Heavy Metals in Fingernails and Scalp Hair of Children, Adults and Workers from Environmentally Exposed Areas at Aswan, Egypt

Characteristics of heavy metals in the hair of firefighters: concentration dynamics and elemental interactions

Heavy metal pollution poses a major threat to human health. Firefighters, a high-risk occupational group, are regularly exposed to airborne heavy metals and fly ash. Consequently, detailed investigations into their heavy metal exposure levels are essential. This study evaluated the heavy metal exposure of 14 firefighters across five stages before and after firefighting, with a focus on concentration trends and element interactions. The concentration order was Zn > Cu > Fe > Pb > Mn > Cr > As > Ni > Cd > Co. Comparisons with health reference values and other regions indicated that while most metals were within reference ranges, Zn concentrations were elevated. The elevated Zn concentrations may result from its attachment to hair through chemisorption and absorption from airborne particles and fly ash during combustion. Heavy metal concentrations in the hair of firefighters increased after firefighting, and continued firefighting missions may further accumulate heavy metals in the body. However, concentrations decreased after a period of firefighting. Correlation analysis revealed that, except for Zn, metals exhibited synergistic interactions, with correlations strengthening significantly after firefighting. Variation in heavy metals reflects long-term pollutant exposure, and Zn in hair may serve as a biomarker of fire-related exposure.

Internal Cumulated Dose of Toxic Metal(loid)s in a Population Residing near Naturally Occurring Radioactive Material Waste Stacks and an Industrial Heavily Polluted Area with High Mortality Rates in Spain

Huelva is a city in SW Spain with 150,000 inhabitants, located in the proximity of two heavy chemical industry complexes, the highest naturally occurring radioactive material (NORM) waste (phosphogypsum) stacks of Europe and a highly polluted estuary, with elevated cardiovascular disease and cancer mortality rates. This study analyses the association between cumulated exposure levels to 16 metal(loid)s (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se, Tl, U, V, and Zn) measured in the toenail of a sample (n = 55 participants) of the general control population of Huelva City who were involved in the MCC-Spain study and the spatial proximity patterns to the local polluting sources. Residents of the city of Huelva have higher levels of Fe, Ni, Cr, Se, As, and Co in their toenails compared to the levels found in populations with similar characteristics living in non-polluted areas. Moreover, the highest concentrations of As, Pb, Cd, Mo, and Se were found in toenails of participants living near the NORM waste stack, while the highest Cu, Zn, and Al contents corresponded to people residing near the industrial area. The spatial distribution of most of the metal(loid)s studied appears to be mainly controlled by anthropogenic factors.

Human biomonitoring of trace metals from different altitudinal settings of Pakistan

Human biomonitoring of toxic trace elements is of critical importance for public health protection. The current study aims to assess the levels of selected trace metals (Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) into paired human nail and hair samples (n = 180 each) from different altitudinal setting along the Indus River, and which were measured by using inductively coupled plasma mass spectrometry (ICP-MS). The human samples (hair and nail) were collected from four different ecological zones of Pakistan which include frozen mountain zone (FMZ), wet mountain zone (WMZ), riverine delta zone (RDZ), and low-lying southern areas (LLZ). Our results showed the following occurrence trends into studied hair samples: higher values (ppm) of Zn (281), Co (0.136), and Mn (5.65) at FMZ; Cr (1.37), Mn (7.83), and Ni (1.22) at WMZ; Co (0.15), Mn (11.89), and Ni (0.99) at RDZ; and Mn (8.99) and Ni (0.90) at LLZ. While in the case of nails, the levels (ppm) of Mn (9.91) at FMZ and Mn (9.38, 24.1, and 12.5), Cr (1.84, 3.87, and 2.33), and Ni (10.69, 8.89, and 12.6) at WMZ, RDZ and LLZ, respectively, showed higher concentration. In general, among the studied trace elements, Mn and Ni in hair/nail samples were consistently higher and exceeded the WHO threshold/published reference values in most of the studied samples (> 50-60%) throughout the Indus basin. Similarly, hair/nail Pb values were also higher in few cases (2-10%) at all studied zones and exceeded the WHO threshold/published reference values. Our area-wise comparisons of studied metals exhibited altitudinal trends for Cd, Cr, Zn, and Mn (p < 0.05), and surprisingly, the values were increasing from south to north (at higher altitudes) and indicative of geogenic sources of the studied toxic elements, except Mn, which was higher at lower floodplain areas. Estimated daily intake (EDI) values showed that food and drinking water had the highest contribution towards Zn, Cu, Mn, and Ni and accumulation at all studied zones. Whereas, dust also acts as the main exposure route for Mn, Co, Cr, and Cd followed by the food, and water.

Assessment and Exposure Analysis of Trace Metals in Different Age Groups of the Male Population in Southern Punjab, Pakistan

In developing countries, like Pakistan, the pursuit of urbanization and economic development disrupts the delicate ecosystem, resulting in additional biogeochemical emissions of heavy metals into the human habitat and posing significant health risks. The levels of these trace elements in humans remain unknown in areas at higher risk of pollution in Pakistan. In this investigation, selected trace metals including Copper (Cu), Chromium (Cr), Lead (Pb) Cadmium (Cd), Cobalt (Co), Nickel (Ni), and Arsenic (As) were examined in human hair, urine, and nail samples of different age groups from three major cities (Muzaffargarh, Multan, and Vehari) in Punjab province, Pakistan. The results revealed that the mean concentrations (ppm) of Cr (1.1) and Cu (9.1) in hair was highest in Muzaffargarh. In urine samples, the mean concentrations (μg/L) of Co (93), As (79), Cu (69), Cr (56), Ni (49), Cd (45), and Pb (35) were highest in the Multan region, while As (34) and Cr (26) were highest in Vehari. The mean concentrations (ppm) of Ni (9.2), Cr (5.6), and Pb (2.8), in nail samples were highest in Vehari; however, Multan had the highest Cu (28) concentration (ppm). In urine samples, the concentrations of all the studied metals were within permissible limits except for As (34 µg/L) and Cr (26 µg/L) in Vehari. However, in nail samples, the concentrations of Ni in Multan (8.1 ppm), Muzaffargarh (9 ppm), Vehari (9.2 ppm), and Cd (3.69 ppm) in Muzaffargarh exceeded permissible limits. Overall, the concentrations of metals in urine, nail, and hair samples were higher in adults (39-45 age group). Cr, Cu, and Ni revealed significantly higher concentrations of metals in hair and water in Multan, whereas As in water was significantly (p < 0.001) correlated with urinary As in Multan, indicating that the exposure source was region-specific.

Quantitative analysis of human hairs and nails

Hair and nails are human biomarkers capable of providing a continuous assessment of the concentrations of elements inside the human body to indicate the nutritional status, metabolic changes, and the pathogenesis of various human diseases. Laser-induced breakdown spectroscopy (LIBS) and X-ray fluorescence (XRF) spectrometry are robust and multi-element analytical techniques able to analyze biological samples of various kinds for disease diagnosis. The primary objective of this review article is to focus on the major developments and advances in LIBS and XRF for the elemental analysis of hair and nails over the last 10-year period. The developments in the qualitative and quantitative analyses of human hair and nail samples are discussed in detail, with special emphasis on the key aspects of elemental imaging and distribution of essential and non-essential elements within the hair and nail tissue samples. Microchemical imaging applications by LIBS and XRF (including micro-XRF and scanning electron microscopy, SEM) are also presented for healthy as well as diseased tissue hair and nail samples in the context of disease diagnosis. In addition, main challenges, prospects, and complementarities of LIBS and XRF toward analyzing human hair and nails for disease diagnosis are also thoroughly discussed here.

Trace Element Levels in Nails of Residents of Addis Ababa Are Shaped by Social Factors and Geography

The Akaki catchment in Ethiopia is home to Addis Ababa and about five million people. Its watercourses receive a variety of wastes released by the residents and industries. River water is being used for irrigation, livestock watering, and other domestic purposes. This study tested the hypothesis that the river pollution would be reflected in higher levels of trace elements in the nails of residents living in Akaki-Kality Sub-City in the downstream, as compared to those living in Gullele Sub-City in the upstream of the Akaki catchment. Samples were taken and subsequently analysed for metals using inductively coupled plasma optical emission spectrometry (ICP-OES). The mean concentrations of Fe, Zn, Cu, Mn, Ni, Cr, Pb, and As in nails from Akaki-Kality were 488 ± 49, 106 ± 10, 5.2 ± 0.3, 13 ± 1.5, 11 ± 8, 2.2 ± 0.3, 0.09 ± 0.01, and 0.16 ± 0.01 μg/g, respectively. Likewise, the concentrations of Fe, Zn, Cu, Mn, Ni, Cr, Pb, and As in nails from Gullele were 1035 ± 135, 251 ± 10, 6.6 ± 0.4, 31 ± 3.7, 7.4 ± 1.7, 2.0 ± 0.3, 0.63 ± 0.01, and 0.25 ± 0.01 μg/g, respectively. Co and Cd were not detected. Contrary to the initial hypothesis, higher metal levels were found in nails of residents living in the upstream rather than the downstream area of the catchment. In particular, the concentrations of Fe (p = 0.000), Zn (p = 0.01), and Mn (p = 0.000) were significantly elevated in nails from Gullele and also high in comparison with internationally reported values. Besides, geography and social factors, especially education level, correlated to trace metals in nails. Most of the elements were significantly lower in the nails of individuals with a university degree compared to those who were illiterate or only completed primary school.

Concentration of selected elements in the hair of Madagascar girls in relation to nutritional status and place of residence

Although the children malnutrition in Madagascar and the environmental pollution of this country has been widely discussed, there is no research on the differences in toxic elements accumulation in human body in dependence on nutritional status of Malagasy. Nine elements concentration (Al, As, Cd, Cr, Hg, Ni, Pb, Sn and Sb) was determined in scalp hair of 103 schoolgirls (8–15 years old), living in two areas: urban – close to Antananarivo (UR) and rural Berevo region (RU). Samples were analysed by an inductively coupled plasma optical emission spectrometer. The nutritional status was evaluated by Cole’s index. Underweight was related to higher accumulation of Al, Cd and Cr in the hair girls, and more common among girls living in RU than UR region (42 % v. 28 %). Two-factor ANOVA showed differences in the Al and Cr content in the girls’ hair depending both on their place of residence and nutritional status. This indicates additional consequence of malnutrition to the girls development and health.

Characterization of the Toxicological Impact of Heavy Metals on Human Health in Conjunction with Modern Analytical Methods

Increased environmental pollution, urbanization, and a wide variety of anthropogenic activities have led to the release of toxic pollutants into the environment, including heavy metals (HMs). It has been found that increasing concentrations of HMs lead to toxicity, mineral imbalances, and serious diseases, which are occurring more and more frequently. Therefore, testing has become imperative to detect these deficiencies in a timely manner. The detection of traces of HMs, especially toxic ones, in human tissues, various biological fluids, or hair is a complex, high-precision analysis that enables early diagnosis, addressing people under constant stress or exposed to a toxic environment; the test also targets people who have died in suspicious circumstances. Tissue mineral analysis (TMA) determines the concentration of toxic minerals/metals at the intracellular level and can therefore determine correlations between measured concentrations and imbalances in the body. Framing the already-published information on the topic, this review aimed to explore the toxicity of HMs to human health, the harmful effects of their accumulation, the advantages vs. the disadvantages of choosing different biological fluids/tissues/organs necessary for the quantitative measurement of HM in the human body, as well as the choice of the optimal method, correlated with the purpose of the analysis.

Rare Earth Elements Accumulation in the Hair of Malagasy Children and Adolescents in Relation to Their Age and Nutritional Status

Due to undesired influence, the accumulation of rare earth elements (REE) in the human body has been discussed recently. However, it is usually limited to the study of the population living where REE ores and mines are located. The aim of the experiment presented was to analyse the concentration of REE in the hair of children and teenagers living in two areas of Madagascar in relation to the place of residence, nutritional status, age and sex. REE concentration was determined in scalp hair of 262 of subjects (5–19 years old) by an inductively coupled plasma-optical emission spectrometer. The content of total REE in the Malagasy hair was in the range of 0.79–44.15 mg/kg. The nutritional status was evaluated by Cole’s index, and malnutrition of children was observed more often in village areas. The concentration of these elements was also determined in 20 samples for the estimation of environmental exposure. No significant differences were detected in the content of these elements in the studied regions, although the mean value was always higher in soil samples from the Antananariva region. The obtained data suggest dependence between REE concentration in the hair and age, and nutritional status of the examined subjects. Even if the observed correlations are weak, they contribute significant knowledge on the accumulation of REE in the bodies of children living in areas that are not recognised as deposits of these elements.

Childhood exposure to metal(loid)s in industrial and urban areas along the Persian Gulf using toenail tissue as a biomarker

Metal(loid)s (MLs) with natural or anthropogenic sources may cause adverse health effects in children. This study aimed to compare the childhood exposure to ΣMLs (essential, non-essential and toxic) in an industrial and an urban area in Southwest Iran using toenail tissue as a biomarker. The present study was carried out with school children in the age range of 7-12 years, who were living in an industrial area in the petrochemical and gas area (PGA) of the Central District of Asaluyeh County and in an urban area (UA) located in the Kaki District. A total of 270 boys and girls were recruited in January to April 2019. The ICP-MS was used for determination of the studied MLs. A multi-linear regression model was constructed to assess the effect of residence area on toenail ML levels. A significantly higher level of ΣMLs in toenail from the PGA was observed compared to the level in the UA (8.839 vs. 7.081 μg/g, β = -0.169 and p < 0.05). However, all of the 15 MLs studied were detected in the toenail samples from both study sites. Significant differences for the mean Cr (β = -0.563), Fe (β = -0.968), Mn (β = -0.501), Ni (β = -0.306), and Pb (β = -0.377) levels were found between toenail samples from the study areas (p < 0.05), with higher levels in the PGA. The results of this study suggest that children in industrial area are prone to a greater risk for ML exposures compared with those living in a non-industrial urban area.

Exposure of the residents around the Three Gorges Reservoir, China to chromium, lead and arsenic and their health risk via food consumption

Hydrological management of the Three Gorges Dam has resulted in the interception of heavy metals in the Three Gorges Reservoir (TGR). However, the exposure to heavy metals and health risks among local residents remained poorly understood. Here we collected 208 biomarker samples (hair) and 20 food species from typical regions in the TGR to assess the exposure levels of three toxic metals (Cr, Pb and As) in residents of the TGR, and subsequently investigated their health risk via dietary intake. Results indicated that hair Cr and As levels were below the reference value for normal people and threshold of skin lesions, respectively, whereas about 22% hair Pb exceeded the reference for clinical medicine, indicating a potential Pb exposure of local residents. Smoking habit and fish consumption were found to be predictors for hair Pb. In addition, the concentrations of heavy metals in all investigated food samples were below the limits of contaminants in food in China, except for Pb in the sweet potato and fish. The estimated daily intake of metals (DIMs) revealed that the intakes of Cr and As from studied food were under the recommended thresholds of Cr and As. However, the intake of Pb via diet exceeded the limit of the prevalence of chronic kidney disease and closed to the threshold for cardiovascular, which was probably associated with the high Pb concentrations of fish and sweet potato. Overall, residents around the TGR were at low exposure to Cr and As, but Pb exposure may need more attention.

Impact of smoking on heavy metal contamination and DNA fragmentation

Tobacco is smoked by different techniques through cigarette and shisha smoking. The prevalence of tobacco is considered one of the major threats to public health. This study aims to assess the effect of cigarette, shisha, and mixed (cigarette/shisha) smoking on heavy metal contamination in hair samples, hair loss, and DNA fragmentation, to correlate age, incidence of hair loss, and smoking duration with the amount of accumulated metals and the DNA fragmentation, and to correlate the level of heavy metal contamination with DNA fragmentation. This study was implemented in Saudi Arabia among sixty males divided into four groups (15/group): control and cigarette, shisha, and mixed smokers. Heavy metal contamination in hair samples and urinary DNA levels were assayed. All metal and urinary DNA levels were significantly elevated in cigarette, shisha, and mixed smokers compared to non-smokers. Hair loss was also higher among smokers especially among participants with high DNA concentrations. There were positive significant correlations of age and incidence of hair loss with urinary DNA concentration. There were positive significant correlations between urinary DNA concentration and all heavy metal levels. Cigarette, shisha, and mixed smoking trigger metal contamination, DNA fragmentation, and hair loss. Moreover, hair loss was observed to be associated with Sb, Cd, and Ni as well as urinary DNA level, while age was associated only with lead and urinary DNA levels. The duration of smoking had a major impact on Pb and Sb levels. Finally, contamination with all six metals was significantly associated with DNA fragmentation.

Using human hair and nails as biomarkers to assess exposure of potentially harmful elements to populations living near mine waste dumps

Potentially harmful elements (PHEs) manganese (Mn), cobalt (Co), copper (Cu), lead (Pb), nickel (Ni) and zinc (Zn) were measured in human hair/nails, staple crops and drinking water to ascertain the level of exposure to dust transference via wind and rain erosion for members of the Mugala community living near a mine waste dump in the Zambian Copperbelt. The mean PHE concentrations of hair in decreasing order were Zn (137 ± 21 mg/kg), Cu (38 ± 7 mg/kg), Mn (16 ± 2 mg/kg), Pb (4.3 ± 1.9 mg/kg), Ni (1.3 ± 0.2 mg/kg) and Cr (1.2 ± 0.2 mg/kg), Co (0.9 ± 0.2 mg/kg) and Cd (0.30 ± 0.02 mg/kg). Whilst for toenails the decreasing order of mean concentrations was Zn (172 ± 27 mg/kg), Cu (30 ± 5 mg/kg), Mn (12 ± 2 mg/kg), Pb (4.8 ± 0.5 mg/kg), Ni (1.7 ± 0.14 mg/kg) and Co (1.0 ± 0.02 mg/kg), Cr (0.6 ± 0.1 mg/kg) and Cd (0.1 ± 0.002 mg/kg). The concentration of these potentially harmful elements (PHEs) varied greatly among different age groups. The results showed that Mn, Co, Pb, Cd and Zn were above the interval values (Biolab in Nutritional and environmental medicine, Hair Mineral Analysis, London, 2012) at 0.2-2.0 mg/kg for Mn, 0.01-0.20 mg/kg for Co, < 2.00 mg/kg for Pb, < 0.10 mg/kg for Cd and 0.2-2.00 mg/kg for Zn, whilst Ni, Cu and Cr concentrations were within the normal range concentrations of < 1.40 mg/kg, 10-100 mg/kg and 0.1-1.5 mg/kg, respectively. Dietary intake of PHEs was assessed from the ingestion of vegetables grown in Mugala village, with estimated PHE intakes expressed on a daily basis calculated for Mn (255), Pb (48), Ni (149) and Cd (33) µg/kg bw/day. For these metals, DI via vegetables was above the proposed limits of the provisional tolerable daily intakes (PTDIs) (WHO in Evaluation of certain food additive and contaminants, Seventy-third report of the Joint FAO/WHO Expert Committee on Food Additives, 2011) for Mn at 70 µg/kg bw/day, Pb at 3 µg/kg bw/day, Ni and Cd 5 µg/kg bw/day and 1 µg/kg bw/day, respectively. The rest of the PHEs listed were within the PTDIs limits. Therefore, Mugala inhabitants are at imminent health risk due to lead, nickel and cadmium ingestion of vegetables and drinking water at this location.

Heavy metal toxicity from the leather industry in Bangladesh: a case study of human exposure in Dhaka industrial area

Activities in the Bangladeshi leather industries have the potential to cause chemical pollutions thereby deteriorating the working environments, the surrounding residential areas, or even foodstuffs. Therefore, it is important to determine the chemical exposures among the industry workers and residents of the surrounding areas who may be directly or indirectly impacted by the contaminated environment. This study focused on evaluating the hazard arising from exposure to metals due to industrial contamination. Tissue samples of hair and nails were collected from both the leather industry workers and residents in the vicinity of the industries. Using chromium as an indicator of contamination/exposure from the leather industry, it was the most significant metal contaminant for industry workers ranging from 21.85 to 483 mg/kg and for industry-neighboring residents at 6.01 to 296.16 mg/kg. Both the workers and neighboring residents were found to be excessively exposed (P < 0.05) to chromium compared with the investigated control group of people living in a distant village area which had no industrial establishments.

Heavy metals as criteria of health and ecological well-being of the urban environment

The study of the content of Pb, Cd, Ni, Zn, Mn, Cr, and Cu in biological media (the hair) of children living in the zones of the city of Kazan with different pollution levels was carried out. The identification of the zones in the city of Kazan was performed on the basis of the snow cover and soils pollution with heavy metals, which are natural accumulators of chemical substances and heavy metals (HM). Statistically significant differences (р < 0.01) in the content of certain metals in the hair, lead and cadmium in particular, were revealed in children living in the technologically polluted zone (Teplocontrol). Microelement composition of the hair in children with respiratory diseases (RD) varied widely in the content of lead (р < 0.05), and a statistically significantly lower level of zinc (р < 0.01) and copper (р < 0.05) compared with all the rest groups of children was determined in genitourinary diseases (GUD). However, relatively high values of toxic elements in the control zone show that the ecological status of the city and region is instable, and implies additional measures of the environmental monitoring and activities on chemical safety in certain city zones.

Interaction of Lead with Calcium, Iron, and Zinc in the Biological Samples of Malnourished Children

Interaction between toxic and essential elements is of particular interest, because the deficiency of essential element can dramatically increase the absorption rate of toxic metals inside the body. This study was conducted to evaluate the possible correlation of lead (Pb) with calcium (Ca), iron (Fe), and zinc (Zn) in biological samples (whole blood and scalp hair) of malnourished children (MNC). For comparative purposes, age-matched, well-nourished children (WNC) were selected. The concentrations of understudy elements were analyzed by atomic absorption spectrophotometry after microwave acid digestion. The accuracy of the methodology, as well as its its validity and efficiency, was checked through certified reference material of whole blood and scalp hair. The result indicates that the MNC have a twofold higher level of Pb, while the levels of essential elements (Ca, Fe, and Zn) were onefold to twofold lower as compared to the WNC (p < 0.05). Significant negative correlations of Pb with Ca, Fe, and Zn were found in the studied malnourished population at p < 0.05. Further research studies are required to elucidate the role of these metals and the mechanism of interaction inside the body.

Assessment of Typical Heavy Metals in Human Hair of Different Age Groups and Foodstuffs in Beijing, China

Human hair of different age groups and foodstuff samples were collected in Beijing, China. The concerned metals—Cd, Cr, Pb, As, and Hg—were analyzed, and the metal levels in relation to age, gender, and dietary intake were further assessed. Results showed the highest level of the metals was shown by Pb, with an average concentration of 1.557 ± 0.779 mg/kg, followed by Cr (0.782 ± 0.394), Hg (0.284 ± 0.094), As (0.127 ± 0.078), and Cd (0.071 ± 0.032), following a decreasing order of Pb > Cr > Hg > As > Cd, which were all below the upper limit of normal values in China. The heavy metal concentrations varied greatly among different age groups, and higher concentrations for Cd, Cr, Pb, and As appeared in female hair, whereas higher Hg concentration were found in male hair, suggesting that age and gender were not crucial factors for assessing metal concentrations in human hair. The ingestion of cereals and vegetables were the main route by which heavy metals in the environment create hazardous health effects for local inhabitants, but the estimated metal intakes through food consumption were all lower than the proposed limit of Provisional Tolerable Weekly Intake (PTWI), indicating that heavy metals posed no health risks for the inhabitants. Furthermore, little relationship was found between metal intakes and the corresponding metal levels in hair. Nevertheless, the results of this study can be used to analyze the internal heavy metal burden in the resident population of Beijing area and can also serve as reference for further studies.

Hair analysis in health assessment

BACKGROUND

Hair analysis is used for estimation of the nutritional status of individuals. In the present work, a systematic review on the relation between the mineral composition of hair and the physical or mental disorders is discussed. Detailed information of examined populations, methods of sample preparations and analytical techniques are presented.

METHODS

A systematic literature search in four electronic databases Scopus, PubMed, Web of Science and Medline (from 1997 to 2012/01/31) for English language articles was performed. In addition, a reference list and manual search was undertaken.

RESULTS

The following number of studies was included: 66. Most of the authors reported that there exists a correlation between deficiency or excess of some elements in hair and occurrence of some diseases, such as: autism, cancer, hypertension, myocardial infarction, kidney disease and diabetes mellitus. However, not all results were consistent.

CONCLUSIONS

Most of the authors concluded that the profile of hair mineral imbalance might be useful as a diagnostic tool for the early diagnosis of many diseases. However, it seems that there is a need to standardize sample preparation procedures, in particular washing and mineralization methods.