Occupational exposure to metals and other elements in the tractor production

Nickel and human sperm quality: a systematic review

BACKGROUND

Reproductive effects of chronic exposure to nickel (Ni), including sperm quality, have been a matter of debate given that published studies yielded contrasting results. We have, therefore, planned to systematically search and analyze medical literature with the aim to ascertain the association of exposure to nickel with the sperm quality in humans.

MATERIALS AND METHODS

We systematically searched Pubmed, Scopus and Embase for studies reporting the association of Ni with the sperm quality in humans with no time or language limits and used PRISMA to report the findings. The risk of bias was assessed using JBI critical appraisal checklist and SIGN tool. Because the reported effects were no coherent, meta-analysis was not possible.

RESULTS

All included studies were observational and planned to test the effect of a group of trace elements, but not Ni alone. We identified and included 19 studies from 23 publications, published from 12 countries, which assessed sperm quality, sperm DNA damage and sperm metabolome. Ni was quantified in blood, semen plasma, spermatozoa and urine. Sixteen included cross-sectional studies were of acceptable quality, whereas three more case-control reports were of poor quality. Multivariate models were reported in only eight studies. Overall, studies were inconsistent in the direction of effect, when elevated Ni was not associated with the outcome (N = 8 studies), or some association was present (N = 11 studies). In the latter, 9 studies yielded elevated risk and 2 studies exhibited protective effect. Only one report was in an occupationally exposed population with some association with tail defects, but present in both welders and controls.

CONCLUSIONS

Existing evidence from the studies in humans is inconsistent and does not confirm a clear adverse effect of higher Ni concentrations in blood, urine or semen on the sperm quality. Robust methodology must be a key issue in the future studies. Studies with more powerful evidence, such as cohort or experimental reports are needed.

Occupational exposure to fine particulate matter in the reinforced concrete production and its association with respiratory symptoms and lung function

BACKGROUND

Reinforced concrete production is widespread, but little is known about the occupational exposure to fine particulate matter (PM) in such workplaces, including from metalworking and concrete processing. Therefore, the aim was to characterize exposure to fine PM in the typical workplaces of the whole production cycle and to quantify the risk of respiratory symptoms and lung function in a cohort of reinforced concrete parts production industry.

METHODS

At a reinforced concrete parts producing facility in Almaty, we collected 50 personal PM2.5 samples from the main exposure sites and the measured mass concentrations using gravimetric method. Workers also completed questionnaires on a detailed working history, respiratory symptoms (chronic obstructive pulmonary disease (COPD) Assessment Tool (CAT)), followed by spirometry. The association of cumulative dose with CAT score and forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) was tested with multiple regression.

RESULTS

The highest PM2.5 concentrations were found in the concrete-mixing unit (median 1180 µg/m3), followed by metalworking (510 µg/m3), armature workshop (375 µg/m3) and molding site (245 µg/m3), different from the concentrations in the office (29.5 µg/m3), Kruskall-Wallis p < 0.001. Cumulative PM2.5 dose, mg/m3-year (beta 0.10 (95% confidence interval (CI) 0.05; 0.15)) was strongly associated with CAT score, whereas production with FEV1/FVC (beta -4.96 (-8.31; -1.61)), independent of smoking and chronic bronchitis and sex.

CONCLUSIONS

Mixing concrete and metalworks pose the greatest risk for worker's health in the reinforced concrete production from the inhalational exposure to aerosol, adversely affecting respiratory health.

Nickel-induced alterations to chromatin structure and function

Nickel (Ni), a heavy metal is prevalent in the atmosphere due to both natural and anthropogenic activities. Ni is a carcinogen implicated in the development of lung and nasal cancers in humans. Furthermore, Ni exposure is associated with a number of chronic lung diseases in humans including asthma, chronic bronchitis, emphysema, pulmonary fibrosis, pulmonary edema and chronic obstructive pulmonary disease (COPD). While Ni compounds are weak mutagens, a number of studies have demonstrated the potential of Ni to alter the epigenome, suggesting epigenomic dysregulation as an important underlying cause for its pathogenicity. In the eukaryotic nucleus, the DNA is organized in a three-dimensional (3D) space through assembly of higher order chromatin structures. Such an organization is critically important for transcription and other biological activities. Accumulating evidence suggests that by negatively affecting various cellular regulatory processes, Ni could potentially affect chromatin organization. In this review, we discuss the role of Ni in altering the chromatin architecture, which potentially plays a major role in Ni pathogenicity.

Biomarkers for occupational manganese exposure

Long-term inhalation exposure to manganese (Mn) metal or its inorganic compounds can result in manganism or subclinical neurofunctional deficits. Studies have described affected workers in Mn dioxide mining, Mn-containing ore crushing and milling facilities, manufacturing of dry-cell batteries, Mn steel and alloy production plants, and in welders. The objective of this study was to critically review existing evidence on the reliability of potential biomarkers of Mn exposure, specifically the relationship between inhalation exposure to Mn particulates in different occupational settings and Mn concentrations in blood and other biological fluids and tissues, with a particular focus on whole blood as a potentially useful medium for measuring internal tissue dose. We also examined available evidence on the relationship between Mn levels in blood and adverse clinical and subclinical neurotoxic outcomes. Three bibliographic databases were searched for relevant studies and identified references were screened by two independent reviewers. Of the 6338 unique references identified, 76 articles were retained for data abstraction. Findings indicate that the relationships between Mn in blood and both external Mn exposure indices and neurofunctional impairments are limited and inconsistent. Different sources of exposure to Mn compounds, heterogeneity in the methodological approaches, and inadequate reporting of essential information limited direct comparison of the reported findings. Among the Mn-exposure biomarkers considered in this review - including biomarkers in blood, plasma, serum, erythrocytes, urine, bone, toenails, fingernails, hair, saliva - biomarkers in whole blood may provide to be most useful in Mn biomonitoring and risk assessment.

Occupational disease claims and non-occupational morbidity in a prospective cohort observation of nickel electrolysis workers

Exposure to nickel aerosol in the nickel production is associated with greater occupational risk, yet little is known how many workers will develop an occupational disease and claim compensation. The aim of this analysis was to prospectively observe a cohort of nickel electrolysis workers and quantitatively assess confirmed occupational disease claims. We observed a cohort of nickel electrolysis workers (N = 1397, median age 39, 68% males) from 2008 till 2020 in one of the largest nickel producers in the Russian High North. Cumulative incidence of confirmed occupational disease claims in seven occupational groups, including electrolysis operators, hydrometallurgists, crane operators, final product cleaners, metalworkers, electricians and 'other' was analyzed and supplemented with Cox proportional hazards regression, yielding hazard ratios (HR) with their 95% confidence intervals (CI) of occupational disease claims for each group. N patients with occupational disease claims varied from 1 in 2016 to 22 in 2009, and in total 87 patients developed one or more occupational diseases (cumulative incidence 6.2%, p < 0.001 between seven groups). Accounting for 35,527 person-years of observation in total, cleaners exhibited the greatest risk (HR 2.58 (95% CI 1.43-4.64)), also adjusted for smoking, number of non-occupational diseases and group 2 (hydrometallurgists). Smoking was independently associated with having an occupational disease claim in all groups (p < 0.001), as was the number of non-work-related diseases in six groups of seven. Despite consistent improvement in the exposure control measures in nickel production, occupational morbidity persists. More effort is needed to reduce exposure in final product cleaners.

Transcriptional repression of E-cadherin in nickel-exposed lung epithelial cells mediated by loss of Sp1 binding at the promoter

E-cadherin plays a central role in the stability of epithelial tissues by facilitating cell-cell adhesion. Loss of E-cadherin expression is a hallmark of epithelial-mesenchymal transition (EMT), a major event in the pathogenesis of several lung diseases. Our earlier studies showed that nickel, a ubiquitous environmental toxicant, induced EMT by persistently downregulating E-cadherin expression in human lung epithelial cells and that the EMT remained irreversible postexposure. However, the molecular basis of persistent E-cadherin downregulation by nickel exposure is not understood. Here, our studies show that the binding of transcription factor Sp1 to the promoter of E-cadherin encoding gene, CDH1, is essential for its expression. Nickel exposure caused a loss of Sp1 binding at the CDH1 promoter, resulting in its downregulation and EMT induction. Loss of Sp1 binding at the CDH1 promoter was associated with an increase in the binding of ZEB1 adjacent to the Sp1 binding site. ZEB1, an EMT master regulator persistently upregulated by nickel exposure, is a negative regulator of CDH1. CRISPR-Cas9-mediated knockout of ZEB1 restored Sp1 binding at the CDH1 promoter. Furthermore, ZEB1 knockout rescued E-cadherin expression and re-established the epithelial phenotype. Since EMT is associated with a number of nickel-exposure-associated chronic inflammatory lung diseases including asthma, fibrosis and cancer and metastasis, our findings provide new insights into the mechanisms associated with nickel pathogenesis.

Epithelial-mesenchymal transition: Insights into nickel-induced lung diseases

Nickel compounds are environmental toxicants, prevalent in the atmosphere due to their widespread use in several industrial processes, extensive consumption of nickel containing products, as well as burning of fossil fuels. Exposure to nickel is associated with a multitude of chronic inflammatory lung diseases including asthma, chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis. In addition, nickel exposure is implicated in the development of nasal and lung cancers. Interestingly, a common pathogenic mechanism underlying the development of diseases associated with nickel exposure is epithelial-mesenchymal transition (EMT). EMT is a process by which the epithelial cells lose their junctions and polarity and acquire mesenchymal traits, including increased ability to migrate and invade. EMT is a normal and essential physiological process involved in differentiation, development and wound healing. However, EMT also contributes to a number of pathological conditions, including fibrosis, cancer and metastasis. Growing evidence suggest that EMT induction could be an important outcome of nickel exposure. In this review, we discuss the role of EMT in nickel-induced lung diseases and the mechanisms associated with EMT induction by nickel exposure.

Hair mineral analysis in the population of students living in the Lower Silesia region (Poland) in 2019: Comparison with biomonitoring study in 2009 and literature data

The paper presents a comparative analysis of biomonitoring research results using hair mineral analysis today and 10 years ago. The aim of the present work was to examine the impact of individual factors, on the content of elements in human hair. The mineral analysis of 115 hair samples was carried out using ICP-OES and AAS technique. It was shown that calcium, barium, copper, mercury, magnesium, manganese and selenium content depend on gender and is higher for women. Statistically significant synergistic correlations were identified between the following pairs of elements: (Ca-Mg), (P-S), (Mo-Sb) and (Ba-Pb). The results of the present work were compared with the previous assessment in 2009 on students of the same age. The content of most of the heavy metals in hair was reduced significantly, which is a sign of the improving state of the local environment. The greatest decrease was recorded for silver (96.6%), arsenic (93.4%), mercury (45.1%), lead (67.7%), antimony (55.2%), thallium (10 times) and cobalt (93.7%). The level of the following elements increased: Ba: 27.3%, Cu: 28.5%, Ni: 22.4%, Ti: 191%, Zn: 11.0%. Changes in the content of most heavy metals in hair have been noted, as well as changes of reference ranges, which may indicate an improvement in the state of the environment in Wrocław, Lower Silesia (Poland) over the last 10 years. These results were confirmed by biomonitoring studies carried out with human hair, which was shown to be a reliable biomarker of human exposure to toxic elements.

Bifunctional single-labelled oligonucleotide probe for detection of trace Ag(I) and Pb(II) based on cytosine-Ag(I)-cytosine mismatches and G-quadruplex

A novel bifunctional oligonucleotide (OND) probe with single fluorescent group HEX labelled at 5'-end was designed for detecting trace Ag(I) and Pb(II) in real samples. In the presence of Ag(I), the hairpin structure originating from Ag(I) induced cytosine-Ag(I)-cytosine mismatches causes the proximity of the HEX to the consecutive guanine bases (G)₄ at 3'-terminal, resulting in the fluorescence quenching of the HEX. While in the presence of Pb(II), the G-quadruplex structure originating from two G-quartet planes by the intramolecular hydrogen bond with Pb(II) also causes the HEX approaching the (G)₄ terminal and consequently the fluorescence quenching. The results showed the quantitative detection of trace Ag(I) and Pb(II) both in the linear response ranges of 1.0-20.0 × 10^-9 mol L^-1 with no visible interferences of other 11 metal ions observed. And the detection limits were 82 × 10^-12 mol L^-1 for Ag(I), 92 × 10^-12 mol L^-1 for Pb(II), respectively. The fluorescence quenching mechanism of the (G)₄ to HEX was verified to be the photoinduced electron transfer in the aspect of thermodynamics. This method provided a feasible application for sensitive and selective detection of Pb(II) and Ag(I) in water and Chinese traditional herbs with convenient operation.

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

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

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.