Evaluation of oxidative stress and genotoxicity in battery manufacturing workers occupationally exposed to lead

Comparison of sensitivity between blood parameters and a genotoxic biomarker at low blood Pb levels: A population-based study

BACKGROUND

Previous studies reported that lead (Pb) exposure induced adverse health effects at high exposure concentrations, however, there have been limited data on sensitivity comparisons among different health outcomes at low blood Pb levels.

OBJECTIVES

To compare sensitivity between blood parameters and a genotoxic biomarker among workers exposed to low blood Pb levels (< 20 µg/dl), and to estimate a benchmark dose (BMD).

METHODS

Pb-exposed workers were recruited from a lead-acid storage battery plant. Their blood lead levels (BLLs) were measured. Blood parameters and micronuclei (MN) frequencies were determined. Multivariate linear or Poisson regression was used to analyze relationships between blood parameters or MN frequencies with BLLs. Two BMD software were used to calculate BMD and its 95 % lower confidence limit (BMDL) for BLLs.

RESULTS

The median BLL for 611 workers was 10.44 µg/dl with the 25th and 75th percentile being 7.37 and 14.62 µg/dl among all participants. There were significantly negative correlations between blood parameters and BLLs. However, MN frequencies correlated positively with BLLs (all P<0.05). Results from the two BMD software revealed that the dichotomous model was superior to the continuous model, and the BMDL for BLL derived from red blood cell (RBC) was 15.11 µg/dl, from hemoglobin (HGB) was 8.50 µg/dl, from mean corpuscular hemoglobin (MCH) was 7.87 µg/dl, from mean corpuscular hemoglobin concentration (MCHC) was 3.98 µg/dl, from mean corpuscular volume (MCV) was 11.44 µg/dl, and from hematocrit (HCT) was 6.65 µg/dl. The conservative BMDL obtained from the MN data was 7.52 µg/dl.

CONCLUSION

Our study shows that low dose Pb exposure caused decrease of blood parameters and increase of MN frequencies. The genotoxic biomarker was more sensitive than most blood parameters. BMDLs for BLL derived from MN frequencies and the red blood cell indicators should be considered as new occupational exposure limits. Our results suggest that MN assay can be considered as a part of occupational health examination items.

Low-level, chronic ingestion of lead and cadmium: The unspoken danger for at-risk populations

The long-term effects of low-level, chronic exposure to lead and cadmium through ingestion are often overlooked, despite the urgency surrounding the clinical onset and worsening of certain pathologies caused by these metals. This work reviews current legislation, global ingestion levels, and blood levels in the general population to emphasize the need for reactivity towards this exposure, especially in at-risk populations, including patients with early-stage renal and chronic kidney disease. Global data indicates persistent chronic ingestion of lead and cadmium, with no decreasing trend in recent years, and a daily consumption of tens of micrograms worldwide. Moreover, the average blood lead and cadmium levels in the general population are concerning in many countries with some significantly exceeding healthy limits, particularly for children. Technologies developed to cleanse soil and prevent heavy metal contamination in food are not yet applicable on a global scale and remain financially inaccessible for many communities. Addressing this chronic ingestion at the human level may prove more beneficial in delaying the onset of associated clinical pathologies or preventing them all together.

Use of micronucleus cytome assays with buccal cells for the detection of genotoxic effects: A systematic review and meta-analysis of occupational exposures to metals

Micronucleus (MN) assays with buccal cells are at present widely used to investigate occupational exposures to genotoxic carcinogens. This article describes their use for the monitoring of metal exposed workers. We found in total 73 relevant articles, in the majority (97 %) increased MN and/or other nuclear anomalies were reported. Most studies were realized in South East Asia and South America. A variety of different occupations was studied including welders, electroplaters, painters, workers in battery recycling and production, tannery workers, dental technicians, miners, workers in foundries and smelters, and also subjects working in waste recycling, glass, aluminum and steel production. In many investigations the effects increased with the duration of the working period. The quality of individual studies was evaluated with a quality score tool. The number of cells was in most studies sufficient and DNA-specific stains were used. However, many studies have shortcomings, e.g. they focused solely on MN formation and did not evaluate anomalies, which provide additional information about the stability of the genetic material and acute cytotoxic effects. Only 35 % of the investigations contain quantitative information about exposures to metals and other toxicants. In 6 of these studies, correlations were observed between the concentrations of specific metals (As, Pb, Cr, Cd) in body fluids and MN frequencies. Taken together, the available data indicate that the MN assay can be used to detect chromosomal damage in metal exposed groups; furthermore, it enables also comparisons between subgroups differing in regard to their exposure and allows an estimation of the efficiency of protective measures. The exposure of workers to metals is currently controlled with chemical analytical measurements only, MN assays with buccal cells could contribute to further improve the safety at workplaces as they reflect the biological consequences including synergistic and antagonistic interactions between toxicants.

Impact of DNA repair polymorphisms on DNA instability biomarkers induced by lead (Pb) in workers exposed to the metal

Although the mechanisms of Pb-induced genotoxicity are well established, a wide individual's variation response is seen in biomarkers related to Pb toxicity, despite similar levels of metal exposure. This may be related to intrinsic variations, such as genetic polymorphisms; moreover, very little is known about the impact of genetic variations related to DNA repair system on DNA instability induced by Pb. In this context, the present study aimed to assess the impact of SNPs in enzymes related to DNA repair system on biomarkers related to acute toxicity and DNA damage induced by Pb exposure, in individuals occupationally exposed to the metal. A cross-sectional study was run with 154 adults (males, >18 years) from an automotive batteries' factory, in Brazil. Blood lead levels (BLL) were determined by ICP-MS; biomarkers related to acute toxicity and DNA instability were monitored by the buccal micronucleus cytome (BMNCyt) assay and genotyping of polymorphisms of MLH1 (rs1799977), OGG1 (rs1052133), PARP1 (rs1136410), XPA (rs1800975), XPC (rs2228000) and XRCC1 (rs25487) were performed by TaqMan assays. BLL ranged from 2.0 to 51 μg dL^-1 (mean 20 ± 12 μg dL^-1) and significant associations between BLL and BMNCyt biomarkers related to cellular proliferation and cytokinetic, cell death and DNA damage were observed. Furthermore, SNPs from the OGG1, XPA and XPC genes were able to modulate interactions in nuclear bud formation (NBUDs) and micronucleus (MNi) events. Taken together, our data provide further evidence that polymorphisms related to DNA repair pathways may modulate Pb-induced DNA damage; studies that investigate the association between injuries to genetic material and susceptibilities in the workplace can provide additional information on the etiology of diseases and the determination of environmentally responsive genes.

Health risk assessment associated with heavy metals through fractioned dust from coal and chromite mines in Pakistan

Heavy metals exposure through dust emissions pose a health risk to workers in coal and chromite mines. The processes involved in mining are noteworthy for the generation of heavy metal-contaminated dust which causes human health implications, especially to the workers that are mainly exposed to such toxins. This study determined pollution levels in coal and chromite mines and calculated the health risk of workers being exposed to heavy metal-contaminated dust. We used fractioned dust with particle sizes < 75, 75-106, and 107-150 µm to assess the pollution levels, anthropogenic impacts, geo-accumulation index, and enrichment factor for selected coal and chromite mines. Through a probabilistic approach, Monte Carlo simulations were used to determine health risks. The findings revealed that the smallest size dust fraction (< 75 μm) contained the highest metal concentrations. Ingestion was considered a prominent exposure route contributing to health risk. In the dust fraction (< 75 μm), chromite mines exhibited the highest Cr (340.6 mg/kg) and lowest Cd (8.4 mg/kg) concentrations. In coal mines, Mn (284.9 mg/kg) and Cd (2.1 mg/kg) were measured highest and lowest, respectively. Pollution assessment revealed dust to be moderately polluted. Health risk assessment showed that Cr in chromite mines exhibited a mean HI value of 1.16E + 00 that was higher than the safe level (HI > 1) having the potential to cause significant health risk to workers. In coal mines, the estimated total HI was 6E-1. Sensitivity analysis revealed concentration and exposure time to be the most influential parameters contributing to risk. Therefore, governmental and nongovernmental organizations must develop dust pollution control guidelines and mitigation measures to safeguard the health of mineworkers by limiting heavy metal exposure.

Reduced DNA Glycosylases Expression and Oxidative DNA Damage Induced by Lead

Exposure to lead (Pb) continues to be a significant worldwide problem. Pb is a highly toxic heavy metal affecting several organ systems in the body. There has been reported to have potential genotoxic properties to various cells. However, the underlying mechanisms of lead-induced toxicity are still unknown. The present study aimed to investigate the lead-induced cytotoxicity in human renal proximal tubular epithelial cells and its underlying DNA damage mechanisms. Lead exposure caused DNA damage as demonstrated by increased 8-OHdG/dG ratio in cells even at a relatively normal dose (10μg/dL). Lead also led to producing oxidative stress as characterized by increased intensity of the Reactive Oxygen Species (ROS) indicator. ROS overproduction should be the reason for lead-induced DNA damage. Therefore, the effects of Lead on ROS elimination should be the main reason for lead-induced oxidative stress in human renal proximal tubular epithelial cells. After lead acetate (PbAc) treatment, the cell viability significantly decreased in a dose-dependent manner, and the accumulation of cellular ROS was observed. 8-OHdG levels, a marker of oxidative DNA damage, were significantly increased by both acute and chronic Pb exposure. Interestingly, the mRNA expression of the 8-oxoguanine DNA glycosylase 1 (hOGG1) significantly decreased after acute and chronic exposure. In conclusion, our study provides the first evidence to demonstrate that acute and chronic Pb exposure results in the altered expression of DNA glycosylases genes indicating the impairment of DNA repair pathways and contributing to DNA damage. These findings should be useful for the more comprehensive assessment of the toxic effects of Pb.

Association between lead exposure and DNA damage (genotoxicity): systematic review and meta-analysis

Studies suggest that chronic lead (Pb) exposure may induce deoxyribonucleic acid (DNA) damage. However, there is no synthesised evidence in this regard. We systematically reviewed existing literature and synthesised evidence on the association between chronic Pb exposure and markers of genotoxicity. Observational studies reporting biomarkers of DNA damage among occupationally Pb-exposed and unexposed controls were systematically searched from PubMed, Scopus and Embase databases from inception to January 2022. The markers included were micronucleus frequency (MN), chromosomal aberrations, comet assay, and 8-hydroxy-deoxyguanosine. During the execution of this review, we followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Mean differences in the biological markers of DNA damage between Pb-exposed and control groups were pooled using the random-effects model. The heterogeneity was assessed using the Cochran-Q test and I² statistic. The review included forty-five studies comparing markers of DNA damage between Pb-exposed and unexposed. The primary studies utilised buccal and/or peripheral leukocytes for evaluating the DNA damage. The pooled quantitative results revealed significantly higher DNA damage characterised by increased levels of MN and SCE frequency, chromosomal aberrations, and oxidative DNA damage (comet assay and 8-OHdG) among Pb-exposed than the unexposed. However, studies included in the review exhibited high levels of heterogeneity among the studies. Chronic Pb exposure is associated with DNA damage. However, high-quality, multicentred studies are required to strengthen present observations and further understand the Pb's role in inducing DNA damage. CRD42022286810.

Lead acetate versus cadmium sulfate in the modulation of main physiological pathways controlling detrusor muscle contractility in rat

Heavy metals have a deleterious effect on lower urinary tract functions. Scant data has been reported about metals’ effect on altering detrusor muscle contractility. Rats were given lead acetate (3, 30 mg/kg), cadmium sulfate (0.1, 1 mg/kg) or ferrous sulfate-iron overload-(3, 30 mg/kg), in a subacute toxicity study (21 days, ip). In-vitro tension experiments were conducted using isolated rat detrusor muscle. Measurement of heavy metal concentrations in blood and tissue homogenates was performed, as well as histopathological examinations. Subacute toxicity induced by treatment with lead and cadmium was manifested as a decrease in EFS, ACh, and ATP-mediated contraction of isolated detrusor muscle. Iron overload only decreased E_MAX of EFS and ACh-mediated contraction. Lead (30 mg/kg) caused an upward shift in the dose response curve of isoprenaline-induced relaxation, with a significant decrease in E_MAX. Lead (30 mg/kg) or cadmium (1 mg/kg) inhibited adenosine (10⁻⁵ M)-induced relaxation. Comparisons to control tissues showed a selective accumulation of metals in the detrusor muscle. Histopathological examinations revealed edema and inflammation in the urinary bladder. Directly added lead (10 mM) inhibited detrusor muscle contraction in-vitro, and its effect was decreased in presence of atropine, and potentiated in presence of TEA, L-NAME, or MB. Cadmium's (0.1 mM) inhibitory effect was reduced in presence of nifedipine or trifluoperazine. In conclusion, lead, cadmium, or iron induce detrusor hypoactivity: The inhibitory effect of lead may be mediated by modulating muscarinic receptors but not the K⁺/NO/cGMP pathway, whereas cadmium inhibitory effect may be mediated by inhibiting the Ca²⁺/calmodulin pathway.

Neuroprotective Effects of Carnitine and Its Potential Application to Ameliorate Neurotoxicity

Carnitine is an essential metabolite that is absorbed from the diet and synthesized in the kidney, liver, and brain. It ferries fatty acids across the mitochondrial membrane to undergo β-oxidation. Carnitine has been studied as a therapy or protective agent for many neurological diseases and neurotoxicity (e.g., prolonged anesthetic exposure-induced developmental neurotoxicity in preclinical models). Preclinical and clinical data support the notion that carnitine or acetyl carnitine may improve a patient's quality of life through increased mitochondrial respiration, release of neurotransmitters, and global gene expression changes, showing the potential of carnitine beyond its approved use to treat primary and secondary carnitine deficiency. In this review, we summarize the beneficial effects of carnitine or acetyl carnitine on the central nervous system, highlighting protective effects against neurotoxicity-induced damage caused by various chemicals and encouraging a thorough evaluation of carnitine use as a therapy for patients suffering from neurotoxicant exposure.

Circulating lead modifies hexavalent chromium-induced genetic damage in a chromate-exposed population: An epidemiological study

Chromium (Cr) can coexist with other heavy metals in the blood of chronically chromate-exposed individuals. However, few studies have explored the health impacts of other hazardous metals after exposure to hexavalent chromium [Cr(VI)]. This study aimed to assess the modification effects of blood lead (Pb) on the genetic damage induced by Cr(VI). During 2010-2019, 1000 blood samples were collected from 455 workers exposed to chromate and 545 workers not exposed to chromate from the same factory with similar labor intensity. The levels of Cr and Pb were measured in whole blood samples. Micronucleus frequency (MNF) and urinary 8-hydroxydeoxyguanosine (8-OHdG) were measured to reflect different types of genetic damage. Multivariate linear regression analyses were performed to evaluate the associations between hazardous metals and the modification effects of Pb on genetic damage. The geometric mean levels of Cr and Pb in the exposure group were significantly higher than those in the control group [Cr: 6.42 (6.08- 6.79) vs. 1.29 (1.22- 1.36) μg/L; Pb: 38.82 (37.22- 40.50) vs. 34.47 (33.15- 35.85) μg/L]. The geometric means of urinary 8-OHdG and MNF in exposure group were 4.00 (3.64- 4.40) μg/g and 5.40 (4.89- 5.97) ‰, respectively, significantly higher than the 3.20 (2.94- 3.48) μg/g and 4.57 (4.15- 5.03) ‰, respectively, in control group. log₂Cr was independently and positively associated with urinary 8-OHdG (β_-adjusted = 0.143, 95% CI: 0.082- 0.204) and MNF (β_-adjusted = 0.303, 95%CI: 0.020- 0.587). With the change in circulating Pb levels, the types of genetic damage induced by Cr(VI) were different. At low levels of circulating Pb (<30.80 μg/L), chromate mainly caused changes in 8-OHdG, while at high circulating Pb levels (≥44.88 μg/L), chromate induced alterations in MNF. The findings suggested that chromate exposure could cause multiple types of genetic damage, and circulating Pb might modify the association between circulating Cr and the form of genetic damage.

Biomonitoring findings for occupational lead exposure in battery and ceramic tile workers using biochemical markers, alkaline comet assay, and micronucleus test coupled with fluorescence in situ hybridisation

Manufacture of lead-containing products has long been associated with various health risks. To get an insight into the related genotoxic risks, we conducted a biomonitoring study in 50 exposed workers and 48 matched controls using a battery of endpoints that sensitively detect the extent of genome instability in peripheral blood lymphocytes. The levels of primary DNA damage were estimated with the alkaline comet assay, while cytogenetic abnormalities were determined with the cytokinesis-block micronucleus (CBMN) cytome assay. Additionally, CBMN slides of 20 exposed and 16 control participants were subjected to fluorescence in situ hybridisation (FISH), coupled with pancentromeric probes to establish the incidence of centromere-positive micronuclei, nuclear buds, and nucleoplasmic bridges. Blood lead levels (B-Pb) were measured with atomic absorption spectrometry. To further characterise cumulative effects of occupational exposure, we measured erythrocyte protoporphyrin (EP) concentrations and delta-aminolevulinic acid dehydratase (ALAD) activity in blood. We also assessed the influence of serum folate (S-folate) and vitamin B12 (S-B12) on genome stability. Compared to controls, occupationally exposed workers demonstrated significantly higher B-Pb (298.36±162.07 vs 41.58±23.02), MN frequency (18.71±11.06 vs 8.98±7.50), centromere positive MN (C+ MN) (8.15±1.8 vs 3.69±0.47), and centromere negative MN (C- MN) (14.55±1.80 vs 4.56±0.89). Exposed women had significantly higher comet tail intensity (TI) and length (TL) than control women. Furthermore, workers showed a positive correlation between age and nuclear buds and MN, between MN and years of exposure, and between S-B12 levels and TI and ALAD activity, while a negative correlation was found between TI and B-Pb. These findings suggest that occupational settings in the manufacture of lead-containing products pose significant genotoxic risks, which calls for developing more effective work safety programmes, including periodical monitoring of B-Pb and genetic endpoints.

Development of a benchmark dose for lead-exposure based on its induction of micronuclei, telomere length changes and hematological toxicity

BACKGROUND

Excessive lead exposure is associated with adverse health effects. However, there is a lack of systematic investigation using large populations to ascertain acceptable exposure limits.

OBJECTIVES

Our study was aimed to identify human exposure-response relationships between lead exposure and health-related outcomes, and to determine a benchmark dose (BMD).

METHODS

A total of 1896 participants from a lead-acid battery plant were recruited. Blood lead levels (BLLs) were detected for all participants. Hematological parameters (n = 1896), micronuclei (MN) frequencies (n = 934), and relative telomere length (rTL) (n = 757) were also determined. Multivariate linear/Poisson regression analyses were performed to examine associations between BLLs and these health outcomes. Restricted cubic splines were used to identify dose-response relationships. Three BMD approaches were used to calculate BMD and its 95% lower confidence limit (BMDL).

RESULTS

Among all participants, BLLs show a right-skewed distribution (median, 185.40 μg/L; 25th - 75th percentile, 104.63-271.70 μg/L). There existed significant differences for red blood cell (RBC), hemoglobin (Hb), MN and rTL among different BLL dose groups. After adjusting for possible confounders, all indicators were significantly associated with BLLs. Restricted cubic splines show that there were linear dose-response relationships for RBC and Hb with BLLs, while non-linear for MN and rTL. Results from the three BMD approaches indicate that the dichotomous models were better than continuous models to calculate BMD and BMDL of BLLs. The conservative BMDL obtained from RBC data was 135 for total, 104 for male and 175 μg/L for female. The corresponding BMDL obtained from Hb data was 105 for total, 116 for male and 70 μg/L for female. As for MN data, the BMDL estimate was 66 for total, 69 for male and 64 μg/L for female. Finally, the BMDL from rTL data was 35 for total, 32 for male and 43 μg/L for female.

CONCLUSIONS

Our data show significant dose-response relationships between lead exposure and expressions of hematological toxicity and genotoxicity. The new BMDLs of 135 and 105 μg/L based on RBC and Hb, and even more strict level of 66 and 35 μg/L based on MN and rTL are lower than current exposure limits in China. Therefore, the four values can be considered as novel exposure limits. In addition, sex effect should be taken into account when setting occupational health standard. Considering that different biomarkers have different sensitivities, better understanding their relationships will certainly improve the current emphasis on precision health risk assessment.

Hepatoprotective activity of okra (Abelmoschus esculentus L.) in sodium nitrite-induced hepatotoxicity

Background and Aim:

For years, people have used sodium nitrite as a food preservative. This study determined the effect of okra (Abelmoschus esculentus L.) pod methanol extract (OPME) on mice with hepatotoxicity induced by sodium nitrite. The flavonoid and total phenolic levels, serum biochemistry, and liver histology were examined.

Materials and Methods:

Green okra pod extraction was performed using ethanol methanol solvent. Thirty adult male BALB/c mice (8-10 weeks, ~30 g) were divided into six groups: Normal control, negative control (sodium nitrite 50 mg/kg BW exposure), and treatment groups (sodium nitrite exposure and OPME at doses of 50, 100, 200, and 400 mg/kg BW). Subsequently, they were exposed to sodium nitrite and administered multiple doses of OPME for 19 days by gavage. After that, serum was used for biochemical evaluation, and liver histological analysis was performed. All data were statistically analyzed (α=0.05).

Results:

All doses of OPME reduced the levels of nitric oxide (NO), malondialdehyde (MDA), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). In this research, both superoxide dismutase (SOD) and catalase (CAT) levels increased in all OPME-administered treatments. All doses also reduced necrotic cells, proportion of swollen cells, and inflammation in liver histological analysis. The results of this study showed that OPME exerted hepatoprotective effects by lowering MDA, NO, ALT, and AST levels. It also improved SOD and CAT levels and recovered damaged liver tissue to its normal state. The optimal dose of OPME was 50-100 mg/kg BW.

Conclusion:

OPME has potential as a natural hepatoprotective agent against sodium nitrite exposure.

Recurrent Indoor Environmental Pollution and Its Impact on Health and Oxidative Stress of the Textile Workers in Bangladesh

Perennial indoor environmental pollution in the textile industrial area is a potential health hazard for workers engaged in this line of work, resulting in mental aberration to severe health risks. This study was designed to investigate the indoor environmental quality of textile industries and correlate its effect on the occupational health and well-being of the textile workers by measuring plasma oxidative stress status in textile workers and healthy control subjects. Environmental samples were collected from 15 textile industries located in Dhaka division, and 30 volunteer textile workers and 30 volunteer office workers (control) aged 18 to 57 years participated in the study. The concentration of plasma ascorbic acid (P-ASC), plasma malondialdehyde (P-MDA), and plasma conjugated diene (P-CD) was measured in both groups. The noise level (78.0 ± 0.68 dB) and the formaldehyde level (141.80 ± 4.47 µg/m³) were found to be significantly higher in the indoor environmental area compared with those in the control area (70.17 ± 0.25 dB and 108.0 ± 0.76 µg/m³, respectively). Furthermore, the daily average concentration of suspended particulate matters (PMs), that is, PM_2.5 (322.2 ± 13.46 µg/m³) and PM₁₀ (411.0 ± 17.57 µg/m³), was also found to be significantly higher in the indoor environmental air compared with that in the control area (78.59 ± 1.66 and 174.0 ± 2.33 µg/m³, respectively). The levels of P-MDA (0.37 ± 0.03 nmol/L) and P-CD (14.74 ± 0.61 nmol/L) were significantly increased, whereas the level of P-ASC level (0.46 ± 0.04 mg/dL) was markedly decreased in the textile workers compared with the healthy control subjects (0.18 ± 0.01 nmol/L of P-MDA, 10.04 ± 0.44 nmol/L of P-CD, and 1.29 ± 0.06 mg/dL of P-ASC). The textile plants were found to have significantly elevated levels of indoor environmental pollutants compared with those in the control area, and the textile workers were significantly exposed to oxidative stresses compared with the control subjects. The use of noise pads and high-efficiency air filters is perhaps highly instrumental to put an end to this prevailing situation. Moreover, to overcome the oxidative stresses among workers, supplementation of antioxidant vitamins (ie, ascorbic acid and/or vitamin E) may be beneficial. In addition, to prevent serious health-related issues, proper precautions should be taken to protect the occupational health of the textile workers.

Effect of lead on proliferation, oxidative stress and genotoxic damage of 3T3-L1 fibroblasts

Lead (Pb) is an environmental and industrial contaminant that still represents a public health problem. In this paper, we investigated the effect of Pb on proliferation, lipid peroxidation and the number of micronucleated cells in exponentially growing 3T3-L1 fibroblasts, a cell line previously used to evaluate different environmental contaminants. We found that Pb (10 μM or higher) was able to inhibit proliferation of exponentially growing cells after 24-h treatment, which was evaluated by the MTT assay and cell counting in Neubauer chamber, but cell survival was not affected according to the trypan blue exclusion assay. On the other hand, Pb was able to increase lipid peroxidation and the number of micronucleated cells, which are indicative of oxidative stress and genotoxic damage respectively. We also found that removal of Pb after 24-h treatment allowed cells to recover proliferation. Our results indicate that Pb was able to induce oxidative stress and genotoxicity in this cell line under standardized conditions, which supports the involvement of Pb in similar effects observed in human exposed to this heavy metal. In addition, Pb inhibits proliferation of exponentially growing fibroblasts but cells resume proliferation after removal of this metal, which suggests that it is important to move away Pb-exposed individuals from the source of contamination.

Implication of Physiological and Biochemical Variables of Prognostic Importance in Lead Exposed Subjects

The use of leaded gasoline adversely affects cardiovascular, nervous, and immune systems. Study projects to rule out different variables of prognostic importance in lead-exposed subjects. A total of 317 traffic wardens with 5 years of outdoor experience and Hb levels < 10 µg/dl, and 100 traffic wardens with indoor duties were substituted in two groups. Levels of vitamins, cytokines, lead, iron, minerals, oxidative stress, and lipid peroxidation were estimated with help of their standard ELISA and spectrophotometric methods respectively. The present study show increased levels of lead in subjects (29.8 ± 3.8 vs. 1.5 ± 0.2 µg/dl) that may be involved in increasing oxidative stress, i.e., levels of malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), and isoprostanes were increased in subjects (4.6 ± 0.5, 4.3 ± 0.6 and 37.2 ± 5.1). Moreover, levels of antioxidants, i.e., superoxide dismutase (SOD), glutathione (GSH), and catalase (CAT), were decreased. It also exhibits reduced levels of different enzymes in anemic traffic wardens. Current study concludes that wardens exposed to environmental lead are more susceptible to develop cardiovascular and neurological disorders. It shows that toxicity of lead maybe responsible for redox imbalance and production of proinflammatory cytokines. Thus, early detection of these biomarkers may help to reduce lead toxicity and it also may help to control the dilemma of uncontrolled environmental pollution by implicating strict actions against substandard gasoline.

Protective effects of spirulina against hemato-biochemical alterations, nephrotoxicity, and DNA damage upon lead exposition

The current study was aimed at exploring the protective efficacy of spirulina against the hemato-biochemical alterations and nephrotoxicity induced by lead (Pb). Female rats aged 12 weeks were treated for 4 weeks with Pb (0.344 g kg^-1 bw) associated or not with spirulina (5.3 g kg^-1 bw). Renal damage induced by Pb was related to a severe anemia, increases of oxidative stress-related parameters (thiobarbituric acid reactive substances (TBARS) (+29%), protein carbonyl (PCO) (+66.3%), and advanced oxidation protein product (AOPP) (+110%)), plasma lactate dehydrogenase (LDH) (+80%), creatinine and urea levels in plasma, and uric acid concentration in urine, as well as genotoxic changes (+89.3% and +60% for DNA and mRNA levels, respectively). Conversely, LDH and antioxidant enzyme activities in kidney were decreased, as well as the levels of plasma uric acid, and urinary creatinine and urea levels. Spirulina-supplemented rats exhibited normal peripheral blood and renal parameters and renal histology. It can be suggested that Arthrospira platensis alleviates damages induced by Pb, thanks to its high phenolic content and antioxidant capacity.

Antioxidant and Nephroprotective Effects of Okra Pods Extract (Abelmoschus esculentus L.) against Lead Acetate-Induced Toxicity in Mice

In this study, we determine the curative effects of okra pods (Abelmoschus esculentus L.) extract against lead acetate toxicity in mice kidney. n-Hexane, ethyl acetate, and methanol solvent were used for extracting okra pods. The role of the extract as an antioxidant was tested by DPPH and FRAP methods. The methanol extract was used for experiments in animals. A total of 30 male BALB/c mice were randomly divided into six equal groups: normal control, negative control (lead-induced), and treatment groups (lead-induced for 28 days and administration of methanol extract at doses of 50, 100, 200, and 400 mg/kg BW for the 28 days). The following were analyzed in all groups: activity of the antioxidant enzymes, namely, superoxide dismutase (SOD) and catalase (CAT); oxidant level, namely, malondialdehyde (MDA) and nitric oxide (NO); and markers of kidney injury, namely, blood urea nitrogen (BUN) and creatinine (Cre). Kidney histopathology was also evaluated. This study showed that the methanol extract showed the highest antioxidant activity (IC₅₀ is 35.21 µg/mL, and FRAP is 57.58 µM Fe^2+/g). The CAT and SOD activities increased significantly in okra-treated groups (P < 0.05). The okra administration groups experienced a significant decrease in MDA, NO, BUN, and Cre levels (P < 0.05). Thickness of the epithelial proximal tubule, diameter of the proximal tubule, and percentage of necrotic cells in proximal tubule decreased, but the diameter ratio of glomerular Bowman's capsule in mice treated with okra was optimally improved and repaired like normal control (P < 0.05). The results of this study reveal that methanol extract has a very strong antioxidant effect and can reduce the influence of toxicity induced by lead acetate in mice kidney.

Vitamin C and Turmeric Attenuate Bax and Bcl-2 Proteins' Expressions and DNA Damage in Lead Acetate-Induced Liver Injury

Background:

Lead is a common environmental and occupational pollutant which induced multiorgans dysfunction. The present study was designed to investigate the hepatoprotective effects of turmeric (TUR) and/or vitamin C (Vit-C) alone or together against lead acetate toxicity and to explore novel molecular pathways.

Method:

Acute hepatotoxicity was induced by lead acetate (100 mg/kg/day, i.p.) in male rats, and the effect of TUR (200 mg/kg/day, orally) and/or Vit-C (250 mg/kg/day, orally) along with lead acetate for 7 days was studied.

Results:

Lead acetate increased serum alanine transaminase, aspartate transaminase, lactate dehydrogenase, hepatic lipid peroxidation and nitric oxide; while, hepatic superoxide dismutase and glutathione activities were downregulated. Hepatic Bcl-2-associated X (Bax) and B-cell lymphoma-2 (Bcl-2) proteins expressions were altered and hepatic DNA damaged was increased as well. Liver/body weight ratio was decreased. Hematoxylin and eosin demonstrated that lead acetate induced focal areas of massive hepatic degeneration of the hepatocytes. Treatment with both antioxidants ameliorated all the altered parameters and induced marked improvement of liver architecture.

Conclusion:

The combination of TUR and Vit-C has shown the most protective effects against lead acetate-induced hepatotoxicity.

Antigenotoxic effects of morin against lead induced genomic damage in cultured human peripheral blood lymphocytes

Lead (Pb) is a well-known carcinogenic heavy metal. Exposure to Pb induces DNA damage by enhancing the generation of reactive oxygen species (ROS). One of the possible ways to shield DNA from this damage is to supply antioxidants that can remove free radicals generated by genotoxicants. Hence, the current study was designed to evaluate the antigenotoxic potential of a flavonoid compound; morin against Pb-induced genomic damage on cultured human peripheral blood lymphocytes (PBL). The effect of Pb or morin or their combination was evaluated on the DNA damage using comet and sister chromatid exchange (SCE) assays. The results indicated a significant (p < 0.05) increase in the SCE frequency and various comet parameters in a dose-dependent manner upon treatment with lead as compared to control in cultured PBL. Supplementation of morin along with Pb effectively negated DNA damage as measured by SCE frequency and comet parameters. PRACTICAL APPLICATIONS: Results of our current study suggest that the DNA damage induced by genotoxicants can be overcome by co-treatment with natural antioxidants, found in dietary supplements such as vegetables and fruits.

Lead modulated Heme synthesis inducing oxidative stress mediated Genotoxicity in Drosophila melanogaster

The mechanism of lead (Pb) modulated heme synthesis pathway induced oxidative stress mediated genotoxicity using standard (ST) and high bioactivation (HB) crosses of Drosophila melanogaster was addressed in the present study. Third instar larvae derived from the ST or HB crosses were reared in sub lethal concentrations of lead acetate (PbAc) treated food media and showed that Pb was readily taken up and accumulated in the said crosses. Pb modulated heme synthesis was evident by significant reductions of δ-aminolevulinic acid dehydratase (δ-ALA-D) and cytochrome P450 (CYP450) and increased accumulation of δ-aminolevulinic acid (δ-ALA). The results have also demonstrated that Pb induced oxidative stress by overproducing reactive oxygen species (ROS) and lipid peroxidation (LPO) and depletion of the antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and glutathione-s-transferase (GST). Wing somatic mutation and recombination test (SMART) using ST and HB crosses revealed that Pb is mutagenic and weakly recombinogenic. By employing larval hemocytes, there was an increase in percent of tail DNA in alkaline comet compared to that of neutral comet revealing the DNA single strand breaks were the products of Pb modulated heme synthesis pathway induced oxidative free radicals. Based on these findings, it can be concluded that Pb modulated heme synthesis pathway induces oxidative stress that mediates the genotoxicity in D. melanogaster.

Potential protective effects of the edible alga Arthrospira platensis against lead-induced oxidative stress, anemia, kidney injury, and histopathological changes in adult rats

Oxidative damage has been proposed as a possible mechanism involved in lead toxicity. This study investigated the possible protective effect of dietary Arthrospira platensis supplementation against lead acetate-induced kidney injury in adult male rats. Rats were divided into 4 groups: normal rats (control rats), rats treated with spirulina, rats treated with lead (Pb) (0.344 g/kg body weight), and rats treated with Pb and spirulina. The exposure of rats to Pb for 30 days provoked renal damage with significant increases in hematological parameters, oxidative stress-related parameters (i.e., thiobarbituric acid reactive substances, protein carbonyl content, advanced oxidation protein products, and hydrogen peroxide), creatinine and urea levels in plasma, and uric acid level in urine. Conversely, antioxidant enzyme activities (i.e., catalase, glutathione peroxidase, and superoxide dismutase) and levels of nonprotein thiols, plasma uric acid, and urinary creatinine and urea decreased. The administration of spirulina to Pb-treated rats significantly improved weight, peripheral blood parameters, oxidative stress-related parameters, renal biomarker levels, and antioxidant enzyme activities. Also, rats treated with Pb and spirulina had normal kidney histology. These healing effects are likely the result of the high phenol content and significant antioxidant capacity of A. platensis. Our data strongly suggest that spirulina supplementation improves kidney function and plays an important role in the prevention of complications of Pb intoxication.

Lead Induces Genotoxicity via Oxidative Stress and Promoter Methylation of DNA Repair Genes in Human Lymphoblastoid TK6 Cells

Background

Lead (Pb) is a widely used metal in modern industry and is regarded as a health hazard. Although lead-induced genotoxicity has been confirmed, the direct evidence that lead induces genotoxicity in human cells and its related mechanisms has not been fully elucidated. In this study, for the first time, we evaluated the genotoxicity induced by lead in human lymphoblastoid TK6 cells.

Material/Methods

The TK6 cells were incubated with various concentrations of Pb(Ac)₂ for 6 h, 12 h, or 24 h. Cell viability was detected by CCK8 assay. Various biochemical markers were assessed by specific kits. Immunofluorescence assay was used to detect γ-H2AX foci formation. The promoter methylation was assessed by methylation-specific PCR. The protein levels were determined by Western blot assay.

Results

The results showed that after exposure to lead, cell viability was obviously decreased and γ-H2AX foci formation was significantly enhanced in TK6 cells. Moreover, the levels of 8-OHdG, ROS, MDA, and GSSG were increased, while the GSH level and SOD activity were decreased in lead-treated TK6 cells. The activation of the Nrf2-ARE signaling pathway was involved in lead-induced oxidative stress in TK6 cells. Finally, the expressions of DNA repair genes XRCC1, hOGG-1, BRCA1, and XPD were inhibited via enhancing their promoter methylation in TK6 cells after exposure to lead.

Conclusions

Taken together, our study provides the first published evidence that lead exposure results in DNA damage via promoting oxidative stress and the promoter methylation of DNA repair genes in human lymphoblastoid TK6 cells.

Antioxidant and nephro-protective effect of Juglans regia vegetable oil against lead-induced nephrotoxicity in rats and its characterization by GC-MS

Lead (Pb) intoxication remains a major health hazard causing various deleterious effects especially on renal and hematologic system. The current study elucidated the potential protective effect of JRVO against nephrotoxicity induced by lead. Male rats were randomly divided into three groups: group one (control) received ad libitum distilled water and 1 mL of saline solution (0.9 %) given by intra-peritoneal (i.p) injection, group two (Pb) was kept on tap distilled water and animals were i.p, injected daily with lead every two days from day five until day ten, namely the sacrifice day, and group three (Pb+J) was administered by intra-peritoneal injection of Pb with the same dose and same way with Group two, while JRVO extract was administered daily by gavage during ten days. The exposure of lead reduced the number of red and white blood cells. Besides, plasma biomarkers (urea, uric acid, creatinine, LDH and ALP) levels were reduced. Lipid and protein per-oxidations increased and objectified by high TBARS and PCOs levels, while glutathione peroxidase, superoxide dismutase and catalase activities showed a significant decline after ten-day treatment. Conversely, the JRVO prevented kidney biomarker changes by improving hepatotoxicity induced by lead as evidenced by restoring the biochemical markers cited above to near normal levels. Kidney histoarchitecture confirmed the biochemical parameters and the beneficial role of JRVO. It can be concluded that the administration of JRVO alleviates Pb-induced toxicity, thus demonstrating its potent antioxidant efficacy.

Effects of co-exposure to lead and zinc on redox status, kidney variables, and histopathology in adult albino rats

Lead (Pb) is a toxic metal that induces a wide range of biochemical and physiological effects in humans. Oxidative damage has been proposed as a possible mechanism involved in Pb toxicity. The current study was carried out to evaluate the antioxidant activities of zinc (Zn) supplement against lead acetate-induced kidney injury in rats. In this study, adults male rats were treated for 15 days with Pb (0.344 g/kg body weight (bw)) associated or not with Zn (10 mg/kg bw). Our study showed that supplementation with Zn prevented renal dysfunction as indicated by plasma biomarkers (urea, uric acid, creatinine, lactate dehydrogenase, and alkaline phosphatase levels) and oxidative stress-related parameters (thiobarbituric acid reactive substances, protein carbonyl, advanced oxidation protein product, superoxide dismutase, catalase, glutathione peroxidase, and vitamins (A, E)) in kidney tissue. The corrective effect of Zn on Pb-induced kidney nephrotoxicity recovered normal kidney histology. Overall, this study indicates that Zn alleviated the toxic effects of this heavy metal on renal tissue, suggesting its role as a potential antioxidant and nephroprotective agent.

Ameliorative effects of Spirulina platensis against lead-induced nephrotoxicity in newborn rats: Modulation of oxidative stress and histopathological changes

Our experimental work was aimed at evaluating the safety and protective effects of dietary spirulina supplementation on the kidney of newborn rats, the offspring of lead contaminated lactating mothers. Female rats were randomly divided into four groups: group I (control) was given a normal diet, group II (positive control, S) received a diet enriched with spirulina, group III received only lead through drinking water (Pb), and group IV received both a diet enriched with spirulina and lead contaminated water (S Pb). The treatment of pregnant rats with lead administrated in drinking water, from the 5^th day of pregnancy until day 14 after delivery, induced an increased level of renal lipid peroxidation, protein carbonyl, hydrogen peroxide and advanced oxidation protein product, a decreased renal content of glutathione and antioxidant enzyme activities such as superoxide dismutase, catalase and glutathione peroxidase in newborns. A statistically significant increase of renal DNA, mRNA, hematological parameters as well as in plasma urea and creatinine serum levels and lactate dehydrogenase was seen in pups, while those of uric acid declined. Interestingly, these biochemical modifications were accompanied by a significant decrease of lactate dehydrogenase in kidney, plasma alkaline phosphatase and gamma glutamyl-transpeptidase levels, urinary levels of creatinine and urea. Conversely, supplementation of lead-treated mother's with spirulina alleviated hematotoxicity induced by lead as evidenced, by restoring the biochemical markers cited above to near normal levels. Nevertheless, the distorted histoarchitecture in rat kidney attenuated following spirulina supplementation. It can be then concluded that spirulina is an important protective source against kidney impairments.

Assessment of Lead Exposure and Urinary-δ-aminolevulinic Acid Levels in Male Lead Acid Battery Workers in Tamil Nadu, India

BACKGROUND

Exposure to lead (Pb) affects multiple health outcomes and physiological systems. In adults, even small increases in blood Pb levels have been associated with decreased glomerular filtration rate, increased risk of hypertension and increased incidence of essential tremor. To date, there have been few Pb-exposure assessments using the United States Occupational Health and Safety Administration (OSHA) regulations.

OBJECTIVE

The aim of the present study was to assess Pb-exposure in terms of elevated blood lead levels (BLL) and urinary-δ-aminolevulinic acid (U-δ-ALA) levels of workers exposed to Pb in the lead acid battery industry in Tamil Nadu, India based on Pb exposure regulations set by the American Conference of Governmental Industrial Hygienists (ACGIH) and OSHA.

MATERIALS AND METHODS

BLLs and U-δ-ALA were estimated in 449 male workers exposed to Pb across ten different job categories in a lead acid battery factory. Worker BLLs were estimated using atomic absorption spectrophotometry and U-δ-ALA was estimated using spectrophotometry.

RESULTS

The Biological Exposure Index of the American Conference of Governmental Industrial Hygienists (BEI-ACGIH) were used to assess Pb exposure. BLLs <30 μg/dL were found in 63.5% of workers, and 36.5% of workers had BLLs>30 μg/dL. The present study also assessed Pb exposure using OSHA regulations and found that 83.3% of workers had BLLs <40 μg/dL and 16.7% of workers had BLLs>40 μg/dL. Among these workers, 0.7% of workers had BLLs >60 μg/dL. An excessive excretion of U-δ-ALA (20-40 mg/L) was noted in pasting area workers (2.6%) followed by executives (2.2%) and assembly workers (0.9%).

CONCLUSIONS

Workers in the job categories of pasting and assembly, as well as executives, are at high risk of Pb exposure compared to other job categories. We recommend placing humidifiers on the roof and keeping a water bath closer the to plate cutting area to reduce fugitive Pb dust emissions. We recommended workers with BLLs >60 μg/dL be removed from jobs involving Pb exposure and return to work only when their BLLs are <40 μg/dL.

PARTICIPANT CONSENT

Obtained.

ETHICS APPROVAL

The study was approved by the ethics committee of the Regional Occupational Health Centre (Southern) Bengaluru, part of the National Institute of Occupational Health of India.

COMPETING INTERESTS

The authors declare no competing financial interests.

Evaluation of genotoxic and cytotoxic effects in buccal mucosa cells of welders in the cities of Cubatão and Santos, state of São Paulo, Brazil

Background

Approximately 5 million workers are estimated to be occupationally exposed to welding fumes worldwide. Nickel and chromium are genotoxic metals found in welding fumes, therefore welders are exposed to these metals at the workplace.

Objective

The objective of the present study was to investigate the frequency of cytotoxic and genetic damage in cells harvested from the oral mucosa of welders and also from a group of workers not exposed to metallic fumes.

Methods

A total of 44 individuals, divided into 2 groups - welders and non-welders - were compared using the micronucleus assay technique and cell death (pyknosis, karyorrhexis and karyolysis) on buccal mucosa cells of welding workers. The examined cells were stained with Feulgen/Fast Green. Results: Welders exhibited higher frequency (p<0.05) of cytotoxicity than the group of volunteers not exposed to metallic fumes.

Conclusion

The results of this preliminary study suggest that the frequency of cytotoxic damage in buccal mucosa cells might be higher among welders compared to non-welders.

Ameliorative effects of l-carnitine on rats raised on a diet supplemented with lead acetate

Lead intoxication has been a major health hazard in humans. It affects people at all ages. Its toxicity is associated with various organs of the body and affects different metabolic pathways. Based on histological data, l-carnitine reduced the severity of tissue damage produced as a result of exposure of rats to lead acetate. The main objective of this study was to evaluate the underlying mechanism of protection offered by l-carnitine against lead acetate intoxication using male Sprague-Dawley rats. Forty male Sprague-Dawley rats were randomly divided into four groups with ten rats in each. The first group (G1) served as the control group and animals received standard diet only. The second group (G2) received lead acetate in their diet. The third group (G3) was the l-carnitine treated group and received the normal standard diet supplemented with l-carnitine. While the fourth group (G4) had a diet supplemented with both lead acetate and l-carnitine. At the end of each experiment, blood (serum and whole blood) were collected from each animal and analyzed for the following parameters: serum testosterone levels, serum nitric oxide and serum malondialdehyde. This is in addition to looking at the enzymatic activities of two important enzymes (superoxide dismutase and catalase) and on (glutathione reductase) which are indicative of the antioxidant activities in the whole blood. The results indicated that l-carnitine will counteract the undesirable effects of lead intoxication. It exerted its antioxidant potential by reducing the production of ROS and scavenging free radicals by maintaining and protecting the level of the of antioxidant enzymes SOD, CAT and glutathione peroxidase. Conclusion:l-Carnitine may play an important role in reversing the undesirable effects of lead intoxication. Future studies should be conducted to see whether such an effect is applicable in humans exposed to lead poising.

Genotoxic and Cytotoxic Effects in Exfoliated Buccal and Nasal Cells of Chromium and Cobalt Exposed Electroplaters

Results of a number of studies indicate that electroplaters have increased cancer risks as a consequence of exposure to genotoxic metals such as chromium (VI) and nickel. These effects may be due to induction of damage of the genetic material which plays a key role in the etiology of cancer, and it was found that workers in galvanization factories exhibited increased levels of DNA damage. The aim of the present study was to investigate genetic stability in workers of a bright plating factory who are exposed to chromium (Cr) and cobalt (Co). Exfoliated cells were collected from the buccal and nasal mucosa of workers (n = 42) and matched controls (n = 43) and analyzed for induction of micronuclei (MN) which are formed as a consequence of chromosomal aberrations. In addition, other nuclear anomalies namely nuclear buds (Nbuds) which are formed as a consequence of gene amplification and markers indicating different stages of cell death (condensed chromatin, karyorrhexis, karyolysis, and pyknosis) were also assessed. No evidence was noted for induction of MN, but significantly increased rates of Nbuds in cells from both, buccal and nasal mucosa, were found. Parameters which are indicative for cytotoxic effects were more pronounced in nasal cells and rose with duration of employment period. Overall, our findings indicated that no apparent chromosomal damage occurred in bright electroplaters. However, data demonstrated that acute cytotoxic effects may lead to inflammations and/or lesions in epithelia of the respiratory tract of the workers.

Lead exposure and plasma mRNA expression in ERBB2 gene

Epidemiologic data for carcinogenicity in those exposed to lead (Pb) suggests relations with cancers although the totality of the evidence is inconsistent. Alterations in the expression of ERBB receptors have been studied during the development and malignant transformation of different kinds of human tumors where they induce proliferation, angiogenesis and metastasis generation. Relevant clinical data demonstrate the role of ERBB2 receptors in the development and malignancy of human cancers. Therefore, the objective of the present investigation is to give more information on the link between plasma mRNA expression in ERBB2 gene and lead blood levels in a healthy population. Blood samples, socio‑demographic, exposure and health data were obtained from 48 healthy men. Real‑time polymerase chain reaction assays were performed to detect ERBB2 gene transcripts, ΔΔCt method was used to quantify gene expression. Pb blood level was assayed using high‑resolution sector field inductively coupled mass spectrometry and is expressed in µg/dl. Plasma mRNA expression in ERBB2 gene was 6.44±3.07 ΔΔCt; Pb blood levels was 16.07±6.74 µg/dl. Regression analysis revealed a significant association (r2=0.5345; p<0.0001) between Pb levels and mRNA expression in ERBB2. So far, it has still not been established if the expression of ERBB2 receptors is influenced by Pb exposure. On the base of the above reported data, we believe an in vitro study might be useful, to understand the molecular mechanisms implicated.

Telomere length, telomerase expression, and oxidative stress in lead smelters

The negative health effects caused by lead (Pb) exposure are widely recognized; however, the molecular mechanisms remain unknown. The aim of this study was to assess the effect of occupational Pb exposure on telomere length and to investigate the potential mechanisms leading to telomere shortening. A cohort of 334 male Pb smelters (exposed group) and 60 age-adjusted males unexposed to Pb (control group) were examined. Assessments of relative telomere length (rTL) and telomerase reverse transcriptase (TERT) gene expression were performed using quantitative real-time polymerase chain reactions. Assessments of whole blood Pb (B-Pb) and whole blood cadmium (B-Cd) concentrations and serum selenium concentration (S-Se) were performed using graphite furnace atomic absorption spectrometry. We analyzed total oxidation status (TOS), lipid hydroperoxides (LHPs), malonylodialdehyde levels in serum (MDA) and in erythrocyte hemolysates (MDA-hgb), and 8-hydroxy-deoxy-guanosine (8-OHdG). The Pb-exposed group had higher B-Pb values and shorter rTL than the control group. The arithmetic mean values calculated for B-Pb were 33 µg/dL versus 2.2 µg/dL ( p < 0.0001), and the rTL values were 0.928 and 1.126 relative units ( p = 0.001), respectively, for the Pb-exposed and control groups. The rTL was found to gradually shorten in response to the increasing levels of Pb exposure. The Pb-exposed group also demonstrated a higher level of oxidative stress than the control group, which was indicated by increased TOS and MDA-hgb values. rTL was negatively associated with parameters that indicated increased oxidative stress, including TOS (Spearman’s rank coefficient ( rS) = −0.16; p < 0.01) and MDA-hgb ( rS = −0.17; p < 0.001). No correlations were found between rTL and B-Cd and S-Se or smoking and MDA and LHP levels. Univariate analysis indicated that B-Pb was associated with decreased rTL ( β =−0.0041; p = 0.0063) and that the association between B-Pb and rTL remained significant, even when adjusting for age ( β = −0.0041; p = 0.0065) and in multivariable-adjusted model ( β = −0.0042; p = 0.0063). In conclusion, occupational Pb exposure resulted in decreased rTL and may represent a mechanism that contributes to Pb-related diseases.

Lead Exposure and Oxidative Stress: A Systematic Review

Lead is an environmental toxicant that can induce oxidative stress (OS) via reactive oxygen species (ROS) generation, which has been reported as an important mechanism underlying lead toxicity (Gurer and Ercal 2000; Pande and Flora 2002; Kasperczyk et al. 2004a; Farmand et al. 2005; Verstraeten et al. 2008; Wang et al. 2009; Martinez-Haro et al. 2011). OS occurs when the generation of ROS exceeds the antioxidant system's ability to defend cells against oxidized molecules. ROS is a term generally used to refer to free radicals derived from O2 (e.g., superoxide anions [O2-] and hydroxyl radicals [OH-]) or to non-radical species (e.g. hydrogen peroxide [H2O2]) (Halliwell and Cross 1994).

Assessment of DNA damage as an index of genetic toxicity in welding microenvironments among iron-based industries

Welding is used extensively in different industries. Welders are always at a risk of exposure to a number of gases and metal-containing fumes in their respective microenvironments in which they work. Welding fumes consist of a wide range of complex metal oxide particles which can deposit in different parts of their bodies causing serious health problems. In the present study, 35 welders (age: 33.80 ± 1.04 years) from two iron-based industries have been assessed for DNA damage in peripheral blood lymphocytes using single-cell gel electrophoresis. An equal number of subjects (N = 35; age: 30.40 ± 1.51 years) matched to exposed subjects with respect to sex, age, socioeconomic status, smoking, and alcoholic habits were taken as controls. The results revealed that the damaged cell frequency (DCF) and mean comet tail length (CTL) in welders were significantly higher as compared to the controls (DCF: 69.74 ± 1.68 vs. 31.14 ± 1.67 and CTL: 29.21 ± 1.48 vs. 1.47 ± 0.08; p < 0.05). The effect of confounding factors such as age, duration of exposure, smoking, and drinking habits was also studied. Blood lead levels also showed a positive correlation with duration of exposure and CTL, and the overall results indicated an increased genetic damage as an index of genotoxicity in workers occupationally engaged in welding microenvironments.

Assessment of genotoxic effects of lead in occupationally exposed workers

The genotoxicological effects in 200 lead acid storage battery recycling and manufacturing industry workers in Hyderabad along with matched 200 controls were studied. The genetic damage was determined by comet, micronucleus (MN), and chromosomal aberration (CA) test in peripheral blood lymphocytes (PBL). The MN test was also carried out in buccal epithelial cells (BECs). Pb in ambient air, blood Pb (B-Pb) concentrations, and hematological parameters were measured. The superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), glutathione peroxidase (GPx), and malondialdehyde (MDA) formed were also studied. The results of the present study showed that there was a statistically significant (P < 0.01) increase in mean percent tail DNA, frequency of CA, and MN in PBL as well as in BEC as compared to controls. Pb in ambient air and B-Pb concentrations were found to be significantly higher (P < 0.01). The hematocrit, hemoglobin, and red blood cell values were significantly lowered in Pb-exposed workers in comparison to controls. SOD, GPx, and CAT levels were significantly decreased while GSH and MDA levels increased in exposed group when compared to control group. The present study suggests that environmental health standards should be enforced to control Pb contamination from battery industries to reduce human health risk.