Use of scalp hair as indicator of human exposure to heavy metals in an electronic waste recycling area

Biomonitoring of metals in the blood and urine of waste recyclers from exposure to airborne fine particulate matter (PM2.5)

This is the first systematic investigation of occupational exposure to toxic metals among waste recyclers in municipal waste recycling facilities. Concentrations of heavy metals (HMs) in the blood and urine of exposed recyclers in different jobs were compared to control groups (administrative department), identifying possible work-related and socio-demographic exposure factors. The potential relationship between HMs levels in PM2.5 and HM concentrations in the blood and urine of recyclers was studied for ten elements. Mean concentrations of HMs of recyclers were significantly higher than for the control group. Over 50% of the waste recyclers had HM levels higher than the recommended limits. The study revealed that most of the waste recyclers engaged in a minimum of three tasks, posing a challenge in establishing a correlation between specific tasks and the levels of elements monitored through biomonitoring. Co levels in blood and Fe levels in the urine of waste recyclers have a significant relationship with the increase in daily working hours. Among the variables related to the participant's demographic information, the level of education and monthly income were significantly different compared to the control group. Also, a significant correlation was found between HM levels in PM2.5 personal exposure and recyclers' urine and blood. Management controls include workflow or, in other words, alternate relocation of workers exposed to severe risks. Engineering controls such as ventilation systems, applying appropriate personal protective equipment (PPE), and risk management methods are the implementation cases to reduce exposure.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40201-024-00924-y.

Environmental pollution and health risks to informal workers: Exposure to heavy metals in human hair at Indonesian landfills

The concentration of heavy metals (HMs) in human hair is a bioindicator of environmental pollution over a long period from worker, including the informal worker at landfills. A landfill is where final-stage refuse is deposited, transported, and disposed of solid waste from urban areas. No study has been conducted on heavy metals in landfills and their health impact on informal workers. This study aims to investigate the accumulation of heavy metals over a long period, the effect of toxic metal exposure on the human body, and the health risks informal workers perceive as bioindicators of pollution in landfills. Human hair samples collected from informal workers and urban were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) to measure HMs and human hair certified reference material (CRM) from the national institute for environmental studies, Japan. The sample consisted of individuals who were interviewed and had their hair cut. The total number of respondents in this study was 51 people. The average concentrations of the element heavy metals (µg/g) in informal workers are shown: Pb 4.70, As 0.30, Cd 1.07, Mn 14.58, Co 0.14, Cu 19.31, Fe 73.05, Zn 646.2, and Se 0.65. The results of our study the concentrations of heavy metals were higher than those found for urban residents. In the education level variable, 17.4 % of respondents did not attend school, 50 % attended primary school, and 32.6 % attended junior high school. Gender of respondents, 71.7 % are female, and in the working period, 69.6 % are more than ten years old. An epidemiological study and statistical analysis show the respondents' symptoms & health complaints such as cough, breathlessness, headache, nose irritation, variable mask, duration using a mask, and characteristics of the respondent's significant correlations p-value < 0.05 with a concentration of all metals. These findings show that the HMs have contaminated the environment and entered the human bodies, posing health risks to informal workers in the landfill working area.

Application of nail analysis in human biomonitoring of toxic pollutants: A review

Nail tissue, as a keratinized biomatrix, serves as a valuable indicator of chronic human exposure to toxic pollutants. The analysis of nail samples has emerged as a prominent method for human exposure assessment, primarily due to its non-invasive sampling procedure and ease of sample storage and transportation. This review examines recent applications of nail analysis in human biomonitoring of toxic organic compounds and heavy metals, along with the various pretreatment methods that have been developed. Studies of human nail samples have revealed distinctive patterns in toxic pollutant accumulation. Brominated flame retardants exhibit significant occupational exposure differences, with concentrations reaching 2.20 × 106 ng/g in manufacturing workers compared to 67 ng/g in the general population. Organophosphate esters demonstrate notable regional variations, as evidenced by Triphenyl phosphate concentrations of 19.6 ng/g in China versus 770 ng/g in the United States. Additionally, the detection of organic pollutant metabolites in nails provides direct evidence of internal exposure. The 5-14 months detection window characteristic of nail samples enables retrospective exposure analysis, highlighting the promising potential of nail analysis in human biomonitoring. Recent developments include the implementation of in situ analytical methods for rapid heavy metal detection in nail samples. However, a significant challenge remains in differentiating between internal and external sources of most compounds in nails, although the identification of metabolic biomarkers for certain pollutants can minimize external interference and better reflect actual body burden. Further research is required to elucidate the relationships between nail pollutant levels, environmental exposure, and health effects. While existing studies demonstrate the considerable potential of nail analysis in human biomonitoring of toxic pollutants, additional research is necessary to validate and fully realize its practical applications.

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.

Revealing the links between hair metal(loids) and alterations in blood pressure among children in e-waste recycling areas through urinary metabolomics

Hypertension is prevalent in e-waste recycling areas, and elevated blood pressure in children significantly increases the risk of hypertension in adulthood. However, the associations and toxic pathways between chronic exposure to metal(loids) and elevated blood pressure are rarely investigated. In this study, we measured the levels of 29 hair metal(loids) (chronic exposure biomarkers) and blood pressure in 667 susceptible children from an e-waste recycling area to explore their relationships. Paired urine metabolomics analysis was also performed to interpret potential mechanistic pathways. Results showed that the hypertension prevalence in our recruited children (13.0 %) exceeded the average rate (9.5 %) for Chinese children aged 6-17 years. The top five abundant metal(loids), including lead, strontium, barium, and zinc, demonstrated the most profound associations with elevated systolic blood pressure. Quantile g-computation, weighted quantile sum, and Bayesian kernel machine regression analysis jointly demonstrated a significant association between chronic exposure to metal(loids) mixture and systolic blood pressure. Interestingly, selenium showed significant antagonistic interactions with these four metals, suggesting that supplementing selenium may help children resist the elevated blood pressure induced by metal(loids) exposure. Increased metal(loids) and blood pressure levels were significantly linked to changes in urine metabolomics. Structural equation model indicated that androsterone glucuronide and N-Acetyl-1-aspartylglutamic acid were the significant mediators of the associations between metal(loids) and blood pressure, with mediation effects of 77.4 % and 29.0 %, respectively, suggesting that androsterone glucuronide and N-Acetyl-1-aspartylglutamic acid may be involved in the development of metal-induced blood pressure elevating effect. Girls were more vulnerable to metal(loids)-induced hormonal imbalance, especially androsterone glucuronide, than boys. Chronic exposure to metal(loids) at e-waste recycling sites may contribute to elevated blood pressure in children through disrupting various metabolism pathways, particularly hormonal balance. Our study provides new insights into potential mechanistic pathways of metal(loids)-induced changes in children's blood pressure.

Human Exposure to Heavy Metals over the Last 100 Years

The primary objective of the presented research was to assess the impact of intense global economic development, over the last 100 years, on the bioaccumulation of heavy metals in the human body. This evaluation was conducted based on the measurement of heavy metals in human hair samples collected 100 years ago in present-day southern Poland.In this study, concentrations of lead (Pb), cadmium (Cd), arsenic (As), zinc (Zn), copper (Cu), iron (Fe), and selenium (Se) were measured in 61 hair samples,28 of which were obtained from individuals who lived 100 years ago, while the remaining 33 constituted the contemporary control group. The concentrations were determined using a triple quadrupole inductively coupled plasma mass spectrometer (Agilent 8900). Statistical analysis of the obtained results was conducted using the Principal Cmponent Analysis and the non-parametric Mann-Whitney test. In the case of As, Pb, Cd, and Fe, the concentrations were significantly higher in individuals who lived 100 years ago compared to those living today. Over this period, the median concentrations were shown to have decreased by 95%, 94%, 85%, and 69% for As, Pb, Cd, and Fe, respectively. No statistically significant differences were observed for Cu, Zn, and Se. The results obtained for Pb, Cd, As, and Fe unequivocally indicate that the population studied from 100 years ago was more exposed to internal contamination with these metals than people who live nowadays.

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.

Serum Levels of Copper and Zinc and Survival in Breast Cancer Patients

There is emerging interest in the relationship between several serum micronutrients and the prognosis of patients with breast cancer. The relationship between serum zinc and copper levels and breast cancer prognosis is unclear. In our study, we included 583 patients with breast cancer diagnosed between 2008 and 2015 in the region of Szczecin, Poland. In a blood sample obtained before treatment, serum zinc and copper levels were quantified by mass spectroscopy. Each patient was assigned to one of four categories (quartiles) based on the distribution of the elements in the entire cohort. Patients were followed from diagnosis to death over a mean of 10.0 years. The 10-year overall survival was 58.3% for women in the highest and 82.1% for those in the lowest quartile of serum copper/zinc ratio (p < 0.001). The multivariate hazard ratio (HR) for breast cancer death was 2.07 (95% CI 1.17-3.63; p = 0.01) for patients in the highest quartile of serum copper/zinc ratio compared to those in the lowest. There is evidence that the serum zinc level and copper/zinc ratio provide an independent predictive value for overall survival and breast cancer-specific survival after breast cancer diagnosis.

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.

Prenatal Exposure to Heavy Metals and Adverse Birth Outcomes: Evidence From an E-Waste Area in China

Electronic waste that has not been properly treated can lead to environmental contamination including of heavy metals, which can pose risks to human health. Infants, a sensitive group, are highly susceptible to heavy metals exposure. The aim of this study was to investigate the association between prenatal heavy metal exposure and infant birth outcomes in an e-waste recycling area in China. We analyzed cadmium (Cd), chromium (Cr), manganese (Mn), lead (Pb), copper (Cu), and arsenic (As) concentrations in 102 human milk samples collected 4 weeks after delivery. The results showed that 34.3% of participants for Cr, which exceeds the World Health Organization (WHO) guidelines, as well as the mean exposure of Cr exceeded the WHO guidelines. We collected data on the birth weight (BW) and length of infants and analyzed the association between metal concentration in human milk and birth outcomes using multivariable linear regression. We observed a significant negative association between the Cd concentration in maternal milk and BW in female infants (β = -162.72, 95% CI = -303.16, -22.25). In contrast, heavy metals did not associate with birth outcomes in male infants. In this study, we found that 34.3% of participants in an e-waste recycling area had a Cr concentration that exceeded WHO guidelines, and there was a significant negative association between prenatal exposure to the Cd and infant BW in females. These results suggest that prenatal exposure to heavy metals in e-waste recycling areas may lead to adverse birth outcomes, especially for female infants.

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.

Heavy metals in fish, rice, and human hair and health risk assessment in Wuhan city, central China

The current study investigated the concentration of heavy metals (HMs) in human hair associated with fish and rice consumption in Wuhan City, central China. The mean values of As in 8/10 fish species exceeded the food safety standard of 0.015 mg/kg. The mean values (mg/kg) of HMs in rice followed a descending order of Zn (13.7)> Cu (1.9)>Cr (0.51)>As (0.11) >Cd (0.08) >Pb (0.04). The ascending order of HMs for male hair was Cd < As < Cr < Pb < Cu < Zn, while As < Cd < Cr < Pb < Cu < Zn for female. 30% of hair Cr and 22% of hair Zn contents exceeded the recommended values. The middle age (19-44) and adult (45-59) groups were the most vulnerable group, as the concentration for most elements was high in these age groups. A significant correlation was found between fish-eating frequency and hair Zn (r = 0.213; p < 0.05), and As (r = 0.204; p < 0.05). High odd ratios were found in a population with high fish-eating frequency, especially for Pb (7.19), As (3.1), Zn (3.83), and Cd (3.7). A significant non-carcinogenic risk was associated with Cr exposure through consuming herbivores, filter feeders, and omnivorous fish. The cancer risk values of Cd exposure (1.54E-04) via rice consumption and As exposure (1.25E-04) via consumption of omnivores fish indicate precautionary measures.

Heavy metals in paired samples of hair and nails in China: occurrence, sources and health risk assessment

The occurrence of heavy metals including chromium (Cr), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd) and lead (Pb) was investigated in paired samples of hair and nails collected from 121 volunteers in 16 cities, China. Results showed that the mean concentrations of Zn, Cu, As, Pb, Cr, Ni and Cd were 205, 18.0, 7.79, 6.18, 3.54, 2.02, 0.533 μg g^-1 in hair and 103, 8.09, 0.760, 7.27, 6.07, 8.81, 0.485 μg g^-1 in nails, respectively. The concentrations of Zn, Ni, Cr, Cd and Pb were positively correlated in paired samples of hair and nails, whereas a negative correlation was found for Cu and As between hair and nails. Higher concentrations of heavy metals were found in northern China than southern China. The multivariate analysis of variance revealed that dwelling environment was the dominant factor influencing the levels of Cd in hair (p < 0.05), while age was the dominant factor influencing the levels of Cr in nails (p < 0.05). Moreover, industrial pollution and smoking were also the important factors leading to the accumulation of heavy metals in human body. Principal component analysis (PCA) showed that industrial pollution and decoration material immersion were the main factors for the high concentrations of Cr and Ni in hair, accounting for 62.9% of the total variation; As in hair was dominantly related to groundwater pollution. The concentrations of heavy metals were within the recommended ranges in nails from this study. However, the mean levels of Cr, Ni and As in hair exceeded their recommended reference values, indicating potential health risks from heavy metals for residents in China.

Impact of prenatal exposure to metallic elements on neural tube defects: Insights from human investigations

Metallic elements play a pivotal role in maternal and fetal health. Metals can cross the placental barrier and be absorbed by fetuses, where they may affect closure of the neural tube during embryonic development. Neural tube defects (NTDs), which result from aberrant closure of the neural tube three to four weeks post-conception, have a multifactorial and complex etiology that combines genetic variants and environmental exposure. Recent advances in population-level association studies have investigated the link between maternal environmental exposure and NTDs, particularly the influence of metals on the incidence of NTDs. Herein, we present a broad and qualitative review of current literature on the association between maternal and prenatal metal exposure via the maternal peripheral blood, amniotic fluid, placenta, umbilical cord, and maternal hair, and the risk of developing NTDs. Specifically, we identify the various aggravating or attenuating effects of metallic exposure on the risk of NTD formation. This review provides novel insights into the association between environmental metals and NTDs and has important applications for NTD prevention and mitigating environmental exposure to metals.

Survey to identify the metal accumulation pathway in humans using hair and nail as biomarkers from fisherfolk population

Human hair and nail samples from Cuddalore fisherfolk populations were used as biomarkers for assessing metal concentrations in humans. Hair samples from 80 participants (47 men and 33 women) and nail samples from 40 participants (21 men and 19 women) were collected, and the concentrations of Cd, Cu, Pb, and Zn were assessed using an atomic absorption spectrophotometer (AAS). Metal data from AAS were compared with the survey questionnaire's personal and dietary parameters. Results indicate that both personal and dietary parameters may influence metal exposure; however, majority of the sources may have originated from metal-contaminated seafood. Higher metal accumulation in communities, especially those which consume seafood on a daily basis, may increase the possibility for them to get affected by metal-related diseases. Based on environmental parameters, people who live ≤500 m from industrial zones accumulate more metals. Further extensive studies with more individuals and more questionnaire parameters are needed to identify the metal accumulation pathway in humans.

Tracking cadmium pollution from source to receptor: A health-risk focused transfer continuum approach

Cadmium (Cd) exposure poses a substantial risk to human health. Despite this, the multi-stage process through which Cd is released to the environment before being taken up and impacting human receptors has rarely been investigated. Here we utilized an integrated model involving Cd emissions, atmospheric transport, deposition, uptake by rice, receptor ingestion and metabolic processing in quantifying the critical emission sources and human health risks of Cd. Atmospheric Cd emissions in the study area in southeastern China were estimated at 147 kg (2016), with >53 % of emissions from non-ferrous metals (NFM) smelting activities. Atmospheric Cd depositions caused elevated Cd content in soil and rice, accounting for 3-79 % and 50-85 % of, respectively, soil and rice Cd. Cumulative frequency analysis showed that an estimated 1.3 % of predicted urine Cd through the consumption of Cd-contaminated rice and exceeded existing safety standards (1 μg g^-1), thus highlighting the risks posed to health from high levels of Cd pollution. Applying stricter industrial emission standards to the NFM sector in particular and effective soil management practices could substantially reduce exposure to Cd pollution. The results contribute to understanding of the Cd transfer process and draw attention to the relative health benefits of interventions aimed at mitigating Cd levels and exposure risks at different stages along the Cd transfer continuum from source to receptor.

Distribution Characteristics and Influencing Factors of Bio-elements in the Human Hair of Uyghur Communities in an Oasis Area of Xinjiang, China

Located in central Asia, Xinjiang is characterized as a diverse environment in China, consisting of vast deserts, dotted oases, and high mountains. Due to the combined effect of climate conditions under such a diverse environment, there are large differences in human activities, living styles, and eating habits in farmland and grazing pastures between Xinjiang and other regions of China. This study aimed to investigate the variations and mechanisms of elemental distribution in the hair of Uyghur communities among different ages and genders and under different land use backgrounds in an oasis region in Xinjiang. Hair samples from 524 residents from four traditional farmland areas and two grazing pasture areas in Bai Cheng County in Xinjiang were collected, and the levels of thirteen elements were analyzed. The results indicated that the average levels of Cu, Mg, Mn, Zn, Ni, Co, Pb, Fe, Ca, Cd, Cr, As, and Se in the hair of Uyghur communities were within the background levels of Chinese and global residents' hair. Overall, the levels of elements in the hair of women residents were higher than those of men residents. The levels of elements in the human hair of the middle-aged group were higher than those of child and older-aged groups. Elements Cr and Se in the hair of grazing pastures were higher than those of farmland areas. The levels of Cd, Pb, As, and Zn in the hair of farmland areas were higher than those of grazing pasture areas. The levels of Ca, Mg, Cu, and Fe in the hair of Uyghur communities were higher than those of other ethnic groups, while the toxic elements in the hair of residents in Bai Cheng were lower than those in other regions of China. Middle-aged people were exposed to higher levels of toxic elements in their daily activities compared to elderly and child groups. Also, adult groups need much more nutrients for their growth and intellectual development compared to child and elderly groups. The change in land use from grazing pastures to farmland increased the toxic trace element concentration levels in human hair. The significant differences in the overall concentration levels of elements in human hair among the different ethnic groups and regions can be attributed to the differences in lifestyles, cultural customs, dietary habits, and internal and external exposure routes.

E-waste dismantling as a source of personal exposure and environmental release of fine and ultrafine particles

Electronic waste (WEEE; from TV screens to electric toothbrushes) is one of the fastest growing waste streams in the world. Prior to recycling, e-waste components (metals, wood, glass, etc.) are processed by shredding, grinding and chainsaw cutting. These activities generate fine and ultrafine particle emissions, containing metals as well as organics (e.g., flame retardants), which have high potential for human health impacts as well as for environmental release. In this work, release of fine and ultrafine particles, and their exposure impacts, was assessed in an e-waste recycling facility under real-world operating conditions. Parameters monitored were black carbon, particle mass concentrations, ultrafine particles, and aerosol morphology and chemical composition. Potential health impacts were assessed in terms of cytotoxicity (cell viability) and oxidative stress (ROS) on <2 μm particles collected in liquid suspension. Environmental release of WEEE aerosols was evidenced by the higher particle concentrations monitored outside the facility when compared to the urban background (43 vs.11 μgPM2.5/m³, respectively, or 2.4 vs. 0.2 μgCa/m³). Inside the facility, concentrations were higher in the top than on the ground floor (PM2.5 = 147 vs. 78 μg/m³, N = 15.4 ∗ 104 vs. 8.7 ∗ 104/cm³, BC = 12.4 vs. 7.2 μg/m³). Ventilation was a key driver of human exposure, in combination with particle emissions. Key chemical tracers were Ca (from plastic fillers) and Fe (from wiring and other metal components). Y, Zr, Cd, Pb, P and Bi were markers of cathode TV recycling, and Li and Cr of grinding activities. While aerosols did not evidence cytotoxic effects, ROS generation was detected in 4 out of the 12 samples collected, associated to the ultrafine fraction. We conclude on the need for studies on aerosol emissions from WEEE facilities, especially in Europe, due to their demonstrable environmental and human health impacts and the rapidly growing generation of this type of waste.

Associations between hair levels of trace elements and the risk of preterm birth among pregnant Wwomen: A prospective nested case-control study in Beijing Birth Cohort (BBC), China

Trace elements have various physiochemical functions in humans and are associated with the occurrence of preterm birth (PB). However, their mixed effects on PB risk have rarely been studied. We aimed to investigate the associations between hair levels of trace elements and PB risk among pregnant women. A nested case-control study with a prospective cohort was conducted in Beijing City, China. We included 82 women who had a PB [total PB (tPB)] as cases [including 40 with a spontaneous PB (SPB)] and 415 who had a term delivery as controls. Hair levels of the concerned trace elements were measured including endocrine disrupting metal(loid)s [EDMs; lead, mercury (Hg), arsenic, and cadmium] and nutritional trace metal(loid)s [NTMs; zinc (Zn), iron (Fe), copper, and selenium]. Logistic regression analysis was performed to estimate the odds ratios (ORs) for PB. Bayesian kernel machine regression (BKMR) was used to assess the associations between mixed exposure to the trace elements and PB risk. Significantly lower maternal hair concentrations of Zn and Fe were observed in the SPB cases than in the controls, whereas no differences for the other trace elements. Single-element modeling results suggested second-quartile Hg maternal hair concentrations, third-quartile Zn concentrations, and fourth-quartile Fe concentrations were associated with a reduced risk of tPB with adjusted ORs of 0.43 [95% confidence interval (CI): 0.21-0.87], 0.38 (95% CI: 0.18-0.82), and 0.48 (95% CI: 0.24-0.98), respectively, compared to first-quartile values. Similar results were obtained for SPB. According to the BKMR models, hair NTMs were significantly, monotonously, and inversely associated with the risk of SPB, after controlling for covariates and levels of the four EDMs. Fe and Zn contributed the most strongly to the association. We concluded that maternal higher levels of NTMs, especially Fe and Zn, may reduce the risk of PB.

Cadmium and Lead Pollution Characteristics of Soils, Vegetables and Human Hair Around an Open-cast Lead-zinc Mine

Atmospheric deposition of cadmium (Cd) and lead (Pb) was investigated together with the accumulation, distribution and health risks from potentially toxic metals in soils, vegetables and human hair at a mining area in southwest China. Annual atmospheric deposition of Cd and Pb were 41.1 and 192 g ha^- 1, respectively, and consisted mainly of dry deposition. Agricultural soils experienced high levels of metal pollution around the mine, with 66.4% and 57.3 % of vegetable samples grown on these polluted fields exceeding maximum permissible Cd and Pb concentrations, particularly the leafy vegetables. Residents living near the mining area had high Cd (0.75 mg kg^- 1) and Pb (6.87 mg kg^- 1) concentrations in their hair, and the maximum values occurred in occupationally exposed individuals. Long-term mining activities have resulted in high health risks to the local population due to Cd and Pb deposition and accumulation from the atmosphere, soils and vegetables.

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.

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.

Direct Ultratrace Detection of Lead in a Single Hair Using Portable Electromagnetic Heating Vaporization-Atmospheric Pressure Glow Discharge-Atomic Emission Spectrometry

In this paper, the first demonstration of direct ultratrace determination of lead in a single human hair by direct current-atmospheric pressure glow discharge-atomic emission spectrometry (DC-APGD-AES) coupled with electromagnetic heating vaporization (EMV) was described. Only the ultramicro mass of a human hair sample (about 0.15 mg, often a single human hair) was required during the analysis, and fast detection was implemented without tedious pretreatment processes, such as grinding and digestion. A limit of detection (LOD) of 30.8 μg kg^-1 (4.8 pg) for Pb was obtained under optimized conditions, which was even equivalent to that of conventional LA-ICP-MS/ETV-ICP-MS/GFAAS. EMV-APGD-AES, meanwhile, can facilitate miniaturization and portability with low power and small size. The accuracy and practicality of the method were verified by the analysis of certified reference materials (CRMs) GBW09101b (human hair) and human hair samples from three volunteers. A simple, efficient, and low-cost method for detecting Pb in human hair has been developed.

Research trends and frontiers on source appointment of soil heavy metal: a scientometric review (2000-2020)

In recent years, source appointment of soil heavy metal has attracted growing attention. However, few studies have attempted to make a comprehensive and systematical review on this topic. For this reason, a total of 1051 publications were retrieved from the Web of Science (WOS) database between 2000 and 2020. A scientometric analysis was carried out to reveal the characteristics of publications, research power, and research hotspots. CiteSpace was used to visualize and summarize the information about the development in this field. The results showed that (1) the number of publications in source appointment of soil heavy metal had increased rapidly; Environmental science and ecology and environmental sciences were top 2 most popular subject categories; (2) Research power was mainly distributed in Asia, Europe, and North America. China and Chinese Academy of Sciences were the most productive country and institution in terms of publications in this field. Biao Huang (China) was the most productive author. However, Hakanson L (Sweden) was the most influential author in terms of citation frequency; (3) Heavy metal, source identification, and contamination were the most frequent keywords. Keyword clustering analysis showed that the research hotspots mainly concentrated on air pollution, bioremediation, spatial distribution, soil, PCA, and so on; (4) Keyword bursts analysis showed that the research frontiers mainly focused on spatial analysis of soil heavy metal and exposure risk to human health.

Levels, Spatial Distribution, and Impact Factors of Heavy Metals in the Hair of Metropolitan Residents in China and Human Health Implications

Chronic exposure to low levels of heavy metals threatens human health. However, few studies evaluated the health effects and spatial distributions of chronic exposure to heavy metals in metropolitan residents throughout mainland China using unified sampling methods and evaluation indicators at the national level. Here, the concentrations and spatial distributions of heavy metals (As, Cd, Cr, Sb, Pb, and Hg) in the hair of 1202 metropolitan residents from mainland China were analyzed, and differences in age and sex were evaluated. Most target metals exhibited higher concentrations in the hair of residents from South Central China. Generally, male hair had higher As and Se concentrations, whereas female hair had higher Cd and Pb levels (p < 0.05). A significant pairwise correlation existed between most metals in hair, especially Cd-Pb (r = 0.638, p < 0.05). The Se/heavy metal molar ratio is used as an indicator to assess the detoxification ability. The results demonstrated that protecting metropolitan residents in South Central China from heavy metals in their daily life is crucial, particularly for Hg, Pb, and Cr with Se/(Hg, Pb, or Cr) molar ratios < 1. This is the first study to comprehensively consider the antagonistic effects of Se and heavy metals using the molar ratio of Se/heavy metals to evaluate health implications and propose health management policies for metropolitan residents in China.

Exposure of street sweepers to cadmium, lead, and arsenic in dust based on variable exposure duration in zinc smelting district, Northeast China

Street dust is an important contributor to heavy metal exposure in street sweepers. In this work, the levels of cadmium (Cd), lead (Pb), and arsenic (As) in street dust were evaluated, and the corresponding health implications for street sweepers in the smelting district of Huludao city northeast China were assessed. The contributions of dietary sources and dust to total metal exposure in street sweepers were compared. Because street sweepers are exposed to street dust both during work and nonwork hours, the health risks faced by street sweepers are uncertain. Therefore, variable exposure duration was considered using a deterministic model. A probabilistic risk assessment model was developed to explore the health effects of street dust on street sweepers via Monte Carlo simulation. The various exposure parameters that affect risk were analyzed using sensitivity analysis. The average Cd, Pb, and As levels in the hair of street sweepers were 2.04, 20.12, and 0.52 mg·kg^-1, respectively. These values were higher than those for residents (i.e., not street sweepers) of Huludao. Strong correlations were found between the logarithms (base 10) of the Cd, Pb, and As contents in dust and hair (r_Cd = 0.581, p < 0.01; r_Pb = 0.428, p < 0.01; r_As = 0.378, p < 0.01; n = 62). Based on analysis using deterministic models, the maximum exposures to Cd and Pb via dust through the alimentary canal were nearly three and six times higher than the dietary exposures, respectively. Sensitivity analysis indicated that exposure duration is an important parameter.

Cumulative Effect and Content Variation of Toxic Trace Elements in Human Hair around Xiaoqinling Gold Mining Area, Northwestern China

The harm of toxic trace element polluted living environments to human health in mining areas has attracted extensive attention. In this study, human hair samples from a toxic trace element polluted area (village A) in a mineral processing area collected in 2015 and 2019 were studied in detail and the nonpolluted human hair samples from a contrast area (village B) with a relatively clean environment were also collected for comparison. The Hg and As in human hair samples were analyzed by Atomic Fluorescence Spectrometry (AFS) and the Pb, Cd, Cr, and Cu in human hair samples were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The single cumulative index (P_i) and the Nemerrow index (P_z) were used to evaluate the single and comprehensive cumulative pollution index. The results indicated that the average toxic trace element contents in human hair from different ages in the polluted area exhibited certain statistical significance. The average single cumulative indexes indicated a significant accumulation of Hg, Pb, and Cd in human hair of both genders and different ages from the polluted area, and the comprehensive cumulative pollution indexes revealed higher accumulation of toxic trace elements in the hair of males than in females. In general, the content of toxic trace elements in human hair from polluted area was still growing in accumulation. The high content of toxic trace elements in human hair shows a notable correlation with human health, and the environmental pollution in gold mining areas is seriously harmful to human health.

Assessment of some heavy metals in crude oil workers from Kurdistan Region, northern Iraq

Heavy metal pollution in the environment has gained interest in the past few decades, as it has been found to accumulate in soil and water, as well as in the human body. Heavy metals present a serious health risk to humans when the concentration level and exposure time are increased. Although they have been extensively studied in the environment and food, little is known regarding their occurrence in the Kurdistan Region of northern Iraq. To fill this gap, we investigated the occurrence of some metals and heavy metals, namely aluminium (Al), barium (Ba), mercury (Hg), manganese (Mn), lead (Pb), vanadium (V) and zinc (Zn), in the blood of crude oil workers (40 men) who have worked in crude oil fields for at least 3 years-exposed group. In addition, a control group of 40 men was selected who have never worked or been close to crude oil fields. There is a significant correlation of metal concentrations between exposed and control groups, especially for Al, Ba, Hg, Mn and V (significant for all metals). Even though the correlation for Pb and Zn was weak, the concentrations were higher by 2-folds in the exposed group compared to the control group. Thus, the exposure caused an increase in the concentration of heavy metals by at least 1-fold in the blood of the exposed group compared to the control group. The environmental and ecotoxicological relevance of heavy metals in humans and the environment in areas with industrial activities have yet to be assessed.

Quantifying the Deposition of Airborne Particulate Matter Pollution on Skin Using Elemental Markers

Airborne particulate matter (PM) pollution is an environmental and health concern. The health impact of PM pollution has typically focused on the respiratory system. The impact of PM pollution on skin has been largely understudied due to the lack of a quantitative method to measure the deposition on skin. This manuscript presents a method to quantify PM pollution on skin using elemental markers as a proxy for PM. Skin tape strips were collected from forehead and buttock of 100 outdoor workers in Beijing, China. Skin samples were analyzed for 19 elemental markers using inductively coupled plasma mass spectrometry. To determine the specific elemental signature of PM for the region, air samples were collected over 7 days for PM < 2.5 μm (PM_2.5) and analyzed for the same 19 elements as the skin samples. An enrichment factor was calculated for each element and the potential source was evaluated. Using the elemental markers unique to PM pollution for the region, the PM concentration deposited on skin was determined to be 0.621-2.53 μg PM_2.5 /cm². This method can be re-applied in different regions and the PM concentration on skin can inform future studies on the health impact of air pollution on skin.

Chronic exposure to heavy metals from informal e-waste recycling plants and children's attention, executive function and academic performance

E-waste contains valuable metals that require appropriate waste management plans. However, rudimentary e-waste processing methods are a source of heavy metals environmental pollution. This study has characterised concentrations of heavy metals in soil (n = 10), water (n = 10) and hair (n = 44) of children in areas surrounding Jakarta (Indonesia), where e-waste is being or has been conducted in the past, and in a reference unexposed site. Chronic exposure to Mn, Pb, Hg, As and Cd and its associations with attention and executive function, characterised with the Trail Making Test (TMT), along with academic performance scores was conducted using multivariate regression analysis. Models were adjusted for age, gender, parental education, environmental tobacco smoke and residential traffic. Lead (3653 ± 3355 mg/kg), cadmium (3.4 ± 0.9 mg/kg) and mercury (15.2 ± 28.5 mg/kg) concentrations from soil and manganese concentrations in water (1.43 ± 0.64 mg/L) in the exposed sites were higher than current regulations. Heavy metal concentrations in hair of children living near e-waste facilities was higher than for children living in non-exposed areas (Pb: 0.155 ± 0.187 vs 0.0729 ± 0.08 mg/g; Mn: 0.130 ± 0.212 vs 0.018 ± 0.045 mg/g; Hg: 0.008 ± 0.0042 vs 0.002 ± 0.0011 mg/g) suggesting chronic exposure to heavy metals. Manganese exposure was associated with worse cognitive performance in the domains of attention (TMT-A score: 66 s, 95% CI 0.09, 132), executive function (TMT-B score: 105 s, 95% CI 11.5, 198) and social sciences (-29%, 95% CI -54, -4.7) (per unit of Mn in hair mg/g). These results suggest that informal e-waste activities contribute to local heavy metal soil contamination, and could be an important source of metal exposure to children living in the vicinity of these facilities with putative impacts on their cognitive performance. E-waste management regulation and remediation programmes should be implemented to reduce environmental pollution and associated health effects.

External interference from ambient air pollution on using hair metal(loid)s for biomarker-based exposure assessment

Hair metal(loid)s are often measured as biomarkers to evaluate population internal exposure, however, hair samples could be easily contaminated by ambient particulate matter (PM) pollution. Here, we evaluated the potential external interference from ambient PM pollution on using hair metal(loid)s for population biomarker-based exposure assessment. The raw hair samples were strictly washed and placed under various indoor and outdoor scenarios for ~6 months at sites with high PM pollution. The contaminated hair was then washed using the same method. A total of 33 hair elements were quantified by inductively coupled plasma-mass spectrometry. The surface residual PM on hair after washing was observed by scanning electron microscopy. In addition, we chose a practical exposure scenario including 77 housewives in Shanxi Province, China for validation. The results for the hair exposure experiment revealed that external contamination of some elements that had relatively high concentrations in hair was generally mild in both indoor and outdoor exposure scenarios (i.e., Zn, Mg, Se, Fe, Sr, Ti, Mn, Sn, Ge, U, Co, Mo, and As). A relatively higher external contamination of other elements (e.g., Al, Cr, Pb, Cd, Li, and most rare earth elements (REEs)) was observed, especially for those elements with relatively low hair concentrations (e.g., Cd, and REEs) in the outdoor environment. This finding was due mainly to some small ambient PM not being fully removed by the current washing strategy when the hair sample was heavily contaminated. However, results from practical exposure scenario of the housewives showed that there were overall no significant differences of hair metal(loid)s between the housewives using coal and clean energy for cooking. We concluded that the external interference on hair internal metal(loid) analysis could be negligible when hair was efficiently washed, especially for population with relatively longer indoor activities. It is therefore promising to use hair analysis for their population exposure assessment.

Associations of exposure to metals with the risk of hypertension among an older population aged 40-75 years in rural southwest China

Metal exposure has recently been related to the risk of hypertension. However, the association remains unclear and relevant epidemiologic studies are limited. The present study aimed to assess the associations between exposure to metals and the odds of hypertension, as well as blood pressure (BP) levels. A total of 816 participants were enrolled in southwestern China. Hypertension was defined as a systolic BP (SBP) of ≥140 mmHg or diastolic BP (DBP) of ≥90 mmHg, a self-reported physician diagnosis, or current use of antihypertensive medication. Blood samples were used to detect the levels of exposure to metals, ie, magnesium (Mg), calcium (Ca), iron (Fe), zinc (Zn), arsenic (As), cadmium (Cd), copper (Cu) and lead (Pb). Logistic and linear regression models were used to assess the potential associations. The results show that positive trends for elevated odds of hypertension with increasing quartiles of Fe in a polluted area; and of Mg, Ca and Cu in an unpolluted area. Compared with those in the lowest quartiles, participants in the highest quartiles of Fe, Mg and Ca had 2.7-, 9.0- and 5.1-fold increased odds of hypertension, respectively. High blood Fe and Pb levels in the Cd-polluted area, and Mg and Fe in the unpolluted area were found to be related to increasing SBP and DBP levels. Our findings suggest that exposure to Fe and/or Pb in the polluted area; and Mg, Ca and Fe in the unpolluted area might increase the risk of hypertension or elevate BP levels.

Metallic elements in human hair from residents in smelting districts in northeast China: Environmental factors and differences in ingestion media

The health of residents in Huludao City is affected by the emissions of heavy metals from smelting, diet and atmospheric precipitation. This study investigated the concentrations of Hg, Cd, Pb, Cu and Zn in scalp hair samples from 259 residents of different ages and genders from five districts in Huludao City and examined the main factors for heavy metal exposure. Cd and Pb concentrations in hair samples exceeded the normal concentration ranges for human hair (Cd < 0.3 mg/kg; Pb < 9.3 mg/kg), and the highest Pb concentrations were found in subjects in the age range 0-15 years. Samples from men were higher in Cd and Pb compared to those for women. Workers from the Huludao zinc plant (HZP) had higher concentrations of all metals in their hair relative to other occupations except for Cu. Geographically, the highest Cd and Pb concentrations in hair were found for residents living in Daochi district (DCD) and the Zn plant district (ZPD), respectively. In smelting regions, the effects of dust ingestion on heavy metal exposure were more important than in non-smelting regions.

The Interaction Between Concentration of Heavy Metal-Trace Elements and Non-Smoking Status of Adolescents in Sinop (Turkey)

This study was experimentally conducted between 2017 and 2018 in order to determine the interactions of heavy metals and non-smoking status of adolescents in Sinop Province (Turkey). In this regard, the students of Sarı Saltuk Anatolian High School students in Sinop Province were examined. The research data was obtained using a questionnaire, including questions about sociodemographic characteristics and smoking status of the adolescences. Afterwards, 0.5 g of hair samples from 40 female students who accepted to participate to the research was collected and analyzed by inductively coupled plasma mass spectrometry (ICP-MSMS), and the obtained data were evaluated using SPSS (version 22.0) statistical program. At the end of the study, the Mg, Cr, Co, and Zn elements of the non-smoking girls were found to be slightly higher than the normal range of hair, and the high concentration of Cd element was related to the contamination by passive smoking. Besides, it was determined that the elements which showed the highest positive correlation in hair samples taken from the children of smokers were Ca/Cd, Al/Fe, Mg/Cr, Na/Fe, Al/Cd, and Al/Na, respectively. As the nursing approach, it is thought that trainings aiming to prevent smoking and quitting smoking are extremely important.

Lead smelting effects heavy metal concentrations in soils, wheat, and potentially humans

Cadmium, Cu, Pb and Zn concentrations and distribution in soil, wheat, and the potential for human heavy metal accumulation near a Pb smelting affected area were investigated. Farm land soil, wheat grain and scalp hair samples were collected from three villages (named QD, GF and BS) with increasing distance from a large Pb smelter in China. Soil Cd and Pb concentrations exceeded national standards 46-100% of the time, depending on location. Soil and wheat grain Cd, Cu, Pb and Zn concentrations increased as distance to the smelter decreased. Similarly, greater Cd, Cu and Pb concentrations were present in human scalp hair for those residents living closest to the smelter. Decreasing trends existed for hair-to-wheat grain ratios for Cd and Pb as distance to the smelter increased. Results suggest that as distance to the smelter decreases, human heavy metal absorption via the consumption of metal-contaminated food products (e.g., wheat) increases.

Associations of plasma metal concentrations with the decline in kidney function: A longitudinal study of Chinese adults

Metals are widespread pollutants in the environment which have been reported to be associated with kidney dysfunction in many existing epidemiological studies. However, most of the studies are cross-sectional design and mainly focus on several toxic metals including arsenic, lead and cadmium. Therefore, we conducted this prospective study within the Dongfeng-Tongji cohort to evaluate the associations of plasma multiple metals with the decline in kidney function among Chinese middle-aged and elderly. In total, 1434 participants free of chronic diseases at baseline were included in analysis. We measured baseline plasma concentrations of 23 metals and calculated estimated glomerular filtration rate (eGFR) using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation based on serum creatinine, age, sex and ethnicity. Bonferroni correction was used for multiple testing to reduce the probability of a type I error. Principal component analysis was conducted to evaluate the combined effect of multiple metal co-exposure. Most of the plasma metal concentrations were within the literature reported reference values, whereas the concentration of lead and nickel exceeded the guideline value. We found that plasma concentrations of aluminum, arsenic, barium, lead, molybdenum, rubidium, strontium, vanadium and zinc were significantly associated with the decline in kidney function measured by annual eGFR decline, rapid renal function decline (defined as an annual decline in eGFR ≥ 5 mL/min/1.73 m²) or incident eGFR < 60 mL/min/1.73 m², with the adjusted beta coefficients (95% CI) for annual eGFR decline 0.50 (0.30, 0.69), 0.98 (0.74, 1.23), 0.56 (0.32, 0.79), 0.21 (0.03, 0.39), 0.35 (0.16, 0.54), 0.94 (0.71, 1.17), 0.37 (0.15, 0.60), 0.78 (0.54, 1.02), and 0.74 (0.57, 0.91), respectively. The metals exposures were linked with increased risks of impaired kidney function. Associations of principal components representing these metals with the decline in kidney function were significant and suggest a possible additional health risk by co-exposure. Participants engaged in manufacturing had higher plasma levels of several metals compared with those who had been involved in management- or administration-related work. Our findings suggest that exposure to multiple metals contribute to the decline in kidney function among the middle-aged and elderly. Co-exposure to multiple metals may have synergetic effect on the kidney function. Further studies are warranted to confirm our findings and clarify the potential mechanisms.

A meta-analysis of zinc levels in breast cancer

BACKGROUND

Breast cancer is the most commonly occurring neoplasm in females, comprising 16% of all female cancers worldwide. Various studies indicate some discrepancies regarding zinc (Zn) levels in various samples of breast cancer patients.

OBJECTIVE

The present study evaluated by meta-analysed the published data for Zn levels analyzed in breast tissue, plasma, serum, and hair samples and its relationship with breast cancer.

METHODS

The present meta-analysis included 36 studies, all of which were published in the years between 1984 to 2017 and selected by searching the databases MEDLINE, EMBASE, Cochrane Library, PubMed, Scopus, and the ISI Web of Knowledge. The articles were analyzed, and I² statistics were used to examine heterogeneity. The objective analysis was performed on data from the 36 studies, with total 1699 study subjects and 2009 controls.

RESULTS

Significant statistical differences overall were observed, based on a random effects model (SMD (95 % CI), -0.78[-1.40, -0.16], P = 0.014). Data from 19 of these studies indicated significant statistical differences between cancerous patients and controls with regard to serum and plasma Zn concentration (SMD [(95 %CI): -1.61(-2.43, -0.79)]. There was a significant statistical difference between the breast tissue and hair as regards Zn status (SMD (95%CI): 2.32(1.42, 3.21)) and (SMD (95v%CI): -1.80(-3.41, -0.20), respectively. Zn concentration levels typically decreased in blood and hair samples of patients with breast cancer, whereas it was elevated in tumor tissues.

CONCLUSIONS

There is a significant relationship between lowered serum Zn concentrations and risk of breast cancer onset or recurrences in women, but because of high heterogeneity, we recommend other primary studies.

Urinary and hair concentrations of trace metals in pregnant women from Northeastern British Columbia, Canada: a pilot study

BACKGROUND

Northeastern British Columbia (Canada) is an area of intense natural gas exploitation by hydraulic fracturing. Hydraulic fracturing can release contaminants, including trace metals, many of which are known developmental toxicants. To date, there is limited data on human exposure to contaminants in this region.

OBJECTIVE

We aimed to examine trace metals in urine and hair samples from 29 Indigenous and non-Indigenous pregnant women from two communities (Chetwynd and Dawson Creek) in Northeastern British Columbia.

METHODS

We recruited 29 pregnant women who provided spot urine samples over five consecutive days and one hair sample. We measured 19 trace metals in pooled urine samples from each participant and in the first 2 cm of hair closest to the scalp. We compared urinary and hair concentrations to those measured in women from the general population using data from the Canadian Health Measure Survey (CHMS), or reference values found in the literature for trace metals not measured in the CHMS.

RESULTS

Median urinary (0.49 μg/L) and hair (0.16 μg/g) concentrations of manganese were higher in our participants than in the CHMS (<0.05 µg/L in urine) or reference population (0.067 μg/g in hair). In hair, median values for barium (4.48 μg/g), aluminum (4.37 μg/g) and strontium (4.47 μg/g) were respectively 16, 3, and 6 times higher compared with median values in a reference population. Concentrations of barium and strontium in hair were higher in self-identified Indigenous participants (5.9 and 5.46 μg/g, respectively) compared to non-Indigenous participants (3.88 and 2.60 μg/g) (p-values = 0.02 and 0.03).

CONCLUSION

Our results suggest higher gestational exposure to certain trace metals in our study population compared to reference populations.

Soil and indoor dust as environmental media of human exposure to As, Cd, Cu, and Pb near a copper smelter in central Chile

In the present study, we assessed the non-carcinogenic and carcinogenic human health risk due to exposure to trace elements in soil and indoor dust in Puchuncaví valley. We also determined the associations between trace element concentration in hair/toenails and the estimated chronic daily intake of trace elements in soil and indoor dust. We found statistically significant association between the trace element concentration in hair/toenails and the estimated chronic daily intake of soil and indoor dust. Indoor dust was more important than soil in terms of human exposure to trace elements in Puchuncaví, due to the high concentration of trace elements on this environmental media and long periods of time that the population spends at their households. With regards to non-carcinogenic risk, we found that there was no health risk associated to soil and indoor dust exposure in the Puchuncaví valley, because none of the hazard quotient values surpassed 1.0. However, carcinogenic risk due to arsenic exposure was above the threshold value of 1.0E-04 in the population of young children (from 1 to 5 years old) in all studied areas, including the control, and in the population of children (from 6 to <18 years old) in the exposed area. Such risk values are classified as unacceptable (US EPA, 2001), requiring some target intervention from the Chilean government.

Association of maternal chronic arsenic exposure with the risk of neural tube defects in Northern China

Numerous animal studies have shown that high arsenic exposure can induce neural tube defect (NTD) formation. However, epidemiological evidence related to this finding is scarce. The key objective of our study is to evaluate whether maternal arsenic exposure is associated with NTD risk in Northern China. Our case-control study was conducted in 11 countries or cities in Shanxi and Hebei provinces during 2003-2007. A total of 774 mothers were included as participants: 511 controls and 263 cases (including 123 with anencephaly, 115 with spina bifida, 18 with encephalocele, and 7 with other NTD subtypes). The arsenic concentration was measured in a specific section of hair that grew from 3 months before to 3 months after conception. We found a higher hair arsenic concentration in the NTD cases with median (inter-quartile range) of 0.093 (0.025-0.387) μg/g hair than that in the controls with a value of 0.082 (0.030-0.414) μg/g hair. Maternal hair arsenic concentration above its median of the controls was associated with an increased risk of the total NTDs with an adjusted odds ratio (OR) of 1.32 [95% confidence interval (CI): (0.91-1.92)], which was not statistically significant (p = 0.14), although the crude OR without adjusting for the confounders of 1.68 (95% CI: 1.24-2.27; p < 0.001) suggested that hair arsenic is a risk factor of NTDs. There was no dose-response relationship between maternal hair arsenic concentration and the risk of total NTDs. Similar phenomena were found for anencephaly and spina bifida, respectively. Overall, our findings showed that maternal periconceptional arsenic exposure may not significantly contribute to the risk of NTD development in Northern China; other risk factors need to be further examined in future studies.

Health risks to local residents from the exposure of heavy metals around the largest copper smelter in China

Non-ferrous smelting releases lots of heavy metals to the environment. Although numerous studies have focused on pollution in the environment, fewer have studied the adverse health effects. In the current study, samples of food, hair and urine were collected and analyzed for zinc (Zn), iron (Fe), chromium (Cr), nickel (Ni), lead (Pb) and copper (Cu) from residents of 3 villages near the largest copper smelter in China. The estimated daily intake (EDI), target hazard quotient (THQ), and Hazard Index (HI) were used to estimate and analyze the health risks to local residents (children, adults, and seniors). The Zn, Cr, Ni, Fe, Pb and Cu concentrations in food ranged from 16.02 to 61.48 mg kg^-1, 0.23-13.64 mg kg^-1, 0.10-5.90 mg kg^-1, 19.16-170.05 mg kg^-1, 0.15-3.62 mg kg^-1, and 0.53-2.74 mg kg^-1, respectively. Zn, Cr, Ni and Pb concentrations in all vegetables were above the national tolerance limits. Children had higher EDIs of heavy metals than that of adults and seniors. The THQ of single elements and the HI of combined elements indicated that the EDI of Pb and Cu showed the highest potential health risks, followed by the EDI of Zn and Fe, and Ni, Cr. High EDI of heavy metals resulted in much higher concentrations of heavy metals in hair and urine samples than those of normal Chinese residents, showing that residents around the smelter have potential health risks through daily food intake. The main sources of these heavy metals were from the consumption of rice and vegetables and it is imperative that measures should be taken to control this urgent problem.

Biomonitoring chronic lead exposure among battery manufacturing workers in Tunisia

The aim of the study was the biomonitoring of the chronic exposure to Pb by measuring its levels in blood, urine, and hair of battery workers. Blood lead (BPb), urinary lead (UPb), hair lead (HPb), and urinary δ-aminolevulinic acid (UALA) levels were determined for 52 workers in a battery plant and compared to those of 20 non-occupational exposed subjects (controls). BPb and UPb levels were determined by graphite furnace atomic absorption spectrometry (GFAAS). HPb levels were measured by triple quadrupole ICP-MS and UALA levels were determined using cation exchanger column. The measured levels were significantly higher compared to the controls exceeding the OSHA cutoff values (p < 0.01). The GM mean levels of BPb, UPb, UALA, and HPb of workers were 715 μg L^-1, 331 μg L^-1, 16.3 mg g^-1, and 234 μg g^-1, respectively. The GM mean levels of BPb, UPb, UALA, and HPb of controls were 93.6 μg L^-1, 36.3 μg L^-1, 1.9 mg g^-1, and 1.8 μg g^-1, respectively. Significant correlations were observed between BPb and UALA (r = 0.630, p = 0.000), UPb and UALA (r = 0.566, p = 0.000), and between BPb and HPb (r = 0.466, p = 0.004). The significant correlation between BPb and HPb suggests the usefulness of hair for assessing occupational exposure particularly when the study area presents medium to high levels of Pb pollution. The association between Pb biomarkers and potential confounding factors revealed significant influence of the occupational factor over smoking and alcohol consumption. The results of this study urge for the reinforcement of the implemented engineering controls and safety measures in order to reduce exposure and to address the health issues related to Pb poisoning.

Biomonitoring and health risks assessment of trace elements in various age- and gender-groups exposed to road dust in habitable urban-industrial areas of Hefei, China

The current study investigates the concentration of eleven trace elements in biomaterials including hair (85) and nails (85) along with seventy five (75) road dust samples collected from a healthy population of habitable urban-industrial areas of Hefei, China. The samples were acid digested and analyzed using ICP-MS for trace elements content. The mean concentration of Elements followed descending order of Zn > Mg > Fe > Cr > Al > Sn > Sr > Ti > Cu > As > Cd and Mg > Zn > Fe > Cr > Al > Sn > Ti > Cu > Sr > As > Cd in hair and nails, respectively. Overall, the concentration of elements was found to be high in female subject as compared to male. The concentration of trace elements in hair and nail exceeded the maximum permissible limits in most cases. The corresponding mean values from dust samples were fairly high as compared to background values of trace elements. Middle age groups (21-30 years and 31-40 years) were observed to be the most vulnerable there-by posing a high health risk, as the concentration of trace elements was significantly high in these groups except for Al, which was detected high in age < 20 in case of both male and female. A significantly high correlation was found between trace elements in biomaterials and those detected in dust samples. In hair samples, a significantly positive correlation was noticed for As with Mg, Zn, Sn and Fe, Sn/Mg and Mg/Ti. In the case of nails, a significant correlation was observed for elements like Al, Mg, Zn, Cr, and Cu. The Cluster and principal component analysis revealed industrial and vehicular emissions as main sources for trace elements exposure in humans.

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.

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

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

Investigation of Trace Elements in the Hair and Nail of Patients with Stomach Cancer

Trace metals are beneficial nutrient materials that act as essential cofactors in physiological processes. Recent evidence suggests that increase or decrease in certain trace metals may be related with risk and development of chronic diseases such as cancer. This study analyzed some trace elements level in hair and nail of patients with stomach cancer, and compared with their level in healthy controls. Trace elements (Cu, Fe, K, Li, Mg, Mn, Na, P, Se, Sr and Zn) are estimated in hair and nail of the 73 cancer patients and 83 controls by atomic absorption spectrophotometric method. The levels of Cu, K, Li, P and Se in hair and nail samples, were significantly higher in cases than controls. Levels of Mg and Sr were significantly lower in cases than controls. Fe level in hair samples was significantly higher in cases than controls. The mean concentrations of Fe, Se and P significantly increased with increasing cancer stage in the hair of patients. The average concentration of k also significantly increased with increasing cancer stage in the nail of patients. The results of our study show that there is an association between the increase in Cu, K, Li, P, Se and Fe, and stomach cancer development. Our results reveal that the increase in the trace elements could be a potential diagnostic marker to predict cancer progression and its etiology.