Study of occupational exposure to brick kiln emissions on heavy metal burden, biochemical profile, cortisol level and reproductive health risks among female workers at Rawat, Pakistan

Toxicological profile and potential health concerns through metals and trace elements exposure in brick kiln workers from Lahore, Pakistan

This study examined levels of lead (Pb), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), and arsenic (As) in blood, hair, and nails of 18 brick kiln workers from three brick kiln units located around a metropolitan city, Lahore, Pakistan. All the trace elements except Hg and As were detected in the studied matrices of Brick kiln workers. In general, brick kiln workers reflect the highest concentration of Pb, followed by Cd, Cr, and Cu. Of the pollutants analyzed, Pb has the highest mean (min-max) concentrations at 0.35 (0.09-0.65) in blood (μg/mL), 0.34 (0.14-0.71) in hairs (μg/g), and 0.44 (0.32-0.59) in nails (μg/g) of brick kiln workers. Following Pb, the trend was Cd 0.17 (0.10-0.24), Cu 0.11(0.03-0.27), and Cr 0.07 (0.04-0.08) in blood (μg/mL), followed by Cr 0.11(0.05-0.20), Cd 0.09 (0.03-0.13), and Cu 0.08 (0.04-0.16) in hairs (μg/g) and Cu 0.16 (0.05-0.36), Cd 0.13 (0.11-0.17), and Cr 0.10 (0.05-0.14) in nails (μg/g) respectively. Relatively higher concentrations of metals and other trace elements in blood depicts recent dietary exposure. The difference of trace elements except Pb was non-significant (P > 0.05) among studied matrices of workers as well as between Zigzag and traditional exhaust-based brick kilns. The concentrations of Pb, Cd and Cr in blood of brick kilns workers are higher than the values reported to cause health problems in human populations. It is concluded that chronic exposure to metals and other trace elements may pose some serious health risks to brick kiln workers which needs to be addressed immediately to avoid future worst-case scenarios.

Joint and interactive effects of metal mixtures on liver damage: Epidemiological evidence from repeated-measures study

BACKGROUND

The impact of heavy metals on liver function has been examined in numerous epidemiological studies. However, these findings lack consistency and longitudinal validation.

METHODS

In this study, we conducted three follow-up surveys with 426 participants from Northeast China. Blood and urine samples were collected, along with questionnaire information. Urine samples were analyzed for concentrations of four metals (chromium [Cr], cadmium [Cd], lead [Pb], and manganese [Mn]), while blood samples were used to measure five liver function indicators (alanine aminotransferase [ALT], aspartate aminotransferase [AST], albumin [ALB], globulin [GLB], and total protein [TP]). We utilized a linear mixed-effects model (LME) to explore the association between individual heavy metal exposure and liver function. Joint effects of metal mixtures were investigated using quantile g-computation and Bayesian kernel machine regression (BKMR). Furthermore, we employed BKMR and Marginal Effect models to examine the interaction effects between metals on liver function.

RESULTS

The LME results demonstrated a significant association between urinary heavy metals (Cr, Cd, Pb, and Mn) and liver function markers. BKMR results indicated positive associations between heavy metal mixtures and ALT, AST, and GLB, and negative associations with ALB and TP, which were consistent with the g-comp results. Synergistic effects were observed between Cd-Cr on ALT, Mn-Cr and Cr-Pb on ALB, while an antagonistic effect was found between Mn-Pb and Mn-Cd on ALB. Additionally, synergistic effects were observed between Mn-Cr on GLB and Cd-Cr on TP. Furthermore, a three-way antagonistic effect of Mn-Pb-Cr on ALB was identified.

CONCLUSION

Exposure to heavy metals (Cr, Cd, Mn, Pb) is associated with liver function markers, potentially leading to liver damage. Moreover, there are joint and interaction effects among these metals, which warrant further investigation at both the population and mechanistic levels.

Evaluation of renal function in precarious workers exposed to heavy metals in vulnerable scenarios in the metropolitan area of San Luis Potosí, México

The aim of the study was to evaluate renal function in three groups of precarious workers: garbage recyclers (REC), quarry workers (CAN), and brick makers (LAD). Samples of urine and blood were collected to evaluate clinical parameters and the metal levels in urine was measured using ICP-MS. REC group had the highest concentrations of chromium in urine (36.03 ± 27.2 µg/l) compared to CAN and LAD groups. Mercury concentrations were higher in the LAD group (3.7 ± 0.8 µg/l). Additionally, arsenic was detected in both CAN and REC groups (25.4 ± 26.2 and 19.09 ± 16.7 µg/l, respectively), while arsenic concentrations in LAD were higher (47.2 ± 30.8 µg/l). In kidney biomarkers, β2-microglobulin concentrations were higher in the REC group (87867 ± 115159.5 ng/g UCr). Similarly, cystatin-C concentrations were higher in the REC group (32795.61 ± 34965.8 ng/g UCr). The data suggests that precarious workers are exposed to heavy metals and have elevated protein levels that contribute to kidney damage.

Influence of chlorine on co-processing of hazardous wastes in brick kilns

Brick kiln co-treatment is a novel industrial hazardous wastes (IHWs) utilization process. However, the effects of chlorine (Cl) in wastes on heavy metals (HMs) during this process are overlooked. This study investigated the stabilization/solidification (S/S) and volatilization, as well as long and short-term leaching, of HMs in Cl-containing bricks. The results indicated enhanced formations of stable mineral phases (NiFe2O4, Ni2SiO4, Cd3Al2Si3O12, CdSiO3, FeCr2O4, Cr2O3, CuFe2O4, and CuAl2O4) in bricks at a low sintering temperature (800 °C) due to the affinity between Cl and HMs. By comparing HM concentrations before and after sintering in bricks, the study observed that Cl's presence significantly elevated the volatilization rates for Cd and Cu by 30.8% and 14.2%, respectively. In contrast, the effect on volatilization for Ni and Cr was not significant. Additionally, utilizing the NEN 7375 method, the cumulative leaching rates of Ni, Cd, Cr, and Cu over a 64-day experiment under extremely acidic conditions were 0.22%, 7.18%, 0.01%, and 1.46%, respectively. Similarly, higher short-term leaching rates of Cd (4.03%) and Cu (5.73%) than those of Ni (0.94%) and Cr (0.08%) were observed. This finding might be attributed to the lower stability of the Cd and Cu solid phases under acidic environments compared to those of Ni and Cr. Surface wash-off, dissolution, and diffusion were the processes governing HM leaching from bricks. The 10-year projections revealed a minimal release of HMs during future extended leaching, implying the successful S/S of HMs. This study provides a reference for assessing the environmental impacts of brick kiln co-processing of Cl-containing IHWs.

Relationship of individual and mixed urinary metals exposure with liver function in the China National Human Biomonitoring (CNHBM) of Zhejiang Province

BACKGROUND

Heavy metals have been reported to affect liver function. However, there is currently little and inconsistent knowledge about the effects of combined and individual urinary metals on specific parameters of liver function in the general population. Therefore, this study aimed to investigate their associations.

METHODS

This study involved 807 general population from the China National Human Biomonitoring of Zhejiang Province 2017-2018. Concentrations of urinary metals, including Chromium (Cr), Cobalt (Co), Nickle (Ni), Arsenic (As), Selenium (Se), Molybdenum (Mo), Cadmium (Cd), Thallium (Tl) and Lead (Pb) were measured. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), total protein (TP), albumin (ALB), direct bilirubin (DBIL), total bilirubin (TBIL) as liver function biomarkers. Multivariable linear regression and weighted quantile sum (WQS) regression were employed to explore the associations of urinary metals with liver function biomarkers. Subgroup analysis stratified by gender and age, excluding smokers and drinkers for sensitivity analysis.

RESULTS

Both statistical models indicated that urinary metals were positively associated with ALT and AST, while negatively with TP, ALB, DBIL and TBIL. In the WQS analysis, each quartile increase in the ln-transformed levels of metal mixtures was associated with 4.11 IU/L (95% CI: 1.07, 7.15) higher ALT and 3.00 IU/L (95% CI: 1.75, 4.25) higher AST, as well as, with 0.67 g/L (95% CI: 1.24, -0.11) lower TP, 0.74 g/L (95% CI: 1.09, -0.39) lower ALB, 0.38 μmol/L (95% CI: 0.67, -0.09) lower DBIL, and 1.56 μmol/L (95% CI: 2.22, -0.90) lower TBIL. The association between urinary metals and ALT was primarily driven by Cd (55.8%), Cr contributed the most to the association with AST (20.2%) and TBIL (45.2%), while the association with TP was primarily driven by Ni (38.2%), the association with ALB was primarily driven by As (32.8%), and the association with DBIL was primarily driven by Pb (30.9%). The associations between urinary metals and liver function might differ by sex and age.

CONCLUSION

Urinary metals were significantly associated with liver function parameters. Further studies are required to clarify the relationship between heavy metals and liver function.

Toxicological profile and health risk assessment through trace elements exposure in brick kiln workers from Lahore, Pakistan.. [DOI: 10.21203/rs.3.rs-3267981/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

This study examined lead (Pb), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), and arsenic (As) levels in blood, hair, and nails of 18 brick kiln workers from three brick kiln units located around a metropolitan city, Lahore, Pakistan. All the trace elements except Hg and As were detected in the studied matrices of Brick kiln workers. In general, brick kiln workers had the highest concentration of Pb, followed by Cd, Cr, and Cu. Among trace elements, Pb has the highest mean (min-max; µg/g)) concentrations at 0.35 (0.09–0.65) in blood, 0.34 (0.14–0.71) in hairs, and 0.44 (0.32–0.59) in nails of brick kiln workers. Following Pb, the trend was Cd 0.17 (0.10–0.24), Cu 0.11(0.03–0.27), and Cr 0.07 (0.04–0.08) in blood, followed by Cr 0.11(0.05–0.20), Cd 0.09 (0.03–0.13), and Cu 0.08 (0.04–0.16) in hairs and Cu 0.16 (0.05–0.36), Cd 0.13 (0.11–0.17), and Cr 0.10 (0.05–0.14) in nails respectively. The difference of trace metals except Pb was non-significant (P > 0.05) among studied matrices of workers as well as between Zigzag and traditional exhaust based brick kilns. Non-carcinogenic risk of Pb and Cd were above USEPA and WHO limits while Pb, Cd, and Cr carcinogenic risks were close to the threshold limits. It is concluded that chronic exposure to trace elements poses serious health risks to brick kiln workers which needs to be addressed to avoid future worst-case scenarios.

Mediation Effect of Body Mass Index on the Association of Urinary Nickel Exposure with Serum Lipid Profiles

The objective of this study was to determine the relationship of urinary nickel (U-Ni) exposure to serum lipid profiles and the mediation effect of body mass index (BMI) in a US general population. We analyzed the cross-sectional data from 3517 participants in the National Health and Nutrition Examination Survey (NHANES) (2017-March 2020). Multivariable linear regression and restricted cubic spline (RCS) regression were conducted to explore the association of U-Ni with four serum lipids and four lipids-derived indicators. Mediation analysis was performed to examine the effect of BMI on the relationship between U-Ni levels and serum lipid profiles. Compared with the lowest quartile, the β with 95% confidence intervals (CIs) in the highest quartile were - 12.83 (- 19.42, - 6.25) for total cholesterol (TC) (P for trend < 0.001), - 12.76 (- 19.78, - 5.74) for non-high-density lipoprotein cholesterol (non-HDL-C) (P for trend = 0.001) and - 0.29 (- 0.51, - 0.07) for TC/HDL-C (P for trend = 0.007) in the fully adjusted model. RCS plots showed the linear association of log₂-transformed U-Ni levels with TC, non-HDL-C and TC/HDL-C (P for nonlinearity = 0.294, 0.152, and 0.087, respectively). Besides, BMI decreased monotonically in correlation with increasing U-Ni levels (P for trend < 0.001). Mediation analysis revealed that BMI significantly mediated the relationship of U-Ni to TC, non-HDL-C and TC/HDL-C with mediated proportions of 11.17%, 22.20% and 36.44%, respectively. In summary, our findings suggest that BMI mediates the negative association of U-Ni with TC, non-HDL-C, and TC/HDL-C in the US general population.

The impact of brick kilns on environment and society: a bibliometric and thematic review

Bricks have a long history of being utilized as a construction material across the globe. The production processes involved in the manufacture of bricks have a significant impact on the environment, human health, economy, and society. This study conducts a thematic and bibliometric analysis to provide an in-depth review of the effects of brick kilns on humans and the environment. The PRISMA framework was used to identify relevant articles from the Web of Science database, resulting in the selection and critical review of 348 articles. The bibliometric analysis included an evaluation of historical growth, keywords, citation and co-citation, organizations, and countries. The articles were published in 213 journals, written by 1396 authors from 670 institutions in 66 countries. Thematic analysis revealed that brick kilns have a negative impact on the environment, including soil damage, and cause health problems for kiln workers and animals. Modern slavery and societal issues also persist in developing countries. The current research is focused on finding alternative materials for brick manufacturing, improving industry energy efficiency, managing waste, and technological advancements, such as the implementation of the zigzag or Hoffmann kiln to reduce pollution. In developing countries, utilizing waste from other industries in brick production can effectively lower production costs. While developed countries have embraced advanced technologies for brick production, it is recommended that developing countries adopt awareness campaigns to encourage the upgrading of kilns to cleaner and more sustainable systems. Future research directions should aim to support brick kiln owners in adopting such systems.

Associations of metals and metals mixture with lipid profiles: A repeated-measures study of older adults in Beijing

Metals inevitably and easily enter into human bodies and can induce a series of pathophysiological changes, such as oxidative stress damage and lipid peroxidation, which then may further induce dyslipidemia. However, the effects of metals and metals mixture on the lipid profiles are still unclear, especially in older adults. A three-visits repeated measurement of 201 older adults in Beijing was conducted from November 2016 to January 2018. Linear Mixed Effects models and Bayesian kernel machine regression models were used to estimate associations of eight blood metals and metals mixture with lipid profiles, including total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), Castelli risk indexes I (CRI-1), Castelli risk indexes II (CRI-2), atherogenic coefficient (AC), and non-HDL cholesterol (NHC). Cesium (Cs) was positively associated with TG (β_Cs = 0.14; 95% CI: 0.02, 0.26) whereas copper (Cu) was inversely related to TG (β_Cu = -0.65; 95%CI: -1.14, -0.17) in adjusted models. Manganese (Mn) was mainly related to higher HDL-C (β_Mn = 0.14; 95% CI: 0.07, 0.21) whereas molybdenum showed opposite association. Metals mixture was marginally positive associated with HDL-C, among which Mn played a crucial role. Our findings suggest that the effects of single metal on lipid profiles may be counteracted in mixtures in the context of multiple metal exposures; however, future studies with large sample size are still needed to focus on the detrimental effects of single metals on lipid profiles as well as to identify key components.

A Molecular Mechanism to Explain the Nickel-Induced Changes in Protamine-like Proteins and Their DNA Binding Affecting Sperm Chromatin in Mytilus galloprovincialis: An In Vitro Study

Nickel is associated with reproductive toxicity, but little is known about the molecular mechanisms of nickel-induced effects on sperm chromatin and protamine-like proteins (PLs). In the present work, we analyzed PLs from Mytilus galloprovincialis by urea-acetic acid polyacrylamide gel electrophoresis (AU-PAGE) and SDS-PAGE and assessed their binding to DNA by Electrophoretic Mobility Shift Assay (EMSA) after exposing mussels to 5, 15, and 35 µM NiCl2 for 24 h. In addition, a time course of digestion with MNase and release of PLs from sperm nuclei by the NaCl gradient was performed. For all exposure doses, in AU-PAGE, there was an additional migrating band between PL-III and PL-IV, corresponding to a fraction of PLs in the form of peptides detected by SDS-PAGE. Alterations in DNA binding of PLs were observed by EMSA after exposure to 5 and 15 µM NiCl2, while, at all NiCl2 doses, increased accessibility of MNase to sperm chromatin was found. The latter was particularly relevant at 15 µM NiCl2, a dose at which increased release of PLII and PLIII from sperm nuclei and the highest value of nickel accumulated in the gonads were also found. Finally, at all exposure doses, there was also an increase in PARP expression, but especially at 5 µM NiCl2. A possible molecular mechanism for the toxic reproductive effects of nickel in Mytilus galloprovincialis is discussed.

Effects of cadmium and lead co-exposure on glucocorticoid levels in rural residents of northwest China

Cadmium (Cd) and lead (Pb) are important environmental endocrine disruptors that are associated with adverse health problems. However, the effects of co-exposure to Cd and Pb on glucocorticoids (GCs) in the body at environmental levels are limited. A total of 468 subjects from the Dongdagou-Xinglong cohort (DDG-XL) were included in this study. We measured the serum levels of two representative endogenous GCs [cortisol (CRL) and cortisone (CRN)], and whole blood levels of Cd and Pb. Multiple linear regression models were constructed to explore the associations of single or combined Cd and Pb exposure with serum CRL and CRN levels. The interactive effects of Cd and Pb on GCs were further assessed using mediation analysis and moderation analysis. Single-heavy metal exposure analysis with adjustment for potential confounders showed that the serum CRL level decreased when the blood Cd or Pb concentration gradually increased (P trend <0.01). Additionally, subjects with high Cd or Pb exposure (Q4) had significantly reduced serum CRN levels compared to those with low Cd or Pb exposure (Q1) (P < 0.05). In Cd and Pb co-exposure analysis, significant negative dose-response relationships were observed between co-exposure to Cd and Pb and serum CRL and CRN levels. Furthermore, mediation analysis showed that Cd completely mediated the relationship between Pb and GCs, and moderation analysis suggested that Pb might weaken the negative relationship between Cd and GCs. These findings suggest that single or combined exposure to Cd and Pb interferes with the homeostasis of serum CRL and CRN levels. Furthermore, we innovatively propose that Cd and Pb may have interactive effects on GCs levels, and Pb can antagonize the negative relationship between Cd and GCs, which may provide clues for further studies on endocrine and metabolic disorders related to these heavy metals.

Independent, combine and interactive effects of heavy metal exposure on dyslipidemia biomarkers: A cross-sectional study in northeastern China

Dyslipidemia is a common disease in the older population and represents a considerable disease burden worldwide. Epidemiological and experimental studies have indicated associations between heavy metal exposure and dyslipidemia; few studies have investigated the effects of heavy metal mixture and interactions between metals on dyslipidemia. We recruited 1121 participants living in heavy metal-contaminated and control areas in northeast China from a cross-sectional survey (2017-2019). Urinary metals including chromium (Cr), cadmium (Cd), lead (Pb), and manganese (Mn) and dyslipidemia biomarkers, namely triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) levels, were measured. The generalized linear model (GLM) was used to explore the association of a single metal with dyslipidemia biomarkers. Bayesian kernel machine regression (BKMR) and multivariable linear regression were performed to explore the overall effect of metal mixture and the interaction between metals on dyslipidemia. Heavy metal mixture was positively associated with LDL-C, TC, and TG and negatively with HDL-C. In multivariable linear regression, Pb and Cd exhibited a synergistic association with LDL-C in the participants without hyperlipemia. Mn-Cd and Pb-Cr also showed a synergistic association with increasing the level of LDL-C in subjects without hyperlipemia. Cd-Cr showed an antagonistic association with HDL-C, respectively. Cr-Mn exhibited an antagonistic association with decreased HDL-C and TG levels. No significant interaction was noted among the three metals. Our study indicated that exposure to heavy metals is associated with dyslipidemia biomarkers and the presence of potential synergistic or antagonistic interactions between the heavy metals.

Assessment and mapping of total suspended particulate and soil quality around brick kilns and occupational health issues among brick kilns workers in Pakistan

Brick kilns constitute one of the major sources of environmental degradation in Pakistan. The present study was conducted to determine the soil quality and total suspended particulates (TSPs) around the brick kilns and assess the health effects on brick kiln workers. Four brick kilns were selected, two each at Sheikhupura and Pattoki city. The soil quality was assessed by analyzing pH, electrical conductivity, moisture content, nitrogen, phosphorus, potassium content, and heavy metal concentration while TSPs were measured by hand-held Microdust Pro Real time monitor. Average TSP concentration around brick kilns at Sheikhupura and Pattoki ranged between 1100 and 1200 µg/m³ and between 550 and 600 µg/m³ respectively which exceeded the Punjab Ambient Air Standards. The soil was slightly acidic (Sheikhupura: average pH = 6.41; Pattoki: average pH = 6.6) while all other analyzed parameters, except heavy metals, were lower than the required FAO Standards for good quality agriculture soil. Heavy metal accumulation in soil samples followed the general order zinc (Zn) > chromium (Cr) > nickel (Ni) > manganese (Mn) > cadmium (Cd) > copper (Cu). For assessment of occupational health and safety issues, all 440 brick kiln workers from the study areas were interviewed. Mostly, brick kiln workers suffered from chronic back pain (84%), skin issues (80.5%), dry cough (72.9%), common cold (46.1%), and shortness of breath (17.1%). The vulnerability risk varied with the nature of the work as workers engaged in brick baking were more vulnerable to respiratory issues than were those in molding task. The study concludes that brick kilns are a source of increased TSP, deteriorated surrounding soil quality, and impaired worker health. It is necessary to regulate these activities and implement requisite health and safety measures.

Human supplementation with Pediococcus acidilactici GR-1 decreases heavy metals levels through modifying the gut microbiota and metabolome

Exposure to heavy metals (HMs) is a threat to human health. Although probiotics can detoxify HMs in animals, their effectiveness and mechanism of action in humans have not been studied well. Therefore, we conducted this randomized, double-blind, controlled trial on 152 occupational workers from the metal industry, an at-risk human population, to explore the effectiveness of probiotic yogurt in reducing HM levels. Participants were randomly assigned to two groups: one consumed probiotic yogurt containing the HM-resistant strain Pediococcus acidilactici GR-1 and the other consumed conventional yogurt for 12 weeks. Analysis of metal contents in the blood revealed that the consumption of probiotic yogurt resulted in a higher and faster decrease in copper (34.45%) and nickel (38.34%) levels in the blood than the consumption of conventional yogurt (16.41% and 27.57%, respectively). Metagenomic and metabolomic studies identified a close correlation between gut microbiota (GM) and host metabolism. Significantly enriched members of Blautia and Bifidobacterium correlated positively with the antioxidant capacities of GM and host. Further murine experiments confirmed the essential role of GM and protective effect of GR-1 on the antioxidative role of the intestine against copper. Thus, the use of probiotic yogurt may be an effective and affordable approach for combating toxic metal exposure through the protection of indigenous GM in humans.

ClinicalTrials.gov identifier: ChiCTR2100053222

Contamination of breast milk with lead, mercury, arsenic, and cadmium in Iran: a systematic review and meta-analysis

Breast milk is a complete food for the development of the newborn, but it can also be an important route for environmental pollutants transmission to the infants. This study was aimed to evaluate the status of heavy metals including lead (Pb), mercury (Hg), cadmium (Cd) and arsenic (As) in the breast milk of Iranian mothers. The international databases including Scopus, PubMed, Web of Science and the Persian electronic databases including Scientific Information Database, IranMedex and Magiran were examined to find relevant articles published until July 2021. A total of 23 studies examined the levels of toxic metals in Iranian breast milk samples. According to the findings, the pooled average concentrations (µg/L) of Pb, Cd, Hg and As were 25.61, 2.40, 1.29 and 1.16, respectively. The concentration of Hg and Pb in colostrum milk was more than twice of mature milk. The Hg mean concentration in the breast milk of mothers with at least one amalgam-filled tooth was approximately three times that of mothers without amalgam-filled teeth. Risk assessment analysis indicated that the intake of Pb and Hg by infants through breastfeeding can be considered a health concern in Iran. It seems necessary to reduce the Pb exposure of pregnant and lactating women in Iran. However, more extensive studies are needed to clarify the toxic metals' exposure status of infants through breast milk in other parts of the country.

Biochemical and reproductive biomarker analysis to study the consequences of heavy metal burden on health profile of male brick kiln workers

The present study aims to assess the effect of a heavy metal burden on general health, biochemical parameters, an antioxidant enzyme, and reproductive hormone parameters in adult male brick kiln workers from Pakistan. The study participants (n = 546) provided demographic data including general health as well as body mass index. Blood was collected to quantitatively assess hematological, biochemical, and reproductive hormone parameters as well as heavy metal concentrations using both atomic absorption spectroscopy (AAS) and particle-induced X-ray emission (PIXE). The data showed that 10% of the brick kiln workers were underweight and 10% obese (P = 0.059), with workers also reporting multiple health issues. Heavy metal concentrations utilizing AAS revealed significantly (p = 0.000) higher levels of cadmium, chromium, and nickel, while PIXE detected more than permissible levels of Si, P, S, Cl, K, Ca, Zn, Ti (p = 0.052), Mn (p = 0.017), Fe (p = 0.055), Co (p = 0.011), Ni (p = 0.045), and Cu (p = 0.003), in the blood of kiln workers. Moreover, a significant increase in platelet count (P = 0.010), a decrease in sodium dismutase levels (p = 0.006), a major increase in reactive oxygen species (p = 0.001), and a reduction in protein content (p = 0.013) were evident. A significant increase in cortisol levels (p = 0.000) among the workers group was also observed. The concentration of LH and FSH increased significantly (p = 0.000), while that of testosterone decreased (p = 0.000) in the worker group compared with controls. A significant inverse relationship was found between cortisol, LH (r =  - 0.380), and FSH (r =  - 0.946), while a positive correlation between cortisol and testosterone was also evident (r = 0.164). The study concludes that increased heavy metal burden in the blood of brick kiln workers exposes them to the development of general and reproductive health problems due to compromised antioxidant enzyme levels, increased oxidative stress conditions, and a disturbing reproductive axis.

Association between urine metals and liver function biomarkers in Northeast China: A cross-sectional study

BACKGROUND

After heavy metals enter the body, they affect a variety of organs, particularly the main metabolic organ, the liver. Moreover, people are more likely to be exposed to multiple metals than to a single metal. We explored the associations between exposure to a heavy metal mixture and liver function biomarkers.

METHODS

This study involved 1171 residents living in areas with or without heavy metal exposure in northeast China. Urine concentrations of chromium (Cr), cadmium (Cd), lead (Pb), and manganese (Mn) were measured. Total protein (TP), albumin (ALB), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were used as biomarkers of liver function. A generalized linear model (GLM), quantile g-computation, and Bayesian kernel machine regression (BKMR) were used to explore the associations between the four metals and liver function.

RESULTS

GLM analysis revealed that Cr level was negatively associated with TP (β = - 0.57; 95% CI: - 0.89, - 0.26) and ALB (β = - 0.27; 95% CI: - 0.47, - 0.07) levels, and Cd level was positively associated with AST (β = 1.04; 95% CI: 0.43, 1.65) and ALT (β = 0.94; 95% CI: 0.08, 1.79) levels. ALB (β = 0.26; 95% CI: 0.10, 0.41) and ALT (β = 0.52; 95% CI: 0.02, 1.02) levels were positively associated with urine Mn concentration. The quantile g-computation indicated that exposure to a mixture of the four metals was significantly associated with TP (β = - 0.56; 95% CI: - 0.94, - 0.18) and ALT (β = 0.84; 95% CI: 0.04, 1.63) levels. Among the metals, Cr had the strongest effect on TP and Cd had that on AST. The BKMR model indicated that mixed metal exposure was negatively associated with TP and ALB levels and positively associated with ALT and AST levels.

CONCLUSION

Exposure to mixtures of heavy metals may influence liver function. Cr and Cd may be the largest contributors.

Zig-zag technology adoption behavior among brick kiln owners in Pakistan

This study uses the theory of planned behavior to examine the individual's intentions and zig-zag kiln technology adoption attitude in responding to carbon emissions in Pakistan. This study is based on cross-sectional data and a representative sample of 335 brick kilns owners from 11 districts of Punjab province of Pakistan is collected. Partial least squares structural equation modeling technique was used for the analysis. Results depicted that environmental concern and self-efficacy have a significant influence on attitude toward sustainable technology while subjective norms have a significant effect on intentions toward zig-zag kiln technology. A 1% increase in environmental concern and self-efficacy increases sustainable environmental technology by 24% and 58%, respectively. Furthermore, perceived behavioral control and intentions also significantly impact adoption attitude, and a 1% increase in perceived behavioral control and intentions increase the zig-zag kiln adoption attitude by 68% and 30%, respectively. Results depicted that adoption attitude is significantly determined by these explanatory variables. The study's findings provided new evidence for the government to place more emphasis on enhancing kiln owners' attitudes, social norms, and perceived behavioral control, which would lead towards the adoption of this new technique.

Does gender equality in education matter for environmental sustainability in sub-Saharan Africa?

The present study provides a macro-level framework for gender issues and their link to energy policies and environmental quality, in line with the sustainable development goals (SDG). It examines the relationship between environmental sustainability, gender equality in education, energy consumption, and sub-Saharan Africa's income by using cointegration analysis and autoregressive distributed lag (ARDL) method. The study's estimation results are consistent with the Environmental Kuznets Curve (EKC) hypothesis and policy actions suggested by eco-feminist theories in both the short-run and long-run and show that gender equality in education has positively related to environmental sustainability in sub-Saharan Africa.

Mechanisms underlying reproductive toxicity induced by nickel nanoparticles identified by comprehensive gene expression analysis in GC-1 spg cells

The public around the world is increasingly concerned about male reproductive health. The impact of nickel nanoparticles (Ni NPs) on male reproductive toxicity including sperm production, motility and fertilizing capacity has been confirmed by our previous researches. In the current study of Ni NPs-inducing toxicity, the expression profiles of piRNAs and their predicted target genes associated with male infertility, were obtained. The results showed that piR-mmu-32362259 was the highest differential expression multiples in both the testis tissues of male mice and GC-1 cells similarly. Notably, piR-mmu-32362259 target gene was significantly enriched in the PI3K-AKT signaling pathway. All these results suggest that piR-mmu-32362259 may affect the occurrence and development of injury in the mouse spermatogenesis process by regulating the PI3K-AKT signaling pathway. In order to verify the result, piR-mmu-32362259 low-expression lentivirus was used to transfect GC-1 cells to establish a stable transfected cell model. The effects of piR-mmu-32362259 on the viability, cycle and apoptosis as well as related protein expression levels of GC-1 cells induced by Ni NPs were detected using CCK8, flow cytometry and western blot assay, respectively. The results showed that low expression of piR-mmu-32362259 could not only alleviate the decrease of GC-1 cell viability, affect the cell cycle and reduce the apoptosis rate, but also significantly affect the expression levels of key proteins and their downstream molecules of PI3K/AKT/mTOR signaling pathway. Collectively, our current results provide a theoretical basis for further exploring the molecular regulatory mechanism of male reproductive toxicity induced by Ni NPs.