Gender as a key factor in trace metal and metalloid content of human scalp hair. A multi-site study

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.

Hair Heavy Metals and Food Consumption in Residents of Chengdu: Factors, Food Contribution, and Health Risk Assessment

Heavy metal pollution is one of the most pressing issues threatening food security and human health. This study assesses heavy metal (chromium, cadmium, copper, zinc, nickel, and lead) exposure via hair metal concentrations in Chengdu residents, reflecting metal intake from food consumption. From June 2020 to February 2021, a sampling survey was conducted on residents' hair (n=182) and food (n=301) in six main urban areas of Chengdu. The concentrations of heavy metals in hair and food were analyzed by inductively coupled plasma mass spectrometry, and the results showed that the residents of Chengdu City had high hair concentrations of Cd (0.17±0.03 mg kg-1) and Zn (293±21.3 mg kg-1). Gender significantly affected the hair Cr, Zn, and Ni concentrations. Based on the survey results obtained from Chengdu City residents, the habits and diet structure are assessed for the influence of six heavy metals in the hair of the residents. Adolescents' (13-18 years old) hair had significantly higher Pb concentrations than adults (19-59 years old). The concentration of Ni in hair was affected by perming and dyeing habits. For dietary exposure, cereals and meat were the main contributors to the residents' daily intake of heavy metals. The bioaccessibility of Cr, Cd, Cu, Zn, Ni, and Pb in food was 2.45-74.67%, 10.6-78.7%, 13.4-82.5%, 8.89-89.2%, 7.70-85.1%, and 15.4-86.2%, respectively. In health risk evaluation based on the bioaccessible fraction of six heavy metals, the hazard quotient of each heavy metal in food was less than 1, indicating no potential non-carcinogenic risk.

Spatial distribution, impact factors, and potential health implications of trace elements in human hair from capital residents in China

We analyzed the levels, spatial distribution, impact factors, source apportionment, and potential health implications of trace elements (V, Zn, Cu, Mn, Ni, Mo, and Co) in 1202 human hair samples of urban residents aged 4-55 from 29 cities in China. The median values of seven trace elements in hair were found in the following increasing order: Co (0.02 μg/g) < V (0.04 μg/g) < Mo (0.05 μg/g) < Ni (0.32 μg/g) < Mn (0.74 μg/g) < Cu (9.63 μg/g) < Zn (157 μg/g). The spatial distribution of these trace elements in the hair from the six geographical subdivisions varied depending on the exposure sources and impact factors. Principal component analysis (PCA) revealed that Cu, Zn, and Co in the hair samples of urban residents were primarily derived from food, whereas V, Ni, and Mn were attributed to industrial activities and food. Majority of the hair samples (up to 81%) from North China (NC) exceeded the recommended value for V content, whereas up to 59.2%, 51.3%, and 31.6% samples from Northeast China (NE) exceeded the recommended values for Co, Mn, and Ni contents, respectively. The levels of Mn, Co, Ni, Cu, and Zn were significantly higher in female hair than those in male hair, whereas the levels of Mo were higher in male than in female hair (p < 0.01). Furthermore, significantly higher Cu/Zn ratios were observed in the hair of male residents than those in the female residents (p < 0.001), indicating a higher health risk for male residents.

Potentially toxic elements in human scalp hair around China's largest polymetallic rare earth ore mining and smelting area

There is a growing concern about human health of residents living in areas where mining and smelting occur. In order to understand the exposure to the potentially toxic elements (PTEs), we here identify and examine the cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn) in scalp hair of residents living in the mining area (Bayan Obo, n = 76), smelting area (Baotou, n = 57) and a reference area (Hohhot, n = 61). In total, 194 hair samples were collected from the volunteers (men = 87, women = 107) aged 5-77 years old in the three areas. Comparing median PTEs levels between the young and adults, Ni levels were significantly higher in adults living in the smelting area while Cr was highest in adults from the mining area, no significant difference was found for any of the elements in the reference area. From the linear regression model, no significant relationship between PTEs concentration, log₁₀(PTEs), and age was found. The concentrations of Ni, Cd, and Pb in hair were significantly lower in the reference area when compared to both mining and smelting areas. In addition, Cu was significantly higher in the mining area when compared to the smelting area. Factor analysis (FA) indicated that men and women from the smelting area (Baotou) and mining area (Bayan Obo), respectively, had different underlying communality of log10(PTEs), suggesting different sources of these PTEs. Multiple factor analysis quantilized the importance of gender and location when combined with PTEs levels in human hair. The results of this study indicate that people living in mining and/or smelting areas have significantly higher PTEs (Cu, Ni, Cd, and Pb) hair levels compared to reference areas, which may cause adverse health effects. Remediation should therefore be implemented to improve the health of local residents in the mining and smelting areas.

Selenium and toxic metals in human hair of the Dashan Region, China: Concentrations, sources, and antagonism effect

The Dashan Region was a Se-rich region of China. In this study, 131 residents' human hair samples were collected. The concentrations of Se and toxic metals were analyzed, and the health risk was estimated using the concentration data. Cd and As concentrations were significantly higher than in East China. Se and most toxic metal concentrations increased with age (except for the aged people). Furthermore, gender and smoking habits might have a significant impact on toxic metals and Se levels. Multivariable statistics analysis revealed that Se and toxic metals primarily originate in the environment and are then transferred to the human body via the food chain. Dietary habits had an effect on the Se and As concentrations in hair, according to the results of stable isotope analysis. To assess detoxification ability, the Se/ toxic metal molar ratio was used as an indicator. The results demonstrated that the antagonistic effect of Se and Cd, As, Cr, and Hg (molar ratio > 1) could effectively protect residents in the study area from Cd and As pollution in daily life.

Levels of trace elements in human hair samples of adolescents living near petrochemical plants

The aim of the study is a comparative analysis to investigate human hair metal profiles of adolescents residing near petrochemical plants (Sicily, Italy). We selected the small town of Augusta, Gela, and Pace del Mela, and a control area made up of the towns characterized by low anthropogenic activity. Twenty trace elements were measured in samples of scalp hair from adolescents (11-14 years old) of both genders. Hair samples were cleaned using a rigorous cleaning method, mineralized, and processed for analyses by inductively coupled plasma-mass spectrometry (ICP-MS). In industrial sites, zinc was always the most abundant element, ranging from186 to 217 μg g^-1. Following zinc, the elements Al, Ba, Cu, Fe, and Sr were in the range 1-20 μg g^-1. The remaining elements had concentrations < 1 μg g^-1. The comparison with adolescents living in suburban area highlighted that As, Ba, Mn, Sr, U, and V have the highest median concentrations in an industrial location. An industrial factor (As, Mn, Sr, U, and V) and an urban factor (Cd, Cr, Cu, Mo, Ni, and Sb) were distinguished by the multivariate statistical analysis between a cohort residing in urban and industrial areas. Statistically significant differences (Kruskal-Wallis test, p < 0.05) between the genders were found for Ba, Mn, Ni, Sr, and V in all industrial sites with median concentrations higher in females' hair than males'. The data confirm that the study areas are heavily affected by industrial and urban emissions of metals and metalloids, representing a potential hazard to the local population.

High manganese and nickel concentrations in human hair and well water and low calcium concentration in blood serum in a pristine area with sulphide-rich bedrock

We report the trace element status of residents living in areas with naturally sulphide-rich bedrock and soil in two municipalities in Finland, Sotkamo and Kaavi. Altogether, 225 people from these sparsely populated regions participated voluntarily by providing hair and blood samples. The concentrations of calcium, zinc and copper in serum as well as selenium and cadmium in whole blood did not show correlation with those concentrations in hair samples. Calcium concentration in serum was slightly lower in the sulphide-rich areas (median value 91.4 mg/l, n = 103) than in the areas with adjacent sulphur-poor bedrock (median value 93.6 mg/l, n = 82). The concentrations of Ni and Mn in hair correlated with those in drinking water. The highest Mn and Ni concentrations in the water samples from private wells were 1620 µg/l and 51 µg/l and the highest concentrations in human hair samples 36.44 mg/kg and 12.3 mg/kg, respectively. The challenge with elevated trace element concentrations in some well waters is well documented. In northern countries (Finland, Sweden, Norway and Canada), only 10% of the population depend on private well water, and 90% have access to monitored municipal water supplies. Compared with data available from sulphide mine sites globally, the nickel and manganese concentrations in human hair samples were high in our sulphide-rich study area at Sotkamo representing the trace element status of residents under natural conditions.

Person identification using the composition of elements in human hair

If an individual cannot be identified, it is necessary to conduct a forensic medical examination. In this case, all possible group indexes are investigated. In this study, the content of elements in hair was investigated to identify individuals by territory, age, profession, or gender. The level of 14 micro- and macroelements (Cu, Zn, Co, Fe, Cr, Mn, Cd, As, Pb, Ni, P, Ca, K and Mg) was determined in hair samples of men and women from five age categories (21 to >60) using inductively coupled plasma atomic emission spectroscopy. The samples were analyzed taking into account the health condition, gender, place of residence, occupation, work experience, and age. A correlation between the content of elements in people's hair and their place of residence was observed. The difference in the content of elements in the hair of urban and rural residents was substantial and statistically significant (p<0.05). Moreover, there were significant differences related to age (p<0.0051) and gender (p<0.05). The current research detected significant differences in the content of the chemical elements in the hair of the groups tested, which can be used as personal identification indicators depending on occupation, work experience, and environmental factors.

Multi-matrix biomonitoring approach to assess exposure to metals and trace elements in the Lebanese population and associations with drinking water consumption

This study is the first attempt to assess exposure to metals and trace elements in subgroups of the Lebanese population using a multi-matrix biomonitoring approach. Concentrations of 11 metals and trace elements (aluminum (Al), arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), selenium (Se), uranium (U), zinc (Zn)) were measured in urine, hair and toenails. Biological levels were compared according to age, sex, smoking status, socioeconomic status, geographical area and drinking water source. While most urinary and toenail concentrations of metals and trace elements were not different between males and females, measured concentrations of several elements in hair were higher in females compared to males. Urinary concentrations of some metals (Al, Cu, Se and Zn) were higher in children compared to teenagers and adults. Hair and toenail concentrations of several elements (As, Cd, Pb, Mn, Se in hair and toenails plus Al, Fe in toenails) were also significantly higher in children compared to teenagers and/or adults. Smoking status had no influence on metal and trace element concentrations. Levels of Cd, Pb and Mn were also higher in samples from subgroups with lower economic status (Cd and Pb in the three matrices and Mn in hair and toenails). Very few correlations were identified between sources of drinking water and urine, hair, and toenail concentrations of metals and trace elements. However, a correlation was observed between hair and toenails levels of As, Cd and Pb. Overall, results highlight that a special attention should be given to metal and trace element exposure in this population (including Pb, As, Cd, Mn, and Se). It could be relevant to scale up this kind of investigation with a large human biomonitoring initiative in the Lebanese population in order to generalize results, and assess trends over time.

Hair Toxic Trace Elements of Residents across the Caspian Oil and Gas Region of Kazakhstan: Cross-Sectional Study

This study aimed to assess the relationship between the content of toxic trace elements, such as aluminum (Al), arsenic (As), beryllium (Be), cadmium (Cd), mercury (Hg), and lead (Pb), in the hair of the adult population of western Kazakhstan and the distance of their residence from oil and gas fields. The cross-sectional study included 850 adults aged 18-60 years. Inductively coupled plasma mass spectrometry was used to measure the level of Al, As, Be, Cd, Hg, and Pb in hair. The relationship between the concentration of toxic trace elements in the hair and the distance from oil and gas fields was assessed in three groups (<16 km, 16-110 km, and >110 km), using multiple linear regression analysis. The highest concentration of Hg = 0.338 μg/g was determined in the group living near oil and gas fields (0-16 km), whereas the lowest concentration of Al = 3.127 μg/g and As = 0.028 μg/g was determined in participants living at a long distance (more than 110 km) (p < 0.001). The concentration of Al (-0.126 (CI: -0.174; -0.077)), Hg (-0.065 (CI: -0.129; -0.001)), and Pb (0.111 (CI: 0.045; 0.177)) is associated with the distance to oil and gas fields. The obtained data indicate a change in the toxic trace element content in the hair of residents in the Caspian region of western Kazakhstan, a change that is most pronounced in residents living in the zone of oil and gas pollution. The distance to the oil and gas fields affects the content of toxic elements in scalp hair. In particular, the concentration of Al and Hg is associated with a decrease in the distance to oil and gas fields, while the concentration of Pb is associated with an increase in the distance to these fields. The lowest content of Al and As was determined in the hair of study participants living in the most remote areas (more than 110 km from oil and gas fields). Our results demonstrate the need for the biomonitoring of toxic elements to determine long-term temporal trends in the impact of chemicals on public health in western Kazakhstan.

Associations of exposure to metal and metal mixtures with thyroid hormones: Results from the NHANES 2007-2012

BACKGROUND

Disrupted thyroid homeostasis plays a role in neurocognitive dysfunction and metabolic disorders. Since individuals are exposed to multiple metals simultaneously, it is important to assess the effects of metal mixtures on thyroid hormone status. This study aimed to investigate the associations of metal mixtures and individual metals with thyroid hormone levels.

METHODS

Data included 2399 men and 1988 women from the 2007-2012 National Health and Nutrition Examination Survey (2007-2012). Thyroid hormones measured included total triiodothyronine (T3), total thyroxine (T4), free forms of T3 (FT3) and T4 (FT4), and thyroid stimulating hormone (TSH). We included twelve metals (arsenic, barium, cobalt, cesium, molybdenum, antimony, thallium, tungsten, and uranium from urine; cadmium, lead, and mercury from blood) in traditional linear regression models controlling for 12 metals simultaneously and in quantile-based g-computation (QGC) to assess the relative contribution of each metal as well as the overall association with thyroid hormones as a metal mixture.

RESULTS

There were associations of the total metal mixture with thyroid hormones for T3 (beta: -0.023, 95% CI: -0.04, -0.01, in women), T4 (beta: -0.03, 95% CI: -0.05, -0.01, in men; beta: -0.026, 95% CI: -0.04, -0.01, in women), and the T3:T4 ratio (beta: 0.026, 95% CI: 0.01, 0.05, in men). Arsenic had negative contributions to T3 and T4. Cadmium had a positive contribution to T4 but negative contributions to T3 and T3:T4. Lead had a positive contribution to T3 and T3:T4, but a negative contribution to T4.

CONCLUSION

Multiple metals as a mixture were associated with thyroid hormone levels. Arsenic, cadmium, and lead were individually associated with multiple thyroid hormones. Examination of associations of metal mixtures and individual metals with thyroid hormones can contribute to an understanding of thyroid hormone homeostasis and provide evidence for developing intervention and guidance for health promotion.

Assessing oxidative stress resulting from environmental exposure to metals (Oids) in a middle Eastern population

Concentrations of metals and metalloids derived mainly from anthropogenic activities have increased considerably in the environment. Metals might be associated with increase reactive oxygen species (ROS) damage, potentially related to several health outcomes. This study has recruited 200 adult participants, including 110 males and 90 females in Shiraz (Iran), to investigate the relationship between chronic exposure to metals and ROS damage by analyzing malondialdehyde (MDA) and 8-Oxo-2'-deoxyguanosine (8-OHdG) concentrations, and has evaluated the associations between chronic metal exposure and ROS damage using regression analysis. Our findings showed participants are chronically exposed to elevate As, Ni, Hg, and Pb levels. The mean urinary concentrations of 8-OHdG and MDA were 3.8 ± 2.35 and 214 ± 134 µg/g creatinine, respectively. This study shows that most heavy metals are correlated with urinary ROS biomarkers (R ranges 0.19 to 0.64). In addition, regression analysis accounting for other confounding factors such as sex, age, smoking status, and teeth filling with amalgam highlights that Al, Cu, Si and Sn are associated with 8-OHdG concentrations, while an association between Cr and MDA and 8-OHdG is suggested. Smoking cigarettes and water-pipe is considered a significant contributory factor for both ROS biomarkers (MDA and 8-OHdG).

Essential Trace Elements in Scalp Hair of Residents across the Caspian Oil and Gas Region of Kazakhstan

Most of the country’s oil and gas fields are situated in West Kazakhstan, mainly on the Caspian Sea coast, causing significant damage to the local environment and contributing to an imbalance in the trace element composition of the human body. The study is aimed to evaluate the relationship between the concentration of essential trace elements in scalp hair of the western Kazakhstan adult population and the remoteness of their residence from oil and gas fields. The concentration of essential trace elements (Co, Cu, Fe, I, Mn, Se, Zn) in the hair of 850 individuals aged 18−60 years was determined by inductively coupled plasma mass spectrometry. In residents of settlements located at a distance of >110 km from oil and gas fields, the concentration of Cu and I in hair was significantly higher than in those closer to 110 km (p < 0.001). The content of Cu and I were associated with the distance to oil and gas fields (0.072 (95% CI: 0.050; 0.094)) and (0.121 (95% CI: 0.058; 0.185)), respectively. We detected a significant imbalance in the distribution of some essential trace elements in residents’ scalp hair from the Caspian region of western Kazakhstan, living near oil and gas fields. The concentrations of Cu and I were significantly interrelated with the distance to oil and gas fields. The level of copper in the hair of both inhabitants of the area most remote from oil and gas facilities and the entire population of western Kazakhstan as a whole remains significantly low. The data obtained provide evidence of the possible impact of pollutants generated by the oil and gas facilities on a shortage of essential trace elements and associated subsequent health risks.

Sex-specific associations of exposure to metal mixtures with telomere length change: Results from an 8-year longitudinal study

Studies on the relationships between exposure to metal mixtures and telomere length (TL) are limited, particularly longitudinal studies. Few studies are available on the potential sex-specific associations between metal exposures and TL change. We examined blood metal concentrations and TL at baseline (August 2012) and follow-up (June 2020) among 316 participants in a ferro-manganese refinery. The least absolute shrinkage and selection operator (LASSO) followed by the generalized linear model (GLM) was applied to evaluate the associations between multiple-metal exposures and TL change (TL in 2012 minus TL in 2020). Bayesian kernel machine regression (BKMR) was applied to cope with metal mixtures and evaluate their joint effects on TL change. Among men, three statistical methods consistently showed rubidium was negatively associated with TL change (β [95% CI] = -2.755 [-5.119, -0.391] in the GLM) and dominated the negative overall effects of 10 metal mixtures (magnesium, manganese, iron, cobalt, copper, zinc, selenium, rubidium, cadmium, and lead) on TL change (posterior inclusion probabilities = 0.816). Among women, the GLM (β [95% CI] = 4.463 [0.943, 7.983]) and LASSO (β = 4.289) showed rubidium was positively associated with TL change. Interestingly, no significant association was observed between exposure to metal mixtures and TL change in overall participants (P > 0.05). Furthermore, stratified analysis showed significant relationships between rubidium and TL change in men (β = -2.744), women (β = 3.624), and current smokers (β = -3.266) (both P interaction <0.05). In summary, our findings underlined the steady and negative association between rubidium and TL change among men with potential sex-dependent heterogeneities. Further experimental studies are required to expound the underlying mechanisms.

Heavy Metal in Rice and Vegetable and Human Exposure near a Large Pb/Zn Smelter in Central China

Non-ferrous metal smelting is a significant source of anthropogenic heavy metal emission and has led to severe environmental pollution that ultimately threatens the health of local residents. In this study, we determined concentrations of copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb), as well as Pb isotopic compositions in rice, vegetables and human hair in areas surrounding the Zhuzhou Pb/Zn smelter in Hunan, China and we assessed the health risks associated with rice and vegetable consumption for local residents. Results showed that rice and vegetable samples were significantly contaminated by Cd and Pb. Age and source of rice were important factors for the enrichment of heavy metal concentrations in human hair. The ratios of Pb isotopes in human hair (1.164-1.170 for ²⁰⁶Pb/²⁰⁷Pb and 2.102-2.110 for²⁰⁸Pb/²⁰⁶Pb) were comparable to those in rice (1.162-1.172 for ²⁰⁶Pb/²⁰⁷Pb and 2.098-2.114 for²⁰⁸Pb/²⁰⁶Pb) and were slightly lower than those in vegetables (1.168-1.172 for ²⁰⁶Pb/²⁰⁷Pb and 2.109-2.111 for²⁰⁸Pb/²⁰⁶Pb), indicating that Pb in human hair mainly originated from food ingestion. A non-carcinogenic risk assessment showed that Cd exposure was the dominant health risk for local residents. This study suggested that crops planted surrounding the smelter were seriously contaminated with Cd and human exposure was related to dietary intake.

Diet and dog characteristics affect major and trace elements in hair and blood of healthy dogs

Obtaining correct amounts of essential elements, and avoiding toxic metals are key factors in dog health. Through analyzing major and trace elements in hair and blood of 50 healthy companion dogs using ICP-MS, we study their associations with dog characteristics and diet, hypothesizing that eating the same diet long-term results in strong correlations between hair and blood element concentrations, and that dog characteristics and diet affect element status. The correlation between hair and blood was significant for Hg (R = 0.601, p = 0.000) and Pb (R = 0.384, p = 0.010). The following associations were significant (p < 0.05): Dark hair had higher Ca and Mg compared to light hair. Females had higher hair Zn, blood Mn, and blood As compared to males. Blood Mn and Se increased, while blood Pb decreased with age. Raw diet fed dogs had higher hair Zn and Se compared to dry or mixed diet fed dogs, and lower blood Mn compared to dry diet fed dogs. Dry and mixed diet fed dogs had higher blood Cd compared to raw diet fed dogs. Mixed diet fed dogs had higher hair Ca and Mg compared to raw or dry diet fed dogs, and higher hair Pb compared to dry diet fed dogs. Wild game consumption was associated with higher blood Pb, and rice consumption with higher blood As. In conclusion, hair provides an alternative for assessing Hg and Pb exposure, and major and trace elements status is affected by hair color, sex, age, and diet.

Assessing the Causal Role of Selenium in Amyotrophic Lateral Sclerosis: A Mendelian Randomization Study

Objectives: The relation between selenium overexposure and increased risk of amyotrophic lateral sclerosis (ALS) has been subject to considerable interest. Epidemiologic studies have reported suggestive associations between selenium and ALS, although the causal inference between selenium and ALS remains to be established.

Methods: We conducted a two-sample Mendelian randomization (MR) analysis to analyze the causal role of selenium on ALS risk. Variants associated with selenium levels were obtained from the GWAS meta-analysis of circulating selenium levels (n = 5,477) and toenail selenium levels (n = 4,162) in the European population. Outcome data were from the largest ALS GWAS dataset with 20,806 ALS cases and 59,804 controls in the European population. Inverse variance weighted (IVW) method was used as the main analysis, with an array of sensitivity analyses performed to detect potential violations of MR assumptions.

Results: Inverse variance weighted (IVW) analysis indicated no evidence of a causal role for selenium levels in ALS development (odds ratio (OR) = 1.02, 95% confidence interval (CI) = 0.96–1.08). Similar results were observed for the sensitivity analyses (OR = 1.00, 95% CI = 0.95–1.07 for weighted median; OR = 1.07, 95% CI = 0.87–1.32 for MR-Egger), with no pleiotropy detected.

Conclusions: Although selenium was found associated with ALS according to earlier epidemiologic studies, current evidence based on the population of European ancestry does not support the causal effect of selenium on ALS risk.

Current applications and future perspectives on elemental analysis of non-invasive samples for human biomonitoring

Humans are continuously exposed to numerous environmental pollutants including potentially toxic elements. Essential elements play an important role in human health. Abnormal elemental levels in the body, in different forms that existed, have been reported to be correlated with different diseases and environmental exposure. Blood is the conventional biological sample used in human biomonitoring. However, blood samples can only reflect short-term exposure and require invasive sampling, which poses infection risk to individuals. In recent years, the number of research evaluating the effectiveness of non-invasive samples (hair, nails, urine, meconium, breast milk, placenta, cord blood, saliva and teeth) for human biomonitoring is increasing. These samples can be collected easily and provide extra information in addition to blood analysis. Yet, the correlation between the elemental concentration in non-invasive samples and in blood is not well established, which hinders the application of those samples in routine human biomonitoring. This review aims at providing a fundamental overview of analytical methods of non-invasive samples in human biomonitoring. The content covers the sample collection and pretreatment, sample preparation and instrumental analysis. The technical discussions are separated into solution analysis and solid analysis. In the last section, the authors highlight some of the perspectives on the future of elemental analysis in human biomonitoring.

Elemental composition of hair as a marker for forensic human identification

BACKGROUND

Hair is one of the most common evidence types found in criminal investigations. Analysis of human hair reveals the mineral composition accumulated within it over time spent in a specific area, thereby providing additional information for forensic identification.

MATERIALS AND METHODS

To identify patterns of the elemental composition of hair in territories with different natural and anthropogenic features, hair samples of 1238 residents and 217 corpses of Central Kazakhstan were studied. The determination of 14 chemical elements in hair by inductively coupled plasma atomic emission spectrometry were presented. The data were analysed in terms of place of residence, gender, age and condition.

RESULTS

The results showed that the concentration of trace elements like Cu, Fe, Cd, and As significantly differed among all regions (p < 0.05). The composition of hair samples obtained from women significantly differed from those obtained from men for certain major and trace elements (p < 0.05). Concentrations of Ca and Mg in men were significantly lower than in women (p < 0.05) and were decreasing with age (p < 0.05).

CONCLUSIONS

The present investigation revealed a relationship between the elemental composition of hair and the place of permanent residence of a person, formed under the influence of regional industrial complexes, and determining gender and age-related differences. These findings enhance the possibilities of forensic human identification.

Levels of major and trace metals in the scalp hair of Crohn's disease patients: correlations among transition metals

Concentrations of 16 metals in the scalp hair of male Crohn's disease (CD) patients (n = 28) were compared to those of male control subjects (n = 25). The majority of patients (n = 20) took an anti-inflammatory agent (mesalazine), and several patients underwent colectomy. A low concentration of serum ferritin was observed in approximately 50% of CD patients due to Fe-deficiency anemia. The concentrations of Fe, Cr, and Co in the hair of CD patients were significantly higher than those of control subjects, and particularly high concentrations were found in CD patients with low serum ferritin. Significant correlations were found among the concentrations of Fe, Cr, and Co in the hair of CD patients, but not in control subjects. In agreement with previous reports, a significant negative correlation was found between ferritin and transferrin concentrations in serum, although the available data in this study was limited (n = 8). Transferrin not only binds to Fe³⁺ but also to Cr³⁺ and Co³⁺, and the amount of transferrin is increased in Fe-deficiency anemia. Thus, the majority of the Fe³⁺, Cr³⁺, and Co³⁺ in the serum of CD patients is likely to bind to transferrin, which may be associated with the higher concentrations of those metals, as well as the significant correlations among those metals in the scalp hair of CD patients. In addition, colectomy may alter the intestinal absorption rate of some metals, while mesalazine may increase the concentrations of Mn and some metals in the scalp hair by chelate formation.

Element Levels and Predictors of Exposure in the Hair of Ethiopian Children

Children's development and health may be affected by toxic heavy metal exposure or suboptimal essential element intake. This study aimed to provide updated information regarding the concentrations of 41 elements in children's hair (aged under 18) living in a rural area of the Benishangul-Gumuz region, Ethiopia. The highest average levels (as a geometric mean) for toxic heavy metals were obtained for Al (1 mg kg^-1), Pb (3.1 mg kg^-1), and Ni (1.2 mg kg^-1), while the lowest concentrations among the essential elements were found for Co (0.32 mg kg^-1), Mo (0.07 mg kg^-1), Se (0.19 mg kg^-1), and V (0.8 mg kg^-1). Hair analysis was combined with a survey to evaluate relationships and variations among subgroups and potential metal exposure predictors. Females showed significantly higher concentrations for most hair elements, excluding Zn, than males, and the 6-11 years age group reported the highest levels for Be, Ce, Co, Fe, La, Li, Mo, and Na. The main predictors of exposure to toxic elements were fish consumption for Hg and drinking water for Ba, Be, Cs, Li, Ni, Tl, and U. The data from this study can be used to develop prevention strategies for children's health and protection in developing countries.

Occupational Exposure Assessment of Major and Trace Elements in Human Scalp Hair Among a Group of Eritrean Workers

The aim of the study was to evaluate occupational exposure to 40 elements among a group of Eritrean adults employed at the Medeber metal market by analysing human scalp hair samples and by investigating the role of some predictors (gender, age, and body mass index-BMI) on their levels. Scalp hair samples were collected from 60 subjects (32 subjects working at the Medeber metal market and 28 subjects not working at Medeber and not employed in other industrial or artisanal activities) and were analysed through inductively coupled plasma mass spectrometry to determine the contents of 40 major and trace elements. Information on participants was collected via questionnaire. Significant differences were found in the hair levels of certain elements between subjects working at the Medeber metal market and subjects not exposed. In particular, working at the Medeber metal market increased hair levels of Be, B, Cu, Zn, Mo, Cd, Sb, Tl, Pb, and Fe from 25 to 100%, while reduced Na, K, and Rb levels from 30 to 50%. With multivariate adjustment for age, gender, and BMI, the results confirm that working at Medeber significantly increased the hair levels of Cu, Zn, Sb, Pb, and Fe. This finding reveals the need for more accurate and routine biomonitoring surveys and the necessity of health promotion campaigns both for local decision-makers and workers to increase health promotion and safety in this workplace.

Exposure to polycyclic aromatic hydrocarbons (PAHs) in people living in urban and rural areas as revealed by hair analysis

Some polycyclic aromatic hydrocarbons (PAHs) are carcinogenic and mutagenic to humans. However, little is known about PAH exposure to people living in urban and suburban areas through comparative studies. Some studies have indicated that human hair can be used as a noninvasive biomarker of PAH exposure. Therefore, we collected hair samples from 66 volunteers from Nanjing and Ningbo, China, to detect PAH concentrations in this work. The highest levels in the hair samples were found in phenanthrene > anthracene > naphthalene among the parent PAHs. Sixteen parent PAHs showed higher concentrations in the samples from Nanjing than in the samples from Ningbo. Significantly higher levels of some PAHs were observed in male hair than in female hair in Nanjing, and in hair from smokers than in hair from non-smokers in both Nanjing and Ningbo. In addition, there was a significant effect of the age on the concentration of low-molecular-weight PAHs and ∑PAHs in human hair in both Nanjing and Ningbo. Studying the inter-chemical associations between these PAHs indicated similarities and differences between Nanjing and Ningbo.

Environmental chronic exposure to metals and effects on attention and executive function in the general population

Heavy metals are neurotoxic, associated with brain dysfunction, and have been linked with cognitive decline in adults. This study was aimed to characterize chronic exposure to metals (Cd, Be, Co, Hg, Sn, V, Al, Ba, Cr, Cu, Fe, Li, Mn, Ni, Pb, and Zn) and metalloids (As, B, Sb) and assess its impact on cognitive performance of Tehran's residents, capital of Iran. Scalp hair samples gathered from 200 volunteered participants (110 men and 90 women), aged 14-70 years and quantified by inductively coupled plasma atomic emission spectroscopy (ICP-OES). Attention and executive function, two measures of cognitive performance, were characterized using the trail making test (TMT) part A and B, respectively. Mental flexibility was characterized as the Delta TMT B-A scores and cognitive efficiency or dissimulation as the ration between TMT B and A scores. A comprehensive questionnaire was used to gather information on demographic and socioeconomic as well as lifestyle and health status. The highest and lowest mean concentrations were observed for B (325 μg/g) and As (0.29 μg/g), respectively. Results indicated that chronic metal exposure measured in hair changed significantly based on gender and age (p < 0.05). The levels of Cr, Fe, Ni, Si, Hg, Pb and B were significantly higher in males' hair, whereas those of Ag and Ba were greater in females' hair (p < 0.05). The results of the cognitive TMT test were significantly different between gender and age groups (p < 0.05). Moreover, results revealed that As, Hg, Mn, and Pb levels in hair were significantly associated with poorer participants' performance scores in the TMT test (p < 0.05). Age, gender, cigarette smoking, water-pipe smoking, traffic density in the area of residence, and dental amalgam filling were significant factors affecting the TMT test scores. The results suggest that chronic exposure to metals has detrimental effects on attention, executive function, mental flexibility and cognitive efficiency.

Age- and sex-dependence of five major elements in the development of human scalp hair

Background

Human scalp hair is composed of bio-synthesized protein that stores and excretes excess elements from the body. Thus, the concentration of major and trace elements in the hair may provide insight into both the physiology and health status of humans. Monitoring of health status by hair analysis is limited by the uncertainty surrounding natural changes in composition based on age and sex parameters.

Methods

A total of 322 hair samples from subjects aged 0–89 years were collected and analyzed to determine their sulfur, calcium, magnesium, zinc, and copper concentrations by inductively coupled plasma mass spectrometry. The age- and sex-dependence of the concentrations of these elements within scalp hair was evaluated. Age-dependence was analyzed by least squares fitting of the data from young people (up to 25 years old). Sex-dependence was evaluated by comparing the average element concentrations of males and females in each age groups.

Results

The concentration of mineral elements increased with age up to 25 years old. Calcium and magnesium contents were strongly affected by age, whereas the effects were weaker for zinc and copper. In participants over 20 years old, sex and the concentrations of calcium and magnesium were significantly associated. The concentrations of these elements were higher in most of the subgroups of adult women. The concentrations of sulfur, zinc, and copper were not significantly associated with age or sex.

Conclusions

The concentrations of major inorganic elements in scalp hair showed an increasing trend up to 25 years of age, and a strong sex dependence of calcium and magnesium concentrations in the subjects older than 20 years. More research is needed to understand the physiology of calcium and magnesium excretion though scalp hair.

Biomonitoring of Trace Elements in Hair of Schoolchildren Living Near a Hazardous Waste Incinerator-A 20 Years Follow-Up

Since 1998, a monitoring program is periodically performed to assess the environmental and human health impact of air chemicals potentially emitted by a hazardous waste incinerator (HWI) located in Constantí (Catalonia, Spain). In 2017, samples of hair were collected from 94 schoolchildren (aged 10-13 years) living nearby and the levels of 11 trace elements (As, Be, Cd, Cr, Hg, Mn, Ni, Pb, Sn, Tl and V) were determined. The concentrations showed the following descending order: Pb > Hg > Ni > Sn > Mn > Cr. In turn, As, Be and Tl were not detected, while Cd and V were found only in a few samples. Some metal levels were significantly, positively correlated. Some significant differences were also noticed according to the gender and the specific zone of residence. Finally, the levels of trace elements showed fluctuations through time. Cr and Pb showed a significant decrease in comparison to the concentrations obtained in the baseline study (1998). According to the current results, metal emissions from the HWI are not relevant in terms of human health impact since their levels were similar and even lower than those reported in other contaminated areas.

Hair Trace Element Levels in Han and Indigenous Hualien Inhabitants in Taiwan

The objective of the present study was to assess the impact of ethnicity on hair trace element content in Han and aboriginal inhabitants of Hualien in Taiwan. Fifty Han (female/male = 35/15) and 50 aboriginal (female/male = 40/10) Hualien inhabitants aged 40-60 years were involved in the present study. Anthropometric data and dietary patterns were recorded. Hair mineral, essential, and toxic trace element levels were assessed using inductively coupled plasma mass spectrometry at NexION 300D (PerkinElmer Inc., USA) equipped with ESI SC-2 DX4 autosampler (Elemental Scientific Inc., USA). No group difference in gender, age, body weight, height, or physical activity was observed. Fish intake was more frequent in Han inhabitants, whereas aborigines consumed significantly more nuts. Indigenous people were characterized by higher hair Al (45%), Ca (threefold), Co (71%), Fe (twofold), I (74%), K (60%), Mg (2.5-fold), Na (62%), P (6%), Sn (78%), and V (46%) content. In turn, Han Hualien inhabitants had higher hair Be (twofold), Li, Se, Si levels as compared to indigenous counterparts. Multiple regression analysis demonstrated that ethnicity was significantly associated with hair Ca (β = 0.302), Mn (β = 0.284), P (β = 0.387), and Se (β = - 0.310) levels after adjustment for other confounders. At the same time, the overall models were significant for Ca, Mn, Se, and As. The obtained data may provide a background for monitoring and correction of trace element status in patients of different ethnic groups. However, further detailed studies are required to highlight the mechanisms underlying the observed associations.

Distribution characteristics and influencing factors of heavy metals in scalp hair of Huainan urban residents

In order to explore the level of heavy metal pollution in human hair of residents in Huainan City and provide theoretical guidance for prevention and control of heavy metal pollution, human hair samples from 174 residents in Huainan City were collected so that heavy metal (Cr, Cu, Pb, Zn, As, and Fe) concentrations in scalp hair could be tested, and meanwhile their relationship with sex, age, and spatial distribution characteristics could be explored as well. According to the final analysis, the average concentration of Cr, Pb, Cu, Fe, Zn, and As in human hair amounted to 1.56, 6.41, 14.96, 31.13, 166.54, and 1.07 mg/kg. The highest average of Cr and Pb contents in human hair occurred in the area of Xiejiaji District; Fe, Zn, and Hg were in Datong District; and Cu and As were in Panji District respectively. Overall, the lowest risk of heavy metal exposure existed in Tianjia'an District. Heavy metal content in hair varied across sexes and ages. Pb concentration in hair would decrease as age increased. The highest Pb concentration appeared in children between ages 0 and 10, the amount of which was significantly different from that in other age groups; hence, children appear to be more susceptible to Pb pollution than other ages. Contents of Cr, Fe, Zn, and As in hair would also increase with age; Fe content in hair was particularly correlated with age. The contents of Cr, Pb, Fe, and As in men's hair were higher than those in women's, whereas the case of Cu and Zn was just the opposite. There were significant differences between sexes concerning the contents of Cr, Cu, and As, and a highly significant difference about Zn between sexes as well. These results indicated that the contents of heavy metal in residents' hair would be closely related to the features of the local environment and population.

Radon emanation from human hair

Bio-indicator of long time exposure to pollutants, human hair is studied in contaminated areas. The number of studies on background environments remains small, and factors impacting human hair radioactivity in contaminated and background areas remain poorly known. Radon-222, a radioactive noble gas of half-life 3.8 days, is the alpha decay daughter of radium-226 in the uranium-238 chain. Radon emission depends on radium concentration (C_Ra) and probability of decaying radium to liberate radon (i.e., the emanation coefficient E). The radon-222 emanating power (i.e., radon emanation or effective radium-226 concentration, EC_Ra) is measured in the laboratory from human hair of a cohort of 93 individuals living in uranium non-contaminated areas using a high-sensitivity method based on 371 long accumulation sessions. E of human hair is also determined. EC_Ra values from human hair are heterogeneous, ranging from 0.059 ± 0.008 to 3.7 ± 0.1 Bq kg^-1 (mean: 0.484 ± 0.006 Bq kg^-1). We find 2.6 ± 0.1 and 2.5 ± 0.1 times larger values for females than males and for color-treated than natural hair, respectively. By contrast, E is homogeneous (mean: 0.33 ± 0.11; n = 9). Our data suggest a different behavior of accumulation/elimination processes of heavy elements in females and non-negligible radium concentration in hair dye products. Our results demonstrate ²²⁶Ra-²³⁸U disequilibrium in human hair, indicating secondary radium intake, and that EC_Ra mainly depends on C_Ra. Other factors such as age and sampling time are also studied. The impact of factors on EC_Ra from human hair in uranium non-contaminated areas is ordered as follows: (body site?) > sex > hair dyeing > dietary/drinking habits > natural color > time period > geographical location > age. Any human hair-based study should take into consideration these factors. Our method, cost-effective and easy to implement, may be applied to large numbers of samples for large-scale epidemiological studies, and may also be useful for criminal investigations.

The Association between Mineral and Trace Element Concentrations in Hair and the 10-Year Risk of Atherosclerotic Cardiovascular Disease in Healthy Community-Dwelling Elderly Individuals

This cross-sectional analysis included 137 Korean subjects aged 60⁻79 years. All subjects underwent anthropometric measurements and laboratory tests. Scalp hair samples were obtained from each individual, the concentrations of 36 minerals and trace elements were analyzed, and 16 ratios of elements were calculated. ASCVD risk was estimated using pooled cohort ASCVD risk assessment equations for 10-year risk profiles. The 137 subjects were divided into three risk groups: low (<5%, n = 28), intermediate (5% to <7.5%, n = 21), and high (≥7.5%, n = 88) risk groups. After adjusting for obesity (BMI ≥ 25 kg/m²) and sex, Na concentration (mg%) in hair was significantly lower in the low-risk (13.91 ± 7.02) than in the intermediate-risk (47.18 ± 8.08) and high-risk (36.76 ± 3.95) groups (p for trend = 0.024). The concentration of K (mg%) in hair was also positively associated with the severity of ASCVD risk (10.50 ± 8.37, 23.62 ± 9.63, 33.31 ± 4.71, respectively; p for trend = 0.017), but their differences were not statistically significant (p = 0.059). By contrast, the levels of Co, U, and Hg, and the Ca/P and Ca/Mg ratios, were negatively correlated with the severity of ASCVD risk (p for trend < 0.05). Mean Na concentration in hair was significantly lower in the low-risk than in the other risk groups. By contrast, Co, U, and Hg concentrations showed significant negative associations with risk severity. Further studies are needed to assess whether dietary modification for trace elements could lower the risk of ASCVD.

Strontium isotope ratios of human hair from the United States: Patterns and aberrations

RATIONALE

Strontium isotope ratios (⁸⁷ Sr/⁸⁶ Sr) of hair may be a valuable tool to estimate human provenance. However, the systematics and mechanisms controlling spatial variation in ⁸⁷ Sr/⁸⁶ Sr of modern human hair remain unclear. Here, we measure ⁸⁷ Sr/⁸⁶ Sr of hair specimens from across the USA to assess the presence of geospatial relationships.

METHODS

Ninety-eight human hair specimens were collected from salon/barbershop floors in 48 municipalities throughout the conterminous USA. [Sr] and ⁸⁷ Sr/⁸⁶ Sr ratios were measured from hair using quadrupole and multi-collector inductively coupled plasma mass spectrometers, respectively. The [Sr] and ⁸⁷ Sr/⁸⁶ Sr ratios of hair were compared with the measured [Sr] and ⁸⁷ Sr/⁸⁶ Sr ratios of tap waters from the collection locations. In addition, the ⁸⁷ Sr/⁸⁶ Sr ratio of hair was compared with the modeled ratios of bedrock and surface waters.

RESULTS

Hair color was independent of the ⁸⁷ Sr/⁸⁶ Sr ratio, but related to [Sr]. The ⁸⁷ Sr/⁸⁶ Sr ratios of hair and leachate were not statistically different and were positively correlated; however, in several hair-leachate pairs, the ratios were conspicuously different. The ⁸⁷ Sr/⁸⁶ Sr ratios of both hair and leachate were linearly correlated with tap water. The ⁸⁷ Sr/⁸⁶ Sr ratio of hair was also significantly correlated with the modeled ratio of bedrock and surface waters, although the ⁸⁷ Sr/⁸⁶ Sr ratio of hair was most strongly correlated with the measured ratio of tap water.

CONCLUSIONS

The ⁸⁷ Sr/⁸⁶ Sr ratio of hair is related to the ratio of tap water, which varied geographically. The ratio of hair provided geographic information about an individual's recent residence. Differences in the ⁸⁷ Sr/⁸⁶ Sr ratios of hair and hair leachate may be concomitant with travel and could potentially be used as a screening tool to identify recent movements.

Strontium isotope ratios (87 Sr/86 Sr) of human fingernail clippings reveal multiple location signals

RATIONALE

Strontium isotope ratios (⁸⁷ Sr/⁸⁶ Sr) in human fingernail keratin tissues have been underexplored for region of origin and travel history reconstruction studies. Here we investigated ⁸⁷ Sr/⁸⁶ Sr ratios in fingernail keratin to establish baseline measurements in a resident group and to examine how ⁸⁷ Sr/⁸⁶ Sr ratios changed with relocation.

METHODS

Fingernail clippings were collected from resident (n = 10) and non-resident/traveler groups (n = 4 and n = 4) that were part of a larger study in Salt Lake City (UT, USA) from 2015 to 2016. Strontium abundance and ⁸⁷ Sr/⁸⁶ Sr ratios were determined via multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). ⁸⁷ Sr/⁸⁶ Sr and oxygen (δ¹⁸ O) isotope ratios from the traveler participants were compared to examine temporal patterns.

RESULTS

Strontium abundance and ⁸⁷ Sr/⁸⁶ Sr ratios in fingernails from the resident group established a baseline against which we could evaluate potential differences in non-resident/traveler groups. Resident ⁸⁷ Sr/⁸⁶ Sr ratios remained constant over the study period and were consistent with previously measured tap waters for the area. ⁸⁷ Sr/⁸⁶ Sr ratio changes in non-resident/traveler groups were rapid and reflected the current location of the individual within 4-5 weeks of arrival. Lastly, δ¹⁸ O and ⁸⁷ Sr/⁸⁶ Sr ratios of the same fingernail clippings did not exhibit similar temporal patterns, since fingernail δ¹⁸ O ratios required more time to attain values characteristic of the new environment.

CONCLUSIONS

Our findings suggest that strontium is incorporated into fingernail tissues differently from hair and this could be advantageous to forensic investigations. We found that ⁸⁷ Sr/⁸⁶ Sr and δ¹⁸ O ratios of the same fingernail clippings revealed two different time points reflecting an individual's residence over short- (4-5 weeks, ⁸⁷ Sr/⁸⁶ Sr ratios) and long-term (3-5 months, δ¹⁸ O values) time scales. It is likely that the ⁸⁷ Sr/⁸⁶ Sr ratios of fingernail clippings reflect exogenous signals that are incorporated through bathing waters and that these signals change rapidly with movement to a new location. Our results may aid future forensic studies in the determination of region of origin in unidentified remains.

Evaluation of the status and the relationship between essential and toxic elements in the hair of occupationally exposed workers

Lead poisoning is a common disease in lead-acid battery manufacturing industries. Workers can be also exposed to various toxic elements present as contaminants or used as catalysts to enhance batteries' performances. In the present study, levels of essential and toxic elements and their relationship were assessed by analyzing scalp hair samples of 52 workers in a Pb battery manufacturing plant. The impact of some confounding factors on hair mineral contents was also investigated. For comparative purposes, nonoccupationally exposed subjects were selected as controls. All elements were determined by triple quadrupole ICP-MS. The results indicated significantly higher levels of Pb, Sb, As, and Cd in the hair of workers when compared to controls (p < 0.01). The Spearman correlation test revealed significant correlations between Pb/Cr, Pb/Mn, Pb/Ni, Pb/As, Pb/Se, Pb/Sb, Hg/As, Hg/Sn, Hg/Sb, Sb/Cr, Sb/As, Sb/Se, Sb/Cd, Sb/Sn, Sn/Cr, Sn/As, Sn/Cd, Cd/As, Se/Ni, As/Cr, Ni/Cr, Ni/Mn, and Mn/Cr in the hair of workers and Pb/Cr, Pb/Mn, Pb/Ni, Pb/Cd, Mn/Ni, Mn/Cd, Cd/Ni, As/Ni, Sn/Ni, Sb/Sn, and Hg/Sn in the hair of controls. Multiple linear regression analysis revealed linear dependence including Cr = f(Pb, Ni, Sb), Mn = f(Ni, Sb), Ni = f(Mn, Cr, -Cd) (Cd was negatively correlated, β < 0), As = f(Sn, Sb, Hg), Se = f(Ni); Sn = f(As), Sb = f(As, Mn, -Hg, Sn, Se, -Ni) (Hg and Ni were negatively correlated), Hg = f(As, -Sb, Sn) (Sb was negatively correlated), and Pb = f(Cr). The result of this study can be very useful to explain the interactions between elements or for comparison studies when establishing reference ranges or monitoring elements in workplaces.

Comparative Hair Trace Element Profile in the Population of Sakhalin and Taiwan Pacific Islands

The objective of the current study is to perform a comparative analysis of hair trace element content in 393 apparently healthy adults living in Taipei, Taiwan, Republic of China (94 women and 46 men) and Yuzhno-Sakhalinsk, Sakhalin, Russia (186 women and 67 men). The obtained data indicate that Yuzhno-Sakhalinsk inhabitants were characterized by significantly higher hair Co, Cr, Mn, and V levels, exceeding the respective Taipei values by a factor of 3, 2, 7, and 5, respectively (all p < 0.001). Hair Cu, Fe, and Si levels were also higher in examinees from Yuzhno-Sakhalinsk than those from Taipei by 10% (p = 0.001), 61% (p < 0.001), and 68% (p < 0.001), respectively. It is notable that the only essential element, being significantly higher (+ 30%; p < 0.001) in Taipei inhabitants, is selenium. Yuzhno-Sakhalinsk inhabitants were characterized by 60% higher levels of hair Sn, and nearly two- and threefold higher scalp hair content of Be and Cd in comparison to Taipei values, respectively (all p < 0.001). Oppositely, the examinees from Taipei had 14% (p = 0.040) and 47% (p = 0.001) higher levels of hair As and Hg as compared to Yuzhno-Sakhalinsk inhabitants. Further analysis demonstrated that men from both Yuzhno-Sakhalinsk and Taipei were characterized by significantly higher hair Mn, As, and Pb levels in comparison to women. The intensive development of heavy industry in Yuzhno-Sakhalinsk may result in increased metal emissions, whereas fish consumption may result in elevation of hair Hg, As, and Se levels in Taiwan inhabitants.

The health hazards of potentially toxic metals in the daily diets of adults and children from a mining and smelting region (Hezhang County) in southwestern China

Toxic metals accumulated in the human body are predominantly absorbed by the digestive tract in non-occupationally exposed populations. In the current study, we collected plowed soil samples, and investigated the varied food compositions in a mining and smelting area in southwestern China, to measure the concentrations of ten potentially toxic metals-As, Ba, Cd, Cr, Cu, Mn, Ni, Pb, Sr, and Zn. We collected information on the daily intakes of these metals to assess the health risks associated with their exposure among children and adults. The urine concentrations of the metals were also measured to obtain data on the amounts present in the body. The results showed that the hazard indexes (HIs) of As, Ba, Cd, Cr, Ni, Pb, and Sr were all larger than 1, for both adults and children; the Zn and Cu values were comparatively higher in children. The intake of staple foods of the region posed the greatest health risk, while drinking water only posed risks clearly associated with As exposure. The urine samples of local residents contained larger amounts of As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn, confirming the hazards in the health risk assessment. Obvious differences in the urine metal concentrations between men and women were confirmed. In conclusion, higher concentrations of metals in the surface soil and rain water were the predominant cause of elevated exposure through home-grown crops and produce to accumulate in local residents' bodies.

Strontium isotope ratios of human hair record intra-city variations in tap water source

The oxygen (¹⁸O/¹⁶O) isotope analysis of hair is commonly applied to reconstruct an individual’s residence history. However, region-of-origin as determined from oxygen isotope values (δ¹⁸O) alone is often spatially indistinct. Adding additional geochemical recorders can refine region-of-origin estimates. In this capacity, strontium (⁸⁷Sr/⁸⁶Sr) isotope analysis has attracted increased interest. While ⁸⁷Sr/⁸⁶Sr reflects the influences of local geology, ⁸⁷Sr/⁸⁶Sr of hair includes both external environmental signals as well as the internal dietary indicators. To better understand the impact of these contributions to the spatial signal encoded within ⁸⁷Sr/⁸⁶Sr of hair, human hair was collected from three locations within Salt Lake City, Utah along with the donor’s sex. The ⁸⁷Sr/⁸⁶Sr and δ¹⁸O of hair and local tap water were measured. There were no significant relationships between sex and either δ¹⁸O or ⁸⁷Sr/⁸⁶Sr of hair, nor between collection location and the δ¹⁸O of hair. However, we found significant associations between collection location and ⁸⁷Sr/⁸⁶Sr of hair. These findings suggest that interactions with local water may be an important source of Sr to human hair and that the ⁸⁷Sr/⁸⁶Sr of hair may have the capacity to record differences in ⁸⁷Sr/⁸⁶Sr of tap waters on small spatial scales.

Distribution of metal and metalloid elements in human scalp hair in Taiyuan, China

This study investigated the levels of metal and metalloid elements (As, Ca, Cd, Cr, Cu, Fe, Hg, Mg, Ni, Pb, and Zn) in scalp hair samples collected from 161 people of different age and gender groups living in the six districts of Taiyuan, an industrial city with rich coal reserve in Shanxi province in China. Levels of most elements in the hair were high in the 26-40 age groups and increased with the length of residence. Calcium, Cr, Mg, Ni and Zn levels in the females' hair were significantly higher than those in the males' (p < 0.05). Element levels in the hair didn't have significantly differences between industrial and non-industrial districts because most of industry factories are in the upper wind position in Taiyuan, and contamination is prone to spread to non-industrial districts. The principal component analysis indicates that the main sources of these elements are mining activities, the neighboring stainless steel industry, and coal combustion. These results indicate that the industrial activities primarily contribute to the metal and metalloid pollution in Taiyuan, whereas numerous factors caused the metals accumulation in hair.

Effects of sex on the levels of metals and metalloids in the hair of a group of healthy Spanish adolescents (13 to 16 years old)

Human biomonitoring can be a reliable tool to protect the health of the citizens of major urban environments. Human hair may be an invaluable specimen to determine chronic exposure to any environmental contaminant in an individual, especially in the young population. However, different factors including a lack of studies that have established reference values for metals and metalloids (trace elements) in human scalp hair make the use of this matrix controversial. A monitoring study was performed to establish possible normal or tentative reference values of Al, As, Be, Cd, Cr, Cu, Hg, Mn, Pb, Sn, Ti, Tl and Zn in adolescents' (aged 13-16) hair who have lived since birth in Alcalá de Henares, Madrid region (Spain). Strict inclusion criteria were followed to study the effect of sex on the hair metal content, and the levels of the above contaminants were also studied in park topsoils from Alcalá de Henares. Scalp hair samples were collected from 96 healthy adolescents (28 boys and 68 girls), and reference values were calculated following the recommendations of the International Union of Pure and Applied Chemistry. The levels of Cd, Cu, Pb, Sn and Zn in hair of adolescents from Alcalá de Henares show a sex dependency, being significantly higher in female participants. Sex should be a factor taken into account when developing future reference values and hair metal content. Soil metal contamination was not correlated with the levels found in hair. To conclude, the values of metals and metalloids here analysed and discussed could be considered as tentative reference values for Spanish adolescents aged 13-16 years living in the Madrid region, and may be used to identify the level of exposure of adolescents in this Spanish region to the various metals and metalloids.