlony technique. The antibody to hard fibrous keratin reacted with the upper region of hoof bed and matrix tissue but not perihoof epidermis. The antibody to soft fibrous keratin reacted with hoof bed, matrix tissue, and perihoof epidermis. Electrophoretic analysis of the fibrous proteins of hoof bed indicated they contained both soft and hard fibrous keratins while matrix tissue contained only hard keratins. Immunoblot analysis of matrix fibrous proteins indicated that most of the polypeptides reacted with both antibodies. These results indicate that the antibody to soft fibrous keratin cross-reacts with hard fibrous keratin but the antibody to hard fibrous keratin appears to be specific. Immunologic studies, therefore, must be correlated with electrophoretic studies in order to define the localization of the various types of fibrous keratins. Similar results were obtained with human nail.

Seasonal arsenic exposure from burning chromium-copper-arsenate-treated wood

All eight members of a rural Wisconsin family experienced recurring neurological and medical illness over three years, especially during the winter months. Arsenic, in concentrations of 12 to 87 ppm, was noted in the hair of the mother and father, and analysis of hair and fingernails of all family members demonstrated pathological levels of arsenic. For four years the five-room home had been heated with a small wood stove in which outdoor or marine plywood and wood remnants had been preferentially burned. Stove ashes that contained more than 1,000 ppm of arsenic contaminated the living area, and the ratio of copper, chromium, and arsenic pentoxide in this ash matched the ratio used in the chromium-copper-arsenate-treated wood.

Nails as useful materials for detection of methamphetamine or amphetamine abuse

Methamphetamine and amphetamine could be demonstrated in nail clippings obtained from methamphetamine users by sensitive gas chromatography/chemical ionization mass spectrometry with N-methylbenzylamine as an internal standard. The methamphetamine levels in fingernails were comparable to those in hair. Both stimulants were more concentrated in toenails than in fingernails. The detection of methamphetamine and amphetamine in nails provides an alternative information to that in hair on their past abuse.

Estimation of zinc and other trace elements in the nails of Hungarian adult twin pairs by neutron activation analysis

Nail samples of 157 adult Hungarian twin pairs were examined for different trace elements by neutron activation analysis. Comparing the within-pair-concordance for zinc contents of the twins of different zygosity, a much higher concordance in monozygotes than in dizygotes was observed. The authors suggest the idea that the zinc content in the human organism, at least in some organs, may be genetically controlled.