Mineral concentrations in hair of Belgian elementary school girls: reference values and relationship with food consumption frequencies

Microchemistry of Single Hair Strands Below and Above the Scalp: Impacts of External Contamination on Cuticle and Cortex Layers

External contamination of hair is the most significant challenge to it becoming an accepted matrix for monitoring endogenous metal exposure and nutritional deficiency. Here we use laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to quantify elemental concentrations in hair strands below and above the scalp in the cuticle and cortex layers to determine the extent of external contamination in a reference population. Evidence of hair strand contamination occurred for barium, calcium, iron, magnesium, and strontium in both the outer cuticle and the inner cortex layers, with increasing concentrations from root to tip. Aluminum, boron, copper, lead, and manganese showed significant contamination in the cuticle layer only, suggesting some protection of the inner cortex. Phosphorus and potassium decreased outside the scalp suggesting loss by washing, while chromium, mercury, selenium, sodium, titanium, and zinc showed no evidence of loss or external contamination above the scalp. The results clearly show that for most elements, hair chemistry above the scalp is unreliable for use in interpretation of endogenous exposures or deficiencies, and that the below-scalp portion provides a more accurate monitoring tool. This is the first paper to provide a reference range of elemental hair chemistry that is not impacted by the external environment.

Dietary biomarkers-an update on their validity and applicability in epidemiological studies

The aim of this literature review was to identify and provide a summary update on the validity and applicability of the most promising dietary biomarkers reflecting the intake of important foods in the Western diet for application in epidemiological studies. Many dietary biomarker candidates, reflecting intake of common foods and their specific constituents, have been discovered from intervention and observational studies in humans, but few have been validated. The literature search was targeted for biomarker candidates previously reported to reflect intakes of specific food groups or components that are of major importance in health and disease. Their validity was evaluated according to 8 predefined validation criteria and adapted to epidemiological studies; we summarized the findings and listed the most promising food intake biomarkers based on the evaluation. Biomarker candidates for alcohol, cereals, coffee, dairy, fats and oils, fruits, legumes, meat, seafood, sugar, tea, and vegetables were identified. Top candidates for all categories are specific to certain foods, have defined parent compounds, and their concentrations are unaffected by nonfood determinants. The correlations of candidate dietary biomarkers with habitual food intake were moderate to strong and their reproducibility over time ranged from low to high. For many biomarker candidates, critical information regarding dose response, correlation with habitual food intake, and reproducibility over time is yet unknown. The nutritional epidemiology field will benefit from the development of novel methods to combine single biomarkers to generate biomarker panels in combination with self-reported data. The most promising dietary biomarker candidates that reflect commonly consumed foods and food components for application in epidemiological studies were identified, and research required for their full validation was summarized.

Radiographic presentation of artifactual dyed hair on lateral cephalograms, chemical processing, and forensic application: Novel case report

Forensic assessment employs an array of methods to identify human remains. Radiologic examinations with panoramic radiographs, computed tomography scans, Waters view, and nuclear magnetic resonance imaging may offer evidentiary clues in challenging cases, such as mass disasters. In these cases, alternative forensic tools are used to narrow lists of target victims using their biological features. This study aims to I) report on the unusual radiographic aspect of chemicals used for hair dyeing, and II) discuss the potential forensic application of this finding for human identification. The case depicts an asymptomatic 14-years-old female who presented for orthodontic therapy. During radiographic examination on a lateral cephalogram, numerous thin radiopaque streaks were visible, extending to the posterior neck between the occipital region of the skull base and vertebra C6. Clinical investigations revealed that these were artifactual hair images (possibly documented for the first time in the scientific literature). Inductively coupled plasma mass spectrometry (ICP-MS) analysis of the patient's scalp hair was performed for 10 heavy metals, including zinc, copper, iron, chromium, nickel, cadmium, tin, lead, antimony, and bismuth. Eight of these metals were detected at normal levels, ranging from 160 parts per million (ppm) for zinc to less than 1 ppm for nickel, cadmium, tin, lead, and antimony. Conversely, slightly elevated levels of chromium at 0.41 ppm and bismuth at 0.025 ppm were found in the hair sample. The distinctive radiographic presentation of artifactual hair images combined with the chemical properties of hair exposed to dye products may provide useful traces for human identification, especially in mass disasters.

Assessment of Hair Zinc in the School Children in Kayseri, Turkey

Zinc is an essential micronutrient for the organism and is critical for the functional and structural integrity of cells. Determination of the amount of trace element concentrations in tissues such as hair samples have been used for the evaluation of the metabolic status especially in children. Unlike serum zinc, concentrations of zinc in hair are more stable and indicative of variations over time. The purpose of this study is to assess the zinc status of healthy school-age children in Kayseri (Turkey) by measuring the zinc level in hair samples and its association with BMI and the frequency of intake of zinc-rich foods. A total of 527 healthy children, including preadolescent (n = 360) aged 6-10 years and adolescent (n = 167) aged 11-15 years were included in this study. Hair samples were analyzed for zinc content by the inductively coupled plasma-mass spectrophotometry. Analysis of 527 healthy children showed that the mean hair zinc level was 186 ± 77 μg/g. Mean hair zinc level was lower in preadolescent age group than adolescents. There was no significant relationship between the monthly income of the family and the zinc-rich food intake and the zinc level of the hair. Our study shows that samples for analysis of zinc can be obtained with a noninvasive method for determining cases of deficiency during periods of rapid growth. However, further studies are needed to determine the normal tissue zinc level in healthy children, especially in our country and including different geographical regions.

Statistical resolutions for large variabilities in hair mineral analysis

Measuring biomaterials is usually subject to error. Measurement errors are classified into either random errors or biases. Random errors can be well controlled using appropriate statistical methods. But, biases due to unknown, unobserved, or temporary causes, may lead to biased conclusions. This study describes a verification method to examine whether measurement errors are random or not and to determine efficient statistical methods.

A number of studies have dealt with associations between hair minerals and exposures such as health, dietary or environmental conditions. Most review papers, however, emphasize the necessity for validation of hair mineral measurements, since large variations can cause highly variable results. To address these issues, we answer the following questions:

How can we ascertain the reliability of measurements?

How can we assess and control the variability of measurements?

How do we efficiently determine associations between hair minerals and exposures?

How can we concisely present the reference values?

Since hair minerals all have distinctive natures, it would be unproductive to examine each mineral individually to find significant and consistent answers that apply to all minerals. To surmount this difficulty, we used one simple model for all minerals to explore quantitative answers. Hair mineral measurements of six-year-old children were analyzed based on the statistical model. The analysis verified that most of the measurements were reliable, and their inter-individual variations followed two-parameter distributions. These results allow for sophisticated study designs and efficient statistical methods to examine the effects of various kinds of exposures on hair minerals.

Hair geochemical composition of children from Vilnius kindergartens as an indicator of environmental conditions

The research is based on analysis data of Cr, Cu, Mn, Ni, V, Zn (metals) and S in the hair of 47 girls and 63 boys from eight Vilnius kindergartens and the distribution pattern of high metal concentrations and bioavailability in snow-cover dust, also dust samples from vents of characteristic pollution sources. The kindergartens were selected according to topsoil total contamination index and dust-related indices. Significantly higher Cu, Mn, Ni and Zn concentrations in the hair of girls (means are 1.1, 1.9, 1.3, 1.2 times higher) and the differences between hair of genders according to inter-element correlation and clustering were found. Analysis of Spearman correlation coefficients between metal concentrations in hair of each gender and dust metal concentrations or metal loading rates at their residence sites revealed that for Mn, Cu and Zn, they are insignificant, while for Cr, Ni, Pb and V, they are mainly significant positive (except V in female hair). The correlation of the contents of Cr, Ni and V in dust with respective concentrations in hair was more significant for boys (p < 0.001) than for girls. Only a few cases with a significant Cr, Ni, Cu, Pb and Zn increase were revealed in hair of children attending polluted kindergartens in comparison with control. It was concluded that relationship between metal concentrations in hair and dust-related indices is more expressed for children's residence sites than for their kindergarten sites. The gender-based grouping and site-by-site study design are recommended in the studies of reflection of environmental exposure in hair.

Hair Mineral and Trace Element Contents as Reliable Markers of Nutritional Status Compared to Serum Levels of These Elements in Children Newly Diagnosed with Inflammatory Bowel Disease

Patients with inflammatory bowel disease (IBD) are at high risk for nutritional deficiencies because of long-term inflammation in the gut mucosa and decreased oral intake. Because inflammation responses affect serum micronutrient concentrations, serum levels are limited in reflecting body nutrient status in acute and chronic illness. We investigated the usefulness of measuring trace elements in hair as reliable markers of nutritional status compared to serum levels in children with IBD. We retrospectively analyzed pediatric patients newly diagnosed with Crohn's disease (n = 49) and ulcerative colitis (n = 16) and controls (n = 29) from 2012 to 2016. Serum micronutrient levels, inflammatory markers, and hair trace element content were evaluated and compared at the time of diagnosis and before initiating treatment. Serum calcium (p < 0.001), iron (p < 0.001), zinc (p = 0.013), selenium (p = 0.008), albumin (p < 0.001), prealbumin (p < 0.001), hemoglobin and hematocrit (p < 0.001), and WBC (p = 0.001) and lymphocytes (p < 0.001) differed significantly between the groups. After adjustment for the erythrocyte sedimentation rate, serum zinc and selenium levels were no longer significantly different between the groups (p < 0.062 and p < 0.057, respectively). Following hair analysis for mineral and trace elements, iron (p = 0.033), selenium (p = 0.017), and manganese (p = 0.009) differed significantly between the groups. Serum micronutrient levels need cautious interpretation in conjunction with inflammatory markers. Hair mineral and trace element measurement may support understanding micronutrient status in children with IBD.

Sex consideration in diet-biomarker-related indices: a systematic review

OBJECTIVE

An index of biomarkers derived from dietary factors (diet-biomarker-related index) identifies foods and nutrients that encompass physiological potentials and provides scientific evidence for dietary patterns that increase the risk of disease associated with specific biomarkers. Although men and women have different dietary patterns and physiological characteristics, sex is not often considered when investigators develop a diet-biomarker-related index. We aimed to review whether epidemiological studies developed diet-biomarker-related indices in a sex-specific way.

DESIGN

We systematically searched for epidemiological studies that developed diet-biomarker-related indices, including (i) biomarker prediction indices that include dietary factors as explanatory variables and (ii) dietary patterns to explain biomarker variations, in the PubMed and EMBASE databases. We qualitatively reviewed the sex consideration in index development.

RESULTS

We identified seventy-nine studies that developed a diet-biomarker-related index. We found that fifty-four studies included both men and women. Of these fifty-four studies, twenty-nine (53·7 %) did not consider sex, eleven (20·3 %) included sex in the development model, seven (13·0 %) considered sex but did not include sex in the development model, and seven (13·0 %) derived a diet-biomarker-related index for men and women separately. A list of selected dietary factors that explained levels of biomarkers generally differed by sex in the studies that developed a diet-biomarker-related index in a sex-specific way.

CONCLUSIONS

Most studies that included both men and women did not develop the diet-biomarker-related index in a sex-specific way. Further research is needed to identify whether a sex-specific diet-biomarker-related index is more predictive of the disease of interest than an index without sex consideration.

Relationships Between Element Contents in Polish Children's and Adolescents' Hair

Environment, sex, and age are the main factors which determine the elemental composition of hair. The objective of the study is to determine the contents of calcium (Ca), magnesium (Mg), zinc (Zn), copper (Cu), iron (Fe), lead (Pb), and cadmium (Cd) in girls' and boys' hair in five age groups (within 1-19-year range) corresponding to successive human ontogenesis phases as well as to evaluate the relationships between these elements. Quantitative analysis has been carried out using atomic absorption spectrometry (AAS). Experimental results were analyzed using classic and principal component (PCA) statistical analyses. In particular, differences between contents of particularly Ca, Mg, and Zn in girls' and boys' hair were found, and substantial differences between age groups were stated. In general, larger amounts of Ca, Mg, and Zn as compared to boys' hair have been observed for girls' hair and higher toxic element (Pb, Cd) contents for boys were measured in some age groups. An increasing trend was found for bioelements (Ca, Mg, Zn) both for girls and boys in all age groups, while for Cu and Fe content, changes are insignificant and even decreasing for teenagers. The most frequently correlating element pairs are Ca-Mg, Ca-Zn, Mg-Zn, and Pb-Cd. Classic and PCA statistics show, in general, a satisfactory consistence. The elemental composition of hair varies depending on the gender and age of children and young people.

Metal ions released from fixed orthodontic appliance affect hair mineral content

The objective was to evaluate metal ion accumulation in hair of patients undergoing orthodontic treatment with fixed appliances in time. The patients (N = 47) participated in a questionnaire survey. Hair sampling was performed at the beginning and in the 4th, 8th, and 12th month of the treatment. The content of metals (Cr, Ni, Fe) in hair was analyzed by ICP-OES equipped with USN nebulizer. The peak release of Cr and Fe occurred after 4 months of the treatment, and the peak release of Ni gradually increased throughout the whole year of the therapy. During 1 year treatment, an average accumulation of metals in hair tissue was 7.42 ± 14.19 μg of Ni, 8.94 ± 13.1 μg of Cr, and 131 ± 279 μg of Fe. The mean content of Cr was higher than the 90th percentile value for this element. The upper limit of literature reference ranges for Cr, Ni, and Fe in hair was not exceeded. The value of exposure (kinetics and dose) of orthodontic patients to metal ions released from orthodontic appliances can be assessed by hair mineral analysis. The content of Cr was statistically significantly higher during the treatment than before the beginning of therapy.

Biomonitorization of chromium, copper, iron, manganese and nickel in scalp hair from orthodontic patients by atomic absorption spectrometry

The study was aimed to assess Cu, Cr, Fe, Mn and Ni levels in human scalp hair from a broad population group treated with orthodontic appliances (n=70) to determine, whether the concentration of a given metal was significantly influenced by the orthodontic treatment in comparison to control group (n=56). Levels of metal compounds were determined by atomic absorption spectrometry. The mean, ranges, median and 5th and 95th percentiles of metals analyzed in hair that were hypothesized to be systemically absorbed from stainless steel, are provided. The influence of individual factors on metal concentrations was considered (gender, age), and inter-element interactions were studied by evaluation of correlation coefficients between elements, as well as by multiple regression analysis. Differences in the content of metals in hair were only significantly increased for Mn when compared to the control group, but their levels were of the same magnitude to other control populations, and consequently, no risks linked to the treatment have been found. The orthodontic treatment increased significantly Mn levels in young patients (<20 years old) when compared with control group. Scalp hair analysis is a good method to investigate the release of the elements from fixed orthodontic appliances.

Reference values of elements in human hair: a systematic review

BACKGROUND

The lack of systematic review on reference values of elements in human hair with the consideration of methodological approach. The absence of worldwide accepted and implemented universal reference ranges causes that hair mineral analysis has not become yet a reliable and useful method of assessment of nutritional status and exposure of individuals.

OBJECTIVES

Systematic review of reference values of elements in human hair.

DATA SOURCES

PubMed, ISI Web of Knowledge, Scopus.

STUDY ELIGIBILITY CRITERIA

Humans, hair mineral analysis, elements or minerals, reference values, original studies.

RESULTS

The number of studies screened and assessed for eligibility was 52. Eventually, included in the review were 5 papers. The studies report reference ranges for the content of elements in hair: macroelements, microelements, toxic elements and other elements. Reference ranges were elaborated for different populations in the years 2000-2012. The analytical methodology differed, in particular sample preparation, digestion and analysis (ICP-AES, ICP-MS). Consequently, the levels of hair minerals reported as reference values varied.

CONCLUSIONS

It is necessary to elaborate the standard procedures and furtherly validate hair mineral analysis and deliver detailed methodology. Only then it would be possible to provide meaningful reference ranges and take advantage of the potential that lies in Hair Mineral Analysis as a medical diagnostic technique.

Cross-sectional relationship between chronic stress and mineral concentrations in hair of elementary school girls

Chronic stress exposure is associated with diverse negative health outcomes. It has been hypothesised that stress may also negatively affect the body's mineral status. This study investigates the association between chronic stress and long-term mineral concentrations of calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), phosphorus (P) and zinc (Zn) in scalp hair among elementary school girls. Complete information on child-reported stress estimates (Coddington Life Events Scale (CLES)), hair cortisone and hair mineral concentrations, and predefined confounders in the stress-mineral relationship (i.e. age, body mass index, physical activity, diet, hair colour and parental education) was provided cross-sectionally for 140 girls (5-10 years old). The relationship between childhood stress measures (predictor) and hair minerals (outcome) was studied using linear regression analysis, adjusted for the abovementioned confounders. Hair cortisone concentrations were inversely associated with hair mineral concentrations of Ca, Mg, Zn and the Ca/P ratio. Children at risk by life events (CLES) presented an elevated Ca/Mg ratio. These findings were persistent after adjustment for confounders. This study demonstrated an independent association between chronic stress measures and hair mineral levels in young girls, indicating the importance of physiological stress-mineral pathways independently from individual or behavioural factors. Findings need to be confirmed in a more heterogeneous population and on longitudinal basis. The precise mechanisms by which stress alters hair mineral levels should be further elucidated.

Hair minerals and metabolic health in Belgian elementary school girls

Literature has repeatedly shown a relationship between hair minerals and metabolic health, although studies in children are currently lacking. This study aims to investigate hair levels of calcium (Ca), copper (Cu), magnesium (Mg), iron (Fe), phosphorus (P), and zinc (Zn) and their association with (1) overweight/obesity and (2) metabolic health in Flemish elementary school girls between 5 and 10 years old. Two hundred eighteen girls participated in this study as part of the baseline ChiBS project. Children were subjected to physical examinations, blood and hair sampling. Hair minerals were quantitatively determined via inductively coupled plasma-mass spectrometry after microwave-assisted acid digestion. Body mass index (BMI) and body fat percentage (BF%) were studied as anthropometric parameters, and a metabolic score (including systolic and diastolic blood pressure, insulin resistance and non-high-density lipoprotein (non-HDL) cholesterol as parameters) was calculated, with higher scores indicating a more unhealthy metabolic profile. Hair Ca, Ca/Mg, and Ca/P positively correlated with the anthropometric parameters. An inverse correlation was observed between Ca, Mg, and Ca/P in hair and the metabolic score. Inverse correlations were also observed for individual metabolic parameters (i.e., diastolic blood pressure, homeostasis model assessment for insulin resistance, non-HDL cholesterol). In particular, girls with a total number of three or more metabolic parameters above the age-specific 75th percentile showed significantly reduced hair Ca, Mg, and Ca/P concentrations. This study showed reduced hair mineral concentrations in young girls with a more unhealthy metabolic profile. Positive associations were observed between some minerals and BMI and BF%.